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/kernel.h>
27 #include <linux/sched/signal.h>
28 #include <linux/sched/debug.h>
29 #include <linux/sched/task_stack.h>
30 #include <linux/init.h>
31 #include <linux/module.h>
32 #include <linux/stringify.h>
33 #include <linux/kallsyms.h>
34 #include <linux/delay.h>
35 #include <linux/hardirq.h>
36 #include <linux/ratelimit.h>
37
38 #include <asm/stacktrace.h>
39 #include <asm/ptrace.h>
40 #include <asm/timex.h>
41 #include <linux/uaccess.h>
42 #include <asm/pgtable.h>
43 #include <asm/processor.h>
44 #include <asm/traps.h>
45 #include <asm/hw_breakpoint.h>
46
47 /*
48 * Machine specific interrupt handlers
49 */
50
51 extern void kernel_exception(void);
52 extern void user_exception(void);
53
54 extern void fast_syscall_kernel(void);
55 extern void fast_syscall_user(void);
56 extern void fast_alloca(void);
57 extern void fast_unaligned(void);
58 extern void fast_second_level_miss(void);
59 extern void fast_store_prohibited(void);
60 extern void fast_coprocessor(void);
61
62 extern void do_illegal_instruction (struct pt_regs*);
63 extern void do_interrupt (struct pt_regs*);
64 extern void do_nmi(struct pt_regs *);
65 extern void do_unaligned_user (struct pt_regs*);
66 extern void do_multihit (struct pt_regs*, unsigned long);
67 extern void do_page_fault (struct pt_regs*, unsigned long);
68 extern void do_debug (struct pt_regs*);
69 extern void system_call (struct pt_regs*);
70
71 /*
72 * The vector table must be preceded by a save area (which
73 * implies it must be in RAM, unless one places RAM immediately
74 * before a ROM and puts the vector at the start of the ROM (!))
75 */
76
77 #define KRNL 0x01
78 #define USER 0x02
79
80 #define COPROCESSOR(x) \
81 { EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER, fast_coprocessor }
82
83 typedef struct {
84 int cause;
85 int fast;
86 void* handler;
87 } dispatch_init_table_t;
88
89 static dispatch_init_table_t __initdata dispatch_init_table[] = {
90
91 { EXCCAUSE_ILLEGAL_INSTRUCTION, 0, do_illegal_instruction},
92 { EXCCAUSE_SYSTEM_CALL, KRNL, fast_syscall_kernel },
93 { EXCCAUSE_SYSTEM_CALL, USER, fast_syscall_user },
94 { EXCCAUSE_SYSTEM_CALL, 0, system_call },
95 /* EXCCAUSE_INSTRUCTION_FETCH unhandled */
96 /* EXCCAUSE_LOAD_STORE_ERROR unhandled*/
97 { EXCCAUSE_LEVEL1_INTERRUPT, 0, do_interrupt },
98 { EXCCAUSE_ALLOCA, USER|KRNL, fast_alloca },
99 /* EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */
100 /* EXCCAUSE_PRIVILEGED unhandled */
101 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
102 #ifdef CONFIG_XTENSA_UNALIGNED_USER
103 { EXCCAUSE_UNALIGNED, USER, fast_unaligned },
104 #endif
105 { EXCCAUSE_UNALIGNED, 0, do_unaligned_user },
106 { EXCCAUSE_UNALIGNED, KRNL, fast_unaligned },
107 #endif
108 #ifdef CONFIG_MMU
109 { EXCCAUSE_ITLB_MISS, 0, do_page_fault },
110 { EXCCAUSE_ITLB_MISS, USER|KRNL, fast_second_level_miss},
111 { EXCCAUSE_ITLB_MULTIHIT, 0, do_multihit },
112 { EXCCAUSE_ITLB_PRIVILEGE, 0, do_page_fault },
113 /* EXCCAUSE_SIZE_RESTRICTION unhandled */
114 { EXCCAUSE_FETCH_CACHE_ATTRIBUTE, 0, do_page_fault },
115 { EXCCAUSE_DTLB_MISS, USER|KRNL, fast_second_level_miss},
116 { EXCCAUSE_DTLB_MISS, 0, do_page_fault },
117 { EXCCAUSE_DTLB_MULTIHIT, 0, do_multihit },
118 { EXCCAUSE_DTLB_PRIVILEGE, 0, do_page_fault },
119 /* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */
120 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, USER|KRNL, fast_store_prohibited },
121 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, 0, do_page_fault },
122 { EXCCAUSE_LOAD_CACHE_ATTRIBUTE, 0, do_page_fault },
123 #endif /* CONFIG_MMU */
124 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */
125 #if XTENSA_HAVE_COPROCESSOR(0)
126 COPROCESSOR(0),
127 #endif
128 #if XTENSA_HAVE_COPROCESSOR(1)
129 COPROCESSOR(1),
130 #endif
131 #if XTENSA_HAVE_COPROCESSOR(2)
132 COPROCESSOR(2),
133 #endif
134 #if XTENSA_HAVE_COPROCESSOR(3)
135 COPROCESSOR(3),
136 #endif
137 #if XTENSA_HAVE_COPROCESSOR(4)
138 COPROCESSOR(4),
139 #endif
140 #if XTENSA_HAVE_COPROCESSOR(5)
141 COPROCESSOR(5),
142 #endif
143 #if XTENSA_HAVE_COPROCESSOR(6)
144 COPROCESSOR(6),
145 #endif
146 #if XTENSA_HAVE_COPROCESSOR(7)
147 COPROCESSOR(7),
148 #endif
149 #if XTENSA_FAKE_NMI
150 { EXCCAUSE_MAPPED_NMI, 0, do_nmi },
151 #endif
152 { EXCCAUSE_MAPPED_DEBUG, 0, do_debug },
153 { -1, -1, 0 }
154
155 };
156
157 /* The exception table <exc_table> serves two functions:
158 * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c)
159 * 2. it is a temporary memory buffer for the exception handlers.
