traps.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 *  linux/arch/arm/kernel/traps.c
  4 *
  5 *  Copyright (C) 1995-2009 Russell King
  6 *  Fragments that appear the same as linux/arch/i386/kernel/traps.c (C) Linus Torvalds
  7 *
  8 *  'traps.c' handles hardware exceptions after we have saved some state in
  9 *  'linux/arch/arm/lib/traps.S'.  Mostly a debugging aid, but will probably
 10 *  kill the offending process.
 11 */
 12#include <linux/signal.h>
 13#include <linux/personality.h>
 14#include <linux/kallsyms.h>
 15#include <linux/spinlock.h>
 16#include <linux/uaccess.h>
 17#include <linux/hardirq.h>
 18#include <linux/kdebug.h>
 19#include <linux/kprobes.h>
 20#include <linux/module.h>
 21#include <linux/kexec.h>
 22#include <linux/bug.h>
 23#include <linux/delay.h>
 24#include <linux/init.h>
 25#include <linux/sched/signal.h>
 26#include <linux/sched/debug.h>
 27#include <linux/sched/task_stack.h>
 28#include <linux/irq.h>
 29#include <linux/vmalloc.h>
 30
 31#include <linux/atomic.h>
 32#include <asm/cacheflush.h>
 33#include <asm/exception.h>
 34#include <asm/spectre.h>
 35#include <asm/unistd.h>
 36#include <asm/traps.h>
 37#include <asm/ptrace.h>
 38#include <asm/unwind.h>
 39#include <asm/tls.h>
 40#include <asm/stacktrace.h>
 41#include <asm/system_misc.h>
 42#include <asm/opcodes.h>
 43
 44
 45static const char *handler[]= {
 46	"prefetch abort",
 47	"data abort",
 48	"address exception",
 49	"interrupt",
 50	"undefined instruction",
 51};
 52
 53void *vectors_page;
 54
 55#ifdef CONFIG_DEBUG_USER
 56unsigned int user_debug;
 57
 58static int __init user_debug_setup(char *str)
 59{
 60	get_option(&str, &user_debug);
 61	return 1;
 62}
 63__setup("user_debug=", user_debug_setup);
 64#endif
 65
 66void dump_backtrace_entry(unsigned long where, unsigned long from,
 67			  unsigned long frame, const char *loglvl)
 68{
 69	unsigned long end = frame + 4 + sizeof(struct pt_regs);
 70
 71	if (IS_ENABLED(CONFIG_UNWINDER_FRAME_POINTER) &&
 72	    IS_ENABLED(CONFIG_CC_IS_GCC) &&
 73	    end > ALIGN(frame, THREAD_SIZE)) {
 74		/*
 75		 * If we are walking past the end of the stack, it may be due
 76		 * to the fact that we are on an IRQ or overflow stack. In this
 77		 * case, we can load the address of the other stack from the
 78		 * frame record.
 79		 */
 80		frame = ((unsigned long *)frame)[-2] - 4;
 81		end = frame + 4 + sizeof(struct pt_regs);
 82	}
 83
 84#ifndef CONFIG_KALLSYMS
 85	printk("%sFunction entered at [<%08lx>] from [<%08lx>]\n",
 86		loglvl, where, from);
 87#elif defined CONFIG_BACKTRACE_VERBOSE
 88	printk("%s[<%08lx>] (%ps) from [<%08lx>] (%pS)\n",
 89		loglvl, where, (void *)where, from, (void *)from);
 90#else
 91	printk("%s %ps from %pS\n", loglvl, (void *)where, (void *)from);
 92#endif
 93
 94	if (in_entry_text(from) && end <= ALIGN(frame, THREAD_SIZE))
 95		dump_mem(loglvl, "Exception stack", frame + 4, end);
 96}
 97
 98void dump_backtrace_stm(u32 *stack, u32 instruction, const char *loglvl)
 99{
100	char str[80], *p;
101	unsigned int x;
102	int reg;
103
104	for (reg = 10, x = 0, p = str; reg >= 0; reg--) {
105		if (instruction & BIT(reg)) {
106			p += sprintf(p, " r%d:%08x", reg, *stack--);
107			if (++x == 6) {
108				x = 0;
109				p = str;
110				printk("%s%s\n", loglvl, str);
111			}
112		}
113	}
114	if (p != str)
115		printk("%s%s\n", loglvl, str);
116}
117
118#ifndef CONFIG_ARM_UNWIND
119/*
120 * Stack pointers should always be within the kernels view of
121 * physical memory.  If it is not there, then we can't dump
122 * out any information relating to the stack.
