| 1 | /* Native-dependent code for the i386. |
| 2 | |
| 3 | Copyright (C) 2001-2013 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 "i386-nat.h" |
| 22 | #include "breakpoint.h" |
| 23 | #include "command.h" |
| 24 | #include "gdbcmd.h" |
| 25 | #include "target.h" |
| 26 | #include "gdb_assert.h" |
| 27 | #include "inferior.h" |
| 28 | |
| 29 | /* Support for hardware watchpoints and breakpoints using the i386 |
| 30 | debug registers. |
| 31 | |
| 32 | This provides several functions for inserting and removing |
| 33 | hardware-assisted breakpoints and watchpoints, testing if one or |
| 34 | more of the watchpoints triggered and at what address, checking |
| 35 | whether a given region can be watched, etc. |
| 36 | |
| 37 | The functions below implement debug registers sharing by reference |
| 38 | counts, and allow to watch regions up to 16 bytes long. */ |
| 39 | |
| 40 | struct i386_dr_low_type i386_dr_low; |
| 41 | |
| 42 | |
| 43 | /* Support for 8-byte wide hw watchpoints. */ |
| 44 | #define TARGET_HAS_DR_LEN_8 (i386_dr_low.debug_register_length == 8) |
| 45 | |
| 46 | /* DR7 Debug Control register fields. */ |
| 47 | |
| 48 | /* How many bits to skip in DR7 to get to R/W and LEN fields. */ |
| 49 | #define DR_CONTROL_SHIFT 16 |
| 50 | /* How many bits in DR7 per R/W and LEN field for each watchpoint. */ |
| 51 | #define DR_CONTROL_SIZE 4 |
| 52 | |
| 53 | /* Watchpoint/breakpoint read/write fields in DR7. */ |
| 54 | #define DR_RW_EXECUTE (0x0) /* Break on instruction execution. */ |
| 55 | #define DR_RW_WRITE (0x1) /* Break on data writes. */ |
| 56 | #define DR_RW_READ (0x3) /* Break on data reads or writes. */ |
| 57 | |
| 58 | /* This is here for completeness. No platform supports this |
| 59 | functionality yet (as of March 2001). Note that the DE flag in the |
| 60 | CR4 register needs to be set to support this. */ |
| 61 | #ifndef DR_RW_IORW |
| 62 | #define DR_RW_IORW (0x2) /* Break on I/O reads or writes. */ |
| 63 | #endif |
| 64 | |
| 65 | /* Watchpoint/breakpoint length fields in DR7. The 2-bit left shift |
| 66 | is so we could OR this with the read/write field defined above. */ |
| 67 | #define DR_LEN_1 (0x0 << 2) /* 1-byte region watch or breakpoint. */ |
| 68 | #define DR_LEN_2 (0x1 << 2) /* 2-byte region watch. */ |
| 69 | #define DR_LEN_4 (0x3 << 2) /* 4-byte region watch. */ |
| 70 | #define DR_LEN_8 (0x2 << 2) /* 8-byte region watch (AMD64). */ |
| 71 | |
| 72 | /* Local and Global Enable flags in DR7. |
| 73 | |
| 74 | When the Local Enable flag is set, the breakpoint/watchpoint is |
| 75 | enabled only for the current task; the processor automatically |
| 76 | clears this flag on every task switch. When the Global Enable flag |
| 77 | is set, the breakpoint/watchpoint is enabled for all tasks; the |
| 78 | processor never clears this flag. |
| 79 | |
| 80 | Currently, all watchpoint are locally enabled. If you need to |
| 81 | enable them globally, read the comment which pertains to this in |
| 82 | i386_insert_aligned_watchpoint below. */ |
| 83 | #define DR_LOCAL_ENABLE_SHIFT 0 /* Extra shift to the local enable bit. */ |
| 84 | #define DR_GLOBAL_ENABLE_SHIFT 1 /* Extra shift to the global enable bit. */ |
| 85 | #define DR_ENABLE_SIZE 2 /* Two enable bits per debug register. */ |
| 86 | |
| 87 | /* Local and global exact breakpoint enable flags (a.k.a. slowdown |
| 88 | flags). These are only required on i386, to allow detection of the |
| 89 | exact instruction which caused a watchpoint to break; i486 and |
| 90 | later processors do that automatically. We set these flags for |
| 91 | backwards compatibility. */ |
| 92 | #define DR_LOCAL_SLOWDOWN (0x100) |
| 93 | #define DR_GLOBAL_SLOWDOWN (0x200) |
| 94 | |
| 95 | /* Fields reserved by Intel. This includes the GD (General Detect |
| 96 | Enable) flag, which causes a debug exception to be generated when a |
| 97 | MOV instruction accesses one of the debug registers. |
| 98 | |
| 99 | FIXME: My Intel manual says we should use 0xF800, not 0xFC00. */ |
| 100 | #define DR_CONTROL_RESERVED (0xFC00) |
| 101 | |
| 102 | /* Auxiliary helper macros. */ |
| 103 | |
| 104 | /* A value that masks all fields in DR7 that are reserved by Intel. */ |
| 105 | #define I386_DR_CONTROL_MASK (~DR_CONTROL_RESERVED) |
| 106 | |
| 107 | /* The I'th debug register is vacant if its Local and Global Enable |
