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1104 lines
28 KiB
C
1104 lines
28 KiB
C
/* Multi-threaded debugging support for Linux (LWP layer).
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Copyright 2000, 2001 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include "defs.h"
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#include "gdb_assert.h"
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#include <errno.h>
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#include <signal.h>
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#include <sys/ptrace.h>
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#include "gdb_wait.h"
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#include "gdbthread.h"
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#include "inferior.h"
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#include "target.h"
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#include "regcache.h"
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#define DEBUG 1
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#if DEBUG
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extern const char *strsignal (int sig);
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#endif
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/* On Linux there are no real LWP's. The closest thing to LWP's are
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processes sharing the same VM space. A multi-threaded process is
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basically a group of such processes. However, such a grouping is
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almost entirely a user-space issue; the kernel doesn't enforce such
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a grouping at all (this might change in the future). In general,
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we'll rely on the threads library (i.e. the LinuxThreads library)
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to provide such a grouping.
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It is perfectly well possible to write a multi-threaded application
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without the assistance of a threads library, by using the clone
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system call directly. This module should be able to give some
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rudimentary support for debugging such applications if developers
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specify the CLONE_PTRACE flag in the clone system call, and are
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using Linux 2.4 or above.
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Note that there are some peculiarities in Linux that affect this
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code:
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- In general one should specify the __WCLONE flag to waitpid in
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order to make it report events for any of the cloned processes
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(and leave it out for the initial process). However, if a cloned
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process has exited the exit status is only reported if the
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__WCLONE flag is absent. Linux 2.4 has a __WALL flag, but we
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cannot use it since GDB must work on older systems too.
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- When a traced, cloned process exits and is waited for by the
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debugger, the kernel reassigns it to the origional parent and
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keeps it around as a "zombie". Somehow, the LinuxThreads library
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doesn't notice this, which leads to the "zombie problem": When
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debugged a multi-threaded process that spawns a lot of threads
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will run out of processes, even if the threads exit, because the
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"zombies" stay around. */
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/* Structure describing a LWP. */
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struct lwp_info
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{
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/* The process id of the LWP. This is a combination of the LWP id
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and overall process id. */
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int pid;
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/* Non-zero if we sent this LWP a SIGSTOP (but the LWP didn't report
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it back yet). */
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int signalled;
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/* Non-zero if this LWP is stopped. */
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int stopped;
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/* If non-zero, a pending wait status. */
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int status;
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/* Non-zero if we were stepping this LWP. */
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int step;
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/* Next LWP in list. */
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struct lwp_info *next;
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};
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/* List of known LWPs. */
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static struct lwp_info *lwp_list;
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/* Number of LWPs in the list. */
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static int num_lwps;
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/* Non-zero if we're running in "threaded" mode. */
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static int threaded;
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#ifndef TIDGET
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#define TIDGET(PID) (((PID) & 0x7fffffff) >> 16)
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#define PIDGET(PID) (((PID) & 0xffff))
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#define MERGEPID(PID, TID) (((PID) & 0xffff) | ((TID) << 16))
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#endif
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#define THREAD_FLAG 0x80000000
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#define is_lwp(pid) (((pid) & THREAD_FLAG) == 0 && TIDGET (pid))
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#define GET_LWP(pid) TIDGET (pid)
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#define GET_PID(pid) PIDGET (pid)
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#define BUILD_LWP(tid, pid) MERGEPID (pid, tid)
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#define is_cloned(pid) (GET_LWP (pid) != GET_PID (pid))
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/* If the last reported event was a SIGTRAP, this variable is set to
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the process id of the LWP/thread that got it. */
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int trap_pid;
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/* This module's target-specific operations. */
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static struct target_ops lin_lwp_ops;
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/* The standard child operations. */
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extern struct target_ops child_ops;
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/* Since we cannot wait (in lin_lwp_wait) for the initial process and
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any cloned processes with a single call to waitpid, we have to use
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use the WNOHANG flag and call waitpid in a loop. To optimize
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things a bit we use `sigsuspend' to wake us up when a process has
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something to report (it will send us a SIGCHLD if it has). To make
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this work we have to juggle with the signal mask. We save the
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origional signal mask such that we can restore it before creating a
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new process in order to avoid blocking certain signals in the
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inferior. We then block SIGCHLD during the waitpid/sigsuspend
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loop. */
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/* Origional signal mask. */
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static sigset_t normal_mask;
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/* Signal mask for use with sigsuspend in lin_lwp_wait, initialized in
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_initialize_lin_lwp. */
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static sigset_t suspend_mask;
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/* Signals to block to make that sigsuspend work. */
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static sigset_t blocked_mask;
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/* Prototypes for local functions. */
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static void lin_lwp_mourn_inferior (void);
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/* Initialize the list of LWPs. */
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static void
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init_lwp_list (void)
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{
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struct lwp_info *lp, *lpnext;
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for (lp = lwp_list; lp; lp = lpnext)
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{
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lpnext = lp->next;
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xfree (lp);
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}
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lwp_list = NULL;
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num_lwps = 0;
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threaded = 0;
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}
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/* Add the LWP specified by PID to the list. If this causes the
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number of LWPs to become larger than one, go into "threaded" mode.
