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cf424aef0a
- Use signal frame sniffers that look for the signal trampoline instruction sequence to detect most signal frames. - FreeBSD kernels between 9.2 and 10.1 inclusive do not include the signal trampoline code in process core dumps. To detect signal frames for core dumps under these kernels, use the kern.proc.sigtramp.<pid> sysctl to fetch the location of the signal trampoline in the gdb process and assume that PC values within this location are signal frames. This depends on that location being identical for all binaries. gdb/ChangeLog: 2015-02-25 John Baldwin <jhb@FreeBSD.org> * amd64fbsd-nat.c: Include sys/user.h. (_initialize_amd64fbsd_nat): Use the KERN_PROC_SIGTRAMP sysctl instead of KERN_PS_STRINGS to locate the signal trampoline. * i386fbsd-nat.c: Include sys/user.h. (_initialize_i386fbsd_nat): Use the KERN_PROC_SIGTRAMP sysctl instead of KERN_PS_STRINGS to locate the signal trampoline. * amd64fbsd-tdep.c (amd64fbsd_sigtramp_code): New. (amd64fbsd_sigtramp_p): New. (amd64fbsd_sigtramp_start_addr, amd64fbsd_sigtramp_end_addr): No longer set default values. (amd64fbsd_init_abi): Set "sigtramp_p" to "amd64fbsd_sigtramp_p". * i386fbsd-tdep.c (i386fbsd_sigtramp_start) (i386fbsd_sigtramp_middle, i386fbsd_sigtramp_end) (i386fbsd_freebsd4_sigtramp_start) (i386fbsd_freebsd4_sigtramp_middle) (i386fbsd_freebsd4_sigtramp_end, i386fbsd_osigtramp_start) (i386fbsd_osigtramp_middle, i386fbsd_osigtramp_end): New. (i386fbsd_sigtramp_p): New. (i386fbsd_sigtramp_start_addr, i386fbsd_sigtramp_end_addr): No longer set default values. (i386fbsd_init_abi): Set "sigtramp_p" to "i386fbsd_sigtramp_p".
178 lines
5.6 KiB
C
178 lines
5.6 KiB
C
/* Native-dependent code for FreeBSD/i386.
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Copyright (C) 2001-2015 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 3 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, see <http://www.gnu.org/licenses/>. */
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#include "defs.h"
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#include "inferior.h"
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#include "regcache.h"
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#include "target.h"
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#include <sys/types.h>
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#include <sys/ptrace.h>
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#include <sys/sysctl.h>
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#include <sys/user.h>
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#include "fbsd-nat.h"
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#include "i386-tdep.h"
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#include "x86-nat.h"
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#include "i386bsd-nat.h"
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/* Resume execution of the inferior process. If STEP is nonzero,
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single-step it. If SIGNAL is nonzero, give it that signal. */
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static void
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i386fbsd_resume (struct target_ops *ops,
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ptid_t ptid, int step, enum gdb_signal signal)
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{
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pid_t pid = ptid_get_pid (ptid);
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int request = PT_STEP;
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if (pid == -1)
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/* Resume all threads. This only gets used in the non-threaded
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case, where "resume all threads" and "resume inferior_ptid" are
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the same. */
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pid = ptid_get_pid (inferior_ptid);
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if (!step)
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{
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struct regcache *regcache = get_current_regcache ();
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ULONGEST eflags;
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/* Workaround for a bug in FreeBSD. Make sure that the trace
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flag is off when doing a continue. There is a code path
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through the kernel which leaves the flag set when it should
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have been cleared. If a process has a signal pending (such
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as SIGALRM) and we do a PT_STEP, the process never really has
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a chance to run because the kernel needs to notify the
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debugger that a signal is being sent. Therefore, the process
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never goes through the kernel's trap() function which would
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normally clear it. */
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regcache_cooked_read_unsigned (regcache, I386_EFLAGS_REGNUM,
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&eflags);
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if (eflags & 0x0100)
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regcache_cooked_write_unsigned (regcache, I386_EFLAGS_REGNUM,
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eflags & ~0x0100);
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request = PT_CONTINUE;
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}
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/* An addres of (caddr_t) 1 tells ptrace to continue from where it
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was. (If GDB wanted it to start some other way, we have already
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written a new PC value to the child.) */
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if (ptrace (request, pid, (caddr_t) 1,
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gdb_signal_to_host (signal)) == -1)
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perror_with_name (("ptrace"));
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}
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/* Support for debugging kernel virtual memory images. */
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#include <machine/pcb.h>
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#include "bsd-kvm.h"
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static int
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i386fbsd_supply_pcb (struct regcache *regcache, struct pcb *pcb)
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{
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/* The following is true for FreeBSD 4.7:
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The pcb contains %eip, %ebx, %esp, %ebp, %esi, %edi and %gs.
