1 /* 2 * This program is free software; you can redistribute it and/or modify it 3 * under the terms of the GNU General Public License as published by the 4 * Free Software Foundation; either version 2, or (at your option) any 5 * later version. 6 * 7 * This program is distributed in the hope that it will be useful, but 8 * WITHOUT ANY WARRANTY; without even the implied warranty of 9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 10 * General Public License for more details. 11 * 12 */ 13 14 /* 15 * Copyright (C) 2004 Amit S. Kale <amitkale@linsyssoft.com> 16 * Copyright (C) 2000-2001 VERITAS Software Corporation. 17 * Copyright (C) 2002 Andi Kleen, SuSE Labs 18 * Copyright (C) 2004 LinSysSoft Technologies Pvt. Ltd. 19 * Copyright (C) 2007 MontaVista Software, Inc. 20 * Copyright (C) 2007-2008 Jason Wessel, Wind River Systems, Inc. 21 */ 22 /**************************************************************************** 23 * Contributor: Lake Stevens Instrument Division$ 24 * Written by: Glenn Engel $ 25 * Updated by: Amit Kale<akale@veritas.com> 26 * Updated by: Tom Rini <trini@kernel.crashing.org> 27 * Updated by: Jason Wessel <jason.wessel@windriver.com> 28 * Modified for 386 by Jim Kingdon, Cygnus Support. 29 * Origianl kgdb, compatibility with 2.1.xx kernel by 30 * David Grothe <dave@gcom.com> 31 * Integrated into 2.2.5 kernel by Tigran Aivazian <tigran@sco.com> 32 * X86_64 changes from Andi Kleen's patch merged by Jim Houston 33 */ 34 #include <linux/spinlock.h> 35 #include <linux/kdebug.h> 36 #include <linux/string.h> 37 #include <linux/kernel.h> 38 #include <linux/ptrace.h> 39 #include <linux/sched.h> 40 #include <linux/delay.h> 41 #include <linux/kgdb.h> 42 #include <linux/smp.h> 43 #include <linux/nmi.h> 44 #include <linux/hw_breakpoint.h> 45 #include <linux/uaccess.h> 46 #include <linux/memory.h> 47 48 #include <asm/text-patching.h> 49 #include <asm/debugreg.h> 50 #include <asm/apicdef.h> 51 #include <asm/apic.h> 52 #include <asm/nmi.h> 53 #include <asm/switch_to.h> 54 55 struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = 56 { 57 #ifdef CONFIG_X86_32 58 { "ax", 4, offsetof(struct pt_regs, ax) }, 59 { "cx", 4, offsetof(struct pt_regs, cx) }, 60 { "dx", 4, offsetof(struct pt_regs, dx) }, 61 { "bx", 4, offsetof(struct pt_regs, bx) }, 62 { "sp", 4, offsetof(struct pt_regs, sp) }, 63 { "bp", 4, offsetof(struct pt_regs, bp) }, 64 { "si", 4, offsetof(struct pt_regs, si) }, 65 { "di", 4, offsetof(struct pt_regs, di) }, 66 { "ip", 4, offsetof(struct pt_regs, ip) }, 67 { "flags", 4, offsetof(struct pt_regs, flags) }, 68 { "cs", 4, offsetof(struct pt_regs, cs) }, 69 { "ss", 4, offsetof(struct pt_regs, ss) }, 70 { "ds", 4, offsetof(struct pt_regs, ds) }, 71 { "es", 4, offsetof(struct pt_regs, es) }, 72 #else 73 { "ax", 8, offsetof(struct pt_regs, ax) }, 74 { "bx", 8, offsetof(struct pt_regs, bx) }, 75 { "cx", 8, offsetof(struct pt_regs, cx) }, 76 { "dx", 8, offsetof(struct pt_regs, dx) }, 77 { "si", 8, offsetof(struct pt_regs, si) }, 78 { "di", 8, offsetof(struct pt_regs, di) }, 79 { "bp", 8, offsetof(struct pt_regs, bp) }, 80 { "sp", 8, offsetof(struct pt_regs, sp) }, 81 { "r8", 8, offsetof(struct pt_regs, r8) }, 82 { "r9", 8, offsetof(struct pt_regs, r9) }, 83 { "r10", 8, offsetof(struct pt_regs, r10) }, 84 { "r11", 8, offsetof(struct