123 */
124static int verify_stack(unsigned long sp)
125{
126	if (sp < PAGE_OFFSET ||
127	    (!IS_ENABLED(CONFIG_VMAP_STACK) &&
128	     sp > (unsigned long)high_memory && high_memory != NULL))
129		return -EFAULT;
130
131	return 0;
132}
133#endif
134
135/*
136 * Dump out the contents of some memory nicely...
137 */
138void dump_mem(const char *lvl, const char *str, unsigned long bottom,
139	      unsigned long top)
140{
141	unsigned long first;
142	int i;
143
144	printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
145
146	for (first = bottom & ~31; first < top; first += 32) {
147		unsigned long p;
148		char str[sizeof(" 12345678") * 8 + 1];
149
150		memset(str, ' ', sizeof(str));
151		str[sizeof(str) - 1] = '\0';
152
153		for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
154			if (p >= bottom && p < top) {
155				unsigned long val;
156				if (!get_kernel_nofault(val, (unsigned long *)p))
157					sprintf(str + i * 9, " %08lx", val);
158				else
159					sprintf(str + i * 9, " ????????");
160			}
161		}
162		printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
163	}
164}
165
166static void dump_instr(const char *lvl, struct pt_regs *regs)
167{
168	unsigned long addr = instruction_pointer(regs);
169	const int thumb = thumb_mode(regs);
170	const int width = thumb ? 4 : 8;
171	char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
172	int i;
173
174	/*
175	 * Note that we now dump the code first, just in case the backtrace
176	 * kills us.
177	 */
178
179	for (i = -4; i < 1 + !!thumb; i++) {
180		unsigned int val, bad;
181
182		if (thumb) {
183			u16 tmp;
184
185			if (user_mode(regs))
186				bad = get_user(tmp, &((u16 __user *)addr)[i]);
187			else
188				bad = get_kernel_nofault(tmp, &((u16 *)addr)[i]);
189
190			val = __mem_to_opcode_thumb16(tmp);
191		} else {
192			if (user_mode(regs))
193				bad = get_user(val, &((u32 __user *)addr)[i]);
194			else
195				bad = get_kernel_nofault(val, &((u32 *)addr)[i]);
196
197			val = __mem_to_opcode_arm(val);
198		}
199
200		if (!bad)
201			p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
202					width, val);
203		else {
204			p += sprintf(p, "bad PC value");
205			break;
206		}
207	}
208	printk("%sCode: %s\n", lvl, str);
209}
210
211#ifdef CONFIG_ARM_UNWIND
212void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
213		    const char *loglvl)
214{
215	unwind_backtrace(regs, tsk, loglvl);
216}
217#else
218void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
219		    const char *loglvl)
220{
221	unsigned int fp, mode;
222	int ok = 1;
223
224	printk("%sCall trace: ", loglvl);
225
226	if (!tsk)
227		tsk = current;
228
229	if (regs) {
230		fp = frame_pointer(regs);
231		mode = processor_mode(regs);
232	} else if (tsk != current) {
233		fp = thread_saved_fp(tsk);
234		mode = 0x10;
235	} else {
236		asm("mov %0, fp" : "=r" (fp) : : "cc");
237		mode = 0x10;
238	}
239
240	if (!fp) {
