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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/signal.h>
 28 #include <linux/sched/debug.h>
 29 #include <linux/sched/task_stack.h>
 30 #include <linux/init.h>
 31 #include <linux/module.h>
 32 #include <linux/stringify.h>
 33 #include <linux/kallsyms.h>
 34 #include <linux/delay.h>
 35 #include <linux/hardirq.h>
 36 #include <linux/ratelimit.h>
 37 
 38 #include <asm/stacktrace.h>
 39 #include <asm/ptrace.h>
 40 #include <asm/timex.h>
 41 #include <linux/uaccess.h>
 42 #include <asm/pgtable.h>
 43 #include <asm/processor.h>
 44 #include <asm/traps.h>
 45 #include <asm/hw_breakpoint.h>
 46 
 47 /*
 48  * Machine specific interrupt handlers
 49  */
 50 
 51 extern void kernel_exception(void);
 52 extern void user_exception(void);
 53 
 54 extern void fast_illegal_instruction_user(void);
 55 extern void fast_syscall_user(void);
 56 extern void fast_alloca(void);
 57 extern void fast_unaligned(void);
 58 extern void fast_second_level_miss(void);
 59 extern void fast_store_prohibited(void);
 60 extern void fast_coprocessor(void);
 61 
 62 extern void do_illegal_instruction (struct pt_regs*);
 63 extern void do_interrupt (struct pt_regs*);
 64 extern void do_nmi(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 #ifdef CONFIG_USER_ABI_CALL0_PROBE
 92 { EXCCAUSE_ILLEGAL_INSTRUCTION, USER,      fast_illegal_instruction_user },
 93 #endif
 94 { EXCCAUSE_ILLEGAL_INSTRUCTION, 0,         do_illegal_instruction},
 95 { EXCCAUSE_SYSTEM_CALL,         USER,      fast_syscall_user },
 96 { EXCCAUSE_SYSTEM_CALL,         0,         system_call },
 97 /* EXCCAUSE_INSTRUCTION_FETCH unhandled */
 98 /* EXCCAUSE_LOAD_STORE_ERROR unhandled*/
 99 { EXCCAUSE_LEVEL1_INTERRUPT,    0,         do_interrupt },
100 { EXCCAUSE_ALLOCA,              USER|KRNL, fast_alloca },
101 /* EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */
102 /* EXCCAUSE_PRIVILEGED unhandled */
103 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
104 #ifdef CONFIG_XTENSA_UNALIGNED_USER
105 { EXCCAUSE_UNALIGNED,           USER,      fast_unaligned },
106 #endif
107 { EXCCAUSE_UNALIGNED,           0,         do_unaligned_user },
108 { EXCCAUSE_UNALIGNED,           KRNL,      fast_unaligned },
109 #endif
110 #ifdef CONFIG_MMU
111 { EXCCAUSE_ITLB_MISS,           0,         do_page_fault },
112 { EXCCAUSE_ITLB_MISS,           USER|KRNL, fast_second_level_miss},
113 { EXCCAUSE_ITLB_MULTIHIT,               0,         do_multihit },
114 { EXCCAUSE_ITLB_PRIVILEGE,      0,         do_page_fault },
115 /* EXCCAUSE_SIZE_RESTRICTION unhandled */
116 { EXCCAUSE_FETCH_CACHE_ATTRIBUTE,       0,         do_page_fault },
117 { EXCCAUSE_DTLB_MISS,           USER|KRNL, fast_second_level_miss},
118 { EXCCAUSE_DTLB_MISS,           0,         do_page_fault },
119 { EXCCAUSE_DTLB_MULTIHIT,               0,         do_multihit },
120 { EXCCAUSE_DTLB_PRIVILEGE,      0,         do_page_fault },
121 /* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */
122 { EXCCAUSE_STORE_CACHE_ATTRIBUTE,       USER|KRNL, fast_store_prohibited },
123 { EXCCAUSE_STORE_CACHE_ATTRIBUTE,       0,         do_page_fault },
124 { EXCCAUSE_LOAD_CACHE_ATTRIBUTE,        0,         do_page_fault },
125 #endif /* CONFIG_MMU */
126 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */
127 #if XTENSA_HAVE_COPROCESSOR(0)
128 COPROCESSOR(0),
129 #endif
130 #if XTENSA_HAVE_COPROCESSOR(1)
131 COPROCESSOR(1),
132 #endif
133 #if XTENSA_HAVE_COPROCESSOR(2)
134 COPROCESSOR(2),
135 #endif
136 #if XTENSA_HAVE_COPROCESSOR(3)
137 COPROCESSOR(3),
138 #endif
139 #if XTENSA_HAVE_COPROCESSOR(4)
140 COPROCESSOR(4),
141 #endif
142 #if XTENSA_HAVE_COPROCESSOR(5)
143 COPROCESSOR(5),
144 #endif
145 #if XTENSA_HAVE_COPROCESSOR(6)
146 COPROCESSOR(6),
147 #endif
148 #if XTENSA_HAVE_COPROCESSOR(7)
149 COPROCESSOR(7),
150 #endif
151 #if XTENSA_FAKE_NMI
152 { EXCCAUSE_MAPPED_NMI,                  0,              do_nmi },
153 #endif
154 { EXCCAUSE_MAPPED_DEBUG,                0,              do_debug },
155 { -1, -1, 0 }
156 
157 };
158 
159 /* The exception table <exc_table> serves two functions:
160  * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c)
161  * 2. it is a temporary memory buffer for the exception handlers.