pt_regs, r11) }, 85 { "r12", 8, offsetof(struct pt_regs, r12) }, 86 { "r13", 8, offsetof(struct pt_regs, r13) }, 87 { "r14", 8, offsetof(struct pt_regs, r14) }, 88 { "r15", 8, offsetof(struct pt_regs, r15) }, 89 { "ip", 8, offsetof(struct pt_regs, ip) }, 90 { "flags", 4, offsetof(struct pt_regs, flags) }, 91 { "cs", 4, offsetof(struct pt_regs, cs) }, 92 { "ss", 4, offsetof(struct pt_regs, ss) }, 93 { "ds", 4, -1 }, 94 { "es", 4, -1 }, 95 #endif 96 { "fs", 4, -1 }, 97 { "gs", 4, -1 }, 98 }; 99 100 int dbg_set_reg(int regno, void *mem, struct pt_regs *regs) 101 { 102 if ( 103 #ifdef CONFIG_X86_32 104 regno == GDB_SS || regno == GDB_FS || regno == GDB_GS || 105 #endif 106 regno == GDB_SP || regno == GDB_ORIG_AX) 107 return 0; 108 109 if (dbg_reg_def[regno].offset != -1) 110 memcpy((void *)regs + dbg_reg_def[regno].offset, mem, 111 dbg_reg_def[regno].size); 112 return 0; 113 } 114 115 char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs) 116 { 117 if (regno == GDB_ORIG_AX) { 118 memcpy(mem, ®s->orig_ax, sizeof(regs->orig_ax)); 119 return "orig_ax"; 120 } 121 if (regno >= DBG_MAX_REG_NUM || regno < 0) 122 return NULL; 123 124 if (dbg_reg_def[regno].offset != -1) 125 memcpy(mem, (void *)regs + dbg_reg_def[regno].offset, 126 dbg_reg_def[regno].size); 127 128 #ifdef CONFIG_X86_32 129 switch (regno) { 130 case GDB_SS: 131 if (!user_mode(regs)) 132 *(unsigned long *)mem = __KERNEL_DS; 133 break; 134 case GDB_SP: 135 if (!user_mode(regs)) 136 *(unsigned long *)mem = kernel_stack_pointer(regs); 137 break; 138 case GDB_GS: 139 case GDB_FS: 140 *(unsigned long *)mem = 0xFFFF; 141 break; 142 } 143 #endif 144 return dbg_reg_def[regno].name; 145 } 146 147 /** 148 * sleeping_thread_to_gdb_regs - Convert ptrace regs to GDB regs 149 * @gdb_regs: A pointer to hold the registers in the order GDB wants. 150 * @p: The &struct task_struct of the desired process. 151 * 152 * Convert the register values of the sleeping process in @p to 153 * the format that GDB expects. 154 * This function is called when kgdb does not have access to the 155 * &struct pt_regs and therefore it should fill the gdb registers 156 * @gdb_regs with what has been saved in &struct thread_struct 157 * thread field during switch_to. 158 */ 159 void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p) 160 { 161 #ifndef CONFIG_X86_32 162 u32 *gdb_regs32 = (u32 *)gdb_regs; 163 #endif 164 gdb_regs[GDB_AX] = 0; 165 gdb_regs[GDB_BX] = 0; 166 gdb_regs[GDB_CX] = 0; 167 gdb_regs[GDB_DX] = 0; 168 gdb_regs[GDB_SI] = 0; 169 gdb_regs[GDB_DI] = 0; 170 gdb_regs[GDB_BP] = ((struct inactive_task_frame *)p->thread.sp)->bp; 171 #ifdef CONFIG_X86_32 172 gdb_regs[GDB_DS] = __KERNEL_DS; 173 gdb_regs[GDB_ES] = __KERNEL_DS; 174 gdb_regs[GDB_PS] = 0; 175 gdb_regs[GDB_CS] = __KERNEL_CS; 176 gdb_regs[GDB_SS] = __KERNEL_DS; 177 gdb_regs[GDB_FS] = 0xFFFF; 178 gdb_regs[GDB_GS] = 0xFFFF; 179 #else 180 gdb_regs32[GDB_PS] = 0; 181 gdb_regs32[GDB_CS] = __KERNEL_CS; 182 gdb_regs32[GDB_SS] = __KERNEL_DS; 183 gdb_regs[GDB_R8] = 0; 184 gdb_regs[GDB_R9] = 0; 185 gdb_regs[GDB_R10] = 0; 186 gdb_regs[GDB_R11] = 0; 187 gdb_regs[GDB_R12] = 0; 188 gdb_regs[GDB_R13] = 0; 189 gdb_regs[GDB_R14] = 0; 190 gdb_regs[GDB_R15] = 0; 191 #endif 192 gdb_regs[GDB_PC] = 0; 193 gdb_regs[GDB_SP] = p->thread.sp; 194 } 195 196 static struct hw_breakpoint { 197 unsigned