| 1 | /* Target-dependent code for GNU/Linux m32r. |
| 2 | |
| 3 | Copyright (C) 2004-2013 Free Software Foundation, Inc. |
| 4 | |
| 5 | This file is part of GDB. |
| 6 | |
| 7 | This program is free software; you can redistribute it and/or modify |
| 8 | it under the terms of the GNU General Public License as published by |
| 9 | the Free Software Foundation; either version 3 of the License, or |
| 10 | (at your option) any later version. |
| 11 | |
| 12 | This program is distributed in the hope that it will be useful, |
| 13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 15 | GNU General Public License for more details. |
| 16 | |
| 17 | You should have received a copy of the GNU General Public License |
| 18 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 19 | |
| 20 | #include "defs.h" |
| 21 | #include "gdbcore.h" |
| 22 | #include "frame.h" |
| 23 | #include "value.h" |
| 24 | #include "regcache.h" |
| 25 | #include "inferior.h" |
| 26 | #include "osabi.h" |
| 27 | #include "reggroups.h" |
| 28 | #include "regset.h" |
| 29 | |
| 30 | #include "gdb_string.h" |
| 31 | |
| 32 | #include "glibc-tdep.h" |
| 33 | #include "solib-svr4.h" |
| 34 | #include "symtab.h" |
| 35 | |
| 36 | #include "trad-frame.h" |
| 37 | #include "frame-unwind.h" |
| 38 | |
| 39 | #include "m32r-tdep.h" |
| 40 | #include "linux-tdep.h" |
| 41 | |
| 42 | \f |
| 43 | |
| 44 | /* Recognizing signal handler frames. */ |
| 45 | |
| 46 | /* GNU/Linux has two flavors of signals. Normal signal handlers, and |
| 47 | "realtime" (RT) signals. The RT signals can provide additional |
| 48 | information to the signal handler if the SA_SIGINFO flag is set |
| 49 | when establishing a signal handler using `sigaction'. It is not |
| 50 | unlikely that future versions of GNU/Linux will support SA_SIGINFO |
| 51 | for normal signals too. */ |
| 52 | |
| 53 | /* When the m32r Linux kernel calls a signal handler and the |
| 54 | SA_RESTORER flag isn't set, the return address points to a bit of |
| 55 | code on the stack. This function returns whether the PC appears to |
| 56 | be within this bit of code. |
| 57 | |
| 58 | The instruction sequence for normal signals is |
| 59 | ldi r7, #__NR_sigreturn |
| 60 | trap #2 |
| 61 | or 0x67 0x77 0x10 0xf2. |
| 62 | |
| 63 | Checking for the code sequence should be somewhat reliable, because |
| 64 | the effect is to call the system call sigreturn. This is unlikely |
| 65 | to occur anywhere other than in a signal trampoline. |
| 66 | |
| 67 | It kind of sucks that we have to read memory from the process in |
| 68 | order to identify a signal trampoline, but there doesn't seem to be |
| 69 | any other way. Therefore we only do the memory reads if no |
| 70 | function name could be identified, which should be the case since |
| 71 | the code is on the stack. |
| 72 | |
| 73 | Detection of signal trampolines for handlers that set the |
| 74 | SA_RESTORER flag is in general not possible. Unfortunately this is |
| 75 | what the GNU C Library has been doing for quite some time now. |
| 76 | However, as of version 2.1.2, the GNU C Library uses signal |
| 77 | trampolines (named __restore and __restore_rt) that are identical |
