traps.c 12 KB

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  1. /*
  2. * arch/xtensa/kernel/traps.c
  3. *
  4. * Exception handling.
  5. *
  6. * Derived from code with the following copyrights:
  7. * Copyright (C) 1994 - 1999 by Ralf Baechle
  8. * Modified for R3000 by Paul M. Antoine, 1995, 1996
  9. * Complete output from die() by Ulf Carlsson, 1998
  10. * Copyright (C) 1999 Silicon Graphics, Inc.
  11. *
  12. * Essentially rewritten for the Xtensa architecture port.
  13. *
  14. * Copyright (C) 2001 - 2013 Tensilica Inc.
  15. *
  16. * Joe Taylor <joe@tensilica.com, joetylr@yahoo.com>
  17. * Chris Zankel <chris@zankel.net>
  18. * Marc Gauthier<marc@tensilica.com, marc@alumni.uwaterloo.ca>
  19. * Kevin Chea
  20. *
  21. * This file is subject to the terms and conditions of the GNU General Public
  22. * License. See the file "COPYING" in the main directory of this archive
  23. * for more details.
  24. */
  25. #include <linux/kernel.h>
  26. #include <linux/sched.h>
  27. #include <linux/init.h>
  28. #include <linux/module.h>
  29. #include <linux/stringify.h>
  30. #include <linux/kallsyms.h>
  31. #include <linux/delay.h>
  32. #include <linux/hardirq.h>
  33. #include <asm/stacktrace.h>
  34. #include <asm/ptrace.h>
  35. #include <asm/timex.h>
  36. #include <asm/uaccess.h>
  37. #include <asm/pgtable.h>
  38. #include <asm/processor.h>
  39. #include <asm/traps.h>
  40. #ifdef CONFIG_KGDB
  41. extern int gdb_enter;
  42. extern int return_from_debug_flag;
  43. #endif
  44. /*
  45. * Machine specific interrupt handlers
  46. */
  47. extern void kernel_exception(void);
  48. extern void user_exception(void);
  49. extern void fast_syscall_kernel(void);
  50. extern void fast_syscall_user(void);
  51. extern void fast_alloca(void);
  52. extern void fast_unaligned(void);
  53. extern void fast_second_level_miss(void);
  54. extern void fast_store_prohibited(void);
  55. extern void fast_coprocessor(void);
  56. extern void do_illegal_instruction (struct pt_regs*);
  57. extern void do_interrupt (struct pt_regs*);
  58. extern void do_unaligned_user (struct pt_regs*);
  59. extern void do_multihit (struct pt_regs*, unsigned long);
  60. extern void do_page_fault (struct pt_regs*, unsigned long);
  61. extern void do_debug (struct pt_regs*);
  62. extern void system_call (struct pt_regs*);
  63. /*
  64. * The vector table must be preceded by a save area (which
  65. * implies it must be in RAM, unless one places RAM immediately
  66. * before a ROM and puts the vector at the start of the ROM (!))
  67. */
  68. #define KRNL 0x01
  69. #define USER 0x02
  70. #define COPROCESSOR(x) \
  71. { EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER, fast_coprocessor }
  72. typedef struct {
  73. int cause;
  74. int fast;
  75. void* handler;
  76. } dispatch_init_table_t;
  77. static dispatch_init_table_t __initdata dispatch_init_table[] = {
  78. { EXCCAUSE_ILLEGAL_INSTRUCTION, 0, do_illegal_instruction},
  79. { EXCCAUSE_SYSTEM_CALL, KRNL, fast_syscall_kernel },
  80. { EXCCAUSE_SYSTEM_CALL, USER, fast_syscall_user },
  81. { EXCCAUSE_SYSTEM_CALL, 0, system_call },
  82. /* EXCCAUSE_INSTRUCTION_FETCH unhandled */
  83. /* EXCCAUSE_LOAD_STORE_ERROR unhandled*/
  84. { EXCCAUSE_LEVEL1_INTERRUPT, 0, do_interrupt },
  85. { EXCCAUSE_ALLOCA, USER|KRNL, fast_alloca },
