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
26 #include <linux/cpu.h>
27 #include <linux/kernel.h>
28 #include <linux/sched/signal.h>
29 #include <linux/sched/debug.h>
30 #include <linux/sched/task_stack.h>
31 #include <linux/init.h>
32 #include <linux/module.h>
33 #include <linux/stringify.h>
34 #include <linux/kallsyms.h>
35 #include <linux/delay.h>
36 #include <linux/hardirq.h>
37 #include <linux/ratelimit.h>
38 #include <linux/pgtable.h>
39
40 #include <asm/stacktrace.h>
41 #include <asm/ptrace.h>
42 #include <asm/timex.h>
43 #include <linux/uaccess.h>
44 #include <asm/processor.h>
45 #include <asm/traps.h>
46 #include <asm/hw_breakpoint.h>
47
48 /*
49 * Machine specific interrupt handlers
50 */
51
52 static void do_illegal_instruction(struct pt_regs *regs);
53 static void do_div0(struct pt_regs *regs);
54 static void do_interrupt(struct pt_regs *regs);
55 #if XTENSA_FAKE_NMI
56 static void do_nmi(struct pt_regs *regs);
57 #endif
58 #ifdef CONFIG_XTENSA_LOAD_STORE
59 static void do_load_store(struct pt_regs *regs);
60 #endif
61 static void do_unaligned_user(struct pt_regs *regs);
62 static void do_multihit(struct pt_regs *regs);
63 #if XTENSA_HAVE_COPROCESSORS
64 static void do_coprocessor(struct pt_regs *regs);
65 #endif
66 static void do_debug(struct pt_regs *regs);
67
68 /*
69 * The vector table must be preceded by a save area (which
70 * implies it must be in RAM, unless one places RAM immediately
71 * before a ROM and puts the vector at the start of the ROM (!))
72 */
73
74 #define KRNL 0x01
75 #define USER 0x02
76
77 #define COPROCESSOR(x) \
78 { EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER|KRNL, fast_coprocessor },\
79 { EXCCAUSE_COPROCESSOR ## x ## _DISABLED, 0, do_coprocessor }
80
81 typedef struct {
82 int cause;
83 int fast;
84 void* handler;
85 } dispatch_init_table_t;
86
87 static dispatch_init_table_t __initdata dispatch_init_table[] = {
88
89 #ifdef CONFIG_USER_ABI_CALL0_PROBE
90 { EXCCAUSE_ILLEGAL_INSTRUCTION, USER, fast_illegal_instruction_user },
91 #endif
92 { EXCCAUSE_ILLEGAL_INSTRUCTION, 0, do_illegal_instruction},
93 { EXCCAUSE_SYSTEM_CALL, USER, fast_syscall_user },
94 { EXCCAUSE_SYSTEM_CALL, 0, system_call },
95 /* EXCCAUSE_INSTRUCTION_FETCH unhandled */
96 #ifdef CONFIG_XTENSA_LOAD_STORE
97 { EXCCAUSE_LOAD_STORE_ERROR, USER|KRNL, fast_load_store },
98 { EXCCAUSE_LOAD_STORE_ERROR, 0, do_load_store },
99 #endif
100 { EXCCAUSE_LEVEL1_INTERRUPT, 0, do_interrupt },
101 #ifdef SUPPORT_WINDOWED
102 { EXCCAUSE_ALLOCA, USER|KRNL, fast_alloca },
103 #endif
104 { EXCCAUSE_INTEGER_DIVIDE_BY_ZERO, 0, do_div0 },
105 /* EXCCAUSE_PRIVILEGED unhandled */
106 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION || \
107 IS_ENABLED(CONFIG_XTENSA_LOAD_STORE)
