1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 */ 4 5 /* 6 * Copyright (C) 2004 Amit S. Kale <amitkale@linsyssoft.com> 7 * Copyright (C) 2000-2001 VERITAS Software Corporation. 8 * Copyright (C) 2002 Andi Kleen, SuSE Labs 9 * Copyright (C) 2004 LinSysSoft Technologies Pvt. Ltd. 10 * Copyright (C) 2007 MontaVista Software, Inc. 11 * Copyright (C) 2007-2008 Jason Wessel, Wind River Systems, Inc. 12 */ 13 /**************************************************************************** 14 * Contributor: Lake Stevens Instrument Division$ 15 * Written by: Glenn Engel $ 16 * Updated by: Amit Kale<akale@veritas.com> 17 * Updated by: Tom Rini <trini@kernel.crashing.org> 18 * Updated by: Jason Wessel <jason.wessel@windriver.com> 19 * Modified for 386 by Jim Kingdon, Cygnus Support. 20 * Origianl kgdb, compatibility with 2.1.xx kernel by 21 * David Grothe <dave@gcom.com> 22 * Integrated into 2.2.5 kernel by Tigran Aivazian <tigran@sco.com> 23 * X86_64 changes from Andi Kleen's patch merged by Jim Houston 24 */ 25 #include <linux/spinlock.h> 26 #include <linux/kdebug.h> 27 #include <linux/string.h> 28 #include <linux/kernel.h> 29 #include <linux/ptrace.h> 30 #include <linux/sched.h> 31 #include <linux/delay.h> 32 #include <linux/kgdb.h> 33 #include <linux/smp.h> 34 #include <linux/nmi.h> 35 #include <linux/hw_breakpoint.h> 36 #include <linux/uaccess.h> 37 #include <linux/memory.h> 38 39 #include <asm/text-patching.h> 40 #include <asm/debugreg.h> 41 #include <asm/apicdef.h> 42 #include <asm/apic.h> 43 #include <asm/nmi.h> 44 #include <asm/switch_to.h> 45 46 struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = 47 { 48 #ifdef CONFIG_X86_32 49 { "ax", 4, offsetof(struct pt_regs, ax) }, 50 { "cx", 4, offsetof(struct pt_regs, cx) }, 51 { "dx", 4, offsetof(struct pt_regs, dx) }, 52 { "bx", 4, offsetof(struct pt_regs, bx) }, 53 { "sp", 4, offsetof(struct pt_regs, sp) }, 54 { "bp", 4, offsetof(struct pt_regs, bp) }, 55 { "si", 4, offsetof(struct pt_regs, si) }, 56 { "di", 4, offsetof(struct pt_regs, di) }, 57 { "ip", 4, offsetof(struct pt_regs, ip) }, 58 { "flags", 4, offsetof(struct pt_regs, flags) }, 59 { "cs", 4, offsetof(struct pt_regs, cs) }, 60 { "ss", 4, offsetof(struct pt_regs, ss) }, 61 { "ds", 4, offsetof(struct pt_regs, ds) }, 62 { "es", 4, offsetof(struct pt_regs, es) }, 63 #else 64 { "ax", 8, offsetof(struct pt_regs, ax) }, 65 { "bx", 8, offsetof(struct pt_regs, bx) }, 66 { "cx", 8, offsetof(struct pt_regs, cx) }, 67 { "dx", 8, offsetof(struct pt_regs, dx) }, 68 { "si", 8, offsetof(struct pt_regs, si) }, 69 { "di", 8, offsetof(struct pt_regs, di) }, 70 { "bp", 8, offsetof(struct pt_regs, bp) }, 71 { "sp", 8, offsetof(struct pt_regs, sp) }, 72 { "r8", 8, offsetof(struct pt_regs, r8) }, 73 { "r9", 8, offsetof(struct pt_regs, r9) }, 74 { "r10", 8, offsetof(struct pt_regs, r10) }, 75 { "r11", 8, offsetof(struct pt_regs, r11) }, 76 { "r12", 8, offsetof(struct pt_regs, r12) }, 77 { "r13", 8, offsetof(struct pt_regs, r13) }, 78 { "r14", 8, offsetof(struct pt_regs, r14) }, 79 { "r15", 8, offsetof(struct pt_regs, r15) }, 80 { "ip", 8, offsetof(struct pt_regs, ip) }, 