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Linux/arch/xtensa/kernel/traps.c

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  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_unaligned_user (struct pt_regs*);
 66 extern void do_multihit (struct pt_regs*, unsigned long);
 67 extern void do_page_fault (struct pt_regs*, unsigned long);
 68 extern void do_debug (struct pt_regs*);
 69 extern void system_call (struct pt_regs*);
 70 
 71 /*
 72  * The vector table must be preceded by a save area (which
 73  * implies it must be in RAM, unless one places RAM immediately
 74  * before a ROM and puts the vector at the start of the ROM (!))
 75  */
 76 
 77 #define KRNL            0x01
 78 #define USER            0x02
 79 
 80 #define COPROCESSOR(x)                                                  \
 81 { EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER, fast_coprocessor }
 82 
 83 typedef struct {
 84         int cause;
 85         int fast;
 86         void* handler;
 87 } dispatch_init_table_t;
 88 
 89 static dispatch_init_table_t __initdata dispatch_init_table[] = {
 90 
 91 { EXCCAUSE_ILLEGAL_INSTRUCTION, 0,         do_illegal_instruction},
 92 { EXCCAUSE_SYSTEM_CALL,         KRNL,      fast_syscall_kernel },
 93 { EXCCAUSE_SYSTEM_CALL,         USER,      fast_syscall_user },
 94 { EXCCAUSE_SYSTEM_CALL,         0,         system_call },
 95 /* EXCCAUSE_INSTRUCTION_FETCH unhandled */
 96 /* EXCCAUSE_LOAD_STORE_ERROR unhandled*/
 97 { EXCCAUSE_LEVEL1_INTERRUPT,    0,         do_interrupt },
 98 { EXCCAUSE_ALLOCA,              USER|KRNL, fast_alloca },
 99 /* EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */
100 /* EXCCAUSE_PRIVILEGED unhandled */
101 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
102 #ifdef CONFIG_XTENSA_UNALIGNED_USER
103 { EXCCAUSE_UNALIGNED,           USER,      fast_unaligned },
104 #endif
105 { EXCCAUSE_UNALIGNED,           0,         do_unaligned_user },
106 { EXCCAUSE_UNALIGNED,           KRNL,      fast_unaligned },
107 #endif
108 #ifdef CONFIG_MMU
109 { EXCCAUSE_ITLB_MISS,           0,         do_page_fault },
110 { EXCCAUSE_ITLB_MISS,           USER|KRNL, fast_second_level_miss},
111 { EXCCAUSE_ITLB_MULTIHIT,               0,         do_multihit },
112 { EXCCAUSE_ITLB_PRIVILEGE,      0,         do_page_fault },
113 /* EXCCAUSE_SIZE_RESTRICTION unhandled */
114 { EXCCAUSE_FETCH_CACHE_ATTRIBUTE,       0,         do_page_fault },
115 { EXCCAUSE_DTLB_MISS,           USER|KRNL, fast_second_level_miss},
116 { EXCCAUSE_DTLB_MISS,           0,         do_page_fault },
117 { EXCCAUSE_DTLB_MULTIHIT,               0,         do_multihit },
118 { EXCCAUSE_DTLB_PRIVILEGE,      0,         do_page_fault },
119 /* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */
120 { EXCCAUSE_STORE_CACHE_ATTRIBUTE,       USER|KRNL, fast_store_prohibited },
121 { EXCCAUSE_STORE_CACHE_ATTRIBUTE,       0,         do_page_fault },
122 { EXCCAUSE_LOAD_CACHE_ATTRIBUTE,        0,         do_page_fault },
123 #endif /* CONFIG_MMU */
124 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */
125 #if XTENSA_HAVE_COPROCESSOR(0)
126 COPROCESSOR(0),
127 #endif
128 #if XTENSA_HAVE_COPROCESSOR(1)
129 COPROCESSOR(1),
130 #endif
131 #if XTENSA_HAVE_COPROCESSOR(2)
132 COPROCESSOR(2),
133 #endif
134 #if XTENSA_HAVE_COPROCESSOR(3)
135 COPROCESSOR(3),
136 #endif
137 #if XTENSA_HAVE_COPROCESSOR(4)
138 COPROCESSOR(4),
139 #endif
140 #if XTENSA_HAVE_COPROCESSOR(5)
141 COPROCESSOR(5),
142 #endif
143 #if XTENSA_HAVE_COPROCESSOR(6)
144 COPROCESSOR(6),
145 #endif
146 #if XTENSA_HAVE_COPROCESSOR(7)
147 COPROCESSOR(7),
148 #endif
149 { EXCCAUSE_MAPPED_DEBUG,                0,              do_debug },
150 { -1, -1, 0 }
151 
152 };
153 
154 /* The exception table <exc_table> serves two functions:
155  * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c)
156  * 2. it is a temporary memory buffer for the exception handlers.
