| 1 | /* GNU/Linux on ARM target support. |
| 2 | |
| 3 | Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, |
| 4 | 2009 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 "defs.h" |
| 22 | #include "target.h" |
| 23 | #include "value.h" |
| 24 | #include "gdbtypes.h" |
| 25 | #include "floatformat.h" |
| 26 | #include "gdbcore.h" |
| 27 | #include "frame.h" |
| 28 | #include "regcache.h" |
| 29 | #include "doublest.h" |
| 30 | #include "solib-svr4.h" |
| 31 | #include "osabi.h" |
| 32 | #include "regset.h" |
| 33 | #include "trad-frame.h" |
| 34 | #include "tramp-frame.h" |
| 35 | #include "breakpoint.h" |
| 36 | |
| 37 | #include "arm-tdep.h" |
| 38 | #include "arm-linux-tdep.h" |
| 39 | #include "linux-tdep.h" |
| 40 | #include "glibc-tdep.h" |
| 41 | #include "arch-utils.h" |
| 42 | #include "inferior.h" |
| 43 | #include "gdbthread.h" |
| 44 | #include "symfile.h" |
| 45 | |
| 46 | #include "gdb_string.h" |
| 47 | |
| 48 | extern int arm_apcs_32; |
| 49 | |
| 50 | /* Under ARM GNU/Linux the traditional way of performing a breakpoint |
| 51 | is to execute a particular software interrupt, rather than use a |
| 52 | particular undefined instruction to provoke a trap. Upon exection |
| 53 | of the software interrupt the kernel stops the inferior with a |
| 54 | SIGTRAP, and wakes the debugger. */ |
| 55 | |
| 56 | static const char arm_linux_arm_le_breakpoint[] = { 0x01, 0x00, 0x9f, 0xef }; |
| 57 | |
| 58 | static const char arm_linux_arm_be_breakpoint[] = { 0xef, 0x9f, 0x00, 0x01 }; |
| 59 | |
| 60 | /* However, the EABI syscall interface (new in Nov. 2005) does not look at |
| 61 | the operand of the swi if old-ABI compatibility is disabled. Therefore, |
| 62 | use an undefined instruction instead. This is supported as of kernel |
| 63 | version 2.5.70 (May 2003), so should be a safe assumption for EABI |
| 64 | binaries. */ |
| 65 | |
| 66 | static const char eabi_linux_arm_le_breakpoint[] = { 0xf0, 0x01, 0xf0, 0xe7 }; |
| 67 | |
| 68 | static const char eabi_linux_arm_be_breakpoint[] = { 0xe7, 0xf0, 0x01, 0xf0 }; |
| 69 | |
| 70 | /* All the kernels which support Thumb support using a specific undefined |
| 71 | instruction for the Thumb breakpoint. */ |
| 72 | |
| 73 | static const char arm_linux_thumb_be_breakpoint[] = {0xde, 0x01}; |
| 74 | |
| 75 | static const char arm_linux_thumb_le_breakpoint[] = {0x01, 0xde}; |
| 76 | |
| 77 | /* Description of the longjmp buffer. */ |
| 78 | #define ARM_LINUX_JB_ELEMENT_SIZE INT_REGISTER_SIZE |
| 79 | #define ARM_LINUX_JB_PC 21 |
| 80 | |
| 81 | /* |
| 82 | Dynamic Linking on ARM GNU/Linux |
| 83 | -------------------------------- |
| 84 | |
| 85 | Note: PLT = procedure linkage table |
| 86 | GOT = global offset table |
| 87 | |
| 88 | As much as possible, ELF dynamic linking defers the resolution of |
| 89 | jump/call addresses until the last minute. The technique used is |
| 90 | inspired by the i386 ELF design, and is based on the following |
| 91 | constraints. |
| 92 | |
| 93 | 1) The calling technique should not force a change in the assembly |
| 94 | code produced for apps; it MAY cause changes in the way assembly |
| 95 | code is produced for position independent code (i.e. shared |
| 96 | libraries). |
| 97 | |
| 98 | 2) The technique must be such that all executable areas must not be |
| 99 | modified; and any modified areas must not be executed. |
| 100 | |
| 101 | To do this, there are three steps involved in a typical jump: |
| 102 | |
| 103 | 1) in the code |
| 104 | 2) through the PLT |
| 105 | 3) using a pointer from the GOT |
| 106 | |
| 107 | When the executable or library is first loaded, each GOT entry is |
| 108 | initialized to point to the code which implements dynamic name |
| 109 | resolution and code finding. This is normally a function in the |
| 110 | program interpreter (on ARM GNU/Linux this is usually |
| 111 | ld-linux.so.2, but it does not have to be). On the first |
| 112 | invocation, the function is located and the GOT entry is replaced |
| 113 | with the real function address. Subsequent calls go through steps |
| 114 | 1, 2 and 3 and end up calling the real code. |
| 115 | |
| 116 | 1) In the code: |
| 117 | |
| 118 | b function_call |
| 119 | bl function_call |
| 120 | |
| 121 | This is typical ARM code using the 26 bit relative branch or branch |
| 122 | and link instructions. The target of the instruction |