  86. /* EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */
  87. /* EXCCAUSE_PRIVILEGED unhandled */
  88. #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
  89. #ifdef CONFIG_XTENSA_UNALIGNED_USER
  90. { EXCCAUSE_UNALIGNED, USER, fast_unaligned },
  91. #else
  92. { EXCCAUSE_UNALIGNED, 0, do_unaligned_user },
  93. #endif
  94. { EXCCAUSE_UNALIGNED, KRNL, fast_unaligned },
  95. #endif
  96. #ifdef CONFIG_MMU
  97. { EXCCAUSE_ITLB_MISS, 0, do_page_fault },
  98. { EXCCAUSE_ITLB_MISS, USER|KRNL, fast_second_level_miss},
  99. { EXCCAUSE_ITLB_MULTIHIT, 0, do_multihit },
  100. { EXCCAUSE_ITLB_PRIVILEGE, 0, do_page_fault },
  101. /* EXCCAUSE_SIZE_RESTRICTION unhandled */
  102. { EXCCAUSE_FETCH_CACHE_ATTRIBUTE, 0, do_page_fault },
  103. { EXCCAUSE_DTLB_MISS, USER|KRNL, fast_second_level_miss},
  104. { EXCCAUSE_DTLB_MISS, 0, do_page_fault },
  105. { EXCCAUSE_DTLB_MULTIHIT, 0, do_multihit },
  106. { EXCCAUSE_DTLB_PRIVILEGE, 0, do_page_fault },
  107. /* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */
  108. { EXCCAUSE_STORE_CACHE_ATTRIBUTE, USER|KRNL, fast_store_prohibited },
  109. { EXCCAUSE_STORE_CACHE_ATTRIBUTE, 0, do_page_fault },
  110. { EXCCAUSE_LOAD_CACHE_ATTRIBUTE, 0, do_page_fault },
  111. #endif /* CONFIG_MMU */
  112. /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */
  113. #if XTENSA_HAVE_COPROCESSOR(0)
  114. COPROCESSOR(0),
  115. #endif
  116. #if XTENSA_HAVE_COPROCESSOR(1)
  117. COPROCESSOR(1),
  118. #endif
  119. #if XTENSA_HAVE_COPROCESSOR(2)
  120. COPROCESSOR(2),
  121. #endif
  122. #if XTENSA_HAVE_COPROCESSOR(3)
  123. COPROCESSOR(3),
  124. #endif
  125. #if XTENSA_HAVE_COPROCESSOR(4)
  126. COPROCESSOR(4),
  127. #endif
  128. #if XTENSA_HAVE_COPROCESSOR(5)
  129. COPROCESSOR(5),
  130. #endif
  131. #if XTENSA_HAVE_COPROCESSOR(6)
  132. COPROCESSOR(6),
  133. #endif
  134. #if XTENSA_HAVE_COPROCESSOR(7)
  135. COPROCESSOR(7),
  136. #endif
  137. { EXCCAUSE_MAPPED_DEBUG, 0, do_debug },
  138. { -1, -1, 0 }
  139. };
  140. /* The exception table <exc_table> serves two functions:
  141. * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c)
  142. * 2. it is a temporary memory buffer for the exception handlers.
  143. */
  144. unsigned long exc_table[EXC_TABLE_SIZE/4];
  145. void die(const char*, struct pt_regs*, long);
  146. static inline void
  147. __die_if_kernel(const char *str, struct pt_regs *regs, long err)
  148. {
  149. if (!user_mode(regs))
  150. die(str, regs, err);
  151. }
  152. /*
  153. * Unhandled Exceptions. Kill user task or panic if in kernel space.
  154. */
  155. void do_unhandled(struct pt_regs *regs, unsigned long exccause)
  156. {
  157. __die_if_kernel("Caught unhandled exception - should not happen",
  158. regs, SIGKILL);
  159. /* If in user mode, send SIGILL signal to current process */
  160. printk("Caught unhandled exception in '%s' "
  161. "(pid = %d, pc = %#010lx) - should not happen\n"
  162. "\tEXCCAUSE is %ld\n",
  163. current->comm, task_pid_nr(current), regs->pc, exccause);
  164. force_sig(SIGILL, current);
  165. }
  166. /*
  167. * Multi-hit exception. This if fatal!
  168. */
  169. void do_multihit(struct pt_regs *regs, unsigned long exccause)
  170. {
  171. die("Caught multihit exception", regs, SIGKILL);
  172. }
  173. /*
  174. * IRQ handler.