241		pr_cont("no frame pointer");
242		ok = 0;
243	} else if (verify_stack(fp)) {
244		pr_cont("invalid frame pointer 0x%08x", fp);
245		ok = 0;
246	} else if (fp < (unsigned long)end_of_stack(tsk))
247		pr_cont("frame pointer underflow");
248	pr_cont("\n");
249
250	if (ok)
251		c_backtrace(fp, mode, loglvl);
252}
253#endif
254
255void show_stack(struct task_struct *tsk, unsigned long *sp, const char *loglvl)
256{
257	dump_backtrace(NULL, tsk, loglvl);
258	barrier();
259}
260
261#ifdef CONFIG_SMP
262#define S_SMP " SMP"
263#else
264#define S_SMP ""
265#endif
266#ifdef CONFIG_THUMB2_KERNEL
267#define S_ISA " THUMB2"
268#else
269#define S_ISA " ARM"
270#endif
271
272static int __die(const char *str, int err, struct pt_regs *regs)
273{
274	struct task_struct *tsk = current;
275	static int die_counter;
276	int ret;
277
278	pr_emerg("Internal error: %s: %x [#%d]" S_SMP S_ISA "\n",
279		 str, err, ++die_counter);
280
281	/* trap and error numbers are mostly meaningless on ARM */
282	ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
283	if (ret == NOTIFY_STOP)
284		return 1;
285
286	print_modules();
287	__show_regs(regs);
288	__show_regs_alloc_free(regs);
289	pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
290		 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
291
292	if (!user_mode(regs) || in_interrupt()) {
293		dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
294			 ALIGN(regs->ARM_sp - THREAD_SIZE, THREAD_ALIGN)
295			 + THREAD_SIZE);
296		dump_backtrace(regs, tsk, KERN_EMERG);
297		dump_instr(KERN_EMERG, regs);
298	}
299
300	return 0;
301}
302
303static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
304static int die_owner = -1;
305static unsigned int die_nest_count;
306
307static unsigned long oops_begin(void)
308{
309	int cpu;
310	unsigned long flags;
311
312	oops_enter();
313
314	/* racy, but better than risking deadlock. */
315	raw_local_irq_save(flags);
316	cpu = smp_processor_id();
317	if (!arch_spin_trylock(&die_lock)) {
318		if (cpu == die_owner)
319			/* nested oops. should stop eventually */;
320		else
321			arch_spin_lock(&die_lock);
322	}
323	die_nest_count++;
324	die_owner = cpu;
325	console_verbose();
326	bust_spinlocks(1);
327	return flags;
328}
329
330static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
331{
332	if (regs && kexec_should_crash(current))
333		crash_kexec(regs);
334
335	bust_spinlocks(0);
336	die_owner = -1;
337	add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
338	die_nest_count--;
339	if (!die_nest_count)
340		/* Nest count reaches zero, release the lock. */
341		arch_spin_unlock(&die_lock);
342	raw_local_irq_restore(flags);
343	oops_exit();
344
345	if (in_interrupt())
346		panic("Fatal exception in interrupt");
347	if (panic_on_oops)
348		panic("Fatal exception");
349	if (signr)
350		make_task_dead(signr);
351}
352
353/*
354 * This function is protected against re-entrancy.
