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_SS: 122 if (!user_mode(regs)) 123 *(unsigned long *)mem = __KERNEL_DS; 124 break; 125 case GDB_SP: 126 if (!user_mode(regs)) 127 *(unsigned long *)mem = kernel_stack_pointer(regs); 128 break; 129 case GDB_GS: 130 case GDB_FS: 131 *(unsigned long *)mem = 0xFFFF; 132 break; 133 } 134 #endif 135 return dbg_reg_def[regno].name; 136 } 137 138 /** 139 * sleeping_thread_to_gdb_regs - Convert ptrace regs to GDB regs 140 * @gdb_regs: A pointer to hold the registers in the order GDB wants. 141 * @p: The &struct task_struct of the desired process. 142 * 143 * Convert the register values of the sleeping process in @p to 144 * the format that GDB expects. 145 * This function is called when kgdb does not have access to the 146 * &struct pt_regs and therefore it should fill the gdb registers 147 * @gdb_regs with what has been saved in &struct thread_struct 148 * thread field during switch_to. 149 */ 150 void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p) 151 { 152 #ifndef CONFIG_X86_32 153 u32 *gdb_regs32 = (u32 *)gdb_regs; 154 #endif 155 gdb_regs[GDB_AX] = 0; 156 gdb_regs[GDB_BX] = 0; 157 gdb_regs[GDB_CX] = 0; 158 gdb_regs[GDB_DX] = 0; 159 gdb_regs[GDB_SI] = 0; 160 gdb_regs[GDB_DI] = 0; 161 gdb_regs[GDB_BP] = ((struct inactive_task_frame *)p->thread.sp)->bp; 162 #ifdef CONFIG_X86_32 163 gdb_regs[GDB_DS] = __KERNEL_DS; 164 gdb_regs[GDB_ES] = __KERNEL_DS; 165 gdb_regs[GDB_PS] = 0; 166 gdb_regs[GDB_CS] = __KERNEL_CS; 167 gdb_regs[GDB_SS] = __KERNEL_DS; 168 gdb_regs[GDB_FS] = 0xFFFF; 169 gdb_regs[GDB_GS] = 0xFFFF; 170 #else 171 gdb_regs32[GDB_PS] = 0; 172 gdb_regs32[GDB_CS] = __KERNEL_CS; 173 gdb_regs32[GDB_SS] = __KERNEL_DS; 174 gdb_regs[GDB_R8] = 0; 175 gdb_regs[GDB_R9] = 0; 176 gdb_regs[GDB_R10] = 0; 177 gdb_regs[GDB_R11] = 0; 178 gdb_regs[GDB_R12] = 0; 179 gdb_regs[GDB_R13] = 0; 180 gdb_regs[GDB_R14] = 0; 181 gdb_regs[GDB_R15] = 0; 182 #endif 183 gdb_regs[GDB_PC] = 0; 184 gdb_regs[GDB_SP] = p->thread.sp; 185 } 186 187 static struct hw_breakpoint { 188 unsigned enabled; 189 unsigned long addr; 190 int len; 191 int type; 192 struct perf_event * __percpu *pev; 193 } breakinfo[HBP_NUM]; 194 195 static unsigned long early_dr7; 196 197 static void kgdb_correct_hw_break(void) 198 { 199 int breakno; 200 201 for (breakno = 0; breakno < HBP_NUM; breakno++) { 202 struct perf_event *bp; 203 struct arch_hw_breakpoint *info; 204 int val; 205 int cpu = raw_smp_processor_id(); 206 if (!breakinfo[breakno].enabled) 207 continue; 208 if (dbg_is_early) { 209 set_debugreg(breakinfo[breakno].addr, breakno); 210 early_dr7 |= encode_dr7(breakno, 211 breakinfo[breakno].len, 212 breakinfo[breakno].type); 213 set_debugreg(early_dr7, 7); 214 continue; 215 } 216 bp = *per_cpu_ptr(breakinfo[breakno].pev, cpu); 217 info = counter_arch_bp(bp); 218 if (bp->attr.disabled != 1) 219 continue; 220 bp->attr.bp_addr = breakinfo[breakno].addr; 221 bp->attr.bp_len = breakinfo[breakno].len; 222 bp->attr.bp_type = breakinfo[breakno].type; 223 info->address = breakinfo[breakno].addr; 224 info->len = breakinfo[breakno].len; 225 info->type = breakinfo[breakno].type; 226 val = arch_install_hw_breakpoint(bp); 227 if (!val) 228 bp->attr.disabled = 0; 229 } 230 if (!dbg_is_early) 231 hw_breakpoint_restore(); 232 } 233 234 static int hw_break_reserve_slot(int breakno) 235 { 236 int cpu; 237 int cnt = 0; 238 struct perf_event **pevent; 239 240 if (dbg_is_early) 241 return 0; 242 243 for_each_online_cpu(cpu) { 244 cnt++; 245 pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu); 246 if (dbg_reserve_bp_slot(*pevent)) 