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("$FreeBSD$"); 29 30 #include <sys/param.h> 31 #include <sys/systm.h> 32 #include <sys/kdb.h> 33 #include <sys/proc.h> 34 #include <sys/reg.h> 35 36 #include <machine/cpu.h> 37 #include <machine/frame.h> 38 #include <machine/md_var.h> 39 #include <machine/pcb.h> 40 #include <machine/stack.h> 41 42 #include <vm/vm.h> 43 #include <vm/vm_param.h> 44 #include <vm/pmap.h> 45 46 #include <ddb/ddb.h> 47 #include <ddb/db_access.h> 48 #include <ddb/db_sym.h> 49 #include <ddb/db_variables.h> 50 51 static db_varfcn_t db_esp; 52 static db_varfcn_t db_frame; 53 static db_varfcn_t db_frame_seg; 54 static db_varfcn_t db_gs; 55 static db_varfcn_t db_ss; 56 57 /* 58 * Machine register set. 59 */ 60 #define DB_OFFSET(x) (db_expr_t *)offsetof(struct trapframe, x) 61 struct db_variable db_regs[] = { 62 { "cs", DB_OFFSET(tf_cs), db_frame_seg }, 63 { "ds", DB_OFFSET(tf_ds), db_frame_seg }, 64 { "es", DB_OFFSET(tf_es), db_frame_seg }, 65 { "fs", DB_OFFSET(tf_fs), db_frame_seg }, 66 { "gs", NULL, db_gs }, 67 { "ss", NULL, db_ss }, 68 { "eax", DB_OFFSET(tf_eax), db_frame }, 69 { "ecx", DB_OFFSET(tf_ecx), db_frame }, 70 { "edx", DB_OFFSET(tf_edx), db_frame }, 71 { "ebx", DB_OFFSET(tf_ebx), db_frame }, 72 { "esp", NULL, db_esp }, 73 { "ebp", DB_OFFSET(tf_ebp), db_frame }, 74 { "esi", DB_OFFSET(tf_esi), db_frame }, 75 { "edi", DB_OFFSET(tf_edi), db_frame }, 76 { "eip", DB_OFFSET(tf_eip), db_frame }, 77 { "efl", DB_OFFSET(tf_eflags), db_frame }, 78 }; 79 struct db_variable *db_eregs = db_regs + nitems(db_regs); 80 81 static __inline int 82 get_esp(struct trapframe *tf) 83 { 84 return (TF_HAS_STACKREGS(tf) ? tf->tf_esp : (intptr_t)&tf->tf_esp); 85 } 86 87 static int 88 db_frame(struct db_variable *vp, db_expr_t *valuep, int op) 89 { 90 int *reg; 91 92 if (kdb_frame == NULL) 93 return (0); 94 95 reg = (int *)((uintptr_t)kdb_frame + (db_expr_t)vp->valuep); 96 if (op == DB_VAR_GET) 97 *valuep = *reg; 98 else 99 *reg = *valuep; 100 return (1); 101 } 102 103 static int 104 db_frame_seg(struct db_variable *vp, db_expr_t *valuep, int op) 105 { 106 struct trapframe_vm86 *tfp; 107 int off; 108 uint16_t *reg; 109 110 if (kdb_frame == NULL) 111 return (0); 112 113 off = (intptr_t)vp->valuep; 114 if (kdb_frame->tf_eflags & PSL_VM) { 115 tfp = (void *)kdb_frame; 116 switch ((intptr_t)vp->valuep) { 117 case (intptr_t)DB_OFFSET(tf_cs): 118 reg = (uint16_t *)&tfp->tf_cs; 119 break; 120 case (intptr_t)DB_OFFSET(tf_ds): 121 reg = (uint16_t *)&tfp->tf_vm86_ds; 122 break; 123 case (intptr_t)DB_OFFSET(tf_es): 124 reg = (uint16_t *)&tfp->tf_vm86_es; 125 break; 126 case (intptr_t)DB_OFFSET(tf_fs): 127 reg = (uint16_t *)&tfp->tf_vm86_fs; 128 break; 129 } 130 } else 131 reg = (uint16_t *)((uintptr_t)kdb_frame + off); 132 if (op == DB_VAR_GET) 133 *valuep = *reg; 134 else 135 *reg = *valuep; 136 return (1); 137 } 138 139 static int 140 db_esp(struct db_variable *vp, db_expr_t *valuep, int op) 141 { 142 143 if (kdb_frame == NULL) 144 return (0); 145 146 if (op == DB_VAR_GET) 147 *valuep = get_esp(kdb_frame); 148 else