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) 2010-2015 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 #include "tracepoint.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 /* Defined in auto-generated file i386-linux.c.  */
  52 void init_registers_i386_linux (void);
  53 extern const struct target_desc *tdesc_i386_linux;
  54
  55 #define FT_CR_EAX 15
  56 #define FT_CR_ECX 14
  57 #define FT_CR_EDX 13
  58 #define FT_CR_EBX 12
  59 #define FT_CR_UESP 11
  60 #define FT_CR_EBP 10
  61 #define FT_CR_ESI 9
  62 #define FT_CR_EDI 8
  63 #define FT_CR_EIP 7
  64 #define FT_CR_EFL 6
  65 #define FT_CR_DS 5
  66 #define FT_CR_ES 4
  67 #define FT_CR_FS 3
  68 #define FT_CR_GS 2
  69 #define FT_CR_SS 1
  70 #define FT_CR_CS 0
  71
  72 /* Mapping between the general-purpose registers in jump tracepoint
  73    format and GDB's register array layout.  */
  74
  75 static const int i386_ft_collect_regmap[] =
  76 {
  77   FT_CR_EAX * 4, FT_CR_ECX * 4, FT_CR_EDX * 4, FT_CR_EBX * 4,
  78   FT_CR_UESP * 4, FT_CR_EBP * 4, FT_CR_ESI * 4, FT_CR_EDI * 4,
  79   FT_CR_EIP * 4, FT_CR_EFL * 4, FT_CR_CS * 4, FT_CR_SS * 4,
  80   FT_CR_DS * 4, FT_CR_ES * 4, FT_CR_FS * 4, FT_CR_GS * 4
  81 };
  82
  83 void
  84 supply_fast_tracepoint_registers (struct regcache *regcache,
  85                                   const unsigned char *buf)
  86 {
  87   int i;
  88
  89   for (i = 0; i < i386_num_regs; i++)
  90     {
  91       int regval;
  92
  93       if (i >= I386_CS_REGNUM && i <= I386_GS_REGNUM)
  94         regval = *(short *) (((char *) buf) + i386_ft_collect_regmap[i]);
  95       else
  96         regval = *(int *) (((char *) buf) + i386_ft_collect_regmap[i]);
  97
  98       supply_register (regcache, i, &regval);
  99     }
 100 }
 101
 102 IP_AGENT_EXPORT_FUNC ULONGEST
 103 gdb_agent_get_raw_reg (unsigned char *raw_regs, int regnum)
 104 {
 105   /* This should maybe be allowed to return an error code, or perhaps
 106      better, have the emit_reg detect this, and emit a constant zero,
 107      or something.  */
 108
 109   if (regnum > i386_num_regs)
 110     return 0;
 111   else if (regnum >= I386_CS_REGNUM && regnum <= I386_GS_REGNUM)
 112     return *(short *) (raw_regs + i386_ft_collect_regmap[regnum]);
 113   else
 114     return *(int *) (raw_regs + i386_ft_collect_regmap[regnum]);
 115 }
 116
 117 #ifdef HAVE_UST
 118
 119 #include <ust/processor.h>
 120
 121 /* "struct registers" is the UST object type holding the registers at
 122    the time of the static tracepoint marker call.  This doesn't
 123    contain EIP, but we know what it must have been (the marker
 124    address).  */
 125
 126 #define ST_REGENTRY(REG)                        \
 127   {                                             \
 128     offsetof (struct registers, REG),           \
 129     sizeof (((struct registers *) NULL)->REG)   \
 130   }
 131
 132 static struct
 133 {
 134   int offset;
 135   int size;
 136 } i386_st_collect_regmap[] =
 137   {
 138     ST_REGENTRY(eax),
 139     ST_REGENTRY(ecx),
 140     ST_REGENTRY(edx),
 141     ST_REGENTRY(ebx),
 142     ST_REGENTRY(esp),
 143     ST_REGENTRY(ebp),
 144     ST_REGENTRY(esi),
 145     ST_REGENTRY(edi),
 146     { -1, 0 }, /* eip */
 147     ST_REGENTRY(eflags),
 148     ST_REGENTRY(cs),
 149     ST_REGENTRY(ss),
 150   };
 151
 152 #define i386_NUM_ST_COLLECT_GREGS \
 153   (sizeof (i386_st_collect_regmap) / sizeof (i386_st_collect_regmap[0]))
 154
 155 void
 156 supply_static_tracepoint_registers (struct regcache *regcache,