247 goto fail; 248 } 249 250 return 0; 251 252 fail: 253 for_each_online_cpu(cpu) { 254 cnt--; 255 if (!cnt) 256 break; 257 pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu); 258 dbg_release_bp_slot(*pevent); 259 } 260 return -1; 261 } 262 263 static int hw_break_release_slot(int breakno) 264 { 265 struct perf_event **pevent; 266 int cpu; 267 268 if (dbg_is_early) 269 return 0; 270 271 for_each_online_cpu(cpu) { 272 pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu); 273 if (dbg_release_bp_slot(*pevent)) 274 /* 275 * The debugger is responsible for handing the retry on 276 * remove failure. 277 */ 278 return -1; 279 } 280 return 0; 281 } 282 283 static int 284 kgdb_remove_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype) 285 { 286 int i; 287 288 for (i = 0; i < HBP_NUM; i++) 289 if (breakinfo[i].addr == addr && breakinfo[i].enabled) 290 break; 291 if (i == HBP_NUM) 292 return -1; 293 294 if (hw_break_release_slot(i)) { 295 printk(KERN_ERR "Cannot remove hw breakpoint at %lx\n", addr); 296 return -1; 297 } 298 breakinfo[i].enabled = 0; 299 300 return 0; 301 } 302 303 static void kgdb_remove_all_hw_break(void) 304 { 305 int i; 306 int cpu = raw_smp_processor_id(); 307 struct perf_event *bp; 308 309 for (i = 0; i < HBP_NUM; i++) { 310 if (!breakinfo[i].enabled) 311 continue; 312 bp = *per_cpu_ptr(breakinfo[i].pev, cpu); 313 if (!bp->attr.disabled) { 314 arch_uninstall_hw_breakpoint(bp); 315 bp->attr.disabled = 1; 316 continue; 317 } 318 if (dbg_is_early) 319 early_dr7 &= ~encode_dr7(i, breakinfo[i].len, 320 breakinfo[i].type); 321 else if (hw_break_release_slot(i)) 322 printk(KERN_ERR "KGDB: hw bpt remove failed %lx\n", 323 breakinfo[i].addr); 324 breakinfo[i].enabled = 0; 325 } 326 } 327 328 static int 329 kgdb_set_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype) 330 { 331 int i; 332 333 for (i = 0; i < HBP_NUM; i++) 334 if (!breakinfo[i].enabled) 335 break; 336 if (i == HBP_NUM) 337 return -1; 338 339 switch (bptype) { 340 case BP_HARDWARE_BREAKPOINT: 341 len = 1; 342 breakinfo[i].type = X86_BREAKPOINT_EXECUTE; 343 break; 344 case BP_WRITE_WATCHPOINT: 345 breakinfo[i].type = X86_BREAKPOINT_WRITE; 346 break; 347 case BP_ACCESS_WATCHPOINT: 348 breakinfo[i].type = X86_BREAKPOINT_RW; 349 break; 350 default: 351 return -1; 352 } 353 switch (len) { 354 case 1: 355 breakinfo[i].len = X86_BREAKPOINT_LEN_1; 356 break; 357 case 2: 358 breakinfo[i].len = X86_BREAKPOINT_LEN_2; 359 break; 360 case 4: 361 breakinfo[i].len = X86_BREAKPOINT_LEN_4; 362 break; 363 #ifdef CONFIG_X86_64 364 case 8: 365 breakinfo[i].len = X86_BREAKPOINT_LEN_8; 366 break; 367 #endif 368 default: 369 return -1; 370 } 371 breakinfo[i].addr = addr; 372 if (hw_break_reserve_slot(i)) { 373 breakinfo[i].addr = 0; 374 return -1; 375 } 376 breakinfo[i].enabled = 1; 377 378 return 0; 379 } 380 381 /** 382 * kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb. 383 * @regs: Current &struct pt_regs. 384 * 385 * This function will be called if the particular architecture must 386 * disable hardware debugging while it is processing gdb packets or 387 * handling exception. 