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Return a pointer to the structure describing the new LWP. */
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static struct lwp_info *
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add_lwp (int pid)
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{
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struct lwp_info *lp;
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gdb_assert (is_lwp (pid));
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lp = (struct lwp_info *) xmalloc (sizeof (struct lwp_info));
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memset (lp, 0, sizeof (struct lwp_info));
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lp->pid = pid;
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lp->next = lwp_list;
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lwp_list = lp;
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if (++num_lwps > 1)
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threaded = 1;
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return lp;
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}
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/* Remove the LWP specified by PID from the list. */
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static void
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delete_lwp (int pid)
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{
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struct lwp_info *lp, *lpprev;
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lpprev = NULL;
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for (lp = lwp_list; lp; lpprev = lp, lp = lp->next)
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if (lp->pid == pid)
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break;
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if (!lp)
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return;
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/* We don't go back to "non-threaded" mode if the number of threads
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becomes less than two. */
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num_lwps--;
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if (lpprev)
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lpprev->next = lp->next;
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else
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lwp_list = lp->next;
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xfree (lp);
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}
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/* Return a pointer to the structure describing the LWP corresponding
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to PID. If no corresponding LWP could be found, return NULL. */
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static struct lwp_info *
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find_lwp_pid (int pid)
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{
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struct lwp_info *lp;
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if (is_lwp (pid))
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pid = GET_LWP (pid);
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for (lp = lwp_list; lp; lp = lp->next)
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if (pid == GET_LWP (lp->pid))
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return lp;
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return NULL;
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}
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/* Call CALLBACK with its second argument set to DATA for every LWP in
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the list. If CALLBACK returns 1 for a particular LWP, return a
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pointer to the structure describing that LWP immediately.
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Otherwise return NULL. */
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struct lwp_info *
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iterate_over_lwps (int (*callback) (struct lwp_info *, void *), void *data)
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{
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struct lwp_info *lp;
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for (lp = lwp_list; lp; lp = lp->next)
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if ((*callback) (lp, data))
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return lp;
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return NULL;
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}
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/* Helper functions. */
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static void
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restore_inferior_pid (void *arg)
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{
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int *saved_pid_ptr = arg;
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inferior_pid = *saved_pid_ptr;
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xfree (arg);
