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
44extern int gdb_enter;
45extern int return_from_debug_flag;
46#endif
47
48/*
49 * Machine specific interrupt handlers
50 */
51
52extern void kernel_exception(void);
53extern void user_exception(void);
54
55extern void fast_syscall_kernel(void);
56extern void fast_syscall_user(void);
57extern void fast_alloca(void);
58extern void fast_unaligned(void);
59extern void fast_second_level_miss(void);
60extern void fast_store_prohibited(void);
61extern void fast_coprocessor(void);
62
63extern void do_illegal_instruction (struct pt_regs*);
64extern void do_interrupt (struct pt_regs*);
65extern void do_nmi(struct pt_regs *);
66extern void do_unaligned_user (struct pt_regs*);
67extern void do_multihit (struct pt_regs*, unsigned long);
68extern void do_page_fault (struct pt_regs*, unsigned long);
69extern void do_debug (struct pt_regs*);
70extern 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
84typedef struct {
85	int cause;
86	int fast;
87	void* handler;
88} dispatch_init_table_t;
89
90static 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)
127COPROCESSOR(0),
128#endif
129#if XTENSA_HAVE_COPROCESSOR(1)
130COPROCESSOR(1),
131#endif
132#if XTENSA_HAVE_COPROCESSOR(2)
133COPROCESSOR(2),
134#endif
135#if XTENSA_HAVE_COPROCESSOR(3)
136COPROCESSOR(3),
137#endif
138#if XTENSA_HAVE_COPROCESSOR(4)
139COPROCESSOR(4),
140#endif
141#if XTENSA_HAVE_COPROCESSOR(5)
142COPROCESSOR(5),
143#endif
144#if XTENSA_HAVE_COPROCESSOR(6)
145COPROCESSOR(6),
146#endif
147#if XTENSA_HAVE_COPROCESSOR(7)
148COPROCESSOR(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
163DEFINE_PER_CPU(unsigned long, exc_table[EXC_TABLE_SIZE/4]);
164
165void die(const char*, struct pt_regs*, long);
166
167static 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
178void 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
195void 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
204extern void do_IRQ(int, struct pt_regs *);
205
206#if XTENSA_FAKE_NMI
207
208irqreturn_t xtensa_pmu_irq_handler(int irq, void *dev_id);
209
210DEFINE_PER_CPU(unsigned long, nmi_count);
211
212void do_nmi(struct pt_regs *regs)
213{
214	struct pt_regs *old_regs;
215
216	if ((regs->ps & PS_INTLEVEL_MASK) < LOCKLEVEL)
217		trace_hardirqs_off();
218
219	old_regs = set_irq_regs(regs);
220	nmi_enter();
221	++*this_cpu_ptr(&nmi_count);
222	xtensa_pmu_irq_handler(0, NULL);
223	nmi_exit();
224	set_irq_regs(old_regs);
225}
226#endif
227
228void do_interrupt(struct pt_regs *regs)
229{
230	static const unsigned int_level_mask[] = {
231		0,
232		XCHAL_INTLEVEL1_MASK,
233		XCHAL_INTLEVEL2_MASK,
234		XCHAL_INTLEVEL3_MASK,
235		XCHAL_INTLEVEL4_MASK,
236		XCHAL_INTLEVEL5_MASK,
237		XCHAL_INTLEVEL6_MASK,
238		XCHAL_INTLEVEL7_MASK,
239	};
240	struct pt_regs *old_regs;
241
242	trace_hardirqs_off();
243
244	old_regs = set_irq_regs(regs);
245	irq_enter();
246
247	for (;;) {
248		unsigned intread = get_sr(interrupt);
249		unsigned intenable = get_sr(intenable);
250		unsigned int_at_level = intread & intenable;
251		unsigned level;
252
253		for (level = LOCKLEVEL; level > 0; --level) {
254			if (int_at_level & int_level_mask[level]) {
255				int_at_level &= int_level_mask[level];
256				break;
257			}
258		}
259
260		if (level == 0)
261			break;
262
263		do_IRQ(__ffs(int_at_level), regs);
264	}
265
266	irq_exit();
267	set_irq_regs(old_regs);
268}
269
270/*
271 * Illegal instruction. Fatal if in kernel space.
