Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/amd64/amd64/db_trace.c
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1 /*- 2 * Mach Operating System 3 * Copyright (c) 1991,1990 Carnegie Mellon University 4 * All Rights Reserved. 5 * 6 * Permission to use, copy, modify and distribute this software and its 7 * documentation is hereby granted, provided that both the copyright 8 * notice and this permission notice appear in all copies of the 9 * software, derivative works or modified versions, and any portions 10 * thereof, and that both notices appear in supporting documentation. 11 * 12 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS 13 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR 14 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 15 * 16 * Carnegie Mellon requests users of this software to return to 17 * 18 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 19 * School of Computer Science 20 * Carnegie Mellon University 21 * Pittsburgh PA 15213-3890 22 * 23 * any improvements or extensions that they make and grant Carnegie the 24 * rights to redistribute these changes. 25 */ 26 27 #include <sys/cdefs.h> 28 __FBSDID("$FreeBSD: releng/11.2/sys/amd64/amd64/db_trace.c 330587 2018-03-07 13:37:25Z avg $"); 29 30 #include "opt_compat.h" 31 32 #include <sys/param.h> 33 #include <sys/systm.h> 34 #include <sys/kdb.h> 35 #include <sys/proc.h> 36 #include <sys/smp.h> 37 #include <sys/stack.h> 38 #include <sys/sysent.h> 39 40 #include <machine/cpu.h> 41 #include <machine/md_var.h> 42 #include <machine/pcb.h> 43 #include <machine/reg.h> 44 #include <machine/stack.h> 45 46 #include <vm/vm.h> 47 #include <vm/vm_param.h> 48 #include <vm/pmap.h> 49 50 #include <ddb/ddb.h> 51 #include <ddb/db_access.h> 52 #include <ddb/db_sym.h> 53 #include <ddb/db_variables.h> 54 55 static db_varfcn_t db_frame; 56 static db_varfcn_t db_frame_seg; 57 58 CTASSERT(sizeof(struct dbreg) == sizeof(((struct pcpu *)NULL)->pc_dbreg)); 59 60 /* 61 * Machine register set. 62 */ 63 #define DB_OFFSET(x) (db_expr_t *)offsetof(struct trapframe, x) 64 struct db_variable db_regs[] = { 65 { "cs", DB_OFFSET(tf_cs), db_frame_seg }, 66 { "ds", DB_OFFSET(tf_ds), db_frame_seg }, 67 { "es", DB_OFFSET(tf_es), db_frame_seg }, 68 { "fs", DB_OFFSET(tf_fs), db_frame_seg }, 69 { "gs", DB_OFFSET(tf_gs), db_frame_seg }, 70 { "ss", DB_OFFSET(tf_ss), db_frame_seg }, 71 { "rax", DB_OFFSET(tf_rax), db_frame }, 72 { "rcx", DB_OFFSET(tf_rcx), db_frame }, 73 { "rdx", DB_OFFSET(tf_rdx), db_frame }, 74 { "rbx", DB_OFFSET(tf_rbx), db_frame }, 75 { "rsp", DB_OFFSET(tf_rsp), db_frame }, 76 { "rbp", DB_OFFSET(tf_rbp), db_frame }, 77 { "rsi", DB_OFFSET(tf_rsi), db_frame }, 78 { "rdi", DB_OFFSET(tf_rdi), db_frame }, 79 { "r8", DB_OFFSET(tf_r8), db_frame }, 80 { "r9", DB_OFFSET(tf_r9), db_frame }, 81 { "r10", DB_OFFSET(tf_r10), db_frame }, 82 { "r11", DB_OFFSET(tf_r11), db_frame }, 83 { "r12", DB_OFFSET(tf_r12), db_frame }, 84 { "r13", DB_OFFSET(tf_r13), db_frame }, 85 { "r14", DB_OFFSET(tf_r14), db_frame }, 86 { "r15", DB_OFFSET(tf_r15), db_frame }, 87 { "rip", DB_OFFSET(tf_rip), db_frame }, 88 { "rflags", DB_OFFSET(tf_rflags), db_frame }, 89 }; 90 struct db_variable *db_eregs = db_regs + nitems(db_regs); 91 92 static int 93 db_frame_seg(struct db_variable *vp, db_expr_t *valuep, int op) 94 { 95 uint16_t *reg; 96 97 if (kdb_frame == NULL) 98 