388 */ 389 static void kgdb_disable_hw_debug(struct pt_regs *regs) 390 { 391 int i; 392 int cpu = raw_smp_processor_id(); 393 struct perf_event *bp; 394 395 /* Disable hardware debugging while we are in kgdb: */ 396 set_debugreg(0UL, 7); 397 for (i = 0; i < HBP_NUM; i++) { 398 if (!breakinfo[i].enabled) 399 continue; 400 if (dbg_is_early) { 401 early_dr7 &= ~encode_dr7(i, breakinfo[i].len, 402 breakinfo[i].type); 403 continue; 404 } 405 bp = *per_cpu_ptr(breakinfo[i].pev, cpu); 406 if (bp->attr.disabled == 1) 407 continue; 408 arch_uninstall_hw_breakpoint(bp); 409 bp->attr.disabled = 1; 410 } 411 } 412 413 #ifdef CONFIG_SMP 414 /** 415 * kgdb_roundup_cpus - Get other CPUs into a holding pattern 416 * 417 * On SMP systems, we need to get the attention of the other CPUs 418 * and get them be in a known state. This should do what is needed 419 * to get the other CPUs to call kgdb_wait(). Note that on some arches, 420 * the NMI approach is not used for rounding up all the CPUs. For example, 421 * in case of MIPS, smp_call_function() is used to roundup CPUs. 422 * 423 * On non-SMP systems, this is not called. 424 */ 425 void kgdb_roundup_cpus(void) 426 { 427 apic->send_IPI_allbutself(APIC_DM_NMI); 428 } 429 #endif 430 431 /** 432 * kgdb_arch_handle_exception - Handle architecture specific GDB packets. 433 * @e_vector: The error vector of the exception that happened. 434 * @signo: The signal number of the exception that happened. 435 * @err_code: The error code of the exception that happened. 436 * @remcomInBuffer: The buffer of the packet we have read. 437 * @remcomOutBuffer: The buffer of %BUFMAX bytes to write a packet into. 438 * @linux_regs: The &struct pt_regs of the current process. 439 * 440 * This function MUST handle the 'c' and 's' command packets, 441 * as well packets to set / remove a hardware breakpoint, if used. 442 * If there are additional packets which the hardware needs to handle, 443 * they are handled here. The code should return -1 if it wants to 444 * process more packets, and a %0 or %1 if it wants to exit from the 445 * kgdb callback. 446 */ 447 int kgdb_arch_handle_exception(int e_vector, int signo, int err_code, 448 char *remcomInBuffer, char *remcomOutBuffer, 449 struct pt_regs *linux_regs) 450 { 451 unsigned long addr; 452 char *ptr; 453 454 switch (remcomInBuffer[0]) { 455 case 'c': 456 case 's': 457 /* try to read optional parameter, pc unchanged if no parm */ 458 ptr = &remcomInBuffer[1]; 459 if (kgdb_hex2long(&ptr, &addr)) 460 linux_regs->ip = addr; 461 /* fall through */ 462 case 'D': 463 case 'k': 464 /* clear the trace bit */ 465 linux_regs->flags &= ~X86_EFLAGS_TF; 466 atomic_set(&kgdb_cpu_doing_single_step, -1); 467 468 /* set the trace bit if we're stepping */ 469 if (remcomInBuffer[0] == 's') { 470 linux_regs->flags |= X86_EFLAGS_TF; 471 atomic_set(&kgdb_cpu_doing_single_step, 472 raw_smp_processor_id()); 473 } 474 475 return 0; 476 } 477 478 /* this means that we do not want to exit from the handler: */ 479 return -1; 480 } 481 482 static inline int 483 single_step_cont(struct pt_regs *regs, struct die_args *args) 484 { 485 /* 486 * Single step exception from kernel space to user space so 487 * eat the exception and continue the process: 488 */ 489 printk(KERN_ERR "KGDB: trap/step from kernel to user space, " 490 "resuming...\n"); 491 kgdb_arch_handle_exception(args->trapnr, args->signr, 492 args->err, "c", "", regs); 493 /* 494 * Reset the BS bit in dr6 (pointed by args->err) to 495 * denote completion of processing 496 */ 497 (*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP; 498 499 return NOTIFY_STOP; 500 } 501 502 static DECLARE_BITMAP(was_in_debug_nmi, NR_CPUS); 503 504 static int kgdb_nmi_handler(unsigned int cmd, struct pt_regs *regs) 505 { 506 int cpu; 507 508 switch (cmd) { 509 case NMI_LOCAL: 510 if (atomic_read(&kgdb_active) != -1) { 511 /* KGDB CPU roundup */ 512 cpu = raw_smp_processor_id(); 513 kgdb_nmicallback(cpu, regs); 514 set_bit(cpu, was_in_debug_nmi); 515 touch_nmi_watchdog(); 516 517 return NMI_HANDLED; 518 } 519 break; 520 521 case NMI_UNKNOWN: 522 cpu = raw_smp_processor_id(); 523 524 if (__test_and_clear_bit(cpu, was_in_debug_nmi)) 525 return NMI_HANDLED; 526 527 break; 528 default: 529 /* do nothing */ 530 break; 531 } 532 return NMI_DONE; 533 } 534 535 static int __kgdb_notify(struct die_args *args, unsigned long cmd) 536 { 537 struct pt_regs *regs = args->regs; 538 539 switch (cmd) { 540 case DIE_DEBUG: 541 if (atomic_read(&kgdb_cpu_doing_single_step) != -1) { 542 if (user_mode(regs)) 543 return single_step_cont(regs, args); 544 break; 545 } else if (test_thread_flag(TIF_SINGLESTEP)) 546 /* This means a user thread is single stepping 547 * a system call which should be ignored 548 */ 549 return NOTIFY_DONE; 550 /* fall through */ 551 default: 552 if (user_mode(regs)) 553 return NOTIFY_DONE; 554 } 555 556 if (kgdb_handle_exception(args->trapnr, args->signr, cmd, regs)) 557 return NOTIFY_DONE; 558 559 /* Must touch watchdog before return to normal operation */ 560 touch_nmi_watchdog(); 561 return NOTIFY_STOP; 562 } 563 564 int kgdb_ll_trap(int cmd, const char *str, 565 struct pt_regs *regs, long err, int trap, int sig) 566 { 567 struct die_args args = { 568 .regs = regs, 569 .str = str, 570 .err = err, 571 .trapnr = trap, 572 .signr = sig, 573 574 }; 575 576 if (!kgdb_io_module_registered) 577 return NOTIFY_DONE; 578 579 return __kgdb_notify(&args, cmd); 580 } 581 582 static int 583 kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr) 584 { 585 unsigned long flags; 586 int ret; 587 588 local_irq_save(flags); 589 ret = __kgdb_notify(ptr, cmd); 590 local_irq_restore(flags); 591 592 return ret; 593 } 594 595 static struct notifier_block kgdb_notifier = { 596 .notifier_call = kgdb_notify, 597 }; 598 599 /** 600 * kgdb_arch_init - Perform any architecture specific initialization. 601 * 602 * This function will handle the initialization of any architecture 603 * specific callbacks. 604 */ 605 int kgdb_arch_init(void) 606 { 607 int retval; 608 609 retval = register_die_notifier(&kgdb_notifier); 610 if (retval) 611 goto out; 612 613 retval = register_nmi_handler(NMI_LOCAL, kgdb_nmi_handler, 614 0, "kgdb"); 615 if (retval) 616 goto out1; 617 618 retval = register_nmi_handler(NMI_UNKNOWN, kgdb_nmi_handler, 619 0, "kgdb"); 620 621 if (retval) 622 goto out2; 623 624 return retval; 625 626 out2: 627 unregister_nmi_handler(NMI_LOCAL, "kgdb"); 628 out1: 629 unregister_die_notifier(&kgdb_notifier); 630 out: 631 return retval; 632 } 633 634 static void kgdb_hw_overflow_handler(struct perf_event *event, 635 struct perf_sample_data *data, struct pt_regs *regs) 636 { 637 struct task_struct *tsk = current; 638 int i; 639 640 for (i = 0; i < 4; i++) 641 if (breakinfo[i].enabled) 642 tsk->thread.debugreg6 |= (DR_TRAP0 << i); 643 } 644 645 void kgdb_arch_late(void) 646 { 647 int i, cpu; 648 struct perf_event_attr attr; 649 struct perf_event **pevent; 650 651 /* 652 * Pre-allocate the hw breakpoint structions in the non-atomic 653 * portion of kgdb because this operation requires mutexs to 654 * complete. 655 */ 656 hw_breakpoint_init(&attr); 657 attr.bp_addr = (unsigned long)kgdb_arch_init; 658 attr.bp_len = HW_BREAKPOINT_LEN_1; 659 attr.bp_type = HW_BREAKPOINT_W; 660 attr.disabled = 1; 661 for (i = 0; i < HBP_NUM; i++) { 662 if (breakinfo[i].pev) 663 continue; 664 breakinfo[i].pev = register_wide_hw_breakpoint(&attr, NULL, NULL); 665 if (IS_ERR((void * __force)breakinfo[i].pev)) { 666 printk(KERN_ERR "kgdb: Could not allocate hw" 667 "breakpoints\nDisabling the kernel debugger\n"); 668 breakinfo[i].pev = NULL; 669 kgdb_arch_exit(); 670 return; 671 } 672 for_each_online_cpu(cpu) { 673 pevent = per_cpu_ptr(breakinfo[i].pev, cpu); 674 pevent[0]->hw.sample_period = 1; 675 pevent[0]->overflow_handler = kgdb_hw_overflow_handler; 676 if (pevent[0]->destroy != NULL) { 677 pevent[0]->destroy = NULL; 678 release_bp_slot(*pevent); 679 } 680 } 681 } 682 } 683 684 /** 685 * kgdb_arch_exit - Perform any architecture specific uninitalization. 