272 */
273
274void
275do_illegal_instruction(struct pt_regs *regs)
276{
277	__die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);
278
279	/* If in user mode, send SIGILL signal to current process. */
280
281	printk("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n",
282	    current->comm, task_pid_nr(current), regs->pc);
283	force_sig(SIGILL, current);
284}
285
286
287/*
288 * Handle unaligned memory accesses from user space. Kill task.
289 *
290 * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory
291 * accesses causes from user space.
292 */
293
294#if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
295void
296do_unaligned_user (struct pt_regs *regs)
297{
298	siginfo_t info;
299
300	__die_if_kernel("Unhandled unaligned exception in kernel",
301	    		regs, SIGKILL);
302
303	current->thread.bad_vaddr = regs->excvaddr;
304	current->thread.error_code = -3;
305	printk("Unaligned memory access to %08lx in '%s' "
306	       "(pid = %d, pc = %#010lx)\n",
307	       regs->excvaddr, current->comm, task_pid_nr(current), regs->pc);
308	info.si_signo = SIGBUS;
309	info.si_errno = 0;
310	info.si_code = BUS_ADRALN;
311	info.si_addr = (void *) regs->excvaddr;
312	force_sig_info(SIGSEGV, &info, current);
313
314}
315#endif
316
317void
318do_debug(struct pt_regs *regs)
319{
320#ifdef CONFIG_KGDB
321	/* If remote debugging is configured AND enabled, we give control to
322	 * kgdb.  Otherwise, we fall through, perhaps giving control to the
323	 * native debugger.
324	 */
325
326	if (gdb_enter) {
327		extern void gdb_handle_exception(struct pt_regs *);
328		gdb_handle_exception(regs);
329		return_from_debug_flag = 1;
330		return;
331	}
332#endif
333
334	__die_if_kernel("Breakpoint in kernel", regs, SIGKILL);
335
336	/* If in user mode, send SIGTRAP signal to current process */
337
338	force_sig(SIGTRAP, current);
339}
340
341
342static void set_handler(int idx, void *handler)
343{
344	unsigned int cpu;
345
346	for_each_possible_cpu(cpu)
347		per_cpu(exc_table, cpu)[idx] = (unsigned long)handler;
348}
349
350/* Set exception C handler - for temporary use when probing exceptions */
351
352void * __init trap_set_handler(int cause, void *handler)
353{
354	void *previous = (void *)per_cpu(exc_table, 0)[
355		EXC_TABLE_DEFAULT / 4 + cause];
356	set_handler(EXC_TABLE_DEFAULT / 4 + cause, handler);
357	return previous;
358}
359
360
361static void trap_init_excsave(void)
362{
363	unsigned long excsave1 = (unsigned long)this_cpu_ptr(exc_table);
364	__asm__ __volatile__("wsr  %0, excsave1\n" : : "a" (excsave1));
365}
366
367/*
368 * Initialize dispatch tables.
369 *
370 * The exception vectors are stored compressed the __init section in the
371 * dispatch_init_table. This function initializes the following three tables
372 * from that compressed table:
373 * - fast user		first dispatch table for user exceptions
374 * - fast kernel	first dispatch table for kernel exceptions
375 * - default C-handler	C-handler called by the default fast handler.
376 *
377 * See vectors.S for more details.
