gdbserver/linux-i386-ipa.cc

   1 /* GNU/Linux/x86 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 /* GDB register numbers.  */
  27
  28 enum i386_gdb_regnum
  29 {
  30   I386_EAX_REGNUM,              /* %eax */
  31   I386_ECX_REGNUM,              /* %ecx */
  32   I386_EDX_REGNUM,              /* %edx */
  33   I386_EBX_REGNUM,              /* %ebx */
  34   I386_ESP_REGNUM,              /* %esp */
  35   I386_EBP_REGNUM,              /* %ebp */
  36   I386_ESI_REGNUM,              /* %esi */
  37   I386_EDI_REGNUM,              /* %edi */
  38   I386_EIP_REGNUM,              /* %eip */
  39   I386_EFLAGS_REGNUM,           /* %eflags */
  40   I386_CS_REGNUM,               /* %cs */
  41   I386_SS_REGNUM,               /* %ss */
  42   I386_DS_REGNUM,               /* %ds */
  43   I386_ES_REGNUM,               /* %es */
  44   I386_FS_REGNUM,               /* %fs */
  45   I386_GS_REGNUM,               /* %gs */
  46   I386_ST0_REGNUM               /* %st(0) */
  47 };
  48
  49 #define i386_num_regs 16
  50
  51 #define FT_CR_EAX 15
  52 #define FT_CR_ECX 14
  53 #define FT_CR_EDX 13
  54 #define FT_CR_EBX 12
  55 #define FT_CR_UESP 11
  56 #define FT_CR_EBP 10
  57 #define FT_CR_ESI 9
  58 #define FT_CR_EDI 8
  59 #define FT_CR_EIP 7
  60 #define FT_CR_EFL 6
  61 #define FT_CR_DS 5
  62 #define FT_CR_ES 4
  63 #define FT_CR_FS 3
  64 #define FT_CR_GS 2
  65 #define FT_CR_SS 1
  66 #define FT_CR_CS 0
  67
  68 /* Mapping between the general-purpose registers in jump tracepoint
  69    format and GDB's register array layout.  */
  70
  71 static const int i386_ft_collect_regmap[] =
  72 {
  73   FT_CR_EAX * 4, FT_CR_ECX * 4, FT_CR_EDX * 4, FT_CR_EBX * 4,
  74   FT_CR_UESP * 4, FT_CR_EBP * 4, FT_CR_ESI * 4, FT_CR_EDI * 4,
  75   FT_CR_EIP * 4, FT_CR_EFL * 4, FT_CR_CS * 4, FT_CR_SS * 4,
  76   FT_CR_DS * 4, FT_CR_ES * 4, FT_CR_FS * 4, FT_CR_GS * 4
  77 };
  78
  79 void
  80 supply_fast_tracepoint_registers (struct regcache *regcache,
  81                                   const unsigned char *buf)
  82 {
  83   int i;
  84
  85   for (i = 0; i < i386_num_regs; i++)
  86     {
  87       int regval;
  88
  89       if (i >= I386_CS_REGNUM && i <= I386_GS_REGNUM)
  90         regval = *(short *) (((char *) buf) + i386_ft_collect_regmap[i]);
  91       else
  92         regval = *(int *) (((char *) buf) + i386_ft_collect_regmap[i]);
  93
  94       supply_register (regcache, i, &regval);
  95     }
  96 }
  97
  98 ULONGEST
  99 get_raw_reg (const unsigned char *raw_regs, int regnum)
 100 {
 101   /* This should maybe be allowed to return an error code, or perhaps
 102      better, have the emit_reg detect this, and emit a constant zero,
 103      or something.  */
 104
 105   if (regnum > i386_num_regs)
 106     return 0;
 107   else if (regnum >= I386_CS_REGNUM && regnum <= I386_GS_REGNUM)
 108     return *(short *) (raw_regs + i386_ft_collect_regmap[regnum]);
 109   else
 110     return *(int *) (raw_regs + i386_ft_collect_regmap[regnum]);
 111 }
 112
 113 #ifdef HAVE_UST
 114
 115 #include <ust/processor.h>
 116
 117 /* "struct registers" is the UST object type holding the registers at
 118    the time of the static tracepoint marker call.  This doesn't
 119    contain EIP, but we know what it must have been (the marker
 120    address).  */
 121
 122 #define ST_REGENTRY(REG)                        \
 123   {                                             \
 124     offsetof (struct registers, REG),           \
 125     sizeof (((struct registers *) NULL)->REG)   \
 126   }
 127
 128 static struct
 129 {
 130   int offset;
 131   int size;
 132 } i386_st_collect_regmap[] =
 133   {
 134     ST_REGENTRY(eax),
 135     ST_REGENTRY(ecx),
 136     ST_REGENTRY(edx),
 137     ST_REGENTRY(ebx),
 138     ST_REGENTRY(esp),
 139     ST_REGENTRY(ebp),
 140     ST_REGENTRY(esi),
 141     ST_REGENTRY(edi),
 142     { -1, 0 }, /* eip */
 143     ST_REGENTRY(eflags),
 144     ST_REGENTRY(cs),
 145     ST_REGENTRY(ss),
 146   };
 147
 148 #define i386_NUM_ST_COLLECT_GREGS \
 149   (sizeof (i386_st_collect_regmap) / sizeof (i386_st_collect_regmap[0]))
 150
 151 void
 152 supply_static_tracepoint_registers (struct regcache *regcache,
 153                                     const unsigned char *buf,
 154                                     CORE_ADDR pc)
 155 {
 156   int i;
 157   unsigned int newpc = pc;
 158
 159   supply_register (regcache, I386_EIP_REGNUM, &newpc);