108 #ifdef CONFIG_XTENSA_UNALIGNED_USER
109 { EXCCAUSE_UNALIGNED, USER, fast_unaligned },
110 #endif
111 { EXCCAUSE_UNALIGNED, KRNL, fast_unaligned },
112 #endif
113 { EXCCAUSE_UNALIGNED, 0, do_unaligned_user },
114 #ifdef CONFIG_MMU
115 { EXCCAUSE_ITLB_MISS, 0, do_page_fault },
116 { EXCCAUSE_ITLB_MISS, USER|KRNL, fast_second_level_miss},
117 { EXCCAUSE_DTLB_MISS, USER|KRNL, fast_second_level_miss},
118 { EXCCAUSE_DTLB_MISS, 0, do_page_fault },
119 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, USER|KRNL, fast_store_prohibited },
120 #endif /* CONFIG_MMU */
121 #ifdef CONFIG_PFAULT
122 { EXCCAUSE_ITLB_MULTIHIT, 0, do_multihit },
123 { EXCCAUSE_ITLB_PRIVILEGE, 0, do_page_fault },
124 { EXCCAUSE_FETCH_CACHE_ATTRIBUTE, 0, do_page_fault },
125 { EXCCAUSE_DTLB_MULTIHIT, 0, do_multihit },
126 { EXCCAUSE_DTLB_PRIVILEGE, 0, do_page_fault },
127 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, 0, do_page_fault },
128 { EXCCAUSE_LOAD_CACHE_ATTRIBUTE, 0, do_page_fault },
129 #endif
130 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */
131 #if XTENSA_HAVE_COPROCESSOR(0)
132 COPROCESSOR(0),
133 #endif
134 #if XTENSA_HAVE_COPROCESSOR(1)
135 COPROCESSOR(1),
136 #endif
137 #if XTENSA_HAVE_COPROCESSOR(2)
138 COPROCESSOR(2),
139 #endif
140 #if XTENSA_HAVE_COPROCESSOR(3)
141 COPROCESSOR(3),
142 #endif
143 #if XTENSA_HAVE_COPROCESSOR(4)
144 COPROCESSOR(4),
145 #endif
146 #if XTENSA_HAVE_COPROCESSOR(5)
147 COPROCESSOR(5),
148 #endif
149 #if XTENSA_HAVE_COPROCESSOR(6)
150 COPROCESSOR(6),
151 #endif
152 #if XTENSA_HAVE_COPROCESSOR(7)
153 COPROCESSOR(7),
154 #endif
155 #if XTENSA_FAKE_NMI
156 { EXCCAUSE_MAPPED_NMI, 0, do_nmi },
157 #endif
158 { EXCCAUSE_MAPPED_DEBUG, 0, do_debug },
159 { -1, -1, 0 }
160
161 };
162
163 /* The exception table <exc_table> serves two functions:
164 * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c)
165 * 2. it is a temporary memory buffer for the exception handlers.
166 */
167
168 DEFINE_PER_CPU(struct exc_table, exc_table);
169 DEFINE_PER_CPU(struct debug_table, debug_table);
170
171 void die(const char*, struct pt_regs*, long);
172
173 static inline void
174 __die_if_kernel(const char *str, struct pt_regs *regs, long err)
175 {
176 if (!user_mode(regs))
177 die(str, regs, err);
178 }
179
180 #ifdef CONFIG_PRINT_USER_CODE_ON_UNHANDLED_EXCEPTION
181 static inline void dump_user_code(struct pt_regs *regs)
182 {
183 char buf[32];
184
185 if (copy_from_user(buf, (void __user *)(regs->pc & -16), sizeof(buf)) == 0) {
186 print_hex_dump(KERN_INFO, " ", DUMP_PREFIX_NONE,
187 32, 1, buf, sizeof(buf), false);
188
189 }
190 }
191 #else
192 static inline void dump_user_code(struct pt_regs *regs)
193 {
194 }
195 #endif
196
197 /*
198 * Unhandled Exceptions. Kill user task or panic if in kernel space.
