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binutils-gdb/gdb/gdbserver/linux-low.c
Pedro Alves 3e74e146f2 Linux: No need to set ptrace event options in fork/clone children. 
Oleg Nesterov told me that the Linux kernel copies the parent's ptrace
options to fork/clone children, so there's no need for GDB to do that
manually.

I was actually a bit surprised, since I thought the ptracer had to
always set the ptrace options itself, and GDB is indeed calling
PTRACE_SETOPTIONS for each new fork child, if it'll stay attached.

Looking at the history of that code, I found that is was actually I
who added that set-ptrace-options-in-children bit, back in
http://sourceware.org/ml/gdb-patches/2009-05/msg00656.html.  But,
honestly, I don't recall why I needed that.  I think I may have just
blindly believed it was necessary.

I then looked back at the history of all the PTRACE_SETOPTIONS code we
have, and found that gdb never did copy the ptrace options before my
patch.  But, when gdbserver learnt to use PTRACE_EVENT_CLONE, at
http://sourceware.org/ml/gdb-patches/2007-10/msg00547.html, it was
made to do 'ptrace (PTRACE_SETOPTIONS, new_pid, 0,
PTRACE_O_TRACECLONE)' for all new clones.  Hmmm.  But, GDB itself
never did that, so it can't really ever have been necessary, I
believe, otherwise GDB should have been doing it too.

(GDBserver doesn't support following forks, and so naturally doesn't
do any PTRACE_SETOPTIONS on fork children.)

So this patch removes the -I believe- unnecessary ptrace syscalls.

Tested on x86_64 Fedora 17, native/gdbserver, and on x86_64 RHEL5
native/gdbserver (Linux 2.6.18, I think a ptrace-on-utrace kernel).
No regressions.

gdb/
2013-03-22  Pedro Alves  <palves@redhat.com>

	* linux-nat.c (linux_child_follow_fork): Don't call
	linux_enable_event_reporting.
	(linux_handle_extended_wait): Don't call
	linux_enable_event_reporting.

gdb/gdbserver/
2013-03-22  Pedro Alves  <palves@redhat.com>

	* linux-low.c (handle_extended_wait): Don't call
	linux_enable_event_reporting.
2013-03-22 14:52:26 +00:00

5976 lines
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/* Low level interface to ptrace, for the remote server for GDB.
Copyright (C) 1995-2013 Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include "server.h"
#include "linux-low.h"
#include "linux-osdata.h"
#include "agent.h"
#include "gdb_wait.h"
#include <stdio.h>
#include <sys/param.h>
#include <sys/ptrace.h>
#include "linux-ptrace.h"
#include "linux-procfs.h"
#include <signal.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <sys/syscall.h>
#include <sched.h>
#include <ctype.h>
#include <pwd.h>
#include <sys/types.h>
#include <dirent.h>
#include "gdb_stat.h"
#include <sys/vfs.h>
#include <sys/uio.h>
#ifndef ELFMAG0
/* Don't include <linux/elf.h> here. If it got included by gdb_proc_service.h
then ELFMAG0 will have been defined. If it didn't get included by
gdb_proc_service.h then including it will likely introduce a duplicate
definition of elf_fpregset_t. */
#include <elf.h>
#endif
#ifndef SPUFS_MAGIC
#define SPUFS_MAGIC 0x23c9b64e
#endif
#ifdef HAVE_PERSONALITY
# include <sys/personality.h>
# if !HAVE_DECL_ADDR_NO_RANDOMIZE
# define ADDR_NO_RANDOMIZE 0x0040000
# endif
#endif
#ifndef O_LARGEFILE
#define O_LARGEFILE 0
#endif
#ifndef W_STOPCODE
#define W_STOPCODE(sig) ((sig) << 8 | 0x7f)
#endif
/* This is the kernel's hard limit. Not to be confused with
SIGRTMIN. */
#ifndef __SIGRTMIN
#define __SIGRTMIN 32
#endif
#ifdef __UCLIBC__
#if !(defined(__UCLIBC_HAS_MMU__) || defined(__ARCH_HAS_MMU__))
/* PTRACE_TEXT_ADDR and friends. */
#include <asm/ptrace.h>
#define HAS_NOMMU
#endif
#endif
#ifdef HAVE_LINUX_BTRACE
# include "linux-btrace.h"
#endif
#ifndef HAVE_ELF32_AUXV_T
/* Copied from glibc's elf.h. */
typedef struct
{
uint32_t a_type; /* Entry type */
union
{
uint32_t a_val; /* Integer value */
/* We use to have pointer elements added here. We cannot do that,
though, since it does not work when using 32-bit definitions
on 64-bit platforms and vice versa. */
} a_un;
} Elf32_auxv_t;
#endif
#ifndef HAVE_ELF64_AUXV_T
/* Copied from glibc's elf.h. */
typedef struct
{
uint64_t a_type; /* Entry type */
union
{
uint64_t a_val; /* Integer value */
/* We use to have pointer elements added here. We cannot do that,
though, since it does not work when using 32-bit definitions
on 64-bit platforms and vice versa. */
} a_un;
} Elf64_auxv_t;
#endif
/* ``all_threads'' is keyed by the LWP ID, which we use as the GDB protocol
representation of the thread ID.
``all_lwps'' is keyed by the process ID - which on Linux is (presently)
the same as the LWP ID.
``all_processes'' is keyed by the "overall process ID", which
GNU/Linux calls tgid, "thread group ID". */
struct inferior_list all_lwps;
/* A list of all unknown processes which receive stop signals. Some
other process will presumably claim each of these as forked
children momentarily. */
struct simple_pid_list
{
/* The process ID. */
int pid;
/* The status as reported by waitpid. */
int status;
/* Next in chain. */
struct simple_pid_list *next;
};
struct simple_pid_list *stopped_pids;
/* Trivial list manipulation functions to keep track of a list of new
stopped processes. */
static void
add_to_pid_list (struct simple_pid_list **listp, int pid, int status)
{
struct simple_pid_list *new_pid = xmalloc (sizeof (struct simple_pid_list));
new_pid->pid = pid;
new_pid->status = status;
new_pid->next = *listp;
*listp = new_pid;
}
static int
pull_pid_from_list (struct simple_pid_list **listp, int pid, int *statusp)
{
struct simple_pid_list **p;
for (p = listp; *p != NULL; p = &(*p)->next)
if ((*p)->pid == pid)
{
struct simple_pid_list *next = (*p)->next;
*statusp = (*p)->status;
xfree (*p);
*p = next;
return 1;
}
return 0;
}
enum stopping_threads_kind
{
/* Not stopping threads presently. */
NOT_STOPPING_THREADS,
/* Stopping threads. */
STOPPING_THREADS,
/* Stopping and suspending threads. */
STOPPING_AND_SUSPENDING_THREADS
};
/* This is set while stop_all_lwps is in effect. */
enum stopping_threads_kind stopping_threads = NOT_STOPPING_THREADS;
/* FIXME make into a target method? */
int using_threads = 1;
/* True if we're presently stabilizing threads (moving them out of
jump pads). */
static int stabilizing_threads;
/* This flag is true iff we've just created or attached to our first
inferior but it has not stopped yet. As soon as it does, we need
to call the low target's arch_setup callback. Doing this only on
the first inferior avoids reinializing the architecture on every
inferior, and avoids messing with the register caches of the
already running inferiors. NOTE: this assumes all inferiors under
control of gdbserver have the same architecture. */
static int new_inferior;
static void linux_resume_one_lwp (struct lwp_info *lwp,
int step, int signal, siginfo_t *info);
static void linux_resume (struct thread_resume *resume_info, size_t n);
static void stop_all_lwps (int suspend, struct lwp_info *except);
static void unstop_all_lwps (int unsuspend, struct lwp_info *except);
static int linux_wait_for_event (ptid_t ptid, int *wstat, int options);
static void *add_lwp (ptid_t ptid);
static int linux_stopped_by_watchpoint (void);
static void mark_lwp_dead (struct lwp_info *lwp, int wstat);
static void proceed_all_lwps (void);
static int finish_step_over (struct lwp_info *lwp);
static CORE_ADDR get_stop_pc (struct lwp_info *lwp);
static int kill_lwp (unsigned long lwpid, int signo);
static void linux_enable_event_reporting (int pid);
/* True if the low target can hardware single-step. Such targets
don't need a BREAKPOINT_REINSERT_ADDR callback. */
static int
can_hardware_single_step (void)
{
return (the_low_target.breakpoint_reinsert_addr == NULL);
}
/* True if the low target supports memory breakpoints. If so, we'll
have a GET_PC implementation. */
static int
supports_breakpoints (void)
{
return (the_low_target.get_pc != NULL);
}
/* Returns true if this target can support fast tracepoints. This
does not mean that the in-process agent has been loaded in the
inferior. */
static int
supports_fast_tracepoints (void)
{
return the_low_target.install_fast_tracepoint_jump_pad != NULL;
}
struct pending_signals
{
int signal;
siginfo_t info;
struct pending_signals *prev;
};
#ifdef HAVE_LINUX_REGSETS
static char *disabled_regsets;
static int num_regsets;
#endif
/* The read/write ends of the pipe registered as waitable file in the
event loop. */
static int linux_event_pipe[2] = { -1, -1 };
/* True if we're currently in async mode. */
#define target_is_async_p() (linux_event_pipe[0] != -1)
static void send_sigstop (struct lwp_info *lwp);
static void wait_for_sigstop (struct inferior_list_entry *entry);
/* Return non-zero if HEADER is a 64-bit ELF file. */
static int
elf_64_header_p (const Elf64_Ehdr *header, unsigned int *machine)
{
if (header->e_ident[EI_MAG0] == ELFMAG0
&& header->e_ident[EI_MAG1] == ELFMAG1
&& header->e_ident[EI_MAG2] == ELFMAG2
&& header->e_ident[EI_MAG3] == ELFMAG3)
{
*machine = header->e_machine;
return header->e_ident[EI_CLASS] == ELFCLASS64;
}
*machine = EM_NONE;
return -1;
}
/* Return non-zero if FILE is a 64-bit ELF file,
zero if the file is not a 64-bit ELF file,
and -1 if the file is not accessible or doesn't exist. */
static int
elf_64_file_p (const char *file, unsigned int *machine)
{
Elf64_Ehdr header;
int fd;
fd = open (file, O_RDONLY);
if (fd < 0)
return -1;
if (read (fd, &header, sizeof (header)) != sizeof (header))
{
close (fd);
return 0;
}
close (fd);
return elf_64_header_p (&header, machine);
}
/* Accepts an integer PID; Returns true if the executable PID is
running is a 64-bit ELF file.. */
int
linux_pid_exe_is_elf_64_file (int pid, unsigned int *machine)
{
char file[MAXPATHLEN];
sprintf (file, "/proc/%d/exe", pid);
return elf_64_file_p (file, machine);
}
static void
delete_lwp (struct lwp_info *lwp)
{
remove_thread (get_lwp_thread (lwp));
remove_inferior (&all_lwps, &lwp->head);
free (lwp->arch_private);
free (lwp);
}
/* Add a process to the common process list, and set its private
data. */
static struct process_info *
linux_add_process (int pid, int attached)
{
struct process_info *proc;
/* Is this the first process? If so, then set the arch. */
if (all_processes.head == NULL)
new_inferior = 1;
proc = add_process (pid, attached);
proc->private = xcalloc (1, sizeof (*proc->private));
if (the_low_target.new_process != NULL)
proc->private->arch_private = the_low_target.new_process ();
return proc;
}
/* Wrapper function for waitpid which handles EINTR, and emulates
__WALL for systems where that is not available. */
static int
my_waitpid (int pid, int *status, int flags)
{
int ret, out_errno;
if (debug_threads)
fprintf (stderr, "my_waitpid (%d, 0x%x)\n", pid, flags);
if (flags & __WALL)
{
sigset_t block_mask, org_mask, wake_mask;
int wnohang;
wnohang = (flags & WNOHANG) != 0;
flags &= ~(__WALL | __WCLONE);
flags |= WNOHANG;
/* Block all signals while here. This avoids knowing about
LinuxThread's signals. */
sigfillset (&block_mask);
sigprocmask (SIG_BLOCK, &block_mask, &org_mask);
/* ... except during the sigsuspend below. */
sigemptyset (&wake_mask);
while (1)
{
/* Since all signals are blocked, there's no need to check
for EINTR here. */
ret = waitpid (pid, status, flags);
out_errno = errno;
if (ret == -1 && out_errno != ECHILD)
break;
else if (ret > 0)
break;
if (flags & __WCLONE)
{
/* We've tried both flavors now. If WNOHANG is set,
there's nothing else to do, just bail out. */
if (wnohang)
break;
if (debug_threads)
fprintf (stderr, "blocking\n");
/* Block waiting for signals. */
sigsuspend (&wake_mask);
}
flags ^= __WCLONE;
}
sigprocmask (SIG_SETMASK, &org_mask, NULL);
}
else
{
do
ret = waitpid (pid, status, flags);
while (ret == -1 && errno == EINTR);
out_errno = errno;
}
if (debug_threads)
fprintf (stderr, "my_waitpid (%d, 0x%x): status(%x), %d\n",
pid, flags, status ? *status : -1, ret);
errno = out_errno;
return ret;
}
/* Handle a GNU/Linux extended wait response. If we see a clone
event, we need to add the new LWP to our list (and not report the
trap to higher layers). */
static void
handle_extended_wait (struct lwp_info *event_child, int wstat)
{
int event = wstat >> 16;
struct lwp_info *new_lwp;
if (event == PTRACE_EVENT_CLONE)
{
ptid_t ptid;
unsigned long new_pid;
int ret, status;
ptrace (PTRACE_GETEVENTMSG, lwpid_of (event_child), (PTRACE_ARG3_TYPE) 0,
&new_pid);
/* If we haven't already seen the new PID stop, wait for it now. */
if (!pull_pid_from_list (&stopped_pids, new_pid, &status))
{
/* The new child has a pending SIGSTOP. We can't affect it until it
hits the SIGSTOP, but we're already attached. */
ret = my_waitpid (new_pid, &status, __WALL);
if (ret == -1)
perror_with_name ("waiting for new child");
else if (ret != new_pid)
warning ("wait returned unexpected PID %d", ret);
else if (!WIFSTOPPED (status))
warning ("wait returned unexpected status 0x%x", status);
}
ptid = ptid_build (pid_of (event_child), new_pid, 0);
new_lwp = (struct lwp_info *) add_lwp (ptid);
add_thread (ptid, new_lwp);
/* Either we're going to immediately resume the new thread
or leave it stopped. linux_resume_one_lwp is a nop if it
thinks the thread is currently running, so set this first
before calling linux_resume_one_lwp. */
new_lwp->stopped = 1;
/* If we're suspending all threads, leave this one suspended
too. */
if (stopping_threads == STOPPING_AND_SUSPENDING_THREADS)
new_lwp->suspended = 1;
/* Normally we will get the pending SIGSTOP. But in some cases
we might get another signal delivered to the group first.
If we do get another signal, be sure not to lose it. */
if (WSTOPSIG (status) == SIGSTOP)
{
if (stopping_threads != NOT_STOPPING_THREADS)
new_lwp->stop_pc = get_stop_pc (new_lwp);
else
linux_resume_one_lwp (new_lwp, 0, 0, NULL);
}
else
{
new_lwp->stop_expected = 1;
if (stopping_threads != NOT_STOPPING_THREADS)
{
new_lwp->stop_pc = get_stop_pc (new_lwp);
new_lwp->status_pending_p = 1;
new_lwp->status_pending = status;
}
else
/* Pass the signal on. This is what GDB does - except
shouldn't we really report it instead? */
linux_resume_one_lwp (new_lwp, 0, WSTOPSIG (status), NULL);
}
/* Always resume the current thread. If we are stopping
threads, it will have a pending SIGSTOP; we may as well
collect it now. */
linux_resume_one_lwp (event_child, event_child->stepping, 0, NULL);
}
}
/* Return the PC as read from the regcache of LWP, without any
adjustment. */
static CORE_ADDR
get_pc (struct lwp_info *lwp)
{
struct thread_info *saved_inferior;
struct regcache *regcache;
CORE_ADDR pc;
if (the_low_target.get_pc == NULL)
return 0;
saved_inferior = current_inferior;
current_inferior = get_lwp_thread (lwp);
regcache = get_thread_regcache (current_inferior, 1);
pc = (*the_low_target.get_pc) (regcache);
if (debug_threads)
fprintf (stderr, "pc is 0x%lx\n", (long) pc);
current_inferior = saved_inferior;
return pc;
}
/* This function should only be called if LWP got a SIGTRAP.
The SIGTRAP could mean several things.
On i386, where decr_pc_after_break is non-zero:
If we were single-stepping this process using PTRACE_SINGLESTEP,
we will get only the one SIGTRAP (even if the instruction we
stepped over was a breakpoint). The value of $eip will be the
next instruction.
If we continue the process using PTRACE_CONT, we will get a
SIGTRAP when we hit a breakpoint. The value of $eip will be
the instruction after the breakpoint (i.e. needs to be
decremented). If we report the SIGTRAP to GDB, we must also
report the undecremented PC. If we cancel the SIGTRAP, we
must resume at the decremented PC.
(Presumably, not yet tested) On a non-decr_pc_after_break machine
with hardware or kernel single-step:
If we single-step over a breakpoint instruction, our PC will
point at the following instruction. If we continue and hit a
breakpoint instruction, our PC will point at the breakpoint
instruction. */
static CORE_ADDR
get_stop_pc (struct lwp_info *lwp)
{
CORE_ADDR stop_pc;
if (the_low_target.get_pc == NULL)
return 0;
stop_pc = get_pc (lwp);
if (WSTOPSIG (lwp->last_status) == SIGTRAP
&& !lwp->stepping
&& !lwp->stopped_by_watchpoint
&& lwp->last_status >> 16 == 0)
stop_pc -= the_low_target.decr_pc_after_break;
if (debug_threads)
fprintf (stderr, "stop pc is 0x%lx\n", (long) stop_pc);
return stop_pc;
}
static void *
add_lwp (ptid_t ptid)
{
struct lwp_info *lwp;
lwp = (struct lwp_info *) xmalloc (sizeof (*lwp));
memset (lwp, 0, sizeof (*lwp));
lwp->head.id = ptid;
if (the_low_target.new_thread != NULL)
lwp->arch_private = the_low_target.new_thread ();
add_inferior_to_list (&all_lwps, &lwp->head);
return lwp;
}
/* Start an inferior process and returns its pid.
ALLARGS is a vector of program-name and args. */
static int
linux_create_inferior (char *program, char **allargs)
{
#ifdef HAVE_PERSONALITY
int personality_orig = 0, personality_set = 0;
#endif
struct lwp_info *new_lwp;
int pid;
ptid_t ptid;
#ifdef HAVE_PERSONALITY
if (disable_randomization)
{
errno = 0;
personality_orig = personality (0xffffffff);
if (errno == 0 && !(personality_orig & ADDR_NO_RANDOMIZE))
{
personality_set = 1;
personality (personality_orig | ADDR_NO_RANDOMIZE);
}
if (errno != 0 || (personality_set
&& !(personality (0xffffffff) & ADDR_NO_RANDOMIZE)))
warning ("Error disabling address space randomization: %s",
strerror (errno));
}
#endif
#if defined(__UCLIBC__) && defined(HAS_NOMMU)
pid = vfork ();
#else
pid = fork ();
#endif
if (pid < 0)
perror_with_name ("fork");
if (pid == 0)
{
ptrace (PTRACE_TRACEME, 0, (PTRACE_ARG3_TYPE) 0, (PTRACE_ARG4_TYPE) 0);
#ifndef __ANDROID__ /* Bionic doesn't use SIGRTMIN the way glibc does. */
signal (__SIGRTMIN + 1, SIG_DFL);
#endif
setpgid (0, 0);
/* If gdbserver is connected to gdb via stdio, redirect the inferior's
stdout to stderr so that inferior i/o doesn't corrupt the connection.
Also, redirect stdin to /dev/null. */
if (remote_connection_is_stdio ())
{
close (0);
open ("/dev/null", O_RDONLY);
dup2 (2, 1);
if (write (2, "stdin/stdout redirected\n",
sizeof ("stdin/stdout redirected\n") - 1) < 0)
{
/* Errors ignored. */;
}
}
execv (program, allargs);
if (errno == ENOENT)
execvp (program, allargs);
fprintf (stderr, "Cannot exec %s: %s.\n", program,
strerror (errno));
fflush (stderr);
_exit (0177);
}
#ifdef HAVE_PERSONALITY
if (personality_set)
{
errno = 0;
personality (personality_orig);
if (errno != 0)
warning ("Error restoring address space randomization: %s",
strerror (errno));
}
#endif
linux_add_process (pid, 0);
ptid = ptid_build (pid, pid, 0);
new_lwp = add_lwp (ptid);
add_thread (ptid, new_lwp);
new_lwp->must_set_ptrace_flags = 1;
return pid;
}
/* Attach to an inferior process. */
static void
linux_attach_lwp_1 (unsigned long lwpid, int initial)
{
ptid_t ptid;
struct lwp_info *new_lwp;
if (ptrace (PTRACE_ATTACH, lwpid, (PTRACE_ARG3_TYPE) 0, (PTRACE_ARG4_TYPE) 0)
!= 0)
{
struct buffer buffer;
if (!initial)
{
/* If we fail to attach to an LWP, just warn. */
fprintf (stderr, "Cannot attach to lwp %ld: %s (%d)\n", lwpid,
strerror (errno), errno);
fflush (stderr);
return;
}
/* If we fail to attach to a process, report an error. */
buffer_init (&buffer);
linux_ptrace_attach_warnings (lwpid, &buffer);
buffer_grow_str0 (&buffer, "");
error ("%sCannot attach to lwp %ld: %s (%d)", buffer_finish (&buffer),
lwpid, strerror (errno), errno);
}
if (initial)
/* If lwp is the tgid, we handle adding existing threads later.