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}
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static struct cleanup *
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save_inferior_pid (void)
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{
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int *saved_pid_ptr;
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saved_pid_ptr = xmalloc (sizeof (int));
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*saved_pid_ptr = inferior_pid;
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return make_cleanup (restore_inferior_pid, saved_pid_ptr);
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}
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/* Implementation of the PREPARE_TO_PROCEED hook for the Linux LWP layer. */
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int
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lin_lwp_prepare_to_proceed (void)
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{
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if (trap_pid && inferior_pid != trap_pid)
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{
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/* Switched over from TRAP_PID. */
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CORE_ADDR stop_pc = read_pc ();
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CORE_ADDR trap_pc;
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/* Avoid switching where it wouldn't do any good, i.e. if both
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threads are at the same breakpoint. */
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trap_pc = read_pc_pid (trap_pid);
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if (trap_pc != stop_pc && breakpoint_here_p (trap_pc))
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{
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/* User hasn't deleted the breakpoint. Return non-zero, and
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switch back to TRAP_PID. */
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inferior_pid = trap_pid;
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/* FIXME: Is this stuff really necessary? */
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flush_cached_frames ();
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registers_changed ();
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return 1;
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}
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}
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return 0;
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}
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#if 0
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static void
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lin_lwp_open (char *args, int from_tty)
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{
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push_target (&lin_lwp_ops);
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}
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#endif
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/* Attach to the LWP specified by PID. If VERBOSE is non-zero, print
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a message telling the user that a new LWP has been added to the
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process. */
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void
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lin_lwp_attach_lwp (int pid, int verbose)
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{
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struct lwp_info *lp;
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gdb_assert (is_lwp (pid));
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if (verbose)
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printf_filtered ("[New %s]\n", target_pid_to_str (pid));
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if (ptrace (PTRACE_ATTACH, GET_LWP (pid), 0, 0) < 0)
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error ("Can't attach %s: %s", target_pid_to_str (pid), strerror (errno));
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lp = add_lwp (pid);
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lp->signalled = 1;
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}
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static void
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lin_lwp_attach (char *args, int from_tty)
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{
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/* FIXME: We should probably accept a list of process id's, and
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attach all of them. */
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error("Not implemented yet");
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}
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static void
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lin_lwp_detach (char *args, int from_tty)
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{
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/* FIXME: Provide implementation when we implement lin_lwp_attach. */
