xref: /openbmc/linux/arch/xtensa/kernel/traps.c (revision 1c4087e9)
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/cpu.h>
27 #include <linux/kernel.h>
28 #include <linux/sched/signal.h>
29 #include <linux/sched/debug.h>
30 #include <linux/sched/task_stack.h>
31 #include <linux/init.h>
32 #include <linux/module.h>
33 #include <linux/stringify.h>
34 #include <linux/kallsyms.h>
35 #include <linux/delay.h>
36 #include <linux/hardirq.h>
37 #include <linux/ratelimit.h>
38 #include <linux/pgtable.h>
39 
40 #include <asm/stacktrace.h>
41 #include <asm/ptrace.h>
42 #include <asm/timex.h>
43 #include <linux/uaccess.h>
44 #include <asm/processor.h>
45 #include <asm/traps.h>
46 #include <asm/hw_breakpoint.h>
47 
48 /*
49  * Machine specific interrupt handlers
50  */
51 
52 static void do_illegal_instruction(struct pt_regs *regs);
53 static void do_div0(struct pt_regs *regs);
54 static void do_interrupt(struct pt_regs *regs);
55 #if XTENSA_FAKE_NMI
56 static void do_nmi(struct pt_regs *regs);
57 #endif
58 #ifdef CONFIG_XTENSA_LOAD_STORE
59 static void do_load_store(struct pt_regs *regs);
60 #endif
61 static void do_unaligned_user(struct pt_regs *regs);
62 static void do_multihit(struct pt_regs *regs);
63 #if XTENSA_HAVE_COPROCESSORS
64 static void do_coprocessor(struct pt_regs *regs);
65 #endif
66 static void do_debug(struct pt_regs *regs);
67 
68 /*
69  * The vector table must be preceded by a save area (which
70  * implies it must be in RAM, unless one places RAM immediately
71  * before a ROM and puts the vector at the start of the ROM (!))
72  */
73 
74 #define KRNL		0x01
75 #define USER		0x02
76 
77 #define COPROCESSOR(x)							\
78 { EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER|KRNL, fast_coprocessor },\
79 { EXCCAUSE_COPROCESSOR ## x ## _DISABLED, 0, do_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 #ifdef CONFIG_USER_ABI_CALL0_PROBE
90 { EXCCAUSE_ILLEGAL_INSTRUCTION,	USER,	   fast_illegal_instruction_user },
91 #endif
92 { EXCCAUSE_ILLEGAL_INSTRUCTION,	0,	   do_illegal_instruction},
93 { EXCCAUSE_SYSTEM_CALL,		USER,	   fast_syscall_user },
94 { EXCCAUSE_SYSTEM_CALL,		0,	   system_call },
95 /* EXCCAUSE_INSTRUCTION_FETCH unhandled */
96 #ifdef CONFIG_XTENSA_LOAD_STORE
97 { EXCCAUSE_LOAD_STORE_ERROR,	USER|KRNL, fast_load_store },
98 { EXCCAUSE_LOAD_STORE_ERROR,	0,	   do_load_store },
99 #endif
100 { EXCCAUSE_LEVEL1_INTERRUPT,	0,	   do_interrupt },
101 #ifdef SUPPORT_WINDOWED
102 { EXCCAUSE_ALLOCA,		USER|KRNL, fast_alloca },
103 #endif
104 { EXCCAUSE_INTEGER_DIVIDE_BY_ZERO, 0,	   do_div0 },
105 /* EXCCAUSE_PRIVILEGED unhandled */
106 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION || \
107 		IS_ENABLED(CONFIG_XTENSA_LOAD_STORE)
108 #ifdef CONFIG_XTENSA_UNALIGNED_USER
109 { EXCCAUSE_UNALIGNED,		USER,	   fast_unaligned },
110 #endif
111 { EXCCAUSE_UNALIGNED,		KRNL,	   fast_unaligned },
112 #endif
113 { EXCCAUSE_UNALIGNED,		0,	   do_unaligned_user },
114 #ifdef CONFIG_MMU
115 { EXCCAUSE_ITLB_MISS,			0,	   do_page_fault },
116 { EXCCAUSE_ITLB_MISS,			USER|KRNL, fast_second_level_miss},
117 { EXCCAUSE_DTLB_MISS,			USER|KRNL, fast_second_level_miss},