355 */
356void die(const char *str, struct pt_regs *regs, int err)
357{
358	enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
359	unsigned long flags = oops_begin();
360	int sig = SIGSEGV;
361
362	if (!user_mode(regs))
363		bug_type = report_bug(regs->ARM_pc, regs);
364	if (bug_type != BUG_TRAP_TYPE_NONE)
365		str = "Oops - BUG";
366
367	if (__die(str, err, regs))
368		sig = 0;
369
370	oops_end(flags, regs, sig);
371}
372
373void arm_notify_die(const char *str, struct pt_regs *regs,
374		int signo, int si_code, void __user *addr,
375		unsigned long err, unsigned long trap)
376{
377	if (user_mode(regs)) {
378		current->thread.error_code = err;
379		current->thread.trap_no = trap;
380
381		force_sig_fault(signo, si_code, addr);
382	} else {
383		die(str, regs, err);
384	}
385}
386
387#ifdef CONFIG_GENERIC_BUG
388
389int is_valid_bugaddr(unsigned long pc)
390{
391#ifdef CONFIG_THUMB2_KERNEL
392	u16 bkpt;
393	u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);
394#else
395	u32 bkpt;
396	u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
397#endif
398
399	if (get_kernel_nofault(bkpt, (void *)pc))
400		return 0;
401
402	return bkpt == insn;
403}
404
405#endif
406
407static LIST_HEAD(undef_hook);
408static DEFINE_RAW_SPINLOCK(undef_lock);
409
410void register_undef_hook(struct undef_hook *hook)
411{
412	unsigned long flags;
413
414	raw_spin_lock_irqsave(&undef_lock, flags);
415	list_add(&hook->node, &undef_hook);
416	raw_spin_unlock_irqrestore(&undef_lock, flags);
417}
418
419void unregister_undef_hook(struct undef_hook *hook)
420{
421	unsigned long flags;
422
423	raw_spin_lock_irqsave(&undef_lock, flags);
424	list_del(&hook->node);
425	raw_spin_unlock_irqrestore(&undef_lock, flags);
426}
427
428static nokprobe_inline
429int call_undef_hook(struct pt_regs *regs, unsigned int instr)
430{
431	struct undef_hook *hook;
432	unsigned long flags;
433	int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
434
435	raw_spin_lock_irqsave(&undef_lock, flags);
436	list_for_each_entry(hook, &undef_hook, node)
437		if ((instr & hook->instr_mask) == hook->instr_val &&
438		    (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
439			fn = hook->fn;
440	raw_spin_unlock_irqrestore(&undef_lock, flags);
441
442	return fn ? fn(regs, instr) : 1;
443}
444
445asmlinkage void do_undefinstr(struct pt_regs *regs)
446{
447	unsigned int instr;
448	void __user *pc;
449
450	pc = (void __user *)instruction_pointer(regs);
451
452	if (processor_mode(regs) == SVC_MODE) {
453#ifdef CONFIG_THUMB2_KERNEL
454		if (thumb_mode(regs)) {
455			instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
456			if (is_wide_instruction(instr)) {
457				u16 inst2;
458				inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
459				instr = __opcode_thumb32_compose(instr, inst2);
460			}
461		} else
462#endif
463			instr = __mem_to_opcode_arm(*(u32 *) pc);
464	} else if (thumb_mode(regs)) {
465		if (get_user(instr, (u16 __user *)pc))
466			goto die_sig;
467		instr = __mem_to_opcode_thumb16(instr);
468		if (is_wide_instruction(instr)) {
469			unsigned int instr2;
470			if (get_user(instr2, (u16 __user *)pc+1))
471				goto die_sig;
472			instr2 = __mem_to_opcode_thumb16(instr2);
473			instr = __opcode_thumb32_compose(instr, instr2);
474		}
475	} else {
476		if (get_user(instr, (u32 __user *)pc))
477			goto die_sig;
478		instr = __mem_to_opcode_arm(instr);
479	}
480
481	if (call_undef_hook(regs, instr) == 0)
482		return;
483
484die_sig:
485#ifdef CONFIG_DEBUG_USER
486	if (user_debug & UDBG_UNDEFINED) {
487		pr_info("%s (%d): undefined instruction: pc=%px\n",
488			current->comm, task_pid_nr(current), pc);
489		__show_regs(regs);
490		dump_instr(KERN_INFO, regs);
491	}
492#endif
493	arm_notify_die("Oops - undefined instruction", regs,
494		       SIGILL, ILL_ILLOPC, pc, 0, 6);
495}
496NOKPROBE_SYMBOL(do_undefinstr)
497
498/*
499 * Handle FIQ similarly to NMI on x86 systems.
