1 /* $NetBSD: db_trace.c,v 1.8 2003/01/17 22:28:48 thorpej Exp $ */ 2 3 /*- 4 * Copyright (c) 2000, 2001 Ben Harris 5 * Copyright (c) 1996 Scott K. Stevens 6 * 7 * Mach Operating System 8 * Copyright (c) 1991,1990 Carnegie Mellon University 9 * All Rights Reserved. 10 * 11 * Permission to use, copy, modify and distribute this software and its 12 * documentation is hereby granted, provided that both the copyright 13 * notice and this permission notice appear in all copies of the 14 * software, derivative works or modified versions, and any portions 15 * thereof, and that both notices appear in supporting documentation. 16 * 17 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 18 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR 19 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 20 * 21 * Carnegie Mellon requests users of this software to return to 22 * 23 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 24 * School of Computer Science 25 * Carnegie Mellon University 26 * Pittsburgh PA 15213-3890 27 * 28 * any improvements or extensions that they make and grant Carnegie the 29 * rights to redistribute these changes. 30 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 #include <sys/param.h> 35 #include <sys/systm.h> 36 37 38 #include <sys/proc.h> 39 #include <sys/kdb.h> 40 #include <sys/stack.h> 41 #include <machine/armreg.h> 42 #include <machine/asm.h> 43 #include <machine/cpufunc.h> 44 #include <machine/db_machdep.h> 45 #include <machine/pcb.h> 46 #include <machine/stack.h> 47 #include <machine/vmparam.h> 48 #include <ddb/ddb.h> 49 #include <ddb/db_access.h> 50 #include <ddb/db_sym.h> 51 #include <ddb/db_output.h> 52 53 #ifdef __ARM_EABI__ 54 /* 55 * Definitions for the instruction interpreter. 56 * 57 * The ARM EABI specifies how to perform the frame unwinding in the 58 * Exception Handling ABI for the ARM Architecture document. To perform 59 * the unwind we need to know the initial frame pointer, stack pointer, 60 * link register and program counter. We then find the entry within the 61 * index table that points to the function the program counter is within. 62 * This gives us either a list of three instructions to process, a 31-bit 63 * relative offset to a table of instructions, or a value telling us 64 * we can't unwind any further. 65 * 66 * When we have the instructions to process we need to decode them 67 * following table 4 in section 9.3. This describes a collection of bit 68 * patterns to encode that steps to take to update the stack pointer and 69 * link register to the correct values at the start of the function. 70 */ 71 72 /* A special case when we are unable to unwind past this function */ 73 #define EXIDX_CANTUNWIND 1 74 75 /* The register names */ 76 #define FP 11 77 #define SP 13 78 #define LR 14 79 #define PC 15 80 81 /* 82 * These are set in the linker script. Their addresses will be 83 * either the start or end of the exception table or index. 84 */ 85 extern int extab_start, extab_end, exidx_start, exidx_end; 86 87 /* 88 * Entry types. 89 * These are the only entry types that have been seen in the kernel. 