118 { EXCCAUSE_DTLB_MISS,			0,	   do_page_fault },
119 { EXCCAUSE_STORE_CACHE_ATTRIBUTE,	USER|KRNL, fast_store_prohibited },
120 #endif /* CONFIG_MMU */
121 #ifdef CONFIG_PFAULT
122 { EXCCAUSE_ITLB_MULTIHIT,		0,	   do_multihit },
123 { EXCCAUSE_ITLB_PRIVILEGE,		0,	   do_page_fault },
124 { EXCCAUSE_FETCH_CACHE_ATTRIBUTE,	0,	   do_page_fault },
125 { EXCCAUSE_DTLB_MULTIHIT,		0,	   do_multihit },
126 { EXCCAUSE_DTLB_PRIVILEGE,		0,	   do_page_fault },
127 { EXCCAUSE_STORE_CACHE_ATTRIBUTE,	0,	   do_page_fault },
128 { EXCCAUSE_LOAD_CACHE_ATTRIBUTE,	0,	   do_page_fault },
129 #endif
130 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */
131 #if XTENSA_HAVE_COPROCESSOR(0)
132 COPROCESSOR(0),
133 #endif
134 #if XTENSA_HAVE_COPROCESSOR(1)
135 COPROCESSOR(1),
136 #endif
137 #if XTENSA_HAVE_COPROCESSOR(2)
138 COPROCESSOR(2),
139 #endif
140 #if XTENSA_HAVE_COPROCESSOR(3)
141 COPROCESSOR(3),
142 #endif
143 #if XTENSA_HAVE_COPROCESSOR(4)
144 COPROCESSOR(4),
145 #endif
146 #if XTENSA_HAVE_COPROCESSOR(5)
147 COPROCESSOR(5),
148 #endif
149 #if XTENSA_HAVE_COPROCESSOR(6)
150 COPROCESSOR(6),
151 #endif
152 #if XTENSA_HAVE_COPROCESSOR(7)
153 COPROCESSOR(7),
154 #endif
155 #if XTENSA_FAKE_NMI
156 { EXCCAUSE_MAPPED_NMI,			0,		do_nmi },
157 #endif
158 { EXCCAUSE_MAPPED_DEBUG,		0,		do_debug },
159 { -1, -1, 0 }
160 
161 };
162 
163 /* The exception table <exc_table> serves two functions:
164  * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c)
165  * 2. it is a temporary memory buffer for the exception handlers.
166  */
167 
168 DEFINE_PER_CPU(struct exc_table, exc_table);
169 DEFINE_PER_CPU(struct debug_table, debug_table);
170 
171 void die(const char*, struct pt_regs*, long);
172 
173 static inline void
__die_if_kernel(const char * str,struct pt_regs * regs,long err)174 __die_if_kernel(const char *str, struct pt_regs *regs, long err)
175 {
176 	if (!user_mode(regs))
177 		die(str, regs, err);
178 }
179 
180 #ifdef CONFIG_PRINT_USER_CODE_ON_UNHANDLED_EXCEPTION
dump_user_code(struct pt_regs * regs)181 static inline void dump_user_code(struct pt_regs *regs)
182 {
183 	char buf[32];
184 
185 	if (copy_from_user(buf, (void __user *)(regs->pc & -16), sizeof(buf)) == 0) {
186 		print_hex_dump(KERN_INFO, " ", DUMP_PREFIX_NONE,
187 			       32, 1, buf, sizeof(buf), false);
188 
189 	}
190 }
191 #else
dump_user_code(struct pt_regs * regs)192 static inline void dump_user_code(struct pt_regs *regs)
193 {
194 }
195 #endif
196 
197 /*
198  * Unhandled Exceptions. Kill user task or panic if in kernel space.
199  */
200 
do_unhandled(struct pt_regs * regs)201 void do_unhandled(struct pt_regs *regs)
202 {
203 	__die_if_kernel("Caught unhandled exception - should not happen",
204 			regs, SIGKILL);
205 
206 	/* If in user mode, send SIGILL signal to current process */
207 	pr_info_ratelimited("Caught unhandled exception in '%s' "
208 			    "(pid = %d, pc = %#010lx) - should not happen\n"
209 			    "\tEXCCAUSE is %ld\n",
210 			    current->comm, task_pid_nr(current), regs->pc,
211 			    regs->exccause);
212 	dump_user_code(regs);
213 	force_sig(SIGILL);
214 }
215 
216 /*
217  * Multi-hit exception. This if fatal!