Otherwise we just add lwp without bothering about any other
threads. */
ptid = ptid_build (lwpid, lwpid, 0);
else
{
/* Note that extracting the pid from the current inferior is
safe, since we're always called in the context of the same
process as this new thread. */
int pid = pid_of (get_thread_lwp (current_inferior));
ptid = ptid_build (pid, lwpid, 0);
}
new_lwp = (struct lwp_info *) add_lwp (ptid);
add_thread (ptid, new_lwp);
/* We need to wait for SIGSTOP before being able to make the next
ptrace call on this LWP. */
new_lwp->must_set_ptrace_flags = 1;
if (linux_proc_pid_is_stopped (lwpid))
{
if (debug_threads)
fprintf (stderr,
"Attached to a stopped process\n");
/* The process is definitely stopped. It is in a job control
stop, unless the kernel predates the TASK_STOPPED /
TASK_TRACED distinction, in which case it might be in a
ptrace stop. Make sure it is in a ptrace stop; from there we
can kill it, signal it, et cetera.
First make sure there is a pending SIGSTOP. Since we are
already attached, the process can not transition from stopped
to running without a PTRACE_CONT; so we know this signal will
go into the queue. The SIGSTOP generated by PTRACE_ATTACH is
probably already in the queue (unless this kernel is old
enough to use TASK_STOPPED for ptrace stops); but since
SIGSTOP is not an RT signal, it can only be queued once. */
kill_lwp (lwpid, SIGSTOP);
/* Finally, resume the stopped process. This will deliver the
SIGSTOP (or a higher priority signal, just like normal
PTRACE_ATTACH), which we'll catch later on. */
ptrace (PTRACE_CONT, lwpid, (PTRACE_ARG3_TYPE) 0, (PTRACE_ARG4_TYPE) 0);
}
/* The next time we wait for this LWP we'll see a SIGSTOP as PTRACE_ATTACH
brings it to a halt.
There are several cases to consider here:
1) gdbserver has already attached to the process and is being notified
of a new thread that is being created.
In this case we should ignore that SIGSTOP and resume the
process. This is handled below by setting stop_expected = 1,
and the fact that add_thread sets last_resume_kind ==
resume_continue.
2) This is the first thread (the process thread), and we're attaching
to it via attach_inferior.
In this case we want the process thread to stop.
This is handled by having linux_attach set last_resume_kind ==
resume_stop after we return.
If the pid we are attaching to is also the tgid, we attach to and
stop all the existing threads. Otherwise, we attach to pid and
ignore any other threads in the same group as this pid.
3) GDB is connecting to gdbserver and is requesting an enumeration of all
existing threads.
In this case we want the thread to stop.
FIXME: This case is currently not properly handled.
We should wait for the SIGSTOP but don't. Things work apparently
because enough time passes between when we ptrace (ATTACH) and when
gdb makes the next ptrace call on the thread.
On the other hand, if we are currently trying to stop all threads, we
should treat the new thread as if we had sent it a SIGSTOP. This works
because we are guaranteed that the add_lwp call above added us to the
end of the list, and so the new thread has not yet reached
wait_for_sigstop (but will). */
new_lwp->stop_expected = 1;
}
void
linux_attach_lwp (unsigned long lwpid)
{
linux_attach_lwp_1 (lwpid, 0);
}
/* Attach to PID. If PID is the tgid, attach to it and all
of its threads. */
static int
linux_attach (unsigned long pid)
{
/* Attach to PID. We will check for other threads
soon. */
linux_attach_lwp_1 (pid, 1);
linux_add_process (pid, 1);
if (!non_stop)
{
struct thread_info *thread;
/* Don't ignore the initial SIGSTOP if we just attached to this
process. It will be collected by wait shortly. */
thread = find_thread_ptid (ptid_build (pid, pid, 0));
thread->last_resume_kind = resume_stop;
}
if (linux_proc_get_tgid (pid) == pid)
{
DIR *dir;
char pathname[128];
sprintf (pathname, "/proc/%ld/task", pid);
dir = opendir (pathname);
if (!dir)
{
fprintf (stderr, "Could not open /proc/%ld/task.\n", pid);
fflush (stderr);
}
else
{
/* At this point we attached to the tgid. Scan the task for
existing threads. */
unsigned long lwp;
int new_threads_found;
int iterations = 0;
struct dirent *dp;
while (iterations < 2)
{
new_threads_found = 0;
/* Add all the other threads. While we go through the
threads, new threads may be spawned. Cycle through
the list of threads until we have done two iterations without
finding new threads. */
while ((dp = readdir (dir)) != NULL)
{
/* Fetch one lwp. */
lwp = strtoul (dp->d_name, NULL, 10);
/* Is this a new thread? */
if (lwp
&& find_thread_ptid (ptid_build (pid, lwp, 0)) == NULL)
{
linux_attach_lwp_1 (lwp, 0);
new_threads_found++;
if (debug_threads)
fprintf (stderr, "\
Found and attached to new lwp %ld\n", lwp);
}
}
if (!new_threads_found)
iterations++;
else
iterations = 0;
rewinddir (dir);
}
closedir (dir);
}
}
return 0;
}
struct counter
{
int pid;
int count;
};
static int
second_thread_of_pid_p (struct inferior_list_entry *entry, void *args)
{
struct counter *counter = args;
if (ptid_get_pid (entry->id) == counter->pid)
{
if (++counter->count > 1)
return 1;
}
return 0;
}
static int
last_thread_of_process_p (struct thread_info *thread)
{
ptid_t ptid = ((struct inferior_list_entry *)thread)->id;
int pid = ptid_get_pid (ptid);
struct counter counter = { pid , 0 };
return (find_inferior (&all_threads,
second_thread_of_pid_p, &counter) == NULL);
}
/* Kill LWP. */
static void
linux_kill_one_lwp (struct lwp_info *lwp)
{
int pid = lwpid_of (lwp);
/* PTRACE_KILL is unreliable. After stepping into a signal handler,
there is no signal context, and ptrace(PTRACE_KILL) (or
ptrace(PTRACE_CONT, SIGKILL), pretty much the same) acts like
ptrace(CONT, pid, 0,0) and just resumes the tracee. A better
alternative is to kill with SIGKILL. We only need one SIGKILL
per process, not one for each thread. But since we still support
linuxthreads, and we also support debugging programs using raw
clone without CLONE_THREAD, we send one for each thread. For
years, we used PTRACE_KILL only, so we're being a bit paranoid
about some old kernels where PTRACE_KILL might work better
(dubious if there are any such, but that's why it's paranoia), so
we try SIGKILL first, PTRACE_KILL second, and so we're fine
everywhere. */
errno = 0;
kill (pid, SIGKILL);
if (debug_threads)
fprintf (stderr,
"LKL: kill (SIGKILL) %s, 0, 0 (%s)\n",
target_pid_to_str (ptid_of (lwp)),
errno ? strerror (errno) : "OK");
errno = 0;
ptrace (PTRACE_KILL, pid, (PTRACE_ARG3_TYPE) 0, (PTRACE_ARG4_TYPE) 0);
if (debug_threads)
fprintf (stderr,
"LKL: PTRACE_KILL %s, 0, 0 (%s)\n",
target_pid_to_str (ptid_of (lwp)),
errno ? strerror (errno) : "OK");
}
/* Callback for `find_inferior'. Kills an lwp of a given process,
except the leader. */
static int
kill_one_lwp_callback (struct inferior_list_entry *entry, void *args)
{
struct thread_info *thread = (struct thread_info *) entry;
struct lwp_info *lwp = get_thread_lwp (thread);
int wstat;
int pid = * (int *) args;
if (ptid_get_pid (entry->id) != pid)
return 0;
/* We avoid killing the first thread here, because of a Linux kernel (at
least 2.6.0-test7 through 2.6.8-rc4) bug; if we kill the parent before
the children get a chance to be reaped, it will remain a zombie
forever. */
if (lwpid_of (lwp) == pid)
{
if (debug_threads)
fprintf (stderr, "lkop: is last of process %s\n",
target_pid_to_str (entry->id));
return 0;
}
do
{
linux_kill_one_lwp (lwp);
/* Make sure it died. The loop is most likely unnecessary. */
pid = linux_wait_for_event (lwp->head.id, &wstat, __WALL);
} while (pid > 0 && WIFSTOPPED (wstat));
return 0;
}
static int
linux_kill (int pid)
{
struct process_info *process;
struct lwp_info *lwp;
int wstat;
int lwpid;
process = find_process_pid (pid);
if (process == NULL)
return -1;
/* If we're killing a running inferior, make sure it is stopped
first, as PTRACE_KILL will not work otherwise. */
stop_all_lwps (0, NULL);
find_inferior (&all_threads, kill_one_lwp_callback , &pid);
/* See the comment in linux_kill_one_lwp. We did not kill the first
thread in the list, so do so now. */
lwp = find_lwp_pid (pid_to_ptid (pid));
if (lwp == NULL)
{
if (debug_threads)
fprintf (stderr, "lk_1: cannot find lwp %ld, for pid: %d\n",
lwpid_of (lwp), pid);
}
else
{
if (debug_threads)
fprintf (stderr, "lk_1: killing lwp %ld, for pid: %d\n",
lwpid_of (lwp), pid);
do
{
linux_kill_one_lwp (lwp);
/* Make sure it died. The loop is most likely unnecessary. */
lwpid = linux_wait_for_event (lwp->head.id, &wstat, __WALL);
} while (lwpid > 0 && WIFSTOPPED (wstat));
}
the_target->mourn (process);
/* Since we presently can only stop all lwps of all processes, we
need to unstop lwps of other processes. */
unstop_all_lwps (0, NULL);
return 0;
}
/* Get pending signal of THREAD, for detaching purposes. This is the
signal the thread last stopped for, which we need to deliver to the
thread when detaching, otherwise, it'd be suppressed/lost. */
static int
get_detach_signal (struct thread_info *thread)
{
enum gdb_signal signo = GDB_SIGNAL_0;
int status;
struct lwp_info *lp = get_thread_lwp (thread);
if (lp->status_pending_p)
status = lp->status_pending;
else
{
/* If the thread had been suspended by gdbserver, and it stopped
cleanly, then it'll have stopped with SIGSTOP. But we don't
want to deliver that SIGSTOP. */
if (thread->last_status.kind != TARGET_WAITKIND_STOPPED
|| thread->last_status.value.sig == GDB_SIGNAL_0)
return 0;
/* Otherwise, we may need to deliver the signal we
intercepted. */
status = lp->last_status;
}
if (!WIFSTOPPED (status))
{
if (debug_threads)
fprintf (stderr,
"GPS: lwp %s hasn't stopped: no pending signal\n",
target_pid_to_str (ptid_of (lp)));
return 0;
}
/* Extended wait statuses aren't real SIGTRAPs. */
if (WSTOPSIG (status) == SIGTRAP && status >> 16 != 0)
{
if (debug_threads)
fprintf (stderr,
"GPS: lwp %s had stopped with extended "
"status: no pending signal\n",
target_pid_to_str (ptid_of (lp)));
return 0;
}
signo = gdb_signal_from_host (WSTOPSIG (status));
if (program_signals_p && !program_signals[signo])
{
if (debug_threads)
fprintf (stderr,
"GPS: lwp %s had signal %s, but it is in nopass state\n",
target_pid_to_str (ptid_of (lp)),
gdb_signal_to_string (signo));
return 0;
}
else if (!program_signals_p
/* If we have no way to know which signals GDB does not
want to have passed to the program, assume
SIGTRAP/SIGINT, which is GDB's default. */
&& (signo == GDB_SIGNAL_TRAP || signo == GDB_SIGNAL_INT))
{
if (debug_threads)
fprintf (stderr,
"GPS: lwp %s had signal %s, "
"but we don't know if we should pass it. Default to not.\n",
target_pid_to_str (ptid_of (lp)),
gdb_signal_to_string (signo));
return 0;
}
else
{
if (debug_threads)
fprintf (stderr,
"GPS: lwp %s has pending signal %s: delivering it.\n",
target_pid_to_str (ptid_of (lp)),
gdb_signal_to_string (signo));
return WSTOPSIG (status);
}
}
static int
linux_detach_one_lwp (struct inferior_list_entry *entry, void *args)
{
struct thread_info *thread = (struct thread_info *) entry;
struct lwp_info *lwp = get_thread_lwp (thread);
int pid = * (int *) args;
int sig;
if (ptid_get_pid (entry->id) != pid)
return 0;
/* If there is a pending SIGSTOP, get rid of it. */
if (lwp->stop_expected)
{
if (debug_threads)
fprintf (stderr,
"Sending SIGCONT to %s\n",
target_pid_to_str (ptid_of (lwp)));
kill_lwp (lwpid_of (lwp), SIGCONT);
lwp->stop_expected = 0;
}
/* Flush any pending changes to the process's registers. */
regcache_invalidate_one ((struct inferior_list_entry *)
get_lwp_thread (lwp));
/* Pass on any pending signal for this thread. */
sig = get_detach_signal (thread);
/* Finally, let it resume. */
if (the_low_target.prepare_to_resume != NULL)
the_low_target.prepare_to_resume (lwp);
if (ptrace (PTRACE_DETACH, lwpid_of (lwp), (PTRACE_ARG3_TYPE) 0,
(PTRACE_ARG4_TYPE) (long) sig) < 0)
error (_("Can't detach %s: %s"),
target_pid_to_str (ptid_of (lwp)),
strerror (errno));
delete_lwp (lwp);
return 0;
}
static int
linux_detach (int pid)
{
struct process_info *process;
process = find_process_pid (pid);
if (process == NULL)
return -1;
/* Stop all threads before detaching. First, ptrace requires that
the thread is stopped to sucessfully detach. Second, thread_db
may need to uninstall thread event breakpoints from memory, which
only works with a stopped process anyway. */
stop_all_lwps (0, NULL);
#ifdef USE_THREAD_DB
thread_db_detach (process);
#endif
/* Stabilize threads (move out of jump pads). */
stabilize_threads ();
find_inferior (&all_threads, linux_detach_one_lwp, &pid);
the_target->mourn (process);
/* Since we presently can only stop all lwps of all processes, we
need to unstop lwps of other processes. */
unstop_all_lwps (0, NULL);
return 0;
}
/* Remove all LWPs that belong to process PROC from the lwp list. */
static int
delete_lwp_callback (struct inferior_list_entry *entry, void *proc)
{
struct lwp_info *lwp = (struct lwp_info *) entry;
struct process_info *process = proc;
if (pid_of (lwp) == pid_of (process))
delete_lwp (lwp);
return 0;
}
static void
linux_mourn (struct process_info *process)
{
struct process_info_private *priv;
#ifdef USE_THREAD_DB
thread_db_mourn (process);
#endif
find_inferior (&all_lwps, delete_lwp_callback, process);
/* Freeing all private data. */
priv = process->private;
free (priv->arch_private);
free (priv);
process->private = NULL;
remove_process (process);
}
static void
linux_join (int pid)
{
int status, ret;
do {
ret = my_waitpid (pid, &status, 0);
if (WIFEXITED (status) || WIFSIGNALED (status))
break;
} while (ret != -1 || errno != ECHILD);
}
/* Return nonzero if the given thread is still alive. */
static int
linux_thread_alive (ptid_t ptid)
{
struct lwp_info *lwp = find_lwp_pid (ptid);
/* We assume we always know if a thread exits. If a whole process
exited but we still haven't been able to report it to GDB, we'll
hold on to the last lwp of the dead process. */
if (lwp != NULL)
return !lwp->dead;
else
return 0;
}
/* Return 1 if this lwp has an interesting status pending. */
static int
status_pending_p_callback (struct inferior_list_entry *entry, void *arg)
{
struct lwp_info *lwp = (struct lwp_info *) entry;
ptid_t ptid = * (ptid_t *) arg;
struct thread_info *thread;
/* Check if we're only interested in events from a specific process
or its lwps. */
if (!ptid_equal (minus_one_ptid, ptid)
&& ptid_get_pid (ptid) != ptid_get_pid (lwp->head.id))
return 0;
thread = get_lwp_thread (lwp);
/* If we got a `vCont;t', but we haven't reported a stop yet, do
report any status pending the LWP may have. */
if (thread->last_resume_kind == resume_stop
&& thread->last_status.kind != TARGET_WAITKIND_IGNORE)
return 0;
return lwp->status_pending_p;
}
static int
same_lwp (struct inferior_list_entry *entry, void *data)
{
ptid_t ptid = *(ptid_t *) data;
int lwp;
if (ptid_get_lwp (ptid) != 0)
lwp = ptid_get_lwp (ptid);
else
lwp = ptid_get_pid (ptid);
if (ptid_get_lwp (entry->id) == lwp)
return 1;
return 0;
}
struct lwp_info *
find_lwp_pid (ptid_t ptid)
{
return (struct lwp_info*) find_inferior (&all_lwps, same_lwp, &ptid);
}
static struct lwp_info *
linux_wait_for_lwp (ptid_t ptid, int *wstatp, int options)
{
int ret;
int to_wait_for = -1;
struct lwp_info *child = NULL;
if (debug_threads)
fprintf (stderr, "linux_wait_for_lwp: %s\n", target_pid_to_str (ptid));
if (ptid_equal (ptid, minus_one_ptid))
to_wait_for = -1; /* any child */
else
to_wait_for = ptid_get_lwp (ptid); /* this lwp only */
options |= __WALL;
retry:
ret = my_waitpid (to_wait_for, wstatp, options);
if (ret == 0 || (ret == -1 && errno == ECHILD && (options & WNOHANG)))
return NULL;
else if (ret == -1)
perror_with_name ("waitpid");
if (debug_threads
&& (!WIFSTOPPED (*wstatp)
|| (WSTOPSIG (*wstatp) != 32
&& WSTOPSIG (*wstatp) != 33)))
fprintf (stderr, "Got an event from %d (%x)\n", ret, *wstatp);
child = find_lwp_pid (pid_to_ptid (ret));
/* If we didn't find a process, one of two things presumably happened:
- A process we started and then detached from has exited. Ignore it.
- A process we are controlling has forked and the new child's stop
was reported to us by the kernel. Save its PID. */
if (child == NULL && WIFSTOPPED (*wstatp))
{
add_to_pid_list (&stopped_pids, ret, *wstatp);
goto retry;
}
else if (child == NULL)
goto retry;
child->stopped = 1;
child->last_status = *wstatp;
/* Architecture-specific setup after inferior is running.
This needs to happen after we have attached to the inferior
and it is stopped for the first time, but before we access
any inferior registers. */
if (new_inferior)
{
the_low_target.arch_setup ();
#ifdef HAVE_LINUX_REGSETS
memset (disabled_regsets, 0, num_regsets);
#endif
new_inferior = 0;
}
/* Fetch the possibly triggered data watchpoint info and store it in
CHILD.
On some archs, like x86, that use debug registers to set
watchpoints, it's possible that the way to know which watched
address trapped, is to check the register that is used to select
which address to watch. Problem is, between setting the
watchpoint and reading back which data address trapped, the user
may change the set of watchpoints, and, as a consequence, GDB
changes the debug registers in the inferior. To avoid reading
back a stale stopped-data-address when that happens, we cache in
LP the fact that a watchpoint trapped, and the corresponding data
address, as soon as we see CHILD stop with a SIGTRAP. If GDB
changes the debug registers meanwhile, we have the cached data we
can rely on. */
if (WIFSTOPPED (*wstatp) && WSTOPSIG (*wstatp) == SIGTRAP)
{
if (the_low_target.stopped_by_watchpoint == NULL)
{
child->stopped_by_watchpoint = 0;
}
else
{
struct thread_info *saved_inferior;
saved_inferior = current_inferior;
current_inferior = get_lwp_thread (child);
child->stopped_by_watchpoint
= the_low_target.stopped_by_watchpoint ();
if (child->stopped_by_watchpoint)
{
if (the_low_target.stopped_data_address != NULL)
child->stopped_data_address
= the_low_target.stopped_data_address ();
else
child->stopped_data_address = 0;
}
current_inferior = saved_inferior;
}
}
/* Store the STOP_PC, with adjustment applied. This depends on the
architecture being defined already (so that CHILD has a valid
regcache), and on LAST_STATUS being set (to check for SIGTRAP or
not). */
if (WIFSTOPPED (*wstatp))
child->stop_pc = get_stop_pc (child);
if (debug_threads
&& WIFSTOPPED (*wstatp)
&& the_low_target.get_pc != NULL)
{
struct thread_info *saved_inferior = current_inferior;
struct regcache *regcache;
CORE_ADDR pc;
current_inferior = get_lwp_thread (child);
regcache = get_thread_regcache (current_inferior, 1);
pc = (*the_low_target.get_pc) (regcache);
fprintf (stderr, "linux_wait_for_lwp: pc is 0x%lx\n", (long) pc);
current_inferior = saved_inferior;
}
return child;
}
/* This function should only be called if the LWP got a SIGTRAP.