500 *
501 * The runtime environment for NMIs is extremely restrictive
502 * (NMIs can pre-empt critical sections meaning almost all locking is
503 * forbidden) meaning this default FIQ handling must only be used in
504 * circumstances where non-maskability improves robustness, such as
505 * watchdog or debug logic.
506 *
507 * This handler is not appropriate for general purpose use in drivers
508 * platform code and can be overrideen using set_fiq_handler.
509 */
510asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs)
511{
512	struct pt_regs *old_regs = set_irq_regs(regs);
513
514	nmi_enter();
515
516	/* nop. FIQ handlers for special arch/arm features can be added here. */
517
518	nmi_exit();
519
520	set_irq_regs(old_regs);
521}
522
523/*
524 * bad_mode handles the impossible case in the vectors.  If you see one of
525 * these, then it's extremely serious, and could mean you have buggy hardware.
526 * It never returns, and never tries to sync.  We hope that we can at least
527 * dump out some state information...
528 */
529asmlinkage void bad_mode(struct pt_regs *regs, int reason)
530{
531	console_verbose();
532
533	pr_crit("Bad mode in %s handler detected\n", handler[reason]);
534
535	die("Oops - bad mode", regs, 0);
536	local_irq_disable();
537	panic("bad mode");
538}
539
540static int bad_syscall(int n, struct pt_regs *regs)
541{
542	if ((current->personality & PER_MASK) != PER_LINUX) {
543		send_sig(SIGSEGV, current, 1);
544		return regs->ARM_r0;
545	}
546
547#ifdef CONFIG_DEBUG_USER
548	if (user_debug & UDBG_SYSCALL) {
549		pr_err("[%d] %s: obsolete system call %08x.\n",
550			task_pid_nr(current), current->comm, n);
551		dump_instr(KERN_ERR, regs);
552	}
553#endif
554
555	arm_notify_die("Oops - bad syscall", regs, SIGILL, ILL_ILLTRP,
556		       (void __user *)instruction_pointer(regs) -
557			 (thumb_mode(regs) ? 2 : 4),
558		       n, 0);
559
560	return regs->ARM_r0;
561}
562
563static inline int
564__do_cache_op(unsigned long start, unsigned long end)
565{
566	unsigned int ua_flags;
567	int ret;
568
569	do {
570		unsigned long chunk = min(PAGE_SIZE, end - start);
571
572		if (fatal_signal_pending(current))
573			return 0;
574
575		ua_flags = uaccess_save_and_enable();
576		ret = flush_icache_user_range(start, start + chunk);
577		uaccess_restore(ua_flags);
578		if (ret)
579			return ret;
580
581		cond_resched();
582		start += chunk;
583	} while (start < end);
584
585	return 0;
586}
587
588static inline int
589do_cache_op(unsigned long start, unsigned long end, int flags)
590{
591	if (end < start || flags)
592		return -EINVAL;
593
594	if (!access_ok((void __user *)start, end - start))
595		return -EFAULT;
596
597	return __do_cache_op(start, end);
598}
599
600/*
601 * Handle all unrecognised system calls.
602 *  0x9f0000 - 0x9fffff are some more esoteric system calls
603 */
604#define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
605asmlinkage int arm_syscall(int no, struct pt_regs *regs)
606{
607	if ((no >> 16) != (__ARM_NR_BASE>> 16))
608		return bad_syscall(no, regs);
609
610	switch (no & 0xffff) {
611	case 0: /* branch through 0 */
612		arm_notify_die("branch through zero", regs,
613			       SIGSEGV, SEGV_MAPERR, NULL, 0, 0);
614		return 0;
615
616	case NR(breakpoint): /* SWI BREAK_POINT */
617		regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
618		ptrace_break(regs);
619		return regs->ARM_r0;
620
621	/*
622	 * Flush a region from virtual address 'r0' to virtual address 'r1'
623	 * _exclusive_.  There is no alignment requirement on either address;
624	 * user space does not need to know the hardware cache layout.