 157                                     const unsigned char *buf,
 158                                     CORE_ADDR pc)
 159 {
 160   int i;
 161   unsigned int newpc = pc;
 162
 163   supply_register (regcache, I386_EIP_REGNUM, &newpc);
 164
 165   for (i = 0; i < i386_NUM_ST_COLLECT_GREGS; i++)
 166     if (i386_st_collect_regmap[i].offset != -1)
 167       {
 168         switch (i386_st_collect_regmap[i].size)
 169           {
 170           case 4:
 171             supply_register (regcache, i,
 172                              ((char *) buf)
 173                              + i386_st_collect_regmap[i].offset);
 174             break;
 175           case 2:
 176             {
 177               unsigned long reg
 178                 = * (short *) (((char *) buf)
 179                                + i386_st_collect_regmap[i].offset);
 180               reg &= 0xffff;
 181               supply_register (regcache, i, &reg);
 182             }
 183             break;
 184           default:
 185             internal_error (__FILE__, __LINE__, "unhandled register size: %d",
 186                             i386_st_collect_regmap[i].size);
 187           }
 188       }
 189 }
 190
 191 #endif /* HAVE_UST */
 192
 193
 194 /* This is only needed because reg-i386-linux-lib.o references it.  We
 195    may use it proper at some point.  */
 196 const char *gdbserver_xmltarget;
 197
 198 /* Attempt to allocate memory for trampolines in the first 64 KiB of
 199    memory to enable smaller jump patches.  */
 200
 201 static void
 202 initialize_fast_tracepoint_trampoline_buffer (void)
 203 {
 204   const CORE_ADDR buffer_end = 64 * 1024;
 205   /* Ensure that the buffer will be at least 1 KiB in size, which is
 206      enough space for over 200 fast tracepoints.  */
 207   const int min_buffer_size = 1024;
 208   char buf[IPA_BUFSIZ];
 209   CORE_ADDR mmap_min_addr = buffer_end + 1;
 210   ULONGEST buffer_size;
 211   FILE *f = fopen ("/proc/sys/vm/mmap_min_addr", "r");
 212
 213   if (!f)
 214     {
 215       snprintf (buf, sizeof (buf), "mmap_min_addr open failed: %s",
 216                 strerror (errno));
 217       set_trampoline_buffer_space (0, 0, buf);
 218       return;
 219     }
 220
 221   if (fgets (buf, IPA_BUFSIZ, f))
 222     sscanf (buf, "%llu", &mmap_min_addr);
 223
 224   fclose (f);
 225
 226   buffer_size = buffer_end - mmap_min_addr;
 227
 228   if (buffer_size >= min_buffer_size)
 229     {
 230       if (mmap ((void *) (uintptr_t) mmap_min_addr, buffer_size,
 231                 PROT_READ | PROT_EXEC | PROT_WRITE,
 232                 MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS,
 233                 -1, 0)
 234           != MAP_FAILED)
 235         set_trampoline_buffer_space (mmap_min_addr, buffer_end, NULL);
 236       else
 237         {
 238           snprintf (buf, IPA_BUFSIZ, "low-64K-buffer mmap() failed: %s",
 239                     strerror (errno));
 240           set_trampoline_buffer_space (0, 0, buf);
 241         }
 242     }
 243   else
 244     {
 245       snprintf (buf, IPA_BUFSIZ, "mmap_min_addr is %d, must be %d or less",
 246                 (int) mmap_min_addr, (int) buffer_end - min_buffer_size);
 247       set_trampoline_buffer_space (0, 0, buf);
 248     }
 249 }
 250
 251 void
 252 initialize_low_tracepoint (void)
 253 {
 254   init_registers_i386_linux ();
 255   ipa_tdesc = tdesc_i386_linux;
 256   initialize_fast_tracepoint_trampoline_buffer ();
 257 }