| 78 | to the ones used by the kernel. Therefore, these trampolines are |
| 79 | supported too. */ |
| 80 | |
| 81 | static const gdb_byte linux_sigtramp_code[] = { |
| 82 | 0x67, 0x77, 0x10, 0xf2, |
| 83 | }; |
| 84 | |
| 85 | /* If PC is in a sigtramp routine, return the address of the start of |
| 86 | the routine. Otherwise, return 0. */ |
| 87 | |
| 88 | static CORE_ADDR |
| 89 | m32r_linux_sigtramp_start (CORE_ADDR pc, struct frame_info *this_frame) |
| 90 | { |
| 91 | gdb_byte buf[4]; |
| 92 | |
| 93 | /* We only recognize a signal trampoline if PC is at the start of |
| 94 | one of the instructions. We optimize for finding the PC at the |
| 95 | start of the instruction sequence, as will be the case when the |
| 96 | trampoline is not the first frame on the stack. We assume that |
| 97 | in the case where the PC is not at the start of the instruction |
| 98 | sequence, there will be a few trailing readable bytes on the |
| 99 | stack. */ |
| 100 | |
| 101 | if (pc % 2 != 0) |
| 102 | { |
| 103 | if (!safe_frame_unwind_memory (this_frame, pc, buf, 2)) |
| 104 | return 0; |
| 105 | |
| 106 | if (memcmp (buf, linux_sigtramp_code, 2) == 0) |
| 107 | pc -= 2; |
| 108 | else |
| 109 | return 0; |
| 110 | } |
| 111 | |
| 112 | if (!safe_frame_unwind_memory (this_frame, pc, buf, 4)) |
| 113 | return 0; |
| 114 | |
| 115 | if (memcmp (buf, linux_sigtramp_code, 4) != 0) |
| 116 | return 0; |
| 117 | |
| 118 | return pc; |
| 119 | } |
| 120 | |
| 121 | /* This function does the same for RT signals. Here the instruction |
| 122 | sequence is |
| 123 | ldi r7, #__NR_rt_sigreturn |
| 124 | trap #2 |
| 125 | or 0x97 0xf0 0x00 0xad 0x10 0xf2 0xf0 0x00. |
| 126 | |
| 127 | The effect is to call the system call rt_sigreturn. */ |
| 128 | |
| 129 | static const gdb_byte linux_rt_sigtramp_code[] = { |
| 130 | 0x97, 0xf0, 0x00, 0xad, 0x10, 0xf2, 0xf0, 0x00, |
| 131 | }; |
| 132 | |
| 133 | /* If PC is in a RT sigtramp routine, return the address of the start |
| 134 | of the routine. Otherwise, return 0. */ |
| 135 | |
| 136 | static CORE_ADDR |
| 137 | m32r_linux_rt_sigtramp_start (CORE_ADDR pc, struct frame_info *this_frame) |
| 138 | { |
| 139 | gdb_byte buf[4]; |
| 140 | |
| 141 | /* We only recognize a signal trampoline if PC is at the start of |
| 142 | one of the instructions. We optimize for finding the PC at the |
| 143 | start of the instruction sequence, as will be the case when the |
| 144 | trampoline is not the first frame on the stack. We assume that |
| 145 | in the case where the PC is not at the start of the instruction |
| 146 | sequence, there will be a few trailing readable bytes on the |
| 147 | stack. */ |
| 148 | |
| 149 | if (pc % 2 != 0) |
| 150 | return 0; |
| 151 | |
| 152 | if (!safe_frame_unwind_memory (this_frame, pc, buf, 4)) |
| 153 | return 0; |
| 154 | |
| 155 | if (memcmp (buf, linux_rt_sigtramp_code, 4) == 0) |
| 156 | { |
| 157 | if (!safe_frame_unwind_memory (this_frame, pc + 4, buf, 4)) |
| 158 | return 0; |
| 159 | |
| 160 | if (memcmp (buf, linux_rt_sigtramp_code + 4, 4) == 0) |
| 161 | return pc; |
| 162 | } |