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error ("Not implemented yet");
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}
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struct private_thread_info
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{
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int lwpid;
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};
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/* Return non-zero if TP corresponds to the LWP specified by DATA
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(which is assumed to be a pointer to a `struct lwp_info'. */
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static int
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find_lwp_callback (struct thread_info *tp, void *data)
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{
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struct lwp_info *lp = data;
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if (tp->private->lwpid == GET_LWP (lp->pid))
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return 1;
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return 0;
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}
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/* Resume LP. */
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static int
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resume_callback (struct lwp_info *lp, void *data)
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{
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if (lp->stopped && lp->status == 0)
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{
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struct thread_info *tp;
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#if 1
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/* FIXME: kettenis/2000-08-26: This should really be handled
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properly by core GDB. */
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tp = find_thread_pid (lp->pid);
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if (tp == NULL)
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tp = iterate_over_threads (find_lwp_callback, lp);
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gdb_assert (tp);
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/* If we were previously stepping the thread, and now continue
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the thread we must invalidate the stepping range. However,
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if there is a step_resume breakpoint for this thread, we must
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preserve the stepping range to make it possible to continue
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stepping once we hit it. */
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if (tp->step_range_end && tp->step_resume_breakpoint == NULL)
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{
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gdb_assert (lp->step);
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tp->step_range_start = tp->step_range_end = 0;
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}
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#endif
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child_resume (GET_LWP (lp->pid), 0, TARGET_SIGNAL_0);
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lp->stopped = 0;
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lp->step = 0;
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}
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return 0;
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}
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static void
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lin_lwp_resume (int pid, int step, enum target_signal signo)
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{
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struct lwp_info *lp;
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int resume_all;
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/* Apparently the interpretation of PID is dependent on STEP: If
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STEP is non-zero, a specific PID means `step only this process
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id'. But if STEP is zero, then PID means `continue *all*
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processes, but give the signal only to this one'. */
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resume_all = (pid == -1) || !step;
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/* If PID is -1, it's the current inferior that should be
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handled special. */
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if (pid == -1)
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pid = inferior_pid;
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lp = find_lwp_pid (pid);
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if (lp)
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{
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pid = GET_LWP (lp->pid);