625	 *
626	 * r2 contains flags.  It should ALWAYS be passed as ZERO until it
627	 * is defined to be something else.  For now we ignore it, but may
628	 * the fires of hell burn in your belly if you break this rule. ;)
629	 *
630	 * (at a later date, we may want to allow this call to not flush
631	 * various aspects of the cache.  Passing '0' will guarantee that
632	 * everything necessary gets flushed to maintain consistency in
633	 * the specified region).
634	 */
635	case NR(cacheflush):
636		return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
637
638	case NR(usr26):
639		if (!(elf_hwcap & HWCAP_26BIT))
640			break;
641		regs->ARM_cpsr &= ~MODE32_BIT;
642		return regs->ARM_r0;
643
644	case NR(usr32):
645		if (!(elf_hwcap & HWCAP_26BIT))
646			break;
647		regs->ARM_cpsr |= MODE32_BIT;
648		return regs->ARM_r0;
649
650	case NR(set_tls):
651		set_tls(regs->ARM_r0);
652		return 0;
653
654	case NR(get_tls):
655		return current_thread_info()->tp_value[0];
656
657	default:
658		/* Calls 9f00xx..9f07ff are defined to return -ENOSYS
659		   if not implemented, rather than raising SIGILL.  This
660		   way the calling program can gracefully determine whether
661		   a feature is supported.  */
662		if ((no & 0xffff) <= 0x7ff)
663			return -ENOSYS;
664		break;
665	}
666#ifdef CONFIG_DEBUG_USER
667	/*
668	 * experience shows that these seem to indicate that
669	 * something catastrophic has happened
670	 */
671	if (user_debug & UDBG_SYSCALL) {
672		pr_err("[%d] %s: arm syscall %d\n",
673		       task_pid_nr(current), current->comm, no);
674		dump_instr(KERN_ERR, regs);
675		if (user_mode(regs)) {
676			__show_regs(regs);
677			c_backtrace(frame_pointer(regs), processor_mode(regs), KERN_ERR);
678		}
679	}
680#endif
681	arm_notify_die("Oops - bad syscall(2)", regs, SIGILL, ILL_ILLTRP,
682		       (void __user *)instruction_pointer(regs) -
683			 (thumb_mode(regs) ? 2 : 4),
684		       no, 0);
685	return 0;
686}
687
688#ifdef CONFIG_TLS_REG_EMUL
689
690/*
691 * We might be running on an ARMv6+ processor which should have the TLS
692 * register but for some reason we can't use it, or maybe an SMP system
693 * using a pre-ARMv6 processor (there are apparently a few prototypes like
694 * that in existence) and therefore access to that register must be
695 * emulated.
696 */
697
698static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
699{
700	int reg = (instr >> 12) & 15;
701	if (reg == 15)
702		return 1;
703	regs->uregs[reg] = current_thread_info()->tp_value[0];
704	regs->ARM_pc += 4;
705	return 0;
706}
707
708static struct undef_hook arm_mrc_hook = {
709	.instr_mask	= 0x0fff0fff,
710	.instr_val	= 0x0e1d0f70,
711	.cpsr_mask	= PSR_T_BIT,
712	.cpsr_val	= 0,
713	.fn		= get_tp_trap,
714};
715
716static int __init arm_mrc_hook_init(void)
717{
718	register_undef_hook(&arm_mrc_hook);
719	return 0;
720}
721
722late_initcall(arm_mrc_hook_init);
723
724#endif
725
726/*
727 * A data abort trap was taken, but we did not handle the instruction.
728 * Try to abort the user program, or panic if it was the kernel.
