xref: /openbmc/linux/arch/xtensa/kernel/traps.c (revision abfbd895)
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.h>
28 #include <linux/init.h>
29 #include <linux/module.h>
30 #include <linux/stringify.h>
31 #include <linux/kallsyms.h>
32 #include <linux/delay.h>
33 #include <linux/hardirq.h>
34 
35 #include <asm/stacktrace.h>
36 #include <asm/ptrace.h>
37 #include <asm/timex.h>
38 #include <asm/uaccess.h>
39 #include <asm/pgtable.h>
40 #include <asm/processor.h>
41 #include <asm/traps.h>
42 
43 #ifdef CONFIG_KGDB
44 extern int gdb_enter;
45 extern int return_from_debug_flag;
46 #endif
47 
48 /*
49  * Machine specific interrupt handlers
50  */
51 
52 extern void kernel_exception(void);
53 extern void user_exception(void);
54 
55 extern void fast_syscall_kernel(void);
56 extern void fast_syscall_user(void);
57 extern void fast_alloca(void);
58 extern void fast_unaligned(void);
59 extern void fast_second_level_miss(void);
60 extern void fast_store_prohibited(void);
61 extern void fast_coprocessor(void);
62 
63 extern void do_illegal_instruction (struct pt_regs*);
64 extern void do_interrupt (struct pt_regs*);
65 extern void do_nmi(struct pt_regs *);
66 extern void do_unaligned_user (struct pt_regs*);
67 extern void do_multihit (struct pt_regs*, unsigned long);
68 extern void do_page_fault (struct pt_regs*, unsigned long);
69 extern void do_debug (struct pt_regs*);
70 extern void system_call (struct pt_regs*);
71 
72 /*
73  * The vector table must be preceded by a save area (which
74  * implies it must be in RAM, unless one places RAM immediately
75  * before a ROM and puts the vector at the start of the ROM (!))
76  */
77 
78 #define KRNL		0x01
79 #define USER		0x02
80 
81 #define COPROCESSOR(x)							\
82 { EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER, fast_coprocessor }
83 
84 typedef struct {
85 	int cause;
86 	int fast;
87 	void* handler;
88 } dispatch_init_table_t;
89 
90 static dispatch_init_table_t __initdata dispatch_init_table[] = {
91 
92 { EXCCAUSE_ILLEGAL_INSTRUCTION,	0,	   do_illegal_instruction},
93 { EXCCAUSE_SYSTEM_CALL,		KRNL,	   fast_syscall_kernel },
94 { EXCCAUSE_SYSTEM_CALL,		USER,	   fast_syscall_user },
95 { EXCCAUSE_SYSTEM_CALL,		0,	   system_call },
96 /* EXCCAUSE_INSTRUCTION_FETCH unhandled */
97 /* EXCCAUSE_LOAD_STORE_ERROR unhandled*/
98 { EXCCAUSE_LEVEL1_INTERRUPT,	0,	   do_interrupt },
99 { EXCCAUSE_ALLOCA,		USER|KRNL, fast_alloca },
100 /* EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */
101 /* EXCCAUSE_PRIVILEGED unhandled */
102 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
103 #ifdef CONFIG_XTENSA_UNALIGNED_USER
104 { EXCCAUSE_UNALIGNED,		USER,	   fast_unaligned },
105 #endif
106 { EXCCAUSE_UNALIGNED,		0,	   do_unaligned_user },
107 { EXCCAUSE_UNALIGNED,		KRNL,	   fast_unaligned },
108 #endif
109 #ifdef CONFIG_MMU
110 { EXCCAUSE_ITLB_MISS,		0,	   do_page_fault },
111 { EXCCAUSE_ITLB_MISS,		USER|KRNL, fast_second_level_miss},
112 { EXCCAUSE_ITLB_MULTIHIT,		0,	   do_multihit },
113 { EXCCAUSE_ITLB_PRIVILEGE,	0,	   do_page_fault },
114 /* EXCCAUSE_SIZE_RESTRICTION unhandled */
115 { EXCCAUSE_FETCH_CACHE_ATTRIBUTE,	0,	   do_page_fault },
116 { EXCCAUSE_DTLB_MISS,		USER|KRNL, fast_second_level_miss},
117 { EXCCAUSE_DTLB_MISS,		0,	   do_page_fault },
118 { EXCCAUSE_DTLB_MULTIHIT,		0,	   do_multihit },
119 { EXCCAUSE_DTLB_PRIVILEGE,	0,	   do_page_fault },
120 /* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */
121 { EXCCAUSE_STORE_CACHE_ATTRIBUTE,	USER|KRNL, fast_store_prohibited },
122 { EXCCAUSE_STORE_CACHE_ATTRIBUTE,	0,	   do_page_fault },
123 { EXCCAUSE_LOAD_CACHE_ATTRIBUTE,	0,	   do_page_fault },
124 #endif /* CONFIG_MMU */
125 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */
126 #if XTENSA_HAVE_COPROCESSOR(0)
127 COPROCESSOR(0),
128 #endif
129 #if XTENSA_HAVE_COPROCESSOR(1)
130 COPROCESSOR(1),
