| 1 | /* Inline frame unwinder for GDB. |
| 2 | |
| 3 | Copyright (C) 2008-2019 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 "breakpoint.h" |
| 22 | #include "inline-frame.h" |
| 23 | #include "addrmap.h" |
| 24 | #include "block.h" |
| 25 | #include "frame-unwind.h" |
| 26 | #include "inferior.h" |
| 27 | #include "gdbthread.h" |
| 28 | #include "regcache.h" |
| 29 | #include "symtab.h" |
| 30 | #include "common/vec.h" |
| 31 | #include "frame.h" |
| 32 | #include <algorithm> |
| 33 | |
| 34 | /* We need to save a few variables for every thread stopped at the |
| 35 | virtual call site of an inlined function. If there was always a |
| 36 | "struct thread_info", we could hang it off that; in the mean time, |
| 37 | keep our own list. */ |
| 38 | struct inline_state |
| 39 | { |
| 40 | inline_state (thread_info *thread_, int skipped_frames_, CORE_ADDR saved_pc_, |
| 41 | symbol *skipped_symbol_) |
| 42 | : thread (thread_), skipped_frames (skipped_frames_), saved_pc (saved_pc_), |
| 43 | skipped_symbol (skipped_symbol_) |
| 44 | {} |
| 45 | |
| 46 | /* The thread this data relates to. It should be a currently |
| 47 | stopped thread. */ |
| 48 | thread_info *thread; |
| 49 | |
| 50 | /* The number of inlined functions we are skipping. Each of these |
| 51 | functions can be stepped in to. */ |
| 52 | int skipped_frames; |
| 53 | |
| 54 | /* Only valid if SKIPPED_FRAMES is non-zero. This is the PC used |
| 55 | when calculating SKIPPED_FRAMES; used to check whether we have |
| 56 | moved to a new location by user request. If so, we invalidate |
| 57 | any skipped frames. */ |
| 58 | CORE_ADDR saved_pc; |
| 59 | |
| 60 | /* Only valid if SKIPPED_FRAMES is non-zero. This is the symbol |
| 61 | of the outermost skipped inline function. It's used to find the |
| 62 | call site of the current frame. */ |
| 63 | struct symbol *skipped_symbol; |
| 64 | }; |
| 65 | |
| 66 | static std::vector<inline_state> inline_states; |
| 67 | |
| 68 | /* Locate saved inlined frame state for THREAD, if it exists and is |
| 69 | valid. */ |
| 70 | |
| 71 | static struct inline_state * |
| 72 | find_inline_frame_state (thread_info *thread) |
| 73 | { |
| 74 | auto state_it = std::find_if (inline_states.begin (), inline_states.end (), |
| 75 | [thread] (const inline_state &state) |
| 76 | { |
| 77 | return state.thread == thread; |
| 78 | }); |
| 79 | |
| 80 | if (state_it == inline_states.end ()) |
| 81 | return nullptr; |
| 82 | |
| 83 | inline_state &state = *state_it; |
| 84 | struct regcache *regcache = get_thread_regcache (thread); |
| 85 | CORE_ADDR current_pc = regcache_read_pc (regcache); |
| 86 | |
| 87 | if (current_pc != state.saved_pc) |
| 88 | { |
| 89 | /* PC has changed - this context is invalid. Use the |
| 90 | default behavior. */ |
| 91 | |
| 92 | unordered_remove (inline_states, state_it); |
| 93 | return nullptr; |
| 94 | } |
| 95 | |
| 96 | return &state; |
| 97 | } |
| 98 | |
| 99 | /* Forget about any hidden inlined functions in PTID, which is new or |
| 100 | about to be resumed. PTID may be minus_one_ptid (all processes) |
| 101 | or a PID (all threads in this process). */ |
| 102 | |
| 103 | void |
| 104 | clear_inline_frame_state (ptid_t ptid) |
| 105 | { |
| 106 | if (ptid == minus_one_ptid) |
| 107 | { |
| 108 | inline_states.clear (); |
| 109 | return; |
| 110 | } |
| 111 | |
| 112 | if (ptid.is_pid ()) |
| 113 | { |
| 114 | int pid = ptid.pid (); |
| 115 | auto it = std::remove_if (inline_states.begin (), inline_states.end (), |
| 116 | [pid] (const inline_state &state) |
| 117 | { |
| 118 | return pid == state.thread->inf->pid; |
| 119 | }); |
| 120 | |
| 121 | inline_states.erase (it, inline_states.end ()); |
| 122 | |
| 123 | return; |
| 124 | } |
| 125 | |
| 126 | auto it = std::find_if (inline_states.begin (), inline_states.end (), |
| 127 | [&ptid] (const inline_state &state) |
| 128 | { |
