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/* Native-dependent code for FreeBSD/i386.

   Copyright (C) 2001, 2002, 2003, 2004, 2007, 2008

   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 <sys/types.h>

#include <sys/ptrace.h>

#include <sys/sysctl.h>

#include "fbsd-nat.h"

#include "i386-tdep.h"

#include "i386bsd-nat.h"

/* Resume execution of the inferior process.  If STEP is nonzero,

   single-step it.  If SIGNAL is nonzero, give it that signal.  */

static void

i386fbsd_resume (ptid_t ptid, int step, enum target_signal signal)

{

  pid_t pid = ptid_get_pid (ptid);

  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 = ptid_get_pid (inferior_ptid);

  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,

                                     &eflags);

      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,

              target_signal_to_host (signal)) == -1)

    perror_with_name (("ptrace"));

}

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

#include <sys/types.h>

#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 (regcache, I386_EDI_REGNUM, &pcb->pcb_edi);

  regcache_raw_supply (regcache, I386_ESI_REGNUM, &pcb->pcb_esi);

  regcache_raw_supply (regcache, I386_EBP_REGNUM, &pcb->pcb_ebp);

  regcache_raw_supply (regcache, I386_ESP_REGNUM, &pcb->pcb_esp);

  regcache_raw_supply (regcache, I386_EBX_REGNUM, &pcb->pcb_ebx);

  regcache_raw_supply (regcache, I386_EIP_REGNUM, &pcb->pcb_eip);

  regcache_raw_supply (regcache, I386_GS_REGNUM, &pcb->pcb_gs);

  return 1;

}

/* Prevent warning from -Wmissing-prototypes.  */

void _initialize_i386fbsd_nat (void);

void

_initialize_i386fbsd_nat (void)

{

  struct target_ops *t;

  /* Add some extra features to the common *BSD/i386 target.  */

  t = i386bsd_target ();

  t->to_resume = i386fbsd_resume;

  t->to_pid_to_exec_file = fbsd_pid_to_exec_file;

  t->to_find_memory_regions = fbsd_find_memory_regions;

  t->to_make_corefile_notes = fbsd_make_corefile_notes;

  add_target (t);

  /* Support debugging kernel virtual memory images.  */

  bsd_kvm_add_target (i386fbsd_supply_pcb);

  /* 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.  */

#ifdef KERN_PS_STRINGS

  {

    int mib[2];

    u_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)

      {

        i386fbsd_sigtramp_start_addr = ps_strings - 128;

        i386fbsd_sigtramp_end_addr = ps_strings;

      }

  }

#endif

}