summaryrefslogtreecommitdiffstats
path: root/arch/xtensa/kernel/traps.c
blob: ce37d5b899fead50d312f06ed3c3f3982309d294 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
/*
 * arch/xtensa/kernel/traps.c
 *
 * Exception handling.
 *
 * Derived from code with the following copyrights:
 * Copyright (C) 1994 - 1999 by Ralf Baechle
 * Modified for R3000 by Paul M. Antoine, 1995, 1996
 * Complete output from die() by Ulf Carlsson, 1998
 * Copyright (C) 1999 Silicon Graphics, Inc.
 *
 * Essentially rewritten for the Xtensa architecture port.
 *
 * Copyright (C) 2001 - 2013 Tensilica Inc.
 *
 * Joe Taylor	<joe@tensilica.com, joetylr@yahoo.com>
 * Chris Zankel	<chris@zankel.net>
 * Marc Gauthier<marc@tensilica.com, marc@alumni.uwaterloo.ca>
 * Kevin Chea
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/stringify.h>
#include <linux/kallsyms.h>
#include <linux/delay.h>
#include <linux/hardirq.h>

#include <asm/stacktrace.h>
#include <asm/ptrace.h>
#include <asm/timex.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/traps.h>
#include <asm/hw_breakpoint.h>

/*
 * Machine specific interrupt handlers
 */

extern void kernel_exception(void);
extern void user_exception(void);

extern void fast_syscall_kernel(void);
extern void fast_syscall_user(void);
extern void fast_alloca(void);
extern void fast_unaligned(void);
extern void fast_second_level_miss(void);
extern void fast_store_prohibited(void);
extern void fast_coprocessor(void);

extern void do_illegal_instruction (struct pt_regs*);
extern void do_interrupt (struct pt_regs*);
extern void do_nmi(struct pt_regs *);
extern void do_unaligned_user (struct pt_regs*);
extern void do_multihit (struct pt_regs*, unsigned long);
extern void do_page_fault (struct pt_regs*, unsigned long);
extern void do_debug (struct pt_regs*);
extern void system_call (struct pt_regs*);

/*
 * The vector table must be preceded by a save area (which
 * implies it must be in RAM, unless one places RAM immediately
 * before a ROM and puts the vector at the start of the ROM (!))
 */

#define KRNL		0x01
#define USER		0x02

#define COPROCESSOR(x)							\
{ EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER, fast_coprocessor }

typedef struct {
	int cause;
	int fast;
	void* handler;
} dispatch_init_table_t;