160 */
161
162 DEFINE_PER_CPU(struct exc_table, exc_table);
163 DEFINE_PER_CPU(struct debug_table, debug_table);
164
165 void die(const char*, struct pt_regs*, long);
166
167 static inline void
__die_if_kernel(const char * str,struct pt_regs * regs,long err)168 __die_if_kernel(const char *str, struct pt_regs *regs, long err)
169 {
170 if (!user_mode(regs))
171 die(str, regs, err);
172 }
173
174 /*
175 * Unhandled Exceptions. Kill user task or panic if in kernel space.
176 */
177
do_unhandled(struct pt_regs * regs,unsigned long exccause)178 void do_unhandled(struct pt_regs *regs, unsigned long exccause)
179 {
180 __die_if_kernel("Caught unhandled exception - should not happen",
181 regs, SIGKILL);
182
183 /* If in user mode, send SIGILL signal to current process */
184 pr_info_ratelimited("Caught unhandled exception in '%s' "
185 "(pid = %d, pc = %#010lx) - should not happen\n"
186 "\tEXCCAUSE is %ld\n",
187 current->comm, task_pid_nr(current), regs->pc,
188 exccause);
189 force_sig(SIGILL, current);
190 }
191
192 /*
193 * Multi-hit exception. This if fatal!
194 */
195
do_multihit(struct pt_regs * regs,unsigned long exccause)196 void do_multihit(struct pt_regs *regs, unsigned long exccause)
197 {
198 die("Caught multihit exception", regs, SIGKILL);
199 }
200
201 /*
202 * IRQ handler.
203 */
204
205 extern void do_IRQ(int, struct pt_regs *);
206
207 #if XTENSA_FAKE_NMI
208
209 #define IS_POW2(v) (((v) & ((v) - 1)) == 0)
210
211 #if !(PROFILING_INTLEVEL == XCHAL_EXCM_LEVEL && \
212 IS_POW2(XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL)))
213 #warning "Fake NMI is requested for PMM, but there are other IRQs at or above its level."
214 #warning "Fake NMI will be used, but there will be a bugcheck if one of those IRQs fire."
215
check_valid_nmi(void)216 static inline void check_valid_nmi(void)
217 {
218 unsigned intread = get_sr(interrupt);
219 unsigned intenable = get_sr(intenable);
220
221 BUG_ON(intread & intenable &
222 ~(XTENSA_INTLEVEL_ANDBELOW_MASK(PROFILING_INTLEVEL) ^
223 XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL) ^
224 BIT(XCHAL_PROFILING_INTERRUPT)));
225 }
226
227 #else
228
check_valid_nmi(void)229 static inline void check_valid_nmi(void)
230 {
231 }
232
233 #endif
234
235 irqreturn_t xtensa_pmu_irq_handler(int irq, void *dev_id);
236
237 DEFINE_PER_CPU(unsigned long, nmi_count);
238
do_nmi(struct pt_regs * regs)239 void do_nmi(struct pt_regs *regs)
240 {
241 struct pt_regs *old_regs;
242
243 if ((regs->ps & PS_INTLEVEL_MASK) < LOCKLEVEL)
244 trace_hardirqs_off();
245
246 old_regs = set_irq_regs(regs);
247 nmi_enter();
248 ++*this_cpu_ptr(&nmi_count);
249 check_valid_nmi();
250 xtensa_pmu_irq_handler(0, NULL);
251 nmi_exit();
252 set_irq_regs(old_regs);
253 }
254 #endif
255
do_interrupt(struct pt_regs * regs)256 void do_interrupt(struct pt_regs *regs)
257 {
258 static const unsigned int_level_mask[] = {
259 0,
260 XCHAL_INTLEVEL1_MASK,
261 XCHAL_INTLEVEL2_MASK,
262 XCHAL_INTLEVEL3_MASK,
263 XCHAL_INTLEVEL4_MASK,
264 XCHAL_INTLEVEL5_MASK,
265 XCHAL_INTLEVEL6_MASK,
266 XCHAL_INTLEVEL7_MASK,
267 };
268 struct pt_regs *old_regs;
269
270 trace_hardirqs_off();
271
272 old_regs = set_irq_regs(regs);
273 irq_enter();
274
275 for (;;) {
276 unsigned intread = get_sr(interrupt);
277 unsigned intenable = get_sr(intenable);
278 unsigned int_at_level = intread & intenable;
279 unsigned level;
280
281 for (level = LOCKLEVEL; level > 0; --level) {
282 if (int_at_level & int_level_mask[level]) {
283 int_at_level &= int_level_mask[level];
284 break;
285 }
286 }
287
288 if (level == 0)
289 break;
290
291 do_IRQ(__ffs(int_at_level), regs);
292 }
293
294 irq_exit();
295 set_irq_regs(old_regs);
296 }
297
298 /*
299 * Illegal instruction. Fatal if in kernel space.