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/* Mark LWP as not stopped to prevent it from being continued by
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resume_callback. */
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lp->stopped = 0;
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/* Remember if we're stepping. */
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lp->step = step;
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/* If we have a pending wait status for this thread, there is no
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point in resuming the process. */
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if (lp->status)
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{
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/* FIXME: What should we do if we are supposed to continue
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this thread with a signal? */
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gdb_assert (signo == TARGET_SIGNAL_0);
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return;
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}
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}
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if (resume_all)
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iterate_over_lwps (resume_callback, NULL);
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child_resume (pid, step, signo);
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}
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/* Send a SIGSTOP to LP. */
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static int
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stop_callback (struct lwp_info *lp, void *data)
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{
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if (! lp->stopped && ! lp->signalled)
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{
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int ret;
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ret = kill (GET_LWP (lp->pid), SIGSTOP);
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gdb_assert (ret == 0);
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lp->signalled = 1;
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gdb_assert (lp->status == 0);
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}
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return 0;
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}
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/* Wait until LP is stopped. */
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static int
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stop_wait_callback (struct lwp_info *lp, void *data)
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{
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if (! lp->stopped && lp->signalled)
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{
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pid_t pid;
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int status;
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gdb_assert (lp->status == 0);
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pid = waitpid (GET_LWP (lp->pid), &status,
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is_cloned (lp->pid) ? __WCLONE : 0);
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if (pid == -1 && errno == ECHILD)
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/* OK, the proccess has disappeared. We'll catch the actual
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exit event in lin_lwp_wait. */
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return 0;
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gdb_assert (pid == GET_LWP (lp->pid));
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if (WIFEXITED (status) || WIFSIGNALED (status))
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{
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gdb_assert (num_lwps > 1);
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if (in_thread_list (lp->pid))
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{
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/* Core GDB cannot deal with us deleting the current
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||
thread. */
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if (lp->pid != inferior_pid)
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delete_thread (lp->pid);
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printf_unfiltered ("[%s exited]\n",
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target_pid_to_str (lp->pid));
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}
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#if DEBUG
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||
printf ("%s exited.\n", target_pid_to_str (lp->pid));
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||
#endif
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delete_lwp (lp->pid);
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return 0;
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}
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gdb_assert (WIFSTOPPED (status));