| 129 | return ptid == state.thread->ptid; |
| 130 | }); |
| 131 | |
| 132 | if (it != inline_states.end ()) |
| 133 | unordered_remove (inline_states, it); |
| 134 | } |
| 135 | |
| 136 | static void |
| 137 | inline_frame_this_id (struct frame_info *this_frame, |
| 138 | void **this_cache, |
| 139 | struct frame_id *this_id) |
| 140 | { |
| 141 | struct symbol *func; |
| 142 | |
| 143 | /* In order to have a stable frame ID for a given inline function, |
| 144 | we must get the stack / special addresses from the underlying |
| 145 | real frame's this_id method. So we must call |
| 146 | get_prev_frame_always. Because we are inlined into some |
| 147 | function, there must be previous frames, so this is safe - as |
| 148 | long as we're careful not to create any cycles. */ |
| 149 | *this_id = get_frame_id (get_prev_frame_always (this_frame)); |
| 150 | |
| 151 | /* We need a valid frame ID, so we need to be based on a valid |
| 152 | frame. FSF submission NOTE: this would be a good assertion to |
| 153 | apply to all frames, all the time. That would fix the ambiguity |
| 154 | of null_frame_id (between "no/any frame" and "the outermost |
| 155 | frame"). This will take work. */ |
| 156 | gdb_assert (frame_id_p (*this_id)); |
| 157 | |
| 158 | /* For now, require we don't match outer_frame_id either (see |
| 159 | comment above). */ |
| 160 | gdb_assert (!frame_id_eq (*this_id, outer_frame_id)); |
| 161 | |
| 162 | /* Future work NOTE: Alexandre Oliva applied a patch to GCC 4.3 |
| 163 | which generates DW_AT_entry_pc for inlined functions when |
| 164 | possible. If this attribute is available, we should use it |
| 165 | in the frame ID (and eventually, to set breakpoints). */ |
| 166 | func = get_frame_function (this_frame); |
| 167 | gdb_assert (func != NULL); |
| 168 | (*this_id).code_addr = BLOCK_ENTRY_PC (SYMBOL_BLOCK_VALUE (func)); |
| 169 | (*this_id).artificial_depth++; |
| 170 | } |
| 171 | |
| 172 | static struct value * |
| 173 | inline_frame_prev_register (struct frame_info *this_frame, void **this_cache, |
| 174 | int regnum) |
| 175 | { |
| 176 | /* Use get_frame_register_value instead of |
| 177 | frame_unwind_got_register, to avoid requiring this frame's ID. |
| 178 | This frame's ID depends on the previous frame's ID (unusual), and |
| 179 | the previous frame's ID depends on this frame's unwound |
| 180 | registers. If unwinding registers from this frame called |
| 181 | get_frame_id, there would be a loop. |
| 182 | |
| 183 | Do not copy this code into any other unwinder! Inlined functions |
| 184 | are special; other unwinders must not have a dependency on the |
| 185 | previous frame's ID, and therefore can and should use |
| 186 | frame_unwind_got_register instead. */ |
| 187 | return get_frame_register_value (this_frame, regnum); |
| 188 | } |
| 189 | |
| 190 | /* Check whether we are at an inlining site that does not already |
| 191 | have an associated frame. */ |
| 192 | |
| 193 | static int |
| 194 | inline_frame_sniffer (const struct frame_unwind *self, |
| 195 | struct frame_info *this_frame, |
| 196 | void **this_cache) |
| 197 | { |
| 198 | CORE_ADDR this_pc; |
| 199 | const struct block *frame_block, *cur_block; |
| 200 | int depth; |
| 201 | struct frame_info *next_frame; |
| 202 | struct inline_state *state = find_inline_frame_state (inferior_thread ()); |
| 203 | |
| 204 | this_pc = get_frame_address_in_block (this_frame); |
| 205 | frame_block = block_for_pc (this_pc); |
| 206 | if (frame_block == NULL) |
| 207 | return 0; |
| 208 | |
| 209 | /* Calculate DEPTH, the number of inlined functions at this |
| 210 | location. */ |
| 211 | depth = 0; |
| 212 | cur_block = frame_block; |
| 213 | while (BLOCK_SUPERBLOCK (cur_block)) |
| 214 | { |
| 215 | if (block_inlined_p (cur_block)) |
| 216 | depth++; |
| 217 | else if (BLOCK_FUNCTION (cur_block) != NULL) |
| 218 | break; |