| 163 | else if (memcmp (buf, linux_rt_sigtramp_code + 4, 4) == 0) |
| 164 | { |
| 165 | if (!safe_frame_unwind_memory (this_frame, pc - 4, buf, 4)) |
| 166 | return 0; |
| 167 | |
| 168 | if (memcmp (buf, linux_rt_sigtramp_code, 4) == 0) |
| 169 | return pc - 4; |
| 170 | } |
| 171 | |
| 172 | return 0; |
| 173 | } |
| 174 | |
| 175 | static int |
| 176 | m32r_linux_pc_in_sigtramp (CORE_ADDR pc, const char *name, |
| 177 | struct frame_info *this_frame) |
| 178 | { |
| 179 | /* If we have NAME, we can optimize the search. The trampolines are |
| 180 | named __restore and __restore_rt. However, they aren't dynamically |
| 181 | exported from the shared C library, so the trampoline may appear to |
| 182 | be part of the preceding function. This should always be sigaction, |
| 183 | __sigaction, or __libc_sigaction (all aliases to the same function). */ |
| 184 | if (name == NULL || strstr (name, "sigaction") != NULL) |
| 185 | return (m32r_linux_sigtramp_start (pc, this_frame) != 0 |
| 186 | || m32r_linux_rt_sigtramp_start (pc, this_frame) != 0); |
| 187 | |
| 188 | return (strcmp ("__restore", name) == 0 |
| 189 | || strcmp ("__restore_rt", name) == 0); |
| 190 | } |
| 191 | |
| 192 | /* From <asm/sigcontext.h>. */ |
| 193 | static int m32r_linux_sc_reg_offset[] = { |
| 194 | 4 * 4, /* r0 */ |
| 195 | 5 * 4, /* r1 */ |
| 196 | 6 * 4, /* r2 */ |
| 197 | 7 * 4, /* r3 */ |
| 198 | 0 * 4, /* r4 */ |
| 199 | 1 * 4, /* r5 */ |
| 200 | 2 * 4, /* r6 */ |
| 201 | 8 * 4, /* r7 */ |
| 202 | 9 * 4, /* r8 */ |
| 203 | 10 * 4, /* r9 */ |
| 204 | 11 * 4, /* r10 */ |
| 205 | 12 * 4, /* r11 */ |
| 206 | 13 * 4, /* r12 */ |
| 207 | 21 * 4, /* fp */ |
| 208 | 22 * 4, /* lr */ |
| 209 | -1 * 4, /* sp */ |
| 210 | 16 * 4, /* psw */ |
| 211 | -1 * 4, /* cbr */ |
| 212 | 23 * 4, /* spi */ |
| 213 | 20 * 4, /* spu */ |
| 214 | 19 * 4, /* bpc */ |
| 215 | 17 * 4, /* pc */ |
| 216 | 15 * 4, /* accl */ |
| 217 | 14 * 4 /* acch */ |
| 218 | }; |
| 219 | |
| 220 | struct m32r_frame_cache |
| 221 | { |
| 222 | CORE_ADDR base, pc; |
| 223 | struct trad_frame_saved_reg *saved_regs; |
| 224 | }; |
| 225 | |
| 226 | static struct m32r_frame_cache * |
| 227 | m32r_linux_sigtramp_frame_cache (struct frame_info *this_frame, |
| 228 | void **this_cache) |
| 229 | { |
| 230 | struct m32r_frame_cache *cache; |
| 231 | CORE_ADDR sigcontext_addr, addr; |
| 232 | int regnum; |
| 233 | |
| 234 | if ((*this_cache) != NULL) |
| 235 | return (*this_cache); |
| 236 | cache = FRAME_OBSTACK_ZALLOC (struct m32r_frame_cache); |
| 237 | (*this_cache) = cache; |
| 238 | cache->saved_regs = trad_frame_alloc_saved_regs (this_frame); |
| 239 | |
| 240 | cache->base = get_frame_register_unsigned (this_frame, M32R_SP_REGNUM); |
| 241 | sigcontext_addr = cache->base + 4; |
| 242 | |
| 243 | cache->pc = get_frame_pc (this_frame); |
| 244 | addr = m32r_linux_sigtramp_start (cache->pc, this_frame); |
| 245 | if (addr == 0) |
| 246 | { |
| 247 | /* If this is a RT signal trampoline, adjust SIGCONTEXT_ADDR |
| 248 | accordingly. */ |
| 249 | addr = m32r_linux_rt_sigtramp_start (cache->pc, this_frame); |
| 250 | if (addr) |
| 251 | sigcontext_addr += 128; |
| 252 | else |
| 253 | addr = get_frame_func (this_frame); |