  175. */
  176. extern void do_IRQ(int, struct pt_regs *);
  177. void do_interrupt(struct pt_regs *regs)
  178. {
  179. static const unsigned int_level_mask[] = {
  180. 0,
  181. XCHAL_INTLEVEL1_MASK,
  182. XCHAL_INTLEVEL2_MASK,
  183. XCHAL_INTLEVEL3_MASK,
  184. XCHAL_INTLEVEL4_MASK,
  185. XCHAL_INTLEVEL5_MASK,
  186. XCHAL_INTLEVEL6_MASK,
  187. XCHAL_INTLEVEL7_MASK,
  188. };
  189. for (;;) {
  190. unsigned intread = get_sr(interrupt);
  191. unsigned intenable = get_sr(intenable);
  192. unsigned int_at_level = intread & intenable;
  193. unsigned level;
  194. for (level = LOCKLEVEL; level > 0; --level) {
  195. if (int_at_level & int_level_mask[level]) {
  196. int_at_level &= int_level_mask[level];
  197. break;
  198. }
  199. }
  200. if (level == 0)
  201. return;
  202. /*
  203. * Clear the interrupt before processing, in case it's
  204. * edge-triggered or software-generated
  205. */
  206. while (int_at_level) {
  207. unsigned i = __ffs(int_at_level);
  208. unsigned mask = 1 << i;
  209. int_at_level ^= mask;
  210. set_sr(mask, intclear);
  211. do_IRQ(i, regs);
  212. }
  213. }
  214. }
  215. /*
  216. * Illegal instruction. Fatal if in kernel space.
  217. */
  218. void
  219. do_illegal_instruction(struct pt_regs *regs)
  220. {
  221. __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);
  222. /* If in user mode, send SIGILL signal to current process. */
  223. printk("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n",
  224. current->comm, task_pid_nr(current), regs->pc);
  225. force_sig(SIGILL, current);
  226. }
  227. /*
  228. * Handle unaligned memory accesses from user space. Kill task.
  229. *
  230. * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory
  231. * accesses causes from user space.
  232. */
  233. #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
  234. #ifndef CONFIG_XTENSA_UNALIGNED_USER
  235. void
  236. do_unaligned_user (struct pt_regs *regs)
  237. {
  238. siginfo_t info;
  239. __die_if_kernel("Unhandled unaligned exception in kernel",
  240. regs, SIGKILL);
  241. current->thread.bad_vaddr = regs->excvaddr;
  242. current->thread.error_code = -3;
  243. printk("Unaligned memory access to %08lx in '%s' "
  244. "(pid = %d, pc = %#010lx)\n",
  245. regs->excvaddr, current->comm, task_pid_nr(current), regs->pc);
  246. info.si_signo = SIGBUS;
  247. info.si_errno = 0;
  248. info.si_code = BUS_ADRALN;
  249. info.si_addr = (void *) regs->excvaddr;
  250. force_sig_info(SIGSEGV, &info, current);
  251. }
  252. #endif
  253. #endif
  254. void
  255. do_debug(struct pt_regs *regs)
  256. {
  257. #ifdef CONFIG_KGDB
  258. /* If remote debugging is configured AND enabled, we give control to
  259. * kgdb. Otherwise, we fall through, perhaps giving control to the
  260. * native debugger.
  261. */
  262. if (gdb_enter) {
  263. extern void gdb_handle_exception(struct pt_regs *);
  264. gdb_handle_exception(regs);
  265. return_from_debug_flag = 1;
  266. return;
  267. }
  268. #endif
  269. __die_if_kernel("Breakpoint in kernel", regs, SIGKILL);
  270. /* If in user mode, send SIGTRAP signal to current process */
  271. force_sig(SIGTRAP, current);
  272. }
  273. /* Set exception C handler - for temporary use when probing exceptions */
  274. void * __init trap_set_handler(int cause, void *handler)
  275. {
  276. unsigned long *entry = &exc_table[EXC_TABLE_DEFAULT / 4 + cause];
  277. void *previous = (void *)*entry;
  278. *entry = (unsigned long)handler;
  279. return previous;
  280. }
  281. /*
  282. * Initialize dispatch tables.
  283. *
  284. * The exception vectors are stored compressed the __init section in the
  285. * dispatch_init_table. This function initializes the following three tables
  286. * from that compressed table:
  287. * - fast user first dispatch table for user exceptions
  288. * - fast kernel first dispatch table for kernel exceptions
  289. * - default C-handler C-handler called by the default fast handler.
  290. *
  291. * See vectors.S for more details.
