contrib/gdb-6.2.1/gdb/i386fbsd-nat.c

   1 /* Native-dependent code for FreeBSD/i386.
   2
   3    Copyright 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 59 Temple Place - Suite 330,
  20    Boston, MA 02111-1307, USA.  */
  21
  22 #include "defs.h"
  23 #include "inferior.h"
  24 #include "regcache.h"
  25
  26 #include <sys/types.h>
  27 #include <sys/ptrace.h>
  28 #include <sys/sysctl.h>
  29
  30 #include "i386-tdep.h"
  31
  32 /* Resume execution of the inferior process.
  33    If STEP is nonzero, single-step it.
  34    If SIGNAL is nonzero, give it that signal.  */
  35
  36 void
  37 child_resume (ptid_t ptid, int step, enum target_signal signal)
  38 {
  39   pid_t pid = ptid_get_pid (ptid);
  40   int request = PT_STEP;
  41
  42   if (pid == -1)
  43     /* Resume all threads.  This only gets used in the non-threaded
  44        case, where "resume all threads" and "resume inferior_ptid" are
  45        the same.  */
  46     pid = ptid_get_pid (inferior_ptid);
  47
  48   if (!step)
  49     {
  50       ULONGEST eflags;
  51
  52       /* Workaround for a bug in FreeBSD.  Make sure that the trace
  53          flag is off when doing a continue.  There is a code path
  54          through the kernel which leaves the flag set when it should
  55          have been cleared.  If a process has a signal pending (such
  56          as SIGALRM) and we do a PT_STEP, the process never really has
  57          a chance to run because the kernel needs to notify the
  58          debugger that a signal is being sent.  Therefore, the process
  59          never goes through the kernel's trap() function which would
  60          normally clear it.  */
  61
  62       regcache_cooked_read_unsigned (current_regcache, I386_EFLAGS_REGNUM,
  63                                      &eflags);
  64       if (eflags & 0x0100)
  65         regcache_cooked_write_unsigned (current_regcache, I386_EFLAGS_REGNUM,
  66                                         eflags & ~0x0100);
  67
  68       request = PT_CONTINUE;
  69     }
  70
  71   /* An addres of (caddr_t) 1 tells ptrace to continue from where it
  72      was.  (If GDB wanted it to start some other way, we have already
  73      written a new PC value to the child.)  */
  74   if (ptrace (request, pid, (caddr_t) 1,
  75               target_signal_to_host (signal)) == -1)
  76     perror_with_name ("ptrace");
  77 }
  78 \f
  79
  80 /* Support for debugging kernel virtual memory images.  */
  81
  82 #include <sys/types.h>
  83 #include <machine/pcb.h>
  84
  85 #include "bsd-kvm.h"
  86
  87 static int
  88 i386fbsd_supply_pcb (struct regcache *regcache, struct pcb *pcb)
  89 {
  90   /* The following is true for FreeBSD 4.7:
  91
  92      The pcb contains %eip, %ebx, %esp, %ebp, %esi, %edi and %gs.
  93      This accounts for all callee-saved registers specified by the
  94      psABI and then some.  Here %esp contains the stack pointer at the
  95      point just after the call to cpu_switch().  From this information
  96      we reconstruct the register state as it would look when we just
  97      returned from cpu_switch().  */
  98
  99   /* The stack pointer shouldn't be zero.  */
 100   if (pcb->pcb_esp == 0)
 101     return 0;
 102
 103   pcb->pcb_esp += 4;
 104   regcache_raw_supply (regcache, I386_EDI_REGNUM, &pcb->pcb_edi);
 105   regcache_raw_supply (regcache, I386_ESI_REGNUM, &pcb->pcb_esi);
 106   regcache_raw_supply (regcache, I386_EBP_REGNUM, &pcb->pcb_ebp);
 107   regcache_raw_supply (regcache, I386_ESP_REGNUM, &pcb->pcb_esp);
 108   regcache_raw_supply (regcache, I386_EBX_REGNUM, &pcb->pcb_ebx);
 109   regcache_raw_supply (regcache, I386_EIP_REGNUM, &pcb->pcb_eip);
 110
 111   return 1;
 112 }
 113 \f
 114
 115 /* Prevent warning from -Wmissing-prototypes.  */
 116 void _initialize_i386fbsd_nat (void);
 117
 118 void
 119 _initialize_i386fbsd_nat (void)
 120 {
 121   /* FreeBSD provides a kern.ps_strings sysctl that we can use to
 122      locate the sigtramp.  That way we can still recognize a sigtramp
 123      if its location is changed in a new kernel.  Of course this is
 124      still based on the assumption that the sigtramp is placed
 125      directly under the location where the program arguments and
 126      environment can be found.  */
 127 #ifdef KERN_PS_STRINGS
 128   {
 129     int mib[2];
 130     int ps_strings;
 131     size_t len;
 132
 133     mib[0] = CTL_KERN;
 134     mib[1] = KERN_PS_STRINGS;
 135     len = sizeof (ps_strings);
 136     if (sysctl (mib, 2, &ps_strings, &len, NULL, 0) == 0)
 137       {
 138         i386fbsd_sigtramp_start_addr = ps_strings - 128;
 139         i386fbsd_sigtramp_end_addr = ps_strings;
 140       }
 141   }
 142 #endif
 143 }