81 { "flags", 4, offsetof(struct pt_regs, flags) }, 82 { "cs", 4, offsetof(struct pt_regs, cs) }, 83 { "ss", 4, offsetof(struct pt_regs, ss) }, 84 { "ds", 4, -1 }, 85 { "es", 4, -1 }, 86 #endif 87 { "fs", 4, -1 }, 88 { "gs", 4, -1 }, 89 }; 90 91 int dbg_set_reg(int regno, void *mem, struct pt_regs *regs) 92 { 93 if ( 94 #ifdef CONFIG_X86_32 95 regno == GDB_SS || regno == GDB_FS || regno == GDB_GS || 96 #endif 97 regno == GDB_SP || regno == GDB_ORIG_AX) 98 return 0; 99 100 if (dbg_reg_def[regno].offset != -1) 101 memcpy((void *)regs + dbg_reg_def[regno].offset, mem, 102 dbg_reg_def[regno].size); 103 return 0; 104 } 105 106 char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs) 107 { 108 if (regno == GDB_ORIG_AX) { 109 memcpy(mem, ®s->orig_ax, sizeof(regs->orig_ax)); 110 return "orig_ax"; 111 } 112 if (regno >= DBG_MAX_REG_NUM || regno < 0) 113 return NULL; 114 115 if (dbg_reg_def[regno].offset != -1) 116 memcpy(mem, (void *)regs + dbg_reg_def[regno].offset, 117 dbg_reg_def[regno].size); 118 119 #ifdef CONFIG_X86_32 120 switch (regno) { 121 case GDB_GS: 122 case GDB_FS: 123 *(unsigned long *)mem = 0xFFFF; 124 break; 125 } 126 #endif 127 return dbg_reg_def[regno].name; 128 } 129 130 /** 131 * sleeping_thread_to_gdb_regs - Convert ptrace regs to GDB regs 132 * @gdb_regs: A pointer to hold the registers in the order GDB wants. 133 * @p: The &struct task_struct of the desired process. 134 * 135 * Convert the register values of the sleeping process in @p to 136 * the format that GDB expects. 137 * This function is called when kgdb does not have access to the 138 * &struct pt_regs and therefore it should fill the gdb registers 139 * @gdb_regs with what has been saved in &struct thread_struct 140 * thread field during switch_to. 141 */ 142 void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p) 143 { 144 #ifndef CONFIG_X86_32 145 u32 *gdb_regs32 = (u32 *)gdb_regs; 146 #endif 147 gdb_regs[GDB_AX] = 0; 148 gdb_regs[GDB_BX] = 0; 149 gdb_regs[GDB_CX] = 0; 150 gdb_regs[GDB_DX] = 0; 151 gdb_regs[GDB_SI] = 0; 152 gdb_regs[GDB_DI] = 0; 153 gdb_regs[GDB_BP] = ((struct inactive_task_frame *)p->thread.sp)->bp; 154 #ifdef CONFIG_X86_32 155 gdb_regs[GDB_DS] = __KERNEL_DS; 156 gdb_regs[GDB_ES] = __KERNEL_DS; 157 gdb_regs[GDB_PS] = 0; 158 gdb_regs[GDB_CS] = __KERNEL_CS; 159 gdb_regs[GDB_SS] = __KERNEL_DS; 160 gdb_regs[GDB_FS] = 0xFFFF; 161 gdb_regs[GDB_GS] = 0xFFFF; 162 #else 163 gdb_regs32[GDB_PS] = 0; 164 gdb_regs32[GDB_CS] = __KERNEL_CS; 165 gdb_regs32[GDB_SS] = __KERNEL_DS; 166 gdb_regs[GDB_R8] = 0; 167 gdb_regs[GDB_R9] = 0; 168 gdb_regs[GDB_R10] = 0; 169 gdb_regs[GDB_R11] = 0; 170 gdb_regs[GDB_R12] = 0; 171 gdb_regs[GDB_R13] = 0; 172 gdb_regs[GDB_R14] = 0; 173 gdb_regs[GDB_R15] = 0; 174 #endif 175 gdb_regs[GDB_PC] = 0; 176 gdb_regs[GDB_SP] = p->thread.sp; 177 } 178 179 static struct hw_breakpoint { 180 unsigned enabled; 181 unsigned long addr; 182 int len; 183 int type; 184 struct perf_event * __percpu *pev; 185 } breakinfo[HBP_NUM]; 186 187 static unsigned long early_dr7; 188 189 static void kgdb_correct_hw_break(void) 190 { 191 int breakno; 192 193 for (breakno = 