static dispatch_init_table_t __initdata dispatch_init_table[] = {

{ EXCCAUSE_ILLEGAL_INSTRUCTION,	0,	   do_illegal_instruction},
{ EXCCAUSE_SYSTEM_CALL,		KRNL,	   fast_syscall_kernel },
{ EXCCAUSE_SYSTEM_CALL,		USER,	   fast_syscall_user },
{ EXCCAUSE_SYSTEM_CALL,		0,	   system_call },
/* EXCCAUSE_INSTRUCTION_FETCH unhandled */
/* EXCCAUSE_LOAD_STORE_ERROR unhandled*/
{ EXCCAUSE_LEVEL1_INTERRUPT,	0,	   do_interrupt },
{ EXCCAUSE_ALLOCA,		USER|KRNL, fast_alloca },
/* EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */
/* EXCCAUSE_PRIVILEGED unhandled */
#if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
#ifdef CONFIG_XTENSA_UNALIGNED_USER
{ EXCCAUSE_UNALIGNED,		USER,	   fast_unaligned },
#endif
{ EXCCAUSE_UNALIGNED,		0,	   do_unaligned_user },
{ EXCCAUSE_UNALIGNED,		KRNL,	   fast_unaligned },
#endif
#ifdef CONFIG_MMU
{ EXCCAUSE_ITLB_MISS,		0,	   do_page_fault },
{ EXCCAUSE_ITLB_MISS,		USER|KRNL, fast_second_level_miss},
{ EXCCAUSE_ITLB_MULTIHIT,		0,	   do_multihit },
{ EXCCAUSE_ITLB_PRIVILEGE,	0,	   do_page_fault },
/* EXCCAUSE_SIZE_RESTRICTION unhandled */
{ EXCCAUSE_FETCH_CACHE_ATTRIBUTE,	0,	   do_page_fault },
{ EXCCAUSE_DTLB_MISS,		USER|KRNL, fast_second_level_miss},
{ EXCCAUSE_DTLB_MISS,		0,	   do_page_fault },
{ EXCCAUSE_DTLB_MULTIHIT,		0,	   do_multihit },
{ EXCCAUSE_DTLB_PRIVILEGE,	0,	   do_page_fault },
/* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */
{ EXCCAUSE_STORE_CACHE_ATTRIBUTE,	USER|KRNL, fast_store_prohibited },
{ EXCCAUSE_STORE_CACHE_ATTRIBUTE,	0,	   do_page_fault },
{ EXCCAUSE_LOAD_CACHE_ATTRIBUTE,	0,	   do_page_fault },
#endif /* CONFIG_MMU */
/* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */
#if XTENSA_HAVE_COPROCESSOR(0)
COPROCESSOR(0),
#endif
#if XTENSA_HAVE_COPROCESSOR(1)
COPROCESSOR(1),
#endif
#if XTENSA_HAVE_COPROCESSOR(2)
COPROCESSOR(2),
#endif
#if XTENSA_HAVE_COPROCESSOR(3)
COPROCESSOR(3),
#endif
#if XTENSA_HAVE_COPROCESSOR(4)
COPROCESSOR(4),
#endif
#if XTENSA_HAVE_COPROCESSOR(5)
COPROCESSOR(5),
#endif
#if XTENSA_HAVE_COPROCESSOR(6)
COPROCESSOR(6),
#endif
#if XTENSA_HAVE_COPROCESSOR(7)
COPROCESSOR(7),
#endif
#if XTENSA_FAKE_NMI
{ EXCCAUSE_MAPPED_NMI,			0,		do_nmi },
#endif
{ EXCCAUSE_MAPPED_DEBUG,		0,		do_debug },
{ -1, -1, 0 }

};

/* The exception table <exc_table> serves two functions:
 * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c)
 * 2. it is a temporary memory buffer for the exception handlers.
 */

DEFINE_PER_CPU(unsigned long, exc_table[EXC_TABLE_SIZE/4]);

DEFINE_PER_CPU(struct debug_table, debug_table);

void die(const char*, struct pt_regs*, long);

static inline void
__die_if_kernel(const char *str, struct pt_regs *regs, long err)
{
	if (!user_mode(regs))
		die(str, regs, err);
}

/*
 * Unhandled Exceptions. Kill user task or panic if in kernel space.
 */

void do_unhandled(struct pt_regs *regs, unsigned long exccause)
{
	__die_if_kernel("Caught unhandled exception - should not happen",
	    		regs, SIGKILL);

	/* If in user mode, send SIGILL signal to current process */
	printk("Caught unhandled exception in '%s' "
	       "(pid = %d, pc = %#010lx) - should not happen\n"
	       "\tEXCCAUSE is %ld\n",
	       current->comm, task_pid_nr(current), regs->pc, exccause);
	force_sig(SIGILL, current);
}

/*
 * Multi-hit exception. This if fatal!
 */

void do_multihit(struct pt_regs *regs, unsigned long exccause)
{
	die("Caught multihit exception", regs, SIGKILL);
}

/*
 * IRQ handler.
 */

extern void do_IRQ(int, struct pt_regs *);

#if XTENSA_FAKE_NMI

#define IS_POW2(v) (((v) & ((v) - 1)) == 0)

#if !(PROFILING_INTLEVEL == XCHAL_EXCM_LEVEL && \
      IS_POW2(XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL)))
#warning "Fake NMI is requested for PMM, but there are other IRQs at or above its level."
#warning "Fake NMI will be used, but there will be a bugcheck if one of those IRQs fire."

static inline void check_valid_nmi(void)
{
	unsigned intread = get_sr(interrupt);
	unsigned intenable = get_sr(intenable);

	BUG_ON(intread & intenable &
	       ~(XTENSA_INTLEVEL_ANDBELOW_MASK(PROFILING_INTLEVEL) ^
		 XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL) ^
		 BIT(XCHAL_PROFILING_INTERRUPT)));
}

#else

static inline void check_valid_nmi(void)
{
}

#endif

irqreturn_t xtensa_pmu_irq_handler(int irq, void *dev_id);