218  */
219 
do_multihit(struct pt_regs * regs)220 static void do_multihit(struct pt_regs *regs)
221 {
222 	die("Caught multihit exception", regs, SIGKILL);
223 }
224 
225 /*
226  * IRQ handler.
227  */
228 
229 #if XTENSA_FAKE_NMI
230 
231 #define IS_POW2(v) (((v) & ((v) - 1)) == 0)
232 
233 #if !(PROFILING_INTLEVEL == XCHAL_EXCM_LEVEL && \
234       IS_POW2(XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL)))
235 #warning "Fake NMI is requested for PMM, but there are other IRQs at or above its level."
236 #warning "Fake NMI will be used, but there will be a bugcheck if one of those IRQs fire."
237 
check_valid_nmi(void)238 static inline void check_valid_nmi(void)
239 {
240 	unsigned intread = xtensa_get_sr(interrupt);
241 	unsigned intenable = xtensa_get_sr(intenable);
242 
243 	BUG_ON(intread & intenable &
244 	       ~(XTENSA_INTLEVEL_ANDBELOW_MASK(PROFILING_INTLEVEL) ^
245 		 XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL) ^
246 		 BIT(XCHAL_PROFILING_INTERRUPT)));
247 }
248 
249 #else
250 
check_valid_nmi(void)251 static inline void check_valid_nmi(void)
252 {
253 }
254 
255 #endif
256 
257 irqreturn_t xtensa_pmu_irq_handler(int irq, void *dev_id);
258 
259 DEFINE_PER_CPU(unsigned long, nmi_count);
260 
do_nmi(struct pt_regs * regs)261 static void do_nmi(struct pt_regs *regs)
262 {
263 	struct pt_regs *old_regs = set_irq_regs(regs);
264 
265 	nmi_enter();
266 	++*this_cpu_ptr(&nmi_count);
267 	check_valid_nmi();
268 	xtensa_pmu_irq_handler(0, NULL);
269 	nmi_exit();
270 	set_irq_regs(old_regs);
271 }
272 #endif
273 
do_interrupt(struct pt_regs * regs)274 static void do_interrupt(struct pt_regs *regs)
275 {
276 	static const unsigned int_level_mask[] = {
277 		0,
278 		XCHAL_INTLEVEL1_MASK,
279 		XCHAL_INTLEVEL2_MASK,
280 		XCHAL_INTLEVEL3_MASK,
281 		XCHAL_INTLEVEL4_MASK,
282 		XCHAL_INTLEVEL5_MASK,
283 		XCHAL_INTLEVEL6_MASK,
284 		XCHAL_INTLEVEL7_MASK,
285 	};
286 	struct pt_regs *old_regs = set_irq_regs(regs);
287 	unsigned unhandled = ~0u;
288 
289 	irq_enter();
290 
291 	for (;;) {
292 		unsigned intread = xtensa_get_sr(interrupt);
293 		unsigned intenable = xtensa_get_sr(intenable);
294 		unsigned int_at_level = intread & intenable;
295 		unsigned level;
296 
297 		for (level = LOCKLEVEL; level > 0; --level) {
298 			if (int_at_level & int_level_mask[level]) {
299 				int_at_level &= int_level_mask[level];
300 				if (int_at_level & unhandled)
301 					int_at_level &= unhandled;
302 				else
303 					unhandled |= int_level_mask[level];
304 				break;
305 			}
306 		}
307 
308 		if (level == 0)
309 			break;
310 
311 		/* clear lowest pending irq in the unhandled mask */
312 		unhandled ^= (int_at_level & -int_at_level);
313 		do_IRQ(__ffs(int_at_level), regs);
314 	}
315 
316 	irq_exit();
317 	set_irq_regs(old_regs);
318 }
319 
check_div0(struct pt_regs * regs)320 static bool check_div0(struct pt_regs *regs)
321 {
322 	static const u8 pattern[] = {'D', 'I', 'V', '0'};
323 	const u8 *p;
324 	u8 buf[5];
325 
326 	if (user_mode(regs)) {
327 		if (copy_from_user(buf, (void __user *)regs->pc + 2, 5))
328 			return false;
329 		p = buf;
330 	} else {
331 		p = (const u8 *)regs->pc + 2;
332 	}
333 
334 	return memcmp(p, pattern, sizeof(pattern)) == 0 ||
335 		memcmp(p + 1, pattern, sizeof(pattern)) == 0;
336 }
337 
338 /*
339  * Illegal instruction. Fatal if in kernel space.