| 108 | bits are reset in the Debug Control register. */ |
| 109 | #define I386_DR_VACANT(state, i) \ |
| 110 | (((state)->dr_control_mirror & (3 << (DR_ENABLE_SIZE * (i)))) == 0) |
| 111 | |
| 112 | /* Locally enable the break/watchpoint in the I'th debug register. */ |
| 113 | #define I386_DR_LOCAL_ENABLE(state, i) \ |
| 114 | do { \ |
| 115 | (state)->dr_control_mirror |= \ |
| 116 | (1 << (DR_LOCAL_ENABLE_SHIFT + DR_ENABLE_SIZE * (i))); \ |
| 117 | } while (0) |
| 118 | |
| 119 | /* Globally enable the break/watchpoint in the I'th debug register. */ |
| 120 | #define I386_DR_GLOBAL_ENABLE(state, i) \ |
| 121 | do { \ |
| 122 | (state)->dr_control_mirror |= \ |
| 123 | (1 << (DR_GLOBAL_ENABLE_SHIFT + DR_ENABLE_SIZE * (i))); \ |
| 124 | } while (0) |
| 125 | |
| 126 | /* Disable the break/watchpoint in the I'th debug register. */ |
| 127 | #define I386_DR_DISABLE(state, i) \ |
| 128 | do { \ |
| 129 | (state)->dr_control_mirror &= \ |
| 130 | ~(3 << (DR_ENABLE_SIZE * (i))); \ |
| 131 | } while (0) |
| 132 | |
| 133 | /* Set in DR7 the RW and LEN fields for the I'th debug register. */ |
| 134 | #define I386_DR_SET_RW_LEN(state, i, rwlen) \ |
| 135 | do { \ |
| 136 | (state)->dr_control_mirror &= \ |
| 137 | ~(0x0f << (DR_CONTROL_SHIFT + DR_CONTROL_SIZE * (i))); \ |
| 138 | (state)->dr_control_mirror |= \ |
| 139 | ((rwlen) << (DR_CONTROL_SHIFT + DR_CONTROL_SIZE * (i))); \ |
| 140 | } while (0) |
| 141 | |
| 142 | /* Get from DR7 the RW and LEN fields for the I'th debug register. */ |
| 143 | #define I386_DR_GET_RW_LEN(dr7, i) \ |
| 144 | (((dr7) \ |
| 145 | >> (DR_CONTROL_SHIFT + DR_CONTROL_SIZE * (i))) & 0x0f) |
| 146 | |
| 147 | /* Mask that this I'th watchpoint has triggered. */ |
| 148 | #define I386_DR_WATCH_MASK(i) (1 << (i)) |
| 149 | |
| 150 | /* Did the watchpoint whose address is in the I'th register break? */ |
| 151 | #define I386_DR_WATCH_HIT(dr6, i) ((dr6) & (1 << (i))) |
| 152 | |
| 153 | /* A macro to loop over all debug registers. */ |
| 154 | #define ALL_DEBUG_REGISTERS(i) for (i = 0; i < DR_NADDR; i++) |
| 155 | |
| 156 | /* Per-process data. We don't bind this to a per-inferior registry |
| 157 | because of targets like x86 GNU/Linux that need to keep track of |
| 158 | processes that aren't bound to any inferior (e.g., fork children, |
| 159 | checkpoints). */ |
| 160 | |
| 161 | struct i386_process_info |
| 162 | { |
| 163 | /* Linked list. */ |
| 164 | struct i386_process_info *next; |
| 165 | |
| 166 | /* The process identifier. */ |
| 167 | pid_t pid; |
| 168 | |
| 169 | /* Copy of i386 hardware debug registers. */ |
| 170 | struct i386_debug_reg_state state; |
| 171 | }; |
| 172 | |
| 173 | static struct i386_process_info *i386_process_list = NULL; |
| 174 | |
| 175 | /* Find process data for process PID. */ |
| 176 | |
| 177 | static struct i386_process_info * |
| 178 | i386_find_process_pid (pid_t pid) |
| 179 | { |
| 180 | struct i386_process_info *proc; |
| 181 | |
| 182 | for (proc = i386_process_list; proc; proc = proc->next) |
| 183 | if (proc->pid == pid) |
| 184 | return proc; |
| 185 | |
| 186 | return NULL; |
| 187 | } |
| 188 | |
| 189 | /* Add process data for process PID. Returns newly allocated info |
| 190 | object. */ |
| 191 | |
| 192 | static struct i386_process_info * |
| 193 | i386_add_process (pid_t pid) |
| 194 | { |
| 195 | struct i386_process_info *proc; |
| 196 | |
| 197 | proc = xcalloc (1, sizeof (*proc)); |
| 198 | proc->pid = pid; |
| 199 | |
| 200 | proc->next = i386_process_list; |
| 201 | i386_process_list = proc; |
| 202 | |
| 203 | return proc; |
| 204 | } |
| 205 | |
| 206 | /* Get data specific info for process PID, creating it if necessary. |
| 207 | Never returns NULL. */ |
| 208 | |
| 209 | static struct i386_process_info * |
| 210 | i386_process_info_get (pid_t pid) |
| 211 | { |
| 212 | struct i386_process_info *proc; |
| 213 | |
| 214 | proc = i386_find_process_pid (pid); |
| 215 | if (proc == NULL) |
| 216 | proc = i386_add_process (pid); |
| 217 | |
| 218 | return proc; |
| 219 | } |
| 220 | |
| 221 | /* Get debug registers state for process PID. */ |
| 222 | |
| 223 | struct i386_debug_reg_state * |
| 224 | i386_debug_reg_state (pid_t pid) |
| 225 | { |
| 226 | return &i386_process_info_get (pid)->state; |
| 227 | } |
| 228 | |
| 229 | /* See declaration in i386-nat.h. */ |
| 230 | |
| 231 | void |
| 232 | i386_forget_process (pid_t pid) |
| 233 | { |