return (0); 99 100 reg = (uint16_t *)((uintptr_t)kdb_frame + (db_expr_t)vp->valuep); 101 if (op == DB_VAR_GET) 102 *valuep = *reg; 103 else 104 *reg = *valuep; 105 return (1); 106 } 107 108 static int 109 db_frame(struct db_variable *vp, db_expr_t *valuep, int op) 110 { 111 long *reg; 112 113 if (kdb_frame == NULL) 114 return (0); 115 116 reg = (long *)((uintptr_t)kdb_frame + (db_expr_t)vp->valuep); 117 if (op == DB_VAR_GET) 118 *valuep = *reg; 119 else 120 *reg = *valuep; 121 return (1); 122 } 123 124 #define NORMAL 0 125 #define TRAP 1 126 #define INTERRUPT 2 127 #define SYSCALL 3 128 #define TRAP_INTERRUPT 5 129 130 static void db_nextframe(struct amd64_frame **, db_addr_t *, struct thread *); 131 static void db_print_stack_entry(const char *, db_addr_t, void *); 132 static void decode_syscall(int, struct thread *); 133 134 static const char * watchtype_str(int type); 135 int amd64_set_watch(int watchnum, unsigned long watchaddr, int size, 136 int access, struct dbreg *d); 137 int amd64_clr_watch(int watchnum, struct dbreg *d); 138 139 static void 140 db_print_stack_entry(const char *name, db_addr_t callpc, void *frame) 141 { 142 143 db_printf("%s() at ", name != NULL ? name : "??"); 144 db_printsym(callpc, DB_STGY_PROC); 145 if (frame != NULL) 146 db_printf("/frame 0x%lx", (register_t)frame); 147 db_printf("\n"); 148 } 149 150 static void 151 decode_syscall(int number, struct thread *td) 152 { 153 struct proc *p; 154 c_db_sym_t sym; 155 db_expr_t diff; 156 sy_call_t *f; 157 const char *symname; 158 159 db_printf(" (%d", number); 160 p = (td != NULL) ? td->td_proc : NULL; 161 if (p != NULL && 0 <= number && number < p->p_sysent->sv_size) { 162 f = p->p_sysent->sv_table[number].sy_call; 163 sym = db_search_symbol((db_addr_t)f, DB_STGY_ANY, &diff); 164 if (sym != DB_SYM_NULL && diff == 0) { 165 db_symbol_values(sym, &symname, NULL); 166 db_printf(", %s, %s", p->p_sysent->sv_name, symname); 167 } 168 } 169 db_printf(")"); 170 } 171 172 /* 173 * Figure out the next frame up in the call stack. 174 */ 175 static void 176 db_nextframe(struct amd64_frame **fp, db_addr_t *ip, struct thread *td) 177 { 178 struct trapframe *tf; 179 int frame_type; 180 long rip, rsp, rbp; 181 db_expr_t offset; 182 c_db_sym_t sym; 183 const char *name; 184 185 rip = db_get_value((long) &(*fp)->f_retaddr, 8, FALSE); 186 rbp = db_get_value((long) &(*fp)->f_frame, 8, FALSE); 187 188 /* 189 * Figure out frame type. We look at the address just before 190 * the saved instruction pointer as the saved EIP is after the 191 * call function, and if the function being called is marked as 192 * dead (such as panic() at the end of dblfault_handler()), then 193 * the instruction at the saved EIP will be part of a different 194 * function (syscall() in this example) rather than the one that 195 * actually made the call. 196 */ 197 frame_type = NORMAL; 198 sym = db_search_symbol(rip - 1, DB_STGY_ANY, &offset); 199 db_symbol_values(sym, &name, NULL); 200 if (name != NULL) { 201 if (strcmp(name, "calltrap") == 0 || 202 strcmp(name, "fork_trampoline") == 0 || 203 strcmp(name, "mchk_calltrap") == 0 || 204 strcmp(name, "nmi_calltrap") == 0 || 205 strcmp(name, "Xdblfault") == 0) 206 frame_type = TRAP; 207 else if (strncmp(name, "Xatpic_intr", 11) == 0 || 208 strncmp(name, "Xapic_isr", 9) == 0 || 209 strcmp(name, "Xtimerint") == 0 || 210 