131 #endif
132 #if XTENSA_HAVE_COPROCESSOR(2)
133 COPROCESSOR(2),
134 #endif
135 #if XTENSA_HAVE_COPROCESSOR(3)
136 COPROCESSOR(3),
137 #endif
138 #if XTENSA_HAVE_COPROCESSOR(4)
139 COPROCESSOR(4),
140 #endif
141 #if XTENSA_HAVE_COPROCESSOR(5)
142 COPROCESSOR(5),
143 #endif
144 #if XTENSA_HAVE_COPROCESSOR(6)
145 COPROCESSOR(6),
146 #endif
147 #if XTENSA_HAVE_COPROCESSOR(7)
148 COPROCESSOR(7),
149 #endif
150 #if XTENSA_FAKE_NMI
151 { EXCCAUSE_MAPPED_NMI,			0,		do_nmi },
152 #endif
153 { EXCCAUSE_MAPPED_DEBUG,		0,		do_debug },
154 { -1, -1, 0 }
155 
156 };
157 
158 /* The exception table <exc_table> serves two functions:
159  * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c)
160  * 2. it is a temporary memory buffer for the exception handlers.
161  */
162 
163 DEFINE_PER_CPU(unsigned long, exc_table[EXC_TABLE_SIZE/4]);
164 
165 void die(const char*, struct pt_regs*, long);
166 
167 static inline void
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 
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 	printk("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, exccause);
188 	force_sig(SIGILL, current);
189 }
190 
191 /*
192  * Multi-hit exception. This if fatal!
193  */
194 
195 void do_multihit(struct pt_regs *regs, unsigned long exccause)
196 {
197 	die("Caught multihit exception", regs, SIGKILL);
198 }
199 
200 /*
201  * IRQ handler.
202  */
203 
204 extern void do_IRQ(int, struct pt_regs *);
205 
206 #if XTENSA_FAKE_NMI
207 
208 #define IS_POW2(v) (((v) & ((v) - 1)) == 0)
209 
210 #if !(PROFILING_INTLEVEL == XCHAL_EXCM_LEVEL && \
211       IS_POW2(XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL)))
212 #warning "Fake NMI is requested for PMM, but there are other IRQs at or above its level."
213 #warning "Fake NMI will be used, but there will be a bugcheck if one of those IRQs fire."
214 
215 static inline void check_valid_nmi(void)
216 {
217 	unsigned intread = get_sr(interrupt);
218 	unsigned intenable = get_sr(intenable);
219 
220 	BUG_ON(intread & intenable &
221 	       ~(XTENSA_INTLEVEL_ANDBELOW_MASK(PROFILING_INTLEVEL) ^
222 		 XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL) ^
223 		 BIT(XCHAL_PROFILING_INTERRUPT)));
224 }
225 
226 #else
227 
228 static inline void check_valid_nmi(void)
229 {
230 }
231 
232 #endif
233 
234 irqreturn_t xtensa_pmu_irq_handler(int irq, void *dev_id);
235 
236 DEFINE_PER_CPU(unsigned long, nmi_count);
237 
238 void do_nmi(struct pt_regs *regs)
239 {
240 	struct pt_regs *old_regs;
241 
242 	if ((regs->ps & PS_INTLEVEL_MASK) < LOCKLEVEL)
243 		trace_hardirqs_off();
244 
245 	old_regs = set_irq_regs(regs);
246 	nmi_enter();
247 	++*this_cpu_ptr(&nmi_count);
248 	check_valid_nmi();
249 	xtensa_pmu_irq_handler(0, NULL);
250 	nmi_exit();
251 	set_irq_regs(old_regs);
252 }
253 #endif
254 
255 void do_interrupt(struct pt_regs *regs)
256 {
257 	static const unsigned int_level_mask[] = {
258 		0,
259 		XCHAL_INTLEVEL1_MASK,
260 		XCHAL_INTLEVEL2_MASK,
261 		XCHAL_INTLEVEL3_MASK,
262 		XCHAL_INTLEVEL4_MASK,
263 		XCHAL_INTLEVEL5_MASK,
264 		XCHAL_INTLEVEL6_MASK,
265 		XCHAL_INTLEVEL7_MASK,
266 	};
267 	struct pt_regs *old_regs;
268 
269 	trace_hardirqs_off();
270 
271 	old_regs = set_irq_regs(regs);
272 	irq_enter();
273 
274 	for (;;) {
275 		unsigned intread = get_sr(interrupt);
276 		unsigned intenable = get_sr(intenable);
277 		unsigned int_at_level = intread & intenable;
278 		unsigned level;
279 
280 		for (level = LOCKLEVEL; level > 0; --level) {
281 			if (int_at_level & int_level_mask[level]) {
282 				int_at_level &= int_level_mask[level];
283 				break;
284 			}
285 		}
286 
287 		if (level == 0)
288 			break;
289 
290 		do_IRQ(__ffs(int_at_level), regs);
291 	}
292 
293 	irq_exit();
294 	set_irq_regs(old_regs);
295 }
296 
297 /*
298  * Illegal instruction. Fatal if in kernel space.