| 234 | struct i386_process_info *proc, **proc_link; |
| 235 | |
| 236 | proc = i386_process_list; |
| 237 | proc_link = &i386_process_list; |
| 238 | |
| 239 | while (proc != NULL) |
| 240 | { |
| 241 | if (proc->pid == pid) |
| 242 | { |
| 243 | *proc_link = proc->next; |
| 244 | |
| 245 | xfree (proc); |
| 246 | return; |
| 247 | } |
| 248 | |
| 249 | proc_link = &proc->next; |
| 250 | proc = *proc_link; |
| 251 | } |
| 252 | } |
| 253 | |
| 254 | /* Whether or not to print the mirrored debug registers. */ |
| 255 | static int maint_show_dr; |
| 256 | |
| 257 | /* Types of operations supported by i386_handle_nonaligned_watchpoint. */ |
| 258 | typedef enum { WP_INSERT, WP_REMOVE, WP_COUNT } i386_wp_op_t; |
| 259 | |
| 260 | /* Internal functions. */ |
| 261 | |
| 262 | /* Return the value of a 4-bit field for DR7 suitable for watching a |
| 263 | region of LEN bytes for accesses of type TYPE. LEN is assumed to |
| 264 | have the value of 1, 2, or 4. */ |
| 265 | static unsigned i386_length_and_rw_bits (int len, enum target_hw_bp_type type); |
| 266 | |
| 267 | /* Insert a watchpoint at address ADDR, which is assumed to be aligned |
| 268 | according to the length of the region to watch. LEN_RW_BITS is the |
| 269 | value of the bit-field from DR7 which describes the length and |
| 270 | access type of the region to be watched by this watchpoint. Return |
| 271 | 0 on success, -1 on failure. */ |
| 272 | static int i386_insert_aligned_watchpoint (struct i386_debug_reg_state *state, |
| 273 | CORE_ADDR addr, |
| 274 | unsigned len_rw_bits); |
| 275 | |
| 276 | /* Remove a watchpoint at address ADDR, which is assumed to be aligned |
| 277 | according to the length of the region to watch. LEN_RW_BITS is the |
| 278 | value of the bits from DR7 which describes the length and access |
| 279 | type of the region watched by this watchpoint. Return 0 on |
| 280 | success, -1 on failure. */ |
| 281 | static int i386_remove_aligned_watchpoint (struct i386_debug_reg_state *state, |
| 282 | CORE_ADDR addr, |
| 283 | unsigned len_rw_bits); |
| 284 | |
| 285 | /* Insert or remove a (possibly non-aligned) watchpoint, or count the |
| 286 | number of debug registers required to watch a region at address |
| 287 | ADDR whose length is LEN for accesses of type TYPE. Return 0 on |
| 288 | successful insertion or removal, a positive number when queried |
| 289 | about the number of registers, or -1 on failure. If WHAT is not a |
| 290 | valid value, bombs through internal_error. */ |
| 291 | static int i386_handle_nonaligned_watchpoint (struct i386_debug_reg_state *state, |
| 292 | i386_wp_op_t what, |
| 293 | CORE_ADDR addr, int len, |
| 294 | enum target_hw_bp_type type); |
| 295 | |
| 296 | /* Implementation. */ |
| 297 | |
| 298 | /* Clear the reference counts and forget everything we knew about the |
| 299 | debug registers. */ |
| 300 | |
| 301 | void |
| 302 | i386_cleanup_dregs (void) |
| 303 | { |
| 304 | /* Starting from scratch has the same effect. */ |
| 305 | i386_forget_process (ptid_get_pid (inferior_ptid)); |
| 306 | } |
| 307 | |
| 308 | /* Print the values of the mirrored debug registers. This is called |
| 309 | when maint_show_dr is non-zero. To set that up, type "maint |
| 310 | show-debug-regs" at GDB's prompt. */ |
| 311 | |
| 312 | static void |
| 313 | i386_show_dr (struct i386_debug_reg_state *state, |
| 314 | const char *func, CORE_ADDR addr, |
| 315 | int len, enum target_hw_bp_type type) |
| 316 | { |
| 317 | int addr_size = gdbarch_addr_bit (target_gdbarch ()) / 8; |
| 318 | int i; |
| 319 | |
| 320 | puts_unfiltered (func); |
| 321 | if (addr || len) |
| 322 | printf_unfiltered (" (addr=%lx, len=%d, type=%s)", |
| 323 | /* This code is for ia32, so casting CORE_ADDR |
| 324 | to unsigned long should be okay. */ |
| 325 | (unsigned long)addr, len, |
| 326 | type == hw_write ? "data-write" |
| 327 | : (type == hw_read ? "data-read" |
| 328 | : (type == hw_access ? "data-read/write" |
| 329 | : (type == hw_execute ? "instruction-execute" |
| 330 | /* FIXME: if/when I/O read/write |
| 331 | watchpoints are supported, add them |
| 332 | here. */ |
| 333 | : "??unknown??")))); |
| 334 | puts_unfiltered (":\n"); |
| 335 | printf_unfiltered ("\tCONTROL (DR7): %s STATUS (DR6): %s\n", |
| 336 | phex (state->dr_control_mirror, 8), |
| 337 | phex (state->dr_status_mirror, 8)); |
| 338 | ALL_DEBUG_REGISTERS(i) |