 160
 161   for (i = 0; i < i386_NUM_ST_COLLECT_GREGS; i++)
 162     if (i386_st_collect_regmap[i].offset != -1)
 163       {
 164         switch (i386_st_collect_regmap[i].size)
 165           {
 166           case 4:
 167             supply_register (regcache, i,
 168                              ((char *) buf)
 169                              + i386_st_collect_regmap[i].offset);
 170             break;
 171           case 2:
 172             {
 173               unsigned long reg
 174                 = * (short *) (((char *) buf)
 175                                + i386_st_collect_regmap[i].offset);
 176               reg &= 0xffff;
 177               supply_register (regcache, i, &reg);
 178             }
 179             break;
 180           default:
 181             internal_error ("unhandled register size: %d",
 182                             i386_st_collect_regmap[i].size);
 183           }
 184       }
 185 }
 186
 187 #endif /* HAVE_UST */
 188
 189
 190 /* This is only needed because reg-i386-linux-lib.o references it.  We
 191    may use it proper at some point.  */
 192 const char *gdbserver_xmltarget;
 193
 194 /* Attempt to allocate memory for trampolines in the first 64 KiB of
 195    memory to enable smaller jump patches.  */
 196
 197 static void
 198 initialize_fast_tracepoint_trampoline_buffer (void)
 199 {
 200   const CORE_ADDR buffer_end = 64 * 1024;
 201   /* Ensure that the buffer will be at least 1 KiB in size, which is
 202      enough space for over 200 fast tracepoints.  */
 203   const int min_buffer_size = 1024;
 204   char buf[IPA_BUFSIZ];
 205   CORE_ADDR mmap_min_addr = buffer_end + 1;
 206   ULONGEST buffer_size;
 207   FILE *f = fopen ("/proc/sys/vm/mmap_min_addr", "r");
 208
 209   if (!f)
 210     {
 211       snprintf (buf, sizeof (buf), "mmap_min_addr open failed: %s",
 212                 safe_strerror (errno));
 213       set_trampoline_buffer_space (0, 0, buf);
 214       return;
 215     }
 216
 217   if (fgets (buf, IPA_BUFSIZ, f))
 218     sscanf (buf, "%llu", &mmap_min_addr);
 219
 220   fclose (f);
 221
 222   buffer_size = buffer_end - mmap_min_addr;
 223
 224   if (buffer_size >= min_buffer_size)
 225     {
 226       if (mmap ((void *) (uintptr_t) mmap_min_addr, buffer_size,
 227                 PROT_READ | PROT_EXEC | PROT_WRITE,
 228                 MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS,
 229                 -1, 0)
 230           != MAP_FAILED)
 231         set_trampoline_buffer_space (mmap_min_addr, buffer_end, NULL);
 232       else
 233         {
 234           snprintf (buf, IPA_BUFSIZ, "low-64K-buffer mmap() failed: %s",
 235                     safe_strerror (errno));
 236           set_trampoline_buffer_space (0, 0, buf);
 237         }
 238     }
 239   else
 240     {
 241       snprintf (buf, IPA_BUFSIZ, "mmap_min_addr is %d, must be %d or less",
 242                 (int) mmap_min_addr, (int) buffer_end - min_buffer_size);
 243       set_trampoline_buffer_space (0, 0, buf);
 244     }
 245 }
 246
 247 /* Map the tdesc index to xcr0 mask.  */
 248 static uint64_t idx2mask[X86_TDESC_LAST] = {
 249   X86_XSTATE_X87_MASK,
 250   X86_XSTATE_SSE_MASK,
 251   X86_XSTATE_AVX_MASK,
 252   X86_XSTATE_MPX_MASK,
 253   X86_XSTATE_AVX_MPX_MASK,
 254   X86_XSTATE_AVX_AVX512_MASK,
 255   X86_XSTATE_AVX_MPX_AVX512_PKU_MASK,
 256 };
 257
 258 /* Return target_desc to use for IPA, given the tdesc index passed by
 259    gdbserver.  */
 260
 261 const struct target_desc *
 262 get_ipa_tdesc (int idx)
 263 {
 264   if (idx >= X86_TDESC_LAST)
 265     {
 266       internal_error ("unknown ipa tdesc index: %d", idx);
 267     }
 268   return i386_linux_read_description (idx2mask[idx]);
 269 }
 270
 271 /* Allocate buffer for the jump pads.  On i386, we can reach an arbitrary
 272    address with a jump instruction, so just allocate normally.  */
 273
 274 void *
 275 alloc_jump_pad_buffer (size_t size)
 276 {
 277   void *res = mmap (NULL, size, PROT_READ | PROT_WRITE | PROT_EXEC,
 278                     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 279
 280   if (res == MAP_FAILED)
 281     return NULL;
 282
 283   return res;
 284 }
 285
 286 void
 287 initialize_low_tracepoint (void)
 288 {
 289   initialize_fast_tracepoint_trampoline_buffer ();
 290   for (auto i = 0; i < X86_TDESC_LAST; i++)
 291     i386_linux_read_description (idx2mask[i]);
 292 }