299  */
300 
301 void
302 do_illegal_instruction(struct pt_regs *regs)
303 {
304 	__die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);
305 
306 	/* If in user mode, send SIGILL signal to current process. */
307 
308 	printk("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n",
309 	    current->comm, task_pid_nr(current), regs->pc);
310 	force_sig(SIGILL, current);
311 }
312 
313 
314 /*
315  * Handle unaligned memory accesses from user space. Kill task.
316  *
317  * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory
318  * accesses causes from user space.
319  */
320 
321 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
322 void
323 do_unaligned_user (struct pt_regs *regs)
324 {
325 	siginfo_t info;
326 
327 	__die_if_kernel("Unhandled unaligned exception in kernel",
328 	    		regs, SIGKILL);
329 
330 	current->thread.bad_vaddr = regs->excvaddr;
331 	current->thread.error_code = -3;
332 	printk("Unaligned memory access to %08lx in '%s' "
333 	       "(pid = %d, pc = %#010lx)\n",
334 	       regs->excvaddr, current->comm, task_pid_nr(current), regs->pc);
335 	info.si_signo = SIGBUS;
336 	info.si_errno = 0;
337 	info.si_code = BUS_ADRALN;
338 	info.si_addr = (void *) regs->excvaddr;
339 	force_sig_info(SIGSEGV, &info, current);
340 
341 }
342 #endif
343 
344 void
345 do_debug(struct pt_regs *regs)
346 {
347 #ifdef CONFIG_KGDB
348 	/* If remote debugging is configured AND enabled, we give control to
349 	 * kgdb.  Otherwise, we fall through, perhaps giving control to the
350 	 * native debugger.
351 	 */
352 
353 	if (gdb_enter) {
354 		extern void gdb_handle_exception(struct pt_regs *);
355 		gdb_handle_exception(regs);
356 		return_from_debug_flag = 1;
357 		return;
358 	}
359 #endif
360 
361 	__die_if_kernel("Breakpoint in kernel", regs, SIGKILL);
362 
363 	/* If in user mode, send SIGTRAP signal to current process */
364 
365 	force_sig(SIGTRAP, current);
366 }
367 
368 
369 static void set_handler(int idx, void *handler)
370 {
371 	unsigned int cpu;
372 
373 	for_each_possible_cpu(cpu)
374 		per_cpu(exc_table, cpu)[idx] = (unsigned long)handler;
375 }
376 
377 /* Set exception C handler - for temporary use when probing exceptions */
378 
379 void * __init trap_set_handler(int cause, void *handler)
380 {
381 	void *previous = (void *)per_cpu(exc_table, 0)[
382 		EXC_TABLE_DEFAULT / 4 + cause];
383 	set_handler(EXC_TABLE_DEFAULT / 4 + cause, handler);
384 	return previous;
385 }
386 
387 
388 static void trap_init_excsave(void)
389 {
390 	unsigned long excsave1 = (unsigned long)this_cpu_ptr(exc_table);
391 	__asm__ __volatile__("wsr  %0, excsave1\n" : : "a" (excsave1));
392 }
393 
394 /*
395  * Initialize dispatch tables.
396  *
397  * The exception vectors are stored compressed the __init section in the
398  * dispatch_init_table. This function initializes the following three tables
399  * from that compressed table:
400  * - fast user		first dispatch table for user exceptions
401  * - fast kernel	first dispatch table for kernel exceptions
402  * - default C-handler	C-handler called by the default fast handler.
403  *
404  * See vectors.S for more details.