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This accounts for all callee-saved registers specified by the
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psABI and then some. Here %esp contains the stack pointer at the
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point just after the call to cpu_switch(). From this information
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we reconstruct the register state as it would look when we just
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returned from cpu_switch(). */
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/* The stack pointer shouldn't be zero. */
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if (pcb->pcb_esp == 0)
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return 0;
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pcb->pcb_esp += 4;
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regcache_raw_supply (regcache, I386_EDI_REGNUM, &pcb->pcb_edi);
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regcache_raw_supply (regcache, I386_ESI_REGNUM, &pcb->pcb_esi);
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regcache_raw_supply (regcache, I386_EBP_REGNUM, &pcb->pcb_ebp);
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regcache_raw_supply (regcache, I386_ESP_REGNUM, &pcb->pcb_esp);
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regcache_raw_supply (regcache, I386_EBX_REGNUM, &pcb->pcb_ebx);
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regcache_raw_supply (regcache, I386_EIP_REGNUM, &pcb->pcb_eip);
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regcache_raw_supply (regcache, I386_GS_REGNUM, &pcb->pcb_gs);
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return 1;
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}
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/* Prevent warning from -Wmissing-prototypes. */
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void _initialize_i386fbsd_nat (void);
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void
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_initialize_i386fbsd_nat (void)
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{
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struct target_ops *t;
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/* Add some extra features to the common *BSD/i386 target. */
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t = i386bsd_target ();
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#ifdef HAVE_PT_GETDBREGS
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x86_use_watchpoints (t);
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x86_dr_low.set_control = i386bsd_dr_set_control;
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x86_dr_low.set_addr = i386bsd_dr_set_addr;
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x86_dr_low.get_addr = i386bsd_dr_get_addr;
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x86_dr_low.get_status = i386bsd_dr_get_status;
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x86_dr_low.get_control = i386bsd_dr_get_control;
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x86_set_debug_register_length (4);
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#endif /* HAVE_PT_GETDBREGS */
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t->to_resume = i386fbsd_resume;
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t->to_pid_to_exec_file = fbsd_pid_to_exec_file;
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t->to_find_memory_regions = fbsd_find_memory_regions;
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add_target (t);
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/* Support debugging kernel virtual memory images. */
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bsd_kvm_add_target (i386fbsd_supply_pcb);
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#ifdef KERN_PROC_SIGTRAMP
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/* Normally signal frames are detected via i386fbsd_sigtramp_p.
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However, FreeBSD 9.2 through 10.1 do not include the page holding
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the signal code in core dumps. These releases do provide a
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kern.proc.sigtramp.<pid> sysctl that returns the location of the
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signal trampoline for a running process. We fetch the location
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of the current (gdb) process and use this to identify signal
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frames in core dumps from these releases. */
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{
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int mib[4];
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struct kinfo_sigtramp kst;
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size_t len;
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mib[0] = CTL_KERN;
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mib[1] = KERN_PROC;
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mib[2] = KERN_PROC_SIGTRAMP;
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mib[3] = getpid ();
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len = sizeof (kst);
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if (sysctl (mib, 4, &kst, &len, NULL, 0) == 0)
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{
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i386fbsd_sigtramp_start_addr = (uintptr_t) kst.ksigtramp_start;
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i386fbsd_sigtramp_end_addr = (uintptr_t) kst.ksigtramp_end;
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}
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}
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#endif
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}
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