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 - 2005 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/ptrace.h>
36 #include <asm/timex.h>
37 #include <asm/uaccess.h>
38 #include <asm/pgtable.h>
39 #include <asm/processor.h>
40
41 #ifdef CONFIG_KGDB
42 extern int gdb_enter;
43 extern int return_from_debug_flag;
44 #endif
45
46 /*
47 * Machine specific interrupt handlers
48 */
49
50 extern void kernel_exception(void);
51 extern void user_exception(void);
52
53 extern void fast_syscall_kernel(void);
54 extern void fast_syscall_user(void);
55 extern void fast_alloca(void);
56 extern void fast_unaligned(void);
57 extern void fast_second_level_miss(void);
58 extern void fast_store_prohibited(void);
59 extern void fast_coprocessor(void);
60
61 extern void do_illegal_instruction (struct pt_regs*);
62 extern void do_interrupt (struct pt_regs*);
63 extern void do_unaligned_user (struct pt_regs*);
64 extern void do_multihit (struct pt_regs*, unsigned long);
65 extern void do_page_fault (struct pt_regs*, unsigned long);
66 extern void do_debug (struct pt_regs*);
67 extern void system_call (struct pt_regs*);
68
69 /*
70 * The vector table must be preceded by a save area (which
71 * implies it must be in RAM, unless one places RAM immediately
72 * before a ROM and puts the vector at the start of the ROM (!))
73 */
74
75 #define KRNL 0x01
76 #define USER 0x02
77
78 #define COPROCESSOR(x) \
79 { EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER, fast_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 { EXCCAUSE_ILLEGAL_INSTRUCTION, 0, do_illegal_instruction},
90 { EXCCAUSE_SYSTEM_CALL, KRNL, fast_syscall_kernel },
91 { EXCCAUSE_SYSTEM_CALL, USER, fast_syscall_user },
92 { EXCCAUSE_SYSTEM_CALL, 0, system_call },
93 /* EXCCAUSE_INSTRUCTION_FETCH unhandled */
94 /* EXCCAUSE_LOAD_STORE_ERROR unhandled*/
95 { EXCCAUSE_LEVEL1_INTERRUPT, 0, do_interrupt },
96 { EXCCAUSE_ALLOCA, USER|KRNL, fast_alloca },
97 /* EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */
98 /* EXCCAUSE_PRIVILEGED unhandled */
99 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
100 #ifdef CONFIG_UNALIGNED_USER
101 { EXCCAUSE_UNALIGNED, USER, fast_unaligned },
102 #else
103 { EXCCAUSE_UNALIGNED, 0, do_unaligned_user },
104 #endif
105 { EXCCAUSE_UNALIGNED, KRNL, fast_unaligned },
106 #endif
107 #ifdef CONFIG_MMU
108 { EXCCAUSE_ITLB_MISS, 0, do_page_fault },
109 { EXCCAUSE_ITLB_MISS, USER|KRNL, fast_second_level_miss},
110 { EXCCAUSE_ITLB_MULTIHIT, 0, do_multihit },
111 { EXCCAUSE_ITLB_PRIVILEGE, 0, do_page_fault },
112 /* EXCCAUSE_SIZE_RESTRICTION unhandled */
113 { EXCCAUSE_FETCH_CACHE_ATTRIBUTE, 0, do_page_fault },
114 { EXCCAUSE_DTLB_MISS, USER|KRNL, fast_second_level_miss},
115 { EXCCAUSE_DTLB_MISS, 0, do_page_fault },
116 { EXCCAUSE_DTLB_MULTIHIT, 0, do_multihit },
117 { EXCCAUSE_DTLB_PRIVILEGE, 0, do_page_fault },
118 /* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */
119 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, USER|KRNL, fast_store_prohibited },
120 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, 0, do_page_fault },
121 { EXCCAUSE_LOAD_CACHE_ATTRIBUTE, 0, do_page_fault },
122 #endif /* CONFIG_MMU */
123 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */
124 #if XTENSA_HAVE_COPROCESSOR(0)
125 COPROCESSOR(0),
126 #endif
127 #if XTENSA_HAVE_COPROCESSOR(1)
128 COPROCESSOR(1),
129 #endif
130 #if XTENSA_HAVE_COPROCESSOR(2)
131 COPROCESSOR(2),
132 #endif
133 #if XTENSA_HAVE_COPROCESSOR(3)
134 COPROCESSOR(3),
135 #endif
136 #if XTENSA_HAVE_COPROCESSOR(4)
137 COPROCESSOR(4),
138 #endif
139 #if XTENSA_HAVE_COPROCESSOR(5)
140 COPROCESSOR(5),
141 #endif
142 #if XTENSA_HAVE_COPROCESSOR(6)
143 COPROCESSOR(6),
144 #endif
145 #if XTENSA_HAVE_COPROCESSOR(7)
146 COPROCESSOR(7),
147 #endif
148 { EXCCAUSE_MAPPED_DEBUG, 0, do_debug },
149 { -1, -1, 0 }
150
151 };
152
153 /* The exception table <exc_table> serves two functions:
154 * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c)
155 * 2. it is a temporary memory buffer for the exception handlers.
