| 1 | /* GNU/Linux/x86 specific low level interface, for the in-process |
| 2 | agent library for GDB. |
| 3 | |
| 4 | Copyright (C) 2010-2020 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 <sys/mman.h> |
| 23 | #include "tracepoint.h" |
| 24 | #include "linux-x86-tdesc.h" |
| 25 | #include "gdbsupport/x86-xstate.h" |
| 26 | |
| 27 | /* GDB register numbers. */ |
| 28 | |
| 29 | enum i386_gdb_regnum |
| 30 | { |
| 31 | I386_EAX_REGNUM, /* %eax */ |
| 32 | I386_ECX_REGNUM, /* %ecx */ |
| 33 | I386_EDX_REGNUM, /* %edx */ |
| 34 | I386_EBX_REGNUM, /* %ebx */ |
| 35 | I386_ESP_REGNUM, /* %esp */ |
| 36 | I386_EBP_REGNUM, /* %ebp */ |
| 37 | I386_ESI_REGNUM, /* %esi */ |
| 38 | I386_EDI_REGNUM, /* %edi */ |
| 39 | I386_EIP_REGNUM, /* %eip */ |
| 40 | I386_EFLAGS_REGNUM, /* %eflags */ |
| 41 | I386_CS_REGNUM, /* %cs */ |
| 42 | I386_SS_REGNUM, /* %ss */ |
| 43 | I386_DS_REGNUM, /* %ds */ |
| 44 | I386_ES_REGNUM, /* %es */ |
| 45 | I386_FS_REGNUM, /* %fs */ |
| 46 | I386_GS_REGNUM, /* %gs */ |
| 47 | I386_ST0_REGNUM /* %st(0) */ |
| 48 | }; |
| 49 | |
| 50 | #define i386_num_regs 16 |
| 51 | |
| 52 | #define FT_CR_EAX 15 |
| 53 | #define FT_CR_ECX 14 |
| 54 | #define FT_CR_EDX 13 |
| 55 | #define FT_CR_EBX 12 |
| 56 | #define FT_CR_UESP 11 |
| 57 | #define FT_CR_EBP 10 |
| 58 | #define FT_CR_ESI 9 |
| 59 | #define FT_CR_EDI 8 |
| 60 | #define FT_CR_EIP 7 |
| 61 | #define FT_CR_EFL 6 |
| 62 | #define FT_CR_DS 5 |
| 63 | #define FT_CR_ES 4 |
| 64 | #define FT_CR_FS 3 |
| 65 | #define FT_CR_GS 2 |
| 66 | #define FT_CR_SS 1 |
| 67 | #define FT_CR_CS 0 |
| 68 | |
| 69 | /* Mapping between the general-purpose registers in jump tracepoint |
| 70 | format and GDB's register array layout. */ |
| 71 | |
| 72 | static const int i386_ft_collect_regmap[] = |
| 73 | { |
| 74 | FT_CR_EAX * 4, FT_CR_ECX * 4, FT_CR_EDX * 4, FT_CR_EBX * 4, |
| 75 | FT_CR_UESP * 4, FT_CR_EBP * 4, FT_CR_ESI * 4, FT_CR_EDI * 4, |
| 76 | FT_CR_EIP * 4, FT_CR_EFL * 4, FT_CR_CS * 4, FT_CR_SS * 4, |
| 77 | FT_CR_DS * 4, FT_CR_ES * 4, FT_CR_FS * 4, FT_CR_GS * 4 |
| 78 | }; |
| 79 | |
| 80 | void |
| 81 | supply_fast_tracepoint_registers (struct regcache *regcache, |
| 82 | const unsigned char *buf) |
| 83 | { |
| 84 | int i; |
| 85 | |
| 86 | for (i = 0; i < i386_num_regs; i++) |
| 87 | { |
| 88 | int regval; |
| 89 | |
| 90 | if (i >= I386_CS_REGNUM && i <= I386_GS_REGNUM) |
| 91 | regval = *(short *) (((char *) buf) + i386_ft_collect_regmap[i]); |
| 92 | else |
| 93 | regval = *(int *) (((char *) buf) + i386_ft_collect_regmap[i]); |
| 94 | |
| 95 | supply_register (regcache, i, ®val); |
| 96 | } |
| 97 | } |
| 98 | |
| 99 | ULONGEST |
| 100 | get_raw_reg (const unsigned char *raw_regs, int regnum) |
| 101 | { |
| 102 | /* This should maybe be allowed to return an error code, or perhaps |
| 103 | better, have the emit_reg detect this, and emit a constant zero, |
| 104 | or something. */ |
| 105 | |
| 106 | if (regnum > i386_num_regs) |
| 107 | return 0; |
| 108 | else if (regnum >= I386_CS_REGNUM && regnum <= I386_GS_REGNUM) |