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||
lp->stopped = 1;
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if (WSTOPSIG (status) != SIGSTOP)
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||
{
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||
if (WSTOPSIG (status) == SIGTRAP
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||
&& breakpoint_inserted_here_p (read_pc_pid (pid)
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||
- DECR_PC_AFTER_BREAK))
|
||
{
|
||
/* 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
|
||
thread will have already tripped on it. */
|
||
#if DEBUG
|
||
printf ("Tripped breakpoint at %lx in LWP %d"
|
||
" while waiting for SIGSTOP.\n",
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||
(long) read_pc_pid (lp->pid), pid);
|
||
#endif
|
||
/* Set the PC to before the trap. */
|
||
if (DECR_PC_AFTER_BREAK)
|
||
write_pc_pid (read_pc_pid (pid) - DECR_PC_AFTER_BREAK, pid);
|
||
}
|
||
else
|
||
{
|
||
#if DEBUG
|
||
printf ("Received %s in LWP %d while waiting for SIGSTOP.\n",
|
||
strsignal (WSTOPSIG (status)), pid);
|
||
#endif
|
||
/* The thread was stopped with a signal other than
|
||
SIGSTOP, and didn't accidentiliy trip a breakpoint.
|
||
Record the wait status. */
|
||
lp->status = status;
|
||
}
|
||
}
|
||
else
|
||
{
|
||
/* We caught the SIGSTOP that we intended to catch, so
|
||
there's no SIGSTOP pending. */
|
||
lp->signalled = 0;
|
||
}
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
/* Return non-zero if LP has a wait status pending. */
|
||
|
||
static int
|
||
status_callback (struct lwp_info *lp, void *data)
|
||
{
|
||
return (lp->status != 0);
|
||
}
|
||
|
||
/* Return non-zero if LP isn't stopped. */
|
||
|
||
static int
|
||
running_callback (struct lwp_info *lp, void *data)
|
||
{
|
||
return (lp->stopped == 0);
|
||
}
|
||
|
||
static int
|
||
lin_lwp_wait (int pid, struct target_waitstatus *ourstatus)
|
||
{
|
||
struct lwp_info *lp = NULL;
|
||
int options = 0;
|
||
int status = 0;
|
||
|
||
/* Make sure SIGCHLD is blocked. */
|
||
if (! sigismember (&blocked_mask, SIGCHLD))
|
||
{
|
||
sigaddset (&blocked_mask, SIGCHLD);
|
||
sigprocmask (SIG_BLOCK, &blocked_mask, NULL);
|
||
}
|
||
|
||
retry:
|
||
|
||
/* First check if there is a LWP with a wait status pending. */
|
||
if (pid == -1)
|
||
{
|
||
/* Any LWP will do. */
|
||
lp = iterate_over_lwps (status_callback, NULL);
|
||
if (lp)
|
||
{
|
||
#if DEBUG
|
||
printf ("Using pending wait status for LWP %d.\n",
|
||
GET_LWP (lp->pid));
|
||
#endif
|
||
status = lp->status;
|
||
lp->status = 0;
|
||
}
|
||
|
||
/* But if we don't fine one, we'll have to wait, and check both
|
||
cloned and uncloned processes. We start with the cloned
|
||
processes. */
|
||
options = __WCLONE | WNOHANG;
|
||
}
|
||
else if (is_lwp (pid))
|
||
{
|
||
#if DEBUG
|
||
printf ("Waiting for specific LWP %d.\n", GET_LWP (pid));
|
||
#endif
|
||
/* We have a specific LWP to check. */
|
||
lp = find_lwp_pid (GET_LWP (pid));
|
||
gdb_assert (lp);
|
||
status = lp->status;
|
||
lp->status = 0;
|
||
#if DEBUG
|
||
if (status)
|
||
printf ("Using pending wait status for LWP %d.\n",
|
||
GET_LWP (lp->pid));
|
||
#endif
|
||
|
||
/* If we have to wait, take into account whether PID is a cloned
|
||
process or not. And we have to convert it to something that
|
||
the layer beneath us can understand. */
|
||
options = is_cloned (lp->pid) ? __WCLONE : 0;
|
||
pid = GET_LWP (pid);
|
||
}
|
||
|
||
if (status && lp->signalled)
|
||
{
|
||
/* A pending SIGSTOP may interfere with the normal stream of
|
||
events. In a typical case where interference is a problem,
|
||
we have a SIGSTOP signal pending for LWP A while
|
||
single-stepping it, encounter an event in LWP B, and take the
|
||
pending SIGSTOP while trying to stop LWP A. After processing
|
||
the event in LWP B, LWP A is continued, and we'll never see
|
||
the SIGTRAP associated with the last time we were
|
||
single-stepping LWP A. */
|
||
|
||
/* Resume the thread. It should halt immediately returning the
|
||
pending SIGSTOP. */
|
||
child_resume (GET_LWP (lp->pid), lp->step, TARGET_SIGNAL_0);
|
||
lp->stopped = 0;
|
||
|
||
/* This should catch the pending SIGSTOP. */
|
||
stop_wait_callback (lp, NULL);
|
||
}
|
||
|
||
set_sigint_trap (); /* Causes SIGINT to be passed on to the
|
||
attached process. */
|
||
set_sigio_trap ();
|
||
|
||
while (status == 0)
|
||
{
|
||
pid_t lwpid;
|
||
|
||
lwpid = waitpid (pid, &status, options);
|
||
if (lwpid > 0)
|
||
{
|
||
gdb_assert (pid == -1 || lwpid == pid);
|
||
|
||
lp = find_lwp_pid (lwpid);
|
||
if (! lp)
|
||
{
|
||
lp = add_lwp (BUILD_LWP (lwpid, inferior_pid));
|
||
if (threaded)
|
||
{
|
||
gdb_assert (WIFSTOPPED (status)
|
||
&& WSTOPSIG (status) == SIGSTOP);
|
||
lp->signalled = 1;
|
||
|
||
if (! in_thread_list (inferior_pid))
|
||
{
|
||
inferior_pid = BUILD_LWP (inferior_pid, inferior_pid);
|
||
add_thread (inferior_pid);
|
||
}
|
||
|
||
add_thread (lp->pid);
|
||
printf_unfiltered ("[New %s]\n",
|
||
target_pid_to_str (lp->pid));
|
||
}
|
||
}
|
||
|
||
/* Make sure we don't report a TARGET_WAITKIND_EXITED or
|
||
TARGET_WAITKIND_SIGNALLED event if there are still LWP's
|
||
left in the process. */
|
||
if ((WIFEXITED (status) || WIFSIGNALED (status)) && num_lwps > 1)