| 219 | |
| 220 | cur_block = BLOCK_SUPERBLOCK (cur_block); |
| 221 | } |
| 222 | |
| 223 | /* Check how many inlined functions already have frames. */ |
| 224 | for (next_frame = get_next_frame (this_frame); |
| 225 | next_frame && get_frame_type (next_frame) == INLINE_FRAME; |
| 226 | next_frame = get_next_frame (next_frame)) |
| 227 | { |
| 228 | gdb_assert (depth > 0); |
| 229 | depth--; |
| 230 | } |
| 231 | |
| 232 | /* If this is the topmost frame, or all frames above us are inlined, |
| 233 | then check whether we were requested to skip some frames (so they |
| 234 | can be stepped into later). */ |
| 235 | if (state != NULL && state->skipped_frames > 0 && next_frame == NULL) |
| 236 | { |
| 237 | gdb_assert (depth >= state->skipped_frames); |
| 238 | depth -= state->skipped_frames; |
| 239 | } |
| 240 | |
| 241 | /* If all the inlined functions here already have frames, then pass |
| 242 | to the normal unwinder for this PC. */ |
| 243 | if (depth == 0) |
| 244 | return 0; |
| 245 | |
| 246 | /* If the next frame is an inlined function, but not the outermost, then |
| 247 | we are the next outer. If it is not an inlined function, then we |
| 248 | are the innermost inlined function of a different real frame. */ |
| 249 | return 1; |
| 250 | } |
| 251 | |
| 252 | const struct frame_unwind inline_frame_unwind = { |
| 253 | INLINE_FRAME, |
| 254 | default_frame_unwind_stop_reason, |
| 255 | inline_frame_this_id, |
| 256 | inline_frame_prev_register, |
| 257 | NULL, |
| 258 | inline_frame_sniffer |
| 259 | }; |
| 260 | |
| 261 | /* Return non-zero if BLOCK, an inlined function block containing PC, |
| 262 | has a group of contiguous instructions starting at PC (but not |
| 263 | before it). */ |
| 264 | |
| 265 | static int |
| 266 | block_starting_point_at (CORE_ADDR pc, const struct block *block) |
| 267 | { |
| 268 | const struct blockvector *bv; |
| 269 | struct block *new_block; |
| 270 | |
| 271 | bv = blockvector_for_pc (pc, NULL); |
| 272 | if (BLOCKVECTOR_MAP (bv) == NULL) |
| 273 | return 0; |
| 274 | |
| 275 | new_block = (struct block *) addrmap_find (BLOCKVECTOR_MAP (bv), pc - 1); |
| 276 | if (new_block == NULL) |
| 277 | return 1; |
| 278 | |
| 279 | if (new_block == block || contained_in (new_block, block)) |
| 280 | return 0; |
| 281 | |
| 282 | /* The immediately preceding address belongs to a different block, |
| 283 | which is not a child of this one. Treat this as an entrance into |
| 284 | BLOCK. */ |
| 285 | return 1; |
| 286 | } |
| 287 | |
| 288 | /* Loop over the stop chain and determine if execution stopped in an |
| 289 | inlined frame because of a user breakpoint set at FRAME_BLOCK. */ |
| 290 | |
| 291 | static bool |
| 292 | stopped_by_user_bp_inline_frame (const block *frame_block, bpstat stop_chain) |
| 293 | { |
| 294 | for (bpstat s = stop_chain; s != NULL; s = s->next) |
| 295 | { |
| 296 | struct breakpoint *bpt = s->breakpoint_at; |
| 297 | |
| 298 | if (bpt != NULL && user_breakpoint_p (bpt)) |
| 299 | { |
| 300 | bp_location *loc = s->bp_location_at; |
| 301 | enum bp_loc_type t = loc->loc_type; |
| 302 | |
| 303 | if (t == bp_loc_software_breakpoint |
| 304 | || t == bp_loc_hardware_breakpoint) |
| 305 | { |
| 306 | /* If the location has a function symbol, check whether |
| 307 | the frame was for that inlined function. If it has |
| 308 | no function symbol, then assume it is. I.e., default |
| 309 | to presenting the stop at the innermost inline |
| 310 | function. */ |
| 311 | if (loc->symbol == nullptr |
| 312 | || frame_block == SYMBOL_BLOCK_VALUE (loc->symbol)) |
| 313 | return true; |
| 314 | } |
| 315 | } |
| 316 | } |
| 317 | |
| 318 | return false; |
| 319 | } |
| 320 | |
| 321 | /* See inline-frame.h. */ |
| 322 | |
| 323 | void |
| 324 | skip_inline_frames (thread_info *thread, bpstat stop_chain) |
| 325 | { |
| 326 | const struct block *frame_block, *cur_block; |