| 109 | return *(short *) (raw_regs + i386_ft_collect_regmap[regnum]); |
| 110 | else |
| 111 | return *(int *) (raw_regs + i386_ft_collect_regmap[regnum]); |
| 112 | } |
| 113 | |
| 114 | #ifdef HAVE_UST |
| 115 | |
| 116 | #include <ust/processor.h> |
| 117 | |
| 118 | /* "struct registers" is the UST object type holding the registers at |
| 119 | the time of the static tracepoint marker call. This doesn't |
| 120 | contain EIP, but we know what it must have been (the marker |
| 121 | address). */ |
| 122 | |
| 123 | #define ST_REGENTRY(REG) \ |
| 124 | { \ |
| 125 | offsetof (struct registers, REG), \ |
| 126 | sizeof (((struct registers *) NULL)->REG) \ |
| 127 | } |
| 128 | |
| 129 | static struct |
| 130 | { |
| 131 | int offset; |
| 132 | int size; |
| 133 | } i386_st_collect_regmap[] = |
| 134 | { |
| 135 | ST_REGENTRY(eax), |
| 136 | ST_REGENTRY(ecx), |
| 137 | ST_REGENTRY(edx), |
| 138 | ST_REGENTRY(ebx), |
| 139 | ST_REGENTRY(esp), |
| 140 | ST_REGENTRY(ebp), |
| 141 | ST_REGENTRY(esi), |
| 142 | ST_REGENTRY(edi), |
| 143 | { -1, 0 }, /* eip */ |
| 144 | ST_REGENTRY(eflags), |
| 145 | ST_REGENTRY(cs), |
| 146 | ST_REGENTRY(ss), |
| 147 | }; |
| 148 | |
| 149 | #define i386_NUM_ST_COLLECT_GREGS \ |
| 150 | (sizeof (i386_st_collect_regmap) / sizeof (i386_st_collect_regmap[0])) |
| 151 | |
| 152 | void |
| 153 | supply_static_tracepoint_registers (struct regcache *regcache, |
| 154 | const unsigned char *buf, |
| 155 | CORE_ADDR pc) |
| 156 | { |
| 157 | int i; |
| 158 | unsigned int newpc = pc; |
| 159 | |
| 160 | supply_register (regcache, I386_EIP_REGNUM, &newpc); |
| 161 | |
| 162 | for (i = 0; i < i386_NUM_ST_COLLECT_GREGS; i++) |
| 163 | if (i386_st_collect_regmap[i].offset != -1) |
| 164 | { |
| 165 | switch (i386_st_collect_regmap[i].size) |
| 166 | { |
| 167 | case 4: |
| 168 | supply_register (regcache, i, |
| 169 | ((char *) buf) |
| 170 | + i386_st_collect_regmap[i].offset); |
| 171 | break; |
| 172 | case 2: |
| 173 | { |
| 174 | unsigned long reg |
| 175 | = * (short *) (((char *) buf) |
| 176 | + i386_st_collect_regmap[i].offset); |
| 177 | reg &= 0xffff; |
| 178 | supply_register (regcache, i, ®); |
| 179 | } |
| 180 | break; |
| 181 | default: |
| 182 | internal_error (__FILE__, __LINE__, "unhandled register size: %d", |
| 183 | i386_st_collect_regmap[i].size); |
| 184 | } |
| 185 | } |
| 186 | } |
| 187 | |
| 188 | #endif /* HAVE_UST */ |
| 189 | |
| 190 | |
| 191 | /* This is only needed because reg-i386-linux-lib.o references it. We |
| 192 | may use it proper at some point. */ |
| 193 | const char *gdbserver_xmltarget; |
| 194 | |
| 195 | /* Attempt to allocate memory for trampolines in the first 64 KiB of |
| 196 | memory to enable smaller jump patches. */ |
| 197 | |
| 198 | static void |
| 199 | initialize_fast_tracepoint_trampoline_buffer (void) |
| 200 | { |
| 201 | const CORE_ADDR buffer_end = 64 * 1024; |
| 202 | /* Ensure that the buffer will be at least 1 KiB in size, which is |
| 203 | enough space for over 200 fast tracepoints. */ |