| 339 | { |
| 340 | printf_unfiltered ("\ |
| 341 | \tDR%d: addr=0x%s, ref.count=%d DR%d: addr=0x%s, ref.count=%d\n", |
| 342 | i, phex (state->dr_mirror[i], addr_size), |
| 343 | state->dr_ref_count[i], |
| 344 | i + 1, phex (state->dr_mirror[i + 1], addr_size), |
| 345 | state->dr_ref_count[i+1]); |
| 346 | i++; |
| 347 | } |
| 348 | } |
| 349 | |
| 350 | /* Return the value of a 4-bit field for DR7 suitable for watching a |
| 351 | region of LEN bytes for accesses of type TYPE. LEN is assumed to |
| 352 | have the value of 1, 2, or 4. */ |
| 353 | |
| 354 | static unsigned |
| 355 | i386_length_and_rw_bits (int len, enum target_hw_bp_type type) |
| 356 | { |
| 357 | unsigned rw; |
| 358 | |
| 359 | switch (type) |
| 360 | { |
| 361 | case hw_execute: |
| 362 | rw = DR_RW_EXECUTE; |
| 363 | break; |
| 364 | case hw_write: |
| 365 | rw = DR_RW_WRITE; |
| 366 | break; |
| 367 | case hw_read: |
| 368 | internal_error (__FILE__, __LINE__, |
| 369 | _("The i386 doesn't support " |
| 370 | "data-read watchpoints.\n")); |
| 371 | case hw_access: |
| 372 | rw = DR_RW_READ; |
| 373 | break; |
| 374 | #if 0 |
| 375 | /* Not yet supported. */ |
| 376 | case hw_io_access: |
| 377 | rw = DR_RW_IORW; |
| 378 | break; |
| 379 | #endif |
| 380 | default: |
| 381 | internal_error (__FILE__, __LINE__, _("\ |
| 382 | Invalid hardware breakpoint type %d in i386_length_and_rw_bits.\n"), |
| 383 | (int) type); |
| 384 | } |
| 385 | |
| 386 | switch (len) |
| 387 | { |
| 388 | case 1: |
| 389 | return (DR_LEN_1 | rw); |
| 390 | case 2: |
| 391 | return (DR_LEN_2 | rw); |
| 392 | case 4: |
| 393 | return (DR_LEN_4 | rw); |
| 394 | case 8: |
| 395 | if (TARGET_HAS_DR_LEN_8) |
| 396 | return (DR_LEN_8 | rw); |
| 397 | /* ELSE FALL THROUGH */ |
| 398 | default: |
| 399 | internal_error (__FILE__, __LINE__, _("\ |
| 400 | Invalid hardware breakpoint length %d in i386_length_and_rw_bits.\n"), len); |
| 401 | } |
| 402 | } |
| 403 | |
| 404 | /* Insert a watchpoint at address ADDR, which is assumed to be aligned |
| 405 | according to the length of the region to watch. LEN_RW_BITS is the |
| 406 | value of the bits from DR7 which describes the length and access |
| 407 | type of the region to be watched by this watchpoint. Return 0 on |
| 408 | success, -1 on failure. */ |
| 409 | |
| 410 | static int |
| 411 | i386_insert_aligned_watchpoint (struct i386_debug_reg_state *state, |
| 412 | CORE_ADDR addr, unsigned len_rw_bits) |
| 413 | { |
| 414 | int i; |
| 415 | |
| 416 | if (!i386_dr_low.set_addr || !i386_dr_low.set_control) |
| 417 | return -1; |
| 418 | |
| 419 | /* First, look for an occupied debug register with the same address |
| 420 | and the same RW and LEN definitions. If we find one, we can |
| 421 | reuse it for this watchpoint as well (and save a register). */ |
| 422 | ALL_DEBUG_REGISTERS(i) |
| 423 | { |
| 424 | if (!I386_DR_VACANT (state, i) |
| 425 | && state->dr_mirror[i] == addr |
| 426 | && I386_DR_GET_RW_LEN (state->dr_control_mirror, i) == len_rw_bits) |
| 427 | { |
| 428 | state->dr_ref_count[i]++; |
| 429 | return 0; |
| 430 | } |
| 431 | } |
| 432 | |
| 433 | /* Next, look for a vacant debug register. */ |
| 434 | ALL_DEBUG_REGISTERS(i) |
| 435 | { |
| 436 | if (I386_DR_VACANT (state, i)) |
| 437 | break; |
| 438 | } |
| 439 | |
| 440 | /* No more debug registers! */ |
| 441 | if (i >= DR_NADDR) |
| 442 | return -1; |
| 443 | |
| 444 | /* Now set up the register I to watch our region. */ |
| 445 | |
| 446 | /* Record the info in our local mirrored array. */ |
| 447 | state->dr_mirror[i] = addr; |
| 448 | state->dr_ref_count[i] = 1; |
| 449 | I386_DR_SET_RW_LEN (state, i, len_rw_bits); |
| 450 | /* Note: we only enable the watchpoint locally, i.e. in the current |
| 451 | task. Currently, no i386 target allows or supports global |
| 452 | watchpoints; however, if any target would want that in the |
| 453 | future, GDB should probably provide a command to control whether |
| 454 | to enable watchpoints globally or locally, and the code below |
| 455 | should use global or local enable and slow-down flags as |
| 456 | appropriate. */ |
| 457 | I386_DR_LOCAL_ENABLE (state, i); |
| 458 | state->dr_control_mirror |= DR_LOCAL_SLOWDOWN; |
| 459 | state->dr_control_mirror &= I386_DR_CONTROL_MASK; |
| 460 | |
| 461 | return 0; |
| 462 | } |
| 463 | |
| 464 | /* Remove a watchpoint at address ADDR, which is assumed to be aligned |