378 */
379
380void __init trap_init(void)
381{
382	int i;
383
384	/* Setup default vectors. */
385
386	for(i = 0; i < 64; i++) {
387		set_handler(EXC_TABLE_FAST_USER/4   + i, user_exception);
388		set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception);
389		set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled);
390	}
391
392	/* Setup specific handlers. */
393
394	for(i = 0; dispatch_init_table[i].cause >= 0; i++) {
395
396		int fast = dispatch_init_table[i].fast;
397		int cause = dispatch_init_table[i].cause;
398		void *handler = dispatch_init_table[i].handler;
399
400		if (fast == 0)
401			set_handler (EXC_TABLE_DEFAULT/4 + cause, handler);
402		if (fast && fast & USER)
403			set_handler (EXC_TABLE_FAST_USER/4 + cause, handler);
404		if (fast && fast & KRNL)
405			set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler);
406	}
407
408	/* Initialize EXCSAVE_1 to hold the address of the exception table. */
409	trap_init_excsave();
410}
411
412#ifdef CONFIG_SMP
413void secondary_trap_init(void)
414{
415	trap_init_excsave();
416}
417#endif
418
419/*
420 * This function dumps the current valid window frame and other base registers.
421 */
422
423void show_regs(struct pt_regs * regs)
424{
425	int i, wmask;
426
427	show_regs_print_info(KERN_DEFAULT);
428
429	wmask = regs->wmask & ~1;
430
431	for (i = 0; i < 16; i++) {
432		if ((i % 8) == 0)
433			printk(KERN_INFO "a%02d:", i);
434		printk(KERN_CONT " %08lx", regs->areg[i]);
435	}
436	printk(KERN_CONT "\n");
437
438	printk("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n",
439	       regs->pc, regs->ps, regs->depc, regs->excvaddr);
440	printk("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n",
441	       regs->lbeg, regs->lend, regs->lcount, regs->sar);
442	if (user_mode(regs))
443		printk("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n",
444		       regs->windowbase, regs->windowstart, regs->wmask,
445		       regs->syscall);
446}
447
448static int show_trace_cb(struct stackframe *frame, void *data)
449{
450	if (kernel_text_address(frame->pc)) {
451		printk(" [<%08lx>] ", frame->pc);
452		print_symbol("%s\n", frame->pc);
453	}
454	return 0;
455}
456
457void show_trace(struct task_struct *task, unsigned long *sp)
458{
459	if (!sp)
460		sp = stack_pointer(task);
461
462	printk("Call Trace:");
463#ifdef CONFIG_KALLSYMS
464	printk("\n");
465#endif
466	walk_stackframe(sp, show_trace_cb, NULL);
467	printk("\n");
468}
469
470/*
471 * This routine abuses get_user()/put_user() to reference pointers
472 * with at least a bit of error checking ...
473 */
474
475static int kstack_depth_to_print = 24;
476
477void show_stack(struct task_struct *task, unsigned long *sp)
478{
479	int i = 0;
480	unsigned long *stack;
481
482	if (!sp)
483		sp = stack_pointer(task);
484	stack = sp;
485
486	printk("\nStack: ");
487
488	for (i = 0; i < kstack_depth_to_print; i++) {
489		if (kstack_end(sp))
490			break;
491		if (i && ((i % 8) == 0))
492			printk("\n       ");
493		printk("%08lx ", *sp++);
494	}
495	printk("\n");
496	show_trace(task, stack);
497}
498
499void show_code(unsigned int *pc)
500{
501	long i;
502
503	printk("\nCode:");
504
505	for(i = -3 ; i < 6 ; i++) {
506		unsigned long insn;
507		if (__get_user(insn, pc + i)) {
508			printk(" (Bad address in pc)\n");
509			break;
510		}
511		printk("%c%08lx%c",(i?' ':'<'),insn,(i?' ':'>'));
512	}
513}
514
515DEFINE_SPINLOCK(die_lock);
516
517void die(const char * str, struct pt_regs * regs, long err)
518{
519	static int die_counter;
520	int nl = 0;
521
522	console_verbose();
523	spin_lock_irq(&die_lock);
524
525	printk("%s: sig: %ld [#%d]\n", str, err, ++die_counter);
526#ifdef CONFIG_PREEMPT
527	printk("PREEMPT ");
528	nl = 1;
529#endif
530	if (nl)
531		printk("\n");
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