gdbserver/linux-amd64-ipa.cc

   1 /* GNU/Linux/x86-64 specific low level interface, for the in-process
   2    agent library for GDB.
   3
   4    Copyright (C) 2010-2021 Free Software Foundation, Inc.
   5
   6    This file is part of GDB.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #include "server.h"
  22 #include <sys/mman.h>
  23 #include "tracepoint.h"
  24 #include "linux-x86-tdesc.h"
  25 #include "gdbsupport/x86-xstate.h"
  26
  27 /* Defined in auto-generated file amd64-linux.c.  */
  28 void init_registers_amd64_linux (void);
  29 extern const struct target_desc *tdesc_amd64_linux;
  30
  31 /* fast tracepoints collect registers.  */
  32
  33 #define FT_CR_RIP 0
  34 #define FT_CR_EFLAGS 1
  35 #define FT_CR_R8 2
  36 #define FT_CR_R9 3
  37 #define FT_CR_R10 4
  38 #define FT_CR_R11 5
  39 #define FT_CR_R12 6
  40 #define FT_CR_R13 7
  41 #define FT_CR_R14 8
  42 #define FT_CR_R15 9
  43 #define FT_CR_RAX 10
  44 #define FT_CR_RBX 11
  45 #define FT_CR_RCX 12
  46 #define FT_CR_RDX 13
  47 #define FT_CR_RSI 14
  48 #define FT_CR_RDI 15
  49 #define FT_CR_RBP 16
  50 #define FT_CR_RSP 17
  51
  52 static const int x86_64_ft_collect_regmap[] = {
  53   FT_CR_RAX * 8, FT_CR_RBX * 8, FT_CR_RCX * 8, FT_CR_RDX * 8,
  54   FT_CR_RSI * 8, FT_CR_RDI * 8, FT_CR_RBP * 8, FT_CR_RSP * 8,
  55   FT_CR_R8 * 8,  FT_CR_R9 * 8,  FT_CR_R10 * 8, FT_CR_R11 * 8,
  56   FT_CR_R12 * 8, FT_CR_R13 * 8, FT_CR_R14 * 8, FT_CR_R15 * 8,
  57   FT_CR_RIP * 8, FT_CR_EFLAGS * 8
  58 };
  59
  60 #define X86_64_NUM_FT_COLLECT_GREGS \
  61   (sizeof (x86_64_ft_collect_regmap) / sizeof(x86_64_ft_collect_regmap[0]))
  62
  63 void
  64 supply_fast_tracepoint_registers (struct regcache *regcache,
  65                                   const unsigned char *buf)
  66 {
  67   int i;
  68
  69   for (i = 0; i < X86_64_NUM_FT_COLLECT_GREGS; i++)
  70     supply_register (regcache, i,
  71                      ((char *) buf) + x86_64_ft_collect_regmap[i]);
  72 }
  73
  74 ULONGEST
  75 get_raw_reg (const unsigned char *raw_regs, int regnum)
  76 {
  77   if (regnum >= X86_64_NUM_FT_COLLECT_GREGS)
  78     return 0;
  79
  80   return *(ULONGEST *) (raw_regs + x86_64_ft_collect_regmap[regnum]);
  81 }
  82
  83 #ifdef HAVE_UST
  84
  85 #include <ust/processor.h>
  86
  87 /* "struct registers" is the UST object type holding the registers at
  88    the time of the static tracepoint marker call.  This doesn't
  89    contain RIP, but we know what it must have been (the marker
  90    address).  */
  91
  92 #define ST_REGENTRY(REG)                        \
  93   {                                             \
  94     offsetof (struct registers, REG),           \
  95     sizeof (((struct registers *) NULL)->REG)   \
  96   }
  97
  98 static struct
  99 {
 100   int offset;
 101   int size;
 102 } x86_64_st_collect_regmap[] =
 103   {
 104     ST_REGENTRY(rax),
 105     ST_REGENTRY(rbx),
 106     ST_REGENTRY(rcx),
 107     ST_REGENTRY(rdx),
 108     ST_REGENTRY(rsi),
 109     ST_REGENTRY(rdi),
 110     ST_REGENTRY(rbp),
 111     ST_REGENTRY(rsp),
 112     ST_REGENTRY(r8),
 113     ST_REGENTRY(r9),
 114     ST_REGENTRY(r10),
 115     ST_REGENTRY(r11),
 116     ST_REGENTRY(r12),
 117     ST_REGENTRY(r13),
 118     ST_REGENTRY(r14),
 119     ST_REGENTRY(r15),
 120     { -1, 0 },
 121     ST_REGENTRY(rflags),
 122     ST_REGENTRY(cs),
 123     ST_REGENTRY(ss),
 124   };
 125
 126 #define X86_64_NUM_ST_COLLECT_GREGS \
 127   (sizeof (x86_64_st_collect_regmap) / sizeof (x86_64_st_collect_regmap[0]))
 128
 129 /* GDB's RIP register number.  */
 130 #define AMD64_RIP_REGNUM 16
 131
 132 void
 133 supply_static_tracepoint_registers (struct regcache *regcache,
 134                                     const unsigned char *buf,
 135                                     CORE_ADDR pc)
 136 {
 137   int i;
 138   unsigned long newpc = pc;
 139
 140   supply_register (regcache, AMD64_RIP_REGNUM, &newpc);
 141
 142   for (i = 0; i < X86_64_NUM_ST_COLLECT_GREGS; i++)
 143     if (x86_64_st_collect_regmap[i].offset != -1)
 144       {
 145         switch (x86_64_st_collect_regmap[i].size)
 146           {
 147           case 8:
 148             supply_register (regcache, i,
 149                              ((char *) buf)
 150                              + x86_64_st_collect_regmap[i].offset);
 151             break;
 152           case 2:
 153             {