| 465 | according to the length of the region to watch. LEN_RW_BITS is the |
| 466 | value of the bits from DR7 which describes the length and access |
| 467 | type of the region watched by this watchpoint. Return 0 on |
| 468 | success, -1 on failure. */ |
| 469 | |
| 470 | static int |
| 471 | i386_remove_aligned_watchpoint (struct i386_debug_reg_state *state, |
| 472 | CORE_ADDR addr, unsigned len_rw_bits) |
| 473 | { |
| 474 | int i, retval = -1; |
| 475 | |
| 476 | ALL_DEBUG_REGISTERS(i) |
| 477 | { |
| 478 | if (!I386_DR_VACANT (state, i) |
| 479 | && state->dr_mirror[i] == addr |
| 480 | && I386_DR_GET_RW_LEN (state->dr_control_mirror, i) == len_rw_bits) |
| 481 | { |
| 482 | if (--state->dr_ref_count[i] == 0) /* no longer in use? */ |
| 483 | { |
| 484 | /* Reset our mirror. */ |
| 485 | state->dr_mirror[i] = 0; |
| 486 | I386_DR_DISABLE (state, i); |
| 487 | } |
| 488 | retval = 0; |
| 489 | } |
| 490 | } |
| 491 | |
| 492 | return retval; |
| 493 | } |
| 494 | |
| 495 | /* Insert or remove a (possibly non-aligned) watchpoint, or count the |
| 496 | number of debug registers required to watch a region at address |
| 497 | ADDR whose length is LEN for accesses of type TYPE. Return 0 on |
| 498 | successful insertion or removal, a positive number when queried |
| 499 | about the number of registers, or -1 on failure. If WHAT is not a |
| 500 | valid value, bombs through internal_error. */ |
| 501 | |
| 502 | static int |
| 503 | i386_handle_nonaligned_watchpoint (struct i386_debug_reg_state *state, |
| 504 | i386_wp_op_t what, CORE_ADDR addr, int len, |
| 505 | enum target_hw_bp_type type) |
| 506 | { |
| 507 | int retval = 0; |
| 508 | int max_wp_len = TARGET_HAS_DR_LEN_8 ? 8 : 4; |
| 509 | |
| 510 | static int size_try_array[8][8] = |
| 511 | { |
| 512 | {1, 1, 1, 1, 1, 1, 1, 1}, /* Trying size one. */ |
| 513 | {2, 1, 2, 1, 2, 1, 2, 1}, /* Trying size two. */ |
| 514 | {2, 1, 2, 1, 2, 1, 2, 1}, /* Trying size three. */ |
| 515 | {4, 1, 2, 1, 4, 1, 2, 1}, /* Trying size four. */ |
| 516 | {4, 1, 2, 1, 4, 1, 2, 1}, /* Trying size five. */ |
| 517 | {4, 1, 2, 1, 4, 1, 2, 1}, /* Trying size six. */ |
| 518 | {4, 1, 2, 1, 4, 1, 2, 1}, /* Trying size seven. */ |
| 519 | {8, 1, 2, 1, 4, 1, 2, 1}, /* Trying size eight. */ |
| 520 | }; |
| 521 | |
| 522 | while (len > 0) |
| 523 | { |
| 524 | int align = addr % max_wp_len; |
| 525 | /* Four (eight on AMD64) is the maximum length a debug register |
| 526 | can watch. */ |
| 527 | int try = (len > max_wp_len ? (max_wp_len - 1) : len - 1); |
| 528 | int size = size_try_array[try][align]; |
| 529 | |
| 530 | if (what == WP_COUNT) |
| 531 | { |
| 532 | /* size_try_array[] is defined such that each iteration |
| 533 | through the loop is guaranteed to produce an address and a |
| 534 | size that can be watched with a single debug register. |
| 535 | Thus, for counting the registers required to watch a |
| 536 | region, we simply need to increment the count on each |
| 537 | iteration. */ |
| 538 | retval++; |
| 539 | } |
| 540 | else |
| 541 | { |
| 542 | unsigned len_rw = i386_length_and_rw_bits (size, type); |
| 543 | |
| 544 | if (what == WP_INSERT) |
| 545 | retval = i386_insert_aligned_watchpoint (state, addr, len_rw); |
| 546 | else if (what == WP_REMOVE) |
| 547 | retval = i386_remove_aligned_watchpoint (state, addr, len_rw); |
| 548 | else |
| 549 | internal_error (__FILE__, __LINE__, _("\ |
| 550 | Invalid value %d of operation in i386_handle_nonaligned_watchpoint.\n"), |
| 551 | (int)what); |
| 552 | if (retval) |
| 553 | break; |
| 554 | } |
| 555 | |
| 556 | addr += size; |
| 557 | len -= size; |
| 558 | } |
| 559 | |
| 560 | return retval; |
| 561 | } |
| 562 | |
| 563 | /* Update the inferior's debug registers with the new debug registers |
| 564 | state, in NEW_STATE, and then update our local mirror to match. */ |
| 565 | |
| 566 | static void |
| 567 | i386_update_inferior_debug_regs (struct i386_debug_reg_state *new_state) |
| 568 | { |
| 569 | struct i386_debug_reg_state *state |
| 570 | = i386_debug_reg_state (ptid_get_pid (inferior_ptid)); |
| 571 | int i; |
| 572 | |
| 573 | ALL_DEBUG_REGISTERS (i) |
| 574 | { |
| 575 | if (I386_DR_VACANT (new_state, i) != I386_DR_VACANT (state, i)) |
| 576 | i386_dr_low.set_addr (i, new_state->dr_mirror[i]); |
| 577 | else |
| 578 | gdb_assert (new_state->dr_mirror[i] == state->dr_mirror[i]); |