300 */
301
302 void
do_illegal_instruction(struct pt_regs * regs)303 do_illegal_instruction(struct pt_regs *regs)
304 {
305 __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);
306
307 /* If in user mode, send SIGILL signal to current process. */
308
309 pr_info_ratelimited("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n",
310 current->comm, task_pid_nr(current), regs->pc);
311 force_sig(SIGILL, current);
312 }
313
314
315 /*
316 * Handle unaligned memory accesses from user space. Kill task.
317 *
318 * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory
319 * accesses causes from user space.
320 */
321
322 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
323 void
do_unaligned_user(struct pt_regs * regs)324 do_unaligned_user (struct pt_regs *regs)
325 {
326 __die_if_kernel("Unhandled unaligned exception in kernel",
327 regs, SIGKILL);
328
329 current->thread.bad_vaddr = regs->excvaddr;
330 current->thread.error_code = -3;
331 pr_info_ratelimited("Unaligned memory access to %08lx in '%s' "
332 "(pid = %d, pc = %#010lx)\n",
333 regs->excvaddr, current->comm,
334 task_pid_nr(current), regs->pc);
335 force_sig_fault(SIGBUS, BUS_ADRALN, (void *) regs->excvaddr, current);
336 }
337 #endif
338
339 /* Handle debug events.
340 * When CONFIG_HAVE_HW_BREAKPOINT is on this handler is called with
341 * preemption disabled to avoid rescheduling and keep mapping of hardware
342 * breakpoint structures to debug registers intact, so that
343 * DEBUGCAUSE.DBNUM could be used in case of data breakpoint hit.
344 */
345 void
do_debug(struct pt_regs * regs)346 do_debug(struct pt_regs *regs)
347 {
348 #ifdef CONFIG_HAVE_HW_BREAKPOINT
349 int ret = check_hw_breakpoint(regs);
350
351 preempt_enable();
352 if (ret == 0)
353 return;
354 #endif
355 __die_if_kernel("Breakpoint in kernel", regs, SIGKILL);
356
357 /* If in user mode, send SIGTRAP signal to current process */
358
359 force_sig(SIGTRAP, current);
360 }
361
362
363 #define set_handler(type, cause, handler) \
364 do { \
365 unsigned int cpu; \
366 \
367 for_each_possible_cpu(cpu) \
368 per_cpu(exc_table, cpu).type[cause] = (handler);\
369 } while (0)
370
371 /* Set exception C handler - for temporary use when probing exceptions */
372
trap_set_handler(int cause,void * handler)373 void * __init trap_set_handler(int cause, void *handler)
374 {
375 void *previous = per_cpu(exc_table, 0).default_handler[cause];
376
377 set_handler(default_handler, cause, handler);
378 return previous;
379 }
380
381
trap_init_excsave(void)382 static void trap_init_excsave(void)
383 {
384 unsigned long excsave1 = (unsigned long)this_cpu_ptr(&exc_table);
385 __asm__ __volatile__("wsr %0, excsave1\n" : : "a" (excsave1));
386 }
387
trap_init_debug(void)388 static void trap_init_debug(void)
389 {
390 unsigned long debugsave = (unsigned long)this_cpu_ptr(&debug_table);
391
392 this_cpu_ptr(&debug_table)->debug_exception = debug_exception;
393 __asm__ __volatile__("wsr %0, excsave" __stringify(XCHAL_DEBUGLEVEL)
394 :: "a"(debugsave));
395 }
396
397 /*
398 * Initialize dispatch tables.