enabled; 198 unsigned long addr; 199 int len; 200 int type; 201 struct perf_event * __percpu *pev; 202 } breakinfo[HBP_NUM]; 203 204 static unsigned long early_dr7; 205 206 static void kgdb_correct_hw_break(void) 207 { 208 int breakno; 209 210 for (breakno = 0; breakno < HBP_NUM; breakno++) { 211 struct perf_event *bp; 212 struct arch_hw_breakpoint *info; 213 int val; 214 int cpu = raw_smp_processor_id(); 215 if (!breakinfo[breakno].enabled) 216 continue; 217 if (dbg_is_early) { 218 set_debugreg(breakinfo[breakno].addr, breakno); 219 early_dr7 |= encode_dr7(breakno, 220 breakinfo[breakno].len, 221 breakinfo[breakno].type); 222 set_debugreg(early_dr7, 7); 223 continue; 224 } 225 bp = *per_cpu_ptr(breakinfo[breakno].pev, cpu); 226 info = counter_arch_bp(bp); 227 if (bp->attr.disabled != 1) 228 continue; 229 bp->attr.bp_addr = breakinfo[breakno].addr; 230 bp->attr.bp_len = breakinfo[breakno].len; 231 bp->attr.bp_type = breakinfo[breakno].type; 232 info->address = breakinfo[breakno].addr; 233 info->len = breakinfo[breakno].len; 234 info->type = breakinfo[breakno].type; 235 val = arch_install_hw_breakpoint(bp); 236 if (!val) 237 bp->attr.disabled = 0; 238 } 239 if (!dbg_is_early) 240 hw_breakpoint_restore(); 241 } 242 243 static int hw_break_reserve_slot(int breakno) 244 { 245 int cpu; 246 int cnt = 0; 247 struct perf_event **pevent; 248 249 if (dbg_is_early) 250 return 0; 251 252 for_each_online_cpu(cpu) { 253 cnt++; 254 pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu); 255 if (dbg_reserve_bp_slot(*pevent)) 256 goto fail; 257 } 258 259 return 0; 260 261 fail: 262 for_each_online_cpu(cpu) { 263 cnt--; 264 if (!cnt) 265 break; 266 pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu); 267 dbg_release_bp_slot(*pevent); 268 } 269 return -1; 270 } 271 272 static int hw_break_release_slot(int breakno) 273 { 274 struct perf_event **pevent; 275 int cpu; 276 277 if (dbg_is_early) 278 return 0; 279 280 for_each_online_cpu(cpu) { 281 pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu); 282 if (dbg_release_bp_slot(*pevent)) 283 /* 284 * The debugger is responsible for handing the retry on 285 * remove failure. 286 */ 287 return -1; 288 } 289 return 0; 290 } 291 292 static int 293 kgdb_remove_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype) 294 { 295 int i; 296 297 for (i = 0; i < HBP_NUM; i++) 298 if (breakinfo[i].addr == addr && breakinfo[i].enabled) 299 break; 300 if (i == HBP_NUM) 301 return -1; 302 303 if (hw_break_release_slot(i)) { 304 printk(KERN_ERR "Cannot remove hw breakpoint at %lx\n", addr); 305 return -1; 306 } 307 breakinfo[i].enabled = 0; 308 309 return 0; 310 } 311 312 static void kgdb_remove_all_hw_break(void) 313 { 314 int i; 315 int cpu = raw_smp_processor_id(); 316 struct perf_event *bp; 317 318 for (i = 0; i < HBP_NUM; i++) { 319 if (!breakinfo[i].enabled) 320 continue; 321 bp = *per_cpu_ptr(breakinfo[i].pev, cpu); 322 if (!bp->attr.disabled) { 323 arch_uninstall_hw_breakpoint(bp); 324 bp->attr.disabled = 1; 325 continue; 326 } 327 if (dbg_is_early) 328 early_dr7 &= ~encode_dr7(i, breakinfo[i].len, 329 breakinfo[i].type); 330 else if (hw_break_release_slot(i)) 331 printk(KERN_ERR "KGDB: hw bpt remove failed %lx\n", 332 breakinfo[i].addr); 333 breakinfo[i].enabled = 0; 334 } 335 } 336 337 static int 338 