gdb/amd64obsd-nat.c

   1 /* Native-dependent code for OpenBSD/amd64.
   2
   3    Copyright (C) 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., 51 Franklin Street, Fifth Floor,
  20    Boston, MA 02110-1301, USA.  */
  21
  22 #include "defs.h"
  23 #include "gdbcore.h"
  24 #include "regcache.h"
  25 #include "target.h"
  26
  27 #include "gdb_assert.h"
  28
  29 #include "amd64-tdep.h"
  30 #include "amd64-nat.h"
  31
  32 /* Mapping between the general-purpose registers in OpenBSD/amd64
  33    `struct reg' format and GDB's register cache layout for
  34    OpenBSD/i386.
  35
  36    Note that most (if not all) OpenBSD/amd64 registers are 64-bit,
  37    while the OpenBSD/i386 registers are all 32-bit, but since we're
  38    little-endian we get away with that.  */
  39
  40 /* From <machine/reg.h>.  */
  41 static int amd64obsd32_r_reg_offset[] =
  42 {
  43   14 * 8,                       /* %eax */
  44   3 * 8,                        /* %ecx */
  45   2 * 8,                        /* %edx */
  46   13 * 8,                       /* %ebx */
  47   15 * 8,                       /* %esp */
  48   12 * 8,                       /* %ebp */
  49   1 * 8,                        /* %esi */
  50   0 * 8,                        /* %edi */
  51   16 * 8,                       /* %eip */
  52   17 * 8,                       /* %eflags */
  53   18 * 8,                       /* %cs */
  54   19 * 8,                       /* %ss */
  55   20 * 8,                       /* %ds */
  56   21 * 8,                       /* %es */
  57   22 * 8,                       /* %fs */
  58   23 * 8                        /* %gs */
  59 };
  60 \f
  61
  62 /* Support for debugging kernel virtual memory images.  */
  63
  64 #include <sys/types.h>
  65 #include <machine/frame.h>
  66 #include <machine/pcb.h>
  67
  68 #include "bsd-kvm.h"
  69
  70 static int
  71 amd64obsd_supply_pcb (struct regcache *regcache, struct pcb *pcb)
  72 {
  73   struct switchframe sf;
  74   int regnum;
  75
  76   /* The following is true for OpenBSD 3.5:
  77
  78      The pcb contains the stack pointer at the point of the context
  79      switch in cpu_switch().  At that point we have a stack frame as
  80      described by `struct switchframe', which for OpenBSD 3.5 has the
  81      following layout:
  82
  83      interrupt level
  84      %r15
  85      %r14
  86      %r13
  87      %r12
  88      %rbp
  89      %rbx
  90      return address
  91
  92      Together with %rsp in the pcb, this accounts for all callee-saved
  93      registers specified by the psABI.  From this information we
  94      reconstruct the register state as it would look when we just
  95      returned from cpu_switch().
  96
  97      For core dumps the pcb is saved by savectx().  In that case the
  98      stack frame only contains the return address, and there is no way
  99      to recover the other registers.  */
 100
 101   /* The stack pointer shouldn't be zero.  */
 102   if (pcb->pcb_rsp == 0)
 103     return 0;
 104
 105   /* Read the stack frame, and check its validity.  */
 106   read_memory (pcb->pcb_rsp, (gdb_byte *) &sf, sizeof sf);
 107   if (sf.sf_rbp == pcb->pcb_rbp)
 108     {
 109       /* Yes, we have a frame that matches cpu_switch().  */
 110       pcb->pcb_rsp += sizeof (struct switchframe);
 111       regcache_raw_supply (regcache, 12, &sf.sf_r12);
 112       regcache_raw_supply (regcache, 13, &sf.sf_r13);
 113       regcache_raw_supply (regcache, 14, &sf.sf_r14);
 114       regcache_raw_supply (regcache, 15, &sf.sf_r15);
 115       regcache_raw_supply (regcache, AMD64_RBX_REGNUM, &sf.sf_rbx);
 116       regcache_raw_supply (regcache, AMD64_RIP_REGNUM, &sf.sf_rip);
 117     }
 118   else
 119     {
 120       /* No, the pcb must have been last updated by savectx().  */
 121       pcb->pcb_rsp += 8;
 122       regcache_raw_supply (regcache, AMD64_RIP_REGNUM, &sf);
 123     }
 124
 125   regcache_raw_supply (regcache, AMD64_RSP_REGNUM, &pcb->pcb_rsp);
 126   regcache_raw_supply (regcache, AMD64_RBP_REGNUM, &pcb->pcb_rbp);
 127
 128   return 1;
 129 }
 130 \f
 131
 132 /* Provide a prototype to silence -Wmissing-prototypes.  */
 133 void _initialize_amd64obsd_nat (void);
 134
 135 void
 136 _initialize_amd64obsd_nat (void)
 137 {
 138   amd64_native_gregset32_reg_offset = amd64obsd32_r_reg_offset;
 139   amd64_native_gregset32_num_regs = ARRAY_SIZE (amd64obsd32_r_reg_offset);
 140   amd64_native_gregset64_reg_offset = amd64obsd_r_reg_offset;
 141
 142   /* We've got nothing to add to the common *BSD/amd64 target.  */
 143   add_target (amd64bsd_target ());
 144
 145   /* Support debugging kernel virtual memory images.  */
 146   bsd_kvm_add_target (amd64obsd_supply_pcb);
 147 }