gdb/amd64-fbsd-nat.c

   1 /* Native-dependent code for FreeBSD/amd64.
   2
   3    Copyright (C) 2003-2017 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 "x86-bsd-nat.h"
  36 #include "x86-nat.h"
  37 #include "x86-xstate.h"
  38 \f
  39
  40 /* Offset in `struct reg' where MEMBER is stored.  */
  41 #define REG_OFFSET(member) offsetof (struct reg, member)
  42
  43 /* At amd64fbsd64_r_reg_offset[REGNUM] you'll find the offset in
  44    `struct reg' location where the GDB register REGNUM is stored.
  45    Unsupported registers are marked with `-1'.  */
  46 static int amd64fbsd64_r_reg_offset[] =
  47 {
  48   REG_OFFSET (r_rax),
  49   REG_OFFSET (r_rbx),
  50   REG_OFFSET (r_rcx),
  51   REG_OFFSET (r_rdx),
  52   REG_OFFSET (r_rsi),
  53   REG_OFFSET (r_rdi),
  54   REG_OFFSET (r_rbp),
  55   REG_OFFSET (r_rsp),
  56   REG_OFFSET (r_r8),
  57   REG_OFFSET (r_r9),
  58   REG_OFFSET (r_r10),
  59   REG_OFFSET (r_r11),
  60   REG_OFFSET (r_r12),
  61   REG_OFFSET (r_r13),
  62   REG_OFFSET (r_r14),
  63   REG_OFFSET (r_r15),
  64   REG_OFFSET (r_rip),
  65   REG_OFFSET (r_rflags),
  66   REG_OFFSET (r_cs),
  67   REG_OFFSET (r_ss),
  68   -1,
  69   -1,
  70   -1,
  71   -1
  72 };
  73 \f
  74
  75 /* Mapping between the general-purpose registers in FreeBSD/amd64
  76    `struct reg' format and GDB's register cache layout for
  77    FreeBSD/i386.
  78
  79    Note that most FreeBSD/amd64 registers are 64-bit, while the
  80    FreeBSD/i386 registers are all 32-bit, but since we're
  81    little-endian we get away with that.  */
  82
  83 /* From <machine/reg.h>.  */
  84 static int amd64fbsd32_r_reg_offset[I386_NUM_GREGS] =
  85 {
  86   14 * 8, 13 * 8,               /* %eax, %ecx */
  87   12 * 8, 11 * 8,               /* %edx, %ebx */
  88   20 * 8, 10 * 8,               /* %esp, %ebp */
  89   9 * 8, 8 * 8,                 /* %esi, %edi */
  90   17 * 8, 19 * 8,               /* %eip, %eflags */
  91   18 * 8, 21 * 8,               /* %cs, %ss */
  92   -1, -1, -1, -1                /* %ds, %es, %fs, %gs */
  93 };
  94 \f
  95
  96 /* Support for debugging kernel virtual memory images.  */
  97
  98 #include <machine/pcb.h>
  99 #include <osreldate.h>
 100
 101 #include "bsd-kvm.h"
 102
 103 static int
 104 amd64fbsd_supply_pcb (struct regcache *regcache, struct pcb *pcb)
 105 {
 106   /* The following is true for FreeBSD 5.2:
 107
 108      The pcb contains %rip, %rbx, %rsp, %rbp, %r12, %r13, %r14, %r15,
 109      %ds, %es, %fs and %gs.  This accounts for all callee-saved
 110      registers specified by the psABI and then some.  Here %esp
 111      contains the stack pointer at the point just after the call to
 112      cpu_switch().  From this information we reconstruct the register
 113      state as it would like when we just returned from cpu_switch().  */
 114
 115   /* The stack pointer shouldn't be zero.  */
 116   if (pcb->pcb_rsp == 0)
 117     return 0;
 118
 119   pcb->pcb_rsp += 8;
 120   regcache_raw_supply (regcache, AMD64_RIP_REGNUM, &pcb->pcb_rip);
 121   regcache_raw_supply (regcache, AMD64_RBX_REGNUM, &pcb->pcb_rbx);
 122   regcache_raw_supply (regcache, AMD64_RSP_REGNUM, &pcb->pcb_rsp);