90 */ 91 #define ENTRY_MASK 0xff000000 92 #define ENTRY_ARM_SU16 0x80000000 93 #define ENTRY_ARM_LU16 0x81000000 94 95 /* Instruction masks. */ 96 #define INSN_VSP_MASK 0xc0 97 #define INSN_VSP_SIZE_MASK 0x3f 98 #define INSN_STD_MASK 0xf0 99 #define INSN_STD_DATA_MASK 0x0f 100 #define INSN_POP_TYPE_MASK 0x08 101 #define INSN_POP_COUNT_MASK 0x07 102 #define INSN_VSP_LARGE_INC_MASK 0xff 103 104 /* Instruction definitions */ 105 #define INSN_VSP_INC 0x00 106 #define INSN_VSP_DEC 0x40 107 #define INSN_POP_MASKED 0x80 108 #define INSN_VSP_REG 0x90 109 #define INSN_POP_COUNT 0xa0 110 #define INSN_FINISH 0xb0 111 #define INSN_VSP_LARGE_INC 0xb2 112 113 /* An item in the exception index table */ 114 struct unwind_idx { 115 uint32_t offset; 116 uint32_t insn; 117 }; 118 119 /* The state of the unwind process */ 120 struct unwind_state { 121 uint32_t registers[16]; 122 uint32_t start_pc; 123 uint32_t *insn; 124 u_int entries; 125 u_int byte; 126 uint16_t update_mask; 127 }; 128 129 /* Expand a 31-bit signed value to a 32-bit signed value */ 130 static __inline int32_t 131 db_expand_prel31(uint32_t prel31) 132 { 133 134 return ((int32_t)(prel31 & 0x7fffffffu) << 1) / 2; 135 } 136 137 /* 138 * Perform a binary search of the index table to find the function 139 * with the largest address that doesn't exceed addr. 140 */ 141 static struct unwind_idx * 142 db_find_index(uint32_t addr) 143 { 144 unsigned int min, mid, max; 145 struct unwind_idx *start; 146 struct unwind_idx *item; 147 int32_t prel31_addr; 148 uint32_t func_addr; 149 150 start = (struct unwind_idx *)&exidx_start; 151 152 min = 0; 153 max = (&exidx_end - &exidx_start) / 2; 154 155 while (min != max) { 156 mid = min + (max - min + 1) / 2; 157 158 item = &start[mid]; 159 160 prel31_addr = db_expand_prel31(item->offset); 161 func_addr = (uint32_t)&item->offset + prel31_addr; 162 163 if (func_addr <= addr) { 164 min = mid; 165 } else { 166 max = mid - 1; 167 } 168 } 169 170 return &start[min]; 171 } 172 173 /* Reads the next byte from the instruction list */ 174 static uint8_t 175 db_unwind_exec_read_byte(struct unwind_state *state) 176 { 177 uint8_t insn; 178 179 /* Read the unwind instruction */ 180 insn = (*state->insn) >> (state->byte * 8); 181 182 /* Update the location of the next instruction */ 183 if (state->byte == 0) { 184 state->byte = 3; 185 state->insn++; 186 state->entries--; 187 } else 188 state->byte--; 189 190 return insn; 191 } 192 193 /* Executes the next instruction on the list */ 194 static int 195 db_unwind_exec_insn(struct unwind_state *state) 196 { 197 unsigned int insn; 198 uint32_t *vsp = (uint32_t *)state->registers[SP]; 199 int update_vsp = 0; 200 201 /* This should never happen */ 202 if (state->entries == 0) 203 return 1; 204 205 /* Read the next instruction */ 206 insn = db_unwind_exec_read_byte(state); 207 208 if ((insn & INSN_VSP_MASK) == INSN_VSP_INC) { 209 state->registers[SP] += ((insn & INSN_VSP_SIZE_MASK) << 2) + 4; 210 211 } else if ((insn & INSN_VSP_MASK) == INSN_VSP_DEC) { 212 state->registers[SP] -= ((insn & INSN_VSP_SIZE_MASK) << 2) + 4; 213 214 } else if ((insn & INSN_STD_MASK) == INSN_POP_MASKED) { 215 unsigned int mask, reg; 216 217 /* Load the mask */ 218 mask = db_unwind_exec_read_byte(state); 219 mask |= (insn & INSN_STD_DATA_MASK) << 8; 220 221 /* We have a refuse to unwind instruction */ 222 if (mask == 0) 223 return 1; 224 225 /* Update SP */ 226 update_vsp = 1; 227 228 /* Load the registers */ 229 for (reg = 4; mask && reg < 16; mask >>= 1, reg++) { 230 if (mask & 1) { 231 state->registers[reg] = *vsp++; 232 state->update_mask |= 1 << reg; 233 234 /* If we have updated SP kep its