| 327 | struct symbol *last_sym = NULL; |
| 328 | int skip_count = 0; |
| 329 | |
| 330 | /* This function is called right after reinitializing the frame |
| 331 | cache. We try not to do more unwinding than absolutely |
| 332 | necessary, for performance. */ |
| 333 | CORE_ADDR this_pc = get_frame_pc (get_current_frame ()); |
| 334 | frame_block = block_for_pc (this_pc); |
| 335 | |
| 336 | if (frame_block != NULL) |
| 337 | { |
| 338 | cur_block = frame_block; |
| 339 | while (BLOCK_SUPERBLOCK (cur_block)) |
| 340 | { |
| 341 | if (block_inlined_p (cur_block)) |
| 342 | { |
| 343 | /* See comments in inline_frame_this_id about this use |
| 344 | of BLOCK_ENTRY_PC. */ |
| 345 | if (BLOCK_ENTRY_PC (cur_block) == this_pc |
| 346 | || block_starting_point_at (this_pc, cur_block)) |
| 347 | { |
| 348 | /* Do not skip the inlined frame if execution |
| 349 | stopped in an inlined frame because of a user |
| 350 | breakpoint for this inline function. */ |
| 351 | if (stopped_by_user_bp_inline_frame (cur_block, stop_chain)) |
| 352 | break; |
| 353 | |
| 354 | skip_count++; |
| 355 | last_sym = BLOCK_FUNCTION (cur_block); |
| 356 | } |
| 357 | else |
| 358 | break; |
| 359 | } |
| 360 | else if (BLOCK_FUNCTION (cur_block) != NULL) |
| 361 | break; |
| 362 | |
| 363 | cur_block = BLOCK_SUPERBLOCK (cur_block); |
| 364 | } |
| 365 | } |
| 366 | |
| 367 | gdb_assert (find_inline_frame_state (thread) == NULL); |
| 368 | inline_states.emplace_back (thread, skip_count, this_pc, last_sym); |
| 369 | |
| 370 | if (skip_count != 0) |
| 371 | reinit_frame_cache (); |
| 372 | } |
| 373 | |
| 374 | /* Step into an inlined function by unhiding it. */ |
| 375 | |
| 376 | void |
| 377 | step_into_inline_frame (thread_info *thread) |
| 378 | { |
| 379 | inline_state *state = find_inline_frame_state (thread); |
| 380 | |
| 381 | gdb_assert (state != NULL && state->skipped_frames > 0); |
| 382 | state->skipped_frames--; |
| 383 | reinit_frame_cache (); |
| 384 | } |
| 385 | |
| 386 | /* Return the number of hidden functions inlined into the current |
| 387 | frame. */ |
| 388 | |
| 389 | int |
| 390 | inline_skipped_frames (thread_info *thread) |
| 391 | { |
| 392 | inline_state *state = find_inline_frame_state (thread); |
| 393 | |
| 394 | if (state == NULL) |
| 395 | return 0; |
| 396 | else |
| 397 | return state->skipped_frames; |
| 398 | } |
| 399 | |
| 400 | /* If one or more inlined functions are hidden, return the symbol for |
| 401 | the function inlined into the current frame. */ |
| 402 | |
| 403 | struct symbol * |
| 404 | inline_skipped_symbol (thread_info *thread) |
| 405 | { |
| 406 | inline_state *state = find_inline_frame_state (thread); |
| 407 | |
| 408 | gdb_assert (state != NULL); |
| 409 | return state->skipped_symbol; |
| 410 | } |
| 411 | |
| 412 | /* Return the number of functions inlined into THIS_FRAME. Some of |
| 413 | the callees may not have associated frames (see |
| 414 | skip_inline_frames). */ |
| 415 | |
| 416 | int |
| 417 | frame_inlined_callees (struct frame_info *this_frame) |
| 418 | { |
| 419 | struct frame_info *next_frame; |
| 420 | int inline_count = 0; |
| 421 | |
| 422 | /* First count how many inlined functions at this PC have frames |
| 423 | above FRAME (are inlined into FRAME). */ |
| 424 | for (next_frame = get_next_frame (this_frame); |
| 425 | next_frame && get_frame_type (next_frame) == INLINE_FRAME; |
| 426 | next_frame = get_next_frame (next_frame)) |
| 427 | inline_count++; |
| 428 | |
| 429 | /* Simulate some most-inner inlined frames which were suppressed, so |
| 430 | they can be stepped into later. If we are unwinding already |
| 431 | outer frames from some non-inlined frame this does not apply. */ |
| 432 | if (next_frame == NULL) |
| 433 | inline_count += inline_skipped_frames (inferior_thread ()); |
| 434 | |
| 435 | return inline_count; |
| 436 | } |