162  */
163 
164 DEFINE_PER_CPU(struct exc_table, exc_table);
165 DEFINE_PER_CPU(struct debug_table, debug_table);
166 
167 void die(const char*, struct pt_regs*, long);
168 
169 static inline void
170 __die_if_kernel(const char *str, struct pt_regs *regs, long err)
171 {
172         if (!user_mode(regs))
173                 die(str, regs, err);
174 }
175 
176 /*
177  * Unhandled Exceptions. Kill user task or panic if in kernel space.
178  */
179 
180 void do_unhandled(struct pt_regs *regs, unsigned long exccause)
181 {
182         __die_if_kernel("Caught unhandled exception - should not happen",
183                         regs, SIGKILL);
184 
185         /* If in user mode, send SIGILL signal to current process */
186         pr_info_ratelimited("Caught unhandled exception in '%s' "
187                             "(pid = %d, pc = %#010lx) - should not happen\n"
188                             "\tEXCCAUSE is %ld\n",
189                             current->comm, task_pid_nr(current), regs->pc,
190                             exccause);
191         force_sig(SIGILL);
192 }
193 
194 /*
195  * Multi-hit exception. This if fatal!
196  */
197 
198 void do_multihit(struct pt_regs *regs, unsigned long exccause)
199 {
200         die("Caught multihit exception", regs, SIGKILL);
201 }
202 
203 /*
204  * IRQ handler.
205  */
206 
207 extern void do_IRQ(int, struct pt_regs *);
208 
209 #if XTENSA_FAKE_NMI
210 
211 #define IS_POW2(v) (((v) & ((v) - 1)) == 0)
212 
213 #if !(PROFILING_INTLEVEL == XCHAL_EXCM_LEVEL && \
214       IS_POW2(XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL)))
215 #warning "Fake NMI is requested for PMM, but there are other IRQs at or above its level."
216 #warning "Fake NMI will be used, but there will be a bugcheck if one of those IRQs fire."
217 
218 static inline void check_valid_nmi(void)
219 {
220         unsigned intread = xtensa_get_sr(interrupt);
221         unsigned intenable = xtensa_get_sr(intenable);
222 
223         BUG_ON(intread & intenable &
224                ~(XTENSA_INTLEVEL_ANDBELOW_MASK(PROFILING_INTLEVEL) ^
225                  XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL) ^
226                  BIT(XCHAL_PROFILING_INTERRUPT)));
227 }
228 
229 #else
230 
231 static inline void check_valid_nmi(void)
232 {
233 }
234 
235 #endif
236 
237 irqreturn_t xtensa_pmu_irq_handler(int irq, void *dev_id);
238 
239 DEFINE_PER_CPU(unsigned long, nmi_count);
240 
241 void do_nmi(struct pt_regs *regs)
242 {
243         struct pt_regs *old_regs;
244 
245         if ((regs->ps & PS_INTLEVEL_MASK) < LOCKLEVEL)
246                 trace_hardirqs_off();
247 
248         old_regs = set_irq_regs(regs);
249         nmi_enter();
250         ++*this_cpu_ptr(&nmi_count);
251         check_valid_nmi();
252         xtensa_pmu_irq_handler(0, NULL);
253         nmi_exit();
254         set_irq_regs(old_regs);
255 }
256 #endif
257 
258 void do_interrupt(struct pt_regs *regs)
259 {
260         static const unsigned int_level_mask[] = {
261                 0,
262                 XCHAL_INTLEVEL1_MASK,
263                 XCHAL_INTLEVEL2_MASK,
264                 XCHAL_INTLEVEL3_MASK,
265                 XCHAL_INTLEVEL4_MASK,
266                 XCHAL_INTLEVEL5_MASK,
267                 XCHAL_INTLEVEL6_MASK,
268                 XCHAL_INTLEVEL7_MASK,
269         };
270         struct pt_regs *old_regs;
271 
272         trace_hardirqs_off();
273 
274         old_regs = set_irq_regs(regs);
275         irq_enter();
276 
277         for (;;) {
278                 unsigned intread = xtensa_get_sr(interrupt);
279                 unsigned intenable = xtensa_get_sr(intenable);
280                 unsigned int_at_level = intread & intenable;
281                 unsigned level;
282 
283                 for (level = LOCKLEVEL; level > 0; --level) {
284                         if (int_at_level & int_level_mask[level]) {
285                                 int_at_level &= int_level_mask[level];
286                                 break;
287                         }
288                 }
289 
290                 if (level == 0)
291                         break;
292 
293                 do_IRQ(__ffs(int_at_level), regs);
294         }
295 
296         irq_exit();
297         set_irq_regs(old_regs);
298 }
299 
300 /*
301  * Illegal instruction. Fatal if in kernel space.
