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