Fix infinite recursion in amd64fbsd_sigcontext_addr

[deliverable/binutils-gdb.git] / gdb / amd64fbsd-nat.c

/* Native-dependent code for FreeBSD/amd64.

   Copyright (C) 2003-2015 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 "defs.h"
#include "inferior.h"
#include "regcache.h"
#include "target.h"

#include <signal.h>
#include <sys/types.h>
#include <sys/ptrace.h>
#include <sys/sysctl.h>
#include <machine/reg.h>

#include "fbsd-nat.h"
#include "amd64-tdep.h"
#include "amd64-nat.h"
#include "amd64bsd-nat.h"
#include "x86-nat.h"
\f

/* Offset in `struct reg' where MEMBER is stored.  */
#define REG_OFFSET(member) offsetof (struct reg, member)

/* At amd64fbsd64_r_reg_offset[REGNUM] you'll find the offset in
   `struct reg' location where the GDB register REGNUM is stored.
   Unsupported registers are marked with `-1'.  */
static int amd64fbsd64_r_reg_offset[] =
{
  REG_OFFSET (r_rax),
  REG_OFFSET (r_rbx),
  REG_OFFSET (r_rcx),
  REG_OFFSET (r_rdx),
  REG_OFFSET (r_rsi),
  REG_OFFSET (r_rdi),
  REG_OFFSET (r_rbp),
  REG_OFFSET (r_rsp),
  REG_OFFSET (r_r8),
  REG_OFFSET (r_r9),
  REG_OFFSET (r_r10),
  REG_OFFSET (r_r11),
  REG_OFFSET (r_r12),
  REG_OFFSET (r_r13),
  REG_OFFSET (r_r14),
  REG_OFFSET (r_r15),
  REG_OFFSET (r_rip),
  REG_OFFSET (r_rflags),
  REG_OFFSET (r_cs),
  REG_OFFSET (r_ss),
  -1,
  -1,
  -1,
  -1
};
\f

/* Mapping between the general-purpose registers in FreeBSD/amd64
   `struct reg' format and GDB's register cache layout for
   FreeBSD/i386.

   Note that most FreeBSD/amd64 registers are 64-bit, while the
   FreeBSD/i386 registers are all 32-bit, but since we're
   little-endian we get away with that.  */

/* From <machine/reg.h>.  */
static int amd64fbsd32_r_reg_offset[I386_NUM_GREGS] =
{
  14 * 8, 13 * 8,		/* %eax, %ecx */
  12 * 8, 11 * 8,		/* %edx, %ebx */
  20 * 8, 10 * 8,		/* %esp, %ebp */
  9 * 8, 8 * 8,			/* %esi, %edi */
  17 * 8, 19 * 8,		/* %eip, %eflags */
  18 * 8, 21 * 8,		/* %cs, %ss */
  -1, -1, -1, -1		/* %ds, %es, %fs, %gs */
};
\f

/* Support for debugging kernel virtual memory images.  */

#include <machine/pcb.h>
#include <osreldate.h>

#include "bsd-kvm.h"

static int
amd64fbsd_supply_pcb (struct regcache *regcache, struct pcb *pcb)
{
  /* The following is true for FreeBSD 5.2:

     The pcb contains %rip, %rbx, %rsp, %rbp, %r12, %r13, %r14, %r15,
     %ds, %es, %fs 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 like when we just returned from cpu_switch().  */

  /* The stack pointer shouldn't be zero.  */
  if (pcb->pcb_rsp == 0)
    return 0;

  pcb->pcb_rsp += 8;
  regcache_raw_supply (regcache, AMD64_RIP_REGNUM, &pcb->pcb_rip);
  regcache_raw_supply (regcache, AMD64_RBX_REGNUM, &pcb->pcb_rbx);
  regcache_raw_supply (regcache, AMD64_RSP_REGNUM, &pcb->pcb_rsp);
  regcache_raw_supply (regcache, AMD64_RBP_REGNUM, &pcb->pcb_rbp);
  regcache_raw_supply (regcache, 12, &pcb->pcb_r12);
  regcache_raw_supply (regcache, 13, &pcb->pcb_r13);
  regcache_raw_supply (regcache, 14, &pcb->pcb_r14);
  regcache_raw_supply (regcache, 15, &pcb->pcb_r15);
#if (__FreeBSD_version < 800075) && (__FreeBSD_kernel_version < 800075)
  /* struct pcb provides the pcb_ds/pcb_es/pcb_fs/pcb_gs fields only
     up until __FreeBSD_version 800074: The removal of these fields
     occurred on 2009-04-01 while the __FreeBSD_version number was
     bumped to 800075 on 2009-04-06.  So 800075 is the closest version
     number where we should not try to access these fields.  */
  regcache_raw_supply (regcache, AMD64_DS_REGNUM, &pcb->pcb_ds);
  regcache_raw_supply (regcache, AMD64_ES_REGNUM, &pcb->pcb_es);
  regcache_raw_supply (regcache, AMD64_FS_REGNUM, &pcb->pcb_fs);
  regcache_raw_supply (regcache, AMD64_GS_REGNUM, &pcb->pcb_gs);
#endif

  return 1;
}
\f

static void (*super_mourn_inferior) (struct target_ops *ops);

static void
amd64fbsd_mourn_inferior (struct target_ops *ops)
{
#ifdef HAVE_PT_GETDBREGS
  x86_cleanup_dregs ();
#endif
  super_mourn_inferior (ops);
}