|
||
{
|
||
if (in_thread_list (lp->pid))
|
||
{
|
||
/* Core GDB cannot deal with us deleting the current
|
||
thread. */
|
||
if (lp->pid != inferior_pid)
|
||
delete_thread (lp->pid);
|
||
printf_unfiltered ("[%s exited]\n",
|
||
target_pid_to_str (lp->pid));
|
||
}
|
||
#if DEBUG
|
||
printf ("%s exited.\n", target_pid_to_str (lp->pid));
|
||
#endif
|
||
delete_lwp (lp->pid);
|
||
|
||
/* Make sure there is at least one thread running. */
|
||
gdb_assert (iterate_over_lwps (running_callback, NULL));
|
||
|
||
/* Discard the event. */
|
||
status = 0;
|
||
continue;
|
||
}
|
||
|
||
/* Make sure we don't report a SIGSTOP that we sent
|
||
ourselves in an attempt to stop an LWP. */
|
||
if (lp->signalled && WIFSTOPPED (status)
|
||
&& WSTOPSIG (status) == SIGSTOP)
|
||
{
|
||
#if DEBUG
|
||
printf ("Delayed SIGSTOP caught for %s.\n",
|
||
target_pid_to_str (lp->pid));
|
||
#endif
|
||
/* This is a delayed SIGSTOP. */
|
||
lp->signalled = 0;
|
||
|
||
child_resume (GET_LWP (lp->pid), lp->step, TARGET_SIGNAL_0);
|
||
lp->stopped = 0;
|
||
|
||
/* Discard the event. */
|
||
status = 0;
|
||
continue;
|
||
}
|
||
|
||
break;
|
||
}
|
||
|
||
if (pid == -1)
|
||
{
|
||
/* Alternate between checking cloned and uncloned processes. */
|
||
options ^= __WCLONE;
|
||
|
||
/* And suspend every time we have checked both. */
|
||
if (options & __WCLONE)
|
||
sigsuspend (&suspend_mask);
|
||
}
|
||
|
||
/* We shouldn't end up here unless we want to try again. */
|
||
gdb_assert (status == 0);
|
||
}
|
||
|
||
clear_sigio_trap ();
|
||
clear_sigint_trap ();
|
||
|
||
gdb_assert (lp);
|
||
|
||
/* Don't report signals that GDB isn't interested in, such as
|
||
signals that are neither printed nor stopped upon. Stopping all
|
||
threads can be a bit time-consuming so if we want decent
|
||
performance with heavily multi-threaded programs, especially when
|
||
they're using a high frequency timer, we'd better avoid it if we
|
||
can. */
|
||
|
||
if (WIFSTOPPED (status))
|
||
{
|
||
int signo = target_signal_from_host (WSTOPSIG (status));
|
||
|
||
if (signal_stop_state (signo) == 0
|
||
&& signal_print_state (signo) == 0
|
||
&& signal_pass_state (signo) == 1)
|
||
{
|
||
child_resume (GET_LWP (lp->pid), lp->step, signo);
|
||
lp->stopped = 0;
|
||
status = 0;
|
||
goto retry;
|
||
}
|
||
}
|
||
|
||
/* This LWP is stopped now. */
|
||
lp->stopped = 1;
|
||
|
||
/* Now stop all other LWP's ... */
|
||
iterate_over_lwps (stop_callback, NULL);
|
||
|
||
/* ... and wait until all of them have reported back that they're no
|
||
longer running. */
|
||
iterate_over_lwps (stop_wait_callback, NULL);
|
||
|
||
/* If we're not running in "threaded" mode, we'll report the bare
|
||
process id. */
|
||
|
||
if (WIFSTOPPED (status) && WSTOPSIG (status) == SIGTRAP)
|
||
trap_pid = (threaded ? lp->pid : GET_LWP (lp->pid));
|
||
else
|
||
trap_pid = 0;
|
||
|
||
store_waitstatus (ourstatus, status);
|
||
return (threaded ? lp->pid : GET_LWP (lp->pid));
|
||
}
|
||
|
||
static int
|
||
kill_callback (struct lwp_info *lp, void *data)
|
||
{
|
||
ptrace (PTRACE_KILL, GET_LWP (lp->pid), 0, 0);
|
||
return 0;
|
||
}
|
||
|
||
static int
|
||
kill_wait_callback (struct lwp_info *lp, void *data)
|
||
{
|
||
pid_t pid;
|
||
|
||
/* We must make sure that there are no pending events (delayed
|
||
SIGSTOPs, pending SIGTRAPs, etc.) to make sure the current
|
||
program doesn't interfere with any following debugging session. */
|
||
|
||
/* For cloned processes we must check both with __WCLONE and
|
||
without, since the exit status of a cloned process isn't reported
|
||
with __WCLONE. */
|
||
if (is_cloned (lp->pid))
|
||
{
|
||
do
|
||
{
|
||
pid = waitpid (GET_LWP (lp->pid), NULL, __WCLONE);
|
||
}
|
||
while (pid == GET_LWP (lp->pid));
|
||
|
||
gdb_assert (pid == -1 && errno == ECHILD);
|
||
}
|
||
|
||
do
|
||
{
|
||
pid = waitpid (GET_LWP (lp->pid), NULL, 0);
|
||
}
|
||
while (pid == GET_LWP (lp->pid));
|
||
|
||
gdb_assert (pid == -1 && errno == ECHILD);
|
||
return 0;
|
||
}
|
||
|
||
static void
|
||
lin_lwp_kill (void)
|
||
{
|
||
/* Kill all LWP's ... */
|
||
iterate_over_lwps (kill_callback, NULL);
|
||
|
||
/* ... and wait until we've flushed all events. */
|
||
iterate_over_lwps (kill_wait_callback, NULL);
|
||
|
||
target_mourn_inferior ();
|
||
}
|
||
|
||
static void
|
||
lin_lwp_create_inferior (char *exec_file, char *allargs, char **env)
|
||
{
|
||
struct target_ops *target_beneath;
|
||
|
||
init_lwp_list ();
|
||
|
||
#if 0
|
||
target_beneath = find_target_beneath (&lin_lwp_ops);
|
||
#else
|
||
target_beneath = &child_ops;
|
||
#endif
|
||
target_beneath->to_create_inferior (exec_file, allargs, env);
|
||
}
|
||
|
||
static void
|
||
lin_lwp_mourn_inferior (void)
|
||
{
|
||
struct target_ops *target_beneath;
|
||
|
||
init_lwp_list ();
|
||
|
||
trap_pid = 0;
|
||
|
||
/* Restore the origional signal mask. */
|
||
sigprocmask (SIG_SETMASK, &normal_mask, NULL);
|
||
sigemptyset (&blocked_mask);
|
||
|
||
#if 0
|
||
target_beneath = find_target_beneath (&lin_lwp_ops);
|
||
#else
|
||
target_beneath = &child_ops;
|
||
#endif
|
||
target_beneath->to_mourn_inferior ();
|
||
}
|
||
|
||
static void
|
||
lin_lwp_fetch_registers (int regno)
|
||
{
|
||
struct cleanup *old_chain = save_inferior_pid ();