Handle any tracepoint steps or hits. Return true if a tracepoint
event was handled, 0 otherwise. */
static int
handle_tracepoints (struct lwp_info *lwp)
{
struct thread_info *tinfo = get_lwp_thread (lwp);
int tpoint_related_event = 0;
/* If this tracepoint hit causes a tracing stop, we'll immediately
uninsert tracepoints. To do this, we temporarily pause all
threads, unpatch away, and then unpause threads. We need to make
sure the unpausing doesn't resume LWP too. */
lwp->suspended++;
/* And we need to be sure that any all-threads-stopping doesn't try
to move threads out of the jump pads, as it could deadlock the
inferior (LWP could be in the jump pad, maybe even holding the
lock.) */
/* Do any necessary step collect actions. */
tpoint_related_event |= tracepoint_finished_step (tinfo, lwp->stop_pc);
tpoint_related_event |= handle_tracepoint_bkpts (tinfo, lwp->stop_pc);
/* See if we just hit a tracepoint and do its main collect
actions. */
tpoint_related_event |= tracepoint_was_hit (tinfo, lwp->stop_pc);
lwp->suspended--;
gdb_assert (lwp->suspended == 0);
gdb_assert (!stabilizing_threads || lwp->collecting_fast_tracepoint);
if (tpoint_related_event)
{
if (debug_threads)
fprintf (stderr, "got a tracepoint event\n");
return 1;
}
return 0;
}
/* Convenience wrapper. Returns true if LWP is presently collecting a
fast tracepoint. */
static int
linux_fast_tracepoint_collecting (struct lwp_info *lwp,
struct fast_tpoint_collect_status *status)
{
CORE_ADDR thread_area;
if (the_low_target.get_thread_area == NULL)
return 0;
/* Get the thread area address. This is used to recognize which
thread is which when tracing with the in-process agent library.
We don't read anything from the address, and treat it as opaque;
it's the address itself that we assume is unique per-thread. */
if ((*the_low_target.get_thread_area) (lwpid_of (lwp), &thread_area) == -1)
return 0;
return fast_tracepoint_collecting (thread_area, lwp->stop_pc, status);
}
/* The reason we resume in the caller, is because we want to be able
to pass lwp->status_pending as WSTAT, and we need to clear
status_pending_p before resuming, otherwise, linux_resume_one_lwp
refuses to resume. */
static int
maybe_move_out_of_jump_pad (struct lwp_info *lwp, int *wstat)
{
struct thread_info *saved_inferior;
saved_inferior = current_inferior;
current_inferior = get_lwp_thread (lwp);
if ((wstat == NULL
|| (WIFSTOPPED (*wstat) && WSTOPSIG (*wstat) != SIGTRAP))
&& supports_fast_tracepoints ()
&& agent_loaded_p ())
{
struct fast_tpoint_collect_status status;
int r;
if (debug_threads)
fprintf (stderr, "\
Checking whether LWP %ld needs to move out of the jump pad.\n",
lwpid_of (lwp));
r = linux_fast_tracepoint_collecting (lwp, &status);
if (wstat == NULL
|| (WSTOPSIG (*wstat) != SIGILL
&& WSTOPSIG (*wstat) != SIGFPE
&& WSTOPSIG (*wstat) != SIGSEGV
&& WSTOPSIG (*wstat) != SIGBUS))
{
lwp->collecting_fast_tracepoint = r;
if (r != 0)
{
if (r == 1 && lwp->exit_jump_pad_bkpt == NULL)
{
/* Haven't executed the original instruction yet.
Set breakpoint there, and wait till it's hit,
then single-step until exiting the jump pad. */
lwp->exit_jump_pad_bkpt
= set_breakpoint_at (status.adjusted_insn_addr, NULL);
}
if (debug_threads)
fprintf (stderr, "\
Checking whether LWP %ld needs to move out of the jump pad...it does\n",
lwpid_of (lwp));
current_inferior = saved_inferior;
return 1;
}
}
else
{
/* If we get a synchronous signal while collecting, *and*
while executing the (relocated) original instruction,
reset the PC to point at the tpoint address, before
reporting to GDB. Otherwise, it's an IPA lib bug: just
report the signal to GDB, and pray for the best. */
lwp->collecting_fast_tracepoint = 0;
if (r != 0
&& (status.adjusted_insn_addr <= lwp->stop_pc
&& lwp->stop_pc < status.adjusted_insn_addr_end))
{
siginfo_t info;
struct regcache *regcache;
/* The si_addr on a few signals references the address
of the faulting instruction. Adjust that as
well. */
if ((WSTOPSIG (*wstat) == SIGILL
|| WSTOPSIG (*wstat) == SIGFPE
|| WSTOPSIG (*wstat) == SIGBUS
|| WSTOPSIG (*wstat) == SIGSEGV)
&& ptrace (PTRACE_GETSIGINFO, lwpid_of (lwp),
(PTRACE_ARG3_TYPE) 0, &info) == 0
/* Final check just to make sure we don't clobber
the siginfo of non-kernel-sent signals. */
&& (uintptr_t) info.si_addr == lwp->stop_pc)
{
info.si_addr = (void *) (uintptr_t) status.tpoint_addr;
ptrace (PTRACE_SETSIGINFO, lwpid_of (lwp),
(PTRACE_ARG3_TYPE) 0, &info);
}
regcache = get_thread_regcache (get_lwp_thread (lwp), 1);
(*the_low_target.set_pc) (regcache, status.tpoint_addr);
lwp->stop_pc = status.tpoint_addr;
/* Cancel any fast tracepoint lock this thread was
holding. */
force_unlock_trace_buffer ();
}
if (lwp->exit_jump_pad_bkpt != NULL)
{
if (debug_threads)
fprintf (stderr,
"Cancelling fast exit-jump-pad: removing bkpt. "
"stopping all threads momentarily.\n");
stop_all_lwps (1, lwp);
cancel_breakpoints ();
delete_breakpoint (lwp->exit_jump_pad_bkpt);
lwp->exit_jump_pad_bkpt = NULL;
unstop_all_lwps (1, lwp);
gdb_assert (lwp->suspended >= 0);
}
}
}
if (debug_threads)
fprintf (stderr, "\
Checking whether LWP %ld needs to move out of the jump pad...no\n",
lwpid_of (lwp));
current_inferior = saved_inferior;
return 0;
}
/* Enqueue one signal in the "signals to report later when out of the
jump pad" list. */
static void
enqueue_one_deferred_signal (struct lwp_info *lwp, int *wstat)
{
struct pending_signals *p_sig;
if (debug_threads)
fprintf (stderr, "\
Deferring signal %d for LWP %ld.\n", WSTOPSIG (*wstat), lwpid_of (lwp));
if (debug_threads)
{
struct pending_signals *sig;
for (sig = lwp->pending_signals_to_report;
sig != NULL;
sig = sig->prev)
fprintf (stderr,
" Already queued %d\n",
sig->signal);
fprintf (stderr, " (no more currently queued signals)\n");
}
/* Don't enqueue non-RT signals if they are already in the deferred
queue. (SIGSTOP being the easiest signal to see ending up here
twice) */
if (WSTOPSIG (*wstat) < __SIGRTMIN)
{
struct pending_signals *sig;
for (sig = lwp->pending_signals_to_report;
sig != NULL;
sig = sig->prev)
{
if (sig->signal == WSTOPSIG (*wstat))
{
if (debug_threads)
fprintf (stderr,
"Not requeuing already queued non-RT signal %d"
" for LWP %ld\n",
sig->signal,
lwpid_of (lwp));
return;
}
}
}
p_sig = xmalloc (sizeof (*p_sig));
p_sig->prev = lwp->pending_signals_to_report;
p_sig->signal = WSTOPSIG (*wstat);
memset (&p_sig->info, 0, sizeof (siginfo_t));
ptrace (PTRACE_GETSIGINFO, lwpid_of (lwp), (PTRACE_ARG3_TYPE) 0,
&p_sig->info);
lwp->pending_signals_to_report = p_sig;
}
/* Dequeue one signal from the "signals to report later when out of
the jump pad" list. */
static int
dequeue_one_deferred_signal (struct lwp_info *lwp, int *wstat)
{
if (lwp->pending_signals_to_report != NULL)
{
struct pending_signals **p_sig;
p_sig = &lwp->pending_signals_to_report;
while ((*p_sig)->prev != NULL)
p_sig = &(*p_sig)->prev;
*wstat = W_STOPCODE ((*p_sig)->signal);
if ((*p_sig)->info.si_signo != 0)
ptrace (PTRACE_SETSIGINFO, lwpid_of (lwp), (PTRACE_ARG3_TYPE) 0,
&(*p_sig)->info);
free (*p_sig);
*p_sig = NULL;
if (debug_threads)
fprintf (stderr, "Reporting deferred signal %d for LWP %ld.\n",
WSTOPSIG (*wstat), lwpid_of (lwp));
if (debug_threads)
{
struct pending_signals *sig;
for (sig = lwp->pending_signals_to_report;
sig != NULL;
sig = sig->prev)
fprintf (stderr,
" Still queued %d\n",
sig->signal);
fprintf (stderr, " (no more queued signals)\n");
}
return 1;
}
return 0;
}
/* Arrange for a breakpoint to be hit again later. We don't keep the
SIGTRAP status and don't forward the SIGTRAP signal to the LWP. We
will handle the current event, eventually we will resume this LWP,
and this breakpoint will trap again. */
static int
cancel_breakpoint (struct lwp_info *lwp)
{
struct thread_info *saved_inferior;
/* There's nothing to do if we don't support breakpoints. */
if (!supports_breakpoints ())
return 0;
/* breakpoint_at reads from current inferior. */
saved_inferior = current_inferior;
current_inferior = get_lwp_thread (lwp);
if ((*the_low_target.breakpoint_at) (lwp->stop_pc))
{
if (debug_threads)
fprintf (stderr,
"CB: Push back breakpoint for %s\n",
target_pid_to_str (ptid_of (lwp)));
/* Back up the PC if necessary. */
if (the_low_target.decr_pc_after_break)
{
struct regcache *regcache
= get_thread_regcache (current_inferior, 1);
(*the_low_target.set_pc) (regcache, lwp->stop_pc);
}
current_inferior = saved_inferior;
return 1;
}
else
{
if (debug_threads)
fprintf (stderr,
"CB: No breakpoint found at %s for [%s]\n",
paddress (lwp->stop_pc),
target_pid_to_str (ptid_of (lwp)));
}
current_inferior = saved_inferior;
return 0;
}
/* When the event-loop is doing a step-over, this points at the thread
being stepped. */
ptid_t step_over_bkpt;
/* Wait for an event from child PID. If PID is -1, wait for any
child. Store the stop status through the status pointer WSTAT.
OPTIONS is passed to the waitpid call. Return 0 if no child stop
event was found and OPTIONS contains WNOHANG. Return the PID of
the stopped child otherwise. */
static int
linux_wait_for_event (ptid_t ptid, int *wstat, int options)
{
struct lwp_info *event_child, *requested_child;
ptid_t wait_ptid;
event_child = NULL;
requested_child = NULL;
/* Check for a lwp with a pending status. */
if (ptid_equal (ptid, minus_one_ptid) || ptid_is_pid (ptid))
{
event_child = (struct lwp_info *)
find_inferior (&all_lwps, status_pending_p_callback, &ptid);
if (debug_threads && event_child)
fprintf (stderr, "Got a pending child %ld\n", lwpid_of (event_child));
}
else
{
requested_child = find_lwp_pid (ptid);
if (stopping_threads == NOT_STOPPING_THREADS
&& requested_child->status_pending_p
&& requested_child->collecting_fast_tracepoint)
{
enqueue_one_deferred_signal (requested_child,
&requested_child->status_pending);
requested_child->status_pending_p = 0;
requested_child->status_pending = 0;
linux_resume_one_lwp (requested_child, 0, 0, NULL);
}
if (requested_child->suspended
&& requested_child->status_pending_p)
fatal ("requesting an event out of a suspended child?");
if (requested_child->status_pending_p)
event_child = requested_child;
}
if (event_child != NULL)
{
if (debug_threads)
fprintf (stderr, "Got an event from pending child %ld (%04x)\n",
lwpid_of (event_child), event_child->status_pending);
*wstat = event_child->status_pending;
event_child->status_pending_p = 0;
event_child->status_pending = 0;
current_inferior = get_lwp_thread (event_child);
return lwpid_of (event_child);
}
if (ptid_is_pid (ptid))
{
/* A request to wait for a specific tgid. This is not possible
with waitpid, so instead, we wait for any child, and leave
children we're not interested in right now with a pending
status to report later. */
wait_ptid = minus_one_ptid;
}
else
wait_ptid = ptid;
/* We only enter this loop if no process has a pending wait status. Thus
any action taken in response to a wait status inside this loop is
responding as soon as we detect the status, not after any pending
events. */
while (1)
{
event_child = linux_wait_for_lwp (wait_ptid, wstat, options);
if ((options & WNOHANG) && event_child == NULL)
{
if (debug_threads)
fprintf (stderr, "WNOHANG set, no event found\n");
return 0;
}
if (event_child == NULL)
error ("event from unknown child");
if (ptid_is_pid (ptid)
&& ptid_get_pid (ptid) != ptid_get_pid (ptid_of (event_child)))
{
if (! WIFSTOPPED (*wstat))
mark_lwp_dead (event_child, *wstat);
else
{
event_child->status_pending_p = 1;
event_child->status_pending = *wstat;
}
continue;
}
current_inferior = get_lwp_thread (event_child);
/* Check for thread exit. */
if (! WIFSTOPPED (*wstat))
{
if (debug_threads)
fprintf (stderr, "LWP %ld exiting\n", lwpid_of (event_child));
/* If the last thread is exiting, just return. */
if (last_thread_of_process_p (current_inferior))
{
if (debug_threads)
fprintf (stderr, "LWP %ld is last lwp of process\n",
lwpid_of (event_child));
return lwpid_of (event_child);
}
if (!non_stop)
{
current_inferior = (struct thread_info *) all_threads.head;
if (debug_threads)
fprintf (stderr, "Current inferior is now %ld\n",
lwpid_of (get_thread_lwp (current_inferior)));
}
else
{
current_inferior = NULL;
if (debug_threads)
fprintf (stderr, "Current inferior is now <NULL>\n");
}
/* If we were waiting for this particular child to do something...
well, it did something. */
if (requested_child != NULL)
{
int lwpid = lwpid_of (event_child);
/* Cancel the step-over operation --- the thread that
started it is gone. */
if (finish_step_over (event_child))
unstop_all_lwps (1, event_child);
delete_lwp (event_child);
return lwpid;
}
delete_lwp (event_child);
/* Wait for a more interesting event. */
continue;
}
if (event_child->must_set_ptrace_flags)
{
linux_enable_event_reporting (lwpid_of (event_child));
event_child->must_set_ptrace_flags = 0;
}
if (WIFSTOPPED (*wstat) && WSTOPSIG (*wstat) == SIGTRAP
&& *wstat >> 16 != 0)
{
handle_extended_wait (event_child, *wstat);
continue;
}
if (WIFSTOPPED (*wstat)
&& WSTOPSIG (*wstat) == SIGSTOP
&& event_child->stop_expected)
{
int should_stop;
if (debug_threads)
fprintf (stderr, "Expected stop.\n");
event_child->stop_expected = 0;
should_stop = (current_inferior->last_resume_kind == resume_stop
|| stopping_threads != NOT_STOPPING_THREADS);
if (!should_stop)
{
linux_resume_one_lwp (event_child,
event_child->stepping, 0, NULL);
continue;
}
}
return lwpid_of (event_child);
}
/* NOTREACHED */
return 0;
}
/* Count the LWP's that have had events. */
static int
count_events_callback (struct inferior_list_entry *entry, void *data)
{
struct lwp_info *lp = (struct lwp_info *) entry;
struct thread_info *thread = get_lwp_thread (lp);
int *count = data;
gdb_assert (count != NULL);
/* Count only resumed LWPs that have a SIGTRAP event pending that
should be reported to GDB. */
if (thread->last_status.kind == TARGET_WAITKIND_IGNORE
&& thread->last_resume_kind != resume_stop
&& lp->status_pending_p
&& WIFSTOPPED (lp->status_pending)
&& WSTOPSIG (lp->status_pending) == SIGTRAP
&& !breakpoint_inserted_here (lp->stop_pc))
(*count)++;
return 0;
}
/* Select the LWP (if any) that is currently being single-stepped. */
static int
select_singlestep_lwp_callback (struct inferior_list_entry *entry, void *data)
{
struct lwp_info *lp = (struct lwp_info *) entry;
struct thread_info *thread = get_lwp_thread (lp);
if (thread->last_status.kind == TARGET_WAITKIND_IGNORE
&& thread->last_resume_kind == resume_step
&& lp->status_pending_p)
return 1;
else
return 0;
}
/* Select the Nth LWP that has had a SIGTRAP event that should be
reported to GDB. */
static int
select_event_lwp_callback (struct inferior_list_entry *entry, void *data)
{
struct lwp_info *lp = (struct lwp_info *) entry;
struct thread_info *thread = get_lwp_thread (lp);
int *selector = data;
gdb_assert (selector != NULL);
/* Select only resumed LWPs that have a SIGTRAP event pending. */
if (thread->last_resume_kind != resume_stop
&& thread->last_status.kind == TARGET_WAITKIND_IGNORE
&& lp->status_pending_p
&& WIFSTOPPED (lp->status_pending)
&& WSTOPSIG (lp->status_pending) == SIGTRAP
&& !breakpoint_inserted_here (lp->stop_pc))
if ((*selector)-- == 0)
return 1;
return 0;
}
static int
cancel_breakpoints_callback (struct inferior_list_entry *entry, void *data)
{
struct lwp_info *lp = (struct lwp_info *) entry;
struct thread_info *thread = get_lwp_thread (lp);
struct lwp_info *event_lp = data;
/* Leave the LWP that has been elected to receive a SIGTRAP alone. */
if (lp == event_lp)
return 0;
/* If a LWP other than the LWP that we're reporting an event for has
hit a GDB breakpoint (as opposed to some random trap signal),
then just arrange for it to hit it again later. We don't keep
the SIGTRAP status and don't forward the SIGTRAP signal to the
LWP. We will handle the current event, eventually we will resume
all LWPs, and this one will get its breakpoint trap again.
If we do not do this, then we run the risk that the user will
delete or disable the breakpoint, but the LWP will have already
tripped on it. */
if (thread->last_resume_kind != resume_stop
&& thread->last_status.kind == TARGET_WAITKIND_IGNORE
&& lp->status_pending_p
&& WIFSTOPPED (lp->status_pending)
&& WSTOPSIG (lp->status_pending) == SIGTRAP
&& !lp->stepping
&& !lp->stopped_by_watchpoint
&& cancel_breakpoint (lp))
/* Throw away the SIGTRAP. */
lp->status_pending_p = 0;
return 0;
}
static void
linux_cancel_breakpoints (void)
{
find_inferior (&all_lwps, cancel_breakpoints_callback, NULL);
}
/* Select one LWP out of those that have events pending. */
static void
select_event_lwp (struct lwp_info **orig_lp)
{
int num_events = 0;
int random_selector;
struct lwp_info *event_lp;
/* Give preference to any LWP that is being single-stepped. */
event_lp
= (struct lwp_info *) find_inferior (&all_lwps,
select_singlestep_lwp_callback, NULL);
if (event_lp != NULL)
{
if (debug_threads)
fprintf (stderr,
"SEL: Select single-step %s\n",
target_pid_to_str (ptid_of (event_lp)));
}
else
{
/* No single-stepping LWP. Select one at random, out of those
which have had SIGTRAP events. */
/* First see how many SIGTRAP events we have. */
find_inferior (&all_lwps, count_events_callback, &num_events);
/* Now randomly pick a LWP out of those that have had a SIGTRAP. */
random_selector = (int)
((num_events * (double) rand ()) / (RAND_MAX + 1.0));
if (debug_threads && num_events > 1)
fprintf (stderr,
"SEL: Found %d SIGTRAP events, selecting #%d\n",
num_events, random_selector);
event_lp = (struct lwp_info *) find_inferior (&all_lwps,
select_event_lwp_callback,
&random_selector);
}
if (event_lp != NULL)
{
/* Switch the event LWP. */
*orig_lp = event_lp;
}
}
/* Decrement the suspend count of an LWP. */
static int
unsuspend_one_lwp (struct inferior_list_entry *entry, void *except)
{
struct lwp_info *lwp = (struct lwp_info *) entry;
/* Ignore EXCEPT. */
if (lwp == except)
return 0;
lwp->suspended--;
gdb_assert (lwp->suspended >= 0);
return 0;
}
/* Decrement the suspend count of all LWPs, except EXCEPT, if non
NULL. */
static void
unsuspend_all_lwps (struct lwp_info *except)
{
find_inferior (&all_lwps, unsuspend_one_lwp, except);
}
static void move_out_of_jump_pad_callback (struct inferior_list_entry *entry);
static int stuck_in_jump_pad_callback (struct inferior_list_entry *entry,
void *data);
static int lwp_running (struct inferior_list_entry *entry, void *data);
static ptid_t linux_wait_1 (ptid_t ptid,
struct target_waitstatus *ourstatus,
int target_options);
/* Stabilize threads (move out of jump pads).
If a thread is midway collecting a fast tracepoint, we need to
finish the collection and move it out of the jump pad before
reporting the signal.
This avoids recursion while collecting (when a signal arrives
midway, and the signal handler itself collects), which would trash
the trace buffer. In case the user set a breakpoint in a signal
handler, this avoids the backtrace showing the jump pad, etc..
Most importantly, there are certain things we can't do safely if
threads are stopped in a jump pad (or in its callee's). For
example:
- starting a new trace run. A thread still collecting the
previous run, could trash the trace buffer when resumed. The trace
buffer control structures would have been reset but the thread had
no way to tell. The thread could even midway memcpy'ing to the
buffer, which would mean that when resumed, it would clobber the
trace buffer that had been set for a new run.