340  */
341 
do_illegal_instruction(struct pt_regs * regs)342 static void do_illegal_instruction(struct pt_regs *regs)
343 {
344 #ifdef CONFIG_USER_ABI_CALL0_PROBE
345 	/*
346 	 * When call0 application encounters an illegal instruction fast
347 	 * exception handler will attempt to set PS.WOE and retry failing
348 	 * instruction.
349 	 * If we get here we know that that instruction is also illegal
350 	 * with PS.WOE set, so it's not related to the windowed option
351 	 * hence PS.WOE may be cleared.
352 	 */
353 	if (regs->pc == current_thread_info()->ps_woe_fix_addr)
354 		regs->ps &= ~PS_WOE_MASK;
355 #endif
356 	if (check_div0(regs)) {
357 		do_div0(regs);
358 		return;
359 	}
360 
361 	__die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);
362 
363 	/* If in user mode, send SIGILL signal to current process. */
364 
365 	pr_info_ratelimited("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n",
366 			    current->comm, task_pid_nr(current), regs->pc);
367 	force_sig(SIGILL);
368 }
369 
do_div0(struct pt_regs * regs)370 static void do_div0(struct pt_regs *regs)
371 {
372 	__die_if_kernel("Unhandled division by 0 in kernel", regs, SIGKILL);
373 	force_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)regs->pc);
374 }
375 
376 #ifdef CONFIG_XTENSA_LOAD_STORE
do_load_store(struct pt_regs * regs)377 static void do_load_store(struct pt_regs *regs)
378 {
379 	__die_if_kernel("Unhandled load/store exception in kernel",
380 			regs, SIGKILL);
381 
382 	pr_info_ratelimited("Load/store error to %08lx in '%s' (pid = %d, pc = %#010lx)\n",
383 			    regs->excvaddr, current->comm,
384 			    task_pid_nr(current), regs->pc);
385 	force_sig_fault(SIGBUS, BUS_ADRERR, (void *)regs->excvaddr);
386 }
387 #endif
388 
389 /*
390  * Handle unaligned memory accesses from user space. Kill task.
391  *
392  * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory
393  * accesses causes from user space.
394  */
395 
do_unaligned_user(struct pt_regs * regs)396 static void do_unaligned_user(struct pt_regs *regs)
397 {
398 	__die_if_kernel("Unhandled unaligned exception in kernel",
399 			regs, SIGKILL);
400 
401 	pr_info_ratelimited("Unaligned memory access to %08lx in '%s' "
402 			    "(pid = %d, pc = %#010lx)\n",
403 			    regs->excvaddr, current->comm,
404 			    task_pid_nr(current), regs->pc);
405 	force_sig_fault(SIGBUS, BUS_ADRALN, (void *) regs->excvaddr);
406 }
407 
408 #if XTENSA_HAVE_COPROCESSORS
do_coprocessor(struct pt_regs * regs)409 static void do_coprocessor(struct pt_regs *regs)
410 {
411 	coprocessor_flush_release_all(current_thread_info());
412 }
413 #endif
414 
415 /* Handle debug events.
416  * When CONFIG_HAVE_HW_BREAKPOINT is on this handler is called with
417  * preemption disabled to avoid rescheduling and keep mapping of hardware
418  * breakpoint structures to debug registers intact, so that
419  * DEBUGCAUSE.DBNUM could be used in case of data breakpoint hit.