strcmp(name, "Xipi_intr_bitmap_handler") == 0 || 211 strcmp(name, "Xcpustop") == 0 || 212 strcmp(name, "Xcpususpend") == 0 || 213 strcmp(name, "Xrendezvous") == 0) 214 frame_type = INTERRUPT; 215 else if (strcmp(name, "Xfast_syscall") == 0 || 216 strcmp(name, "Xfast_syscall_pti") == 0 || 217 strcmp(name, "fast_syscall_common") == 0) 218 frame_type = SYSCALL; 219 #ifdef COMPAT_FREEBSD32 220 else if (strcmp(name, "Xint0x80_syscall") == 0) 221 frame_type = SYSCALL; 222 #endif 223 /* XXX: These are interrupts with trap frames. */ 224 else if (strcmp(name, "Xtimerint") == 0 || 225 strcmp(name, "Xcpustop") == 0 || 226 strcmp(name, "Xcpususpend") == 0 || 227 strcmp(name, "Xrendezvous") == 0 || 228 strcmp(name, "Xipi_intr_bitmap_handler") == 0) 229 frame_type = TRAP_INTERRUPT; 230 } 231 232 /* 233 * Normal frames need no special processing. 234 */ 235 if (frame_type == NORMAL) { 236 *ip = (db_addr_t) rip; 237 *fp = (struct amd64_frame *) rbp; 238 return; 239 } 240 241 db_print_stack_entry(name, rip, &(*fp)->f_frame); 242 243 /* 244 * Point to base of trapframe which is just above the 245 * current frame. 246 */ 247 tf = (struct trapframe *)((long)*fp + 16); 248 249 if (INKERNEL((long) tf)) { 250 rsp = tf->tf_rsp; 251 rip = tf->tf_rip; 252 rbp = tf->tf_rbp; 253 switch (frame_type) { 254 case TRAP: 255 db_printf("--- trap %#r", tf->tf_trapno); 256 break; 257 case SYSCALL: 258 db_printf("--- syscall"); 259 decode_syscall(tf->tf_rax, td); 260 break; 261 case TRAP_INTERRUPT: 262 case INTERRUPT: 263 db_printf("--- interrupt"); 264 break; 265 default: 266 panic("The moon has moved again."); 267 } 268 db_printf(", rip = %#lr, rsp = %#lr, rbp = %#lr ---\n", rip, 269 rsp, rbp); 270 } 271 272 *ip = (db_addr_t) rip; 273 *fp = (struct amd64_frame *) rbp; 274 } 275 276 static int 277 db_backtrace(struct thread *td, struct trapframe *tf, struct amd64_frame *frame, 278 db_addr_t pc, register_t sp, int count) 279 { 280 struct amd64_frame *actframe; 281 const char *name; 282 db_expr_t offset; 283 c_db_sym_t sym; 284 boolean_t first; 285 286 if (count == -1) 287 count = 1024; 288 289 first = TRUE; 290 while (count-- && !db_pager_quit) { 291 sym = db_search_symbol(pc, DB_STGY_ANY, &offset); 292 db_symbol_values(sym, &name, NULL); 293 294 /* 295 * Attempt to determine a (possibly fake) frame that gives 296 * the caller's pc. It may differ from `frame' if the 297 * current function never sets up a standard frame or hasn't 298 * set one up yet or has just discarded one. The last two 299 * cases can be guessed fairly reliably for code generated 300 * by gcc. The first case is too much trouble to handle in 301 * general because the amount of junk on the stack depends 302 * on the pc (the special handling of "calltrap", etc. in 303 * db_nextframe() works because the `next' pc is special). 304 */ 305 actframe = frame; 306 if (first) { 307 first = FALSE; 308 if (sym == C_DB_SYM_NULL && sp != 0) { 309 /* 310 * If a symbol couldn't be found, we've probably 311 * jumped to a bogus location, so try and use 312 * the return address to find our caller. 