729 */
730asmlinkage void
731baddataabort(int code, unsigned long instr, struct pt_regs *regs)
732{
733	unsigned long addr = instruction_pointer(regs);
734
735#ifdef CONFIG_DEBUG_USER
736	if (user_debug & UDBG_BADABORT) {
737		pr_err("8<--- cut here ---\n");
738		pr_err("[%d] %s: bad data abort: code %d instr 0x%08lx\n",
739		       task_pid_nr(current), current->comm, code, instr);
740		dump_instr(KERN_ERR, regs);
741		show_pte(KERN_ERR, current->mm, addr);
742	}
743#endif
744
745	arm_notify_die("unknown data abort code", regs,
746		       SIGILL, ILL_ILLOPC, (void __user *)addr, instr, 0);
747}
748
749void __readwrite_bug(const char *fn)
750{
751	pr_err("%s called, but not implemented\n", fn);
752	BUG();
753}
754EXPORT_SYMBOL(__readwrite_bug);
755
756#ifdef CONFIG_MMU
757void __pte_error(const char *file, int line, pte_t pte)
758{
759	pr_err("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
760}
761
762void __pmd_error(const char *file, int line, pmd_t pmd)
763{
764	pr_err("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
765}
766
767void __pgd_error(const char *file, int line, pgd_t pgd)
768{
769	pr_err("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
770}
771#endif
772
773asmlinkage void __div0(void)
774{
775	pr_err("Division by zero in kernel.\n");
776	dump_stack();
777}
778EXPORT_SYMBOL(__div0);
779
780void abort(void)
781{
782	BUG();
783
784	/* if that doesn't kill us, halt */
785	panic("Oops failed to kill thread");
786}
787
788#ifdef CONFIG_KUSER_HELPERS
789static void __init kuser_init(void *vectors)
790{
791	extern char __kuser_helper_start[], __kuser_helper_end[];
792	int kuser_sz = __kuser_helper_end - __kuser_helper_start;
793
794	memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
795
796	/*
797	 * vectors + 0xfe0 = __kuser_get_tls
798	 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
799	 */
800	if (tls_emu || has_tls_reg)
801		memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
802}
803#else
804static inline void __init kuser_init(void *vectors)
805{
806}
807#endif
808
809#ifndef CONFIG_CPU_V7M
810static void copy_from_lma(void *vma, void *lma_start, void *lma_end)
811{
812	memcpy(vma, lma_start, lma_end - lma_start);
813}
814
815static void flush_vectors(void *vma, size_t offset, size_t size)
816{
817	unsigned long start = (unsigned long)vma + offset;
818	unsigned long end = start + size;
819
820	flush_icache_range(start, end);
821}
822
823#ifdef CONFIG_HARDEN_BRANCH_HISTORY
824int spectre_bhb_update_vectors(unsigned int method)
825{
826	extern char __vectors_bhb_bpiall_start[], __vectors_bhb_bpiall_end[];
827	extern char __vectors_bhb_loop8_start[], __vectors_bhb_loop8_end[];
828	void *vec_start, *vec_end;
829
830	if (system_state >= SYSTEM_FREEING_INITMEM) {
831		pr_err("CPU%u: Spectre BHB workaround too late - system vulnerable\n",
832		       smp_processor_id());
833		return SPECTRE_VULNERABLE;
834	}
835
836	switch (method) {
837	case SPECTRE_V2_METHOD_LOOP8:
838		vec_start = __vectors_bhb_loop8_start;
839		vec_end = __vectors_bhb_loop8_end;
840		break;
841
842	case SPECTRE_V2_METHOD_BPIALL:
843		vec_start = __vectors_bhb_bpiall_start;
844		vec_end = __vectors_bhb_bpiall_end;
845		break;
846
847	default:
848		pr_err("CPU%u: unknown Spectre BHB state %d\n",
849		       smp_processor_id(), method);
850		return SPECTRE_VULNERABLE;
851	}
852
853	copy_from_lma(vectors_page, vec_start, vec_end);
854	flush_vectors(vectors_page, 0, vec_end - vec_start);
855
856	return SPECTRE_MITIGATED;
857}
858#endif
859
860void __init early_trap_init(void *vectors_base)
861{
862	extern char __stubs_start[], __stubs_end[];
863	extern char __vectors_start[], __vectors_end[];
864	unsigned i;
865
866	vectors_page = vectors_base;
867
868	/*
869	 * Poison the vectors page with an undefined instruction.  This
870	 * instruction is chosen to be undefined for both ARM and Thumb
871	 * ISAs.  The Thumb version is an undefined instruction with a
872	 * branch back to the undefined instruction.
