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/* Native-dependent code for FreeBSD/i386.
Copyright (C) 2001-2021 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
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 <>. */
#include "defs.h"
#include "inferior.h"
#include "regcache.h"
#include "target.h"
#include <sys/types.h>
#include <sys/ptrace.h>
#include <sys/sysctl.h>
#include <sys/user.h>
#include "fbsd-nat.h"
#include "i386-tdep.h"
#include "x86-nat.h"
#include "gdbsupport/x86-xstate.h"
#include "x86-bsd-nat.h"
#include "i386-bsd-nat.h"
class i386_fbsd_nat_target final
: public i386_bsd_nat_target<fbsd_nat_target>
/* Add some extra features to the common *BSD/i386 target. */
const struct target_desc *read_description () override;
void resume (ptid_t, int, enum gdb_signal) override;
bool supports_stopped_by_hw_breakpoint () override;
static i386_fbsd_nat_target the_i386_fbsd_nat_target;
/* Resume execution of the inferior process. If STEP is nonzero,
single-step it. If SIGNAL is nonzero, give it that signal. */
i386_fbsd_nat_target::resume (ptid_t ptid, int step, enum gdb_signal signal)
pid_t pid = ();
int request = PT_STEP;
if (pid == -1)
/* Resume all threads. This only gets used in the non-threaded
case, where "resume all threads" and "resume inferior_ptid" are
the same. */
pid = ();
if (!step)
struct regcache *regcache = get_current_regcache ();
ULONGEST eflags;
/* Workaround for a bug in FreeBSD. Make sure that the trace
flag is off when doing a continue. There is a code path
through the kernel which leaves the flag set when it should
have been cleared. If a process has a signal pending (such
as SIGALRM) and we do a PT_STEP, the process never really has
a chance to run because the kernel needs to notify the
debugger that a signal is being sent. Therefore, the process
never goes through the kernel's trap() function which would
normally clear it. */
regcache_cooked_read_unsigned (regcache, I386_EFLAGS_REGNUM,
if (eflags & 0x0100)
regcache_cooked_write_unsigned (regcache, I386_EFLAGS_REGNUM,
eflags & ~0x0100);
request = PT_CONTINUE;
/* An addres of (caddr_t) 1 tells ptrace to continue from where it
was. (If GDB wanted it to start some other way, we have already
written a new PC value to the child.) */
if (ptrace (request, pid, (caddr_t) 1,
gdb_signal_to_host (signal)) == -1)
perror_with_name (("ptrace"));
/* Support for debugging kernel virtual memory images. */
#include <machine/pcb.h>
#include "bsd-kvm.h"
static int
i386fbsd_supply_pcb (struct regcache *regcache, struct pcb *pcb)
/* The following is true for FreeBSD 4.7:
The pcb contains %eip, %ebx, %esp, %ebp, %esi, %edi and %gs.
This accounts for all callee-saved registers specified by the
psABI and then some. Here %esp contains the stack pointer at the
point just after the call to cpu_switch(). From this information
we reconstruct the register state as it would look when we just
returned from cpu_switch(). */
/* The stack pointer shouldn't be zero. */
if (pcb->pcb_esp == 0)
return 0;
pcb->pcb_esp += 4;
regcache->raw_supply (I386_EDI_REGNUM, &pcb->pcb_edi);
regcache->raw_supply (I386_ESI_REGNUM, &pcb->pcb_esi);
regcache->raw_supply (I386_EBP_REGNUM, &pcb->pcb_ebp);
regcache->raw_supply (I386_ESP_REGNUM, &pcb->pcb_esp);
regcache->raw_supply (I386_EBX_REGNUM, &pcb->pcb_ebx);
regcache->raw_supply (I386_EIP_REGNUM, &pcb->pcb_eip);
regcache->raw_supply (I386_GS_REGNUM, &pcb->pcb_gs);
return 1;
/* Implement the read_description method. */
const struct target_desc *
i386_fbsd_nat_target::read_description ()
static int xsave_probed;
static uint64_t xcr0;
if (!xsave_probed)
struct ptrace_xstate_info info;
if (ptrace (PT_GETXSTATE_INFO, (),
(PTRACE_TYPE_ARG3) &info, sizeof (info)) == 0)
x86bsd_xsave_len = info.xsave_len;
xcr0 = info.xsave_mask;
xsave_probed = 1;
if (x86bsd_xsave_len == 0)
return i386_target_description (xcr0, true);
/* Implement the supports_stopped_by_hw_breakpoints method. */
i386_fbsd_nat_target::supports_stopped_by_hw_breakpoint ()
return true;
void _initialize_i386fbsd_nat ();
_initialize_i386fbsd_nat ()
add_inf_child_target (&the_i386_fbsd_nat_target);
/* Support debugging kernel virtual memory images. */
bsd_kvm_add_target (i386fbsd_supply_pcb);
/* Normally signal frames are detected via i386fbsd_sigtramp_p.
However, FreeBSD 9.2 through 10.1 do not include the page holding
the signal code in core dumps. These releases do provide a
kern.proc.sigtramp.<pid> sysctl that returns the location of the
signal trampoline for a running process. We fetch the location
of the current (gdb) process and use this to identify signal
frames in core dumps from these releases. */
int mib[4];
struct kinfo_sigtramp kst;
size_t len;
mib[0] = CTL_KERN;
mib[1] = KERN_PROC;
mib[3] = getpid ();
len = sizeof (kst);
if (sysctl (mib, 4, &kst, &len, NULL, 0) == 0)
i386fbsd_sigtramp_start_addr = (uintptr_t) kst.ksigtramp_start;
i386fbsd_sigtramp_end_addr = (uintptr_t) kst.ksigtramp_end;