| 123 | (function_call is usually the address of the function to be called. |
| 124 | In position independent code, the target of the instruction is |
| 125 | actually an entry in the PLT when calling functions in a shared |
| 126 | library. Note that this call is identical to a normal function |
| 127 | call, only the target differs. |
| 128 | |
| 129 | 2) In the PLT: |
| 130 | |
| 131 | The PLT is a synthetic area, created by the linker. It exists in |
| 132 | both executables and libraries. It is an array of stubs, one per |
| 133 | imported function call. It looks like this: |
| 134 | |
| 135 | PLT[0]: |
| 136 | str lr, [sp, #-4]! @push the return address (lr) |
| 137 | ldr lr, [pc, #16] @load from 6 words ahead |
| 138 | add lr, pc, lr @form an address for GOT[0] |
| 139 | ldr pc, [lr, #8]! @jump to the contents of that addr |
| 140 | |
| 141 | The return address (lr) is pushed on the stack and used for |
| 142 | calculations. The load on the second line loads the lr with |
| 143 | &GOT[3] - . - 20. The addition on the third leaves: |
| 144 | |
| 145 | lr = (&GOT[3] - . - 20) + (. + 8) |
| 146 | lr = (&GOT[3] - 12) |
| 147 | lr = &GOT[0] |
| 148 | |
| 149 | On the fourth line, the pc and lr are both updated, so that: |
| 150 | |
| 151 | pc = GOT[2] |
| 152 | lr = &GOT[0] + 8 |
| 153 | = &GOT[2] |
| 154 | |
| 155 | NOTE: PLT[0] borrows an offset .word from PLT[1]. This is a little |
| 156 | "tight", but allows us to keep all the PLT entries the same size. |
| 157 | |
| 158 | PLT[n+1]: |
| 159 | ldr ip, [pc, #4] @load offset from gotoff |
| 160 | add ip, pc, ip @add the offset to the pc |
| 161 | ldr pc, [ip] @jump to that address |
| 162 | gotoff: .word GOT[n+3] - . |
| 163 | |
| 164 | The load on the first line, gets an offset from the fourth word of |
| 165 | the PLT entry. The add on the second line makes ip = &GOT[n+3], |
| 166 | which contains either a pointer to PLT[0] (the fixup trampoline) or |
| 167 | a pointer to the actual code. |
| 168 | |
| 169 | 3) In the GOT: |
| 170 | |
| 171 | The GOT contains helper pointers for both code (PLT) fixups and |
| 172 | data fixups. The first 3 entries of the GOT are special. The next |
| 173 | M entries (where M is the number of entries in the PLT) belong to |
| 174 | the PLT fixups. The next D (all remaining) entries belong to |
| 175 | various data fixups. The actual size of the GOT is 3 + M + D. |
| 176 | |
| 177 | The GOT is also a synthetic area, created by the linker. It exists |
| 178 | in both executables and libraries. When the GOT is first |
| 179 | initialized , all the GOT entries relating to PLT fixups are |
| 180 | pointing to code back at PLT[0]. |
| 181 | |
| 182 | The special entries in the GOT are: |
| 183 | |
| 184 | GOT[0] = linked list pointer used by the dynamic loader |
| 185 | GOT[1] = pointer to the reloc table for this module |
| 186 | GOT[2] = pointer to the fixup/resolver code |
| 187 | |
| 188 | The first invocation of function call comes through and uses the |
| 189 | fixup/resolver code. On the entry to the fixup/resolver code: |
| 190 | |
| 191 | ip = &GOT[n+3] |
| 192 | lr = &GOT[2] |
| 193 | stack[0] = return address (lr) of the function call |
| 194 | [r0, r1, r2, r3] are still the arguments to the function call |
| 195 | |
| 196 | This is enough information for the fixup/resolver code to work |
| 197 | with. Before the fixup/resolver code returns, it actually calls |
| 198 | the requested function and repairs &GOT[n+3]. */ |
| 199 | |
| 200 | /* The constants below were determined by examining the following files |
| 201 | in the linux kernel sources: |
| 202 | |
| 203 | arch/arm/kernel/signal.c |
| 204 | - see SWI_SYS_SIGRETURN and SWI_SYS_RT_SIGRETURN |
| 205 | include/asm-arm/unistd.h |
| 206 | - see __NR_sigreturn, __NR_rt_sigreturn, and __NR_SYSCALL_BASE */ |
| 207 | |
| 208 | #define ARM_LINUX_SIGRETURN_INSTR 0xef900077 |
| 209 | #define ARM_LINUX_RT_SIGRETURN_INSTR 0xef9000ad |
| 210 | |
| 211 | /* For ARM EABI, the syscall number is not in the SWI instruction |
| 212 | (instead it is loaded into r7). We recognize the pattern that |
| 213 | glibc uses... alternatively, we could arrange to do this by |
| 214 | function name, but they are not always exported. */ |
| 215 | #define ARM_SET_R7_SIGRETURN 0xe3a07077 |
| 216 | #define ARM_SET_R7_RT_SIGRETURN 0xe3a070ad |