value */ 235 if (reg == SP) 236 update_vsp = 0; 237 } 238 } 239 240 } else if ((insn & INSN_STD_MASK) == INSN_VSP_REG && 241 ((insn & INSN_STD_DATA_MASK) != 13) && 242 ((insn & INSN_STD_DATA_MASK) != 15)) { 243 /* sp = register */ 244 state->registers[SP] = 245 state->registers[insn & INSN_STD_DATA_MASK]; 246 247 } else if ((insn & INSN_STD_MASK) == INSN_POP_COUNT) { 248 unsigned int count, reg; 249 250 /* Read how many registers to load */ 251 count = insn & INSN_POP_COUNT_MASK; 252 253 /* Update sp */ 254 update_vsp = 1; 255 256 /* Pop the registers */ 257 for (reg = 4; reg <= 4 + count; reg++) { 258 state->registers[reg] = *vsp++; 259 state->update_mask |= 1 << reg; 260 } 261 262 /* Check if we are in the pop r14 version */ 263 if ((insn & INSN_POP_TYPE_MASK) != 0) { 264 state->registers[14] = *vsp++; 265 } 266 267 } else if (insn == INSN_FINISH) { 268 /* Stop processing */ 269 state->entries = 0; 270 271 } else if ((insn & INSN_VSP_LARGE_INC_MASK) == INSN_VSP_LARGE_INC) { 272 unsigned int uleb128; 273 274 /* Read the increment value */ 275 uleb128 = db_unwind_exec_read_byte(state); 276 277 state->registers[SP] += 0x204 + (uleb128 << 2); 278 279 } else { 280 /* We hit a new instruction that needs to be implemented */ 281 db_printf("Unhandled instruction %.2x\n", insn); 282 return 1; 283 } 284 285 if (update_vsp) { 286 state->registers[SP] = (uint32_t)vsp; 287 } 288 289 #if 0 290 db_printf("fp = %08x, sp = %08x, lr = %08x, pc = %08x\n", 291 state->registers[FP], state->registers[SP], state->registers[LR], 292 state->registers[PC]); 293 #endif 294 295 return 0; 296 } 297 298 /* Performs the unwind of a function */ 299 static int 300 db_unwind_tab(struct unwind_state *state) 301 { 302 uint32_t entry; 303 304 /* Set PC to a known value */ 305 state->registers[PC] = 0; 306 307 /* Read the personality */ 308 entry = *state->insn & ENTRY_MASK; 309 310 if (entry == ENTRY_ARM_SU16) { 311 state->byte = 2; 312 state->entries = 1; 313 } else if (entry == ENTRY_ARM_LU16) { 314 state->byte = 1; 315 state->entries = ((*state->insn >> 16) & 0xFF) + 1; 316 } else { 317 db_printf("Unknown entry: %x\n", entry); 318 return 1; 319 } 320 321 while (state->entries > 0) { 322 if (db_unwind_exec_insn(state) != 0) 323 return 1; 324 } 325 326 /* 327 * The program counter was not updated, load it from the link register. 328 */ 329 if (state->registers[PC] == 0) 330 state->registers[PC] = state->registers[LR]; 331 332 return 0; 333 } 334 335 static void 336 db_stack_trace_cmd(struct unwind_state *state) 337 { 338 struct unwind_idx *index; 339 const char *name; 340 db_expr_t value; 341 db_expr_t offset; 342 c_db_sym_t sym; 343 u_int reg, i; 344 char *sep; 345 uint16_t upd_mask; 346 bool finished; 347 348 finished = false; 349 while (!finished) { 350 /* Reset the mask of updated registers */ 351 state->update_mask = 0; 352 353 /* The pc value is correct and will be overwritten, save it */ 354 state->start_pc = state->registers[PC]; 355 356 /* Find the item to run */ 357 index = db_find_index(state->start_pc); 358 359 if (index->insn != EXIDX_CANTUNWIND) { 360 if (index->insn & (1 << 31)) { 361 /* The data is within the instruction */ 362 state->insn = &index->insn; 363 } else { 364 /* A prel31 offset to the unwind table */ 365 state->insn = (uint32_t *) 366 ((uintptr_t)&index->insn + 367 db_expand_prel31(index->insn)); 368 } 369 /* Run the