 154               unsigned long reg
 155                 = * (short *) (((char *) buf)
 156                                + x86_64_st_collect_regmap[i].offset);
 157               reg &= 0xffff;
 158               supply_register (regcache, i, &reg);
 159             }
 160             break;
 161           default:
 162             internal_error (__FILE__, __LINE__,
 163                             "unhandled register size: %d",
 164                             x86_64_st_collect_regmap[i].size);
 165             break;
 166           }
 167       }
 168 }
 169
 170 #endif /* HAVE_UST */
 171
 172 #if !defined __ILP32__
 173 /* Map the tdesc index to xcr0 mask.  */
 174 static uint64_t idx2mask[X86_TDESC_LAST] = {
 175   X86_XSTATE_X87_MASK,
 176   X86_XSTATE_SSE_MASK,
 177   X86_XSTATE_AVX_MASK,
 178   X86_XSTATE_MPX_MASK,
 179   X86_XSTATE_AVX_MPX_MASK,
 180   X86_XSTATE_AVX_AVX512_MASK,
 181   X86_XSTATE_AVX_MPX_AVX512_PKU_MASK,
 182 };
 183 #endif
 184
 185 /* Return target_desc to use for IPA, given the tdesc index passed by
 186    gdbserver.  */
 187
 188 const struct target_desc *
 189 get_ipa_tdesc (int idx)
 190 {
 191   if (idx >= X86_TDESC_LAST)
 192     {
 193       internal_error (__FILE__, __LINE__,
 194                       "unknown ipa tdesc index: %d", idx);
 195     }
 196
 197 #if defined __ILP32__
 198   switch (idx)
 199     {
 200     case X86_TDESC_SSE:
 201       return amd64_linux_read_description (X86_XSTATE_SSE_MASK, true);
 202     case X86_TDESC_AVX:
 203       return amd64_linux_read_description (X86_XSTATE_AVX_MASK, true);
 204     case X86_TDESC_AVX_AVX512:
 205       return amd64_linux_read_description (X86_XSTATE_AVX_AVX512_MASK, true);
 206     default:
 207       break;
 208     }
 209 #else
 210   return amd64_linux_read_description (idx2mask[idx], false);
 211 #endif
 212
 213   internal_error (__FILE__, __LINE__,
 214                   "unknown ipa tdesc index: %d", idx);
 215 }
 216
 217 /* Allocate buffer for the jump pads.  The branch instruction has a
 218    reach of +/- 31-bit, and the executable is loaded at low addresses.
 219
 220    64-bit: Use MAP_32BIT to allocate in the first 2GB.  Shared
 221    libraries, being allocated at the top, are unfortunately out of
 222    luck.
 223
 224    x32: Since MAP_32BIT is 64-bit only, do the placement manually.
 225    Try allocating at '0x80000000 - SIZE' initially, decreasing until
 226    we hit a free area.  This ensures the executable is fully covered,
 227    and is as close as possible to the shared libraries, which are
 228    usually mapped at the top of the first 4GB of the address space.
 229 */
 230
 231 void *
 232 alloc_jump_pad_buffer (size_t size)
 233 {
 234 #if __ILP32__
 235   uintptr_t addr;
 236   int pagesize;
 237
 238   pagesize = sysconf (_SC_PAGE_SIZE);
 239   if (pagesize == -1)
 240     perror_with_name ("sysconf");
 241
 242   addr = 0x80000000 - size;
 243
 244   /* size should already be page-aligned, but this can't hurt.  */
 245   addr &= ~(pagesize - 1);
 246
 247   /* Search for a free area.  If we hit 0, we're out of luck.  */
 248   for (; addr; addr -= pagesize)
 249     {
 250       void *res;
 251
 252       /* No MAP_FIXED - we don't want to zap someone's mapping.  */
 253       res = mmap ((void *) addr, size,
 254                   PROT_READ | PROT_WRITE | PROT_EXEC,
 255                   MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 256
 257       /* If we got what we wanted, return.  */
 258       if ((uintptr_t) res == addr)
 259         return res;
 260
 261       /* If we got a mapping, but at a wrong address, undo it.  */
 262       if (res != MAP_FAILED)
 263         munmap (res, size);
 264     }
 265
 266   return NULL;
 267 #else
 268   void *res = mmap (NULL, size, PROT_READ | PROT_WRITE | PROT_EXEC,
 269                     MAP_PRIVATE | MAP_ANONYMOUS | MAP_32BIT, -1, 0);
 270
 271   if (res == MAP_FAILED)
 272     return NULL;
 273
 274   return res;
 275 #endif
 276 }
 277
 278 void
 279 initialize_low_tracepoint (void)
 280 {
 281 #if defined __ILP32__
 282   amd64_linux_read_description (X86_XSTATE_SSE_MASK, true);
 283   amd64_linux_read_description (X86_XSTATE_AVX_MASK, true);
 284   amd64_linux_read_description (X86_XSTATE_AVX_AVX512_MASK, true);
 285 #else
 286   for (auto i = 0; i < X86_TDESC_LAST; i++)
 287     amd64_linux_read_description (idx2mask[i], false);
 288 #endif
 289 }