if (TF_HAS_STACKREGS(kdb_frame)) 149 kdb_frame->tf_esp = *valuep; 150 return (1); 151 } 152 153 static int 154 db_gs(struct db_variable *vp, db_expr_t *valuep, int op) 155 { 156 struct trapframe_vm86 *tfp; 157 158 if (kdb_frame != NULL && kdb_frame->tf_eflags & PSL_VM) { 159 tfp = (void *)kdb_frame; 160 if (op == DB_VAR_GET) 161 *valuep = tfp->tf_vm86_gs; 162 else 163 tfp->tf_vm86_gs = *valuep; 164 return (1); 165 } 166 if (op == DB_VAR_GET) 167 *valuep = rgs(); 168 else 169 load_gs(*valuep); 170 return (1); 171 } 172 173 static int 174 db_ss(struct db_variable *vp, db_expr_t *valuep, int op) 175 { 176 177 if (kdb_frame == NULL) 178 return (0); 179 180 if (op == DB_VAR_GET) 181 *valuep = TF_HAS_STACKREGS(kdb_frame) ? kdb_frame->tf_ss : 182 rss(); 183 else if (TF_HAS_STACKREGS(kdb_frame)) 184 kdb_frame->tf_ss = *valuep; 185 return (1); 186 } 187 188 #define NORMAL 0 189 #define TRAP 1 190 #define INTERRUPT 2 191 #define SYSCALL 3 192 #define DOUBLE_FAULT 4 193 194 static void db_nextframe(struct i386_frame **, db_addr_t *, struct thread *); 195 static int db_numargs(struct i386_frame *); 196 static void db_print_stack_entry(const char *, int, char **, int *, db_addr_t, 197 void *); 198 199 /* 200 * Figure out how many arguments were passed into the frame at "fp". 201 */ 202 static int 203 db_numargs(struct i386_frame *fp) 204 { 205 char *argp; 206 int inst; 207 int args; 208 209 argp = (char *)db_get_value((int)&fp->f_retaddr, 4, false); 210 /* 211 * XXX etext is wrong for LKMs. We should attempt to interpret 212 * the instruction at the return address in all cases. This 213 * may require better fault handling. 214 */ 215 if (argp < btext || argp >= etext) { 216 args = -1; 217 } else { 218 retry: 219 inst = db_get_value((int)argp, 4, false); 220 if ((inst & 0xff) == 0x59) /* popl %ecx */ 221 args = 1; 222 else if ((inst & 0xffff) == 0xc483) /* addl $Ibs, %esp */ 223 args = ((inst >> 16) & 0xff) / 4; 224 else if ((inst & 0xf8ff) == 0xc089) { /* movl %eax, %Reg */ 225 argp += 2; 226 goto retry; 227 } else 228 args = -1; 229 } 230 return (args); 231 } 232 233 static void 234 db_print_stack_entry(const char *name, int narg, char **argnp, int *argp, 235 db_addr_t callpc, void *frame) 236 { 237 int n = narg >= 0 ? narg : 5; 238 239 db_printf("%s(", name); 240 while (n) { 241 if (argnp) 242 db_printf("%s=", *argnp++); 243 db_printf("%r", db_get_value((int)argp, 4, false)); 244 argp++; 245 if (--n != 0) 246 db_printf(","); 247 } 248 if (narg < 0) 249 db_printf(",..."); 250 db_printf(") at "); 251 db_printsym(callpc, DB_STGY_PROC); 252 if (frame != NULL) 253 db_printf("/frame 0x%r", (register_t)frame); 254 db_printf("\n"); 255 } 256 257 /* 258 * Figure out the next frame up in the call stack. 