0; breakno < HBP_NUM; breakno++) { 194 struct perf_event *bp; 195 struct arch_hw_breakpoint *info; 196 int val; 197 int cpu = raw_smp_processor_id(); 198 if (!breakinfo[breakno].enabled) 199 continue; 200 if (dbg_is_early) { 201 set_debugreg(breakinfo[breakno].addr, breakno); 202 early_dr7 |= encode_dr7(breakno, 203 breakinfo[breakno].len, 204 breakinfo[breakno].type); 205 set_debugreg(early_dr7, 7); 206 continue; 207 } 208 bp = *per_cpu_ptr(breakinfo[breakno].pev, cpu); 209 info = counter_arch_bp(bp); 210 if (bp->attr.disabled != 1) 211 continue; 212 bp->attr.bp_addr = breakinfo[breakno].addr; 213 bp->attr.bp_len = breakinfo[breakno].len; 214 bp->attr.bp_type = breakinfo[breakno].type; 215 info->address = breakinfo[breakno].addr; 216 info->len = breakinfo[breakno].len; 217 info->type = breakinfo[breakno].type; 218 val = arch_install_hw_breakpoint(bp); 219 if (!val) 220 bp->attr.disabled = 0; 221 } 222 if (!dbg_is_early) 223 hw_breakpoint_restore(); 224 } 225 226 static int hw_break_reserve_slot(int breakno) 227 { 228 int cpu; 229 int cnt = 0; 230 struct perf_event **pevent; 231 232 if (dbg_is_early) 233 return 0; 234 235 for_each_online_cpu(cpu) { 236 cnt++; 237 pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu); 238 if (dbg_reserve_bp_slot(*pevent)) 239 goto fail; 240 } 241 242 return 0; 243 244 fail: 245 for_each_online_cpu(cpu) { 246 cnt--; 247 if (!cnt) 248 break; 249 pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu); 250 dbg_release_bp_slot(*pevent); 251 } 252 return -1; 253 } 254 255 static int hw_break_release_slot(int breakno) 256 { 257 struct perf_event **pevent; 258 int cpu; 259 260 if (dbg_is_early) 261 return 0; 262 263 for_each_online_cpu(cpu) { 264 pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu); 265 if (dbg_release_bp_slot(*pevent)) 266 /* 267 * The debugger is responsible for handing the retry on 268 * remove failure. 269 */ 270 return -1; 271 } 272 return 0; 273 } 274 275 static int 276 kgdb_remove_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype) 277 { 278 int i; 279 280 for (i = 0; i < HBP_NUM; i++) 281 if (breakinfo[i].addr == addr && breakinfo[i].enabled) 282 break; 283 if (i == HBP_NUM) 284 return -1; 285 286 if (hw_break_release_slot(i)) { 287 printk(KERN_ERR "Cannot remove hw breakpoint at %lx\n", addr); 288 return -1; 289 } 290 breakinfo[i].enabled = 0; 291 292 return 0; 293 } 294 295 static void kgdb_remove_all_hw_break(void) 296 { 297 int i; 298 int cpu = raw_smp_processor_id(); 299 struct perf_event *bp; 300 301 for (i = 0; i < HBP_NUM; i++) { 302 if (!breakinfo[i].enabled) 303 continue; 304 bp = *per_cpu_ptr(breakinfo[i].pev, cpu); 305 if (!bp->attr.disabled) { 306 arch_uninstall_hw_breakpoint(bp); 307 bp->attr.disabled = 1; 308 continue; 309 } 310 if (dbg_is_early) 311 early_dr7 &= ~encode_dr7(i, breakinfo[i].len, 312 breakinfo[i].type); 313 else if (hw_break_release_slot(i)) 314 printk(KERN_ERR "KGDB: hw bpt remove failed %lx\n", 315 breakinfo[i].addr); 316 breakinfo[i].enabled = 0; 317 } 318 } 319 320 static int 321 kgdb_set_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype) 322 { 323 int i; 324 