- we can't rewrite/reuse the jump pads for new tracepoints
safely. Say you do tstart while a thread is stopped midway while
collecting. When the thread is later resumed, it finishes the
collection, and returns to the jump pad, to execute the original
instruction that was under the tracepoint jump at the time the
older run had been started. If the jump pad had been rewritten
since for something else in the new run, the thread would now
execute the wrong / random instructions. */
static void
linux_stabilize_threads (void)
{
struct thread_info *save_inferior;
struct lwp_info *lwp_stuck;
lwp_stuck
= (struct lwp_info *) find_inferior (&all_lwps,
stuck_in_jump_pad_callback, NULL);
if (lwp_stuck != NULL)
{
if (debug_threads)
fprintf (stderr, "can't stabilize, LWP %ld is stuck in jump pad\n",
lwpid_of (lwp_stuck));
return;
}
save_inferior = current_inferior;
stabilizing_threads = 1;
/* Kick 'em all. */
for_each_inferior (&all_lwps, move_out_of_jump_pad_callback);
/* Loop until all are stopped out of the jump pads. */
while (find_inferior (&all_lwps, lwp_running, NULL) != NULL)
{
struct target_waitstatus ourstatus;
struct lwp_info *lwp;
int wstat;
/* Note that we go through the full wait even loop. While
moving threads out of jump pad, we need to be able to step
over internal breakpoints and such. */
linux_wait_1 (minus_one_ptid, &ourstatus, 0);
if (ourstatus.kind == TARGET_WAITKIND_STOPPED)
{
lwp = get_thread_lwp (current_inferior);
/* Lock it. */
lwp->suspended++;
if (ourstatus.value.sig != GDB_SIGNAL_0
|| current_inferior->last_resume_kind == resume_stop)
{
wstat = W_STOPCODE (gdb_signal_to_host (ourstatus.value.sig));
enqueue_one_deferred_signal (lwp, &wstat);
}
}
}
find_inferior (&all_lwps, unsuspend_one_lwp, NULL);
stabilizing_threads = 0;
current_inferior = save_inferior;
if (debug_threads)
{
lwp_stuck
= (struct lwp_info *) find_inferior (&all_lwps,
stuck_in_jump_pad_callback, NULL);
if (lwp_stuck != NULL)
fprintf (stderr, "couldn't stabilize, LWP %ld got stuck in jump pad\n",
lwpid_of (lwp_stuck));
}
}
/* Wait for process, returns status. */
static ptid_t
linux_wait_1 (ptid_t ptid,
struct target_waitstatus *ourstatus, int target_options)
{
int w;
struct lwp_info *event_child;
int options;
int pid;
int step_over_finished;
int bp_explains_trap;
int maybe_internal_trap;
int report_to_gdb;
int trace_event;
/* Translate generic target options into linux options. */
options = __WALL;
if (target_options & TARGET_WNOHANG)
options |= WNOHANG;
retry:
bp_explains_trap = 0;
trace_event = 0;
ourstatus->kind = TARGET_WAITKIND_IGNORE;
/* If we were only supposed to resume one thread, only wait for
that thread - if it's still alive. If it died, however - which
can happen if we're coming from the thread death case below -
then we need to make sure we restart the other threads. We could
pick a thread at random or restart all; restarting all is less
arbitrary. */
if (!non_stop
&& !ptid_equal (cont_thread, null_ptid)
&& !ptid_equal (cont_thread, minus_one_ptid))
{
struct thread_info *thread;
thread = (struct thread_info *) find_inferior_id (&all_threads,
cont_thread);
/* No stepping, no signal - unless one is pending already, of course. */
if (thread == NULL)
{
struct thread_resume resume_info;
resume_info.thread = minus_one_ptid;
resume_info.kind = resume_continue;
resume_info.sig = 0;
linux_resume (&resume_info, 1);
}
else
ptid = cont_thread;
}
if (ptid_equal (step_over_bkpt, null_ptid))
pid = linux_wait_for_event (ptid, &w, options);
else
{
if (debug_threads)
fprintf (stderr, "step_over_bkpt set [%s], doing a blocking wait\n",
target_pid_to_str (step_over_bkpt));
pid = linux_wait_for_event (step_over_bkpt, &w, options & ~WNOHANG);
}
if (pid == 0) /* only if TARGET_WNOHANG */
return null_ptid;
event_child = get_thread_lwp (current_inferior);
/* If we are waiting for a particular child, and it exited,
linux_wait_for_event will return its exit status. Similarly if
the last child exited. If this is not the last child, however,
do not report it as exited until there is a 'thread exited' response
available in the remote protocol. Instead, just wait for another event.
This should be safe, because if the thread crashed we will already
have reported the termination signal to GDB; that should stop any
in-progress stepping operations, etc.
Report the exit status of the last thread to exit. This matches
LinuxThreads' behavior. */
if (last_thread_of_process_p (current_inferior))
{
if (WIFEXITED (w) || WIFSIGNALED (w))
{
if (WIFEXITED (w))
{
ourstatus->kind = TARGET_WAITKIND_EXITED;
ourstatus->value.integer = WEXITSTATUS (w);
if (debug_threads)
fprintf (stderr,
"\nChild exited with retcode = %x \n",
WEXITSTATUS (w));
}
else
{
ourstatus->kind = TARGET_WAITKIND_SIGNALLED;
ourstatus->value.sig = gdb_signal_from_host (WTERMSIG (w));
if (debug_threads)
fprintf (stderr,
"\nChild terminated with signal = %x \n",
WTERMSIG (w));
}
return ptid_of (event_child);
}
}
else
{
if (!WIFSTOPPED (w))
goto retry;
}
/* If this event was not handled before, and is not a SIGTRAP, we
report it. SIGILL and SIGSEGV are also treated as traps in case
a breakpoint is inserted at the current PC. If this target does
not support internal breakpoints at all, we also report the
SIGTRAP without further processing; it's of no concern to us. */
maybe_internal_trap
= (supports_breakpoints ()
&& (WSTOPSIG (w) == SIGTRAP
|| ((WSTOPSIG (w) == SIGILL
|| WSTOPSIG (w) == SIGSEGV)
&& (*the_low_target.breakpoint_at) (event_child->stop_pc))));
if (maybe_internal_trap)
{
/* Handle anything that requires bookkeeping before deciding to
report the event or continue waiting. */
/* First check if we can explain the SIGTRAP with an internal
breakpoint, or if we should possibly report the event to GDB.
Do this before anything that may remove or insert a
breakpoint. */
bp_explains_trap = breakpoint_inserted_here (event_child->stop_pc);
/* We have a SIGTRAP, possibly a step-over dance has just
finished. If so, tweak the state machine accordingly,
reinsert breakpoints and delete any reinsert (software
single-step) breakpoints. */
step_over_finished = finish_step_over (event_child);
/* Now invoke the callbacks of any internal breakpoints there. */
check_breakpoints (event_child->stop_pc);
/* Handle tracepoint data collecting. This may overflow the
trace buffer, and cause a tracing stop, removing
breakpoints. */
trace_event = handle_tracepoints (event_child);
if (bp_explains_trap)
{
/* If we stepped or ran into an internal breakpoint, we've
already handled it. So next time we resume (from this
PC), we should step over it. */
if (debug_threads)
fprintf (stderr, "Hit a gdbserver breakpoint.\n");
if (breakpoint_here (event_child->stop_pc))
event_child->need_step_over = 1;
}
}
else
{
/* We have some other signal, possibly a step-over dance was in
progress, and it should be cancelled too. */
step_over_finished = finish_step_over (event_child);
}
/* We have all the data we need. Either report the event to GDB, or
resume threads and keep waiting for more. */
/* If we're collecting a fast tracepoint, finish the collection and
move out of the jump pad before delivering a signal. See
linux_stabilize_threads. */
if (WIFSTOPPED (w)
&& WSTOPSIG (w) != SIGTRAP
&& supports_fast_tracepoints ()
&& agent_loaded_p ())
{
if (debug_threads)
fprintf (stderr,
"Got signal %d for LWP %ld. Check if we need "
"to defer or adjust it.\n",
WSTOPSIG (w), lwpid_of (event_child));
/* Allow debugging the jump pad itself. */
if (current_inferior->last_resume_kind != resume_step
&& maybe_move_out_of_jump_pad (event_child, &w))
{
enqueue_one_deferred_signal (event_child, &w);
if (debug_threads)
fprintf (stderr,
"Signal %d for LWP %ld deferred (in jump pad)\n",
WSTOPSIG (w), lwpid_of (event_child));
linux_resume_one_lwp (event_child, 0, 0, NULL);
goto retry;
}
}
if (event_child->collecting_fast_tracepoint)
{
if (debug_threads)
fprintf (stderr, "\
LWP %ld was trying to move out of the jump pad (%d). \
Check if we're already there.\n",
lwpid_of (event_child),
event_child->collecting_fast_tracepoint);
trace_event = 1;
event_child->collecting_fast_tracepoint
= linux_fast_tracepoint_collecting (event_child, NULL);
if (event_child->collecting_fast_tracepoint != 1)
{
/* No longer need this breakpoint. */
if (event_child->exit_jump_pad_bkpt != NULL)
{
if (debug_threads)
fprintf (stderr,
"No longer need exit-jump-pad bkpt; removing it."
"stopping all threads momentarily.\n");
/* Other running threads could hit this breakpoint.
We don't handle moribund locations like GDB does,
instead we always pause all threads when removing
breakpoints, so that any step-over or
decr_pc_after_break adjustment is always taken
care of while the breakpoint is still
inserted. */
stop_all_lwps (1, event_child);
cancel_breakpoints ();
delete_breakpoint (event_child->exit_jump_pad_bkpt);
event_child->exit_jump_pad_bkpt = NULL;
unstop_all_lwps (1, event_child);
gdb_assert (event_child->suspended >= 0);
}
}
if (event_child->collecting_fast_tracepoint == 0)
{
if (debug_threads)
fprintf (stderr,
"fast tracepoint finished "
"collecting successfully.\n");
/* We may have a deferred signal to report. */
if (dequeue_one_deferred_signal (event_child, &w))
{
if (debug_threads)
fprintf (stderr, "dequeued one signal.\n");
}
else
{
if (debug_threads)
fprintf (stderr, "no deferred signals.\n");
if (stabilizing_threads)
{
ourstatus->kind = TARGET_WAITKIND_STOPPED;
ourstatus->value.sig = GDB_SIGNAL_0;
return ptid_of (event_child);
}
}
}
}
/* Check whether GDB would be interested in this event. */
/* If GDB is not interested in this signal, don't stop other
threads, and don't report it to GDB. Just resume the inferior
right away. We do this for threading-related signals as well as
any that GDB specifically requested we ignore. But never ignore
SIGSTOP if we sent it ourselves, and do not ignore signals when
stepping - they may require special handling to skip the signal
handler. */
/* FIXME drow/2002-06-09: Get signal numbers from the inferior's
thread library? */
if (WIFSTOPPED (w)
&& current_inferior->last_resume_kind != resume_step
&& (
#if defined (USE_THREAD_DB) && !defined (__ANDROID__)
(current_process ()->private->thread_db != NULL
&& (WSTOPSIG (w) == __SIGRTMIN
|| WSTOPSIG (w) == __SIGRTMIN + 1))
||
#endif
(pass_signals[gdb_signal_from_host (WSTOPSIG (w))]
&& !(WSTOPSIG (w) == SIGSTOP
&& current_inferior->last_resume_kind == resume_stop))))
{
siginfo_t info, *info_p;
if (debug_threads)
fprintf (stderr, "Ignored signal %d for LWP %ld.\n",
WSTOPSIG (w), lwpid_of (event_child));
if (ptrace (PTRACE_GETSIGINFO, lwpid_of (event_child),
(PTRACE_ARG3_TYPE) 0, &info) == 0)
info_p = &info;
else
info_p = NULL;
linux_resume_one_lwp (event_child, event_child->stepping,
WSTOPSIG (w), info_p);
goto retry;
}
/* If GDB wanted this thread to single step, we always want to
report the SIGTRAP, and let GDB handle it. Watchpoints should
always be reported. So should signals we can't explain. A
SIGTRAP we can't explain could be a GDB breakpoint --- we may or
not support Z0 breakpoints. If we do, we're be able to handle
GDB breakpoints on top of internal breakpoints, by handling the
internal breakpoint and still reporting the event to GDB. If we
don't, we're out of luck, GDB won't see the breakpoint hit. */
report_to_gdb = (!maybe_internal_trap
|| current_inferior->last_resume_kind == resume_step
|| event_child->stopped_by_watchpoint
|| (!step_over_finished
&& !bp_explains_trap && !trace_event)
|| (gdb_breakpoint_here (event_child->stop_pc)
&& gdb_condition_true_at_breakpoint (event_child->stop_pc)
&& gdb_no_commands_at_breakpoint (event_child->stop_pc)));
run_breakpoint_commands (event_child->stop_pc);
/* We found no reason GDB would want us to stop. We either hit one
of our own breakpoints, or finished an internal step GDB
shouldn't know about. */
if (!report_to_gdb)
{
if (debug_threads)
{
if (bp_explains_trap)
fprintf (stderr, "Hit a gdbserver breakpoint.\n");
if (step_over_finished)
fprintf (stderr, "Step-over finished.\n");
if (trace_event)
fprintf (stderr, "Tracepoint event.\n");
}
/* We're not reporting this breakpoint to GDB, so apply the
decr_pc_after_break adjustment to the inferior's regcache
ourselves. */
if (the_low_target.set_pc != NULL)
{
struct regcache *regcache
= get_thread_regcache (get_lwp_thread (event_child), 1);
(*the_low_target.set_pc) (regcache, event_child->stop_pc);
}
/* We may have finished stepping over a breakpoint. If so,
we've stopped and suspended all LWPs momentarily except the
stepping one. This is where we resume them all again. We're
going to keep waiting, so use proceed, which handles stepping
over the next breakpoint. */
if (debug_threads)
fprintf (stderr, "proceeding all threads.\n");
if (step_over_finished)
unsuspend_all_lwps (event_child);
proceed_all_lwps ();
goto retry;
}
if (debug_threads)
{
if (current_inferior->last_resume_kind == resume_step)
fprintf (stderr, "GDB wanted to single-step, reporting event.\n");
if (event_child->stopped_by_watchpoint)
fprintf (stderr, "Stopped by watchpoint.\n");
if (gdb_breakpoint_here (event_child->stop_pc))
fprintf (stderr, "Stopped by GDB breakpoint.\n");
if (debug_threads)
fprintf (stderr, "Hit a non-gdbserver trap event.\n");
}
/* Alright, we're going to report a stop. */
if (!non_stop && !stabilizing_threads)
{
/* In all-stop, stop all threads. */
stop_all_lwps (0, NULL);
/* If we're not waiting for a specific LWP, choose an event LWP
from among those that have had events. Giving equal priority
to all LWPs that have had events helps prevent
starvation. */
if (ptid_equal (ptid, minus_one_ptid))
{
event_child->status_pending_p = 1;
event_child->status_pending = w;
select_event_lwp (&event_child);
event_child->status_pending_p = 0;
w = event_child->status_pending;
}
/* Now that we've selected our final event LWP, cancel any
breakpoints in other LWPs that have hit a GDB breakpoint.
See the comment in cancel_breakpoints_callback to find out
why. */
find_inferior (&all_lwps, cancel_breakpoints_callback, event_child);
/* If we were going a step-over, all other threads but the stepping one
had been paused in start_step_over, with their suspend counts
incremented. We don't want to do a full unstop/unpause, because we're
in all-stop mode (so we want threads stopped), but we still need to
unsuspend the other threads, to decrement their `suspended' count
back. */
if (step_over_finished)
unsuspend_all_lwps (event_child);
/* Stabilize threads (move out of jump pads). */
stabilize_threads ();
}
else
{
/* If we just finished a step-over, then all threads had been
momentarily paused. In all-stop, that's fine, we want
threads stopped by now anyway. In non-stop, we need to
re-resume threads that GDB wanted to be running. */
if (step_over_finished)
unstop_all_lwps (1, event_child);
}
ourstatus->kind = TARGET_WAITKIND_STOPPED;
if (current_inferior->last_resume_kind == resume_stop
&& WSTOPSIG (w) == SIGSTOP)
{
/* A thread that has been requested to stop by GDB with vCont;t,
and it stopped cleanly, so report as SIG0. The use of
SIGSTOP is an implementation detail. */
ourstatus->value.sig = GDB_SIGNAL_0;
}
else if (current_inferior->last_resume_kind == resume_stop
&& WSTOPSIG (w) != SIGSTOP)
{
/* A thread that has been requested to stop by GDB with vCont;t,
but, it stopped for other reasons. */
ourstatus->value.sig = gdb_signal_from_host (WSTOPSIG (w));
}
else
{
ourstatus->value.sig = gdb_signal_from_host (WSTOPSIG (w));
}
gdb_assert (ptid_equal (step_over_bkpt, null_ptid));
if (debug_threads)
fprintf (stderr, "linux_wait ret = %s, %d, %d\n",
target_pid_to_str (ptid_of (event_child)),
ourstatus->kind,
ourstatus->value.sig);
return ptid_of (event_child);
}
/* Get rid of any pending event in the pipe. */
static void
async_file_flush (void)
{
int ret;
char buf;
do
ret = read (linux_event_pipe[0], &buf, 1);
while (ret >= 0 || (ret == -1 && errno == EINTR));
}
/* Put something in the pipe, so the event loop wakes up. */
static void
async_file_mark (void)
{
int ret;
async_file_flush ();
do
ret = write (linux_event_pipe[1], "+", 1);
while (ret == 0 || (ret == -1 && errno == EINTR));
/* Ignore EAGAIN. If the pipe is full, the event loop will already
be awakened anyway. */
}
static ptid_t
linux_wait (ptid_t ptid,
struct target_waitstatus *ourstatus, int target_options)
{
ptid_t event_ptid;
if (debug_threads)
fprintf (stderr, "linux_wait: [%s]\n", target_pid_to_str (ptid));
/* Flush the async file first. */
if (target_is_async_p ())
async_file_flush ();
event_ptid = linux_wait_1 (ptid, ourstatus, target_options);
/* If at least one stop was reported, there may be more. A single
SIGCHLD can signal more than one child stop. */
if (target_is_async_p ()
&& (target_options & TARGET_WNOHANG) != 0
&& !ptid_equal (event_ptid, null_ptid))
async_file_mark ();
return event_ptid;
}
/* Send a signal to an LWP. */
static int
kill_lwp (unsigned long lwpid, int signo)
{
/* Use tkill, if possible, in case we are using nptl threads. If tkill
fails, then we are not using nptl threads and we should be using kill. */
#ifdef __NR_tkill
{
static int tkill_failed;
if (!tkill_failed)
{
int ret;
errno = 0;
ret = syscall (__NR_tkill, lwpid, signo);
if (errno != ENOSYS)
return ret;
tkill_failed = 1;
}
}
#endif
return kill (lwpid, signo);
}
void
linux_stop_lwp (struct lwp_info *lwp)
{
send_sigstop (lwp);
}
static void
send_sigstop (struct lwp_info *lwp)
{
int pid;
pid = lwpid_of (lwp);
/* If we already have a pending stop signal for this process, don't
send another. */
if (lwp->stop_expected)
{
if (debug_threads)
fprintf (stderr, "Have pending sigstop for lwp %d\n", pid);
return;
}
if (debug_threads)
fprintf (stderr, "Sending sigstop to lwp %d\n", pid);
lwp->stop_expected = 1;
kill_lwp (pid, SIGSTOP);
}
static int
send_sigstop_callback (struct inferior_list_entry *entry, void *except)
{
struct lwp_info *lwp = (struct lwp_info *) entry;
/* Ignore EXCEPT. */
if (lwp == except)
return 0;
if (lwp->stopped)
return 0;
send_sigstop (lwp);
return 0;
}
/* Increment the suspend count of an LWP, and stop it, if not stopped
yet. */
static int
suspend_and_send_sigstop_callback (struct inferior_list_entry *entry,
void *except)
{
struct lwp_info *lwp = (struct lwp_info *) entry;
/* Ignore EXCEPT. */
if (lwp == except)
return 0;
lwp->suspended++;
return send_sigstop_callback (entry, except);
}
static void
mark_lwp_dead (struct lwp_info *lwp, int wstat)
{
/* It's dead, really. */
lwp->dead = 1;
/* Store the exit status for later. */
lwp->status_pending_p = 1;
lwp->status_pending = wstat;
/* Prevent trying to stop it. */
lwp->stopped = 1;
/* No further stops are expected from a dead lwp. */
lwp->stop_expected = 0;
}
static void
wait_for_sigstop (struct inferior_list_entry *entry)
{
struct lwp_info *lwp = (struct lwp_info *) entry;
struct thread_info *saved_inferior;
int wstat;
ptid_t saved_tid;
ptid_t ptid;
int pid;
if (lwp->stopped)
{
if (debug_threads)
fprintf (stderr, "wait_for_sigstop: LWP %ld already stopped\n",
lwpid_of (lwp));
return;
}
saved_inferior = current_inferior;
if (saved_inferior != NULL)
saved_tid = ((struct inferior_list_entry *) saved_inferior)->id;
else
saved_tid = null_ptid; /* avoid bogus unused warning */
ptid = lwp->head.id;
if (debug_threads)
fprintf (stderr, "wait_for_sigstop: pulling one event\n");
pid = linux_wait_for_event (ptid, &wstat, __WALL);
/* If we stopped with a non-SIGSTOP signal, save it for later
and record the pending SIGSTOP. If the process exited, just
return. */
if (WIFSTOPPED (wstat))
{
if (debug_threads)
fprintf (stderr, "LWP %ld stopped with signal %d\n",
lwpid_of (lwp), WSTOPSIG (wstat));
if (WSTOPSIG (wstat) != SIGSTOP)
{
if (debug_threads)
fprintf (stderr, "LWP %ld stopped with non-sigstop status %06x\n",
lwpid_of (lwp), wstat);
lwp->status_pending_p = 1;
lwp->status_pending = wstat;
}
}
else
{
if (debug_threads)
fprintf (stderr, "Process %d exited while stopping LWPs\n", pid);
lwp = find_lwp_pid (pid_to_ptid (pid));
if (lwp)
{
/* Leave this status pending for the next time we're able to
report it. In the mean time, we'll report this lwp as
dead to GDB, so GDB doesn't try to read registers and
memory from it. This can only happen if this was the
last thread of the process; otherwise, PID is removed
from the thread tables before linux_wait_for_event
returns. */
mark_lwp_dead (lwp, wstat);
}
}
if (saved_inferior == NULL || linux_thread_alive (saved_tid))
current_inferior = saved_inferior;
else
{
if (debug_threads)
fprintf (stderr, "Previously current thread died.\n");
if (non_stop)
{
/* We can't change the current inferior behind GDB's back,
otherwise, a subsequent command may apply to the wrong
process. */
current_inferior = NULL;
}
else
{
/* Set a valid thread as current. */
set_desired_inferior (0);
}
}
}
/* Returns true if LWP ENTRY is stopped in a jump pad, and we can't
move it out, because we need to report the stop event to GDB. For
example, if the user puts a breakpoint in the jump pad, it's
because she wants to debug it. */
static int
stuck_in_jump_pad_callback (struct inferior_list_entry *entry, void *data)
{
struct lwp_info *lwp = (struct lwp_info *) entry;
struct thread_info *thread = get_lwp_thread (lwp);
gdb_assert (lwp->suspended == 0);
gdb_assert (lwp->stopped);
/* Allow debugging the jump pad, gdb_collect, etc.. */
return (supports_fast_tracepoints ()
&& agent_loaded_p ()
&& (gdb_breakpoint_here (lwp->stop_pc)
|| lwp->stopped_by_watchpoint
|| thread->last_resume_kind == resume_step)
&& linux_fast_tracepoint_collecting (lwp, NULL));
}
static void
move_out_of_jump_pad_callback (struct inferior_list_entry *entry)
{
struct lwp_info *lwp = (struct lwp_info *) entry;
struct thread_info *thread = get_lwp_thread (lwp);
int *wstat;
gdb_assert (lwp->suspended == 0);
gdb_assert (lwp->stopped);
wstat = lwp->status_pending_p ? &lwp->status_pending : NULL;
/* Allow debugging the jump pad, gdb_collect, etc. */
if (!gdb_breakpoint_here (lwp->stop_pc)
&& !lwp->stopped_by_watchpoint
&& thread->last_resume_kind != resume_step
&& maybe_move_out_of_jump_pad (lwp, wstat))
{
if (debug_threads)
fprintf (stderr,
"LWP %ld needs stabilizing (in jump pad)\n",
lwpid_of (lwp));
if (wstat)
{
lwp->status_pending_p = 0;
enqueue_one_deferred_signal (lwp, wstat);
if (debug_threads)
fprintf (stderr,
"Signal %d for LWP %ld deferred "
"(in jump pad)\n",
WSTOPSIG (*wstat), lwpid_of (lwp));
}
linux_resume_one_lwp (lwp, 0, 0, NULL);
}
else
lwp->suspended++;
}
static int
lwp_running (struct inferior_list_entry *entry, void *data)
{
struct lwp_info *lwp = (struct lwp_info *) entry;
if (lwp->dead)
return 0;
if (lwp->stopped)
return 0;
return 1;
}
/* Stop all lwps that aren't stopped yet, except EXCEPT, if not NULL.