/* Provide a prototype to silence -Wmissing-prototypes.  */
void _initialize_amd64fbsd_nat (void);

void
_initialize_amd64fbsd_nat (void)
{
  struct target_ops *t;
  int offset;

  amd64_native_gregset32_reg_offset = amd64fbsd32_r_reg_offset;
  amd64_native_gregset64_reg_offset = amd64fbsd64_r_reg_offset;

  /* Add some extra features to the common *BSD/i386 target.  */
  t = amd64bsd_target ();

#ifdef HAVE_PT_GETDBREGS

  x86_use_watchpoints (t);

  x86_dr_low.set_control = amd64bsd_dr_set_control;
  x86_dr_low.set_addr = amd64bsd_dr_set_addr;
  x86_dr_low.get_addr = amd64bsd_dr_get_addr;
  x86_dr_low.get_status = amd64bsd_dr_get_status;
  x86_dr_low.get_control = amd64bsd_dr_get_control;
  x86_set_debug_register_length (8);

#endif /* HAVE_PT_GETDBREGS */

  super_mourn_inferior = t->to_mourn_inferior;
  t->to_mourn_inferior = amd64fbsd_mourn_inferior;

  t->to_pid_to_exec_file = fbsd_pid_to_exec_file;
  t->to_find_memory_regions = fbsd_find_memory_regions;
  add_target (t);

  /* Support debugging kernel virtual memory images.  */
  bsd_kvm_add_target (amd64fbsd_supply_pcb);

  /* To support the recognition of signal handlers, i386bsd-tdep.c
     hardcodes some constants.  Inclusion of this file means that we
     are compiling a native debugger, which means that we can use the
     system header files and sysctl(3) to get at the relevant
     information.  */

#define SC_REG_OFFSET amd64fbsd_sc_reg_offset

  /* We only check the program counter, stack pointer and frame
     pointer since these members of `struct sigcontext' are essential
     for providing backtraces.  */

#define SC_RIP_OFFSET SC_REG_OFFSET[AMD64_RIP_REGNUM]
#define SC_RSP_OFFSET SC_REG_OFFSET[AMD64_RSP_REGNUM]
#define SC_RBP_OFFSET SC_REG_OFFSET[AMD64_RBP_REGNUM]

  /* Override the default value for the offset of the program counter
     in the sigcontext structure.  */
  offset = offsetof (struct sigcontext, sc_rip);

  if (SC_RIP_OFFSET != offset)
    {
      warning (_("\
offsetof (struct sigcontext, sc_rip) yields %d instead of %d.\n\
Please report this to <bug-gdb@gnu.org>."),
	       offset, SC_RIP_OFFSET);
    }

  SC_RIP_OFFSET = offset;

  /* Likewise for the stack pointer.  */
  offset = offsetof (struct sigcontext, sc_rsp);

  if (SC_RSP_OFFSET != offset)
    {
      warning (_("\
offsetof (struct sigcontext, sc_rsp) yields %d instead of %d.\n\
Please report this to <bug-gdb@gnu.org>."),
	       offset, SC_RSP_OFFSET);
    }

  SC_RSP_OFFSET = offset;

  /* And the frame pointer.  */
  offset = offsetof (struct sigcontext, sc_rbp);

  if (SC_RBP_OFFSET != offset)
    {
      warning (_("\
offsetof (struct sigcontext, sc_rbp) yields %d instead of %d.\n\
Please report this to <bug-gdb@gnu.org>."),
	       offset, SC_RBP_OFFSET);
    }

  SC_RBP_OFFSET = offset;

  /* FreeBSD provides a kern.ps_strings sysctl that we can use to
     locate the sigtramp.  That way we can still recognize a sigtramp
     if its location is changed in a new kernel.  Of course this is
     still based on the assumption that the sigtramp is placed
     directly under the location where the program arguments and
     environment can be found.  */
  {
    int mib[2];
    long ps_strings;
    size_t len;

    mib[0] = CTL_KERN;
    mib[1] = KERN_PS_STRINGS;
    len = sizeof (ps_strings);
    if (sysctl (mib, 2, &ps_strings, &len, NULL, 0) == 0)
      {
	amd64fbsd_sigtramp_start_addr = ps_strings - 32;
	amd64fbsd_sigtramp_end_addr = ps_strings;
      }
  }
}