156 */
157
158 unsigned long exc_table[EXC_TABLE_SIZE/4];
159
160 void die(const char*, struct pt_regs*, long);
161
162 static inline void
__die_if_kernel(const char * str,struct pt_regs * regs,long err)163 __die_if_kernel(const char *str, struct pt_regs *regs, long err)
164 {
165 if (!user_mode(regs))
166 die(str, regs, err);
167 }
168
169 /*
170 * Unhandled Exceptions. Kill user task or panic if in kernel space.
171 */
172
do_unhandled(struct pt_regs * regs,unsigned long exccause)173 void do_unhandled(struct pt_regs *regs, unsigned long exccause)
174 {
175 __die_if_kernel("Caught unhandled exception - should not happen",
176 regs, SIGKILL);
177
178 /* If in user mode, send SIGILL signal to current process */
179 printk("Caught unhandled exception in '%s' "
180 "(pid = %d, pc = %#010lx) - should not happen\n"
181 "\tEXCCAUSE is %ld\n",
182 current->comm, task_pid_nr(current), regs->pc, exccause);
183 force_sig(SIGILL, current);
184 }
185
186 /*
187 * Multi-hit exception. This if fatal!
188 */
189
do_multihit(struct pt_regs * regs,unsigned long exccause)190 void do_multihit(struct pt_regs *regs, unsigned long exccause)
191 {
192 die("Caught multihit exception", regs, SIGKILL);
193 }
194
195 /*
196 * Level-1 interrupt.
197 * We currently have no priority encoding.
198 */
199
200 unsigned long ignored_level1_interrupts;
201 extern void do_IRQ(int, struct pt_regs *);
202
do_interrupt(struct pt_regs * regs)203 void do_interrupt (struct pt_regs *regs)
204 {
205 unsigned long intread = get_sr (INTREAD);
206 unsigned long intenable = get_sr (INTENABLE);
207 int i, mask;
208
209 /* Handle all interrupts (no priorities).
210 * (Clear the interrupt before processing, in case it's
211 * edge-triggered or software-generated)
212 */
213
214 for (i=0, mask = 1; i < XCHAL_NUM_INTERRUPTS; i++, mask <<= 1) {
215 if (mask & (intread & intenable)) {
216 set_sr (mask, INTCLEAR);
217 do_IRQ (i,regs);
218 }
219 }
220 }
221
222 /*
223 * Illegal instruction. Fatal if in kernel space.
224 */
225
226 void
do_illegal_instruction(struct pt_regs * regs)227 do_illegal_instruction(struct pt_regs *regs)
228 {
229 __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);
230
231 /* If in user mode, send SIGILL signal to current process. */
232
233 printk("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n",
234 current->comm, task_pid_nr(current), regs->pc);
235 force_sig(SIGILL, current);
236 }
237
238
239 /*
240 * Handle unaligned memory accesses from user space. Kill task.
241 *
242 * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory
243 * accesses causes from user space.