If SUSPEND, then also increase the suspend count of every LWP,
except EXCEPT. */
static void
stop_all_lwps (int suspend, struct lwp_info *except)
{
/* Should not be called recursively. */
gdb_assert (stopping_threads == NOT_STOPPING_THREADS);
stopping_threads = (suspend
? STOPPING_AND_SUSPENDING_THREADS
: STOPPING_THREADS);
if (suspend)
find_inferior (&all_lwps, suspend_and_send_sigstop_callback, except);
else
find_inferior (&all_lwps, send_sigstop_callback, except);
for_each_inferior (&all_lwps, wait_for_sigstop);
stopping_threads = NOT_STOPPING_THREADS;
}
/* Resume execution of the inferior process.
If STEP is nonzero, single-step it.
If SIGNAL is nonzero, give it that signal. */
static void
linux_resume_one_lwp (struct lwp_info *lwp,
int step, int signal, siginfo_t *info)
{
struct thread_info *saved_inferior;
int fast_tp_collecting;
if (lwp->stopped == 0)
return;
fast_tp_collecting = lwp->collecting_fast_tracepoint;
gdb_assert (!stabilizing_threads || fast_tp_collecting);
/* Cancel actions that rely on GDB not changing the PC (e.g., the
user used the "jump" command, or "set $pc = foo"). */
if (lwp->stop_pc != get_pc (lwp))
{
/* Collecting 'while-stepping' actions doesn't make sense
anymore. */
release_while_stepping_state_list (get_lwp_thread (lwp));
}
/* If we have pending signals or status, and a new signal, enqueue the
signal. Also enqueue the signal if we are waiting to reinsert a
breakpoint; it will be picked up again below. */
if (signal != 0
&& (lwp->status_pending_p
|| lwp->pending_signals != NULL
|| lwp->bp_reinsert != 0
|| fast_tp_collecting))
{
struct pending_signals *p_sig;
p_sig = xmalloc (sizeof (*p_sig));
p_sig->prev = lwp->pending_signals;
p_sig->signal = signal;
if (info == NULL)
memset (&p_sig->info, 0, sizeof (siginfo_t));
else
memcpy (&p_sig->info, info, sizeof (siginfo_t));
lwp->pending_signals = p_sig;
}
if (lwp->status_pending_p)
{
if (debug_threads)
fprintf (stderr, "Not resuming lwp %ld (%s, signal %d, stop %s);"
" has pending status\n",
lwpid_of (lwp), step ? "step" : "continue", signal,
lwp->stop_expected ? "expected" : "not expected");
return;
}
saved_inferior = current_inferior;
current_inferior = get_lwp_thread (lwp);
if (debug_threads)
fprintf (stderr, "Resuming lwp %ld (%s, signal %d, stop %s)\n",
lwpid_of (lwp), step ? "step" : "continue", signal,
lwp->stop_expected ? "expected" : "not expected");
/* This bit needs some thinking about. If we get a signal that
we must report while a single-step reinsert is still pending,
we often end up resuming the thread. It might be better to
(ew) allow a stack of pending events; then we could be sure that
the reinsert happened right away and not lose any signals.
Making this stack would also shrink the window in which breakpoints are
uninserted (see comment in linux_wait_for_lwp) but not enough for
complete correctness, so it won't solve that problem. It may be
worthwhile just to solve this one, however. */
if (lwp->bp_reinsert != 0)
{
if (debug_threads)
fprintf (stderr, " pending reinsert at 0x%s\n",
paddress (lwp->bp_reinsert));
if (can_hardware_single_step ())
{
if (fast_tp_collecting == 0)
{
if (step == 0)
fprintf (stderr, "BAD - reinserting but not stepping.\n");
if (lwp->suspended)
fprintf (stderr, "BAD - reinserting and suspended(%d).\n",
lwp->suspended);
}
step = 1;
}
/* Postpone any pending signal. It was enqueued above. */
signal = 0;
}
if (fast_tp_collecting == 1)
{
if (debug_threads)
fprintf (stderr, "\
lwp %ld wants to get out of fast tracepoint jump pad (exit-jump-pad-bkpt)\n",
lwpid_of (lwp));
/* Postpone any pending signal. It was enqueued above. */
signal = 0;
}
else if (fast_tp_collecting == 2)
{
if (debug_threads)
fprintf (stderr, "\
lwp %ld wants to get out of fast tracepoint jump pad single-stepping\n",
lwpid_of (lwp));
if (can_hardware_single_step ())
step = 1;
else
fatal ("moving out of jump pad single-stepping"
" not implemented on this target");
/* Postpone any pending signal. It was enqueued above. */
signal = 0;
}
/* If we have while-stepping actions in this thread set it stepping.
If we have a signal to deliver, it may or may not be set to
SIG_IGN, we don't know. Assume so, and allow collecting
while-stepping into a signal handler. A possible smart thing to
do would be to set an internal breakpoint at the signal return
address, continue, and carry on catching this while-stepping
action only when that breakpoint is hit. A future
enhancement. */
if (get_lwp_thread (lwp)->while_stepping != NULL
&& can_hardware_single_step ())
{
if (debug_threads)
fprintf (stderr,
"lwp %ld has a while-stepping action -> forcing step.\n",
lwpid_of (lwp));
step = 1;
}
if (debug_threads && the_low_target.get_pc != NULL)
{
struct regcache *regcache = get_thread_regcache (current_inferior, 1);
CORE_ADDR pc = (*the_low_target.get_pc) (regcache);
fprintf (stderr, " resuming from pc 0x%lx\n", (long) pc);
}
/* If we have pending signals, consume one unless we are trying to
reinsert a breakpoint or we're trying to finish a fast tracepoint
collect. */
if (lwp->pending_signals != NULL
&& lwp->bp_reinsert == 0
&& fast_tp_collecting == 0)
{
struct pending_signals **p_sig;
p_sig = &lwp->pending_signals;
while ((*p_sig)->prev != NULL)
p_sig = &(*p_sig)->prev;
signal = (*p_sig)->signal;
if ((*p_sig)->info.si_signo != 0)
ptrace (PTRACE_SETSIGINFO, lwpid_of (lwp), (PTRACE_ARG3_TYPE) 0,
&(*p_sig)->info);
free (*p_sig);
*p_sig = NULL;
}
if (the_low_target.prepare_to_resume != NULL)
the_low_target.prepare_to_resume (lwp);
regcache_invalidate_one ((struct inferior_list_entry *)
get_lwp_thread (lwp));
errno = 0;
lwp->stopped = 0;
lwp->stopped_by_watchpoint = 0;
lwp->stepping = step;
ptrace (step ? PTRACE_SINGLESTEP : PTRACE_CONT, lwpid_of (lwp),
(PTRACE_ARG3_TYPE) 0,
/* Coerce to a uintptr_t first to avoid potential gcc warning
of coercing an 8 byte integer to a 4 byte pointer. */
(PTRACE_ARG4_TYPE) (uintptr_t) signal);
current_inferior = saved_inferior;
if (errno)
{
/* ESRCH from ptrace either means that the thread was already
running (an error) or that it is gone (a race condition). If
it's gone, we will get a notification the next time we wait,
so we can ignore the error. We could differentiate these
two, but it's tricky without waiting; the thread still exists
as a zombie, so sending it signal 0 would succeed. So just
ignore ESRCH. */
if (errno == ESRCH)
return;
perror_with_name ("ptrace");
}
}
struct thread_resume_array
{
struct thread_resume *resume;
size_t n;
};
/* This function is called once per thread. We look up the thread
in RESUME_PTR, and mark the thread with a pointer to the appropriate
resume request.
This algorithm is O(threads * resume elements), but resume elements
is small (and will remain small at least until GDB supports thread
suspension). */
static int
linux_set_resume_request (struct inferior_list_entry *entry, void *arg)
{
struct lwp_info *lwp;
struct thread_info *thread;
int ndx;
struct thread_resume_array *r;
thread = (struct thread_info *) entry;
lwp = get_thread_lwp (thread);
r = arg;
for (ndx = 0; ndx < r->n; ndx++)
{
ptid_t ptid = r->resume[ndx].thread;
if (ptid_equal (ptid, minus_one_ptid)
|| ptid_equal (ptid, entry->id)
/* Handle both 'pPID' and 'pPID.-1' as meaning 'all threads
of PID'. */
|| (ptid_get_pid (ptid) == pid_of (lwp)
&& (ptid_is_pid (ptid)
|| ptid_get_lwp (ptid) == -1)))
{
if (r->resume[ndx].kind == resume_stop
&& thread->last_resume_kind == resume_stop)
{
if (debug_threads)
fprintf (stderr, "already %s LWP %ld at GDB's request\n",
thread->last_status.kind == TARGET_WAITKIND_STOPPED
? "stopped"
: "stopping",
lwpid_of (lwp));
continue;
}
lwp->resume = &r->resume[ndx];
thread->last_resume_kind = lwp->resume->kind;
/* If we had a deferred signal to report, dequeue one now.
This can happen if LWP gets more than one signal while
trying to get out of a jump pad. */
if (lwp->stopped
&& !lwp->status_pending_p
&& dequeue_one_deferred_signal (lwp, &lwp->status_pending))
{
lwp->status_pending_p = 1;
if (debug_threads)
fprintf (stderr,
"Dequeueing deferred signal %d for LWP %ld, "
"leaving status pending.\n",
WSTOPSIG (lwp->status_pending), lwpid_of (lwp));
}
return 0;
}
}
/* No resume action for this thread. */
lwp->resume = NULL;
return 0;
}
/* Set *FLAG_P if this lwp has an interesting status pending. */
static int
resume_status_pending_p (struct inferior_list_entry *entry, void *flag_p)
{
struct lwp_info *lwp = (struct lwp_info *) entry;
/* LWPs which will not be resumed are not interesting, because
we might not wait for them next time through linux_wait. */
if (lwp->resume == NULL)
return 0;
if (lwp->status_pending_p)
* (int *) flag_p = 1;
return 0;
}
/* Return 1 if this lwp that GDB wants running is stopped at an
internal breakpoint that we need to step over. It assumes that any
required STOP_PC adjustment has already been propagated to the
inferior's regcache. */
static int
need_step_over_p (struct inferior_list_entry *entry, void *dummy)
{
struct lwp_info *lwp = (struct lwp_info *) entry;
struct thread_info *thread;
struct thread_info *saved_inferior;
CORE_ADDR pc;
/* LWPs which will not be resumed are not interesting, because we
might not wait for them next time through linux_wait. */
if (!lwp->stopped)
{
if (debug_threads)
fprintf (stderr,
"Need step over [LWP %ld]? Ignoring, not stopped\n",
lwpid_of (lwp));
return 0;
}
thread = get_lwp_thread (lwp);
if (thread->last_resume_kind == resume_stop)
{
if (debug_threads)
fprintf (stderr,
"Need step over [LWP %ld]? Ignoring, should remain stopped\n",
lwpid_of (lwp));
return 0;
}
gdb_assert (lwp->suspended >= 0);
if (lwp->suspended)
{
if (debug_threads)
fprintf (stderr,
"Need step over [LWP %ld]? Ignoring, suspended\n",
lwpid_of (lwp));
return 0;
}
if (!lwp->need_step_over)
{
if (debug_threads)
fprintf (stderr,
"Need step over [LWP %ld]? No\n", lwpid_of (lwp));
}
if (lwp->status_pending_p)
{
if (debug_threads)
fprintf (stderr,
"Need step over [LWP %ld]? Ignoring, has pending status.\n",
lwpid_of (lwp));
return 0;
}
/* Note: PC, not STOP_PC. Either GDB has adjusted the PC already,
or we have. */
pc = get_pc (lwp);
/* If the PC has changed since we stopped, then don't do anything,
and let the breakpoint/tracepoint be hit. This happens if, for
instance, GDB handled the decr_pc_after_break subtraction itself,
GDB is OOL stepping this thread, or the user has issued a "jump"
command, or poked thread's registers herself. */
if (pc != lwp->stop_pc)
{
if (debug_threads)
fprintf (stderr,
"Need step over [LWP %ld]? Cancelling, PC was changed. "
"Old stop_pc was 0x%s, PC is now 0x%s\n",
lwpid_of (lwp), paddress (lwp->stop_pc), paddress (pc));
lwp->need_step_over = 0;
return 0;
}
saved_inferior = current_inferior;
current_inferior = thread;
/* We can only step over breakpoints we know about. */
if (breakpoint_here (pc) || fast_tracepoint_jump_here (pc))
{
/* Don't step over a breakpoint that GDB expects to hit
though. If the condition is being evaluated on the target's side
and it evaluate to false, step over this breakpoint as well. */
if (gdb_breakpoint_here (pc)
&& gdb_condition_true_at_breakpoint (pc)
&& gdb_no_commands_at_breakpoint (pc))
{
if (debug_threads)
fprintf (stderr,
"Need step over [LWP %ld]? yes, but found"
" GDB breakpoint at 0x%s; skipping step over\n",
lwpid_of (lwp), paddress (pc));
current_inferior = saved_inferior;
return 0;
}
else
{
if (debug_threads)
fprintf (stderr,
"Need step over [LWP %ld]? yes, "
"found breakpoint at 0x%s\n",
lwpid_of (lwp), paddress (pc));
/* We've found an lwp that needs stepping over --- return 1 so
that find_inferior stops looking. */
current_inferior = saved_inferior;
/* If the step over is cancelled, this is set again. */
lwp->need_step_over = 0;
return 1;
}
}
current_inferior = saved_inferior;
if (debug_threads)
fprintf (stderr,
"Need step over [LWP %ld]? No, no breakpoint found at 0x%s\n",
lwpid_of (lwp), paddress (pc));
return 0;
}
/* Start a step-over operation on LWP. When LWP stopped at a
breakpoint, to make progress, we need to remove the breakpoint out
of the way. If we let other threads run while we do that, they may
pass by the breakpoint location and miss hitting it. To avoid
that, a step-over momentarily stops all threads while LWP is
single-stepped while the breakpoint is temporarily uninserted from
the inferior. When the single-step finishes, we reinsert the
breakpoint, and let all threads that are supposed to be running,
run again.
On targets that don't support hardware single-step, we don't
currently support full software single-stepping. Instead, we only
support stepping over the thread event breakpoint, by asking the
low target where to place a reinsert breakpoint. Since this
routine assumes the breakpoint being stepped over is a thread event
breakpoint, it usually assumes the return address of the current
function is a good enough place to set the reinsert breakpoint. */
static int
start_step_over (struct lwp_info *lwp)
{
struct thread_info *saved_inferior;
CORE_ADDR pc;
int step;
if (debug_threads)
fprintf (stderr,
"Starting step-over on LWP %ld. Stopping all threads\n",
lwpid_of (lwp));
stop_all_lwps (1, lwp);
gdb_assert (lwp->suspended == 0);
if (debug_threads)
fprintf (stderr, "Done stopping all threads for step-over.\n");
/* Note, we should always reach here with an already adjusted PC,
either by GDB (if we're resuming due to GDB's request), or by our
caller, if we just finished handling an internal breakpoint GDB
shouldn't care about. */
pc = get_pc (lwp);
saved_inferior = current_inferior;
current_inferior = get_lwp_thread (lwp);
lwp->bp_reinsert = pc;
uninsert_breakpoints_at (pc);
uninsert_fast_tracepoint_jumps_at (pc);
if (can_hardware_single_step ())
{
step = 1;
}
else
{
CORE_ADDR raddr = (*the_low_target.breakpoint_reinsert_addr) ();
set_reinsert_breakpoint (raddr);
step = 0;
}
current_inferior = saved_inferior;
linux_resume_one_lwp (lwp, step, 0, NULL);
/* Require next event from this LWP. */
step_over_bkpt = lwp->head.id;
return 1;
}
/* Finish a step-over. Reinsert the breakpoint we had uninserted in
start_step_over, if still there, and delete any reinsert
breakpoints we've set, on non hardware single-step targets. */
static int
finish_step_over (struct lwp_info *lwp)
{
if (lwp->bp_reinsert != 0)
{
if (debug_threads)
fprintf (stderr, "Finished step over.\n");
/* Reinsert any breakpoint at LWP->BP_REINSERT. Note that there
may be no breakpoint to reinsert there by now. */
reinsert_breakpoints_at (lwp->bp_reinsert);
reinsert_fast_tracepoint_jumps_at (lwp->bp_reinsert);
lwp->bp_reinsert = 0;
/* Delete any software-single-step reinsert breakpoints. No
longer needed. We don't have to worry about other threads
hitting this trap, and later not being able to explain it,
because we were stepping over a breakpoint, and we hold all
threads but LWP stopped while doing that. */
if (!can_hardware_single_step ())
delete_reinsert_breakpoints ();
step_over_bkpt = null_ptid;
return 1;
}
else
return 0;
}
/* This function is called once per thread. We check the thread's resume
request, which will tell us whether to resume, step, or leave the thread
stopped; and what signal, if any, it should be sent.
For threads which we aren't explicitly told otherwise, we preserve
the stepping flag; this is used for stepping over gdbserver-placed
breakpoints.