199 */
200
201 void do_unhandled(struct pt_regs *regs)
202 {
203 __die_if_kernel("Caught unhandled exception - should not happen",
204 regs, SIGKILL);
205
206 /* If in user mode, send SIGILL signal to current process */
207 pr_info_ratelimited("Caught unhandled exception in '%s' "
208 "(pid = %d, pc = %#010lx) - should not happen\n"
209 "\tEXCCAUSE is %ld\n",
210 current->comm, task_pid_nr(current), regs->pc,
211 regs->exccause);
212 dump_user_code(regs);
213 force_sig(SIGILL);
214 }
215
216 /*
217 * Multi-hit exception. This if fatal!
218 */
219
220 static void do_multihit(struct pt_regs *regs)
221 {
222 die("Caught multihit exception", regs, SIGKILL);
223 }
224
225 /*
226 * IRQ handler.
227 */
228
229 #if XTENSA_FAKE_NMI
230
231 #define IS_POW2(v) (((v) & ((v) - 1)) == 0)
232
233 #if !(PROFILING_INTLEVEL == XCHAL_EXCM_LEVEL && \
234 IS_POW2(XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL)))
235 #warning "Fake NMI is requested for PMM, but there are other IRQs at or above its level."
236 #warning "Fake NMI will be used, but there will be a bugcheck if one of those IRQs fire."
237
238 static inline void check_valid_nmi(void)
239 {
240 unsigned intread = xtensa_get_sr(interrupt);
241 unsigned intenable = xtensa_get_sr(intenable);
242
243 BUG_ON(intread & intenable &
244 ~(XTENSA_INTLEVEL_ANDBELOW_MASK(PROFILING_INTLEVEL) ^
245 XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL) ^
246 BIT(XCHAL_PROFILING_INTERRUPT)));
247 }
248
249 #else
250
251 static inline void check_valid_nmi(void)
252 {
253 }
254
255 #endif
256
257 irqreturn_t xtensa_pmu_irq_handler(int irq, void *dev_id);
258
259 DEFINE_PER_CPU(unsigned long, nmi_count);
260
261 static void do_nmi(struct pt_regs *regs)
262 {
263 struct pt_regs *old_regs = set_irq_regs(regs);
264
265 nmi_enter();
266 ++*this_cpu_ptr(&nmi_count);
267 check_valid_nmi();
268 xtensa_pmu_irq_handler(0, NULL);
269 nmi_exit();
270 set_irq_regs(old_regs);
271 }
272 #endif
273
274 static void do_interrupt(struct pt_regs *regs)
275 {
276 static const unsigned int_level_mask[] = {
277 0,
278 XCHAL_INTLEVEL1_MASK,
279 XCHAL_INTLEVEL2_MASK,
280 XCHAL_INTLEVEL3_MASK,
281 XCHAL_INTLEVEL4_MASK,
282 XCHAL_INTLEVEL5_MASK,
283 XCHAL_INTLEVEL6_MASK,
284 XCHAL_INTLEVEL7_MASK,
285 };
286 struct pt_regs *old_regs = set_irq_regs(regs);
287 unsigned unhandled = ~0u;
288
289 irq_enter();
290
291 for (;;) {
292 unsigned intread = xtensa_get_sr(interrupt);
293 unsigned intenable = xtensa_get_sr(intenable);
294 unsigned int_at_level = intread & intenable;
295 unsigned level;
296
297 for (level = LOCKLEVEL; level > 0; --level) {
298 if (int_at_level & int_level_mask[level]) {
299 int_at_level &= int_level_mask[level];
300 if (int_at_level & unhandled)
301 int_at_level &= unhandled;
302 else
303 unhandled |= int_level_mask[level];
304 break;
305 }
306 }
307
308 if (level == 0)
309 break;
310
311 /* clear lowest pending irq in the unhandled mask */
312 unhandled ^= (int_at_level & -int_at_level);
313 do_IRQ(__ffs(int_at_level), regs);
314 }
315
316 irq_exit();
317 set_irq_regs(old_regs);
318 }
319
320 static bool check_div0(struct pt_regs *regs)
321 {
322 static const u8 pattern[] = {'D', 'I', 'V', ''};
323 const u8 *p;
324 u8 buf[5];
325
326 if (user_mode(regs)) {
327 if (copy_from_user(buf, (void __user *)regs->pc + 2, 5))
328 return false;
329 p = buf;
330 } else {
331 p = (const u8 *)regs->pc + 2;
332 }
333
334 return memcmp(p, pattern, sizeof(pattern)) == 0 ||
335 memcmp(p + 1, pattern, sizeof(pattern)) == 0;
336 }
337
338 /*
339 * Illegal instruction. Fatal if in kernel space.