157  */
158 
159 DEFINE_PER_CPU(unsigned long, exc_table[EXC_TABLE_SIZE/4]);
160 
161 void die(const char*, struct pt_regs*, long);
162 
163 static inline void
164 __die_if_kernel(const char *str, struct pt_regs *regs, long err)
165 {
166         if (!user_mode(regs))
167                 die(str, regs, err);
168 }
169 
170 /*
171  * Unhandled Exceptions. Kill user task or panic if in kernel space.
172  */
173 
174 void do_unhandled(struct pt_regs *regs, unsigned long exccause)
175 {
176         __die_if_kernel("Caught unhandled exception - should not happen",
177                         regs, SIGKILL);
178 
179         /* If in user mode, send SIGILL signal to current process */
180         printk("Caught unhandled exception in '%s' "
181                "(pid = %d, pc = %#010lx) - should not happen\n"
182                "\tEXCCAUSE is %ld\n",
183                current->comm, task_pid_nr(current), regs->pc, exccause);
184         force_sig(SIGILL, current);
185 }
186 
187 /*
188  * Multi-hit exception. This if fatal!
189  */
190 
191 void do_multihit(struct pt_regs *regs, unsigned long exccause)
192 {
193         die("Caught multihit exception", regs, SIGKILL);
194 }
195 
196 /*
197  * IRQ handler.
198  */
199 
200 extern void do_IRQ(int, struct pt_regs *);
201 
202 void do_interrupt(struct pt_regs *regs)
203 {
204         static const unsigned int_level_mask[] = {
205                 0,
206                 XCHAL_INTLEVEL1_MASK,
207                 XCHAL_INTLEVEL2_MASK,
208                 XCHAL_INTLEVEL3_MASK,
209                 XCHAL_INTLEVEL4_MASK,
210                 XCHAL_INTLEVEL5_MASK,
211                 XCHAL_INTLEVEL6_MASK,
212                 XCHAL_INTLEVEL7_MASK,
213         };
214         struct pt_regs *old_regs = set_irq_regs(regs);
215 
216         irq_enter();
217 
218         for (;;) {
219                 unsigned intread = get_sr(interrupt);
220                 unsigned intenable = get_sr(intenable);
221                 unsigned int_at_level = intread & intenable;
222                 unsigned level;
223 
224                 for (level = LOCKLEVEL; level > 0; --level) {
225                         if (int_at_level & int_level_mask[level]) {
226                                 int_at_level &= int_level_mask[level];
227                                 break;
228                         }
229                 }
230 
231                 if (level == 0)
232                         break;
233 
234                 do_IRQ(__ffs(int_at_level), regs);
235         }
236 
237         irq_exit();
238         set_irq_regs(old_regs);
239 }
240 
241 /*
242  * Illegal instruction. Fatal if in kernel space.
243  */
244 
245 void
246 do_illegal_instruction(struct pt_regs *regs)
247 {
248         __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);
249 
250         /* If in user mode, send SIGILL signal to current process. */
251 
252         printk("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n",
253             current->comm, task_pid_nr(current), regs->pc);
254         force_sig(SIGILL, current);
255 }
256 
257 
258 /*
259  * Handle unaligned memory accesses from user space. Kill task.
260  *
261  * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory
262  * accesses causes from user space.
263  */
264 
265 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
266 void
267 do_unaligned_user (struct pt_regs *regs)
268 {
269         siginfo_t info;
270 
271         __die_if_kernel("Unhandled unaligned exception in kernel",
272                         regs, SIGKILL);
273 
274         current->thread.bad_vaddr = regs->excvaddr;
275         current->thread.error_code = -3;
276         printk("Unaligned memory access to %08lx in '%s' "
277                "(pid = %d, pc = %#010lx)\n",
278                regs->excvaddr, current->comm, task_pid_nr(current), regs->pc);
279         info.si_signo = SIGBUS;
280         info.si_errno = 0;
281         info.si_code = BUS_ADRALN;
282         info.si_addr = (void *) regs->excvaddr;
283         force_sig_info(SIGSEGV, &info, current);
284 
285 }
286 #endif
287 
288 void
289 do_debug(struct pt_regs *regs)
290 {
291 #ifdef CONFIG_KGDB
292         /* If remote debugging is configured AND enabled, we give control to
293          * kgdb.  Otherwise, we fall through, perhaps giving control to the
294          * native debugger.
295          */
296 
297         if (gdb_enter) {
298                 extern void gdb_handle_exception(struct pt_regs *);
299                 gdb_handle_exception(regs);
300                 return_from_debug_flag = 1;
301                 return;
302         }
303 #endif
304 
305         __die_if_kernel("Breakpoint in kernel", regs, SIGKILL);
306 
307         /* If in user mode, send SIGTRAP signal to current process */
308 
309         force_sig(SIGTRAP, current);
310 }
311 
312 
313 static void set_handler(int idx, void *handler)
314 {
315         unsigned int cpu;
316 
317         for_each_possible_cpu(cpu)
318                 per_cpu(exc_table, cpu)[idx] = (unsigned long)handler;
319 }
320 
321 /* Set exception C handler - for temporary use when probing exceptions */
322 
323 void * __init trap_set_handler(int cause, void *handler)
324 {
325         void *previous = (void *)per_cpu(exc_table, 0)[
326                 EXC_TABLE_DEFAULT / 4 + cause];
327         set_handler(EXC_TABLE_DEFAULT / 4 + cause, handler);
328         return previous;
329 }
330 
331 
332 static void trap_init_excsave(void)
333 {
334         unsigned long excsave1 = (unsigned long)this_cpu_ptr(exc_table);
335         __asm__ __volatile__("wsr  %0, excsave1\n" : : "a" (excsave1));
336 }
337 
338 /*
339  * Initialize dispatch tables.