325 for (i = 0; i < HBP_NUM; i++) 326 if (!breakinfo[i].enabled) 327 break; 328 if (i == HBP_NUM) 329 return -1; 330 331 switch (bptype) { 332 case BP_HARDWARE_BREAKPOINT: 333 len = 1; 334 breakinfo[i].type = X86_BREAKPOINT_EXECUTE; 335 break; 336 case BP_WRITE_WATCHPOINT: 337 breakinfo[i].type = X86_BREAKPOINT_WRITE; 338 break; 339 case BP_ACCESS_WATCHPOINT: 340 breakinfo[i].type = X86_BREAKPOINT_RW; 341 break; 342 default: 343 return -1; 344 } 345 switch (len) { 346 case 1: 347 breakinfo[i].len = X86_BREAKPOINT_LEN_1; 348 break; 349 case 2: 350 breakinfo[i].len = X86_BREAKPOINT_LEN_2; 351 break; 352 case 4: 353 breakinfo[i].len = X86_BREAKPOINT_LEN_4; 354 break; 355 #ifdef CONFIG_X86_64 356 case 8: 357 breakinfo[i].len = X86_BREAKPOINT_LEN_8; 358 break; 359 #endif 360 default: 361 return -1; 362 } 363 breakinfo[i].addr = addr; 364 if (hw_break_reserve_slot(i)) { 365 breakinfo[i].addr = 0; 366 return -1; 367 } 368 breakinfo[i].enabled = 1; 369 370 return 0; 371 } 372 373 /** 374 * kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb. 375 * @regs: Current &struct pt_regs. 376 * 377 * This function will be called if the particular architecture must 378 * disable hardware debugging while it is processing gdb packets or 379 * handling exception. 380 */ 381 static void kgdb_disable_hw_debug(struct pt_regs *regs) 382 { 383 int i; 384 int cpu = raw_smp_processor_id(); 385 struct perf_event *bp; 386 387 /* Disable hardware debugging while we are in kgdb: */ 388 set_debugreg(0UL, 7); 389 for (i = 0; i < HBP_NUM; i++) { 390 if (!breakinfo[i].enabled) 391 continue; 392 if (dbg_is_early) { 393 early_dr7 &= ~encode_dr7(i, breakinfo[i].len, 394 breakinfo[i].type); 395 continue; 396 } 397 bp = *per_cpu_ptr(breakinfo[i].pev, cpu); 398 if (bp->attr.disabled == 1) 399 continue; 400 arch_uninstall_hw_breakpoint(bp); 401 bp->attr.disabled = 1; 402 } 403 } 404 405 #ifdef CONFIG_SMP 406 /** 407 * kgdb_roundup_cpus - Get other CPUs into a holding pattern 408 * 409 * On SMP systems, we need to get the attention of the other CPUs 410 * and get them be in a known state. This should do what is needed 411 * to get the other CPUs to call kgdb_wait(). Note that on some arches, 412 * the NMI approach is not used for rounding up all the CPUs. For example, 413 * in case of MIPS, smp_call_function() is used to roundup CPUs. 414 * 415 * On non-SMP systems, this is not called. 416 */ 417 void kgdb_roundup_cpus(void) 418 { 419 apic_send_IPI_allbutself(NMI_VECTOR); 420 } 421 #endif 422 423 /** 424 * kgdb_arch_handle_exception - Handle architecture specific GDB packets. 425 * @e_vector: The error vector of the exception that happened. 426 * @signo: The signal number of the exception that happened. 427 * @err_code: The error code of the exception that happened. 428 * @remcomInBuffer: The buffer of the packet we have read. 429 * @remcomOutBuffer: The buffer of %BUFMAX bytes to write a packet into. 430 * @linux_regs: The &struct pt_regs of the current process. 