| 217 | #define ARM_EABI_SYSCALL 0xef000000 |
| 218 | |
| 219 | static void |
| 220 | arm_linux_sigtramp_cache (struct frame_info *this_frame, |
| 221 | struct trad_frame_cache *this_cache, |
| 222 | CORE_ADDR func, int regs_offset) |
| 223 | { |
| 224 | CORE_ADDR sp = get_frame_register_unsigned (this_frame, ARM_SP_REGNUM); |
| 225 | CORE_ADDR base = sp + regs_offset; |
| 226 | int i; |
| 227 | |
| 228 | for (i = 0; i < 16; i++) |
| 229 | trad_frame_set_reg_addr (this_cache, i, base + i * 4); |
| 230 | |
| 231 | trad_frame_set_reg_addr (this_cache, ARM_PS_REGNUM, base + 16 * 4); |
| 232 | |
| 233 | /* The VFP or iWMMXt registers may be saved on the stack, but there's |
| 234 | no reliable way to restore them (yet). */ |
| 235 | |
| 236 | /* Save a frame ID. */ |
| 237 | trad_frame_set_id (this_cache, frame_id_build (sp, func)); |
| 238 | } |
| 239 | |
| 240 | /* There are a couple of different possible stack layouts that |
| 241 | we need to support. |
| 242 | |
| 243 | Before version 2.6.18, the kernel used completely independent |
| 244 | layouts for non-RT and RT signals. For non-RT signals the stack |
| 245 | began directly with a struct sigcontext. For RT signals the stack |
| 246 | began with two redundant pointers (to the siginfo and ucontext), |
| 247 | and then the siginfo and ucontext. |
| 248 | |
| 249 | As of version 2.6.18, the non-RT signal frame layout starts with |
| 250 | a ucontext and the RT signal frame starts with a siginfo and then |
| 251 | a ucontext. Also, the ucontext now has a designated save area |
| 252 | for coprocessor registers. |
| 253 | |
| 254 | For RT signals, it's easy to tell the difference: we look for |
| 255 | pinfo, the pointer to the siginfo. If it has the expected |
| 256 | value, we have an old layout. If it doesn't, we have the new |
| 257 | layout. |
| 258 | |
| 259 | For non-RT signals, it's a bit harder. We need something in one |
| 260 | layout or the other with a recognizable offset and value. We can't |
| 261 | use the return trampoline, because ARM usually uses SA_RESTORER, |
| 262 | in which case the stack return trampoline is not filled in. |
| 263 | We can't use the saved stack pointer, because sigaltstack might |
| 264 | be in use. So for now we guess the new layout... */ |
| 265 | |
| 266 | /* There are three words (trap_no, error_code, oldmask) in |
| 267 | struct sigcontext before r0. */ |
| 268 | #define ARM_SIGCONTEXT_R0 0xc |
| 269 | |
| 270 | /* There are five words (uc_flags, uc_link, and three for uc_stack) |
| 271 | in the ucontext_t before the sigcontext. */ |
| 272 | #define ARM_UCONTEXT_SIGCONTEXT 0x14 |
| 273 | |
| 274 | /* There are three elements in an rt_sigframe before the ucontext: |
| 275 | pinfo, puc, and info. The first two are pointers and the third |
| 276 | is a struct siginfo, with size 128 bytes. We could follow puc |
| 277 | to the ucontext, but it's simpler to skip the whole thing. */ |
| 278 | #define ARM_OLD_RT_SIGFRAME_SIGINFO 0x8 |
| 279 | #define ARM_OLD_RT_SIGFRAME_UCONTEXT 0x88 |
| 280 | |
| 281 | #define ARM_NEW_RT_SIGFRAME_UCONTEXT 0x80 |
| 282 | |
| 283 | #define ARM_NEW_SIGFRAME_MAGIC 0x5ac3c35a |
| 284 | |
| 285 | static void |
| 286 | arm_linux_sigreturn_init (const struct tramp_frame *self, |
| 287 | struct frame_info *this_frame, |
| 288 | struct trad_frame_cache *this_cache, |
| 289 | CORE_ADDR func) |
| 290 | { |
| 291 | struct gdbarch *gdbarch = get_frame_arch (this_frame); |
| 292 | enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); |
| 293 | CORE_ADDR sp = get_frame_register_unsigned (this_frame, ARM_SP_REGNUM); |
| 294 | ULONGEST uc_flags = read_memory_unsigned_integer (sp, 4, byte_order); |
| 295 | |
| 296 | if (uc_flags == ARM_NEW_SIGFRAME_MAGIC) |
| 297 | arm_linux_sigtramp_cache (this_frame, this_cache, func, |
| 298 | ARM_UCONTEXT_SIGCONTEXT |
| 299 | + ARM_SIGCONTEXT_R0); |
| 300 | else |
| 301 | arm_linux_sigtramp_cache (this_frame, this_cache, func, |
| 302 | ARM_SIGCONTEXT_R0); |
| 303 | } |
| 304 | |
| 305 | static void |
| 306 | arm_linux_rt_sigreturn_init (const struct tramp_frame *self, |
| 307 | struct frame_info *this_frame, |
| 308 | struct trad_frame_cache *this_cache, |
| 309 | CORE_ADDR func) |
| 310 | { |
| 311 | struct gdbarch *gdbarch = get_frame_arch (this_frame); |
| 312 | enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); |