259 */ 260 static void 261 db_nextframe(struct i386_frame **fp, db_addr_t *ip, struct thread *td) 262 { 263 struct trapframe *tf; 264 int frame_type; 265 int eip, esp, ebp; 266 db_expr_t offset; 267 c_db_sym_t sym; 268 const char *name; 269 270 eip = db_get_value((int) &(*fp)->f_retaddr, 4, false); 271 ebp = db_get_value((int) &(*fp)->f_frame, 4, false); 272 273 /* 274 * Figure out frame type. We look at the address just before 275 * the saved instruction pointer as the saved EIP is after the 276 * call function, and if the function being called is marked as 277 * dead (such as panic() at the end of dblfault_handler()), then 278 * the instruction at the saved EIP will be part of a different 279 * function (syscall() in this example) rather than the one that 280 * actually made the call. 281 */ 282 frame_type = NORMAL; 283 284 if (eip >= PMAP_TRM_MIN_ADDRESS) { 285 sym = db_search_symbol(eip - 1 - setidt_disp, DB_STGY_ANY, 286 &offset); 287 } else { 288 sym = db_search_symbol(eip - 1, DB_STGY_ANY, &offset); 289 } 290 db_symbol_values(sym, &name, NULL); 291 if (name != NULL) { 292 if (strcmp(name, "calltrap") == 0 || 293 strcmp(name, "fork_trampoline") == 0) 294 frame_type = TRAP; 295 else if (strncmp(name, "Xatpic_intr", 11) == 0 || 296 strncmp(name, "Xapic_isr", 9) == 0) { 297 frame_type = INTERRUPT; 298 } else if (strcmp(name, "Xlcall_syscall") == 0 || 299 strcmp(name, "Xint0x80_syscall") == 0) 300 frame_type = SYSCALL; 301 else if (strcmp(name, "dblfault_handler") == 0) 302 frame_type = DOUBLE_FAULT; 303 else if (strcmp(name, "Xtimerint") == 0 || 304 strcmp(name, "Xxen_intr_upcall") == 0) 305 frame_type = INTERRUPT; 306 else if (strcmp(name, "Xcpustop") == 0 || 307 strcmp(name, "Xrendezvous") == 0 || 308 strcmp(name, "Xipi_intr_bitmap_handler") == 0) { 309 /* No arguments. */ 310 frame_type = INTERRUPT; 311 } 312 } 313 314 /* 315 * Normal frames need no special processing. 316 */ 317 if (frame_type == NORMAL) { 318 *ip = (db_addr_t) eip; 319 *fp = (struct i386_frame *) ebp; 320 return; 321 } 322 323 db_print_stack_entry(name, 0, 0, 0, eip, &(*fp)->f_frame); 324 325 /* 326 * For a double fault, we have to snag the values from the 327 * previous TSS since a double fault uses a task gate to 328 * switch to a known good state. 329 */ 330 if (frame_type == DOUBLE_FAULT) { 331 esp = PCPU_GET(common_tssp)->tss_esp; 332 eip = PCPU_GET(common_tssp)->tss_eip; 333 ebp = PCPU_GET(common_tssp)->tss_ebp; 334 db_printf( 335 "--- trap 0x17, eip = %#r, esp = %#r, ebp = %#r ---\n", 336 eip, esp, ebp); 337 *ip = (db_addr_t) eip; 338 *fp = (struct i386_frame *) ebp; 339 return; 340 } 341 342 /* 343 * Point to base of trapframe which is just above the current 344 * frame. Pointer to it was put into %ebp by the kernel entry 345 * code. 346 */ 347 tf = (struct trapframe *)(*fp)->f_frame; 348 349 /* 350 * This can be the case for e.g. fork_trampoline, last frame 351 * of a kernel thread stack. 352 */ 353 if (tf == NULL) { 354 *ip = 0; 355 *fp = 0; 356 db_printf("--- kthread start\n"); 357 return; 358 } 359 360 esp = get_esp(tf); 361 eip = tf->tf_eip; 362 ebp = tf->tf_ebp; 363 switch (frame_type) { 364 case TRAP: 365 db_printf("--- trap %#r", tf->tf_trapno); 366 break; 367 case SYSCALL: 368 db_printf("--- syscall"); 369 db_decode_syscall(td, tf->tf_eax); 370 break; 371 case INTERRUPT: 372 db_printf("--- interrupt"); 373 break; 374 default: 375 panic("The moon