431 * 432 * This function MUST handle the 'c' and 's' command packets, 433 * as well packets to set / remove a hardware breakpoint, if used. 434 * If there are additional packets which the hardware needs to handle, 435 * they are handled here. The code should return -1 if it wants to 436 * process more packets, and a %0 or %1 if it wants to exit from the 437 * kgdb callback. 438 */ 439 int kgdb_arch_handle_exception(int e_vector, int signo, int err_code, 440 char *remcomInBuffer, char *remcomOutBuffer, 441 struct pt_regs *linux_regs) 442 { 443 unsigned long addr; 444 char *ptr; 445 446 switch (remcomInBuffer[0]) { 447 case 'c': 448 case 's': 449 /* try to read optional parameter, pc unchanged if no parm */ 450 ptr = &remcomInBuffer[1]; 451 if (kgdb_hex2long(&ptr, &addr)) 452 linux_regs->ip = addr; 453 /* fall through */ 454 case 'D': 455 case 'k': 456 /* clear the trace bit */ 457 linux_regs->flags &= ~X86_EFLAGS_TF; 458 atomic_set(&kgdb_cpu_doing_single_step, -1); 459 460 /* set the trace bit if we're stepping */ 461 if (remcomInBuffer[0] == 's') { 462 linux_regs->flags |= X86_EFLAGS_TF; 463 atomic_set(&kgdb_cpu_doing_single_step, 464 raw_smp_processor_id()); 465 } 466 467 return 0; 468 } 469 470 /* this means that we do not want to exit from the handler: */ 471 return -1; 472 } 473 474 static inline int 475 single_step_cont(struct pt_regs *regs, struct die_args *args) 476 { 477 /* 478 * Single step exception from kernel space to user space so 479 * eat the exception and continue the process: 480 */ 481 printk(KERN_ERR "KGDB: trap/step from kernel to user space, " 482 "resuming...\n"); 483 kgdb_arch_handle_exception(args->trapnr, args->signr, 484 args->err, "c", "", regs); 485 /* 486 * Reset the BS bit in dr6 (pointed by args->err) to 487 * denote completion of processing 488 */ 489 (*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP; 490 491 return NOTIFY_STOP; 492 } 493 494 static DECLARE_BITMAP(was_in_debug_nmi, NR_CPUS); 495 496 static int kgdb_nmi_handler(unsigned int cmd, struct pt_regs *regs) 497 { 498 int cpu; 499 500 switch (cmd) { 501 case NMI_LOCAL: 502 if (atomic_read(&kgdb_active) != -1) { 503 /* KGDB CPU roundup */ 504 cpu = raw_smp_processor_id(); 505 kgdb_nmicallback(cpu, regs); 506 set_bit(cpu, was_in_debug_nmi); 507 touch_nmi_watchdog(); 508 509 return NMI_HANDLED; 510 } 511 break; 512 513 case NMI_UNKNOWN: 514 cpu = raw_smp_processor_id(); 515 516 if (__test_and_clear_bit(cpu, was_in_debug_nmi)) 517 return NMI_HANDLED; 518 519 break; 520 default: 521 /* do nothing */ 522 break; 523 } 524 return NMI_DONE; 525 } 526 527 static int __kgdb_notify(struct die_args *args, unsigned long cmd) 528 { 529 struct pt_regs *regs = args->regs; 530 531 switch (cmd) { 532 case DIE_DEBUG: 533 if (atomic_read(&kgdb_cpu_doing_single_step) != -1) { 534 if (user_mode(regs)) 535 return single_step_cont(regs, args); 536 break; 537 } else if (test_thread_flag(TIF_SINGLESTEP)) 538 /* This means a user thread is single stepping 539 * a system call which should be ignored 540 */ 541 return NOTIFY_DONE; 542 /* fall through */ 543 default: 544 if (user_mode(regs)) 545 return NOTIFY_DONE; 546 } 547 548 if (kgdb_handle_exception(args->trapnr, args->signr, cmd, regs)) 549 return NOTIFY_DONE; 550 551 /* Must