kgdb_set_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype) 339 { 340 int i; 341 342 for (i = 0; i < HBP_NUM; i++) 343 if (!breakinfo[i].enabled) 344 break; 345 if (i == HBP_NUM) 346 return -1; 347 348 switch (bptype) { 349 case BP_HARDWARE_BREAKPOINT: 350 len = 1; 351 breakinfo[i].type = X86_BREAKPOINT_EXECUTE; 352 break; 353 case BP_WRITE_WATCHPOINT: 354 breakinfo[i].type = X86_BREAKPOINT_WRITE; 355 break; 356 case BP_ACCESS_WATCHPOINT: 357 breakinfo[i].type = X86_BREAKPOINT_RW; 358 break; 359 default: 360 return -1; 361 } 362 switch (len) { 363 case 1: 364 breakinfo[i].len = X86_BREAKPOINT_LEN_1; 365 break; 366 case 2: 367 breakinfo[i].len = X86_BREAKPOINT_LEN_2; 368 break; 369 case 4: 370 breakinfo[i].len = X86_BREAKPOINT_LEN_4; 371 break; 372 #ifdef CONFIG_X86_64 373 case 8: 374 breakinfo[i].len = X86_BREAKPOINT_LEN_8; 375 break; 376 #endif 377 default: 378 return -1; 379 } 380 breakinfo[i].addr = addr; 381 if (hw_break_reserve_slot(i)) { 382 breakinfo[i].addr = 0; 383 return -1; 384 } 385 breakinfo[i].enabled = 1; 386 387 return 0; 388 } 389 390 /** 391 * kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb. 392 * @regs: Current &struct pt_regs. 393 * 394 * This function will be called if the particular architecture must 395 * disable hardware debugging while it is processing gdb packets or 396 * handling exception. 397 */ 398 static void kgdb_disable_hw_debug(struct pt_regs *regs) 399 { 400 int i; 401 int cpu = raw_smp_processor_id(); 402 struct perf_event *bp; 403 404 /* Disable hardware debugging while we are in kgdb: */ 405 set_debugreg(0UL, 7); 406 for (i = 0; i < HBP_NUM; i++) { 407 if (!breakinfo[i].enabled) 408 continue; 409 if (dbg_is_early) { 410 early_dr7 &= ~encode_dr7(i, breakinfo[i].len, 411 breakinfo[i].type); 412 continue; 413 } 414 bp = *per_cpu_ptr(breakinfo[i].pev, cpu); 415 if (bp->attr.disabled == 1) 416 continue; 417 arch_uninstall_hw_breakpoint(bp); 418 bp->attr.disabled = 1; 419 } 420 } 421 422 #ifdef CONFIG_SMP 423 /** 424 * kgdb_roundup_cpus - Get other CPUs into a holding pattern 425 * @flags: Current IRQ state 426 * 427 * On SMP systems, we need to get the attention of the other CPUs 428 * and get them be in a known state. This should do what is needed 429 * to get the other CPUs to call kgdb_wait(). Note that on some arches, 430 * the NMI approach is not used for rounding up all the CPUs. For example, 431 * in case of MIPS, smp_call_function() is used to roundup CPUs. In 432 * this case, we have to make sure that interrupts are enabled before 433 * calling smp_call_function(). The argument to this function is 434 * the flags that will be used when restoring the interrupts. There is 435 * local_irq_save() call before kgdb_roundup_cpus(). 436 * 437 * On non-SMP systems, this is not called. 438 */ 439 void kgdb_roundup_cpus(unsigned long flags) 440 { 441 apic->send_IPI_allbutself(APIC_DM_NMI); 442 } 443 #endif 444 445 /** 446 * kgdb_arch_handle_exception - Handle architecture specific GDB packets. 447 * @e_vector: The error vector of the exception that happened. 448 * @signo: The signal number of the exception that happened. 449 * @err_code: The error code of the exception that happened. 450 * @remcomInBuffer: The buffer of the packet we have read. 451 * @remcomOutBuffer: The buffer of %BUFMAX bytes to write a packet into. 452 * @linux_regs: The &struct pt_regs of the current process. 