399 *
400 * The exception vectors are stored compressed the __init section in the
401 * dispatch_init_table. This function initializes the following three tables
402 * from that compressed table:
403 * - fast user first dispatch table for user exceptions
404 * - fast kernel first dispatch table for kernel exceptions
405 * - default C-handler C-handler called by the default fast handler.
406 *
407 * See vectors.S for more details.
408 */
409
trap_init(void)410 void __init trap_init(void)
411 {
412 int i;
413
414 /* Setup default vectors. */
415
416 for (i = 0; i < EXCCAUSE_N; i++) {
417 set_handler(fast_user_handler, i, user_exception);
418 set_handler(fast_kernel_handler, i, kernel_exception);
419 set_handler(default_handler, i, do_unhandled);
420 }
421
422 /* Setup specific handlers. */
423
424 for(i = 0; dispatch_init_table[i].cause >= 0; i++) {
425
426 int fast = dispatch_init_table[i].fast;
427 int cause = dispatch_init_table[i].cause;
428 void *handler = dispatch_init_table[i].handler;
429
430 if (fast == 0)
431 set_handler(default_handler, cause, handler);
432 if (fast && fast & USER)
433 set_handler(fast_user_handler, cause, handler);
434 if (fast && fast & KRNL)
435 set_handler(fast_kernel_handler, cause, handler);
436 }
437
438 /* Initialize EXCSAVE_1 to hold the address of the exception table. */
439 trap_init_excsave();
440 trap_init_debug();
441 }
442
443 #ifdef CONFIG_SMP
secondary_trap_init(void)444 void secondary_trap_init(void)
445 {
446 trap_init_excsave();
447 trap_init_debug();
448 }
449 #endif
450
451 /*
452 * This function dumps the current valid window frame and other base registers.
453 */
454
show_regs(struct pt_regs * regs)455 void show_regs(struct pt_regs * regs)
456 {
457 int i, wmask;
458
459 show_regs_print_info(KERN_DEFAULT);
460
461 wmask = regs->wmask & ~1;
462
463 for (i = 0; i < 16; i++) {
464 if ((i % 8) == 0)
465 pr_info("a%02d:", i);
466 pr_cont(" %08lx", regs->areg[i]);
467 }
468 pr_cont("\n");
469 pr_info("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n",
470 regs->pc, regs->ps, regs->depc, regs->excvaddr);
471 pr_info("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n",
472 regs->lbeg, regs->lend, regs->lcount, regs->sar);
473 if (user_mode(regs))
474 pr_cont("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n",
475 regs->windowbase, regs->windowstart, regs->wmask,
476 regs->syscall);
477 }
478
show_trace_cb(struct stackframe * frame,void * data)479 static int show_trace_cb(struct stackframe *frame, void *data)
480 {
481 if (kernel_text_address(frame->pc))
482 pr_cont(" [<%08lx>] %pB\n", frame->pc, (void *)frame->pc);
483 return 0;
484 }
485
show_trace(struct task_struct * task,unsigned long * sp)486 void show_trace(struct task_struct *task, unsigned long *sp)
487 {
488 if (!sp)
489 sp = stack_pointer(task);
490
491 pr_info("Call Trace:\n");
492 walk_stackframe(sp, show_trace_cb, NULL);
493 #ifndef CONFIG_KALLSYMS
494 pr_cont("\n");
495 #endif
496 }
497
498 static int kstack_depth_to_print = 24;
499
show_stack(struct task_struct * task,unsigned long * sp)500 void show_stack(struct task_struct *task, unsigned long *sp)
501 {
502 int i = 0;
503 unsigned long *stack;
504
505 if (!sp)
506 sp = stack_pointer(task);
507 stack = sp;
508
509 pr_info("Stack:\n");
510
511 for (i = 0; i < kstack_depth_to_print; i++) {
512 if (kstack_end(sp))
513 break;
514 pr_cont(" %08lx", *sp++);
515 if (i % 8 == 7)
516 pr_cont("\n");
517 }
518 show_trace(task, stack);
519 }
520
521 DEFINE_SPINLOCK(die_lock);
522
die(const char * str,struct pt_regs * regs,long err)523 void die(const char * str, struct pt_regs * regs, long err)
524 {
525 static int die_counter;
526
527 console_verbose();
528 spin_lock_irq(&die_lock);
529
530 pr_info("%s: sig: %ld [#%d]%s\n", str, err, ++die_counter,
531 IS_ENABLED(CONFIG_PREEMPT) ? " PREEMPT" : "");
532 show_regs(regs);
533 if (!user_mode(regs))
534 show_stack(NULL, (unsigned long*)regs->areg[1]);
535
536 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
537 spin_unlock_irq(&die_lock);
538
539 if (in_interrupt())
540 panic("Fatal exception in interrupt");
541
542 if (panic_on_oops)
543 panic("Fatal exception");
544
545 do_exit(err);
546 }
547