touch watchdog before return to normal operation */ 552 touch_nmi_watchdog(); 553 return NOTIFY_STOP; 554 } 555 556 int kgdb_ll_trap(int cmd, const char *str, 557 struct pt_regs *regs, long err, int trap, int sig) 558 { 559 struct die_args args = { 560 .regs = regs, 561 .str = str, 562 .err = err, 563 .trapnr = trap, 564 .signr = sig, 565 566 }; 567 568 if (!kgdb_io_module_registered) 569 return NOTIFY_DONE; 570 571 return __kgdb_notify(&args, cmd); 572 } 573 574 static int 575 kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr) 576 { 577 unsigned long flags; 578 int ret; 579 580 local_irq_save(flags); 581 ret = __kgdb_notify(ptr, cmd); 582 local_irq_restore(flags); 583 584 return ret; 585 } 586 587 static struct notifier_block kgdb_notifier = { 588 .notifier_call = kgdb_notify, 589 }; 590 591 /** 592 * kgdb_arch_init - Perform any architecture specific initialization. 593 * 594 * This function will handle the initialization of any architecture 595 * specific callbacks. 596 */ 597 int kgdb_arch_init(void) 598 { 599 int retval; 600 601 retval = register_die_notifier(&kgdb_notifier); 602 if (retval) 603 goto out; 604 605 retval = register_nmi_handler(NMI_LOCAL, kgdb_nmi_handler, 606 0, "kgdb"); 607 if (retval) 608 goto out1; 609 610 retval = register_nmi_handler(NMI_UNKNOWN, kgdb_nmi_handler, 611 0, "kgdb"); 612 613 if (retval) 614 goto out2; 615 616 return retval; 617 618 out2: 619 unregister_nmi_handler(NMI_LOCAL, "kgdb"); 620 out1: 621 unregister_die_notifier(&kgdb_notifier); 622 out: 623 return retval; 624 } 625 626 static void kgdb_hw_overflow_handler(struct perf_event *event, 627 struct perf_sample_data *data, struct pt_regs *regs) 628 { 629 struct task_struct *tsk = current; 630 int i; 631 632 for (i = 0; i < 4; i++) 633 if (breakinfo[i].enabled) 634 tsk->thread.debugreg6 |= (DR_TRAP0 << i); 635 } 636 637 void kgdb_arch_late(void) 638 { 639 int i, cpu; 640 struct perf_event_attr attr; 641 struct perf_event **pevent; 642 643 /* 644 * Pre-allocate the hw breakpoint structions in the non-atomic 645 * portion of kgdb because this operation requires mutexs to 646 * complete. 647 */ 648 hw_breakpoint_init(&attr); 649 attr.bp_addr = (unsigned long)kgdb_arch_init; 650 attr.bp_len = HW_BREAKPOINT_LEN_1; 651 attr.bp_type = HW_BREAKPOINT_W; 652 attr.disabled = 1; 653 for (i = 0; i < HBP_NUM; i++) { 654 if (breakinfo[i].pev) 655 continue; 656 breakinfo[i].pev = register_wide_hw_breakpoint(&attr, NULL, NULL); 657 if (IS_ERR((void * __force)breakinfo[i].pev)) { 658 printk(KERN_ERR "kgdb: Could not allocate hw" 659 "breakpoints\nDisabling the kernel debugger\n"); 660 breakinfo[i].pev = NULL; 661 kgdb_arch_exit(); 662 return; 663 } 664 for_each_online_cpu(cpu) { 665 pevent = per_cpu_ptr(breakinfo[i].pev, cpu); 666 pevent[0]->hw.sample_period = 1; 667 pevent[0]->overflow_handler = kgdb_hw_overflow_handler; 668 if (pevent[0]->destroy != NULL) { 669 pevent[0]->destroy = NULL; 670 release_bp_slot(*pevent); 671 } 672 } 673 } 674 } 675 676 /** 677 * kgdb_arch_exit - Perform any architecture specific uninitalization. 