453 * 454 * This function MUST handle the 'c' and 's' command packets, 455 * as well packets to set / remove a hardware breakpoint, if used. 456 * If there are additional packets which the hardware needs to handle, 457 * they are handled here. The code should return -1 if it wants to 458 * process more packets, and a %0 or %1 if it wants to exit from the 459 * kgdb callback. 460 */ 461 int kgdb_arch_handle_exception(int e_vector, int signo, int err_code, 462 char *remcomInBuffer, char *remcomOutBuffer, 463 struct pt_regs *linux_regs) 464 { 465 unsigned long addr; 466 char *ptr; 467 468 switch (remcomInBuffer[0]) { 469 case 'c': 470 case 's': 471 /* try to read optional parameter, pc unchanged if no parm */ 472 ptr = &remcomInBuffer[1]; 473 if (kgdb_hex2long(&ptr, &addr)) 474 linux_regs->ip = addr; 475 case 'D': 476 case 'k': 477 /* clear the trace bit */ 478 linux_regs->flags &= ~X86_EFLAGS_TF; 479 atomic_set(&kgdb_cpu_doing_single_step, -1); 480 481 /* set the trace bit if we're stepping */ 482 if (remcomInBuffer[0] == 's') { 483 linux_regs->flags |= X86_EFLAGS_TF; 484 atomic_set(&kgdb_cpu_doing_single_step, 485 raw_smp_processor_id()); 486 } 487 488 return 0; 489 } 490 491 /* this means that we do not want to exit from the handler: */ 492 return -1; 493 } 494 495 static inline int 496 single_step_cont(struct pt_regs *regs, struct die_args *args) 497 { 498 /* 499 * Single step exception from kernel space to user space so 500 * eat the exception and continue the process: 501 */ 502 printk(KERN_ERR "KGDB: trap/step from kernel to user space, " 503 "resuming...\n"); 504 kgdb_arch_handle_exception(args->trapnr, args->signr, 505 args->err, "c", "", regs); 506 /* 507 * Reset the BS bit in dr6 (pointed by args->err) to 508 * denote completion of processing 509 */ 510 (*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP; 511 512 return NOTIFY_STOP; 513 } 514 515 static DECLARE_BITMAP(was_in_debug_nmi, NR_CPUS); 516 517 static int kgdb_nmi_handler(unsigned int cmd, struct pt_regs *regs) 518 { 519 int cpu; 520 521 switch (cmd) { 522 case NMI_LOCAL: 523 if (atomic_read(&kgdb_active) != -1) { 524 /* KGDB CPU roundup */ 525 cpu = raw_smp_processor_id(); 526 kgdb_nmicallback(cpu, regs); 527 set_bit(cpu, was_in_debug_nmi); 528 touch_nmi_watchdog(); 529 530 return NMI_HANDLED; 531 } 532 break; 533 534 case NMI_UNKNOWN: 535 cpu = raw_smp_processor_id(); 536 537 if (__test_and_clear_bit(cpu, was_in_debug_nmi)) 538 return NMI_HANDLED; 539 540 break; 541 default: 542 /* do nothing */ 543 break; 544 } 545 return NMI_DONE; 546 } 547 548 static int __kgdb_notify(struct die_args *args, unsigned long cmd) 549 { 550 struct pt_regs *regs = args->regs; 551 552 switch (cmd) { 553 case DIE_DEBUG: 554 if (atomic_read(&kgdb_cpu_doing_single_step) != -1) { 555 if (user_mode(regs)) 556 return single_step_cont(regs, args); 557 break; 558 } else if (test_thread_flag(TIF_SINGLESTEP)) 559 /* This means a user thread is single stepping 560 * a system call which should be ignored 561 */ 562 return NOTIFY_DONE; 563 /* fall through */ 564 default: 565 if (user_mode(regs)) 566 return NOTIFY_DONE; 567 } 568 569 if (kgdb_handle_exception(args->trapnr, args->signr, cmd, regs)) 570 return NOTIFY_DONE; 571 572 /* Must touch watchdog before