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) 2010-2012 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
  53 #define FT_CR_EAX 15
  54 #define FT_CR_ECX 14
  55 #define FT_CR_EDX 13
  56 #define FT_CR_EBX 12
  57 #define FT_CR_UESP 11
  58 #define FT_CR_EBP 10
  59 #define FT_CR_ESI 9
  60 #define FT_CR_EDI 8
  61 #define FT_CR_EIP 7
  62 #define FT_CR_EFL 6
  63 #define FT_CR_DS 5
  64 #define FT_CR_ES 4
  65 #define FT_CR_FS 3
  66 #define FT_CR_GS 2
  67 #define FT_CR_SS 1
  68 #define FT_CR_CS 0
  69
  70 /* Mapping between the general-purpose registers in jump tracepoint
  71    format and GDB's register array layout.  */
  72
  73 static const int i386_ft_collect_regmap[] =
  74 {
  75   FT_CR_EAX * 4, FT_CR_ECX * 4, FT_CR_EDX * 4, FT_CR_EBX * 4,
  76   FT_CR_UESP * 4, FT_CR_EBP * 4, FT_CR_ESI * 4, FT_CR_EDI * 4,
  77   FT_CR_EIP * 4, FT_CR_EFL * 4, FT_CR_CS * 4, FT_CR_SS * 4,
  78   FT_CR_DS * 4, FT_CR_ES * 4, FT_CR_FS * 4, FT_CR_GS * 4
  79 };
  80
  81 void
  82 supply_fast_tracepoint_registers (struct regcache *regcache,
  83                                   const unsigned char *buf)
  84 {
  85   int i;
  86
  87   for (i = 0; i < i386_num_regs; i++)
  88     {
  89       int regval;
  90
  91       if (i >= I386_CS_REGNUM && i <= I386_GS_REGNUM)
  92         regval = *(short *) (((char *) buf) + i386_ft_collect_regmap[i]);
  93       else
  94         regval = *(int *) (((char *) buf) + i386_ft_collect_regmap[i]);
  95
  96       supply_register (regcache, i, &regval);
  97     }
  98 }
  99
 100 ULONGEST __attribute__ ((visibility("default"), used))
 101 gdb_agent_get_raw_reg (unsigned char *raw_regs, int regnum)
 102 {
 103   /* This should maybe be allowed to return an error code, or perhaps
 104      better, have the emit_reg detect this, and emit a constant zero,
 105      or something.  */
 106
 107   if (regnum > i386_num_regs)
 108     return 0;
 109   else if (regnum >= I386_CS_REGNUM && regnum <= I386_GS_REGNUM)
 110     return *(short *) (raw_regs + i386_ft_collect_regmap[regnum]);
 111   else
 112     return *(int *) (raw_regs + i386_ft_collect_regmap[regnum]);
 113 }
 114
 115 #ifdef HAVE_UST
 116
 117 #include <ust/processor.h>
 118
 119 /* "struct registers" is the UST object type holding the registers at
 120    the time of the static tracepoint marker call.  This doesn't
 121    contain EIP, but we know what it must have been (the marker
 122    address).  */
 123
 124 #define ST_REGENTRY(REG)                        \
 125   {                                             \
 126     offsetof (struct registers, REG),           \
 127     sizeof (((struct registers *) NULL)->REG)   \
 128   }
 129
 130 static struct
 131 {
 132   int offset;
 133   int size;
 134 } i386_st_collect_regmap[] =
 135   {
 136     ST_REGENTRY(eax),
 137     ST_REGENTRY(ecx),
 138     ST_REGENTRY(edx),
 139     ST_REGENTRY(ebx),
 140     ST_REGENTRY(esp),
 141     ST_REGENTRY(ebp),
 142     ST_REGENTRY(esi),
 143     ST_REGENTRY(edi),
 144     { -1, 0 }, /* eip */
 145     ST_REGENTRY(eflags),
 146     ST_REGENTRY(cs),
 147     ST_REGENTRY(ss),
 148   };
 149
 150 #define i386_NUM_ST_COLLECT_GREGS \
 151   (sizeof (i386_st_collect_regmap) / sizeof (i386_st_collect_regmap[0]))
 152
 153 void
 154 supply_static_tracepoint_registers (struct regcache *regcache,
 155                                     const unsigned char *buf,
