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