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 /* Defined in auto-generated file amd64-linux.c.  */
  27 void init_registers_amd64_linux (void);
  28 extern const struct target_desc *tdesc_amd64_linux;
  29
  30 /* fast tracepoints collect registers.  */
  31
  32 #define FT_CR_RIP 0
  33 #define FT_CR_EFLAGS 1
  34 #define FT_CR_R8 2
  35 #define FT_CR_R9 3
  36 #define FT_CR_R10 4
  37 #define FT_CR_R11 5
  38 #define FT_CR_R12 6
  39 #define FT_CR_R13 7
  40 #define FT_CR_R14 8
  41 #define FT_CR_R15 9
  42 #define FT_CR_RAX 10
  43 #define FT_CR_RBX 11
  44 #define FT_CR_RCX 12
  45 #define FT_CR_RDX 13
  46 #define FT_CR_RSI 14
  47 #define FT_CR_RDI 15
  48 #define FT_CR_RBP 16
  49 #define FT_CR_RSP 17
  50
  51 static const int x86_64_ft_collect_regmap[] = {
  52   FT_CR_RAX * 8, FT_CR_RBX * 8, FT_CR_RCX * 8, FT_CR_RDX * 8,
  53   FT_CR_RSI * 8, FT_CR_RDI * 8, FT_CR_RBP * 8, FT_CR_RSP * 8,
  54   FT_CR_R8 * 8,  FT_CR_R9 * 8,  FT_CR_R10 * 8, FT_CR_R11 * 8,
  55   FT_CR_R12 * 8, FT_CR_R13 * 8, FT_CR_R14 * 8, FT_CR_R15 * 8,
  56   FT_CR_RIP * 8, FT_CR_EFLAGS * 8
  57 };
  58
  59 #define X86_64_NUM_FT_COLLECT_GREGS \
  60   (sizeof (x86_64_ft_collect_regmap) / sizeof(x86_64_ft_collect_regmap[0]))
  61
  62 void
  63 supply_fast_tracepoint_registers (struct regcache *regcache,
  64                                   const unsigned char *buf)
  65 {
  66   int i;
  67
  68   for (i = 0; i < X86_64_NUM_FT_COLLECT_GREGS; i++)
  69     supply_register (regcache, i,
  70                      ((char *) buf) + x86_64_ft_collect_regmap[i]);
  71 }
  72
  73 ULONGEST
  74 get_raw_reg (const unsigned char *raw_regs, int regnum)
  75 {
  76   if (regnum >= X86_64_NUM_FT_COLLECT_GREGS)
  77     return 0;
  78
  79   return *(ULONGEST *) (raw_regs + x86_64_ft_collect_regmap[regnum]);
  80 }
  81
  82 #ifdef HAVE_UST
  83
  84 #include <ust/processor.h>
  85
  86 /* "struct registers" is the UST object type holding the registers at
  87    the time of the static tracepoint marker call.  This doesn't
  88    contain RIP, but we know what it must have been (the marker
  89    address).  */
  90
  91 #define ST_REGENTRY(REG)                        \
  92   {                                             \
  93     offsetof (struct registers, REG),           \
  94     sizeof (((struct registers *) NULL)->REG)   \
  95   }
  96
  97 static struct
  98 {
  99   int offset;
 100   int size;
 101 } x86_64_st_collect_regmap[] =
 102   {
 103     ST_REGENTRY(rax),
 104     ST_REGENTRY(rbx),
 105     ST_REGENTRY(rcx),
 106     ST_REGENTRY(rdx),
 107     ST_REGENTRY(rsi),
 108     ST_REGENTRY(rdi),
 109     ST_REGENTRY(rbp),
 110     ST_REGENTRY(rsp),
 111     ST_REGENTRY(r8),
 112     ST_REGENTRY(r9),
 113     ST_REGENTRY(r10),
 114     ST_REGENTRY(r11),
 115     ST_REGENTRY(r12),
 116     ST_REGENTRY(r13),
 117     ST_REGENTRY(r14),
 118     ST_REGENTRY(r15),
 119     { -1, 0 },
 120     ST_REGENTRY(rflags),
 121     ST_REGENTRY(cs),
 122     ST_REGENTRY(ss),
 123   };
 124
 125 #define X86_64_NUM_ST_COLLECT_GREGS \
 126   (sizeof (x86_64_st_collect_regmap) / sizeof (x86_64_st_collect_regmap[0]))
 127
 128 /* GDB's RIP register number.  */
 129 #define AMD64_RIP_REGNUM 16
 130
 131 void
 132 supply_static_tracepoint_registers (struct regcache *regcache,
 133                                     const unsigned char *buf,
 134                                     CORE_ADDR pc)
 135 {
 136   int i;
 137   unsigned long newpc = pc;
 138
 139   supply_register (regcache, AMD64_RIP_REGNUM, &newpc);
 140
 141   for (i = 0; i < X86_64_NUM_ST_COLLECT_GREGS; i++)
 142     if (x86_64_st_collect_regmap[i].offset != -1)
 143       {
 144         switch (x86_64_st_collect_regmap[i].size)
 145           {
 146           case 8:
 147             supply_register (regcache, i,
 148                              ((char *) buf)
 149                              + x86_64_st_collect_regmap[i].offset);
 150             break;
 151           case 2:
 152             {
 153               unsigned long reg
 154                 = * (short *) (((char *) buf)
 155                                + x86_64_st_collect_regmap[i].offset);