| 204 | const int min_buffer_size = 1024; |
| 205 | char buf[IPA_BUFSIZ]; |
| 206 | CORE_ADDR mmap_min_addr = buffer_end + 1; |
| 207 | ULONGEST buffer_size; |
| 208 | FILE *f = fopen ("/proc/sys/vm/mmap_min_addr", "r"); |
| 209 | |
| 210 | if (!f) |
| 211 | { |
| 212 | snprintf (buf, sizeof (buf), "mmap_min_addr open failed: %s", |
| 213 | safe_strerror (errno)); |
| 214 | set_trampoline_buffer_space (0, 0, buf); |
| 215 | return; |
| 216 | } |
| 217 | |
| 218 | if (fgets (buf, IPA_BUFSIZ, f)) |
| 219 | sscanf (buf, "%llu", &mmap_min_addr); |
| 220 | |
| 221 | fclose (f); |
| 222 | |
| 223 | buffer_size = buffer_end - mmap_min_addr; |
| 224 | |
| 225 | if (buffer_size >= min_buffer_size) |
| 226 | { |
| 227 | if (mmap ((void *) (uintptr_t) mmap_min_addr, buffer_size, |
| 228 | PROT_READ | PROT_EXEC | PROT_WRITE, |
| 229 | MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, |
| 230 | -1, 0) |
| 231 | != MAP_FAILED) |
| 232 | set_trampoline_buffer_space (mmap_min_addr, buffer_end, NULL); |
| 233 | else |
| 234 | { |
| 235 | snprintf (buf, IPA_BUFSIZ, "low-64K-buffer mmap() failed: %s", |
| 236 | safe_strerror (errno)); |
| 237 | set_trampoline_buffer_space (0, 0, buf); |
| 238 | } |
| 239 | } |
| 240 | else |
| 241 | { |
| 242 | snprintf (buf, IPA_BUFSIZ, "mmap_min_addr is %d, must be %d or less", |
| 243 | (int) mmap_min_addr, (int) buffer_end - min_buffer_size); |
| 244 | set_trampoline_buffer_space (0, 0, buf); |
| 245 | } |
| 246 | } |
| 247 | |
| 248 | /* Map the tdesc index to xcr0 mask. */ |
| 249 | static uint64_t idx2mask[X86_TDESC_LAST] = { |
| 250 | X86_XSTATE_X87_MASK, |
| 251 | X86_XSTATE_SSE_MASK, |
| 252 | X86_XSTATE_AVX_MASK, |
| 253 | X86_XSTATE_MPX_MASK, |
| 254 | X86_XSTATE_AVX_MPX_MASK, |
| 255 | X86_XSTATE_AVX_AVX512_MASK, |
| 256 | X86_XSTATE_AVX_MPX_AVX512_PKU_MASK, |
| 257 | }; |
| 258 | |
| 259 | /* Return target_desc to use for IPA, given the tdesc index passed by |
| 260 | gdbserver. */ |
| 261 | |
| 262 | const struct target_desc * |
| 263 | get_ipa_tdesc (int idx) |
| 264 | { |
| 265 | if (idx >= X86_TDESC_LAST) |
| 266 | { |
| 267 | internal_error (__FILE__, __LINE__, |
| 268 | "unknown ipa tdesc index: %d", idx); |
| 269 | } |
| 270 | return i386_linux_read_description (idx2mask[idx]); |
| 271 | } |
| 272 | |
| 273 | /* Allocate buffer for the jump pads. On i386, we can reach an arbitrary |
| 274 | address with a jump instruction, so just allocate normally. */ |
| 275 | |
| 276 | void * |
| 277 | alloc_jump_pad_buffer (size_t size) |
| 278 | { |
| 279 | void *res = mmap (NULL, size, PROT_READ | PROT_WRITE | PROT_EXEC, |
| 280 | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); |
| 281 | |
| 282 | if (res == MAP_FAILED) |
| 283 | return NULL; |
| 284 | |
| 285 | return res; |
| 286 | } |
| 287 | |
| 288 | void |
| 289 | initialize_low_tracepoint (void) |
| 290 | { |
| 291 | initialize_fast_tracepoint_trampoline_buffer (); |
| 292 | for (auto i = 0; i < X86_TDESC_LAST; i++) |
| 293 | i386_linux_read_description (idx2mask[i]); |
| 294 | } |