has moved again."); 376 } 377 db_printf(", eip = %#r, esp = %#r, ebp = %#r ---\n", eip, esp, ebp); 378 379 /* 380 * Detect the last (trap) frame on the kernel stack, where we 381 * entered kernel from usermode. Terminate tracing in this 382 * case. 383 */ 384 switch (frame_type) { 385 case TRAP: 386 case INTERRUPT: 387 if (!TRAPF_USERMODE(tf)) 388 break; 389 /* FALLTHROUGH */ 390 case SYSCALL: 391 ebp = 0; 392 eip = 0; 393 break; 394 } 395 396 *ip = (db_addr_t) eip; 397 *fp = (struct i386_frame *) ebp; 398 } 399 400 static int 401 db_backtrace(struct thread *td, struct trapframe *tf, struct i386_frame *frame, 402 db_addr_t pc, register_t sp, int count) 403 { 404 struct i386_frame *actframe; 405 #define MAXNARG 16 406 char *argnames[MAXNARG], **argnp = NULL; 407 const char *name; 408 int *argp; 409 db_expr_t offset; 410 c_db_sym_t sym; 411 int instr, narg; 412 bool first; 413 414 if (db_segsize(tf) == 16) { 415 db_printf( 416 "--- 16-bit%s, cs:eip = %#x:%#x, ss:esp = %#x:%#x, ebp = %#x, tf = %p ---\n", 417 (tf->tf_eflags & PSL_VM) ? " (vm86)" : "", 418 tf->tf_cs, tf->tf_eip, 419 TF_HAS_STACKREGS(tf) ? tf->tf_ss : rss(), 420 TF_HAS_STACKREGS(tf) ? tf->tf_esp : (intptr_t)&tf->tf_esp, 421 tf->tf_ebp, tf); 422 return (0); 423 } 424 425 /* 'frame' can be null initially. Just print the pc then. */ 426 if (frame == NULL) 427 goto out; 428 429 /* 430 * If an indirect call via an invalid pointer caused a trap, 431 * %pc contains the invalid address while the return address 432 * of the unlucky caller has been saved by CPU on the stack 433 * just before the trap frame. In this case, try to recover 434 * the caller's address so that the first frame is assigned 435 * to the right spot in the right function, for that is where 436 * the failure actually happened. 437 * 438 * This trick depends on the fault address stashed in tf_err 439 * by trap_fatal() before entering KDB. 440 */ 441 if (kdb_frame && pc == kdb_frame->tf_err) { 442 /* 443 * Find where the trap frame actually ends. 444 * It won't contain tf_esp or tf_ss unless crossing rings. 445 */ 446 if (TF_HAS_STACKREGS(kdb_frame)) 447 instr = (int)(kdb_frame + 1); 448 else 449 instr = (int)&kdb_frame->tf_esp; 450 pc = db_get_value(instr, 4, false); 451 } 452 453 if (count == -1) 454 count = 1024; 455 456 first = true; 457 while (count-- && !db_pager_quit) { 458 sym = db_search_symbol(pc, DB_STGY_ANY, &offset); 459 db_symbol_values(sym, &name, NULL); 460 461 /* 462 * Attempt to determine a (possibly fake) frame that gives 463 * the caller's pc. It may differ from `frame' if the 464 * current function never sets up a standard frame or hasn't 465 * set one up yet or has just discarded one. The last two 466 * cases can be guessed fairly reliably for code generated 467 * by gcc. The first case is too much trouble to handle in 468 * general because the amount of junk on the stack depends 469 * on the pc (the special handling of "calltrap", etc. in 470 * db_nextframe() works because the `next' pc is special). 