If pending_flags was set in any thread, we queue any needed
signals, since we won't actually resume. We already have a pending
event to report, so we don't need to preserve any step requests;
they should be re-issued if necessary. */
static int
linux_resume_one_thread (struct inferior_list_entry *entry, void *arg)
{
struct lwp_info *lwp;
struct thread_info *thread;
int step;
int leave_all_stopped = * (int *) arg;
int leave_pending;
thread = (struct thread_info *) entry;
lwp = get_thread_lwp (thread);
if (lwp->resume == NULL)
return 0;
if (lwp->resume->kind == resume_stop)
{
if (debug_threads)
fprintf (stderr, "resume_stop request for LWP %ld\n", lwpid_of (lwp));
if (!lwp->stopped)
{
if (debug_threads)
fprintf (stderr, "stopping LWP %ld\n", lwpid_of (lwp));
/* Stop the thread, and wait for the event asynchronously,
through the event loop. */
send_sigstop (lwp);
}
else
{
if (debug_threads)
fprintf (stderr, "already stopped LWP %ld\n",
lwpid_of (lwp));
/* The LWP may have been stopped in an internal event that
was not meant to be notified back to GDB (e.g., gdbserver
breakpoint), so we should be reporting a stop event in
this case too. */
/* If the thread already has a pending SIGSTOP, this is a
no-op. Otherwise, something later will presumably resume
the thread and this will cause it to cancel any pending
operation, due to last_resume_kind == resume_stop. If
the thread already has a pending status to report, we
will still report it the next time we wait - see
status_pending_p_callback. */
/* If we already have a pending signal to report, then
there's no need to queue a SIGSTOP, as this means we're
midway through moving the LWP out of the jumppad, and we
will report the pending signal as soon as that is
finished. */
if (lwp->pending_signals_to_report == NULL)
send_sigstop (lwp);
}
/* For stop requests, we're done. */
lwp->resume = NULL;
thread->last_status.kind = TARGET_WAITKIND_IGNORE;
return 0;
}
/* If this thread which is about to be resumed has a pending status,
then don't resume any threads - we can just report the pending
status. Make sure to queue any signals that would otherwise be
sent. In all-stop mode, we do this decision based on if *any*
thread has a pending status. If there's a thread that needs the
step-over-breakpoint dance, then don't resume any other thread
but that particular one. */
leave_pending = (lwp->status_pending_p || leave_all_stopped);
if (!leave_pending)
{
if (debug_threads)
fprintf (stderr, "resuming LWP %ld\n", lwpid_of (lwp));
step = (lwp->resume->kind == resume_step);
linux_resume_one_lwp (lwp, step, lwp->resume->sig, NULL);
}
else
{
if (debug_threads)
fprintf (stderr, "leaving LWP %ld stopped\n", lwpid_of (lwp));
/* If we have a new signal, enqueue the signal. */
if (lwp->resume->sig != 0)
{
struct pending_signals *p_sig;
p_sig = xmalloc (sizeof (*p_sig));
p_sig->prev = lwp->pending_signals;
p_sig->signal = lwp->resume->sig;
memset (&p_sig->info, 0, sizeof (siginfo_t));
/* If this is the same signal we were previously stopped by,
make sure to queue its siginfo. We can ignore the return
value of ptrace; if it fails, we'll skip
PTRACE_SETSIGINFO. */
if (WIFSTOPPED (lwp->last_status)
&& WSTOPSIG (lwp->last_status) == lwp->resume->sig)
ptrace (PTRACE_GETSIGINFO, lwpid_of (lwp), (PTRACE_ARG3_TYPE) 0,
&p_sig->info);
lwp->pending_signals = p_sig;
}
}
thread->last_status.kind = TARGET_WAITKIND_IGNORE;
lwp->resume = NULL;
return 0;
}
static void
linux_resume (struct thread_resume *resume_info, size_t n)
{
struct thread_resume_array array = { resume_info, n };
struct lwp_info *need_step_over = NULL;
int any_pending;
int leave_all_stopped;
find_inferior (&all_threads, linux_set_resume_request, &array);
/* If there is a thread which would otherwise be resumed, which has
a pending status, then don't resume any threads - we can just
report the pending status. Make sure to queue any signals that
would otherwise be sent. In non-stop mode, we'll apply this
logic to each thread individually. We consume all pending events
before considering to start a step-over (in all-stop). */
any_pending = 0;
if (!non_stop)
find_inferior (&all_lwps, resume_status_pending_p, &any_pending);
/* If there is a thread which would otherwise be resumed, which is
stopped at a breakpoint that needs stepping over, then don't
resume any threads - have it step over the breakpoint with all
other threads stopped, then resume all threads again. Make sure
to queue any signals that would otherwise be delivered or
queued. */
if (!any_pending && supports_breakpoints ())
need_step_over
= (struct lwp_info *) find_inferior (&all_lwps,
need_step_over_p, NULL);
leave_all_stopped = (need_step_over != NULL || any_pending);
if (debug_threads)
{
if (need_step_over != NULL)
fprintf (stderr, "Not resuming all, need step over\n");
else if (any_pending)
fprintf (stderr,
"Not resuming, all-stop and found "
"an LWP with pending status\n");
else
fprintf (stderr, "Resuming, no pending status or step over needed\n");
}
/* Even if we're leaving threads stopped, queue all signals we'd
otherwise deliver. */
find_inferior (&all_threads, linux_resume_one_thread, &leave_all_stopped);
if (need_step_over)
start_step_over (need_step_over);
}
/* This function is called once per thread. We check the thread's
last resume request, which will tell us whether to resume, step, or
leave the thread stopped. Any signal the client requested to be
delivered has already been enqueued at this point.
If any thread that GDB wants running is stopped at an internal
breakpoint that needs stepping over, we start a step-over operation
on that particular thread, and leave all others stopped. */
static int
proceed_one_lwp (struct inferior_list_entry *entry, void *except)
{
struct lwp_info *lwp = (struct lwp_info *) entry;
struct thread_info *thread;
int step;
if (lwp == except)
return 0;
if (debug_threads)
fprintf (stderr,
"proceed_one_lwp: lwp %ld\n", lwpid_of (lwp));
if (!lwp->stopped)
{
if (debug_threads)
fprintf (stderr, " LWP %ld already running\n", lwpid_of (lwp));
return 0;
}
thread = get_lwp_thread (lwp);
if (thread->last_resume_kind == resume_stop
&& thread->last_status.kind != TARGET_WAITKIND_IGNORE)
{
if (debug_threads)
fprintf (stderr, " client wants LWP to remain %ld stopped\n",
lwpid_of (lwp));
return 0;
}
if (lwp->status_pending_p)
{
if (debug_threads)
fprintf (stderr, " LWP %ld has pending status, leaving stopped\n",
lwpid_of (lwp));
return 0;
}
gdb_assert (lwp->suspended >= 0);
if (lwp->suspended)
{
if (debug_threads)
fprintf (stderr, " LWP %ld is suspended\n", lwpid_of (lwp));
return 0;
}
if (thread->last_resume_kind == resume_stop
&& lwp->pending_signals_to_report == NULL
&& lwp->collecting_fast_tracepoint == 0)
{
/* We haven't reported this LWP as stopped yet (otherwise, the
last_status.kind check above would catch it, and we wouldn't
reach here. This LWP may have been momentarily paused by a
stop_all_lwps call while handling for example, another LWP's
step-over. In that case, the pending expected SIGSTOP signal
that was queued at vCont;t handling time will have already
been consumed by wait_for_sigstop, and so we need to requeue
another one here. Note that if the LWP already has a SIGSTOP
pending, this is a no-op. */
if (debug_threads)
fprintf (stderr,
"Client wants LWP %ld to stop. "
"Making sure it has a SIGSTOP pending\n",
lwpid_of (lwp));
send_sigstop (lwp);
}
step = thread->last_resume_kind == resume_step;
linux_resume_one_lwp (lwp, step, 0, NULL);
return 0;
}
static int
unsuspend_and_proceed_one_lwp (struct inferior_list_entry *entry, void *except)
{
struct lwp_info *lwp = (struct lwp_info *) entry;
if (lwp == except)
return 0;
lwp->suspended--;
gdb_assert (lwp->suspended >= 0);
return proceed_one_lwp (entry, except);
}
/* When we finish a step-over, set threads running again. If there's
another thread that may need a step-over, now's the time to start
it. Eventually, we'll move all threads past their breakpoints. */
static void
proceed_all_lwps (void)
{
struct lwp_info *need_step_over;
/* If there is a thread which would otherwise be resumed, which is
stopped at a breakpoint that needs stepping over, then don't
resume any threads - have it step over the breakpoint with all
other threads stopped, then resume all threads again. */
if (supports_breakpoints ())
{
need_step_over
= (struct lwp_info *) find_inferior (&all_lwps,
need_step_over_p, NULL);
if (need_step_over != NULL)
{
if (debug_threads)
fprintf (stderr, "proceed_all_lwps: found "
"thread %ld needing a step-over\n",
lwpid_of (need_step_over));
start_step_over (need_step_over);
return;
}
}
if (debug_threads)
fprintf (stderr, "Proceeding, no step-over needed\n");
find_inferior (&all_lwps, proceed_one_lwp, NULL);
}
/* Stopped LWPs that the client wanted to be running, that don't have
pending statuses, are set to run again, except for EXCEPT, if not
NULL. This undoes a stop_all_lwps call. */
static void
unstop_all_lwps (int unsuspend, struct lwp_info *except)
{
if (debug_threads)
{
if (except)
fprintf (stderr,
"unstopping all lwps, except=(LWP %ld)\n", lwpid_of (except));
else
fprintf (stderr,
"unstopping all lwps\n");
}
if (unsuspend)
find_inferior (&all_lwps, unsuspend_and_proceed_one_lwp, except);
else
find_inferior (&all_lwps, proceed_one_lwp, except);
}
#ifdef HAVE_LINUX_REGSETS
#define use_linux_regsets 1
static int
regsets_fetch_inferior_registers (struct regcache *regcache)
{
struct regset_info *regset;
int saw_general_regs = 0;
int pid;
struct iovec iov;
regset = target_regsets;
pid = lwpid_of (get_thread_lwp (current_inferior));
while (regset->size >= 0)
{
void *buf, *data;
int nt_type, res;
if (regset->size == 0 || disabled_regsets[regset - target_regsets])
{
regset ++;
continue;
}
buf = xmalloc (regset->size);
nt_type = regset->nt_type;
if (nt_type)
{
iov.iov_base = buf;
iov.iov_len = regset->size;
data = (void *) &iov;
}
else
data = buf;
#ifndef __sparc__
res = ptrace (regset->get_request, pid,
(PTRACE_ARG3_TYPE) (long) nt_type, data);
#else
res = ptrace (regset->get_request, pid, data, nt_type);
#endif
if (res < 0)
{
if (errno == EIO)
{
/* If we get EIO on a regset, do not try it again for
this process. */
disabled_regsets[regset - target_regsets] = 1;
free (buf);
continue;
}
else
{
char s[256];
sprintf (s, "ptrace(regsets_fetch_inferior_registers) PID=%d",
pid);
perror (s);
}
}
else if (regset->type == GENERAL_REGS)
saw_general_regs = 1;
regset->store_function (regcache, buf);
regset ++;
free (buf);
}
if (saw_general_regs)
return 0;
else
return 1;
}
static int
regsets_store_inferior_registers (struct regcache *regcache)
{
struct regset_info *regset;
int saw_general_regs = 0;
int pid;
struct iovec iov;
regset = target_regsets;
pid = lwpid_of (get_thread_lwp (current_inferior));
while (regset->size >= 0)
{
void *buf, *data;
int nt_type, res;
if (regset->size == 0 || disabled_regsets[regset - target_regsets])
{
regset ++;
continue;
}
buf = xmalloc (regset->size);
/* First fill the buffer with the current register set contents,
in case there are any items in the kernel's regset that are
not in gdbserver's regcache. */
nt_type = regset->nt_type;
if (nt_type)
{
iov.iov_base = buf;
iov.iov_len = regset->size;
data = (void *) &iov;
}
else
data = buf;
#ifndef __sparc__
res = ptrace (regset->get_request, pid,
(PTRACE_ARG3_TYPE) (long) nt_type, data);
#else
res = ptrace (regset->get_request, pid, data, nt_type);
#endif
if (res == 0)
{
/* Then overlay our cached registers on that. */
regset->fill_function (regcache, buf);
/* Only now do we write the register set. */
#ifndef __sparc__
res = ptrace (regset->set_request, pid,
(PTRACE_ARG3_TYPE) (long) nt_type, data);
#else
res = ptrace (regset->set_request, pid, data, nt_type);
#endif
}
if (res < 0)
{
if (errno == EIO)
{
/* If we get EIO on a regset, do not try it again for
this process. */
disabled_regsets[regset - target_regsets] = 1;
free (buf);
continue;
}
else if (errno == ESRCH)
{
/* At this point, ESRCH should mean the process is
already gone, in which case we simply ignore attempts
to change its registers. See also the related
comment in linux_resume_one_lwp. */
free (buf);
return 0;
}
else
{
perror ("Warning: ptrace(regsets_store_inferior_registers)");
}
}
else if (regset->type == GENERAL_REGS)
saw_general_regs = 1;
regset ++;
free (buf);
}
if (saw_general_regs)
return 0;
else
return 1;
}
#else /* !HAVE_LINUX_REGSETS */
#define use_linux_regsets 0
#define regsets_fetch_inferior_registers(regcache) 1
#define regsets_store_inferior_registers(regcache) 1
#endif
/* Return 1 if register REGNO is supported by one of the regset ptrace
calls or 0 if it has to be transferred individually. */
static int
linux_register_in_regsets (int regno)
{
unsigned char mask = 1 << (regno % 8);
size_t index = regno / 8;
return (use_linux_regsets
&& (the_low_target.regset_bitmap == NULL
|| (the_low_target.regset_bitmap[index] & mask) != 0));
}
#ifdef HAVE_LINUX_USRREGS
int
register_addr (int regnum)
{
int addr;
if (regnum < 0 || regnum >= the_low_target.num_regs)
error ("Invalid register number %d.", regnum);
addr = the_low_target.regmap[regnum];
return addr;
}
/* Fetch one register. */
static void
fetch_register (struct regcache *regcache, int regno)
{
CORE_ADDR regaddr;
int i, size;
char *buf;
int pid;
if (regno >= the_low_target.num_regs)
return;
if ((*the_low_target.cannot_fetch_register) (regno))
return;
regaddr = register_addr (regno);
if (regaddr == -1)
return;
size = ((register_size (regno) + sizeof (PTRACE_XFER_TYPE) - 1)
& -sizeof (PTRACE_XFER_TYPE));
buf = alloca (size);
pid = lwpid_of (get_thread_lwp (current_inferior));
for (i = 0; i < size; i += sizeof (PTRACE_XFER_TYPE))
{
errno = 0;
*(PTRACE_XFER_TYPE *) (buf + i) =
ptrace (PTRACE_PEEKUSER, pid,
/* Coerce to a uintptr_t first to avoid potential gcc warning
of coercing an 8 byte integer to a 4 byte pointer. */
(PTRACE_ARG3_TYPE) (uintptr_t) regaddr, (PTRACE_ARG4_TYPE) 0);
regaddr += sizeof (PTRACE_XFER_TYPE);
if (errno != 0)
error ("reading register %d: %s", regno, strerror (errno));
}
if (the_low_target.supply_ptrace_register)
the_low_target.supply_ptrace_register (regcache, regno, buf);
else
supply_register (regcache, regno, buf);
}
/* Store one register. */
static void
store_register (struct regcache *regcache, int regno)
{
CORE_ADDR regaddr;
int i, size;
char *buf;
int pid;
if (regno >= the_low_target.num_regs)
return;
if ((*the_low_target.cannot_store_register) (regno))
return;
regaddr = register_addr (regno);
if (regaddr == -1)
return;
size = ((register_size (regno) + sizeof (PTRACE_XFER_TYPE) - 1)
& -sizeof (PTRACE_XFER_TYPE));
buf = alloca (size);
memset (buf, 0, size);
if (the_low_target.collect_ptrace_register)
the_low_target.collect_ptrace_register (regcache, regno, buf);
else
collect_register (regcache, regno, buf);
pid = lwpid_of (get_thread_lwp (current_inferior));
for (i = 0; i < size; i += sizeof (PTRACE_XFER_TYPE))
{
errno = 0;
ptrace (PTRACE_POKEUSER, pid,
/* Coerce to a uintptr_t first to avoid potential gcc warning
about coercing an 8 byte integer to a 4 byte pointer. */
(PTRACE_ARG3_TYPE) (uintptr_t) regaddr,
(PTRACE_ARG4_TYPE) *(PTRACE_XFER_TYPE *) (buf + i));
if (errno != 0)
{
/* At this point, ESRCH should mean the process is
already gone, in which case we simply ignore attempts
to change its registers. See also the related
comment in linux_resume_one_lwp. */
if (errno == ESRCH)
return;
if ((*the_low_target.cannot_store_register) (regno) == 0)
error ("writing register %d: %s", regno, strerror (errno));
}
regaddr += sizeof (PTRACE_XFER_TYPE);
}
}
/* Fetch all registers, or just one, from the child process.
If REGNO is -1, do this for all registers, skipping any that are
assumed to have been retrieved by regsets_fetch_inferior_registers,
unless ALL is non-zero.
Otherwise, REGNO specifies which register (so we can save time). */
static void
usr_fetch_inferior_registers (struct regcache *regcache, int regno, int all)
{
if (regno == -1)
{
for (regno = 0; regno < the_low_target.num_regs; regno++)
if (all || !linux_register_in_regsets (regno))
fetch_register (regcache, regno);
}
else
fetch_register (regcache, regno);
}
/* Store our register values back into the inferior.
If REGNO is -1, do this for all registers, skipping any that are
assumed to have been saved by regsets_store_inferior_registers,
unless ALL is non-zero.