302  */
303 
304 void
305 do_illegal_instruction(struct pt_regs *regs)
306 {
307         __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);
308 
309         /* If in user mode, send SIGILL signal to current process. */
310 
311         pr_info_ratelimited("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n",
312                             current->comm, task_pid_nr(current), regs->pc);
313         force_sig(SIGILL);
314 }
315 
316 
317 /*
318  * Handle unaligned memory accesses from user space. Kill task.
319  *
320  * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory
321  * accesses causes from user space.
322  */
323 
324 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
325 void
326 do_unaligned_user (struct pt_regs *regs)
327 {
328         __die_if_kernel("Unhandled unaligned exception in kernel",
329                         regs, SIGKILL);
330 
331         current->thread.bad_vaddr = regs->excvaddr;
332         current->thread.error_code = -3;
333         pr_info_ratelimited("Unaligned memory access to %08lx in '%s' "
334                             "(pid = %d, pc = %#010lx)\n",
335                             regs->excvaddr, current->comm,
336                             task_pid_nr(current), regs->pc);
337         force_sig_fault(SIGBUS, BUS_ADRALN, (void *) regs->excvaddr);
338 }
339 #endif
340 
341 /* Handle debug events.
342  * When CONFIG_HAVE_HW_BREAKPOINT is on this handler is called with
343  * preemption disabled to avoid rescheduling and keep mapping of hardware
344  * breakpoint structures to debug registers intact, so that
345  * DEBUGCAUSE.DBNUM could be used in case of data breakpoint hit.
346  */
347 void
348 do_debug(struct pt_regs *regs)
349 {
350 #ifdef CONFIG_HAVE_HW_BREAKPOINT
351         int ret = check_hw_breakpoint(regs);
352 
353         preempt_enable();
354         if (ret == 0)
355                 return;
356 #endif
357         __die_if_kernel("Breakpoint in kernel", regs, SIGKILL);
358 
359         /* If in user mode, send SIGTRAP signal to current process */
360 
361         force_sig(SIGTRAP);
362 }
363 
364 
365 #define set_handler(type, cause, handler)                               \
366         do {                                                            \
367                 unsigned int cpu;                                       \
368                                                                         \
369                 for_each_possible_cpu(cpu)                              \
370                         per_cpu(exc_table, cpu).type[cause] = (handler);\
371         } while (0)
372 
373 /* Set exception C handler - for temporary use when probing exceptions */
374 
375 void * __init trap_set_handler(int cause, void *handler)
376 {
377         void *previous = per_cpu(exc_table, 0).default_handler[cause];
378 
379         set_handler(default_handler, cause, handler);
380         return previous;
381 }
382 
383 
384 static void trap_init_excsave(void)
385 {
386         unsigned long excsave1 = (unsigned long)this_cpu_ptr(&exc_table);
387         __asm__ __volatile__("wsr  %0, excsave1\n" : : "a" (excsave1));
388 }
389 
390 static void trap_init_debug(void)
391 {
392         unsigned long debugsave = (unsigned long)this_cpu_ptr(&debug_table);
393 
394         this_cpu_ptr(&debug_table)->debug_exception = debug_exception;
395         __asm__ __volatile__("wsr %0, excsave" __stringify(XCHAL_DEBUGLEVEL)
396                              :: "a"(debugsave));
397 }
398 
399 /*
400  * Initialize dispatch tables.
401  *
402  * The exception vectors are stored compressed the __init section in the
403  * dispatch_init_table. This function initializes the following three tables
404  * from that compressed table:
405  * - fast user          first dispatch table for user exceptions
406  * - fast kernel        first dispatch table for kernel exceptions
407  * - default C-handler  C-handler called by the default fast handler.
408  *
409  * See vectors.S for more details.