unwind function */ 370 finished = db_unwind_tab(state); 371 } 372 373 /* Print the frame details */ 374 sym = db_search_symbol(state->start_pc, DB_STGY_ANY, &offset); 375 if (sym == C_DB_SYM_NULL) { 376 value = 0; 377 name = "(null)"; 378 } else 379 db_symbol_values(sym, &name, &value); 380 db_printf("%s() at ", name); 381 db_printsym(state->start_pc, DB_STGY_PROC); 382 db_printf("\n"); 383 db_printf("\t pc = 0x%08x lr = 0x%08x (", state->start_pc, 384 state->registers[LR]); 385 db_printsym(state->registers[LR], DB_STGY_PROC); 386 db_printf(")\n"); 387 db_printf("\t sp = 0x%08x fp = 0x%08x", 388 state->registers[SP], state->registers[FP]); 389 390 /* Don't print the registers we have already printed */ 391 upd_mask = state->update_mask & 392 ~((1 << SP) | (1 << FP) | (1 << LR) | (1 << PC)); 393 sep = "\n\t"; 394 for (i = 0, reg = 0; upd_mask != 0; upd_mask >>= 1, reg++) { 395 if ((upd_mask & 1) != 0) { 396 db_printf("%s%sr%d = 0x%08x", sep, 397 (reg < 10) ? " " : "", reg, 398 state->registers[reg]); 399 i++; 400 if (i == 2) { 401 sep = "\n\t"; 402 i = 0; 403 } else 404 sep = " "; 405 406 } 407 } 408 db_printf("\n"); 409 410 /* 411 * Stop if directed to do so, or if we've unwound back to the 412 * kernel entry point, or if the unwind function didn't change 413 * anything (to avoid getting stuck in this loop forever). 414 * If the latter happens, it's an indication that the unwind 415 * information is incorrect somehow for the function named in 416 * the last frame printed before you see the unwind failure 417 * message (maybe it needs a STOP_UNWINDING). 418 */ 419 if (index->insn == EXIDX_CANTUNWIND) { 420 db_printf("Unable to unwind further\n"); 421 finished = true; 422 } else if (state->registers[PC] < VM_MIN_KERNEL_ADDRESS) { 423 db_printf("Unable to unwind into user mode\n"); 424 finished = true; 425 } else if (state->update_mask == 0) { 426 db_printf("Unwind failure (no registers changed)\n"); 427 finished = true; 428 } 429 } 430 } 431 #endif 432 433 /* 434 * APCS stack frames are awkward beasts, so I don't think even trying to use 435 * a structure to represent them is a good idea. 436 * 437 * Here's the diagram from the APCS. Increasing address is _up_ the page. 438 * 439 * save code pointer [fp] <- fp points to here 440 * return link value [fp, #-4] 441 * return sp value [fp, #-8] 442 * return fp value [fp, #-12] 443 * [saved v7 value] 444 * [saved v6 value] 445 * [saved v5 value] 446 * [saved v4 value] 447 * [saved v3 value] 448 * [saved v2 value] 449 * [saved v1 value] 450 * [saved a4 value] 451 * [saved a3 value] 452 * [saved a2 value] 453 * [saved a1 value] 454 * 455 * The save code pointer points twelve bytes beyond the start of the 456 * code sequence (usually a single STM) that created the stack frame. 457 * We have to disassemble it if we want to know which of the optional 458 * fields are actually present. 