gdb/amd64fbsd-nat.c

   1 /* Native-dependent code for FreeBSD/amd64.
   2
   3    Copyright (C) 2003-2016 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 3 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, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "defs.h"
  21 #include "inferior.h"
  22 #include "regcache.h"
  23 #include "target.h"
  24
  25 #include <signal.h>
  26 #include <sys/types.h>
  27 #include <sys/ptrace.h>
  28 #include <sys/sysctl.h>
  29 #include <sys/user.h>
  30 #include <machine/reg.h>
  31
  32 #include "fbsd-nat.h"
  33 #include "amd64-tdep.h"
  34 #include "amd64-nat.h"
  35 #include "x86bsd-nat.h"
  36 #include "x86-nat.h"
  37 \f
  38
  39 /* Offset in `struct reg' where MEMBER is stored.  */
  40 #define REG_OFFSET(member) offsetof (struct reg, member)
  41
  42 /* At amd64fbsd64_r_reg_offset[REGNUM] you'll find the offset in
  43    `struct reg' location where the GDB register REGNUM is stored.
  44    Unsupported registers are marked with `-1'.  */
  45 static int amd64fbsd64_r_reg_offset[] =
  46 {
  47   REG_OFFSET (r_rax),
  48   REG_OFFSET (r_rbx),
  49   REG_OFFSET (r_rcx),
  50   REG_OFFSET (r_rdx),
  51   REG_OFFSET (r_rsi),
  52   REG_OFFSET (r_rdi),
  53   REG_OFFSET (r_rbp),
  54   REG_OFFSET (r_rsp),
  55   REG_OFFSET (r_r8),
  56   REG_OFFSET (r_r9),
  57   REG_OFFSET (r_r10),
  58   REG_OFFSET (r_r11),
  59   REG_OFFSET (r_r12),
  60   REG_OFFSET (r_r13),
  61   REG_OFFSET (r_r14),
  62   REG_OFFSET (r_r15),
  63   REG_OFFSET (r_rip),
  64   REG_OFFSET (r_rflags),
  65   REG_OFFSET (r_cs),
  66   REG_OFFSET (r_ss),
  67   -1,
  68   -1,
  69   -1,
  70   -1
  71 };
  72 \f
  73
  74 /* Mapping between the general-purpose registers in FreeBSD/amd64
  75    `struct reg' format and GDB's register cache layout for
  76    FreeBSD/i386.
  77
  78    Note that most FreeBSD/amd64 registers are 64-bit, while the
  79    FreeBSD/i386 registers are all 32-bit, but since we're
  80    little-endian we get away with that.  */
  81
  82 /* From <machine/reg.h>.  */
  83 static int amd64fbsd32_r_reg_offset[I386_NUM_GREGS] =
  84 {
  85   14 * 8, 13 * 8,               /* %eax, %ecx */
  86   12 * 8, 11 * 8,               /* %edx, %ebx */
  87   20 * 8, 10 * 8,               /* %esp, %ebp */
  88   9 * 8, 8 * 8,                 /* %esi, %edi */
  89   17 * 8, 19 * 8,               /* %eip, %eflags */
  90   18 * 8, 21 * 8,               /* %cs, %ss */
  91   -1, -1, -1, -1                /* %ds, %es, %fs, %gs */
  92 };
  93 \f
  94
  95 /* Support for debugging kernel virtual memory images.  */
  96
  97 #include <machine/pcb.h>
  98 #include <osreldate.h>
  99
 100 #include "bsd-kvm.h"
 101
 102 static int
 103 amd64fbsd_supply_pcb (struct regcache *regcache, struct pcb *pcb)
 104 {
 105   /* The following is true for FreeBSD 5.2:
 106
 107      The pcb contains %rip, %rbx, %rsp, %rbp, %r12, %r13, %r14, %r15,
 108      %ds, %es, %fs and %gs.  This accounts for all callee-saved
 109      registers specified by the psABI and then some.  Here %esp
 110      contains the stack pointer at the point just after the call to
 111      cpu_switch().  From this information we reconstruct the register
 112      state as it would like when we just returned from cpu_switch().  */
 113