313 */ 314 db_print_stack_entry(name, pc, NULL); 315 pc = db_get_value(sp, 8, FALSE); 316 if (db_search_symbol(pc, DB_STGY_PROC, 317 &offset) == C_DB_SYM_NULL) 318 break; 319 continue; 320 } else if (tf != NULL) { 321 int instr; 322 323 instr = db_get_value(pc, 4, FALSE); 324 if ((instr & 0xffffffff) == 0xe5894855) { 325 /* pushq %rbp; movq %rsp, %rbp */ 326 actframe = (void *)(tf->tf_rsp - 8); 327 } else if ((instr & 0xffffff) == 0xe58948) { 328 /* movq %rsp, %rbp */ 329 actframe = (void *)tf->tf_rsp; 330 if (tf->tf_rbp == 0) { 331 /* Fake frame better. */ 332 frame = actframe; 333 } 334 } else if ((instr & 0xff) == 0xc3) { 335 /* ret */ 336 actframe = (void *)(tf->tf_rsp - 8); 337 } else if (offset == 0) { 338 /* Probably an assembler symbol. */ 339 actframe = (void *)(tf->tf_rsp - 8); 340 } 341 } else if (name != NULL && 342 strcmp(name, "fork_trampoline") == 0) { 343 /* 344 * Don't try to walk back on a stack for a 345 * process that hasn't actually been run yet. 346 */ 347 db_print_stack_entry(name, pc, actframe); 348 break; 349 } 350 } 351 352 db_print_stack_entry(name, pc, actframe); 353 354 if (actframe != frame) { 355 /* `frame' belongs to caller. */ 356 pc = (db_addr_t) 357 db_get_value((long)&actframe->f_retaddr, 8, FALSE); 358 continue; 359 } 360 361 db_nextframe(&frame, &pc, td); 362 363 if (INKERNEL((long)pc) && !INKERNEL((long)frame)) { 364 sym = db_search_symbol(pc, DB_STGY_ANY, &offset); 365 db_symbol_values(sym, &name, NULL); 366 db_print_stack_entry(name, pc, frame); 367 break; 368 } 369 if (!INKERNEL((long) frame)) { 370 break; 371 } 372 } 373 374 return (0); 375 } 376 377 void 378 db_trace_self(void) 379 { 380 struct amd64_frame *frame; 381 db_addr_t callpc; 382 register_t rbp; 383 384 __asm __volatile("movq %%rbp,%0" : "=r" (rbp)); 385 frame = (struct amd64_frame *)rbp; 386 callpc = (db_addr_t)db_get_value((long)&frame->f_retaddr, 8, FALSE); 387 frame = frame->f_frame; 388 db_backtrace(curthread, NULL, frame, callpc, 0, -1); 389 } 390 391 int 392 db_trace_thread(struct thread *thr, int count) 393 { 394 struct pcb *ctx; 395 struct trapframe *tf; 396 397 ctx = kdb_thr_ctx(thr); 398 tf = thr == kdb_thread ? kdb_frame : NULL; 399 return (db_backtrace(thr, tf, (struct amd64_frame *)ctx->pcb_rbp, 400 ctx->pcb_rip, ctx->pcb_rsp, count)); 401 } 402 403 int 404 amd64_set_watch(watchnum, watchaddr, size, access, d) 405 int watchnum; 406 unsigned long watchaddr; 407 int size; 408 int access; 409 struct dbreg *d; 410 { 411 int i, len; 412 413 if (watchnum == -1) { 414 for (i = 0; i < 4; i++) 415 if (!DBREG_DR7_ENABLED(d->dr[7], i)) 416 break; 417 if (i < 4) 418 watchnum = i; 419 else 420 return (-1); 421 } 422 423 switch (access) { 424 case DBREG_DR7_EXEC: 425 size = 1; /* size must be 1 for an execution breakpoint */ 426 /* fall through */ 427 case DBREG_DR7_WRONLY: 428 case DBREG_DR7_RDWR: 429 break; 430 default: 431 return (-1); 432 } 433 434 /* 435 * we can watch a 1, 2, 4, or 8 byte sized location 436 */ 437 switch (size) { 438 case 1: 439 len = DBREG_DR7_LEN_1; 440 break; 441 case 2: 442 len = DBREG_DR7_LEN_2; 443 break; 444 case 4: 445 len = DBREG_DR7_LEN_4; 446 break; 447 case 8: 448 len = DBREG_DR7_LEN_8; 449 break; 450 default: 451 return (-1); 452 } 453 454 /* clear the bits we are about to affect */ 455 d->dr[7] &= ~DBREG_DR7_MASK(watchnum); 456 457 /* set drN register to the address, N=watchnum */ 458 DBREG_DRX(d, watchnum) = watchaddr; 459 460 /* enable the watchpoint */ 461 d->dr[7] |= DBREG_DR7_SET(watchnum, len, access, 462 DBREG_DR7_GLOBAL_ENABLE); 463 464 return (watchnum); 465 } 466 467 468 int 469 amd64_clr_watch(watchnum, d) 470 int watchnum; 471 struct dbreg *d; 472 { 473 474 if (watchnum < 0 || watchnum >= 4) 475 return (-1); 476 477 d->dr[7] &= ~DBREG_DR7_MASK(watchnum); 478 DBREG_DRX(d, watchnum) = 0; 479 480 return (0); 481 } 482 483 484 int 485 db_md_set_watchpoint(addr, size) 486 db_expr_t addr; 487 db_expr_t size; 488 { 489 struct dbreg *d; 490 struct pcpu *pc; 491 int avail, c, cpu, i, wsize; 492 493 d = (struct dbreg *)PCPU_PTR(dbreg); 494 cpu = PCPU_GET(cpuid); 495 fill_dbregs(NULL, d); 496 497 avail = 0; 498 for (i = 0; i < 4; i++) { 499 if (!DBREG_DR7_ENABLED(d->dr[7], i)) 500 avail++; 501 } 502 503 if (avail * 8 < size) 504 return (-1); 505 506 for (i = 0; i < 4 && size > 0; i++) { 507 if (!DBREG_DR7_ENABLED(d->dr[7], i)) { 508 if (size >= 8 || (avail == 1 && size > 4)) 509 wsize = 8; 510 else if (size > 2) 511 wsize = 4; 512 else 513 wsize = size; 514 amd64_set_watch(i, addr, wsize, DBREG_DR7_WRONLY, d); 515 addr += wsize; 516 size -= wsize; 517 avail--; 518 } 519 } 520 521 set_dbregs(NULL, d); 522 CPU_FOREACH(c) { 523 if (c == cpu) 524 continue; 525 pc = pcpu_find(c); 526 memcpy(pc->pc_dbreg, d, sizeof(*d)); 527 pc->pc_dbreg_cmd = PC_DBREG_CMD_LOAD; 528 } 529 530 return (0); 531 } 532 533 int 534 db_md_clr_watchpoint(addr, size) 535 db_expr_t addr; 536 db_expr_t size; 537 { 538 struct dbreg *d; 539 struct pcpu *pc; 540 int i, c, cpu; 541 542 d = (struct dbreg *)PCPU_PTR(dbreg); 543 cpu = PCPU_GET(cpuid); 544 fill_dbregs(NULL, d); 545 546 for (i = 0; i < 4; i++) { 547 if (DBREG_DR7_ENABLED(d->dr[7], i)) { 548 if (DBREG_DRX((d), i) >= addr && 549 DBREG_DRX((d), i) < addr + size) 550 amd64_clr_watch(i, d); 551 552 } 553 } 554 555 set_dbregs(NULL, d); 556 CPU_FOREACH(c) { 557 if (c == cpu) 558 continue; 559 pc = pcpu_find(c); 560 memcpy(pc->pc_dbreg, d, sizeof(*d)); 561 pc->pc_dbreg_cmd = PC_DBREG_CMD_LOAD; 562 } 563 564 return (0); 565 } 566 567 568 static const char * 569 watchtype_str(type) 570 int type; 571 { 572 switch (type) { 573 case DBREG_DR7_EXEC : return "execute"; break; 574 case DBREG_DR7_RDWR : return "read/write"; break; 575 case DBREG_DR7_WRONLY : return "write"; break; 576 default : return "invalid"; break; 577 } 578 } 579 580 581 void 582 db_md_list_watchpoints() 583 { 584 struct dbreg d; 585 int i, len, type; 586 587 fill_dbregs(NULL, &d); 588 589 db_printf("\nhardware watchpoints:\n"); 590 db_printf(" watch status type len address\n"); 591 db_printf(" ----- -------- ---------- --- ------------------\n"); 592 for (i = 0; i < 4; i++) { 593 if (DBREG_DR7_ENABLED(d.dr[7], i)) { 594 type = DBREG_DR7_ACCESS(d.dr[7], i); 595 len = DBREG_DR7_LEN(d.dr[7], i); 596 if (len == DBREG_DR7_LEN_8) 597 len = 8; 598 else 599 len++; 600 db_printf(" %-5d %-8s %10s %3d ", 601 i, "enabled", watchtype_str(type), len); 602 db_printsym((db_addr_t)DBREG_DRX((&d), i), DB_STGY_ANY); 603 db_printf("\n"); 604 } else { 605 db_printf(" %-5d disabled\n", i); 606 } 607 } 608 609 db_printf("\ndebug register values:\n"); 610 for (i = 0; i < 8; i++) { 611 db_printf(" dr%d 0x%016lx\n", i, DBREG_DRX((&d), i)); 612 } 613 db_printf("\n"); 614 } 615 616 void 617 amd64_db_resume_dbreg(void) 618 { 619 struct dbreg *d; 620 621 switch (PCPU_GET(dbreg_cmd)) { 622 case PC_DBREG_CMD_LOAD: 623 d = (struct dbreg *)PCPU_PTR(dbreg); 624 set_dbregs(NULL, d); 625 PCPU_SET(dbreg_cmd, PC_DBREG_CMD_NONE); 626 break; 627 } 628 }
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