| 313 | CORE_ADDR sp = get_frame_register_unsigned (this_frame, ARM_SP_REGNUM); |
| 314 | ULONGEST pinfo = read_memory_unsigned_integer (sp, 4, byte_order); |
| 315 | |
| 316 | if (pinfo == sp + ARM_OLD_RT_SIGFRAME_SIGINFO) |
| 317 | arm_linux_sigtramp_cache (this_frame, this_cache, func, |
| 318 | ARM_OLD_RT_SIGFRAME_UCONTEXT |
| 319 | + ARM_UCONTEXT_SIGCONTEXT |
| 320 | + ARM_SIGCONTEXT_R0); |
| 321 | else |
| 322 | arm_linux_sigtramp_cache (this_frame, this_cache, func, |
| 323 | ARM_NEW_RT_SIGFRAME_UCONTEXT |
| 324 | + ARM_UCONTEXT_SIGCONTEXT |
| 325 | + ARM_SIGCONTEXT_R0); |
| 326 | } |
| 327 | |
| 328 | static struct tramp_frame arm_linux_sigreturn_tramp_frame = { |
| 329 | SIGTRAMP_FRAME, |
| 330 | 4, |
| 331 | { |
| 332 | { ARM_LINUX_SIGRETURN_INSTR, -1 }, |
| 333 | { TRAMP_SENTINEL_INSN } |
| 334 | }, |
| 335 | arm_linux_sigreturn_init |
| 336 | }; |
| 337 | |
| 338 | static struct tramp_frame arm_linux_rt_sigreturn_tramp_frame = { |
| 339 | SIGTRAMP_FRAME, |
| 340 | 4, |
| 341 | { |
| 342 | { ARM_LINUX_RT_SIGRETURN_INSTR, -1 }, |
| 343 | { TRAMP_SENTINEL_INSN } |
| 344 | }, |
| 345 | arm_linux_rt_sigreturn_init |
| 346 | }; |
| 347 | |
| 348 | static struct tramp_frame arm_eabi_linux_sigreturn_tramp_frame = { |
| 349 | SIGTRAMP_FRAME, |
| 350 | 4, |
| 351 | { |
| 352 | { ARM_SET_R7_SIGRETURN, -1 }, |
| 353 | { ARM_EABI_SYSCALL, -1 }, |
| 354 | { TRAMP_SENTINEL_INSN } |
| 355 | }, |
| 356 | arm_linux_sigreturn_init |
| 357 | }; |
| 358 | |
| 359 | static struct tramp_frame arm_eabi_linux_rt_sigreturn_tramp_frame = { |
| 360 | SIGTRAMP_FRAME, |
| 361 | 4, |
| 362 | { |
| 363 | { ARM_SET_R7_RT_SIGRETURN, -1 }, |
| 364 | { ARM_EABI_SYSCALL, -1 }, |
| 365 | { TRAMP_SENTINEL_INSN } |
| 366 | }, |
| 367 | arm_linux_rt_sigreturn_init |
| 368 | }; |
| 369 | |
| 370 | /* Core file and register set support. */ |
| 371 | |
| 372 | #define ARM_LINUX_SIZEOF_GREGSET (18 * INT_REGISTER_SIZE) |
| 373 | |
| 374 | void |
| 375 | arm_linux_supply_gregset (const struct regset *regset, |
| 376 | struct regcache *regcache, |
| 377 | int regnum, const void *gregs_buf, size_t len) |
| 378 | { |
| 379 | struct gdbarch *gdbarch = get_regcache_arch (regcache); |
| 380 | enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); |
| 381 | const gdb_byte *gregs = gregs_buf; |
| 382 | int regno; |
| 383 | CORE_ADDR reg_pc; |
| 384 | gdb_byte pc_buf[INT_REGISTER_SIZE]; |
| 385 | |
| 386 | for (regno = ARM_A1_REGNUM; regno < ARM_PC_REGNUM; regno++) |
| 387 | if (regnum == -1 || regnum == regno) |
| 388 | regcache_raw_supply (regcache, regno, |
| 389 | gregs + INT_REGISTER_SIZE * regno); |
| 390 | |
| 391 | if (regnum == ARM_PS_REGNUM || regnum == -1) |
| 392 | { |
| 393 | if (arm_apcs_32) |
| 394 | regcache_raw_supply (regcache, ARM_PS_REGNUM, |
| 395 | gregs + INT_REGISTER_SIZE * ARM_CPSR_GREGNUM); |
| 396 | else |
| 397 | regcache_raw_supply (regcache, ARM_PS_REGNUM, |
| 398 | gregs + INT_REGISTER_SIZE * ARM_PC_REGNUM); |
| 399 | } |
| 400 | |
| 401 | if (regnum == ARM_PC_REGNUM || regnum == -1) |
| 402 | { |
| 403 | reg_pc = extract_unsigned_integer (gregs |
| 404 | + INT_REGISTER_SIZE * ARM_PC_REGNUM, |
| 405 | INT_REGISTER_SIZE, byte_order); |
| 406 | reg_pc = gdbarch_addr_bits_remove (gdbarch, reg_pc); |
| 407 | store_unsigned_integer (pc_buf, INT_REGISTER_SIZE, byte_order, reg_pc); |
| 408 | regcache_raw_supply (regcache, ARM_PC_REGNUM, pc_buf); |
| 409 | } |
| 410 | } |
| 411 | |
| 412 | void |
| 413 | arm_linux_collect_gregset (const struct regset *regset, |
| 414 | const struct regcache *regcache, |
| 415 | int regnum, void *gregs_buf, size_t len) |
| 416 | { |
| 417 | gdb_byte *gregs = gregs_buf; |
| 418 | int regno; |
| 419 | |
| 420 | for (regno = ARM_A1_REGNUM; regno < ARM_PC_REGNUM; regno++) |
| 421 | if (regnum == -1 || regnum == regno) |
| 422 | regcache_raw_collect (regcache, regno, |
| 423 | gregs + INT_REGISTER_SIZE * regno); |
| 424 | |
| 425 | if (regnum == ARM_PS_REGNUM || regnum == -1) |
| 426 | { |
| 427 | if (arm_apcs_32) |
| 428 | regcache_raw_collect (regcache, ARM_PS_REGNUM, |
| 429 | gregs + INT_REGISTER_SIZE * ARM_CPSR_GREGNUM); |
| 430 | else |
| 431 | regcache_raw_collect (regcache, ARM_PS_REGNUM, |
| 432 | gregs + INT_REGISTER_SIZE * ARM_PC_REGNUM); |
| 433 | } |
| 434 | |
| 435 | if (regnum == ARM_PC_REGNUM || regnum == -1) |
| 436 | regcache_raw_collect (regcache, ARM_PC_REGNUM, |
| 437 | gregs + INT_REGISTER_SIZE * ARM_PC_REGNUM); |