420  */
do_debug(struct pt_regs * regs)421 static void do_debug(struct pt_regs *regs)
422 {
423 #ifdef CONFIG_HAVE_HW_BREAKPOINT
424 	int ret = check_hw_breakpoint(regs);
425 
426 	preempt_enable();
427 	if (ret == 0)
428 		return;
429 #endif
430 	__die_if_kernel("Breakpoint in kernel", regs, SIGKILL);
431 
432 	/* If in user mode, send SIGTRAP signal to current process */
433 
434 	force_sig(SIGTRAP);
435 }
436 
437 
438 #define set_handler(type, cause, handler)				\
439 	do {								\
440 		unsigned int cpu;					\
441 									\
442 		for_each_possible_cpu(cpu)				\
443 			per_cpu(exc_table, cpu).type[cause] = (handler);\
444 	} while (0)
445 
446 /* Set exception C handler - for temporary use when probing exceptions */
447 
448 xtensa_exception_handler *
trap_set_handler(int cause,xtensa_exception_handler * handler)449 __init trap_set_handler(int cause, xtensa_exception_handler *handler)
450 {
451 	void *previous = per_cpu(exc_table, 0).default_handler[cause];
452 
453 	set_handler(default_handler, cause, handler);
454 	return previous;
455 }
456 
457 
trap_init_excsave(void)458 static void trap_init_excsave(void)
459 {
460 	xtensa_set_sr(this_cpu_ptr(&exc_table), excsave1);
461 }
462 
trap_init_debug(void)463 static void trap_init_debug(void)
464 {
465 	unsigned long debugsave = (unsigned long)this_cpu_ptr(&debug_table);
466 
467 	this_cpu_ptr(&debug_table)->debug_exception = debug_exception;
468 	__asm__ __volatile__("wsr %0, excsave" __stringify(XCHAL_DEBUGLEVEL)
469 			     :: "a"(debugsave));
470 }
471 
472 /*
473  * Initialize dispatch tables.
474  *
475  * The exception vectors are stored compressed the __init section in the
476  * dispatch_init_table. This function initializes the following three tables
477  * from that compressed table:
478  * - fast user		first dispatch table for user exceptions
479  * - fast kernel	first dispatch table for kernel exceptions
480  * - default C-handler	C-handler called by the default fast handler.
481  *
482  * See vectors.S for more details.
483  */
484 
trap_init(void)485 void __init trap_init(void)
486 {
487 	int i;
488 
489 	/* Setup default vectors. */
490 
491 	for (i = 0; i < EXCCAUSE_N; i++) {
492 		set_handler(fast_user_handler, i, user_exception);
493 		set_handler(fast_kernel_handler, i, kernel_exception);
494 		set_handler(default_handler, i, do_unhandled);
495 	}
496 
497 	/* Setup specific handlers. */
498 
499 	for(i = 0; dispatch_init_table[i].cause >= 0; i++) {
500 		int fast = dispatch_init_table[i].fast;
501 		int cause = dispatch_init_table[i].cause;
502 		void *handler = dispatch_init_table[i].handler;
503 
504 		if (fast == 0)
505 			set_handler(default_handler, cause, handler);
506 		if ((fast & USER) != 0)
507 			set_handler(fast_user_handler, cause, handler);
508 		if ((fast & KRNL) != 0)
509 			set_handler(fast_kernel_handler, cause, handler);
510 	}
511 
512 	/* Initialize EXCSAVE_1 to hold the address of the exception table. */
513 	trap_init_excsave();
514 	trap_init_debug();
515 }
516 
517 #ifdef CONFIG_SMP
secondary_trap_init(void)518 void secondary_trap_init(void)
519 {
520 	trap_init_excsave();
521 	trap_init_debug();
522 }
523 #endif
524 
525 /*
526  * This function dumps the current valid window frame and other base registers.