| 579 | } |
| 580 | |
| 581 | if (new_state->dr_control_mirror != state->dr_control_mirror) |
| 582 | i386_dr_low.set_control (new_state->dr_control_mirror); |
| 583 | |
| 584 | *state = *new_state; |
| 585 | } |
| 586 | |
| 587 | /* Insert a watchpoint to watch a memory region which starts at |
| 588 | address ADDR and whose length is LEN bytes. Watch memory accesses |
| 589 | of the type TYPE. Return 0 on success, -1 on failure. */ |
| 590 | |
| 591 | static int |
| 592 | i386_insert_watchpoint (CORE_ADDR addr, int len, int type, |
| 593 | struct expression *cond) |
| 594 | { |
| 595 | struct i386_debug_reg_state *state |
| 596 | = i386_debug_reg_state (ptid_get_pid (inferior_ptid)); |
| 597 | int retval; |
| 598 | /* Work on a local copy of the debug registers, and on success, |
| 599 | commit the change back to the inferior. */ |
| 600 | struct i386_debug_reg_state local_state = *state; |
| 601 | |
| 602 | if (type == hw_read) |
| 603 | return 1; /* unsupported */ |
| 604 | |
| 605 | if (((len != 1 && len !=2 && len !=4) && !(TARGET_HAS_DR_LEN_8 && len == 8)) |
| 606 | || addr % len != 0) |
| 607 | retval = i386_handle_nonaligned_watchpoint (&local_state, |
| 608 | WP_INSERT, addr, len, type); |
| 609 | else |
| 610 | { |
| 611 | unsigned len_rw = i386_length_and_rw_bits (len, type); |
| 612 | |
| 613 | retval = i386_insert_aligned_watchpoint (&local_state, |
| 614 | addr, len_rw); |
| 615 | } |
| 616 | |
| 617 | if (retval == 0) |
| 618 | i386_update_inferior_debug_regs (&local_state); |
| 619 | |
| 620 | if (maint_show_dr) |
| 621 | i386_show_dr (state, "insert_watchpoint", addr, len, type); |
| 622 | |
| 623 | return retval; |
| 624 | } |
| 625 | |
| 626 | /* Remove a watchpoint that watched the memory region which starts at |
| 627 | address ADDR, whose length is LEN bytes, and for accesses of the |
| 628 | type TYPE. Return 0 on success, -1 on failure. */ |
| 629 | static int |
| 630 | i386_remove_watchpoint (CORE_ADDR addr, int len, int type, |
| 631 | struct expression *cond) |
| 632 | { |
| 633 | struct i386_debug_reg_state *state |
| 634 | = i386_debug_reg_state (ptid_get_pid (inferior_ptid)); |
| 635 | int retval; |
| 636 | /* Work on a local copy of the debug registers, and on success, |
| 637 | commit the change back to the inferior. */ |
| 638 | struct i386_debug_reg_state local_state = *state; |
| 639 | |
| 640 | if (((len != 1 && len !=2 && len !=4) && !(TARGET_HAS_DR_LEN_8 && len == 8)) |
| 641 | || addr % len != 0) |
| 642 | retval = i386_handle_nonaligned_watchpoint (&local_state, |
| 643 | WP_REMOVE, addr, len, type); |
| 644 | else |
| 645 | { |
| 646 | unsigned len_rw = i386_length_and_rw_bits (len, type); |
| 647 | |
| 648 | retval = i386_remove_aligned_watchpoint (&local_state, |
| 649 | addr, len_rw); |
| 650 | } |
| 651 | |
| 652 | if (retval == 0) |
| 653 | i386_update_inferior_debug_regs (&local_state); |
| 654 | |
| 655 | if (maint_show_dr) |
| 656 | i386_show_dr (state, "remove_watchpoint", addr, len, type); |
| 657 | |
| 658 | return retval; |
| 659 | } |
| 660 | |
| 661 | /* Return non-zero if we can watch a memory region that starts at |
| 662 | address ADDR and whose length is LEN bytes. */ |
| 663 | |
| 664 | static int |
| 665 | i386_region_ok_for_watchpoint (CORE_ADDR addr, int len) |
| 666 | { |
| 667 | struct i386_debug_reg_state *state |
| 668 | = i386_debug_reg_state (ptid_get_pid (inferior_ptid)); |
| 669 | int nregs; |
| 670 | |
| 671 | /* Compute how many aligned watchpoints we would need to cover this |
| 672 | region. */ |
| 673 | nregs = i386_handle_nonaligned_watchpoint (state, |
| 674 | WP_COUNT, addr, len, hw_write); |
| 675 | return nregs <= DR_NADDR ? 1 : 0; |
| 676 | } |
| 677 | |
| 678 | /* If the inferior has some watchpoint that triggered, set the |
| 679 | address associated with that watchpoint and return non-zero. |
| 680 | Otherwise, return zero. */ |
| 681 | |
| 682 | static int |
| 683 | i386_stopped_data_address (struct target_ops *ops, CORE_ADDR *addr_p) |
| 684 | { |
| 685 | struct i386_debug_reg_state *state |
| 686 | = i386_debug_reg_state (ptid_get_pid (inferior_ptid)); |
| 687 | CORE_ADDR addr = 0; |
| 688 | int i; |
| 689 | int rc = 0; |
| 690 | /* The current thread's DR_STATUS. We always need to read this to |
| 691 | check whether some watchpoint caused the trap. */ |
| 692 | unsigned status; |