 123   regcache_raw_supply (regcache, AMD64_RBP_REGNUM, &pcb->pcb_rbp);
 124   regcache_raw_supply (regcache, 12, &pcb->pcb_r12);
 125   regcache_raw_supply (regcache, 13, &pcb->pcb_r13);
 126   regcache_raw_supply (regcache, 14, &pcb->pcb_r14);
 127   regcache_raw_supply (regcache, 15, &pcb->pcb_r15);
 128 #if (__FreeBSD_version < 800075) && (__FreeBSD_kernel_version < 800075)
 129   /* struct pcb provides the pcb_ds/pcb_es/pcb_fs/pcb_gs fields only
 130      up until __FreeBSD_version 800074: The removal of these fields
 131      occurred on 2009-04-01 while the __FreeBSD_version number was
 132      bumped to 800075 on 2009-04-06.  So 800075 is the closest version
 133      number where we should not try to access these fields.  */
 134   regcache_raw_supply (regcache, AMD64_DS_REGNUM, &pcb->pcb_ds);
 135   regcache_raw_supply (regcache, AMD64_ES_REGNUM, &pcb->pcb_es);
 136   regcache_raw_supply (regcache, AMD64_FS_REGNUM, &pcb->pcb_fs);
 137   regcache_raw_supply (regcache, AMD64_GS_REGNUM, &pcb->pcb_gs);
 138 #endif
 139
 140   return 1;
 141 }
 142 \f
 143
 144 /* Implement the to_read_description method.  */
 145
 146 static const struct target_desc *
 147 amd64fbsd_read_description (struct target_ops *ops)
 148 {
 149 #ifdef PT_GETXSTATE_INFO
 150   static int xsave_probed;
 151   static uint64_t xcr0;
 152 #endif
 153   struct reg regs;
 154   int is64;
 155
 156   if (ptrace (PT_GETREGS, ptid_get_pid (inferior_ptid),
 157               (PTRACE_TYPE_ARG3) &regs, 0) == -1)
 158     perror_with_name (_("Couldn't get registers"));
 159   is64 = (regs.r_cs == GSEL (GUCODE_SEL, SEL_UPL));
 160 #ifdef PT_GETXSTATE_INFO
 161   if (!xsave_probed)
 162     {
 163       struct ptrace_xstate_info info;
 164
 165       if (ptrace (PT_GETXSTATE_INFO, ptid_get_pid (inferior_ptid),
 166                   (PTRACE_TYPE_ARG3) &info, sizeof (info)) == 0)
 167         {
 168           x86bsd_xsave_len = info.xsave_len;
 169           xcr0 = info.xsave_mask;
 170         }
 171       xsave_probed = 1;
 172     }
 173
 174   if (x86bsd_xsave_len != 0)
 175     {
 176       if (is64)
 177         return amd64_target_description (xcr0);
 178       else
 179         return i386_target_description (xcr0);
 180     }
 181 #endif
 182   if (is64)
 183     return amd64_target_description (X86_XSTATE_SSE_MASK);
 184   else
 185     return i386_target_description (X86_XSTATE_SSE_MASK);
 186 }
 187
 188 /* Provide a prototype to silence -Wmissing-prototypes.  */
 189 void _initialize_amd64fbsd_nat (void);
 190
 191 void
 192 _initialize_amd64fbsd_nat (void)
 193 {
 194   struct target_ops *t;
 195   int offset;
 196
 197   amd64_native_gregset32_reg_offset = amd64fbsd32_r_reg_offset;
 198   amd64_native_gregset64_reg_offset = amd64fbsd64_r_reg_offset;
 199
 200   /* Add some extra features to the common *BSD/i386 target.  */
 201   t = amd64bsd_target ();
 202   t->to_read_description = amd64fbsd_read_description;
 203
 204   fbsd_nat_add_target (t);
 205
 206   /* Support debugging kernel virtual memory images.  */
 207   bsd_kvm_add_target (amd64fbsd_supply_pcb);
 208