 114   /* The stack pointer shouldn't be zero.  */
 115   if (pcb->pcb_rsp == 0)
 116     return 0;
 117
 118   pcb->pcb_rsp += 8;
 119   regcache_raw_supply (regcache, AMD64_RIP_REGNUM, &pcb->pcb_rip);
 120   regcache_raw_supply (regcache, AMD64_RBX_REGNUM, &pcb->pcb_rbx);
 121   regcache_raw_supply (regcache, AMD64_RSP_REGNUM, &pcb->pcb_rsp);
 122   regcache_raw_supply (regcache, AMD64_RBP_REGNUM, &pcb->pcb_rbp);
 123   regcache_raw_supply (regcache, 12, &pcb->pcb_r12);
 124   regcache_raw_supply (regcache, 13, &pcb->pcb_r13);
 125   regcache_raw_supply (regcache, 14, &pcb->pcb_r14);
 126   regcache_raw_supply (regcache, 15, &pcb->pcb_r15);
 127 #if (__FreeBSD_version < 800075) && (__FreeBSD_kernel_version < 800075)
 128   /* struct pcb provides the pcb_ds/pcb_es/pcb_fs/pcb_gs fields only
 129      up until __FreeBSD_version 800074: The removal of these fields
 130      occurred on 2009-04-01 while the __FreeBSD_version number was
 131      bumped to 800075 on 2009-04-06.  So 800075 is the closest version
 132      number where we should not try to access these fields.  */
 133   regcache_raw_supply (regcache, AMD64_DS_REGNUM, &pcb->pcb_ds);
 134   regcache_raw_supply (regcache, AMD64_ES_REGNUM, &pcb->pcb_es);
 135   regcache_raw_supply (regcache, AMD64_FS_REGNUM, &pcb->pcb_fs);
 136   regcache_raw_supply (regcache, AMD64_GS_REGNUM, &pcb->pcb_gs);
 137 #endif
 138
 139   return 1;
 140 }
 141 \f
 142
 143 /* Implement the to_read_description method.  */
 144
 145 static const struct target_desc *
 146 amd64fbsd_read_description (struct target_ops *ops)
 147 {
 148 #ifdef PT_GETXSTATE_INFO
 149   static int xsave_probed;
 150   static uint64_t xcr0;
 151 #endif
 152   struct reg regs;
 153   int is64;
 154
 155   if (ptrace (PT_GETREGS, ptid_get_pid (inferior_ptid),
 156               (PTRACE_TYPE_ARG3) &regs, 0) == -1)
 157     perror_with_name (_("Couldn't get registers"));
 158   is64 = (regs.r_cs == GSEL (GUCODE_SEL, SEL_UPL));
 159 #ifdef PT_GETXSTATE_INFO
 160   if (!xsave_probed)
 161     {
 162       struct ptrace_xstate_info info;
 163
 164       if (ptrace (PT_GETXSTATE_INFO, ptid_get_pid (inferior_ptid),
 165                   (PTRACE_TYPE_ARG3) &info, sizeof (info)) == 0)
 166         {
 167           x86bsd_xsave_len = info.xsave_len;
 168           xcr0 = info.xsave_mask;
 169         }
 170       xsave_probed = 1;
 171     }
 172
 173   if (x86bsd_xsave_len != 0)
 174     {
 175       if (is64)
 176         return amd64_target_description (xcr0);
 177       else
 178         return i386_target_description (xcr0);
 179     }
 180 #endif
 181   if (is64)
 182     return tdesc_amd64;
 183   else
 184     return tdesc_i386;
 185 }
 186
 187 /* Provide a prototype to silence -Wmissing-prototypes.  */
 188 void _initialize_amd64fbsd_nat (void);
 189
 190 void
 191 _initialize_amd64fbsd_nat (void)
 192 {
 193   struct target_ops *t;
 194   int offset;
 195
 196   amd64_native_gregset32_reg_offset = amd64fbsd32_r_reg_offset;
 197   amd64_native_gregset64_reg_offset = amd64fbsd64_r_reg_offset;
 198
 199   /* Add some extra features to the common *BSD/i386 target.  */
 200   t = amd64bsd_target ();
 201   t->to_read_description = amd64fbsd_read_description;
 202
 203   fbsd_nat_add_target (t);
 204