| 254 | } |
| 255 | cache->pc = addr; |
| 256 | |
| 257 | cache->saved_regs = trad_frame_alloc_saved_regs (this_frame); |
| 258 | |
| 259 | for (regnum = 0; regnum < sizeof (m32r_linux_sc_reg_offset) / 4; regnum++) |
| 260 | { |
| 261 | if (m32r_linux_sc_reg_offset[regnum] >= 0) |
| 262 | cache->saved_regs[regnum].addr = |
| 263 | sigcontext_addr + m32r_linux_sc_reg_offset[regnum]; |
| 264 | } |
| 265 | |
| 266 | return cache; |
| 267 | } |
| 268 | |
| 269 | static void |
| 270 | m32r_linux_sigtramp_frame_this_id (struct frame_info *this_frame, |
| 271 | void **this_cache, |
| 272 | struct frame_id *this_id) |
| 273 | { |
| 274 | struct m32r_frame_cache *cache = |
| 275 | m32r_linux_sigtramp_frame_cache (this_frame, this_cache); |
| 276 | |
| 277 | (*this_id) = frame_id_build (cache->base, cache->pc); |
| 278 | } |
| 279 | |
| 280 | static struct value * |
| 281 | m32r_linux_sigtramp_frame_prev_register (struct frame_info *this_frame, |
| 282 | void **this_cache, int regnum) |
| 283 | { |
| 284 | struct m32r_frame_cache *cache = |
| 285 | m32r_linux_sigtramp_frame_cache (this_frame, this_cache); |
| 286 | |
| 287 | return trad_frame_get_prev_register (this_frame, cache->saved_regs, regnum); |
| 288 | } |
| 289 | |
| 290 | static int |
| 291 | m32r_linux_sigtramp_frame_sniffer (const struct frame_unwind *self, |
| 292 | struct frame_info *this_frame, |
| 293 | void **this_cache) |
| 294 | { |
| 295 | CORE_ADDR pc = get_frame_pc (this_frame); |
| 296 | const char *name; |
| 297 | |
| 298 | find_pc_partial_function (pc, &name, NULL, NULL); |
| 299 | if (m32r_linux_pc_in_sigtramp (pc, name, this_frame)) |
| 300 | return 1; |
| 301 | |
| 302 | return 0; |
| 303 | } |
| 304 | |
| 305 | static const struct frame_unwind m32r_linux_sigtramp_frame_unwind = { |
| 306 | SIGTRAMP_FRAME, |
| 307 | default_frame_unwind_stop_reason, |
| 308 | m32r_linux_sigtramp_frame_this_id, |
| 309 | m32r_linux_sigtramp_frame_prev_register, |
| 310 | NULL, |
| 311 | m32r_linux_sigtramp_frame_sniffer |
| 312 | }; |
| 313 | |
| 314 | /* Mapping between the registers in `struct pt_regs' |
| 315 | format and GDB's register array layout. */ |
| 316 | |
| 317 | static int m32r_pt_regs_offset[] = { |
| 318 | 4 * 4, /* r0 */ |
| 319 | 4 * 5, /* r1 */ |
| 320 | 4 * 6, /* r2 */ |
| 321 | 4 * 7, /* r3 */ |
| 322 | 4 * 0, /* r4 */ |
| 323 | 4 * 1, /* r5 */ |
| 324 | 4 * 2, /* r6 */ |
| 325 | 4 * 8, /* r7 */ |
| 326 | 4 * 9, /* r8 */ |
| 327 | 4 * 10, /* r9 */ |
| 328 | 4 * 11, /* r10 */ |
| 329 | 4 * 12, /* r11 */ |
| 330 | 4 * 13, /* r12 */ |
| 331 | 4 * 24, /* fp */ |
| 332 | 4 * 25, /* lr */ |
| 333 | 4 * 23, /* sp */ |
| 334 | 4 * 19, /* psw */ |
| 335 | 4 * 19, /* cbr */ |
| 336 | 4 * 26, /* spi */ |
| 337 | 4 * 23, /* spu */ |
| 338 | 4 * 22, /* bpc */ |
| 339 | 4 * 20, /* pc */ |
| 340 | 4 * 16, /* accl */ |
| 341 | 4 * 15 /* acch */ |
| 342 | }; |
| 343 | |
| 344 | #define PSW_OFFSET (4 * 19) |
| 345 | #define BBPSW_OFFSET (4 * 21) |
| 346 | #define SPU_OFFSET (4 * 23) |
| 347 | #define SPI_OFFSET (4 * 26) |
| 348 | |
| 349 | static void |
| 350 | m32r_linux_supply_gregset (const struct regset *regset, |
