gdb/gdbserver/linux-i386-ipa.c

   1 /* GNU/Linux/x86 specific low level interface, for the in-process
   2    agent library for GDB.
   3
   4    Copyright (C) 2010-2013 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 <stdint.h>
  23 #include <sys/mman.h>
  24
  25 /* GDB register numbers.  */
  26
  27 enum i386_gdb_regnum
  28 {
  29   I386_EAX_REGNUM,              /* %eax */
  30   I386_ECX_REGNUM,              /* %ecx */
  31   I386_EDX_REGNUM,              /* %edx */
  32   I386_EBX_REGNUM,              /* %ebx */
  33   I386_ESP_REGNUM,              /* %esp */
  34   I386_EBP_REGNUM,              /* %ebp */
  35   I386_ESI_REGNUM,              /* %esi */
  36   I386_EDI_REGNUM,              /* %edi */
  37   I386_EIP_REGNUM,              /* %eip */
  38   I386_EFLAGS_REGNUM,           /* %eflags */
  39   I386_CS_REGNUM,               /* %cs */
  40   I386_SS_REGNUM,               /* %ss */
  41   I386_DS_REGNUM,               /* %ds */
  42   I386_ES_REGNUM,               /* %es */
  43   I386_FS_REGNUM,               /* %fs */
  44   I386_GS_REGNUM,               /* %gs */
  45   I386_ST0_REGNUM               /* %st(0) */
  46 };
  47
  48 #define i386_num_regs 16
  49
  50 /* Defined in auto-generated file i386-linux.c.  */
  51 void init_registers_i386_linux (void);
  52 extern const struct target_desc *tdesc_i386_linux;
  53
  54 #define FT_CR_EAX 15
  55 #define FT_CR_ECX 14
  56 #define FT_CR_EDX 13
  57 #define FT_CR_EBX 12
  58 #define FT_CR_UESP 11
  59 #define FT_CR_EBP 10
  60 #define FT_CR_ESI 9
  61 #define FT_CR_EDI 8
  62 #define FT_CR_EIP 7
  63 #define FT_CR_EFL 6
  64 #define FT_CR_DS 5
  65 #define FT_CR_ES 4
  66 #define FT_CR_FS 3
  67 #define FT_CR_GS 2
  68 #define FT_CR_SS 1
  69 #define FT_CR_CS 0
  70
  71 /* Mapping between the general-purpose registers in jump tracepoint
  72    format and GDB's register array layout.  */
  73
  74 static const int i386_ft_collect_regmap[] =
  75 {
  76   FT_CR_EAX * 4, FT_CR_ECX * 4, FT_CR_EDX * 4, FT_CR_EBX * 4,
  77   FT_CR_UESP * 4, FT_CR_EBP * 4, FT_CR_ESI * 4, FT_CR_EDI * 4,
  78   FT_CR_EIP * 4, FT_CR_EFL * 4, FT_CR_CS * 4, FT_CR_SS * 4,
  79   FT_CR_DS * 4, FT_CR_ES * 4, FT_CR_FS * 4, FT_CR_GS * 4
  80 };
  81
  82 void
  83 supply_fast_tracepoint_registers (struct regcache *regcache,
  84                                   const unsigned char *buf)
  85 {
  86   int i;
  87
  88   for (i = 0; i < i386_num_regs; i++)
  89     {
  90       int regval;
  91
  92       if (i >= I386_CS_REGNUM && i <= I386_GS_REGNUM)
  93         regval = *(short *) (((char *) buf) + i386_ft_collect_regmap[i]);
  94       else
  95         regval = *(int *) (((char *) buf) + i386_ft_collect_regmap[i]);
  96
  97       supply_register (regcache, i, &regval);
  98     }
  99 }
 100
 101 ULONGEST __attribute__ ((visibility("default"), used))
 102 gdb_agent_get_raw_reg (unsigned char *raw_regs, int regnum)
 103 {
 104   /* This should maybe be allowed to return an error code, or perhaps
 105      better, have the emit_reg detect this, and emit a constant zero,
 106      or something.  */
 107
 108   if (regnum > i386_num_regs)
 109     return 0;
 110   else if (regnum >= I386_CS_REGNUM && regnum <= I386_GS_REGNUM)
 111     return *(short *) (raw_regs + i386_ft_collect_regmap[regnum]);
 112   else
 113     return *(int *) (raw_regs + i386_ft_collect_regmap[regnum]);
 114 }
 115
 116 #ifdef HAVE_UST
 117
 118 #include <ust/processor.h>
 119
 120 /* "struct registers" is the UST object type holding the registers at
 121    the time of the static tracepoint marker call.  This doesn't
 122    contain EIP, but we know what it must have been (the marker
 123    address).  */
 124
 125 #define ST_REGENTRY(REG)                        \
 126   {                                             \
 127     offsetof (struct registers, REG),           \
 128     sizeof (((struct registers *) NULL)->REG)   \
 129   }
 130
 131 static struct
 132 {
 133   int offset;
 134   int size;
 135 } i386_st_collect_regmap[] =