 205   /* Support debugging kernel virtual memory images.  */
 206   bsd_kvm_add_target (amd64fbsd_supply_pcb);
 207
 208   /* To support the recognition of signal handlers, i386bsd-tdep.c
 209      hardcodes some constants.  Inclusion of this file means that we
 210      are compiling a native debugger, which means that we can use the
 211      system header files and sysctl(3) to get at the relevant
 212      information.  */
 213
 214 #define SC_REG_OFFSET amd64fbsd_sc_reg_offset
 215
 216   /* We only check the program counter, stack pointer and frame
 217      pointer since these members of `struct sigcontext' are essential
 218      for providing backtraces.  */
 219
 220 #define SC_RIP_OFFSET SC_REG_OFFSET[AMD64_RIP_REGNUM]
 221 #define SC_RSP_OFFSET SC_REG_OFFSET[AMD64_RSP_REGNUM]
 222 #define SC_RBP_OFFSET SC_REG_OFFSET[AMD64_RBP_REGNUM]
 223
 224   /* Override the default value for the offset of the program counter
 225      in the sigcontext structure.  */
 226   offset = offsetof (struct sigcontext, sc_rip);
 227
 228   if (SC_RIP_OFFSET != offset)
 229     {
 230       warning (_("\
 231 offsetof (struct sigcontext, sc_rip) yields %d instead of %d.\n\
 232 Please report this to <bug-gdb@gnu.org>."),
 233                offset, SC_RIP_OFFSET);
 234     }
 235
 236   SC_RIP_OFFSET = offset;
 237
 238   /* Likewise for the stack pointer.  */
 239   offset = offsetof (struct sigcontext, sc_rsp);
 240
 241   if (SC_RSP_OFFSET != offset)
 242     {
 243       warning (_("\
 244 offsetof (struct sigcontext, sc_rsp) yields %d instead of %d.\n\
 245 Please report this to <bug-gdb@gnu.org>."),
 246                offset, SC_RSP_OFFSET);
 247     }
 248
 249   SC_RSP_OFFSET = offset;
 250
 251   /* And the frame pointer.  */
 252   offset = offsetof (struct sigcontext, sc_rbp);
 253
 254   if (SC_RBP_OFFSET != offset)
 255     {
 256       warning (_("\
 257 offsetof (struct sigcontext, sc_rbp) yields %d instead of %d.\n\
 258 Please report this to <bug-gdb@gnu.org>."),
 259                offset, SC_RBP_OFFSET);
 260     }
 261
 262   SC_RBP_OFFSET = offset;
 263
 264 #ifdef KERN_PROC_SIGTRAMP
 265   /* Normally signal frames are detected via amd64fbsd_sigtramp_p.
 266      However, FreeBSD 9.2 through 10.1 do not include the page holding
 267      the signal code in core dumps.  These releases do provide a
 268      kern.proc.sigtramp.<pid> sysctl that returns the location of the
 269      signal trampoline for a running process.  We fetch the location
 270      of the current (gdb) process and use this to identify signal
 271      frames in core dumps from these releases.  Note that this only
 272      works for core dumps of 64-bit (FreeBSD/amd64) processes and does
 273      not handle core dumps of 32-bit (FreeBSD/i386) processes.  */
 274   {
 275     int mib[4];
 276     struct kinfo_sigtramp kst;
 277     size_t len;
 278
 279     mib[0] = CTL_KERN;
 280     mib[1] = KERN_PROC;
 281     mib[2] = KERN_PROC_SIGTRAMP;
 282     mib[3] = getpid ();
 283     len = sizeof (kst);
 284     if (sysctl (mib, 4, &kst, &len, NULL, 0) == 0)
 285       {
 286         amd64fbsd_sigtramp_start_addr = (uintptr_t) kst.ksigtramp_start;
 287         amd64fbsd_sigtramp_end_addr = (uintptr_t) kst.ksigtramp_end;
 288       }
 289   }
 290 #endif
 291 }