Otherwise, REGNO specifies which register (so we can save time). */
static void
usr_store_inferior_registers (struct regcache *regcache, int regno, int all)
{
if (regno == -1)
{
for (regno = 0; regno < the_low_target.num_regs; regno++)
if (all || !linux_register_in_regsets (regno))
store_register (regcache, regno);
}
else
store_register (regcache, regno);
}
#else /* !HAVE_LINUX_USRREGS */
#define usr_fetch_inferior_registers(regcache, regno, all) do {} while (0)
#define usr_store_inferior_registers(regcache, regno, all) do {} while (0)
#endif
void
linux_fetch_registers (struct regcache *regcache, int regno)
{
int use_regsets;
int all = 0;
if (regno == -1)
{
if (the_low_target.fetch_register != NULL)
for (regno = 0; regno < the_low_target.num_regs; regno++)
(*the_low_target.fetch_register) (regcache, regno);
all = regsets_fetch_inferior_registers (regcache);
usr_fetch_inferior_registers (regcache, -1, all);
}
else
{
if (the_low_target.fetch_register != NULL
&& (*the_low_target.fetch_register) (regcache, regno))
return;
use_regsets = linux_register_in_regsets (regno);
if (use_regsets)
all = regsets_fetch_inferior_registers (regcache);
if (!use_regsets || all)
usr_fetch_inferior_registers (regcache, regno, 1);
}
}
void
linux_store_registers (struct regcache *regcache, int regno)
{
int use_regsets;
int all = 0;
if (regno == -1)
{
all = regsets_store_inferior_registers (regcache);
usr_store_inferior_registers (regcache, regno, all);
}
else
{
use_regsets = linux_register_in_regsets (regno);
if (use_regsets)
all = regsets_store_inferior_registers (regcache);
if (!use_regsets || all)
usr_store_inferior_registers (regcache, regno, 1);
}
}
/* Copy LEN bytes from inferior's memory starting at MEMADDR
to debugger memory starting at MYADDR. */
static int
linux_read_memory (CORE_ADDR memaddr, unsigned char *myaddr, int len)
{
int pid = lwpid_of (get_thread_lwp (current_inferior));
register PTRACE_XFER_TYPE *buffer;
register CORE_ADDR addr;
register int count;
char filename[64];
register int i;
int ret;
int fd;
/* Try using /proc. Don't bother for one word. */
if (len >= 3 * sizeof (long))
{
int bytes;
/* We could keep this file open and cache it - possibly one per
thread. That requires some juggling, but is even faster. */
sprintf (filename, "/proc/%d/mem", pid);
fd = open (filename, O_RDONLY | O_LARGEFILE);
if (fd == -1)
goto no_proc;
/* If pread64 is available, use it. It's faster if the kernel
supports it (only one syscall), and it's 64-bit safe even on
32-bit platforms (for instance, SPARC debugging a SPARC64
application). */
#ifdef HAVE_PREAD64
bytes = pread64 (fd, myaddr, len, memaddr);
#else
bytes = -1;
if (lseek (fd, memaddr, SEEK_SET) != -1)
bytes = read (fd, myaddr, len);
#endif
close (fd);
if (bytes == len)
return 0;
/* Some data was read, we'll try to get the rest with ptrace. */
if (bytes > 0)
{
memaddr += bytes;
myaddr += bytes;
len -= bytes;
}
}
no_proc:
/* Round starting address down to longword boundary. */
addr = memaddr & -(CORE_ADDR) sizeof (PTRACE_XFER_TYPE);
/* Round ending address up; get number of longwords that makes. */
count = ((((memaddr + len) - addr) + sizeof (PTRACE_XFER_TYPE) - 1)
/ sizeof (PTRACE_XFER_TYPE));
/* Allocate buffer of that many longwords. */
buffer = (PTRACE_XFER_TYPE *) alloca (count * sizeof (PTRACE_XFER_TYPE));
/* Read all the longwords */
errno = 0;
for (i = 0; i < count; i++, addr += sizeof (PTRACE_XFER_TYPE))
{
/* Coerce the 3rd arg to a uintptr_t first to avoid potential gcc warning
about coercing an 8 byte integer to a 4 byte pointer. */
buffer[i] = ptrace (PTRACE_PEEKTEXT, pid,
(PTRACE_ARG3_TYPE) (uintptr_t) addr,
(PTRACE_ARG4_TYPE) 0);
if (errno)
break;
}
ret = errno;
/* Copy appropriate bytes out of the buffer. */
if (i > 0)
{
i *= sizeof (PTRACE_XFER_TYPE);
i -= memaddr & (sizeof (PTRACE_XFER_TYPE) - 1);
memcpy (myaddr,
(char *) buffer + (memaddr & (sizeof (PTRACE_XFER_TYPE) - 1)),
i < len ? i : len);
}
return ret;
}
/* Copy LEN bytes of data from debugger memory at MYADDR to inferior's
memory at MEMADDR. On failure (cannot write to the inferior)
returns the value of errno. Always succeeds if LEN is zero. */
static int
linux_write_memory (CORE_ADDR memaddr, const unsigned char *myaddr, int len)
{
register int i;
/* Round starting address down to longword boundary. */
register CORE_ADDR addr = memaddr & -(CORE_ADDR) sizeof (PTRACE_XFER_TYPE);
/* Round ending address up; get number of longwords that makes. */
register int count
= (((memaddr + len) - addr) + sizeof (PTRACE_XFER_TYPE) - 1)
/ sizeof (PTRACE_XFER_TYPE);
/* Allocate buffer of that many longwords. */
register PTRACE_XFER_TYPE *buffer = (PTRACE_XFER_TYPE *)
alloca (count * sizeof (PTRACE_XFER_TYPE));
int pid = lwpid_of (get_thread_lwp (current_inferior));
if (len == 0)
{
/* Zero length write always succeeds. */
return 0;
}
if (debug_threads)
{
/* Dump up to four bytes. */
unsigned int val = * (unsigned int *) myaddr;
if (len == 1)
val = val & 0xff;
else if (len == 2)
val = val & 0xffff;
else if (len == 3)
val = val & 0xffffff;
fprintf (stderr, "Writing %0*x to 0x%08lx\n", 2 * ((len < 4) ? len : 4),
val, (long)memaddr);
}
/* Fill start and end extra bytes of buffer with existing memory data. */
errno = 0;
/* Coerce the 3rd arg to a uintptr_t first to avoid potential gcc warning
about coercing an 8 byte integer to a 4 byte pointer. */
buffer[0] = ptrace (PTRACE_PEEKTEXT, pid,
(PTRACE_ARG3_TYPE) (uintptr_t) addr,
(PTRACE_ARG4_TYPE) 0);
if (errno)
return errno;
if (count > 1)
{
errno = 0;
buffer[count - 1]
= ptrace (PTRACE_PEEKTEXT, pid,
/* Coerce to a uintptr_t first to avoid potential gcc warning
about coercing an 8 byte integer to a 4 byte pointer. */
(PTRACE_ARG3_TYPE) (uintptr_t) (addr + (count - 1)
* sizeof (PTRACE_XFER_TYPE)),
(PTRACE_ARG4_TYPE) 0);
if (errno)
return errno;
}
/* Copy data to be written over corresponding part of buffer. */
memcpy ((char *) buffer + (memaddr & (sizeof (PTRACE_XFER_TYPE) - 1)),
myaddr, len);
/* Write the entire buffer. */
for (i = 0; i < count; i++, addr += sizeof (PTRACE_XFER_TYPE))
{
errno = 0;
ptrace (PTRACE_POKETEXT, pid,
/* Coerce to a uintptr_t first to avoid potential gcc warning
about coercing an 8 byte integer to a 4 byte pointer. */
(PTRACE_ARG3_TYPE) (uintptr_t) addr,
(PTRACE_ARG4_TYPE) buffer[i]);
if (errno)
return errno;
}
return 0;
}
/* Non-zero if the kernel supports PTRACE_O_TRACEFORK. */
static int linux_supports_tracefork_flag;
static void
linux_enable_event_reporting (int pid)
{
if (!linux_supports_tracefork_flag)
return;
ptrace (PTRACE_SETOPTIONS, pid, (PTRACE_ARG3_TYPE) 0,
(PTRACE_ARG4_TYPE) PTRACE_O_TRACECLONE);
}
/* Helper functions for linux_test_for_tracefork, called via clone (). */
static int
linux_tracefork_grandchild (void *arg)
{
_exit (0);
}
#define STACK_SIZE 4096
static int
linux_tracefork_child (void *arg)
{
ptrace (PTRACE_TRACEME, 0, (PTRACE_ARG3_TYPE) 0, (PTRACE_ARG4_TYPE) 0);
kill (getpid (), SIGSTOP);
#if !(defined(__UCLIBC__) && defined(HAS_NOMMU))
if (fork () == 0)
linux_tracefork_grandchild (NULL);
#else /* defined(__UCLIBC__) && defined(HAS_NOMMU) */
#ifdef __ia64__
__clone2 (linux_tracefork_grandchild, arg, STACK_SIZE,
CLONE_VM | SIGCHLD, NULL);
#else
clone (linux_tracefork_grandchild, (char *) arg + STACK_SIZE,
CLONE_VM | SIGCHLD, NULL);
#endif
#endif /* defined(__UCLIBC__) && defined(HAS_NOMMU) */
_exit (0);
}
/* Determine if PTRACE_O_TRACEFORK can be used to follow fork events. Make
sure that we can enable the option, and that it had the desired
effect. */
static void
linux_test_for_tracefork (void)
{
int child_pid, ret, status;
long second_pid;
#if defined(__UCLIBC__) && defined(HAS_NOMMU)
char *stack = xmalloc (STACK_SIZE * 4);
#endif /* defined(__UCLIBC__) && defined(HAS_NOMMU) */
linux_supports_tracefork_flag = 0;
#if !(defined(__UCLIBC__) && defined(HAS_NOMMU))
child_pid = fork ();
if (child_pid == 0)
linux_tracefork_child (NULL);
#else /* defined(__UCLIBC__) && defined(HAS_NOMMU) */
/* Use CLONE_VM instead of fork, to support uClinux (no MMU). */
#ifdef __ia64__
child_pid = __clone2 (linux_tracefork_child, stack, STACK_SIZE,
CLONE_VM | SIGCHLD, stack + STACK_SIZE * 2);
#else /* !__ia64__ */
child_pid = clone (linux_tracefork_child, stack + STACK_SIZE,
CLONE_VM | SIGCHLD, stack + STACK_SIZE * 2);
#endif /* !__ia64__ */
#endif /* defined(__UCLIBC__) && defined(HAS_NOMMU) */
if (child_pid == -1)
perror_with_name ("clone");
ret = my_waitpid (child_pid, &status, 0);
if (ret == -1)
perror_with_name ("waitpid");
else if (ret != child_pid)
error ("linux_test_for_tracefork: waitpid: unexpected result %d.", ret);
if (! WIFSTOPPED (status))
error ("linux_test_for_tracefork: waitpid: unexpected status %d.", status);
ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_ARG3_TYPE) 0,
(PTRACE_ARG4_TYPE) PTRACE_O_TRACEFORK);
if (ret != 0)
{
ret = ptrace (PTRACE_KILL, child_pid, (PTRACE_ARG3_TYPE) 0,
(PTRACE_ARG4_TYPE) 0);
if (ret != 0)
{
warning ("linux_test_for_tracefork: failed to kill child");
return;
}
ret = my_waitpid (child_pid, &status, 0);
if (ret != child_pid)
warning ("linux_test_for_tracefork: failed to wait for killed child");
else if (!WIFSIGNALED (status))
warning ("linux_test_for_tracefork: unexpected wait status 0x%x from "
"killed child", status);
return;
}
ret = ptrace (PTRACE_CONT, child_pid, (PTRACE_ARG3_TYPE) 0,
(PTRACE_ARG4_TYPE) 0);
if (ret != 0)
warning ("linux_test_for_tracefork: failed to resume child");
ret = my_waitpid (child_pid, &status, 0);
if (ret == child_pid && WIFSTOPPED (status)
&& status >> 16 == PTRACE_EVENT_FORK)
{
second_pid = 0;
ret = ptrace (PTRACE_GETEVENTMSG, child_pid, (PTRACE_ARG3_TYPE) 0,
&second_pid);
if (ret == 0 && second_pid != 0)
{
int second_status;
linux_supports_tracefork_flag = 1;
my_waitpid (second_pid, &second_status, 0);
ret = ptrace (PTRACE_KILL, second_pid, (PTRACE_ARG3_TYPE) 0,
(PTRACE_ARG4_TYPE) 0);
if (ret != 0)
warning ("linux_test_for_tracefork: failed to kill second child");
my_waitpid (second_pid, &status, 0);
}
}
else
warning ("linux_test_for_tracefork: unexpected result from waitpid "
"(%d, status 0x%x)", ret, status);
do
{
ret = ptrace (PTRACE_KILL, child_pid, (PTRACE_ARG3_TYPE) 0,
(PTRACE_ARG4_TYPE) 0);
if (ret != 0)
warning ("linux_test_for_tracefork: failed to kill child");
my_waitpid (child_pid, &status, 0);
}
while (WIFSTOPPED (status));
#if defined(__UCLIBC__) && defined(HAS_NOMMU)
free (stack);
#endif /* defined(__UCLIBC__) && defined(HAS_NOMMU) */
}
static void
linux_look_up_symbols (void)
{
#ifdef USE_THREAD_DB
struct process_info *proc = current_process ();
if (proc->private->thread_db != NULL)
return;
/* If the kernel supports tracing forks then it also supports tracing
clones, and then we don't need to use the magic thread event breakpoint
to learn about threads. */
thread_db_init (!linux_supports_tracefork_flag);
#endif
}
static void
linux_request_interrupt (void)
{
extern unsigned long signal_pid;
if (!ptid_equal (cont_thread, null_ptid)
&& !ptid_equal (cont_thread, minus_one_ptid))
{
struct lwp_info *lwp;
int lwpid;
lwp = get_thread_lwp (current_inferior);
lwpid = lwpid_of (lwp);
kill_lwp (lwpid, SIGINT);
}
else
kill_lwp (signal_pid, SIGINT);
}
/* Copy LEN bytes from inferior's auxiliary vector starting at OFFSET
to debugger memory starting at MYADDR. */
static int
linux_read_auxv (CORE_ADDR offset, unsigned char *myaddr, unsigned int len)
{
char filename[PATH_MAX];
int fd, n;
int pid = lwpid_of (get_thread_lwp (current_inferior));
xsnprintf (filename, sizeof filename, "/proc/%d/auxv", pid);
fd = open (filename, O_RDONLY);
if (fd < 0)
return -1;
if (offset != (CORE_ADDR) 0
&& lseek (fd, (off_t) offset, SEEK_SET) != (off_t) offset)
n = -1;
else
n = read (fd, myaddr, len);
close (fd);
return n;
}
/* These breakpoint and watchpoint related wrapper functions simply
pass on the function call if the target has registered a
corresponding function. */
static int
linux_insert_point (char type, CORE_ADDR addr, int len)
{
if (the_low_target.insert_point != NULL)
return the_low_target.insert_point (type, addr, len);
else
/* Unsupported (see target.h). */
return 1;
}
static int
linux_remove_point (char type, CORE_ADDR addr, int len)
{
if (the_low_target.remove_point != NULL)
return the_low_target.remove_point (type, addr, len);
else
/* Unsupported (see target.h). */
return 1;
}
static int
linux_stopped_by_watchpoint (void)
{
struct lwp_info *lwp = get_thread_lwp (current_inferior);
return lwp->stopped_by_watchpoint;
}
static CORE_ADDR
linux_stopped_data_address (void)
{
struct lwp_info *lwp = get_thread_lwp (current_inferior);
return lwp->stopped_data_address;
}
#if defined(__UCLIBC__) && defined(HAS_NOMMU)
#if ! (defined(PT_TEXT_ADDR) \
|| defined(PT_DATA_ADDR) \
|| defined(PT_TEXT_END_ADDR))
#if defined(__mcoldfire__)
/* These should really be defined in the kernel's ptrace.h header. */
#define PT_TEXT_ADDR 49*4
#define PT_DATA_ADDR 50*4
#define PT_TEXT_END_ADDR 51*4
#elif defined(BFIN)
#define PT_TEXT_ADDR 220
#define PT_TEXT_END_ADDR 224
#define PT_DATA_ADDR 228
#elif defined(__TMS320C6X__)
#define PT_TEXT_ADDR (0x10000*4)
#define PT_DATA_ADDR (0x10004*4)
#define PT_TEXT_END_ADDR (0x10008*4)
#endif
#endif
/* Under uClinux, programs are loaded at non-zero offsets, which we need
to tell gdb about. */
static int
linux_read_offsets (CORE_ADDR *text_p, CORE_ADDR *data_p)
{
#if defined(PT_TEXT_ADDR) && defined(PT_DATA_ADDR) && defined(PT_TEXT_END_ADDR)
unsigned long text, text_end, data;
int pid = lwpid_of (get_thread_lwp (current_inferior));
errno = 0;
text = ptrace (PTRACE_PEEKUSER, pid, (PTRACE_ARG3_TYPE) PT_TEXT_ADDR,
(PTRACE_ARG4_TYPE) 0);
text_end = ptrace (PTRACE_PEEKUSER, pid, (PTRACE_ARG3_TYPE) PT_TEXT_END_ADDR,
(PTRACE_ARG4_TYPE) 0);
data = ptrace (PTRACE_PEEKUSER, pid, (PTRACE_ARG3_TYPE) PT_DATA_ADDR,
(PTRACE_ARG4_TYPE) 0);
if (errno == 0)
{
/* Both text and data offsets produced at compile-time (and so
used by gdb) are relative to the beginning of the program,
with the data segment immediately following the text segment.
However, the actual runtime layout in memory may put the data
somewhere else, so when we send gdb a data base-address, we
use the real data base address and subtract the compile-time
data base-address from it (which is just the length of the
text segment). BSS immediately follows data in both
cases. */
*text_p = text;
*data_p = data - (text_end - text);
return 1;
}
#endif
return 0;
}
#endif
static int
linux_qxfer_osdata (const char *annex,
unsigned char *readbuf, unsigned const char *writebuf,
CORE_ADDR offset, int len)
{
return linux_common_xfer_osdata (annex, readbuf, offset, len);
}
/* Convert a native/host siginfo object, into/from the siginfo in the
layout of the inferiors' architecture. */
static void
siginfo_fixup (siginfo_t *siginfo, void *inf_siginfo, int direction)
{
int done = 0;
if (the_low_target.siginfo_fixup != NULL)
done = the_low_target.siginfo_fixup (siginfo, inf_siginfo, direction);
/* If there was no callback, or the callback didn't do anything,
then just do a straight memcpy. */
if (!done)
{
if (direction == 1)
memcpy (siginfo, inf_siginfo, sizeof (siginfo_t));
else
memcpy (inf_siginfo, siginfo, sizeof (siginfo_t));
}
}
static int
linux_xfer_siginfo (const char *annex, unsigned char *readbuf,
unsigned const char *writebuf, CORE_ADDR offset, int len)
{
int pid;
siginfo_t siginfo;
char inf_siginfo[sizeof (siginfo_t)];
if (current_inferior == NULL)
return -1;
pid = lwpid_of (get_thread_lwp (current_inferior));
if (debug_threads)
fprintf (stderr, "%s siginfo for lwp %d.\n",
readbuf != NULL ? "Reading" : "Writing",
pid);
if (offset >= sizeof (siginfo))
return -1;
if (ptrace (PTRACE_GETSIGINFO, pid, (PTRACE_ARG3_TYPE) 0, &siginfo) != 0)
return -1;
/* When GDBSERVER is built as a 64-bit application, ptrace writes into
SIGINFO an object with 64-bit layout. Since debugging a 32-bit
inferior with a 64-bit GDBSERVER should look the same as debugging it
with a 32-bit GDBSERVER, we need to convert it. */
siginfo_fixup (&siginfo, inf_siginfo, 0);
if (offset + len > sizeof (siginfo))
len = sizeof (siginfo) - offset;
if (readbuf != NULL)
memcpy (readbuf, inf_siginfo + offset, len);
else
{
memcpy (inf_siginfo + offset, writebuf, len);
/* Convert back to ptrace layout before flushing it out. */
siginfo_fixup (&siginfo, inf_siginfo, 1);
if (ptrace (PTRACE_SETSIGINFO, pid, (PTRACE_ARG3_TYPE) 0, &siginfo) != 0)
return -1;
}
return len;
}
/* SIGCHLD handler that serves two purposes: In non-stop/async mode,
so we notice when children change state; as the handler for the
sigsuspend in my_waitpid. */
static void
sigchld_handler (int signo)
{
int old_errno = errno;
if (debug_threads)
{
do
{
/* fprintf is not async-signal-safe, so call write
directly. */
if (write (2, "sigchld_handler\n",
sizeof ("sigchld_handler\n") - 1) < 0)
break; /* just ignore */
} while (0);
}
if (target_is_async_p ())
async_file_mark (); /* trigger a linux_wait */
errno = old_errno;
}
static int
linux_supports_non_stop (void)
{
return 1;
}
static int
linux_async (int enable)
{
int previous = (linux_event_pipe[0] != -1);
if (debug_threads)
fprintf (stderr, "linux_async (%d), previous=%d\n",
enable, previous);
if (previous != enable)
{
sigset_t mask;
sigemptyset (&mask);
sigaddset (&mask, SIGCHLD);
sigprocmask (SIG_BLOCK, &mask, NULL);
if (enable)
{
if (pipe (linux_event_pipe) == -1)
fatal ("creating event pipe failed.");
fcntl (linux_event_pipe[0], F_SETFL, O_NONBLOCK);
fcntl (linux_event_pipe[1], F_SETFL, O_NONBLOCK);
/* Register the event loop handler. */
add_file_handler (linux_event_pipe[0],
handle_target_event, NULL);
/* Always trigger a linux_wait. */
async_file_mark ();
}
else
{
delete_file_handler (linux_event_pipe[0]);
close (linux_event_pipe[0]);
close (linux_event_pipe[1]);
linux_event_pipe[0] = -1;
linux_event_pipe[1] = -1;
}
sigprocmask (SIG_UNBLOCK, &mask, NULL);
}
return previous;
}
static int
linux_start_non_stop (int nonstop)
{
/* Register or unregister from event-loop accordingly. */
linux_async (nonstop);
return 0;
}
static int
linux_supports_multi_process (void)
{
return 1;
}
static int
linux_supports_disable_randomization (void)
{
#ifdef HAVE_PERSONALITY
return 1;
#else
return 0;
#endif
}
static int
linux_supports_agent (void)
{
return 1;
}
/* Enumerate spufs IDs for process PID. */
static int
spu_enumerate_spu_ids (long pid, unsigned char *buf, CORE_ADDR offset, int len)
{
int pos = 0;
int written = 0;
char path[128];
DIR *dir;
struct dirent *entry;
sprintf (path, "/proc/%ld/fd", pid);
dir = opendir (path);
if (!dir)
return -1;
rewinddir (dir);
while ((entry = readdir (dir)) != NULL)
{
struct stat st;
struct statfs stfs;
int fd;
fd = atoi (entry->d_name);
if (!fd)
continue;
sprintf (path, "/proc/%ld/fd/%d", pid, fd);
if (stat (path, &st) != 0)
continue;
if (!S_ISDIR (st.st_mode))
continue;
if (statfs (path, &stfs) != 0)
continue;
if (stfs.f_type != SPUFS_MAGIC)
continue;