| 693 | /* We need DR_CONTROL as well, but only iff DR_STATUS indicates a |
| 694 | data breakpoint trap. Only fetch it when necessary, to avoid an |
| 695 | unnecessary extra syscall when no watchpoint triggered. */ |
| 696 | int control_p = 0; |
| 697 | unsigned control = 0; |
| 698 | |
| 699 | /* In non-stop/async, threads can be running while we change the |
| 700 | STATE (and friends). Say, we set a watchpoint, and let threads |
| 701 | resume. Now, say you delete the watchpoint, or add/remove |
| 702 | watchpoints such that STATE changes while threads are running. |
| 703 | On targets that support non-stop, inserting/deleting watchpoints |
| 704 | updates the STATE only. It does not update the real thread's |
| 705 | debug registers; that's only done prior to resume. Instead, if |
| 706 | threads are running when the mirror changes, a temporary and |
| 707 | transparent stop on all threads is forced so they can get their |
| 708 | copy of the debug registers updated on re-resume. Now, say, |
| 709 | a thread hit a watchpoint before having been updated with the new |
| 710 | STATE contents, and we haven't yet handled the corresponding |
| 711 | SIGTRAP. If we trusted STATE below, we'd mistake the real |
| 712 | trapped address (from the last time we had updated debug |
| 713 | registers in the thread) with whatever was currently in STATE. |
| 714 | So to fix this, STATE always represents intention, what we _want_ |
| 715 | threads to have in debug registers. To get at the address and |
| 716 | cause of the trap, we need to read the state the thread still has |
| 717 | in its debug registers. |
| 718 | |
| 719 | In sum, always get the current debug register values the current |
| 720 | thread has, instead of trusting the global mirror. If the thread |
| 721 | was running when we last changed watchpoints, the mirror no |
| 722 | longer represents what was set in this thread's debug |
| 723 | registers. */ |
| 724 | status = i386_dr_low.get_status (); |
| 725 | |
| 726 | ALL_DEBUG_REGISTERS(i) |
| 727 | { |
| 728 | if (!I386_DR_WATCH_HIT (status, i)) |
| 729 | continue; |
| 730 | |
| 731 | if (!control_p) |
| 732 | { |
| 733 | control = i386_dr_low.get_control (); |
| 734 | control_p = 1; |
| 735 | } |
| 736 | |
| 737 | /* This second condition makes sure DRi is set up for a data |
| 738 | watchpoint, not a hardware breakpoint. The reason is that |
| 739 | GDB doesn't call the target_stopped_data_address method |
| 740 | except for data watchpoints. In other words, I'm being |
| 741 | paranoiac. */ |
| 742 | if (I386_DR_GET_RW_LEN (control, i) != 0) |
| 743 | { |
| 744 | addr = i386_dr_low.get_addr (i); |
| 745 | rc = 1; |
| 746 | if (maint_show_dr) |
| 747 | i386_show_dr (state, "watchpoint_hit", addr, -1, hw_write); |
| 748 | } |
| 749 | } |
| 750 | if (maint_show_dr && addr == 0) |
| 751 | i386_show_dr (state, "stopped_data_addr", 0, 0, hw_write); |
| 752 | |
| 753 | if (rc) |
| 754 | *addr_p = addr; |
| 755 | return rc; |
| 756 | } |
| 757 | |
| 758 | static int |
| 759 | i386_stopped_by_watchpoint (void) |
| 760 | { |
| 761 | CORE_ADDR addr = 0; |
| 762 | return i386_stopped_data_address (¤t_target, &addr); |
| 763 | } |
| 764 | |
| 765 | /* Insert a hardware-assisted breakpoint at BP_TGT->placed_address. |
| 766 | Return 0 on success, EBUSY on failure. */ |
| 767 | static int |
| 768 | i386_insert_hw_breakpoint (struct gdbarch *gdbarch, |
| 769 | struct bp_target_info *bp_tgt) |
| 770 | { |
| 771 | struct i386_debug_reg_state *state |
| 772 | = i386_debug_reg_state (ptid_get_pid (inferior_ptid)); |
| 773 | unsigned len_rw = i386_length_and_rw_bits (1, hw_execute); |
| 774 | CORE_ADDR addr = bp_tgt->placed_address; |
| 775 | /* Work on a local copy of the debug registers, and on success, |
| 776 | commit the change back to the inferior. */ |
| 777 | struct i386_debug_reg_state local_state = *state; |
| 778 | int retval = i386_insert_aligned_watchpoint (&local_state, |
| 779 | addr, len_rw) ? EBUSY : 0; |
| 780 | |
| 781 | if (retval == 0) |
| 782 | i386_update_inferior_debug_regs (&local_state); |
| 783 | |
| 784 | if (maint_show_dr) |
| 785 | i386_show_dr (state, "insert_hwbp", addr, 1, hw_execute); |
| 786 | |
| 787 | return retval; |
| 788 | } |
| 789 | |
| 790 | /* Remove a hardware-assisted breakpoint at BP_TGT->placed_address. |
| 791 | Return 0 on success, -1 on failure. */ |