DEFINE_PER_CPU(unsigned long, nmi_count);

void do_nmi(struct pt_regs *regs)
{
	struct pt_regs *old_regs;

	if ((regs->ps & PS_INTLEVEL_MASK) < LOCKLEVEL)
		trace_hardirqs_off();

	old_regs = set_irq_regs(regs);
	nmi_enter();
	++*this_cpu_ptr(&nmi_count);
	check_valid_nmi();
	xtensa_pmu_irq_handler(0, NULL);
	nmi_exit();
	set_irq_regs(old_regs);
}
#endif

void do_interrupt(struct pt_regs *regs)
{
	static const unsigned int_level_mask[] = {
		0,
		XCHAL_INTLEVEL1_MASK,
		XCHAL_INTLEVEL2_MASK,
		XCHAL_INTLEVEL3_MASK,
		XCHAL_INTLEVEL4_MASK,
		XCHAL_INTLEVEL5_MASK,
		XCHAL_INTLEVEL6_MASK,
		XCHAL_INTLEVEL7_MASK,
	};
	struct pt_regs *old_regs;

	trace_hardirqs_off();

	old_regs = set_irq_regs(regs);
	irq_enter();

	for (;;) {
		unsigned intread = get_sr(interrupt);
		unsigned intenable = get_sr(intenable);
		unsigned int_at_level = intread & intenable;
		unsigned level;

		for (level = LOCKLEVEL; level > 0; --level) {
			if (int_at_level & int_level_mask[level]) {
				int_at_level &= int_level_mask[level];
				break;
			}
		}

		if (level == 0)
			break;

		do_IRQ(__ffs(int_at_level), regs);
	}

	irq_exit();
	set_irq_regs(old_regs);
}

/*
 * Illegal instruction. Fatal if in kernel space.
 */

void
do_illegal_instruction(struct pt_regs *regs)
{
	__die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);

	/* If in user mode, send SIGILL signal to current process. */

	printk("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n",
	    current->comm, task_pid_nr(current), regs->pc);
	force_sig(SIGILL, current);
}


/*
 * Handle unaligned memory accesses from user space. Kill task.
 *
 * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory
 * accesses causes from user space.
 */

#if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
void
do_unaligned_user (struct pt_regs *regs)
{
	siginfo_t info;

	__die_if_kernel("Unhandled unaligned exception in kernel",
	    		regs, SIGKILL);

	current->thread.bad_vaddr = regs->excvaddr;
	current->thread.error_code = -3;
	printk("Unaligned memory access to %08lx in '%s' "
	       "(pid = %d, pc = %#010lx)\n",
	       regs->excvaddr, current->comm, task_pid_nr(current), regs->pc);
	info.si_signo = SIGBUS;
	info.si_errno = 0;
	info.si_code = BUS_ADRALN;
	info.si_addr = (void *) regs->excvaddr;
	force_sig_info(SIGSEGV, &info, current);

}
#endif

/* Handle debug events.
 * When CONFIG_HAVE_HW_BREAKPOINT is on this handler is called with
 * preemption disabled to avoid rescheduling and keep mapping of hardware
 * breakpoint structures to debug registers intact, so that
 * DEBUGCAUSE.DBNUM could be used in case of data breakpoint hit.
 */
void
do_debug(struct pt_regs *regs)
{
#ifdef CONFIG_HAVE_HW_BREAKPOINT
	int ret = check_hw_breakpoint(regs);

	preempt_enable();
	if (ret == 0)
		return;
#endif
	__die_if_kernel("Breakpoint in kernel", regs, SIGKILL);

	/* If in user mode, send SIGTRAP signal to current process */

	force_sig(SIGTRAP, current);
}


static void set_handler(int idx, void *handler)
{
	unsigned int cpu;

	for_each_possible_cpu(cpu)
		per_cpu(exc_table, cpu)[idx] = (unsigned long)handler;
}

/* Set exception C handler - for temporary use when probing exceptions */

void * __init trap_set_handler(int cause, void *handler)
{
	void *previous = (void *)per_cpu(exc_table, 0)[
		EXC_TABLE_DEFAULT / 4 + cause];
	set_handler(EXC_TABLE_DEFAULT / 4 + cause, handler);
	return previous;
}


static void trap_init_excsave(void)
{
	unsigned long excsave1 = (unsigned long)this_cpu_ptr(exc_table);
	__asm__ __volatile__("wsr  %0, excsave1\n" : : "a" (excsave1));
}

static void trap_init_debug(void)
{
	unsigned long debugsave = (unsigned long)this_cpu_ptr(&debug_table);

	this_cpu_ptr(&debug_table)->debug_exception = debug_exception;
	__asm__ __volatile__("wsr %0, excsave" __stringify(XCHAL_DEBUGLEVEL)
			     :: "a"(debugsave));
}