| 351 | struct regcache *regcache, int regnum, |
| 352 | const void *gregs, size_t size) |
| 353 | { |
| 354 | const char *regs = gregs; |
| 355 | unsigned long psw, bbpsw; |
| 356 | int i; |
| 357 | |
| 358 | psw = *((unsigned long *) (regs + PSW_OFFSET)); |
| 359 | bbpsw = *((unsigned long *) (regs + BBPSW_OFFSET)); |
| 360 | |
| 361 | for (i = 0; i < sizeof (m32r_pt_regs_offset) / 4; i++) |
| 362 | { |
| 363 | if (regnum != -1 && regnum != i) |
| 364 | continue; |
| 365 | |
| 366 | switch (i) |
| 367 | { |
| 368 | case PSW_REGNUM: |
| 369 | *((unsigned long *) (regs + m32r_pt_regs_offset[i])) = |
| 370 | ((0x00c1 & bbpsw) << 8) | ((0xc100 & psw) >> 8); |
| 371 | break; |
| 372 | case CBR_REGNUM: |
| 373 | *((unsigned long *) (regs + m32r_pt_regs_offset[i])) = |
| 374 | ((psw >> 8) & 1); |
| 375 | break; |
| 376 | case M32R_SP_REGNUM: |
| 377 | if (psw & 0x8000) |
| 378 | *((unsigned long *) (regs + m32r_pt_regs_offset[i])) = |
| 379 | *((unsigned long *) (regs + SPU_OFFSET)); |
| 380 | else |
| 381 | *((unsigned long *) (regs + m32r_pt_regs_offset[i])) = |
| 382 | *((unsigned long *) (regs + SPI_OFFSET)); |
| 383 | break; |
| 384 | } |
| 385 | |
| 386 | regcache_raw_supply (regcache, i, |
| 387 | regs + m32r_pt_regs_offset[i]); |
| 388 | } |
| 389 | } |
| 390 | |
| 391 | static struct regset m32r_linux_gregset = { |
| 392 | NULL, m32r_linux_supply_gregset |
| 393 | }; |
| 394 | |
| 395 | static const struct regset * |
| 396 | m32r_linux_regset_from_core_section (struct gdbarch *core_arch, |
| 397 | const char *sect_name, size_t sect_size) |
| 398 | { |
| 399 | struct gdbarch_tdep *tdep = gdbarch_tdep (core_arch); |
| 400 | if (strcmp (sect_name, ".reg") == 0) |
| 401 | return &m32r_linux_gregset; |
| 402 | return NULL; |
| 403 | } |
| 404 | |
| 405 | static void |
| 406 | m32r_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) |
| 407 | { |
| 408 | struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); |
| 409 | |
| 410 | linux_init_abi (info, gdbarch); |
| 411 | |
| 412 | /* Since EVB register is not available for native debug, we reduce |
| 413 | the number of registers. */ |
| 414 | set_gdbarch_num_regs (gdbarch, M32R_NUM_REGS - 1); |
| 415 | |
| 416 | frame_unwind_append_unwinder (gdbarch, &m32r_linux_sigtramp_frame_unwind); |
| 417 | |
| 418 | /* GNU/Linux uses SVR4-style shared libraries. */ |
| 419 | set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target); |
| 420 | set_solib_svr4_fetch_link_map_offsets |
| 421 | (gdbarch, svr4_ilp32_fetch_link_map_offsets); |
| 422 | |
| 423 | /* Core file support. */ |
| 424 | set_gdbarch_regset_from_core_section |
| 425 | (gdbarch, m32r_linux_regset_from_core_section); |
| 426 | |
| 427 | /* Enable TLS support. */ |
| 428 | set_gdbarch_fetch_tls_load_module_address (gdbarch, |
| 429 | svr4_fetch_objfile_link_map); |
| 430 | } |
| 431 | |
| 432 | /* Provide a prototype to silence -Wmissing-prototypes. */ |
| 433 | extern void _initialize_m32r_linux_tdep (void); |
| 434 | |
| 435 | void |
| 436 | _initialize_m32r_linux_tdep (void) |
| 437 | { |
| 438 | gdbarch_register_osabi (bfd_arch_m32r, 0, GDB_OSABI_LINUX, |
| 439 | m32r_linux_init_abi); |
| 440 | } |