 209   /* To support the recognition of signal handlers, i386-bsd-tdep.c
 210      hardcodes some constants.  Inclusion of this file means that we
 211      are compiling a native debugger, which means that we can use the
 212      system header files and sysctl(3) to get at the relevant
 213      information.  */
 214
 215 #define SC_REG_OFFSET amd64fbsd_sc_reg_offset
 216
 217   /* We only check the program counter, stack pointer and frame
 218      pointer since these members of `struct sigcontext' are essential
 219      for providing backtraces.  */
 220
 221 #define SC_RIP_OFFSET SC_REG_OFFSET[AMD64_RIP_REGNUM]
 222 #define SC_RSP_OFFSET SC_REG_OFFSET[AMD64_RSP_REGNUM]
 223 #define SC_RBP_OFFSET SC_REG_OFFSET[AMD64_RBP_REGNUM]
 224
 225   /* Override the default value for the offset of the program counter
 226      in the sigcontext structure.  */
 227   offset = offsetof (struct sigcontext, sc_rip);
 228
 229   if (SC_RIP_OFFSET != offset)
 230     {
 231       warning (_("\
 232 offsetof (struct sigcontext, sc_rip) yields %d instead of %d.\n\
 233 Please report this to <bug-gdb@gnu.org>."),
 234                offset, SC_RIP_OFFSET);
 235     }
 236
 237   SC_RIP_OFFSET = offset;
 238
 239   /* Likewise for the stack pointer.  */
 240   offset = offsetof (struct sigcontext, sc_rsp);
 241
 242   if (SC_RSP_OFFSET != offset)
 243     {
 244       warning (_("\
 245 offsetof (struct sigcontext, sc_rsp) yields %d instead of %d.\n\
 246 Please report this to <bug-gdb@gnu.org>."),
 247                offset, SC_RSP_OFFSET);
 248     }
 249
 250   SC_RSP_OFFSET = offset;
 251
 252   /* And the frame pointer.  */
 253   offset = offsetof (struct sigcontext, sc_rbp);
 254
 255   if (SC_RBP_OFFSET != offset)
 256     {
 257       warning (_("\
 258 offsetof (struct sigcontext, sc_rbp) yields %d instead of %d.\n\
 259 Please report this to <bug-gdb@gnu.org>."),
 260                offset, SC_RBP_OFFSET);
 261     }
 262
 263   SC_RBP_OFFSET = offset;
 264
 265 #ifdef KERN_PROC_SIGTRAMP
 266   /* Normally signal frames are detected via amd64fbsd_sigtramp_p.
 267      However, FreeBSD 9.2 through 10.1 do not include the page holding
 268      the signal code in core dumps.  These releases do provide a
 269      kern.proc.sigtramp.<pid> sysctl that returns the location of the
 270      signal trampoline for a running process.  We fetch the location
 271      of the current (gdb) process and use this to identify signal
 272      frames in core dumps from these releases.  Note that this only
 273      works for core dumps of 64-bit (FreeBSD/amd64) processes and does
 274      not handle core dumps of 32-bit (FreeBSD/i386) processes.  */
 275   {
 276     int mib[4];
 277     struct kinfo_sigtramp kst;
 278     size_t len;
 279
 280     mib[0] = CTL_KERN;
 281     mib[1] = KERN_PROC;
 282     mib[2] = KERN_PROC_SIGTRAMP;
 283     mib[3] = getpid ();
 284     len = sizeof (kst);
 285     if (sysctl (mib, 4, &kst, &len, NULL, 0) == 0)
 286       {
 287         amd64fbsd_sigtramp_start_addr = (uintptr_t) kst.ksigtramp_start;
 288         amd64fbsd_sigtramp_end_addr = (uintptr_t) kst.ksigtramp_end;
 289       }
 290   }
 291 #endif
 292 }