873	 */
874	for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
875		((u32 *)vectors_base)[i] = 0xe7fddef1;
876
877	/*
878	 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
879	 * into the vector page, mapped at 0xffff0000, and ensure these
880	 * are visible to the instruction stream.
881	 */
882	copy_from_lma(vectors_base, __vectors_start, __vectors_end);
883	copy_from_lma(vectors_base + 0x1000, __stubs_start, __stubs_end);
884
885	kuser_init(vectors_base);
886
887	flush_vectors(vectors_base, 0, PAGE_SIZE * 2);
888}
889#else /* ifndef CONFIG_CPU_V7M */
890void __init early_trap_init(void *vectors_base)
891{
892	/*
893	 * on V7-M there is no need to copy the vector table to a dedicated
894	 * memory area. The address is configurable and so a table in the kernel
895	 * image can be used.
896	 */
897}
898#endif
899
900#ifdef CONFIG_VMAP_STACK
901
902DECLARE_PER_CPU(u8 *, irq_stack_ptr);
903
904asmlinkage DEFINE_PER_CPU(u8 *, overflow_stack_ptr);
905
906static int __init allocate_overflow_stacks(void)
907{
908	u8 *stack;
909	int cpu;
910
911	for_each_possible_cpu(cpu) {
912		stack = (u8 *)__get_free_page(GFP_KERNEL);
913		if (WARN_ON(!stack))
914			return -ENOMEM;
915		per_cpu(overflow_stack_ptr, cpu) = &stack[OVERFLOW_STACK_SIZE];
916	}
917	return 0;
918}
919early_initcall(allocate_overflow_stacks);
920
921asmlinkage void handle_bad_stack(struct pt_regs *regs)
922{
923	unsigned long tsk_stk = (unsigned long)current->stack;
924#ifdef CONFIG_IRQSTACKS
925	unsigned long irq_stk = (unsigned long)raw_cpu_read(irq_stack_ptr);
926#endif
927	unsigned long ovf_stk = (unsigned long)raw_cpu_read(overflow_stack_ptr);
928
929	console_verbose();
930	pr_emerg("Insufficient stack space to handle exception!");
931
932	pr_emerg("Task stack:     [0x%08lx..0x%08lx]\n",
933		 tsk_stk, tsk_stk + THREAD_SIZE);
934#ifdef CONFIG_IRQSTACKS
935	pr_emerg("IRQ stack:      [0x%08lx..0x%08lx]\n",
936		 irq_stk - THREAD_SIZE, irq_stk);
937#endif
938	pr_emerg("Overflow stack: [0x%08lx..0x%08lx]\n",
939		 ovf_stk - OVERFLOW_STACK_SIZE, ovf_stk);
940
941	die("kernel stack overflow", regs, 0);
942}
943
944#ifndef CONFIG_ARM_LPAE
945/*
946 * Normally, we rely on the logic in do_translation_fault() to update stale PMD
947 * entries covering the vmalloc space in a task's page tables when it first
948 * accesses the region in question. Unfortunately, this is not sufficient when
949 * the task stack resides in the vmalloc region, as do_translation_fault() is a
950 * C function that needs a stack to run.
951 *
952 * So we need to ensure that these PMD entries are up to date *before* the MM
953 * switch. As we already have some logic in the MM switch path that takes care
954 * of this, let's trigger it by bumping the counter every time the core vmalloc
955 * code modifies a PMD entry in the vmalloc region. Use release semantics on
956 * the store so that other CPUs observing the counter's new value are
957 * guaranteed to see the updated page table entries as well.
958 */
959void arch_sync_kernel_mappings(unsigned long start, unsigned long end)
960{
961	if (start < VMALLOC_END && end > VMALLOC_START)
962		atomic_inc_return_release(&init_mm.context.vmalloc_seq);
963}
964#endif
965#endif