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) 2010-2024 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 <sys/mman.h>
  22 #include "tracepoint.h"
  23 #include "linux-x86-tdesc.h"
  24 #include "gdbsupport/x86-xstate.h"
  25
  26 /* fast tracepoints collect registers.  */
  27
  28 #define FT_CR_RIP 0
  29 #define FT_CR_EFLAGS 1
  30 #define FT_CR_R8 2
  31 #define FT_CR_R9 3
  32 #define FT_CR_R10 4
  33 #define FT_CR_R11 5
  34 #define FT_CR_R12 6
  35 #define FT_CR_R13 7
  36 #define FT_CR_R14 8
  37 #define FT_CR_R15 9
  38 #define FT_CR_RAX 10
  39 #define FT_CR_RBX 11
  40 #define FT_CR_RCX 12
  41 #define FT_CR_RDX 13
  42 #define FT_CR_RSI 14
  43 #define FT_CR_RDI 15
  44 #define FT_CR_RBP 16
  45 #define FT_CR_RSP 17
  46
  47 static const int x86_64_ft_collect_regmap[] = {
  48   FT_CR_RAX * 8, FT_CR_RBX * 8, FT_CR_RCX * 8, FT_CR_RDX * 8,
  49   FT_CR_RSI * 8, FT_CR_RDI * 8, FT_CR_RBP * 8, FT_CR_RSP * 8,
  50   FT_CR_R8 * 8,  FT_CR_R9 * 8,  FT_CR_R10 * 8, FT_CR_R11 * 8,
  51   FT_CR_R12 * 8, FT_CR_R13 * 8, FT_CR_R14 * 8, FT_CR_R15 * 8,
  52   FT_CR_RIP * 8, FT_CR_EFLAGS * 8
  53 };
  54
  55 #define X86_64_NUM_FT_COLLECT_GREGS \
  56   (sizeof (x86_64_ft_collect_regmap) / sizeof(x86_64_ft_collect_regmap[0]))
  57
  58 void
  59 supply_fast_tracepoint_registers (struct regcache *regcache,
  60                                   const unsigned char *buf)
  61 {
  62   int i;
  63
  64   for (i = 0; i < X86_64_NUM_FT_COLLECT_GREGS; i++)
  65     supply_register (regcache, i,
  66                      ((char *) buf) + x86_64_ft_collect_regmap[i]);
  67 }
  68
  69 ULONGEST
  70 get_raw_reg (const unsigned char *raw_regs, int regnum)
  71 {
  72   if (regnum >= X86_64_NUM_FT_COLLECT_GREGS)
  73     return 0;
  74
  75   return *(ULONGEST *) (raw_regs + x86_64_ft_collect_regmap[regnum]);
  76 }
  77
  78 #ifdef HAVE_UST
  79
  80 #include <ust/processor.h>
  81
  82 /* "struct registers" is the UST object type holding the registers at
  83    the time of the static tracepoint marker call.  This doesn't
  84    contain RIP, but we know what it must have been (the marker
  85    address).  */
  86
  87 #define ST_REGENTRY(REG)                        \
  88   {                                             \
  89     offsetof (struct registers, REG),           \
  90     sizeof (((struct registers *) NULL)->REG)   \
  91   }
  92
  93 static struct
  94 {
  95   int offset;
  96   int size;
  97 } x86_64_st_collect_regmap[] =
  98   {
  99     ST_REGENTRY(rax),
 100     ST_REGENTRY(rbx),
 101     ST_REGENTRY(rcx),
 102     ST_REGENTRY(rdx),
 103     ST_REGENTRY(rsi),
 104     ST_REGENTRY(rdi),
 105     ST_REGENTRY(rbp),
 106     ST_REGENTRY(rsp),
 107     ST_REGENTRY(r8),
 108     ST_REGENTRY(r9),
 109     ST_REGENTRY(r10),
 110     ST_REGENTRY(r11),
 111     ST_REGENTRY(r12),
 112     ST_REGENTRY(r13),
 113     ST_REGENTRY(r14),
 114     ST_REGENTRY(r15),
 115     { -1, 0 },
 116     ST_REGENTRY(rflags),
 117     ST_REGENTRY(cs),
 118     ST_REGENTRY(ss),
 119   };
 120
 121 #define X86_64_NUM_ST_COLLECT_GREGS \
 122   (sizeof (x86_64_st_collect_regmap) / sizeof (x86_64_st_collect_regmap[0]))
 123
 124 /* GDB's RIP register number.  */
 125 #define AMD64_RIP_REGNUM 16
 126
 127 void
 128 supply_static_tracepoint_registers (struct regcache *regcache,
 129                                     const unsigned char *buf,
 130                                     CORE_ADDR pc)
 131 {
 132   int i;
 133   unsigned long newpc = pc;
 134
 135   supply_register (regcache, AMD64_RIP_REGNUM, &newpc);
 136
 137   for (i = 0; i < X86_64_NUM_ST_COLLECT_GREGS; i++)
 138     if (x86_64_st_collect_regmap[i].offset != -1)
 139       {
 140         switch (x86_64_st_collect_regmap[i].size)
 141           {
 142           case 8:
 143             supply_register (regcache, i,
 144                              ((char *) buf)
 145                              + x86_64_st_collect_regmap[i].offset);
 146             break;
 147           case 2:
 148             {
 149               unsigned long reg
 150                 = * (short *) (((char *) buf)
 151                                + x86_64_st_collect_regmap[i].offset);