/*
 * Initialize dispatch tables.
 *
 * The exception vectors are stored compressed the __init section in the
 * dispatch_init_table. This function initializes the following three tables
 * from that compressed table:
 * - fast user		first dispatch table for user exceptions
 * - fast kernel	first dispatch table for kernel exceptions
 * - default C-handler	C-handler called by the default fast handler.
 *
 * See vectors.S for more details.
 */

void __init trap_init(void)
{
	int i;

	/* Setup default vectors. */

	for(i = 0; i < 64; i++) {
		set_handler(EXC_TABLE_FAST_USER/4   + i, user_exception);
		set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception);
		set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled);
	}

	/* Setup specific handlers. */

	for(i = 0; dispatch_init_table[i].cause >= 0; i++) {

		int fast = dispatch_init_table[i].fast;
		int cause = dispatch_init_table[i].cause;
		void *handler = dispatch_init_table[i].handler;

		if (fast == 0)
			set_handler (EXC_TABLE_DEFAULT/4 + cause, handler);
		if (fast && fast & USER)
			set_handler (EXC_TABLE_FAST_USER/4 + cause, handler);
		if (fast && fast & KRNL)
			set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler);
	}

	/* Initialize EXCSAVE_1 to hold the address of the exception table. */
	trap_init_excsave();
	trap_init_debug();
}

#ifdef CONFIG_SMP
void secondary_trap_init(void)
{
	trap_init_excsave();
	trap_init_debug();
}
#endif

/*
 * This function dumps the current valid window frame and other base registers.
 */

void show_regs(struct pt_regs * regs)
{
	int i, wmask;

	show_regs_print_info(KERN_DEFAULT);

	wmask = regs->wmask & ~1;

	for (i = 0; i < 16; i++) {
		if ((i % 8) == 0)
			pr_info("a%02d:", i);
		pr_cont(" %08lx", regs->areg[i]);
	}
	pr_cont("\n");
	pr_info("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n",
		regs->pc, regs->ps, regs->depc, regs->excvaddr);
	pr_info("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n",
		regs->lbeg, regs->lend, regs->lcount, regs->sar);
	if (user_mode(regs))
		pr_cont("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n",
			regs->windowbase, regs->windowstart, regs->wmask,
			regs->syscall);
}

static int show_trace_cb(struct stackframe *frame, void *data)
{
	if (kernel_text_address(frame->pc)) {
		pr_cont(" [<%08lx>]", frame->pc);
		print_symbol(" %s\n", frame->pc);
	}
	return 0;
}

void show_trace(struct task_struct *task, unsigned long *sp)
{
	if (!sp)
		sp = stack_pointer(task);

	pr_info("Call Trace:\n");
	walk_stackframe(sp, show_trace_cb, NULL);
#ifndef CONFIG_KALLSYMS
	pr_cont("\n");
#endif
}

static int kstack_depth_to_print = 24;

void show_stack(struct task_struct *task, unsigned long *sp)
{
	int i = 0;
	unsigned long *stack;

	if (!sp)
		sp = stack_pointer(task);
	stack = sp;

	pr_info("Stack:\n");

	for (i = 0; i < kstack_depth_to_print; i++) {
		if (kstack_end(sp))
			break;
		pr_cont(" %08lx", *sp++);
		if (i % 8 == 7)
			pr_cont("\n");
	}
	show_trace(task, stack);
}

DEFINE_SPINLOCK(die_lock);

void die(const char * str, struct pt_regs * regs, long err)
{
	static int die_counter;

	console_verbose();
	spin_lock_irq(&die_lock);

	pr_info("%s: sig: %ld [#%d]%s\n", str, err, ++die_counter,
		IS_ENABLED(CONFIG_PREEMPT) ? " PREEMPT" : "");
	show_regs(regs);
	if (!user_mode(regs))
		show_stack(NULL, (unsigned long*)regs->areg[1]);

	add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
	spin_unlock_irq(&die_lock);

	if (in_interrupt())
		panic("Fatal exception in interrupt");

	if (panic_on_oops)
		panic("Fatal exception");

	do_exit(err);
}