686 * 687 * This function will handle the uninitalization of any architecture 688 * specific callbacks, for dynamic registration and unregistration. 689 */ 690 void kgdb_arch_exit(void) 691 { 692 int i; 693 for (i = 0; i < 4; i++) { 694 if (breakinfo[i].pev) { 695 unregister_wide_hw_breakpoint(breakinfo[i].pev); 696 breakinfo[i].pev = NULL; 697 } 698 } 699 unregister_nmi_handler(NMI_UNKNOWN, "kgdb"); 700 unregister_nmi_handler(NMI_LOCAL, "kgdb"); 701 unregister_die_notifier(&kgdb_notifier); 702 } 703 704 /** 705 * 706 * kgdb_skipexception - Bail out of KGDB when we've been triggered. 707 * @exception: Exception vector number 708 * @regs: Current &struct pt_regs. 709 * 710 * On some architectures we need to skip a breakpoint exception when 711 * it occurs after a breakpoint has been removed. 712 * 713 * Skip an int3 exception when it occurs after a breakpoint has been 714 * removed. Backtrack eip by 1 since the int3 would have caused it to 715 * increment by 1. 716 */ 717 int kgdb_skipexception(int exception, struct pt_regs *regs) 718 { 719 if (exception == 3 && kgdb_isremovedbreak(regs->ip - 1)) { 720 regs->ip -= 1; 721 return 1; 722 } 723 return 0; 724 } 725 726 unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs) 727 { 728 if (exception == 3) 729 return instruction_pointer(regs) - 1; 730 return instruction_pointer(regs); 731 } 732 733 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip) 734 { 735 regs->ip = ip; 736 } 737 738 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt) 739 { 740 int err; 741 742 bpt->type = BP_BREAKPOINT; 743 err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr, 744 BREAK_INSTR_SIZE); 745 if (err) 746 return err; 747 err = probe_kernel_write((char *)bpt->bpt_addr, 748 arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE); 749 if (!err) 750 return err; 751 /* 752 * It is safe to call text_poke_kgdb() because normal kernel execution 753 * is stopped on all cores, so long as the text_mutex is not locked. 754 */ 755 if (mutex_is_locked(&text_mutex)) 756 return -EBUSY; 757 text_poke_kgdb((void *)bpt->bpt_addr, arch_kgdb_ops.gdb_bpt_instr, 758 BREAK_INSTR_SIZE); 759 bpt->type = BP_POKE_BREAKPOINT; 760 761 return err; 762 } 763 764 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt) 765 { 766 if (bpt->type != BP_POKE_BREAKPOINT) 767 goto knl_write; 768 /* 769 * It is safe to call text_poke_kgdb() because normal kernel execution 770 * is stopped on all cores, so long as the text_mutex is not locked. 771 */ 772 if (mutex_is_locked(&text_mutex)) 773 goto knl_write; 774 text_poke_kgdb((void *)bpt->bpt_addr, bpt->saved_instr, 775 BREAK_INSTR_SIZE); 776 return 0; 777 778 knl_write: 779 return probe_kernel_write((char *)bpt->bpt_addr, 780 (char *)bpt->saved_instr, BREAK_INSTR_SIZE); 781 } 782 783 const struct kgdb_arch arch_kgdb_ops = { 784 /* Breakpoint instruction: */ 785 .gdb_bpt_instr = { 0xcc }, 786 .flags = KGDB_HW_BREAKPOINT, 787 .set_hw_breakpoint = kgdb_set_hw_break, 788 .remove_hw_breakpoint = kgdb_remove_hw_break, 789 .disable_hw_break = kgdb_disable_hw_debug, 790 .remove_all_hw_break = kgdb_remove_all_hw_break, 791 .correct_hw_break = kgdb_correct_hw_break, 792 }; 793