| 438 | } |
| 439 | |
| 440 | /* Support for register format used by the NWFPE FPA emulator. */ |
| 441 | |
| 442 | #define typeNone 0x00 |
| 443 | #define typeSingle 0x01 |
| 444 | #define typeDouble 0x02 |
| 445 | #define typeExtended 0x03 |
| 446 | |
| 447 | void |
| 448 | supply_nwfpe_register (struct regcache *regcache, int regno, |
| 449 | const gdb_byte *regs) |
| 450 | { |
| 451 | const gdb_byte *reg_data; |
| 452 | gdb_byte reg_tag; |
| 453 | gdb_byte buf[FP_REGISTER_SIZE]; |
| 454 | |
| 455 | reg_data = regs + (regno - ARM_F0_REGNUM) * FP_REGISTER_SIZE; |
| 456 | reg_tag = regs[(regno - ARM_F0_REGNUM) + NWFPE_TAGS_OFFSET]; |
| 457 | memset (buf, 0, FP_REGISTER_SIZE); |
| 458 | |
| 459 | switch (reg_tag) |
| 460 | { |
| 461 | case typeSingle: |
| 462 | memcpy (buf, reg_data, 4); |
| 463 | break; |
| 464 | case typeDouble: |
| 465 | memcpy (buf, reg_data + 4, 4); |
| 466 | memcpy (buf + 4, reg_data, 4); |
| 467 | break; |
| 468 | case typeExtended: |
| 469 | /* We want sign and exponent, then least significant bits, |
| 470 | then most significant. NWFPE does sign, most, least. */ |
| 471 | memcpy (buf, reg_data, 4); |
| 472 | memcpy (buf + 4, reg_data + 8, 4); |
| 473 | memcpy (buf + 8, reg_data + 4, 4); |
| 474 | break; |
| 475 | default: |
| 476 | break; |
| 477 | } |
| 478 | |
| 479 | regcache_raw_supply (regcache, regno, buf); |
| 480 | } |
| 481 | |
| 482 | void |
| 483 | collect_nwfpe_register (const struct regcache *regcache, int regno, |
| 484 | gdb_byte *regs) |
| 485 | { |
| 486 | gdb_byte *reg_data; |
| 487 | gdb_byte reg_tag; |
| 488 | gdb_byte buf[FP_REGISTER_SIZE]; |
| 489 | |
| 490 | regcache_raw_collect (regcache, regno, buf); |
| 491 | |
| 492 | /* NOTE drow/2006-06-07: This code uses the tag already in the |
| 493 | register buffer. I've preserved that when moving the code |
| 494 | from the native file to the target file. But this doesn't |
| 495 | always make sense. */ |
| 496 | |
| 497 | reg_data = regs + (regno - ARM_F0_REGNUM) * FP_REGISTER_SIZE; |
| 498 | reg_tag = regs[(regno - ARM_F0_REGNUM) + NWFPE_TAGS_OFFSET]; |
| 499 | |
| 500 | switch (reg_tag) |
| 501 | { |
| 502 | case typeSingle: |
| 503 | memcpy (reg_data, buf, 4); |
| 504 | break; |
| 505 | case typeDouble: |
| 506 | memcpy (reg_data, buf + 4, 4); |
| 507 | memcpy (reg_data + 4, buf, 4); |
| 508 | break; |
| 509 | case typeExtended: |
| 510 | memcpy (reg_data, buf, 4); |
| 511 | memcpy (reg_data + 4, buf + 8, 4); |
| 512 | memcpy (reg_data + 8, buf + 4, 4); |
| 513 | break; |
| 514 | default: |
| 515 | break; |
| 516 | } |
| 517 | } |
| 518 | |
| 519 | void |
| 520 | arm_linux_supply_nwfpe (const struct regset *regset, |
| 521 | struct regcache *regcache, |
| 522 | int regnum, const void *regs_buf, size_t len) |
| 523 | { |
| 524 | const gdb_byte *regs = regs_buf; |
| 525 | int regno; |
| 526 | |
| 527 | if (regnum == ARM_FPS_REGNUM || regnum == -1) |
| 528 | regcache_raw_supply (regcache, ARM_FPS_REGNUM, |
| 529 | regs + NWFPE_FPSR_OFFSET); |
| 530 | |
| 531 | for (regno = ARM_F0_REGNUM; regno <= ARM_F7_REGNUM; regno++) |
| 532 | if (regnum == -1 || regnum == regno) |
| 533 | supply_nwfpe_register (regcache, regno, regs); |
| 534 | } |
| 535 | |
| 536 | void |
| 537 | arm_linux_collect_nwfpe (const struct regset *regset, |
| 538 | const struct regcache *regcache, |
| 539 | int regnum, void *regs_buf, size_t len) |
| 540 | { |
| 541 | gdb_byte *regs = regs_buf; |
| 542 | int regno; |
| 543 | |
| 544 | for (regno = ARM_F0_REGNUM; regno <= ARM_F7_REGNUM; regno++) |
| 545 | if (regnum == -1 || regnum == regno) |
| 546 | collect_nwfpe_register (regcache, regno, regs); |
| 547 | |
| 548 | if (regnum == ARM_FPS_REGNUM || regnum == -1) |
| 549 | regcache_raw_collect (regcache, ARM_FPS_REGNUM, |
| 550 | regs + INT_REGISTER_SIZE * ARM_FPS_REGNUM); |
| 551 | } |
| 552 | |
| 553 | /* Return the appropriate register set for the core section identified |
| 554 | by SECT_NAME and SECT_SIZE. */ |
| 555 | |
| 556 | static const struct regset * |
| 557 | arm_linux_regset_from_core_section (struct gdbarch *gdbarch, |
| 558 | const char *sect_name, size_t sect_size) |
| 559 | { |
| 560 | struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); |
| 561 | |
| 562 | if (strcmp (sect_name, ".reg") == 0 |
| 563 | && sect_size == ARM_LINUX_SIZEOF_GREGSET) |
| 564 | { |
| 565 | if (tdep->gregset == NULL) |