244 */
245
246 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
247 #ifndef CONFIG_UNALIGNED_USER
248 void
do_unaligned_user(struct pt_regs * regs)249 do_unaligned_user (struct pt_regs *regs)
250 {
251 siginfo_t info;
252
253 __die_if_kernel("Unhandled unaligned exception in kernel",
254 regs, SIGKILL);
255
256 current->thread.bad_vaddr = regs->excvaddr;
257 current->thread.error_code = -3;
258 printk("Unaligned memory access to %08lx in '%s' "
259 "(pid = %d, pc = %#010lx)\n",
260 regs->excvaddr, current->comm, task_pid_nr(current), regs->pc);
261 info.si_signo = SIGBUS;
262 info.si_errno = 0;
263 info.si_code = BUS_ADRALN;
264 info.si_addr = (void *) regs->excvaddr;
265 force_sig_info(SIGSEGV, &info, current);
266
267 }
268 #endif
269 #endif
270
271 void
do_debug(struct pt_regs * regs)272 do_debug(struct pt_regs *regs)
273 {
274 #ifdef CONFIG_KGDB
275 /* If remote debugging is configured AND enabled, we give control to
276 * kgdb. Otherwise, we fall through, perhaps giving control to the
277 * native debugger.
278 */
279
280 if (gdb_enter) {
281 extern void gdb_handle_exception(struct pt_regs *);
282 gdb_handle_exception(regs);
283 return_from_debug_flag = 1;
284 return;
285 }
286 #endif
287
288 __die_if_kernel("Breakpoint in kernel", regs, SIGKILL);
289
290 /* If in user mode, send SIGTRAP signal to current process */
291
292 force_sig(SIGTRAP, current);
293 }
294
295
296 /*
297 * Initialize dispatch tables.
298 *
299 * The exception vectors are stored compressed the __init section in the
300 * dispatch_init_table. This function initializes the following three tables
301 * from that compressed table:
302 * - fast user first dispatch table for user exceptions
303 * - fast kernel first dispatch table for kernel exceptions
304 * - default C-handler C-handler called by the default fast handler.
305 *
306 * See vectors.S for more details.
307 */
308
309 #define set_handler(idx,handler) (exc_table[idx] = (unsigned long) (handler))
310
trap_init(void)311 void __init trap_init(void)
312 {
313 int i;
314
315 /* Setup default vectors. */
316
317 for(i = 0; i < 64; i++) {
318 set_handler(EXC_TABLE_FAST_USER/4 + i, user_exception);
319 set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception);
320 set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled);
321 }
322
323 /* Setup specific handlers. */
324
325 for(i = 0; dispatch_init_table[i].cause >= 0; i++) {
326
327 int fast = dispatch_init_table[i].fast;
328 int cause = dispatch_init_table[i].cause;
329 void *handler = dispatch_init_table[i].handler;
330
331 if (fast == 0)
332 set_handler (EXC_TABLE_DEFAULT/4 + cause, handler);
333 if (fast && fast & USER)
334 set_handler (EXC_TABLE_FAST_USER/4 + cause, handler);
335 if (fast && fast & KRNL)
336 set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler);
337 }
338
339 /* Initialize EXCSAVE_1 to hold the address of the exception table. */
340
341 i = (unsigned long)exc_table;
342 __asm__ __volatile__("wsr %0, "__stringify(EXCSAVE_1)"\n" : : "a" (i));
343 }
344
345 /*
346 * This function dumps the current valid window frame and other base registers.
347 */
348
show_regs(struct pt_regs * regs)349 void show_regs(struct pt_regs * regs)
350 {
351 int i, wmask;
352
353 wmask = regs->wmask & ~1;
354
355 for (i = 0; i < 16; i++) {
356 if ((i % 8) == 0)
357 printk(KERN_INFO "a%02d:", i);
358 printk(KERN_CONT " %08lx", regs->areg[i]);
359 }
360 printk(KERN_CONT "\n");
361
362 printk("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n",
363 regs->pc, regs->ps, regs->depc, regs->excvaddr);
364 printk("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n",
365 regs->lbeg, regs->lend, regs->lcount, regs->sar);
366 if (user_mode(regs))