340  *
341  * The exception vectors are stored compressed the __init section in the
342  * dispatch_init_table. This function initializes the following three tables
343  * from that compressed table:
344  * - fast user          first dispatch table for user exceptions
345  * - fast kernel        first dispatch table for kernel exceptions
346  * - default C-handler  C-handler called by the default fast handler.
347  *
348  * See vectors.S for more details.
349  */
350 
351 void __init trap_init(void)
352 {
353         int i;
354 
355         /* Setup default vectors. */
356 
357         for(i = 0; i < 64; i++) {
358                 set_handler(EXC_TABLE_FAST_USER/4   + i, user_exception);
359                 set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception);
360                 set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled);
361         }
362 
363         /* Setup specific handlers. */
364 
365         for(i = 0; dispatch_init_table[i].cause >= 0; i++) {
366 
367                 int fast = dispatch_init_table[i].fast;
368                 int cause = dispatch_init_table[i].cause;
369                 void *handler = dispatch_init_table[i].handler;
370 
371                 if (fast == 0)
372                         set_handler (EXC_TABLE_DEFAULT/4 + cause, handler);
373                 if (fast && fast & USER)
374                         set_handler (EXC_TABLE_FAST_USER/4 + cause, handler);
375                 if (fast && fast & KRNL)
376                         set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler);
377         }
378 
379         /* Initialize EXCSAVE_1 to hold the address of the exception table. */
380         trap_init_excsave();
381 }
382 
383 #ifdef CONFIG_SMP
384 void secondary_trap_init(void)
385 {
386         trap_init_excsave();
387 }
388 #endif
389 
390 /*
391  * This function dumps the current valid window frame and other base registers.
392  */
393 
394 void show_regs(struct pt_regs * regs)
395 {
396         int i, wmask;
397 
398         show_regs_print_info(KERN_DEFAULT);
399 
400         wmask = regs->wmask & ~1;
401 
402         for (i = 0; i < 16; i++) {
403                 if ((i % 8) == 0)
404                         printk(KERN_INFO "a%02d:", i);
405                 printk(KERN_CONT " %08lx", regs->areg[i]);
406         }
407         printk(KERN_CONT "\n");
408 
409         printk("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n",
410                regs->pc, regs->ps, regs->depc, regs->excvaddr);
411         printk("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n",
412                regs->lbeg, regs->lend, regs->lcount, regs->sar);
413         if (user_mode(regs))
414                 printk("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n",
415                        regs->windowbase, regs->windowstart, regs->wmask,
416                        regs->syscall);
417 }
418 
419 static int show_trace_cb(struct stackframe *frame, void *data)
420 {
421         if (kernel_text_address(frame->pc)) {
422                 printk(" [<%08lx>] ", frame->pc);
423                 print_symbol("%s\n", frame->pc);
424         }
425         return 0;
426 }
427 
428 void show_trace(struct task_struct *task, unsigned long *sp)
429 {
430         if (!sp)
431                 sp = stack_pointer(task);
432 
433         printk("Call Trace:");
434 #ifdef CONFIG_KALLSYMS
435         printk("\n");
436 #endif
437         walk_stackframe(sp, show_trace_cb, NULL);
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 
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 
470 void show_code(unsigned int *pc)
471 {
472         long i;
473 
474         printk("\nCode:");
475 
476         for(i = -3 ; i < 6 ; i++) {
477                 unsigned long insn;
478                 if (__get_user(insn, pc + i)) {
479                         printk(" (Bad address in pc)\n");
480                         break;
481                 }
482                 printk("%c%08lx%c",(i?' ':'<'),insn,(i?' ':'>'));
483         }
484 }
485 
486 DEFINE_SPINLOCK(die_lock);
487 
488 void die(const char * str, struct pt_regs * regs, long err)
489 {
490         static int die_counter;
491         int nl = 0;
492 
493         console_verbose();
494         spin_lock_irq(&die_lock);
495 
496         printk("%s: sig: %ld [#%d]\n", str, err, ++die_counter);
497 #ifdef CONFIG_PREEMPT
498         printk("PREEMPT ");
499         nl = 1;
500 #endif
501         if (nl)
502                 printk("\n");
503         show_regs(regs);
504         if (!user_mode(regs))
505                 show_stack(NULL, (unsigned long*)regs->areg[1]);
506 
507         add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
508         spin_unlock_irq(&die_lock);
509 
510         if (in_interrupt())
511                 panic("Fatal exception in interrupt");
512 
513         if (panic_on_oops)
514                 panic("Fatal exception");
515 
516         do_exit(err);
517 }
518 

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