| 566 | tdep->gregset = regset_alloc (gdbarch, arm_linux_supply_gregset, |
| 567 | arm_linux_collect_gregset); |
| 568 | return tdep->gregset; |
| 569 | } |
| 570 | |
| 571 | if (strcmp (sect_name, ".reg2") == 0 |
| 572 | && sect_size == ARM_LINUX_SIZEOF_NWFPE) |
| 573 | { |
| 574 | if (tdep->fpregset == NULL) |
| 575 | tdep->fpregset = regset_alloc (gdbarch, arm_linux_supply_nwfpe, |
| 576 | arm_linux_collect_nwfpe); |
| 577 | return tdep->fpregset; |
| 578 | } |
| 579 | |
| 580 | return NULL; |
| 581 | } |
| 582 | |
| 583 | /* Insert a single step breakpoint at the next executed instruction. */ |
| 584 | |
| 585 | static int |
| 586 | arm_linux_software_single_step (struct frame_info *frame) |
| 587 | { |
| 588 | struct gdbarch *gdbarch = get_frame_arch (frame); |
| 589 | struct address_space *aspace = get_frame_address_space (frame); |
| 590 | CORE_ADDR next_pc = arm_get_next_pc (frame, get_frame_pc (frame)); |
| 591 | |
| 592 | /* The Linux kernel offers some user-mode helpers in a high page. We can |
| 593 | not read this page (as of 2.6.23), and even if we could then we couldn't |
| 594 | set breakpoints in it, and even if we could then the atomic operations |
| 595 | would fail when interrupted. They are all called as functions and return |
| 596 | to the address in LR, so step to there instead. */ |
| 597 | if (next_pc > 0xffff0000) |
| 598 | next_pc = get_frame_register_unsigned (frame, ARM_LR_REGNUM); |
| 599 | |
| 600 | insert_single_step_breakpoint (gdbarch, aspace, next_pc); |
| 601 | |
| 602 | return 1; |
| 603 | } |
| 604 | |
| 605 | /* Support for displaced stepping of Linux SVC instructions. */ |
| 606 | |
| 607 | static void |
| 608 | arm_linux_cleanup_svc (struct gdbarch *gdbarch ATTRIBUTE_UNUSED, |
| 609 | struct regcache *regs, |
| 610 | struct displaced_step_closure *dsc) |
| 611 | { |
| 612 | CORE_ADDR from = dsc->insn_addr; |
| 613 | ULONGEST apparent_pc; |
| 614 | int within_scratch; |
| 615 | |
| 616 | regcache_cooked_read_unsigned (regs, ARM_PC_REGNUM, &apparent_pc); |
| 617 | |
| 618 | within_scratch = (apparent_pc >= dsc->scratch_base |
| 619 | && apparent_pc < (dsc->scratch_base |
| 620 | + DISPLACED_MODIFIED_INSNS * 4 + 4)); |
| 621 | |
| 622 | if (debug_displaced) |
| 623 | { |
| 624 | fprintf_unfiltered (gdb_stdlog, "displaced: PC is apparently %.8lx after " |
| 625 | "SVC step ", (unsigned long) apparent_pc); |
| 626 | if (within_scratch) |
| 627 | fprintf_unfiltered (gdb_stdlog, "(within scratch space)\n"); |
| 628 | else |
| 629 | fprintf_unfiltered (gdb_stdlog, "(outside scratch space)\n"); |
| 630 | } |
| 631 | |
| 632 | if (within_scratch) |
| 633 | displaced_write_reg (regs, dsc, ARM_PC_REGNUM, from + 4, BRANCH_WRITE_PC); |
| 634 | } |
| 635 | |
| 636 | static int |
| 637 | arm_linux_copy_svc (struct gdbarch *gdbarch, uint32_t insn, CORE_ADDR to, |
| 638 | struct regcache *regs, struct displaced_step_closure *dsc) |
| 639 | { |
| 640 | CORE_ADDR from = dsc->insn_addr; |
| 641 | struct frame_info *frame; |
| 642 | unsigned int svc_number = displaced_read_reg (regs, from, 7); |
| 643 | |
| 644 | if (debug_displaced) |
| 645 | fprintf_unfiltered (gdb_stdlog, "displaced: copying Linux svc insn %.8lx\n", |
| 646 | (unsigned long) insn); |
| 647 | |
| 648 | frame = get_current_frame (); |
| 649 | |
| 650 | /* Is this a sigreturn or rt_sigreturn syscall? Note: these are only useful |
| 651 | for EABI. */ |
| 652 | if (svc_number == 119 || svc_number == 173) |
| 653 | { |
| 654 | if (get_frame_type (frame) == SIGTRAMP_FRAME) |
| 655 | { |
| 656 | CORE_ADDR return_to; |
| 657 | struct symtab_and_line sal; |
| 658 | |
| 659 | if (debug_displaced) |
| 660 | fprintf_unfiltered (gdb_stdlog, "displaced: found " |
| 661 | "sigreturn/rt_sigreturn SVC call. PC in frame = %lx\n", |
| 662 | (unsigned long) get_frame_pc (frame)); |
| 663 | |
| 664 | return_to = frame_unwind_caller_pc (frame); |
| 665 | if (debug_displaced) |
| 666 | fprintf_unfiltered (gdb_stdlog, "displaced: unwind pc = %lx. " |
| 667 | "Setting momentary breakpoint.\n", (unsigned long) return_to); |
| 668 | |
| 669 | gdb_assert (inferior_thread ()->step_resume_breakpoint == NULL); |
| 670 | |
| 671 | sal = find_pc_line (return_to, 0); |
| 672 | sal.pc = return_to; |
| 673 | sal.section = find_pc_overlay (return_to); |
| 674 | sal.explicit_pc = 1; |
| 675 | |
| 676 | frame = get_prev_frame (frame); |