405  */
406 
407 void __init trap_init(void)
408 {
409 	int i;
410 
411 	/* Setup default vectors. */
412 
413 	for(i = 0; i < 64; i++) {
414 		set_handler(EXC_TABLE_FAST_USER/4   + i, user_exception);
415 		set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception);
416 		set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled);
417 	}
418 
419 	/* Setup specific handlers. */
420 
421 	for(i = 0; dispatch_init_table[i].cause >= 0; i++) {
422 
423 		int fast = dispatch_init_table[i].fast;
424 		int cause = dispatch_init_table[i].cause;
425 		void *handler = dispatch_init_table[i].handler;
426 
427 		if (fast == 0)
428 			set_handler (EXC_TABLE_DEFAULT/4 + cause, handler);
429 		if (fast && fast & USER)
430 			set_handler (EXC_TABLE_FAST_USER/4 + cause, handler);
431 		if (fast && fast & KRNL)
432 			set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler);
433 	}
434 
435 	/* Initialize EXCSAVE_1 to hold the address of the exception table. */
436 	trap_init_excsave();
437 }
438 
439 #ifdef CONFIG_SMP
440 void secondary_trap_init(void)
441 {
442 	trap_init_excsave();
443 }
444 #endif
445 
446 /*
447  * This function dumps the current valid window frame and other base registers.
448  */
449 
450 void show_regs(struct pt_regs * regs)
451 {
452 	int i, wmask;
453 
454 	show_regs_print_info(KERN_DEFAULT);
455 
456 	wmask = regs->wmask & ~1;
457 
458 	for (i = 0; i < 16; i++) {
459 		if ((i % 8) == 0)
460 			printk(KERN_INFO "a%02d:", i);
461 		printk(KERN_CONT " %08lx", regs->areg[i]);
462 	}
463 	printk(KERN_CONT "\n");
464 
465 	printk("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n",
466 	       regs->pc, regs->ps, regs->depc, regs->excvaddr);
467 	printk("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n",
468 	       regs->lbeg, regs->lend, regs->lcount, regs->sar);
469 	if (user_mode(regs))
470 		printk("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n",
471 		       regs->windowbase, regs->windowstart, regs->wmask,
472 		       regs->syscall);
473 }
474 
475 static int show_trace_cb(struct stackframe *frame, void *data)
476 {
477 	if (kernel_text_address(frame->pc)) {
478 		printk(" [<%08lx>] ", frame->pc);
479 		print_symbol("%s\n", frame->pc);
480 	}
481 	return 0;
482 }
483 
484 void show_trace(struct task_struct *task, unsigned long *sp)
485 {
486 	if (!sp)
487 		sp = stack_pointer(task);
488 
489 	printk("Call Trace:");
490 #ifdef CONFIG_KALLSYMS
491 	printk("\n");
492 #endif
493 	walk_stackframe(sp, show_trace_cb, NULL);
494 	printk("\n");
495 }
496 
497 /*
498  * This routine abuses get_user()/put_user() to reference pointers
499  * with at least a bit of error checking ...
500  */
501 
502 static int kstack_depth_to_print = 24;
503 
504 void show_stack(struct task_struct *task, unsigned long *sp)
505 {
506 	int i = 0;
507 	unsigned long *stack;
508 
509 	if (!sp)
510 		sp = stack_pointer(task);
511 	stack = sp;
512 
513 	printk("\nStack: ");
514 
515 	for (i = 0; i < kstack_depth_to_print; i++) {
516 		if (kstack_end(sp))
517 			break;
518 		if (i && ((i % 8) == 0))
519 			printk("\n       ");
520 		printk("%08lx ", *sp++);
521 	}
522 	printk("\n");
523 	show_trace(task, stack);
524 }
525 
526 void show_code(unsigned int *pc)
527 {
528 	long i;
529 
530 	printk("\nCode:");
531 
532 	for(i = -3 ; i < 6 ; i++) {
533 		unsigned long insn;
534 		if (__get_user(insn, pc + i)) {
535 			printk(" (Bad address in pc)\n");
536 			break;
537 		}
538 		printk("%c%08lx%c",(i?' ':'<'),insn,(i?' ':'>'));
539 	}
540 }
541 
542 DEFINE_SPINLOCK(die_lock);
543 
544 void die(const char * str, struct pt_regs * regs, long err)
545 {
546 	static int die_counter;
547 	int nl = 0;
548 
549 	console_verbose();
550 	spin_lock_irq(&die_lock);
551 
552 	printk("%s: sig: %ld [#%d]\n", str, err, ++die_counter);
553 #ifdef CONFIG_PREEMPT
554 	printk("PREEMPT ");
555 	nl = 1;
556 #endif
557 	if (nl)
558 		printk("\n");
559 	show_regs(regs);
560 	if (!user_mode(regs))
561 		show_stack(NULL, (unsigned long*)regs->areg[1]);
562 
563 	add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
564 	spin_unlock_irq(&die_lock);
565 
566 	if (in_interrupt())
567 		panic("Fatal exception in interrupt");
568 
569 	if (panic_on_oops)
570 		panic("Fatal exception");
571 
572 	do_exit(err);
573 }
574