| 792 | |
| 793 | static int |
| 794 | i386_remove_hw_breakpoint (struct gdbarch *gdbarch, |
| 795 | struct bp_target_info *bp_tgt) |
| 796 | { |
| 797 | struct i386_debug_reg_state *state |
| 798 | = i386_debug_reg_state (ptid_get_pid (inferior_ptid)); |
| 799 | unsigned len_rw = i386_length_and_rw_bits (1, hw_execute); |
| 800 | CORE_ADDR addr = bp_tgt->placed_address; |
| 801 | /* Work on a local copy of the debug registers, and on success, |
| 802 | commit the change back to the inferior. */ |
| 803 | struct i386_debug_reg_state local_state = *state; |
| 804 | int retval = i386_remove_aligned_watchpoint (&local_state, |
| 805 | addr, len_rw); |
| 806 | |
| 807 | if (retval == 0) |
| 808 | i386_update_inferior_debug_regs (&local_state); |
| 809 | |
| 810 | if (maint_show_dr) |
| 811 | i386_show_dr (state, "remove_hwbp", addr, 1, hw_execute); |
| 812 | |
| 813 | return retval; |
| 814 | } |
| 815 | |
| 816 | /* Returns the number of hardware watchpoints of type TYPE that we can |
| 817 | set. Value is positive if we can set CNT watchpoints, zero if |
| 818 | setting watchpoints of type TYPE is not supported, and negative if |
| 819 | CNT is more than the maximum number of watchpoints of type TYPE |
| 820 | that we can support. TYPE is one of bp_hardware_watchpoint, |
| 821 | bp_read_watchpoint, bp_write_watchpoint, or bp_hardware_breakpoint. |
| 822 | CNT is the number of such watchpoints used so far (including this |
| 823 | one). OTHERTYPE is non-zero if other types of watchpoints are |
| 824 | currently enabled. |
| 825 | |
| 826 | We always return 1 here because we don't have enough information |
| 827 | about possible overlap of addresses that they want to watch. As an |
| 828 | extreme example, consider the case where all the watchpoints watch |
| 829 | the same address and the same region length: then we can handle a |
| 830 | virtually unlimited number of watchpoints, due to debug register |
| 831 | sharing implemented via reference counts in i386-nat.c. */ |
| 832 | |
| 833 | static int |
| 834 | i386_can_use_hw_breakpoint (int type, int cnt, int othertype) |
| 835 | { |
| 836 | return 1; |
| 837 | } |
| 838 | |
| 839 | static void |
| 840 | add_show_debug_regs_command (void) |
| 841 | { |
| 842 | /* A maintenance command to enable printing the internal DRi mirror |
| 843 | variables. */ |
| 844 | add_setshow_boolean_cmd ("show-debug-regs", class_maintenance, |
| 845 | &maint_show_dr, _("\ |
| 846 | Set whether to show variables that mirror the x86 debug registers."), _("\ |
| 847 | Show whether to show variables that mirror the x86 debug registers."), _("\ |
| 848 | Use \"on\" to enable, \"off\" to disable.\n\ |
| 849 | If enabled, the debug registers values are shown when GDB inserts\n\ |
| 850 | or removes a hardware breakpoint or watchpoint, and when the inferior\n\ |
| 851 | triggers a breakpoint or watchpoint."), |
| 852 | NULL, |
| 853 | NULL, |
| 854 | &maintenance_set_cmdlist, |
| 855 | &maintenance_show_cmdlist); |
| 856 | } |
| 857 | |
| 858 | /* There are only two global functions left. */ |
| 859 | |
| 860 | void |
| 861 | i386_use_watchpoints (struct target_ops *t) |
| 862 | { |
| 863 | /* After a watchpoint trap, the PC points to the instruction after the |
| 864 | one that caused the trap. Therefore we don't need to step over it. |
| 865 | But we do need to reset the status register to avoid another trap. */ |
| 866 | t->to_have_continuable_watchpoint = 1; |
| 867 | |
| 868 | t->to_can_use_hw_breakpoint = i386_can_use_hw_breakpoint; |
| 869 | t->to_region_ok_for_hw_watchpoint = i386_region_ok_for_watchpoint; |
| 870 | t->to_stopped_by_watchpoint = i386_stopped_by_watchpoint; |
| 871 | t->to_stopped_data_address = i386_stopped_data_address; |
| 872 | t->to_insert_watchpoint = i386_insert_watchpoint; |
| 873 | t->to_remove_watchpoint = i386_remove_watchpoint; |
| 874 | t->to_insert_hw_breakpoint = i386_insert_hw_breakpoint; |
| 875 | t->to_remove_hw_breakpoint = i386_remove_hw_breakpoint; |
| 876 | } |
| 877 | |
| 878 | void |
| 879 | i386_set_debug_register_length (int len) |
| 880 | { |
| 881 | /* This function should be called only once for each native target. */ |
| 882 | gdb_assert (i386_dr_low.debug_register_length == 0); |
| 883 | gdb_assert (len == 4 || len == 8); |
| 884 | i386_dr_low.debug_register_length = len; |
| 885 | add_show_debug_regs_command (); |
| 886 | } |