 136   {
 137     ST_REGENTRY(eax),
 138     ST_REGENTRY(ecx),
 139     ST_REGENTRY(edx),
 140     ST_REGENTRY(ebx),
 141     ST_REGENTRY(esp),
 142     ST_REGENTRY(ebp),
 143     ST_REGENTRY(esi),
 144     ST_REGENTRY(edi),
 145     { -1, 0 }, /* eip */
 146     ST_REGENTRY(eflags),
 147     ST_REGENTRY(cs),
 148     ST_REGENTRY(ss),
 149   };
 150
 151 #define i386_NUM_ST_COLLECT_GREGS \
 152   (sizeof (i386_st_collect_regmap) / sizeof (i386_st_collect_regmap[0]))
 153
 154 void
 155 supply_static_tracepoint_registers (struct regcache *regcache,
 156                                     const unsigned char *buf,
 157                                     CORE_ADDR pc)
 158 {
 159   int i;
 160   unsigned int newpc = pc;
 161
 162   supply_register (regcache, I386_EIP_REGNUM, &newpc);
 163
 164   for (i = 0; i < i386_NUM_ST_COLLECT_GREGS; i++)
 165     if (i386_st_collect_regmap[i].offset != -1)
 166       {
 167         switch (i386_st_collect_regmap[i].size)
 168           {
 169           case 4:
 170             supply_register (regcache, i,
 171                              ((char *) buf)
 172                              + i386_st_collect_regmap[i].offset);
 173             break;
 174           case 2:
 175             {
 176               unsigned long reg
 177                 = * (short *) (((char *) buf)
 178                                + i386_st_collect_regmap[i].offset);
 179               reg &= 0xffff;
 180               supply_register (regcache, i, &reg);
 181             }
 182             break;
 183           default:
 184             internal_error (__FILE__, __LINE__, "unhandled register size: %d",
 185                             i386_st_collect_regmap[i].size);
 186           }
 187       }
 188 }
 189
 190 #endif /* HAVE_UST */
 191
 192
 193 /* This is only needed because reg-i386-linux-lib.o references it.  We
 194    may use it proper at some point.  */
 195 const char *gdbserver_xmltarget;
 196
 197 /* Attempt to allocate memory for trampolines in the first 64 KiB of
 198    memory to enable smaller jump patches.  */
 199
 200 static void
 201 initialize_fast_tracepoint_trampoline_buffer (void)
 202 {
 203   const CORE_ADDR buffer_end = 64 * 1024;
 204   /* Ensure that the buffer will be at least 1 KiB in size, which is
 205      enough space for over 200 fast tracepoints.  */
 206   const int min_buffer_size = 1024;
 207   char buf[IPA_BUFSIZ];
 208   CORE_ADDR mmap_min_addr = buffer_end + 1;
 209   ULONGEST buffer_size;
 210   FILE *f = fopen ("/proc/sys/vm/mmap_min_addr", "r");
 211
 212   if (!f)
 213     {
 214       snprintf (buf, sizeof (buf), "mmap_min_addr open failed: %s",
 215                 strerror (errno));
 216       set_trampoline_buffer_space (0, 0, buf);
 217       return;
 218     }
 219
 220   if (fgets (buf, IPA_BUFSIZ, f))
 221     sscanf (buf, "%llu", &mmap_min_addr);
 222
 223   fclose (f);
 224
 225   buffer_size = buffer_end - mmap_min_addr;
 226
 227   if (buffer_size >= min_buffer_size)
 228     {
 229       if (mmap ((void *) (uintptr_t) mmap_min_addr, buffer_size,
 230                 PROT_READ | PROT_EXEC | PROT_WRITE,
 231                 MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS,
 232                 -1, 0)
 233           != MAP_FAILED)
 234         set_trampoline_buffer_space (mmap_min_addr, buffer_end, NULL);
 235       else
 236         {
 237           snprintf (buf, IPA_BUFSIZ, "low-64K-buffer mmap() failed: %s",
 238                     strerror (errno));
 239           set_trampoline_buffer_space (0, 0, buf);
 240         }
 241     }
 242   else
 243     {
 244       snprintf (buf, IPA_BUFSIZ, "mmap_min_addr is %d, must be %d or less",
 245                 (int) mmap_min_addr, (int) buffer_end - min_buffer_size);
 246       set_trampoline_buffer_space (0, 0, buf);
 247     }
 248 }
 249
 250 void
 251 initialize_low_tracepoint (void)
 252 {
 253   init_registers_i386_linux ();
 254   ipa_tdesc = tdesc_i386_linux;
 255   initialize_fast_tracepoint_trampoline_buffer ();
 256 }