367 printk("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n",
368 regs->windowbase, regs->windowstart, regs->wmask,
369 regs->syscall);
370 }
371
stack_pointer(struct task_struct * task)372 static __always_inline unsigned long *stack_pointer(struct task_struct *task)
373 {
374 unsigned long *sp;
375
376 if (!task || task == current)
377 __asm__ __volatile__ ("mov %0, a1\n" : "=a"(sp));
378 else
379 sp = (unsigned long *)task->thread.sp;
380
381 return sp;
382 }
383
spill_registers(void)384 static inline void spill_registers(void)
385 {
386 unsigned int a0, ps;
387
388 __asm__ __volatile__ (
389 "movi a14," __stringify (PS_EXCM_BIT) " | 1\n\t"
390 "mov a12, a0\n\t"
391 "rsr a13," __stringify(SAR) "\n\t"
392 "xsr a14," __stringify(PS) "\n\t"
393 "movi a0, _spill_registers\n\t"
394 "rsync\n\t"
395 "callx0 a0\n\t"
396 "mov a0, a12\n\t"
397 "wsr a13," __stringify(SAR) "\n\t"
398 "wsr a14," __stringify(PS) "\n\t"
399 :: "a" (&a0), "a" (&ps)
400 : "a2", "a3", "a4", "a7", "a11", "a12", "a13", "a14", "a15", "memory");
401 }
402
show_trace(struct task_struct * task,unsigned long * sp)403 void show_trace(struct task_struct *task, unsigned long *sp)
404 {
405 unsigned long a0, a1, pc;
406 unsigned long sp_start, sp_end;
407
408 if (sp)
409 a1 = (unsigned long)sp;
410 else
411 a1 = (unsigned long)stack_pointer(task);
412
413 sp_start = a1 & ~(THREAD_SIZE-1);
414 sp_end = sp_start + THREAD_SIZE;
415
416 printk("Call Trace:");
417 #ifdef CONFIG_KALLSYMS
418 printk("\n");
419 #endif
420 spill_registers();
421
422 while (a1 > sp_start && a1 < sp_end) {
423 sp = (unsigned long*)a1;
424
425 a0 = *(sp - 4);
426 a1 = *(sp - 3);
427
428 if (a1 <= (unsigned long) sp)
429 break;
430
431 pc = MAKE_PC_FROM_RA(a0, a1);
432
433 if (kernel_text_address(pc)) {
434 printk(" [<%08lx>] ", pc);
435 print_symbol("%s\n", pc);
436 }
437 }
438 printk("\n");
439 }
440
441 /*
442 * This routine abuses get_user()/put_user() to reference pointers
443 * with at least a bit of error checking ...
444 */
445
446 static int kstack_depth_to_print = 24;
447
show_stack(struct task_struct * task,unsigned long * sp)448 void show_stack(struct task_struct *task, unsigned long *sp)
449 {
450 int i = 0;
451 unsigned long *stack;
452
453 if (!sp)
454 sp = stack_pointer(task);
455 stack = sp;
456
457 printk("\nStack: ");
458
459 for (i = 0; i < kstack_depth_to_print; i++) {
460 if (kstack_end(sp))
461 break;
462 if (i && ((i % 8) == 0))
463 printk("\n ");
464 printk("%08lx ", *sp++);
465 }
466 printk("\n");
467 show_trace(task, stack);
468 }
469
dump_stack(void)470 void dump_stack(void)
471 {
472 show_stack(current, NULL);
473 }
474
475 EXPORT_SYMBOL(dump_stack);
476
477
show_code(unsigned int * pc)478 void show_code(unsigned int *pc)
479 {
480 long i;
481
482 printk("\nCode:");
483
484 for(i = -3 ; i < 6 ; i++) {
485 unsigned long insn;
486 if (__get_user(insn, pc + i)) {
487 printk(" (Bad address in pc)\n");
488 break;
489 }
490 printk("%c%08lx%c",(i?' ':'<'),insn,(i?' ':'>'));
491 }
492 }
493
494 DEFINE_SPINLOCK(die_lock);
495
die(const char * str,struct pt_regs * regs,long err)496 void die(const char * str, struct pt_regs * regs, long err)
497 {
498 static int die_counter;
499 int nl = 0;
500
501 console_verbose();
502 spin_lock_irq(&die_lock);
503
504 printk("%s: sig: %ld [#%d]\n", str, err, ++die_counter);
505 #ifdef CONFIG_PREEMPT
506 printk("PREEMPT ");
507 nl = 1;
508 #endif
509 if (nl)
510 printk("\n");
511 show_regs(regs);
512 if (!user_mode(regs))
513 show_stack(NULL, (unsigned long*)regs->areg[1]);
514
515 add_taint(TAINT_DIE);
516 spin_unlock_irq(&die_lock);
517
518 if (in_interrupt())
519 panic("Fatal exception in interrupt");
520
521 if (panic_on_oops)
522 panic("Fatal exception");
523
524 do_exit(err);
525 }
526
527
528