410  */
411 
412 void __init trap_init(void)
413 {
414         int i;
415 
416         /* Setup default vectors. */
417 
418         for (i = 0; i < EXCCAUSE_N; i++) {
419                 set_handler(fast_user_handler, i, user_exception);
420                 set_handler(fast_kernel_handler, i, kernel_exception);
421                 set_handler(default_handler, i, do_unhandled);
422         }
423 
424         /* Setup specific handlers. */
425 
426         for(i = 0; dispatch_init_table[i].cause >= 0; i++) {
427                 int fast = dispatch_init_table[i].fast;
428                 int cause = dispatch_init_table[i].cause;
429                 void *handler = dispatch_init_table[i].handler;
430 
431                 if (fast == 0)
432                         set_handler(default_handler, cause, handler);
433                 if ((fast & USER) != 0)
434                         set_handler(fast_user_handler, cause, handler);
435                 if ((fast & KRNL) != 0)
436                         set_handler(fast_kernel_handler, cause, handler);
437         }
438 
439         /* Initialize EXCSAVE_1 to hold the address of the exception table. */
440         trap_init_excsave();
441         trap_init_debug();
442 }
443 
444 #ifdef CONFIG_SMP
445 void secondary_trap_init(void)
446 {
447         trap_init_excsave();
448         trap_init_debug();
449 }
450 #endif
451 
452 /*
453  * This function dumps the current valid window frame and other base registers.
454  */
455 
456 void show_regs(struct pt_regs * regs)
457 {
458         int i, wmask;
459 
460         show_regs_print_info(KERN_DEFAULT);
461 
462         wmask = regs->wmask & ~1;
463 
464         for (i = 0; i < 16; i++) {
465                 if ((i % 8) == 0)
466                         pr_info("a%02d:", i);
467                 pr_cont(" %08lx", regs->areg[i]);
468         }
469         pr_cont("\n");
470         pr_info("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n",
471                 regs->pc, regs->ps, regs->depc, regs->excvaddr);
472         pr_info("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n",
473                 regs->lbeg, regs->lend, regs->lcount, regs->sar);
474         if (user_mode(regs))
475                 pr_cont("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n",
476                         regs->windowbase, regs->windowstart, regs->wmask,
477                         regs->syscall);
478 }
479 
480 static int show_trace_cb(struct stackframe *frame, void *data)
481 {
482         if (kernel_text_address(frame->pc))
483                 pr_cont(" [<%08lx>] %pB\n", frame->pc, (void *)frame->pc);
484         return 0;
485 }
486 
487 void show_trace(struct task_struct *task, unsigned long *sp)
488 {
489         if (!sp)
490                 sp = stack_pointer(task);
491 
492         pr_info("Call Trace:\n");
493         walk_stackframe(sp, show_trace_cb, NULL);
494 }
495 
496 #define STACK_DUMP_ENTRY_SIZE 4
497 #define STACK_DUMP_LINE_SIZE 32
498 static size_t kstack_depth_to_print = CONFIG_PRINT_STACK_DEPTH;
499 
500 void show_stack(struct task_struct *task, unsigned long *sp)
501 {
502         size_t len;
503 
504         if (!sp)
505                 sp = stack_pointer(task);
506 
507         len = min((-(size_t)sp) & (THREAD_SIZE - STACK_DUMP_ENTRY_SIZE),
508                   kstack_depth_to_print * STACK_DUMP_ENTRY_SIZE);
509 
510         pr_info("Stack:\n");
511         print_hex_dump(KERN_INFO, " ", DUMP_PREFIX_NONE,
512                        STACK_DUMP_LINE_SIZE, STACK_DUMP_ENTRY_SIZE,
513                        sp, len, false);
514         show_trace(task, sp);
515 }
516 
517 DEFINE_SPINLOCK(die_lock);
518 
519 void die(const char * str, struct pt_regs * regs, long err)
520 {
521         static int die_counter;
522         const char *pr = "";
523 
524         if (IS_ENABLED(CONFIG_PREEMPTION))
525                 pr = IS_ENABLED(CONFIG_PREEMPT_RT) ? " PREEMPT_RT" : " PREEMPT";
526 
527         console_verbose();
528         spin_lock_irq(&die_lock);
529 
530         pr_info("%s: sig: %ld [#%d]%s\n", str, err, ++die_counter, pr);
531         show_regs(regs);
532         if (!user_mode(regs))
533                 show_stack(NULL, (unsigned long*)regs->areg[1]);
534 
535         add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
536         spin_unlock_irq(&die_lock);
537 
538         if (in_interrupt())
539                 panic("Fatal exception in interrupt");
540 
541         if (panic_on_oops)
542                 panic("Fatal exception");
543 
544         do_exit(err);
545 }
546 

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