678 * 679 * This function will handle the uninitalization of any architecture 680 * specific callbacks, for dynamic registration and unregistration. 681 */ 682 void kgdb_arch_exit(void) 683 { 684 int i; 685 for (i = 0; i < 4; i++) { 686 if (breakinfo[i].pev) { 687 unregister_wide_hw_breakpoint(breakinfo[i].pev); 688 breakinfo[i].pev = NULL; 689 } 690 } 691 unregister_nmi_handler(NMI_UNKNOWN, "kgdb"); 692 unregister_nmi_handler(NMI_LOCAL, "kgdb"); 693 unregister_die_notifier(&kgdb_notifier); 694 } 695 696 /** 697 * 698 * kgdb_skipexception - Bail out of KGDB when we've been triggered. 699 * @exception: Exception vector number 700 * @regs: Current &struct pt_regs. 701 * 702 * On some architectures we need to skip a breakpoint exception when 703 * it occurs after a breakpoint has been removed. 704 * 705 * Skip an int3 exception when it occurs after a breakpoint has been 706 * removed. Backtrack eip by 1 since the int3 would have caused it to 707 * increment by 1. 708 */ 709 int kgdb_skipexception(int exception, struct pt_regs *regs) 710 { 711 if (exception == 3 && kgdb_isremovedbreak(regs->ip - 1)) { 712 regs->ip -= 1; 713 return 1; 714 } 715 return 0; 716 } 717 718 unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs) 719 { 720 if (exception == 3) 721 return instruction_pointer(regs) - 1; 722 return instruction_pointer(regs); 723 } 724 725 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip) 726 { 727 regs->ip = ip; 728 } 729 730 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt) 731 { 732 int err; 733 734 bpt->type = BP_BREAKPOINT; 735 err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr, 736 BREAK_INSTR_SIZE); 737 if (err) 738 return err; 739 err = probe_kernel_write((char *)bpt->bpt_addr, 740 arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE); 741 if (!err) 742 return err; 743 /* 744 * It is safe to call text_poke_kgdb() because normal kernel execution 745 * is stopped on all cores, so long as the text_mutex is not locked. 746 */ 747 if (mutex_is_locked(&text_mutex)) 748 return -EBUSY; 749 text_poke_kgdb((void *)bpt->bpt_addr, arch_kgdb_ops.gdb_bpt_instr, 750 BREAK_INSTR_SIZE); 751 bpt->type = BP_POKE_BREAKPOINT; 752 753 return 0; 754 } 755 756 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt) 757 { 758 if (bpt->type != BP_POKE_BREAKPOINT) 759 goto knl_write; 760 /* 761 * It is safe to call text_poke_kgdb() because normal kernel execution 762 * is stopped on all cores, so long as the text_mutex is not locked. 763 */ 764 if (mutex_is_locked(&text_mutex)) 765 goto knl_write; 766 text_poke_kgdb((void *)bpt->bpt_addr, bpt->saved_instr, 767 BREAK_INSTR_SIZE); 768 return 0; 769 770 knl_write: 771 return probe_kernel_write((char *)bpt->bpt_addr, 772 (char *)bpt->saved_instr, BREAK_INSTR_SIZE); 773 } 774 775 const struct kgdb_arch arch_kgdb_ops = { 776 /* Breakpoint instruction: */ 777 .gdb_bpt_instr = { 0xcc }, 778 .flags = KGDB_HW_BREAKPOINT, 779 .set_hw_breakpoint = kgdb_set_hw_break, 780 .remove_hw_breakpoint = kgdb_remove_hw_break, 781 .disable_hw_break = kgdb_disable_hw_debug, 782 .remove_all_hw_break = kgdb_remove_all_hw_break, 783 .correct_hw_break = kgdb_correct_hw_break, 784 }; 785