340 */
341
342 static void do_illegal_instruction(struct pt_regs *regs)
343 {
344 #ifdef CONFIG_USER_ABI_CALL0_PROBE
345 /*
346 * When call0 application encounters an illegal instruction fast
347 * exception handler will attempt to set PS.WOE and retry failing
348 * instruction.
349 * If we get here we know that that instruction is also illegal
350 * with PS.WOE set, so it's not related to the windowed option
351 * hence PS.WOE may be cleared.
352 */
353 if (regs->pc == current_thread_info()->ps_woe_fix_addr)
354 regs->ps &= ~PS_WOE_MASK;
355 #endif
356 if (check_div0(regs)) {
357 do_div0(regs);
358 return;
359 }
360
361 __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);
362
363 /* If in user mode, send SIGILL signal to current process. */
364
365 pr_info_ratelimited("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n",
366 current->comm, task_pid_nr(current), regs->pc);
367 force_sig(SIGILL);
368 }
369
370 static void do_div0(struct pt_regs *regs)
371 {
372 __die_if_kernel("Unhandled division by 0 in kernel", regs, SIGKILL);
373 force_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)regs->pc);
374 }
375
376 #ifdef CONFIG_XTENSA_LOAD_STORE
377 static void do_load_store(struct pt_regs *regs)
378 {
379 __die_if_kernel("Unhandled load/store exception in kernel",
380 regs, SIGKILL);
381
382 pr_info_ratelimited("Load/store error to %08lx in '%s' (pid = %d, pc = %#010lx)\n",
383 regs->excvaddr, current->comm,
384 task_pid_nr(current), regs->pc);
385 force_sig_fault(SIGBUS, BUS_ADRERR, (void *)regs->excvaddr);
386 }
387 #endif
388
389 /*
390 * Handle unaligned memory accesses from user space. Kill task.
391 *
392 * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory
393 * accesses causes from user space.
394 */
395
396 static void do_unaligned_user(struct pt_regs *regs)
397 {
398 __die_if_kernel("Unhandled unaligned exception in kernel",
399 regs, SIGKILL);
400
401 pr_info_ratelimited("Unaligned memory access to %08lx in '%s' "
402 "(pid = %d, pc = %#010lx)\n",
403 regs->excvaddr, current->comm,
404 task_pid_nr(current), regs->pc);
405 force_sig_fault(SIGBUS, BUS_ADRALN, (void *) regs->excvaddr);
406 }
407
408 #if XTENSA_HAVE_COPROCESSORS
409 static void do_coprocessor(struct pt_regs *regs)
410 {
411 coprocessor_flush_release_all(current_thread_info());
412 }
413 #endif
414
415 /* Handle debug events.
416 * When CONFIG_HAVE_HW_BREAKPOINT is on this handler is called with
417 * preemption disabled to avoid rescheduling and keep mapping of hardware
418 * breakpoint structures to debug registers intact, so that
419 * DEBUGCAUSE.DBNUM could be used in case of data breakpoint hit.