return to normal operation */ 573 touch_nmi_watchdog(); 574 return NOTIFY_STOP; 575 } 576 577 int kgdb_ll_trap(int cmd, const char *str, 578 struct pt_regs *regs, long err, int trap, int sig) 579 { 580 struct die_args args = { 581 .regs = regs, 582 .str = str, 583 .err = err, 584 .trapnr = trap, 585 .signr = sig, 586 587 }; 588 589 if (!kgdb_io_module_registered) 590 return NOTIFY_DONE; 591 592 return __kgdb_notify(&args, cmd); 593 } 594 595 static int 596 kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr) 597 { 598 unsigned long flags; 599 int ret; 600 601 local_irq_save(flags); 602 ret = __kgdb_notify(ptr, cmd); 603 local_irq_restore(flags); 604 605 return ret; 606 } 607 608 static struct notifier_block kgdb_notifier = { 609 .notifier_call = kgdb_notify, 610 }; 611 612 /** 613 * kgdb_arch_init - Perform any architecture specific initialization. 614 * 615 * This function will handle the initialization of any architecture 616 * specific callbacks. 617 */ 618 int kgdb_arch_init(void) 619 { 620 int retval; 621 622 retval = register_die_notifier(&kgdb_notifier); 623 if (retval) 624 goto out; 625 626 retval = register_nmi_handler(NMI_LOCAL, kgdb_nmi_handler, 627 0, "kgdb"); 628 if (retval) 629 goto out1; 630 631 retval = register_nmi_handler(NMI_UNKNOWN, kgdb_nmi_handler, 632 0, "kgdb"); 633 634 if (retval) 635 goto out2; 636 637 return retval; 638 639 out2: 640 unregister_nmi_handler(NMI_LOCAL, "kgdb"); 641 out1: 642 unregister_die_notifier(&kgdb_notifier); 643 out: 644 return retval; 645 } 646 647 static void kgdb_hw_overflow_handler(struct perf_event *event, 648 struct perf_sample_data *data, struct pt_regs *regs) 649 { 650 struct task_struct *tsk = current; 651 int i; 652 653 for (i = 0; i < 4; i++) 654 if (breakinfo[i].enabled) 655 tsk->thread.debugreg6 |= (DR_TRAP0 << i); 656 } 657 658 void kgdb_arch_late(void) 659 { 660 int i, cpu; 661 struct perf_event_attr attr; 662 struct perf_event **pevent; 663 664 /* 665 * Pre-allocate the hw breakpoint structions in the non-atomic 666 * portion of kgdb because this operation requires mutexs to 667 * complete. 668 */ 669 hw_breakpoint_init(&attr); 670 attr.bp_addr = (unsigned long)kgdb_arch_init; 671 attr.bp_len = HW_BREAKPOINT_LEN_1; 672 attr.bp_type = HW_BREAKPOINT_W; 673 attr.disabled = 1; 674 for (i = 0; i < HBP_NUM; i++) { 675 if (breakinfo[i].pev) 676 continue; 677 breakinfo[i].pev = register_wide_hw_breakpoint(&attr, NULL, NULL); 678 if (IS_ERR((void * __force)breakinfo[i].pev)) { 679 printk(KERN_ERR "kgdb: Could not allocate hw" 680 "breakpoints\nDisabling the kernel debugger\n"); 681 breakinfo[i].pev = NULL; 682 kgdb_arch_exit(); 683 return; 684 } 685 for_each_online_cpu(cpu) { 686 pevent = per_cpu_ptr(breakinfo[i].pev, cpu); 687 pevent[0]->hw.sample_period = 1; 688 pevent[0]->overflow_handler = kgdb_hw_overflow_handler; 689 if (pevent[0]->destroy != NULL) { 690 pevent[0]->destroy = NULL; 691 release_bp_slot(*pevent); 692 } 693 } 694 } 695 } 696 697 /** 698 * kgdb_arch_exit - Perform any architecture specific uninitalization. 699 * 700 * This function will handle the uninitalization of any architecture 701 * specific callbacks, for dynamic registration and unregistration. 