 152               reg &= 0xffff;
 153               supply_register (regcache, i, &reg);
 154             }
 155             break;
 156           default:
 157             internal_error ("unhandled register size: %d",
 158                             x86_64_st_collect_regmap[i].size);
 159             break;
 160           }
 161       }
 162 }
 163
 164 #endif /* HAVE_UST */
 165
 166 #if !defined __ILP32__
 167 /* Map the tdesc index to xcr0 mask.  */
 168 static uint64_t idx2mask[X86_TDESC_LAST] = {
 169   X86_XSTATE_X87_MASK,
 170   X86_XSTATE_SSE_MASK,
 171   X86_XSTATE_AVX_MASK,
 172   X86_XSTATE_MPX_MASK,
 173   X86_XSTATE_AVX_MPX_MASK,
 174   X86_XSTATE_AVX_AVX512_MASK,
 175   X86_XSTATE_AVX_MPX_AVX512_PKU_MASK,
 176 };
 177 #endif
 178
 179 /* Return target_desc to use for IPA, given the tdesc index passed by
 180    gdbserver.  */
 181
 182 const struct target_desc *
 183 get_ipa_tdesc (int idx)
 184 {
 185   if (idx >= X86_TDESC_LAST)
 186     {
 187       internal_error ("unknown ipa tdesc index: %d", idx);
 188     }
 189
 190 #if defined __ILP32__
 191   switch (idx)
 192     {
 193     case X86_TDESC_SSE:
 194       return amd64_linux_read_description (X86_XSTATE_SSE_MASK, true);
 195     case X86_TDESC_AVX:
 196       return amd64_linux_read_description (X86_XSTATE_AVX_MASK, true);
 197     case X86_TDESC_AVX_AVX512:
 198       return amd64_linux_read_description (X86_XSTATE_AVX_AVX512_MASK, true);
 199     default:
 200       break;
 201     }
 202 #else
 203   return amd64_linux_read_description (idx2mask[idx], false);
 204 #endif
 205
 206   internal_error ("unknown ipa tdesc index: %d", idx);
 207 }
 208
 209 /* Allocate buffer for the jump pads.  The branch instruction has a
 210    reach of +/- 31-bit, and the executable is loaded at low addresses.
 211
 212    64-bit: Use MAP_32BIT to allocate in the first 2GB.  Shared
 213    libraries, being allocated at the top, are unfortunately out of
 214    luck.
 215
 216    x32: Since MAP_32BIT is 64-bit only, do the placement manually.
 217    Try allocating at '0x80000000 - SIZE' initially, decreasing until
 218    we hit a free area.  This ensures the executable is fully covered,
 219    and is as close as possible to the shared libraries, which are
 220    usually mapped at the top of the first 4GB of the address space.
 221 */
 222
 223 void *
 224 alloc_jump_pad_buffer (size_t size)
 225 {
 226 #if __ILP32__
 227   uintptr_t addr;
 228   int pagesize;
 229
 230   pagesize = sysconf (_SC_PAGE_SIZE);
 231   if (pagesize == -1)
 232     perror_with_name ("sysconf");
 233
 234   addr = 0x80000000 - size;
 235
 236   /* size should already be page-aligned, but this can't hurt.  */
 237   addr &= ~(pagesize - 1);
 238
 239   /* Search for a free area.  If we hit 0, we're out of luck.  */
 240   for (; addr; addr -= pagesize)
 241     {
 242       void *res;
 243
 244       /* No MAP_FIXED - we don't want to zap someone's mapping.  */
 245       res = mmap ((void *) addr, size,
 246                   PROT_READ | PROT_WRITE | PROT_EXEC,
 247                   MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 248
 249       /* If we got what we wanted, return.  */
 250       if ((uintptr_t) res == addr)
 251         return res;
 252
 253       /* If we got a mapping, but at a wrong address, undo it.  */
 254       if (res != MAP_FAILED)
 255         munmap (res, size);
 256     }
 257
 258   return NULL;
 259 #else
 260   void *res = mmap (NULL, size, PROT_READ | PROT_WRITE | PROT_EXEC,
 261                     MAP_PRIVATE | MAP_ANONYMOUS | MAP_32BIT, -1, 0);
 262
 263   if (res == MAP_FAILED)
 264     return NULL;
 265
 266   return res;
 267 #endif
 268 }
 269
 270 void
 271 initialize_low_tracepoint (void)
 272 {
 273 #if defined __ILP32__
 274   amd64_linux_read_description (X86_XSTATE_SSE_MASK, true);
 275   amd64_linux_read_description (X86_XSTATE_AVX_MASK, true);
 276   amd64_linux_read_description (X86_XSTATE_AVX_AVX512_MASK, true);
 277 #else
 278   for (auto i = 0; i < X86_TDESC_LAST; i++)
 279     amd64_linux_read_description (idx2mask[i], false);
 280 #endif
 281 }