|
||
|
||
if (is_lwp (inferior_pid))
|
||
inferior_pid = GET_LWP (inferior_pid);
|
||
|
||
fetch_inferior_registers (regno);
|
||
|
||
do_cleanups (old_chain);
|
||
}
|
||
|
||
static void
|
||
lin_lwp_store_registers (int regno)
|
||
{
|
||
struct cleanup *old_chain = save_inferior_pid ();
|
||
|
||
if (is_lwp (inferior_pid))
|
||
inferior_pid = GET_LWP (inferior_pid);
|
||
|
||
store_inferior_registers (regno);
|
||
|
||
do_cleanups (old_chain);
|
||
}
|
||
|
||
static int
|
||
lin_lwp_xfer_memory (CORE_ADDR memaddr, char *myaddr, int len, int write,
|
||
struct mem_attrib *attrib,
|
||
struct target_ops *target)
|
||
{
|
||
struct cleanup *old_chain = save_inferior_pid ();
|
||
int xfer;
|
||
|
||
if (is_lwp (inferior_pid))
|
||
inferior_pid = GET_LWP (inferior_pid);
|
||
|
||
xfer = child_xfer_memory (memaddr, myaddr, len, write, attrib, target);
|
||
|
||
do_cleanups (old_chain);
|
||
return xfer;
|
||
}
|
||
|
||
static int
|
||
lin_lwp_thread_alive (int pid)
|
||
{
|
||
gdb_assert (is_lwp (pid));
|
||
|
||
errno = 0;
|
||
ptrace (PTRACE_PEEKUSER, GET_LWP (pid), 0, 0);
|
||
if (errno)
|
||
return 0;
|
||
|
||
return 1;
|
||
}
|
||
|
||
static char *
|
||
lin_lwp_pid_to_str (int pid)
|
||
{
|
||
static char buf[64];
|
||
|
||
if (is_lwp (pid))
|
||
{
|
||
snprintf (buf, sizeof (buf), "LWP %d", GET_LWP (pid));
|
||
return buf;
|
||
}
|
||
|
||
return normal_pid_to_str (pid);
|
||
}
|
||
|
||
static void
|
||
init_lin_lwp_ops (void)
|
||
{
|
||
#if 0
|
||
lin_lwp_ops.to_open = lin_lwp_open;
|
||
#endif
|
||
lin_lwp_ops.to_shortname = "lwp-layer";
|
||
lin_lwp_ops.to_longname = "lwp-layer";
|
||
lin_lwp_ops.to_doc = "Low level threads support (LWP layer)";
|
||
lin_lwp_ops.to_attach = lin_lwp_attach;
|
||
lin_lwp_ops.to_detach = lin_lwp_detach;
|
||
lin_lwp_ops.to_resume = lin_lwp_resume;
|
||
lin_lwp_ops.to_wait = lin_lwp_wait;
|
||
lin_lwp_ops.to_fetch_registers = lin_lwp_fetch_registers;
|
||
lin_lwp_ops.to_store_registers = lin_lwp_store_registers;
|
||
lin_lwp_ops.to_xfer_memory = lin_lwp_xfer_memory;
|
||
lin_lwp_ops.to_kill = lin_lwp_kill;
|
||
lin_lwp_ops.to_create_inferior = lin_lwp_create_inferior;
|
||
lin_lwp_ops.to_mourn_inferior = lin_lwp_mourn_inferior;
|
||
lin_lwp_ops.to_thread_alive = lin_lwp_thread_alive;
|
||
lin_lwp_ops.to_pid_to_str = lin_lwp_pid_to_str;
|
||
lin_lwp_ops.to_stratum = thread_stratum;
|
||
lin_lwp_ops.to_has_thread_control = tc_schedlock;
|
||
lin_lwp_ops.to_magic = OPS_MAGIC;
|
||
}
|
||
|
||
static void
|
||
sigchld_handler (int signo)
|
||
{
|
||
/* Do nothing. The only reason for this handler is that it allows
|
||
us to use sigsuspend in lin_lwp_wait above to wait for the
|
||
arrival of a SIGCHLD. */
|
||
}
|
||
|
||
void
|
||
_initialize_lin_lwp (void)
|
||
{
|
||
struct sigaction action;
|
||
|
||
extern void thread_db_init (struct target_ops *);
|
||
|
||
init_lin_lwp_ops ();
|
||
add_target (&lin_lwp_ops);
|
||
thread_db_init (&lin_lwp_ops);
|
||
|
||
/* Save the origional signal mask. */
|
||
sigprocmask (SIG_SETMASK, NULL, &normal_mask);
|
||
|
||
action.sa_handler = sigchld_handler;
|
||
sigemptyset (&action.sa_mask);
|
||
action.sa_flags = 0;
|
||
sigaction (SIGCHLD, &action, NULL);
|
||
|
||
/* Make sure we don't block SIGCHLD during a sigsuspend. */
|
||
sigprocmask (SIG_SETMASK, NULL, &suspend_mask);
|
||
sigdelset (&suspend_mask, SIGCHLD);
|
||
|
||
sigemptyset (&blocked_mask);
|
||
}
|
||
|
||
|
||
/* FIXME: kettenis/2000-08-26: The stuff on this page is specific to
|
||
the LinuxThreads library and therefore doesn't really belong here. */
|
||
|
||
/* Read variable NAME in the target and return its value if found.
|
||
Otherwise return zero. It is assumed that the type of the variable
|
||
is `int'. */
|
||
|
||
static int
|
||
get_signo (const char *name)
|
||
{
|
||
struct minimal_symbol *ms;
|
||
int signo;
|
||
|
||
ms = lookup_minimal_symbol (name, NULL, NULL);
|
||
if (ms == NULL)
|
||
return 0;
|
||
|
||
if (target_read_memory (SYMBOL_VALUE_ADDRESS (ms), (char *) &signo,
|
||
sizeof (signo)) != 0)
|
||
return 0;
|
||
|
||
return signo;
|
||
}
|
||
|
||
/* Return the set of signals used by the threads library in *SET. */
|
||
|
||
void
|
||
lin_thread_get_thread_signals (sigset_t *set)
|
||
{
|
||
struct sigaction action;
|
||
int restart, cancel;
|
||
|
||
sigemptyset (set);
|
||
|
||
restart = get_signo ("__pthread_sig_restart");
|
||
if (restart == 0)
|
||
return;
|
||
|
||
cancel = get_signo ("__pthread_sig_cancel");
|
||
if (cancel == 0)
|
||
return;
|
||
|
||
sigaddset (set, restart);
|
||
sigaddset (set, cancel);
|
||
|
||
/* The LinuxThreads library makes terminating threads send a special
|
||
"cancel" signal instead of SIGCHLD. Make sure we catch those (to
|
||
prevent them from terminating GDB itself, which is likely to be
|
||
their default action) and treat them the same way as SIGCHLD. */
|
||
|
||
action.sa_handler = sigchld_handler;
|
||
sigemptyset (&action.sa_mask);
|
||
action.sa_flags = 0;
|
||
sigaction (cancel, &action, NULL);
|
||
|
||
/* We block the "cancel" signal throughout this code ... */
|
||
sigaddset (&blocked_mask, cancel);
|
||
sigprocmask (SIG_BLOCK, &blocked_mask, NULL);
|
||
|
||
/* ... except during a sigsuspend. */
|
||
sigdelset (&suspend_mask, cancel);
|
||
}
|