| 677 | |
| 678 | if (frame) |
| 679 | { |
| 680 | inferior_thread ()->step_resume_breakpoint |
| 681 | = set_momentary_breakpoint (gdbarch, sal, get_frame_id (frame), |
| 682 | bp_step_resume); |
| 683 | |
| 684 | /* We need to make sure we actually insert the momentary |
| 685 | breakpoint set above. */ |
| 686 | insert_breakpoints (); |
| 687 | } |
| 688 | else if (debug_displaced) |
| 689 | fprintf_unfiltered (gdb_stderr, "displaced: couldn't find previous " |
| 690 | "frame to set momentary breakpoint for " |
| 691 | "sigreturn/rt_sigreturn\n"); |
| 692 | } |
| 693 | else if (debug_displaced) |
| 694 | fprintf_unfiltered (gdb_stdlog, "displaced: sigreturn/rt_sigreturn " |
| 695 | "SVC call not in signal trampoline frame\n"); |
| 696 | } |
| 697 | |
| 698 | /* Preparation: If we detect sigreturn, set momentary breakpoint at resume |
| 699 | location, else nothing. |
| 700 | Insn: unmodified svc. |
| 701 | Cleanup: if pc lands in scratch space, pc <- insn_addr + 4 |
| 702 | else leave pc alone. */ |
| 703 | |
| 704 | dsc->modinsn[0] = insn; |
| 705 | |
| 706 | dsc->cleanup = &arm_linux_cleanup_svc; |
| 707 | /* Pretend we wrote to the PC, so cleanup doesn't set PC to the next |
| 708 | instruction. */ |
| 709 | dsc->wrote_to_pc = 1; |
| 710 | |
| 711 | return 0; |
| 712 | } |
| 713 | |
| 714 | |
| 715 | /* The following two functions implement single-stepping over calls to Linux |
| 716 | kernel helper routines, which perform e.g. atomic operations on architecture |
| 717 | variants which don't support them natively. |
| 718 | |
| 719 | When this function is called, the PC will be pointing at the kernel helper |
| 720 | (at an address inaccessible to GDB), and r14 will point to the return |
| 721 | address. Displaced stepping always executes code in the copy area: |
| 722 | so, make the copy-area instruction branch back to the kernel helper (the |
| 723 | "from" address), and make r14 point to the breakpoint in the copy area. In |
| 724 | that way, we regain control once the kernel helper returns, and can clean |
| 725 | up appropriately (as if we had just returned from the kernel helper as it |
| 726 | would have been called from the non-displaced location). */ |
| 727 | |
| 728 | static void |
| 729 | cleanup_kernel_helper_return (struct gdbarch *gdbarch ATTRIBUTE_UNUSED, |
| 730 | struct regcache *regs, |
| 731 | struct displaced_step_closure *dsc) |
| 732 | { |
| 733 | displaced_write_reg (regs, dsc, ARM_LR_REGNUM, dsc->tmp[0], CANNOT_WRITE_PC); |
| 734 | displaced_write_reg (regs, dsc, ARM_PC_REGNUM, dsc->tmp[0], BRANCH_WRITE_PC); |
| 735 | } |
| 736 | |
| 737 | static void |
| 738 | arm_catch_kernel_helper_return (struct gdbarch *gdbarch, CORE_ADDR from, |
| 739 | CORE_ADDR to, struct regcache *regs, |
| 740 | struct displaced_step_closure *dsc) |
| 741 | { |
| 742 | enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); |
| 743 | |
| 744 | dsc->numinsns = 1; |
| 745 | dsc->insn_addr = from; |
| 746 | dsc->cleanup = &cleanup_kernel_helper_return; |
| 747 | /* Say we wrote to the PC, else cleanup will set PC to the next |
| 748 | instruction in the helper, which isn't helpful. */ |
| 749 | dsc->wrote_to_pc = 1; |
| 750 | |
| 751 | /* Preparation: tmp[0] <- r14 |
| 752 | r14 <- <scratch space>+4 |
| 753 | *(<scratch space>+8) <- from |
| 754 | Insn: ldr pc, [r14, #4] |
| 755 | Cleanup: r14 <- tmp[0], pc <- tmp[0]. */ |
| 756 | |
| 757 | dsc->tmp[0] = displaced_read_reg (regs, from, ARM_LR_REGNUM); |
| 758 | displaced_write_reg (regs, dsc, ARM_LR_REGNUM, (ULONGEST) to + 4, |
| 759 | CANNOT_WRITE_PC); |
| 760 | write_memory_unsigned_integer (to + 8, 4, byte_order, from); |
| 761 | |
| 762 | dsc->modinsn[0] = 0xe59ef004; /* ldr pc, [lr, #4]. */ |
| 763 | } |
| 764 | |
| 765 | /* Linux-specific displaced step instruction copying function. Detects when |
| 766 | the program has stepped into a Linux kernel helper routine (which must be |
| 767 | handled as a special case), falling back to arm_displaced_step_copy_insn() |
| 768 | if it hasn't. */ |
| 769 | |
| 770 | static struct displaced_step_closure * |
| 771 | arm_linux_displaced_step_copy_insn (struct gdbarch *gdbarch, |
| 772 | CORE_ADDR from, CORE_ADDR to, |
| 773 | struct regcache *regs) |
| 774 | { |
| 775 | struct displaced_step_closure *dsc |
| 776 | = xmalloc (sizeof (struct displaced_step_closure)); |
| 777 | |