420 */
421 static void do_debug(struct pt_regs *regs)
422 {
423 #ifdef CONFIG_HAVE_HW_BREAKPOINT
424 int ret = check_hw_breakpoint(regs);
425
426 preempt_enable();
427 if (ret == 0)
428 return;
429 #endif
430 __die_if_kernel("Breakpoint in kernel", regs, SIGKILL);
431
432 /* If in user mode, send SIGTRAP signal to current process */
433
434 force_sig(SIGTRAP);
435 }
436
437
438 #define set_handler(type, cause, handler) \
439 do { \
440 unsigned int cpu; \
441 \
442 for_each_possible_cpu(cpu) \
443 per_cpu(exc_table, cpu).type[cause] = (handler);\
444 } while (0)
445
446 /* Set exception C handler - for temporary use when probing exceptions */
447
448 xtensa_exception_handler *
449 __init trap_set_handler(int cause, xtensa_exception_handler *handler)
450 {
451 void *previous = per_cpu(exc_table, 0).default_handler[cause];
452
453 set_handler(default_handler, cause, handler);
454 return previous;
455 }
456
457
458 static void trap_init_excsave(void)
459 {
460 xtensa_set_sr(this_cpu_ptr(&exc_table), excsave1);
461 }
462
463 static void trap_init_debug(void)
464 {
465 unsigned long debugsave = (unsigned long)this_cpu_ptr(&debug_table);
466
467 this_cpu_ptr(&debug_table)->debug_exception = debug_exception;
468 __asm__ __volatile__("wsr %0, excsave" __stringify(XCHAL_DEBUGLEVEL)
469 :: "a"(debugsave));
470 }
471
472 /*
473 * Initialize dispatch tables.
474 *
475 * The exception vectors are stored compressed the __init section in the
476 * dispatch_init_table. This function initializes the following three tables
477 * from that compressed table:
478 * - fast user first dispatch table for user exceptions
479 * - fast kernel first dispatch table for kernel exceptions
480 * - default C-handler C-handler called by the default fast handler.
481 *
482 * See vectors.S for more details.
483 */
484
485 void __init trap_init(void)
486 {
487 int i;
488
489 /* Setup default vectors. */
490
491 for (i = 0; i < EXCCAUSE_N; i++) {
492 set_handler(fast_user_handler, i, user_exception);
493 set_handler(fast_kernel_handler, i, kernel_exception);
494 set_handler(default_handler, i, do_unhandled);
495 }
496
497 /* Setup specific handlers. */
498
499 for(i = 0; dispatch_init_table[i].cause >= 0; i++) {
500 int fast = dispatch_init_table[i].fast;
501 int cause = dispatch_init_table[i].cause;
502 void *handler = dispatch_init_table[i].handler;
503
504 if (fast == 0)
505 set_handler(default_handler, cause, handler);
506 if ((fast & USER) != 0)
507 set_handler(fast_user_handler, cause, handler);
508 if ((fast & KRNL) != 0)
509 set_handler(fast_kernel_handler, cause, handler);
510 }
511
512 /* Initialize EXCSAVE_1 to hold the address of the exception table. */
513 trap_init_excsave();
514 trap_init_debug();
515 }
516
517 #ifdef CONFIG_SMP
518 void secondary_trap_init(void)
519 {
520 trap_init_excsave();
521 trap_init_debug();
522 }
523 #endif
524
525 /*
526 * This function dumps the current valid window frame and other base registers.