  292. */
  293. #define set_handler(idx,handler) (exc_table[idx] = (unsigned long) (handler))
  294. void __init trap_init(void)
  295. {
  296. int i;
  297. /* Setup default vectors. */
  298. for(i = 0; i < 64; i++) {
  299. set_handler(EXC_TABLE_FAST_USER/4 + i, user_exception);
  300. set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception);
  301. set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled);
  302. }
  303. /* Setup specific handlers. */
  304. for(i = 0; dispatch_init_table[i].cause >= 0; i++) {
  305. int fast = dispatch_init_table[i].fast;
  306. int cause = dispatch_init_table[i].cause;
  307. void *handler = dispatch_init_table[i].handler;
  308. if (fast == 0)
  309. set_handler (EXC_TABLE_DEFAULT/4 + cause, handler);
  310. if (fast && fast & USER)
  311. set_handler (EXC_TABLE_FAST_USER/4 + cause, handler);
  312. if (fast && fast & KRNL)
  313. set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler);
  314. }
  315. /* Initialize EXCSAVE_1 to hold the address of the exception table. */
  316. i = (unsigned long)exc_table;
  317. __asm__ __volatile__("wsr %0, excsave1\n" : : "a" (i));
  318. }
  319. /*
  320. * This function dumps the current valid window frame and other base registers.
  321. */
  322. void show_regs(struct pt_regs * regs)
  323. {
  324. int i, wmask;
  325. show_regs_print_info(KERN_DEFAULT);
  326. wmask = regs->wmask & ~1;
  327. for (i = 0; i < 16; i++) {
  328. if ((i % 8) == 0)
  329. printk(KERN_INFO "a%02d:", i);
  330. printk(KERN_CONT " %08lx", regs->areg[i]);
  331. }
  332. printk(KERN_CONT "\n");
  333. printk("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n",
  334. regs->pc, regs->ps, regs->depc, regs->excvaddr);
  335. printk("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n",
  336. regs->lbeg, regs->lend, regs->lcount, regs->sar);
  337. if (user_mode(regs))
  338. printk("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n",
  339. regs->windowbase, regs->windowstart, regs->wmask,
  340. regs->syscall);
  341. }
  342. static int show_trace_cb(struct stackframe *frame, void *data)
  343. {
  344. if (kernel_text_address(frame->pc)) {
  345. printk(" [<%08lx>] ", frame->pc);
  346. print_symbol("%s\n", frame->pc);
  347. }
  348. return 0;
  349. }
  350. void show_trace(struct task_struct *task, unsigned long *sp)
  351. {
  352. if (!sp)
  353. sp = stack_pointer(task);
  354. printk("Call Trace:");
  355. #ifdef CONFIG_KALLSYMS
  356. printk("\n");
  357. #endif
  358. walk_stackframe(sp, show_trace_cb, NULL);
  359. printk("\n");
  360. }
  361. /*
  362. * This routine abuses get_user()/put_user() to reference pointers
  363. * with at least a bit of error checking ...
  364. */
  365. static int kstack_depth_to_print = 24;
  366. void show_stack(struct task_struct *task, unsigned long *sp)
  367. {
  368. int i = 0;
  369. unsigned long *stack;
  370. if (!sp)
  371. sp = stack_pointer(task);
  372. stack = sp;
  373. printk("\nStack: ");
  374. for (i = 0; i < kstack_depth_to_print; i++) {
  375. if (kstack_end(sp))
  376. break;
  377. if (i && ((i % 8) == 0))
  378. printk("\n ");
  379. printk("%08lx ", *sp++);
  380. }
  381. printk("\n");
  382. show_trace(task, stack);
  383. }
  384. void show_code(unsigned int *pc)
  385. {
  386. long i;
  387. printk("\nCode:");
  388. for(i = -3 ; i < 6 ; i++) {
  389. unsigned long insn;
  390. if (__get_user(insn, pc + i)) {
  391. printk(" (Bad address in pc)\n");
  392. break;
  393. }
  394. printk("%c%08lx%c",(i?' ':'<'),insn,(i?' ':'>'));
  395. }
  396. }
  397. DEFINE_SPINLOCK(die_lock);
  398. void die(const char * str, struct pt_regs * regs, long err)
  399. {
  400. static int die_counter;
  401. int nl = 0;
  402. console_verbose();
  403. spin_lock_irq(&die_lock);
  404. printk("%s: sig: %ld [#%d]\n", str, err, ++die_counter);
  405. #ifdef CONFIG_PREEMPT
  406. printk("PREEMPT ");
  407. nl = 1;
  408. #endif
  409. if (nl)
  410. printk("\n");
  411. show_regs(regs);
  412. if (!user_mode(regs))
  413. show_stack(NULL, (unsigned long*)regs->areg[1]);
  414. add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
  415. spin_unlock_irq(&die_lock);
  416. if (in_interrupt())
  417. panic("Fatal exception in interrupt");
  418. if (panic_on_oops)
  419. panic("Fatal exception");
  420. do_exit(err);
  421. }