527  */
528 
show_regs(struct pt_regs * regs)529 void show_regs(struct pt_regs * regs)
530 {
531 	int i;
532 
533 	show_regs_print_info(KERN_DEFAULT);
534 
535 	for (i = 0; i < 16; i++) {
536 		if ((i % 8) == 0)
537 			pr_info("a%02d:", i);
538 		pr_cont(" %08lx", regs->areg[i]);
539 	}
540 	pr_cont("\n");
541 	pr_info("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n",
542 		regs->pc, regs->ps, regs->depc, regs->excvaddr);
543 	pr_info("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n",
544 		regs->lbeg, regs->lend, regs->lcount, regs->sar);
545 	if (user_mode(regs))
546 		pr_cont("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n",
547 			regs->windowbase, regs->windowstart, regs->wmask,
548 			regs->syscall);
549 }
550 
show_trace_cb(struct stackframe * frame,void * data)551 static int show_trace_cb(struct stackframe *frame, void *data)
552 {
553 	const char *loglvl = data;
554 
555 	if (kernel_text_address(frame->pc))
556 		printk("%s [<%08lx>] %pB\n",
557 			loglvl, frame->pc, (void *)frame->pc);
558 	return 0;
559 }
560 
show_trace(struct task_struct * task,unsigned long * sp,const char * loglvl)561 static void show_trace(struct task_struct *task, unsigned long *sp,
562 		       const char *loglvl)
563 {
564 	if (!sp)
565 		sp = stack_pointer(task);
566 
567 	printk("%sCall Trace:\n", loglvl);
568 	walk_stackframe(sp, show_trace_cb, (void *)loglvl);
569 }
570 
571 #define STACK_DUMP_ENTRY_SIZE 4
572 #define STACK_DUMP_LINE_SIZE 16
573 static size_t kstack_depth_to_print = CONFIG_PRINT_STACK_DEPTH;
574 
575 struct stack_fragment
576 {
577 	size_t len;
578 	size_t off;
579 	u8 *sp;
580 	const char *loglvl;
581 };
582 
show_stack_fragment_cb(struct stackframe * frame,void * data)583 static int show_stack_fragment_cb(struct stackframe *frame, void *data)
584 {
585 	struct stack_fragment *sf = data;
586 
587 	while (sf->off < sf->len) {
588 		u8 line[STACK_DUMP_LINE_SIZE];
589 		size_t line_len = sf->len - sf->off > STACK_DUMP_LINE_SIZE ?
590 			STACK_DUMP_LINE_SIZE : sf->len - sf->off;
591 		bool arrow = sf->off == 0;
592 
593 		if (frame && frame->sp == (unsigned long)(sf->sp + sf->off))
594 			arrow = true;
595 
596 		__memcpy(line, sf->sp + sf->off, line_len);
597 		print_hex_dump(sf->loglvl, arrow ? "> " : "  ", DUMP_PREFIX_NONE,
598 			       STACK_DUMP_LINE_SIZE, STACK_DUMP_ENTRY_SIZE,
599 			       line, line_len, false);
600 		sf->off += STACK_DUMP_LINE_SIZE;
601 		if (arrow)
602 			return 0;
603 	}
604 	return 1;
605 }
606 
show_stack(struct task_struct * task,unsigned long * sp,const char * loglvl)607 void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
608 {
609 	struct stack_fragment sf;
610 
611 	if (!sp)
612 		sp = stack_pointer(task);
613 
614 	sf.len = min((-(size_t)sp) & (THREAD_SIZE - STACK_DUMP_ENTRY_SIZE),
615 		     kstack_depth_to_print * STACK_DUMP_ENTRY_SIZE);
616 	sf.off = 0;
617 	sf.sp = (u8 *)sp;
618 	sf.loglvl = loglvl;
619 
620 	printk("%sStack:\n", loglvl);
621 	walk_stackframe(sp, show_stack_fragment_cb, &sf);
622 	while (sf.off < sf.len)
623 		show_stack_fragment_cb(NULL, &sf);
624 	show_trace(task, sp, loglvl);
625 }
626 
627 DEFINE_SPINLOCK(die_lock);
628 
die(const char * str,struct pt_regs * regs,long err)629 void __noreturn die(const char * str, struct pt_regs * regs, long err)
630 {
631 	static int die_counter;
632 	const char *pr = "";
633 
634 	if (IS_ENABLED(CONFIG_PREEMPTION))
635 		pr = IS_ENABLED(CONFIG_PREEMPT_RT) ? " PREEMPT_RT" : " PREEMPT";
636 
637 	console_verbose();
638 	spin_lock_irq(&die_lock);
639 
640 	pr_info("%s: sig: %ld [#%d]%s\n", str, err, ++die_counter, pr);
641 	show_regs(regs);
642 	if (!user_mode(regs))
643 		show_stack(NULL, (unsigned long *)regs->areg[1], KERN_INFO);
644 
645 	add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
646 	spin_unlock_irq(&die_lock);
647 
648 	if (in_interrupt())
649 		panic("Fatal exception in interrupt");
650 
651 	if (panic_on_oops)
652 		panic("Fatal exception");
653 
654 	make_task_dead(err);
655 }
656