471 */ 472 actframe = frame; 473 if (first) { 474 first = false; 475 if (sym == C_DB_SYM_NULL && sp != 0) { 476 /* 477 * If a symbol couldn't be found, we've probably 478 * jumped to a bogus location, so try and use 479 * the return address to find our caller. 480 */ 481 db_print_stack_entry(name, 0, 0, 0, pc, 482 NULL); 483 pc = db_get_value(sp, 4, false); 484 if (db_search_symbol(pc, DB_STGY_PROC, 485 &offset) == C_DB_SYM_NULL) 486 break; 487 continue; 488 } else if (tf != NULL) { 489 instr = db_get_value(pc, 4, false); 490 if ((instr & 0xffffff) == 0x00e58955) { 491 /* pushl %ebp; movl %esp, %ebp */ 492 actframe = (void *)(get_esp(tf) - 4); 493 } else if ((instr & 0xffff) == 0x0000e589) { 494 /* movl %esp, %ebp */ 495 actframe = (void *)get_esp(tf); 496 if (tf->tf_ebp == 0) { 497 /* Fake frame better. */ 498 frame = actframe; 499 } 500 } else if ((instr & 0xff) == 0x000000c3) { 501 /* ret */ 502 actframe = (void *)(get_esp(tf) - 4); 503 } else if (offset == 0) { 504 /* Probably an assembler symbol. */ 505 actframe = (void *)(get_esp(tf) - 4); 506 } 507 } else if (strcmp(name, "fork_trampoline") == 0) { 508 /* 509 * Don't try to walk back on a stack for a 510 * process that hasn't actually been run yet. 511 */ 512 db_print_stack_entry(name, 0, 0, 0, pc, 513 actframe); 514 break; 515 } 516 } 517 518 argp = &actframe->f_arg0; 519 narg = MAXNARG; 520 if (sym != NULL && db_sym_numargs(sym, &narg, argnames)) { 521 argnp = argnames; 522 } else { 523 narg = db_numargs(frame); 524 } 525 526 db_print_stack_entry(name, narg, argnp, argp, pc, actframe); 527 528 if (actframe != frame) { 529 /* `frame' belongs to caller. */ 530 pc = (db_addr_t) 531 db_get_value((int)&actframe->f_retaddr, 4, false); 532 continue; 533 } 534 535 db_nextframe(&frame, &pc, td); 536 537 out: 538 /* 539 * 'frame' can be null here, either because it was initially 540 * null or because db_nextframe() found no frame. 541 * db_nextframe() may also have found a non-kernel frame. 542 * !INKERNEL() classifies both. Stop tracing if either, 543 * after printing the pc if it is the kernel. 544 */ 545 if (frame == NULL || frame <= actframe) { 546 if (pc != 0) { 547 sym = db_search_symbol(pc, DB_STGY_ANY, 548 &offset); 549 db_symbol_values(sym, &name, NULL); 550 db_print_stack_entry(name, 0, 0, 0, pc, frame); 551 } 552 break; 553 } 554 } 555 556 return (0); 557 } 558 559 void 560 db_trace_self(void) 561 { 562 struct i386_frame *frame; 563 db_addr_t callpc; 564 register_t ebp; 565 566 __asm __volatile("movl %%ebp,%0" : "=r" (ebp)); 567 frame = (struct i386_frame *)ebp; 568 callpc = (db_addr_t)db_get_value((int)&frame->f_retaddr, 4, false); 569 frame = frame->f_frame; 570 db_backtrace(curthread, NULL, frame, callpc, 0, -1); 571 } 572 573 int 574 db_trace_thread(struct thread *thr, int count) 575 { 576 struct pcb *ctx; 577 struct trapframe *tf; 578 579 ctx = kdb_thr_ctx(thr); 580 tf = thr == kdb_thread ? kdb_frame : NULL; 581 return (db_backtrace(thr, tf, (struct i386_frame *)ctx->pcb_ebp, 582 ctx->pcb_eip, ctx->pcb_esp, count)); 583 } 584 585 void 586 db_md_list_watchpoints(void) 587 { 588 589 dbreg_list_watchpoints(); 590 } 591