702 */ 703 void kgdb_arch_exit(void) 704 { 705 int i; 706 for (i = 0; i < 4; i++) { 707 if (breakinfo[i].pev) { 708 unregister_wide_hw_breakpoint(breakinfo[i].pev); 709 breakinfo[i].pev = NULL; 710 } 711 } 712 unregister_nmi_handler(NMI_UNKNOWN, "kgdb"); 713 unregister_nmi_handler(NMI_LOCAL, "kgdb"); 714 unregister_die_notifier(&kgdb_notifier); 715 } 716 717 /** 718 * 719 * kgdb_skipexception - Bail out of KGDB when we've been triggered. 720 * @exception: Exception vector number 721 * @regs: Current &struct pt_regs. 722 * 723 * On some architectures we need to skip a breakpoint exception when 724 * it occurs after a breakpoint has been removed. 725 * 726 * Skip an int3 exception when it occurs after a breakpoint has been 727 * removed. Backtrack eip by 1 since the int3 would have caused it to 728 * increment by 1. 729 */ 730 int kgdb_skipexception(int exception, struct pt_regs *regs) 731 { 732 if (exception == 3 && kgdb_isremovedbreak(regs->ip - 1)) { 733 regs->ip -= 1; 734 return 1; 735 } 736 return 0; 737 } 738 739 unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs) 740 { 741 if (exception == 3) 742 return instruction_pointer(regs) - 1; 743 return instruction_pointer(regs); 744 } 745 746 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip) 747 { 748 regs->ip = ip; 749 } 750 751 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt) 752 { 753 int err; 754 char opc[BREAK_INSTR_SIZE]; 755 756 bpt->type = BP_BREAKPOINT; 757 err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr, 758 BREAK_INSTR_SIZE); 759 if (err) 760 return err; 761 err = probe_kernel_write((char *)bpt->bpt_addr, 762 arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE); 763 if (!err) 764 return err; 765 /* 766 * It is safe to call text_poke() because normal kernel execution 767 * is stopped on all cores, so long as the text_mutex is not locked. 768 */ 769 if (mutex_is_locked(&text_mutex)) 770 return -EBUSY; 771 text_poke((void *)bpt->bpt_addr, arch_kgdb_ops.gdb_bpt_instr, 772 BREAK_INSTR_SIZE); 773 err = probe_kernel_read(opc, (char *)bpt->bpt_addr, BREAK_INSTR_SIZE); 774 if (err) 775 return err; 776 if (memcmp(opc, arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE)) 777 return -EINVAL; 778 bpt->type = BP_POKE_BREAKPOINT; 779 780 return err; 781 } 782 783 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt) 784 { 785 int err; 786 char opc[BREAK_INSTR_SIZE]; 787 788 if (bpt->type != BP_POKE_BREAKPOINT) 789 goto knl_write; 790 /* 791 * It is safe to call text_poke() because normal kernel execution 792 * is stopped on all cores, so long as the text_mutex is not locked. 793 */ 794 if (mutex_is_locked(&text_mutex)) 795 goto knl_write; 796 text_poke((void *)bpt->bpt_addr, bpt->saved_instr, BREAK_INSTR_SIZE); 797 err = probe_kernel_read(opc, (char *)bpt->bpt_addr, BREAK_INSTR_SIZE); 798 if (err || memcmp(opc, bpt->saved_instr, BREAK_INSTR_SIZE)) 799 goto knl_write; 800 return err; 801 802 knl_write: 803 return probe_kernel_write((char *)bpt->bpt_addr, 804 (char *)bpt->saved_instr, BREAK_INSTR_SIZE); 805 } 806 807 struct kgdb_arch arch_kgdb_ops = { 808 /* Breakpoint instruction: */ 809 .gdb_bpt_instr = { 0xcc }, 810 .flags = KGDB_HW_BREAKPOINT, 811 .set_hw_breakpoint = kgdb_set_hw_break, 812 .remove_hw_breakpoint = kgdb_remove_hw_break, 813 .disable_hw_break = kgdb_disable_hw_debug, 814 .remove_all_hw_break = kgdb_remove_all_hw_break, 815 .correct_hw_break = kgdb_correct_hw_break, 816 }; 817