kgdb.c 19 KB

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