459 */ 460 461 #ifndef __ARM_EABI__ /* The frame format is differend in AAPCS */ 462 static void 463 db_stack_trace_cmd(db_expr_t addr, db_expr_t count, boolean_t kernel_only) 464 { 465 u_int32_t *frame, *lastframe; 466 c_db_sym_t sym; 467 const char *name; 468 db_expr_t value; 469 db_expr_t offset; 470 int scp_offset; 471 472 frame = (u_int32_t *)addr; 473 lastframe = NULL; 474 scp_offset = -(get_pc_str_offset() >> 2); 475 476 while (count-- && frame != NULL && !db_pager_quit) { 477 db_addr_t scp; 478 u_int32_t savecode; 479 int r; 480 u_int32_t *rp; 481 const char *sep; 482 483 /* 484 * In theory, the SCP isn't guaranteed to be in the function 485 * that generated the stack frame. We hope for the best. 486 */ 487 scp = frame[FR_SCP]; 488 489 sym = db_search_symbol(scp, DB_STGY_ANY, &offset); 490 if (sym == C_DB_SYM_NULL) { 491 value = 0; 492 name = "(null)"; 493 } else 494 db_symbol_values(sym, &name, &value); 495 db_printf("%s() at ", name); 496 db_printsym(scp, DB_STGY_PROC); 497 db_printf("\n"); 498 #ifdef __PROG26 499 db_printf("scp=0x%08x rlv=0x%08x (", scp, frame[FR_RLV] & R15_PC); 500 db_printsym(frame[FR_RLV] & R15_PC, DB_STGY_PROC); 501 db_printf(")\n"); 502 #else 503 db_printf("scp=0x%08x rlv=0x%08x (", scp, frame[FR_RLV]); 504 db_printsym(frame[FR_RLV], DB_STGY_PROC); 505 db_printf(")\n"); 506 #endif 507 db_printf("\trsp=0x%08x rfp=0x%08x", frame[FR_RSP], frame[FR_RFP]); 508 509 savecode = ((u_int32_t *)scp)[scp_offset]; 510 if ((savecode & 0x0e100000) == 0x08000000) { 511 /* Looks like an STM */ 512 rp = frame - 4; 513 sep = "\n\t"; 514 for (r = 10; r >= 0; r--) { 515 if (savecode & (1 << r)) { 516 db_printf("%sr%d=0x%08x", 517 sep, r, *rp--); 518 sep = (frame - rp) % 4 == 2 ? 519 "\n\t" : " "; 520 } 521 } 522 } 523 524 db_printf("\n"); 525 526 /* 527 * Switch to next frame up 528 */ 529 if (frame[FR_RFP] == 0) 530 break; /* Top of stack */ 531 532 lastframe = frame; 533 frame = (u_int32_t *)(frame[FR_RFP]); 534 535 if (INKERNEL((int)frame)) { 536 /* staying in kernel */ 537 if (frame <= lastframe) { 538 db_printf("Bad frame pointer: %p\n", frame); 539 break; 540 } 541 } else if (INKERNEL((int)lastframe)) { 542 /* switch from user to kernel */ 543 if (kernel_only) 544 break; /* kernel stack only */ 545 } else { 546 /* in user */ 547 if (frame <= lastframe) { 548 db_printf("Bad user frame pointer: %p\n", 549 frame); 550 break; 551 } 552 } 553 } 554 } 555 #endif 556 557 /* XXX stubs */ 558 void 559 db_md_list_watchpoints() 560 { 561 } 562 563 int 564 db_md_clr_watchpoint(db_expr_t addr, db_expr_t size) 565 { 566 return (0); 567 } 568 569 int 570 db_md_set_watchpoint(db_expr_t addr, db_expr_t size) 571 { 572 return (0); 573 } 574 575 int 576 db_trace_thread(struct thread *thr, int count) 577 { 578 #ifdef __ARM_EABI__ 579 struct unwind_state state; 580 #endif 581 struct pcb *ctx; 582 583 if (thr != curthread) { 584 ctx = kdb_thr_ctx(thr); 585 586 #ifdef __ARM_EABI__ 587 state.registers[FP] = ctx->un_32.pcb32_r11; 588 state.registers[SP] = ctx->un_32.pcb32_sp; 589 state.registers[LR] = ctx->un_32.pcb32_lr; 590 state.registers[PC] = ctx->un_32.pcb32_pc; 591 592 db_stack_trace_cmd(&state); 593 #else 594 db_stack_trace_cmd(ctx->un_32.pcb32_r11, -1, TRUE); 595 #endif 596 } else 597 db_trace_self(); 598 return (0); 599 } 600 601 void 602 db_trace_self(void) 603 { 604 #ifdef __ARM_EABI__ 605 struct unwind_state state; 606 uint32_t sp; 607 608 /* Read the stack pointer */ 609 __asm __volatile("mov %0, sp" : "=&r" (sp)); 610 611 state.registers[FP] = (uint32_t)__builtin_frame_address(0); 612 state.registers[SP] = sp; 613 state.registers[LR] = (uint32_t)__builtin_return_address(0); 614 state.registers[PC] = (uint32_t)db_trace_self; 615 616 db_stack_trace_cmd(&state); 617 #else 618 db_addr_t addr; 619 620 addr = (db_addr_t)__builtin_frame_address(0); 621 db_stack_trace_cmd(addr, -1, FALSE); 622 #endif 623 } 624