| 778 | /* Detect when we enter an (inaccessible by GDB) Linux kernel helper, and |
| 779 | stop at the return location. */ |
| 780 | if (from > 0xffff0000) |
| 781 | { |
| 782 | if (debug_displaced) |
| 783 | fprintf_unfiltered (gdb_stdlog, "displaced: detected kernel helper " |
| 784 | "at %.8lx\n", (unsigned long) from); |
| 785 | |
| 786 | arm_catch_kernel_helper_return (gdbarch, from, to, regs, dsc); |
| 787 | } |
| 788 | else |
| 789 | { |
| 790 | enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); |
| 791 | uint32_t insn = read_memory_unsigned_integer (from, 4, byte_order); |
| 792 | |
| 793 | if (debug_displaced) |
| 794 | fprintf_unfiltered (gdb_stdlog, "displaced: stepping insn %.8lx " |
| 795 | "at %.8lx\n", (unsigned long) insn, |
| 796 | (unsigned long) from); |
| 797 | |
| 798 | /* Override the default handling of SVC instructions. */ |
| 799 | dsc->u.svc.copy_svc_os = arm_linux_copy_svc; |
| 800 | |
| 801 | arm_process_displaced_insn (gdbarch, insn, from, to, regs, dsc); |
| 802 | } |
| 803 | |
| 804 | arm_displaced_init_closure (gdbarch, from, to, dsc); |
| 805 | |
| 806 | return dsc; |
| 807 | } |
| 808 | |
| 809 | static void |
| 810 | arm_linux_init_abi (struct gdbarch_info info, |
| 811 | struct gdbarch *gdbarch) |
| 812 | { |
| 813 | struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); |
| 814 | |
| 815 | tdep->lowest_pc = 0x8000; |
| 816 | if (info.byte_order == BFD_ENDIAN_BIG) |
| 817 | { |
| 818 | if (tdep->arm_abi == ARM_ABI_AAPCS) |
| 819 | tdep->arm_breakpoint = eabi_linux_arm_be_breakpoint; |
| 820 | else |
| 821 | tdep->arm_breakpoint = arm_linux_arm_be_breakpoint; |
| 822 | tdep->thumb_breakpoint = arm_linux_thumb_be_breakpoint; |
| 823 | } |
| 824 | else |
| 825 | { |
| 826 | if (tdep->arm_abi == ARM_ABI_AAPCS) |
| 827 | tdep->arm_breakpoint = eabi_linux_arm_le_breakpoint; |
| 828 | else |
| 829 | tdep->arm_breakpoint = arm_linux_arm_le_breakpoint; |
| 830 | tdep->thumb_breakpoint = arm_linux_thumb_le_breakpoint; |
| 831 | } |
| 832 | tdep->arm_breakpoint_size = sizeof (arm_linux_arm_le_breakpoint); |
| 833 | tdep->thumb_breakpoint_size = sizeof (arm_linux_thumb_le_breakpoint); |
| 834 | |
| 835 | if (tdep->fp_model == ARM_FLOAT_AUTO) |
| 836 | tdep->fp_model = ARM_FLOAT_FPA; |
| 837 | |
| 838 | tdep->jb_pc = ARM_LINUX_JB_PC; |
| 839 | tdep->jb_elt_size = ARM_LINUX_JB_ELEMENT_SIZE; |
| 840 | |
| 841 | set_solib_svr4_fetch_link_map_offsets |
| 842 | (gdbarch, svr4_ilp32_fetch_link_map_offsets); |
| 843 | |
| 844 | /* Single stepping. */ |
| 845 | set_gdbarch_software_single_step (gdbarch, arm_linux_software_single_step); |
| 846 | |
| 847 | /* Shared library handling. */ |
| 848 | set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target); |
| 849 | set_gdbarch_skip_solib_resolver (gdbarch, glibc_skip_solib_resolver); |
| 850 | |
| 851 | /* Enable TLS support. */ |
| 852 | set_gdbarch_fetch_tls_load_module_address (gdbarch, |
| 853 | svr4_fetch_objfile_link_map); |
| 854 | |
| 855 | tramp_frame_prepend_unwinder (gdbarch, |
| 856 | &arm_linux_sigreturn_tramp_frame); |
| 857 | tramp_frame_prepend_unwinder (gdbarch, |
| 858 | &arm_linux_rt_sigreturn_tramp_frame); |
| 859 | tramp_frame_prepend_unwinder (gdbarch, |
| 860 | &arm_eabi_linux_sigreturn_tramp_frame); |
| 861 | tramp_frame_prepend_unwinder (gdbarch, |
| 862 | &arm_eabi_linux_rt_sigreturn_tramp_frame); |
| 863 | |
| 864 | /* Core file support. */ |
| 865 | set_gdbarch_regset_from_core_section (gdbarch, |
| 866 | arm_linux_regset_from_core_section); |
| 867 | |
| 868 | set_gdbarch_get_siginfo_type (gdbarch, linux_get_siginfo_type); |
| 869 | |
| 870 | /* Displaced stepping. */ |
| 871 | set_gdbarch_displaced_step_copy_insn (gdbarch, |
| 872 | arm_linux_displaced_step_copy_insn); |
| 873 | set_gdbarch_displaced_step_fixup (gdbarch, arm_displaced_step_fixup); |
| 874 | set_gdbarch_displaced_step_free_closure (gdbarch, |
| 875 | simple_displaced_step_free_closure); |
| 876 | set_gdbarch_displaced_step_location (gdbarch, displaced_step_at_entry_point); |
| 877 | } |
| 878 | |
| 879 | /* Provide a prototype to silence -Wmissing-prototypes. */ |
| 880 | extern initialize_file_ftype _initialize_arm_linux_tdep; |
| 881 | |
| 882 | void |
| 883 | _initialize_arm_linux_tdep (void) |
| 884 | { |
| 885 | gdbarch_register_osabi (bfd_arch_arm, 0, GDB_OSABI_LINUX, |
| 886 | arm_linux_init_abi); |
| 887 | } |