527 */
528
529 void show_regs(struct pt_regs * regs)
530 {
531 int i;
532
533 show_regs_print_info(KERN_DEFAULT);
534
535 for (i = 0; i < 16; i++) {
536 if ((i % 8) == 0)
537 pr_info("a%02d:", i);
538 pr_cont(" %08lx", regs->areg[i]);
539 }
540 pr_cont("\n");
541 pr_info("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n",
542 regs->pc, regs->ps, regs->depc, regs->excvaddr);
543 pr_info("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n",
544 regs->lbeg, regs->lend, regs->lcount, regs->sar);
545 if (user_mode(regs))
546 pr_cont("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n",
547 regs->windowbase, regs->windowstart, regs->wmask,
548 regs->syscall);
549 }
550
551 static int show_trace_cb(struct stackframe *frame, void *data)
552 {
553 const char *loglvl = data;
554
555 if (kernel_text_address(frame->pc))
556 printk("%s [<%08lx>] %pB\n",
557 loglvl, frame->pc, (void *)frame->pc);
558 return 0;
559 }
560
561 static void show_trace(struct task_struct *task, unsigned long *sp,
562 const char *loglvl)
563 {
564 if (!sp)
565 sp = stack_pointer(task);
566
567 printk("%sCall Trace:\n", loglvl);
568 walk_stackframe(sp, show_trace_cb, (void *)loglvl);
569 }
570
571 #define STACK_DUMP_ENTRY_SIZE 4
572 #define STACK_DUMP_LINE_SIZE 16
573 static size_t kstack_depth_to_print = CONFIG_PRINT_STACK_DEPTH;
574
575 struct stack_fragment
576 {
577 size_t len;
578 size_t off;
579 u8 *sp;
580 const char *loglvl;
581 };
582
583 static int show_stack_fragment_cb(struct stackframe *frame, void *data)
584 {
585 struct stack_fragment *sf = data;
586
587 while (sf->off < sf->len) {
588 u8 line[STACK_DUMP_LINE_SIZE];
589 size_t line_len = sf->len - sf->off > STACK_DUMP_LINE_SIZE ?
590 STACK_DUMP_LINE_SIZE : sf->len - sf->off;
591 bool arrow = sf->off == 0;
592
593 if (frame && frame->sp == (unsigned long)(sf->sp + sf->off))
594 arrow = true;
595
596 __memcpy(line, sf->sp + sf->off, line_len);
597 print_hex_dump(sf->loglvl, arrow ? "> " : " ", DUMP_PREFIX_NONE,
598 STACK_DUMP_LINE_SIZE, STACK_DUMP_ENTRY_SIZE,
599 line, line_len, false);
600 sf->off += STACK_DUMP_LINE_SIZE;
601 if (arrow)
602 return 0;
603 }
604 return 1;
605 }
606
607 void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
608 {
609 struct stack_fragment sf;
610
611 if (!sp)
612 sp = stack_pointer(task);
613
614 sf.len = min((-(size_t)sp) & (THREAD_SIZE - STACK_DUMP_ENTRY_SIZE),
615 kstack_depth_to_print * STACK_DUMP_ENTRY_SIZE);
616 sf.off = 0;
617 sf.sp = (u8 *)sp;
618 sf.loglvl = loglvl;
619
620 printk("%sStack:\n", loglvl);
621 walk_stackframe(sp, show_stack_fragment_cb, &sf);
622 while (sf.off < sf.len)
623 show_stack_fragment_cb(NULL, &sf);
624 show_trace(task, sp, loglvl);
625 }
626
627 DEFINE_SPINLOCK(die_lock);
628
629 void __noreturn die(const char * str, struct pt_regs * regs, long err)
630 {
631 static int die_counter;
632 const char *pr = "";
633
634 if (IS_ENABLED(CONFIG_PREEMPTION))
635 pr = IS_ENABLED(CONFIG_PREEMPT_RT) ? " PREEMPT_RT" : " PREEMPT";
636
637 console_verbose();
638 spin_lock_irq(&die_lock);
639
640 pr_info("%s: sig: %ld [#%d]%s\n", str, err, ++die_counter, pr);
641 show_regs(regs);
642 if (!user_mode(regs))
643 show_stack(NULL, (unsigned long *)regs->areg[1], KERN_INFO);
644
645 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
646 spin_unlock_irq(&die_lock);
647
648 if (in_interrupt())
649 panic("Fatal exception in interrupt");
650
651 if (panic_on_oops)
652 panic("Fatal exception");
653
654 make_task_dead(err);
655 }
656
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