if (pos >= offset && pos + 4 <= offset + len)
{
*(unsigned int *)(buf + pos - offset) = fd;
written += 4;
}
pos += 4;
}
closedir (dir);
return written;
}
/* Implements the to_xfer_partial interface for the TARGET_OBJECT_SPU
object type, using the /proc file system. */
static int
linux_qxfer_spu (const char *annex, unsigned char *readbuf,
unsigned const char *writebuf,
CORE_ADDR offset, int len)
{
long pid = lwpid_of (get_thread_lwp (current_inferior));
char buf[128];
int fd = 0;
int ret = 0;
if (!writebuf && !readbuf)
return -1;
if (!*annex)
{
if (!readbuf)
return -1;
else
return spu_enumerate_spu_ids (pid, readbuf, offset, len);
}
sprintf (buf, "/proc/%ld/fd/%s", pid, annex);
fd = open (buf, writebuf? O_WRONLY : O_RDONLY);
if (fd <= 0)
return -1;
if (offset != 0
&& lseek (fd, (off_t) offset, SEEK_SET) != (off_t) offset)
{
close (fd);
return 0;
}
if (writebuf)
ret = write (fd, writebuf, (size_t) len);
else
ret = read (fd, readbuf, (size_t) len);
close (fd);
return ret;
}
#if defined PT_GETDSBT || defined PTRACE_GETFDPIC
struct target_loadseg
{
/* Core address to which the segment is mapped. */
Elf32_Addr addr;
/* VMA recorded in the program header. */
Elf32_Addr p_vaddr;
/* Size of this segment in memory. */
Elf32_Word p_memsz;
};
# if defined PT_GETDSBT
struct target_loadmap
{
/* Protocol version number, must be zero. */
Elf32_Word version;
/* Pointer to the DSBT table, its size, and the DSBT index. */
unsigned *dsbt_table;
unsigned dsbt_size, dsbt_index;
/* Number of segments in this map. */
Elf32_Word nsegs;
/* The actual memory map. */
struct target_loadseg segs[/*nsegs*/];
};
# define LINUX_LOADMAP PT_GETDSBT
# define LINUX_LOADMAP_EXEC PTRACE_GETDSBT_EXEC
# define LINUX_LOADMAP_INTERP PTRACE_GETDSBT_INTERP
# else
struct target_loadmap
{
/* Protocol version number, must be zero. */
Elf32_Half version;
/* Number of segments in this map. */
Elf32_Half nsegs;
/* The actual memory map. */
struct target_loadseg segs[/*nsegs*/];
};
# define LINUX_LOADMAP PTRACE_GETFDPIC
# define LINUX_LOADMAP_EXEC PTRACE_GETFDPIC_EXEC
# define LINUX_LOADMAP_INTERP PTRACE_GETFDPIC_INTERP
# endif
static int
linux_read_loadmap (const char *annex, CORE_ADDR offset,
unsigned char *myaddr, unsigned int len)
{
int pid = lwpid_of (get_thread_lwp (current_inferior));
int addr = -1;
struct target_loadmap *data = NULL;
unsigned int actual_length, copy_length;
if (strcmp (annex, "exec") == 0)
addr = (int) LINUX_LOADMAP_EXEC;
else if (strcmp (annex, "interp") == 0)
addr = (int) LINUX_LOADMAP_INTERP;
else
return -1;
if (ptrace (LINUX_LOADMAP, pid, addr, &data) != 0)
return -1;
if (data == NULL)
return -1;
actual_length = sizeof (struct target_loadmap)
+ sizeof (struct target_loadseg) * data->nsegs;
if (offset < 0 || offset > actual_length)
return -1;
copy_length = actual_length - offset < len ? actual_length - offset : len;
memcpy (myaddr, (char *) data + offset, copy_length);
return copy_length;
}
#else
# define linux_read_loadmap NULL
#endif /* defined PT_GETDSBT || defined PTRACE_GETFDPIC */
static void
linux_process_qsupported (const char *query)
{
if (the_low_target.process_qsupported != NULL)
the_low_target.process_qsupported (query);
}
static int
linux_supports_tracepoints (void)
{
if (*the_low_target.supports_tracepoints == NULL)
return 0;
return (*the_low_target.supports_tracepoints) ();
}
static CORE_ADDR
linux_read_pc (struct regcache *regcache)
{
if (the_low_target.get_pc == NULL)
return 0;
return (*the_low_target.get_pc) (regcache);
}
static void
linux_write_pc (struct regcache *regcache, CORE_ADDR pc)
{
gdb_assert (the_low_target.set_pc != NULL);
(*the_low_target.set_pc) (regcache, pc);
}
static int
linux_thread_stopped (struct thread_info *thread)
{
return get_thread_lwp (thread)->stopped;
}
/* This exposes stop-all-threads functionality to other modules. */
static void
linux_pause_all (int freeze)
{
stop_all_lwps (freeze, NULL);
}
/* This exposes unstop-all-threads functionality to other gdbserver
modules. */
static void
linux_unpause_all (int unfreeze)
{
unstop_all_lwps (unfreeze, NULL);
}
static int
linux_prepare_to_access_memory (void)
{
/* Neither ptrace nor /proc/PID/mem allow accessing memory through a
running LWP. */
if (non_stop)
linux_pause_all (1);
return 0;
}
static void
linux_done_accessing_memory (void)
{
/* Neither ptrace nor /proc/PID/mem allow accessing memory through a
running LWP. */
if (non_stop)
linux_unpause_all (1);
}
static int
linux_install_fast_tracepoint_jump_pad (CORE_ADDR tpoint, CORE_ADDR tpaddr,
CORE_ADDR collector,
CORE_ADDR lockaddr,
ULONGEST orig_size,
CORE_ADDR *jump_entry,
CORE_ADDR *trampoline,
ULONGEST *trampoline_size,
unsigned char *jjump_pad_insn,
ULONGEST *jjump_pad_insn_size,
CORE_ADDR *adjusted_insn_addr,
CORE_ADDR *adjusted_insn_addr_end,
char *err)
{
return (*the_low_target.install_fast_tracepoint_jump_pad)
(tpoint, tpaddr, collector, lockaddr, orig_size,
jump_entry, trampoline, trampoline_size,
jjump_pad_insn, jjump_pad_insn_size,
adjusted_insn_addr, adjusted_insn_addr_end,
err);
}
static struct emit_ops *
linux_emit_ops (void)
{
if (the_low_target.emit_ops != NULL)
return (*the_low_target.emit_ops) ();
else
return NULL;
}
static int
linux_get_min_fast_tracepoint_insn_len (void)
{
return (*the_low_target.get_min_fast_tracepoint_insn_len) ();
}
/* Extract &phdr and num_phdr in the inferior. Return 0 on success. */
static int
get_phdr_phnum_from_proc_auxv (const int pid, const int is_elf64,
CORE_ADDR *phdr_memaddr, int *num_phdr)
{
char filename[PATH_MAX];
int fd;
const int auxv_size = is_elf64
? sizeof (Elf64_auxv_t) : sizeof (Elf32_auxv_t);
char buf[sizeof (Elf64_auxv_t)]; /* The larger of the two. */
xsnprintf (filename, sizeof filename, "/proc/%d/auxv", pid);
fd = open (filename, O_RDONLY);
if (fd < 0)
return 1;
*phdr_memaddr = 0;
*num_phdr = 0;
while (read (fd, buf, auxv_size) == auxv_size
&& (*phdr_memaddr == 0 || *num_phdr == 0))
{
if (is_elf64)
{
Elf64_auxv_t *const aux = (Elf64_auxv_t *) buf;
switch (aux->a_type)
{
case AT_PHDR:
*phdr_memaddr = aux->a_un.a_val;
break;
case AT_PHNUM:
*num_phdr = aux->a_un.a_val;
break;
}
}
else
{
Elf32_auxv_t *const aux = (Elf32_auxv_t *) buf;
switch (aux->a_type)
{
case AT_PHDR:
*phdr_memaddr = aux->a_un.a_val;
break;
case AT_PHNUM:
*num_phdr = aux->a_un.a_val;
break;
}
}
}
close (fd);
if (*phdr_memaddr == 0 || *num_phdr == 0)
{
warning ("Unexpected missing AT_PHDR and/or AT_PHNUM: "
"phdr_memaddr = %ld, phdr_num = %d",
(long) *phdr_memaddr, *num_phdr);
return 2;
}
return 0;
}
/* Return &_DYNAMIC (via PT_DYNAMIC) in the inferior, or 0 if not present. */
static CORE_ADDR
get_dynamic (const int pid, const int is_elf64)
{
CORE_ADDR phdr_memaddr, relocation;
int num_phdr, i;
unsigned char *phdr_buf;
const int phdr_size = is_elf64 ? sizeof (Elf64_Phdr) : sizeof (Elf32_Phdr);
if (get_phdr_phnum_from_proc_auxv (pid, is_elf64, &phdr_memaddr, &num_phdr))
return 0;
gdb_assert (num_phdr < 100); /* Basic sanity check. */
phdr_buf = alloca (num_phdr * phdr_size);
if (linux_read_memory (phdr_memaddr, phdr_buf, num_phdr * phdr_size))
return 0;
/* Compute relocation: it is expected to be 0 for "regular" executables,
non-zero for PIE ones. */
relocation = -1;
for (i = 0; relocation == -1 && i < num_phdr; i++)
if (is_elf64)
{
Elf64_Phdr *const p = (Elf64_Phdr *) (phdr_buf + i * phdr_size);
if (p->p_type == PT_PHDR)
relocation = phdr_memaddr - p->p_vaddr;
}
else
{
Elf32_Phdr *const p = (Elf32_Phdr *) (phdr_buf + i * phdr_size);
if (p->p_type == PT_PHDR)
relocation = phdr_memaddr - p->p_vaddr;
}
if (relocation == -1)
{
/* PT_PHDR is optional, but necessary for PIE in general. Fortunately
any real world executables, including PIE executables, have always
PT_PHDR present. PT_PHDR is not present in some shared libraries or
in fpc (Free Pascal 2.4) binaries but neither of those have a need for
or present DT_DEBUG anyway (fpc binaries are statically linked).
Therefore if there exists DT_DEBUG there is always also PT_PHDR.
GDB could find RELOCATION also from AT_ENTRY - e_entry. */
return 0;
}
for (i = 0; i < num_phdr; i++)
{
if (is_elf64)
{
Elf64_Phdr *const p = (Elf64_Phdr *) (phdr_buf + i * phdr_size);
if (p->p_type == PT_DYNAMIC)
return p->p_vaddr + relocation;
}
else
{
Elf32_Phdr *const p = (Elf32_Phdr *) (phdr_buf + i * phdr_size);
if (p->p_type == PT_DYNAMIC)
return p->p_vaddr + relocation;
}
}
return 0;
}
/* Return &_r_debug in the inferior, or -1 if not present. Return value
can be 0 if the inferior does not yet have the library list initialized.
We look for DT_MIPS_RLD_MAP first. MIPS executables use this instead of
DT_DEBUG, although they sometimes contain an unused DT_DEBUG entry too. */
static CORE_ADDR
get_r_debug (const int pid, const int is_elf64)
{
CORE_ADDR dynamic_memaddr;
const int dyn_size = is_elf64 ? sizeof (Elf64_Dyn) : sizeof (Elf32_Dyn);
unsigned char buf[sizeof (Elf64_Dyn)]; /* The larger of the two. */
CORE_ADDR map = -1;
dynamic_memaddr = get_dynamic (pid, is_elf64);
if (dynamic_memaddr == 0)
return map;
while (linux_read_memory (dynamic_memaddr, buf, dyn_size) == 0)
{
if (is_elf64)
{
Elf64_Dyn *const dyn = (Elf64_Dyn *) buf;
#ifdef DT_MIPS_RLD_MAP
union
{
Elf64_Xword map;
unsigned char buf[sizeof (Elf64_Xword)];
}
rld_map;
if (dyn->d_tag == DT_MIPS_RLD_MAP)
{
if (linux_read_memory (dyn->d_un.d_val,
rld_map.buf, sizeof (rld_map.buf)) == 0)
return rld_map.map;
else
break;
}
#endif /* DT_MIPS_RLD_MAP */
if (dyn->d_tag == DT_DEBUG && map == -1)
map = dyn->d_un.d_val;
if (dyn->d_tag == DT_NULL)
break;
}
else
{
Elf32_Dyn *const dyn = (Elf32_Dyn *) buf;
#ifdef DT_MIPS_RLD_MAP
union
{
Elf32_Word map;
unsigned char buf[sizeof (Elf32_Word)];
}
rld_map;
if (dyn->d_tag == DT_MIPS_RLD_MAP)
{
if (linux_read_memory (dyn->d_un.d_val,
rld_map.buf, sizeof (rld_map.buf)) == 0)
return rld_map.map;
else
break;
}
#endif /* DT_MIPS_RLD_MAP */
if (dyn->d_tag == DT_DEBUG && map == -1)
map = dyn->d_un.d_val;
if (dyn->d_tag == DT_NULL)
break;
}
dynamic_memaddr += dyn_size;
}
return map;
}
/* Read one pointer from MEMADDR in the inferior. */
static int
read_one_ptr (CORE_ADDR memaddr, CORE_ADDR *ptr, int ptr_size)
{
int ret;
/* Go through a union so this works on either big or little endian
hosts, when the inferior's pointer size is smaller than the size
of CORE_ADDR. It is assumed the inferior's endianness is the
same of the superior's. */
union
{
CORE_ADDR core_addr;
unsigned int ui;
unsigned char uc;
} addr;
ret = linux_read_memory (memaddr, &addr.uc, ptr_size);
if (ret == 0)
{
if (ptr_size == sizeof (CORE_ADDR))
*ptr = addr.core_addr;
else if (ptr_size == sizeof (unsigned int))
*ptr = addr.ui;
else
gdb_assert_not_reached ("unhandled pointer size");
}
return ret;
}
struct link_map_offsets
{
/* Offset and size of r_debug.r_version. */
int r_version_offset;
/* Offset and size of r_debug.r_map. */
int r_map_offset;
/* Offset to l_addr field in struct link_map. */
int l_addr_offset;
/* Offset to l_name field in struct link_map. */
int l_name_offset;
/* Offset to l_ld field in struct link_map. */
int l_ld_offset;
/* Offset to l_next field in struct link_map. */
int l_next_offset;
/* Offset to l_prev field in struct link_map. */
int l_prev_offset;
};
/* Construct qXfer:libraries-svr4:read reply. */
static int
linux_qxfer_libraries_svr4 (const char *annex, unsigned char *readbuf,
unsigned const char *writebuf,
CORE_ADDR offset, int len)
{
char *document;
unsigned document_len;
struct process_info_private *const priv = current_process ()->private;
char filename[PATH_MAX];
int pid, is_elf64;
static const struct link_map_offsets lmo_32bit_offsets =
{
0, /* r_version offset. */
4, /* r_debug.r_map offset. */
0, /* l_addr offset in link_map. */
4, /* l_name offset in link_map. */
8, /* l_ld offset in link_map. */
12, /* l_next offset in link_map. */
16 /* l_prev offset in link_map. */
};
static const struct link_map_offsets lmo_64bit_offsets =
{
0, /* r_version offset. */
8, /* r_debug.r_map offset. */
0, /* l_addr offset in link_map. */
8, /* l_name offset in link_map. */
16, /* l_ld offset in link_map. */
24, /* l_next offset in link_map. */
32 /* l_prev offset in link_map. */
};
const struct link_map_offsets *lmo;
unsigned int machine;
if (writebuf != NULL)
return -2;
if (readbuf == NULL)
return -1;
pid = lwpid_of (get_thread_lwp (current_inferior));
xsnprintf (filename, sizeof filename, "/proc/%d/exe", pid);
is_elf64 = elf_64_file_p (filename, &machine);
lmo = is_elf64 ? &lmo_64bit_offsets : &lmo_32bit_offsets;
if (priv->r_debug == 0)
priv->r_debug = get_r_debug (pid, is_elf64);
/* We failed to find DT_DEBUG. Such situation will not change for this
inferior - do not retry it. Report it to GDB as E01, see for the reasons
at the GDB solib-svr4.c side. */
if (priv->r_debug == (CORE_ADDR) -1)
return -1;
if (priv->r_debug == 0)
{
document = xstrdup ("<library-list-svr4 version=\"1.0\"/>\n");
}
else
{
int allocated = 1024;
char *p;
const int ptr_size = is_elf64 ? 8 : 4;
CORE_ADDR lm_addr, lm_prev, l_name, l_addr, l_ld, l_next, l_prev;
int r_version, header_done = 0;
document = xmalloc (allocated);
strcpy (document, "<library-list-svr4 version=\"1.0\"");
p = document + strlen (document);
r_version = 0;
if (linux_read_memory (priv->r_debug + lmo->r_version_offset,
(unsigned char *) &r_version,
sizeof (r_version)) != 0
|| r_version != 1)
{
warning ("unexpected r_debug version %d", r_version);
goto done;
}
if (read_one_ptr (priv->r_debug + lmo->r_map_offset,
&lm_addr, ptr_size) != 0)
{
warning ("unable to read r_map from 0x%lx",
(long) priv->r_debug + lmo->r_map_offset);
goto done;
}
lm_prev = 0;
while (read_one_ptr (lm_addr + lmo->l_name_offset,
&l_name, ptr_size) == 0
&& read_one_ptr (lm_addr + lmo->l_addr_offset,
&l_addr, ptr_size) == 0
&& read_one_ptr (lm_addr + lmo->l_ld_offset,
&l_ld, ptr_size) == 0
&& read_one_ptr (lm_addr + lmo->l_prev_offset,
&l_prev, ptr_size) == 0
&& read_one_ptr (lm_addr + lmo->l_next_offset,
&l_next, ptr_size) == 0)
{
unsigned char libname[PATH_MAX];
if (lm_prev != l_prev)
{
warning ("Corrupted shared library list: 0x%lx != 0x%lx",
(long) lm_prev, (long) l_prev);
break;
}
/* Not checking for error because reading may stop before
we've got PATH_MAX worth of characters. */
libname[0] = '\0';
linux_read_memory (l_name, libname, sizeof (libname) - 1);
libname[sizeof (libname) - 1] = '\0';
if (libname[0] != '\0')
{
/* 6x the size for xml_escape_text below. */
size_t len = 6 * strlen ((char *) libname);
char *name;
if (!header_done)
{
/* Terminate `<library-list-svr4'. */
*p++ = '>';
header_done = 1;
}
while (allocated < p - document + len + 200)
{
/* Expand to guarantee sufficient storage. */
uintptr_t document_len = p - document;
document = xrealloc (document, 2 * allocated);
allocated *= 2;
p = document + document_len;
}
name = xml_escape_text ((char *) libname);
p += sprintf (p, "<library name=\"%s\" lm=\"0x%lx\" "
"l_addr=\"0x%lx\" l_ld=\"0x%lx\"/>",
name, (unsigned long) lm_addr,
(unsigned long) l_addr, (unsigned long) l_ld);
free (name);
}
else if (lm_prev == 0)
{
sprintf (p, " main-lm=\"0x%lx\"", (unsigned long) lm_addr);
p = p + strlen (p);
}
if (l_next == 0)
break;
lm_prev = lm_addr;
lm_addr = l_next;
}
done:
if (!header_done)
{
/* Empty list; terminate `<library-list-svr4'. */
strcpy (p, "/>");
}
else
strcpy (p, "</library-list-svr4>");
}
document_len = strlen (document);
if (offset < document_len)
document_len -= offset;
else
document_len = 0;
if (len > document_len)
len = document_len;
memcpy (readbuf, document + offset, len);
xfree (document);
return len;
}
#ifdef HAVE_LINUX_BTRACE
/* Enable branch tracing. */
static struct btrace_target_info *
linux_low_enable_btrace (ptid_t ptid)
{
struct btrace_target_info *tinfo;
tinfo = linux_enable_btrace (ptid);
if (tinfo != NULL)
tinfo->ptr_bits = register_size (0) * 8;
return tinfo;
}
/* Read branch trace data as btrace xml document. */
static void
linux_low_read_btrace (struct btrace_target_info *tinfo, struct buffer *buffer,
int type)
{
VEC (btrace_block_s) *btrace;
struct btrace_block *block;
int i;
btrace = linux_read_btrace (tinfo, type);
buffer_grow_str (buffer, "<!DOCTYPE btrace SYSTEM \"btrace.dtd\">\n");
buffer_grow_str (buffer, "<btrace version=\"1.0\">\n");
for (i = 0; VEC_iterate (btrace_block_s, btrace, i, block); i++)
buffer_xml_printf (buffer, "<block begin=\"0x%s\" end=\"0x%s\"/>\n",
paddress (block->begin), paddress (block->end));
buffer_grow_str (buffer, "</btrace>\n");
VEC_free (btrace_block_s, btrace);
}
#endif /* HAVE_LINUX_BTRACE */
static struct target_ops linux_target_ops = {
linux_create_inferior,
linux_attach,
linux_kill,
linux_detach,
linux_mourn,
linux_join,
linux_thread_alive,
linux_resume,
linux_wait,
linux_fetch_registers,
linux_store_registers,
linux_prepare_to_access_memory,
linux_done_accessing_memory,
linux_read_memory,
linux_write_memory,
linux_look_up_symbols,
linux_request_interrupt,
linux_read_auxv,
linux_insert_point,
linux_remove_point,
linux_stopped_by_watchpoint,
linux_stopped_data_address,
#if defined(__UCLIBC__) && defined(HAS_NOMMU)
linux_read_offsets,
#else
NULL,
#endif
#ifdef USE_THREAD_DB
thread_db_get_tls_address,
#else
NULL,
#endif
linux_qxfer_spu,
hostio_last_error_from_errno,
linux_qxfer_osdata,
linux_xfer_siginfo,
linux_supports_non_stop,
linux_async,
linux_start_non_stop,
linux_supports_multi_process,
#ifdef USE_THREAD_DB
thread_db_handle_monitor_command,
#else
NULL,
#endif
linux_common_core_of_thread,
linux_read_loadmap,
linux_process_qsupported,
linux_supports_tracepoints,
linux_read_pc,
linux_write_pc,
linux_thread_stopped,
NULL,
linux_pause_all,
linux_unpause_all,
linux_cancel_breakpoints,
linux_stabilize_threads,
linux_install_fast_tracepoint_jump_pad,
linux_emit_ops,
linux_supports_disable_randomization,
linux_get_min_fast_tracepoint_insn_len,
linux_qxfer_libraries_svr4,
linux_supports_agent,
#ifdef HAVE_LINUX_BTRACE
linux_supports_btrace,
linux_low_enable_btrace,
linux_disable_btrace,
linux_low_read_btrace,
#else
NULL,
NULL,
NULL,
NULL,
#endif
};
static void
linux_init_signals ()
{
/* FIXME drow/2002-06-09: As above, we should check with LinuxThreads
to find what the cancel signal actually is. */
#ifndef __ANDROID__ /* Bionic doesn't use SIGRTMIN the way glibc does. */
signal (__SIGRTMIN+1, SIG_IGN);
#endif
}
void
initialize_low (void)
{
struct sigaction sigchld_action;
memset (&sigchld_action, 0, sizeof (sigchld_action));
set_target_ops (&linux_target_ops);
set_breakpoint_data (the_low_target.breakpoint,
the_low_target.breakpoint_len);
linux_init_signals ();
linux_test_for_tracefork ();
linux_ptrace_init_warnings ();
#ifdef HAVE_LINUX_REGSETS
for (num_regsets = 0; target_regsets[num_regsets].size >= 0; num_regsets++)
;
disabled_regsets = xmalloc (num_regsets);
#endif
sigchld_action.sa_handler = sigchld_handler;
sigemptyset (&sigchld_action.sa_mask);
sigchld_action.sa_flags = SA_RESTART;
sigaction (SIGCHLD, &sigchld_action, NULL);
}
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