 156                                     CORE_ADDR pc)
 157 {
 158   int i;
 159   unsigned int newpc = pc;
 160
 161   supply_register (regcache, I386_EIP_REGNUM, &newpc);
 162
 163   for (i = 0; i < i386_NUM_ST_COLLECT_GREGS; i++)
 164     if (i386_st_collect_regmap[i].offset != -1)
 165       {
 166         switch (i386_st_collect_regmap[i].size)
 167           {
 168           case 4:
 169             supply_register (regcache, i,
 170                              ((char *) buf)
 171                              + i386_st_collect_regmap[i].offset);
 172             break;
 173           case 2:
 174             {
 175               unsigned long reg
 176                 = * (short *) (((char *) buf)
 177                                + i386_st_collect_regmap[i].offset);
 178               reg &= 0xffff;
 179               supply_register (regcache, i, &reg);
 180             }
 181             break;
 182           default:
 183             internal_error (__FILE__, __LINE__, "unhandled register size: %d",
 184                             i386_st_collect_regmap[i].size);
 185           }
 186       }
 187 }
 188
 189 #endif /* HAVE_UST */
 190
 191
 192 /* This is only needed because reg-i386-linux-lib.o references it.  We
 193    may use it proper at some point.  */
 194 const char *gdbserver_xmltarget;
 195
 196 /* Attempt to allocate memory for trampolines in the first 64 KiB of
 197    memory to enable smaller jump patches.  */
 198
 199 static void
 200 initialize_fast_tracepoint_trampoline_buffer (void)
 201 {
 202   const CORE_ADDR buffer_end = 64 * 1024;
 203   /* Ensure that the buffer will be at least 1 KiB in size, which is
 204      enough space for over 200 fast tracepoints.  */
 205   const int min_buffer_size = 1024;
 206   char buf[IPA_BUFSIZ];
 207   CORE_ADDR mmap_min_addr = buffer_end + 1;
 208   ULONGEST buffer_size;
 209   FILE *f = fopen ("/proc/sys/vm/mmap_min_addr", "r");
 210
 211   if (!f)
 212     {
 213       snprintf (buf, sizeof (buf), "mmap_min_addr open failed: %s",
 214                 strerror (errno));
 215       set_trampoline_buffer_space (0, 0, buf);
 216       return;
 217     }
 218
 219   if (fgets (buf, IPA_BUFSIZ, f))
 220     sscanf (buf, "%llu", &mmap_min_addr);
 221
 222   fclose (f);
 223
 224   buffer_size = buffer_end - mmap_min_addr;
 225
 226   if (buffer_size >= min_buffer_size)
 227     {
 228       if (mmap ((void *) (uintptr_t) mmap_min_addr, buffer_size,
 229                 PROT_READ | PROT_EXEC | PROT_WRITE,
 230                 MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS,
 231                 -1, 0)
 232           != MAP_FAILED)
 233         set_trampoline_buffer_space (mmap_min_addr, buffer_end, NULL);
 234       else
 235         {
 236           snprintf (buf, IPA_BUFSIZ, "low-64K-buffer mmap() failed: %s",
 237                     strerror (errno));
 238           set_trampoline_buffer_space (0, 0, buf);
 239         }
 240     }
 241   else
 242     {
 243       snprintf (buf, IPA_BUFSIZ, "mmap_min_addr is %d, must be %d or less",
 244                 (int) mmap_min_addr, (int) buffer_end - min_buffer_size);
 245       set_trampoline_buffer_space (0, 0, buf);
 246     }
 247 }
 248
 249 void
 250 initialize_low_tracepoint (void)
 251 {
 252   init_registers_i386_linux ();
 253   initialize_fast_tracepoint_trampoline_buffer ();
 254 }