 156               reg &= 0xffff;
 157               supply_register (regcache, i, &reg);
 158             }
 159             break;
 160           default:
 161             internal_error ("unhandled register size: %d",
 162                             x86_64_st_collect_regmap[i].size);
 163             break;
 164           }
 165       }
 166 }
 167
 168 #endif /* HAVE_UST */
 169
 170 #if !defined __ILP32__
 171 /* Map the tdesc index to xcr0 mask.  */
 172 static uint64_t idx2mask[X86_TDESC_LAST] = {
 173   X86_XSTATE_X87_MASK,
 174   X86_XSTATE_SSE_MASK,
 175   X86_XSTATE_AVX_MASK,
 176   X86_XSTATE_MPX_MASK,
 177   X86_XSTATE_AVX_MPX_MASK,
 178   X86_XSTATE_AVX_AVX512_MASK,
 179   X86_XSTATE_AVX_MPX_AVX512_PKU_MASK,
 180 };
 181 #endif
 182
 183 /* Return target_desc to use for IPA, given the tdesc index passed by
 184    gdbserver.  */
 185
 186 const struct target_desc *
 187 get_ipa_tdesc (int idx)
 188 {
 189   if (idx >= X86_TDESC_LAST)
 190     {
 191       internal_error ("unknown ipa tdesc index: %d", idx);
 192     }
 193
 194 #if defined __ILP32__
 195   switch (idx)
 196     {
 197     case X86_TDESC_SSE:
 198       return amd64_linux_read_description (X86_XSTATE_SSE_MASK, true);
 199     case X86_TDESC_AVX:
 200       return amd64_linux_read_description (X86_XSTATE_AVX_MASK, true);
 201     case X86_TDESC_AVX_AVX512:
 202       return amd64_linux_read_description (X86_XSTATE_AVX_AVX512_MASK, true);
 203     default:
 204       break;
 205     }
 206 #else
 207   return amd64_linux_read_description (idx2mask[idx], false);
 208 #endif
 209
 210   internal_error ("unknown ipa tdesc index: %d", idx);
 211 }
 212
 213 /* Allocate buffer for the jump pads.  The branch instruction has a
 214    reach of +/- 31-bit, and the executable is loaded at low addresses.
 215
 216    64-bit: Use MAP_32BIT to allocate in the first 2GB.  Shared
 217    libraries, being allocated at the top, are unfortunately out of
 218    luck.
 219
 220    x32: Since MAP_32BIT is 64-bit only, do the placement manually.
 221    Try allocating at '0x80000000 - SIZE' initially, decreasing until
 222    we hit a free area.  This ensures the executable is fully covered,
 223    and is as close as possible to the shared libraries, which are
 224    usually mapped at the top of the first 4GB of the address space.
 225 */
 226
 227 void *
 228 alloc_jump_pad_buffer (size_t size)
 229 {
 230 #if __ILP32__
 231   uintptr_t addr;
 232   int pagesize;
 233
 234   pagesize = sysconf (_SC_PAGE_SIZE);
 235   if (pagesize == -1)
 236     perror_with_name ("sysconf");
 237
 238   addr = 0x80000000 - size;
 239
 240   /* size should already be page-aligned, but this can't hurt.  */
 241   addr &= ~(pagesize - 1);
 242
 243   /* Search for a free area.  If we hit 0, we're out of luck.  */
 244   for (; addr; addr -= pagesize)
 245     {
 246       void *res;
 247
 248       /* No MAP_FIXED - we don't want to zap someone's mapping.  */
 249       res = mmap ((void *) addr, size,
 250                   PROT_READ | PROT_WRITE | PROT_EXEC,
 251                   MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 252
 253       /* If we got what we wanted, return.  */
 254       if ((uintptr_t) res == addr)
 255         return res;
 256
 257       /* If we got a mapping, but at a wrong address, undo it.  */
 258       if (res != MAP_FAILED)
 259         munmap (res, size);
 260     }
 261
 262   return NULL;
 263 #else
 264   void *res = mmap (NULL, size, PROT_READ | PROT_WRITE | PROT_EXEC,
 265                     MAP_PRIVATE | MAP_ANONYMOUS | MAP_32BIT, -1, 0);
 266
 267   if (res == MAP_FAILED)
 268     return NULL;
 269
 270   return res;
 271 #endif
 272 }
 273
 274 void
 275 initialize_low_tracepoint (void)
 276 {
 277 #if defined __ILP32__
 278   amd64_linux_read_description (X86_XSTATE_SSE_MASK, true);
 279   amd64_linux_read_description (X86_XSTATE_AVX_MASK, true);
 280   amd64_linux_read_description (X86_XSTATE_AVX_AVX512_MASK, true);
 281 #else
 282   for (auto i = 0; i < X86_TDESC_LAST; i++)
 283     amd64_linux_read_description (idx2mask[i], false);
 284 #endif
 285 }