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