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_PREEMPT
262#define S_PREEMPT " PREEMPT"
263#elif defined(CONFIG_PREEMPT_RT)
264#define S_PREEMPT " PREEMPT_RT"
265#else
266#define S_PREEMPT ""
267#endif
268#ifdef CONFIG_SMP
269#define S_SMP " SMP"
270#else
271#define S_SMP ""
272#endif
273#ifdef CONFIG_THUMB2_KERNEL
274#define S_ISA " THUMB2"
275#else
276#define S_ISA " ARM"
277#endif
278
279static int __die(const char *str, int err, struct pt_regs *regs)
280{
281	struct task_struct *tsk = current;
282	static int die_counter;
283	int ret;
284
285	pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP S_ISA "\n",
286	         str, err, ++die_counter);
287
288	/* trap and error numbers are mostly meaningless on ARM */
289	ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
290	if (ret == NOTIFY_STOP)
291		return 1;
292
293	print_modules();
294	__show_regs(regs);
295	__show_regs_alloc_free(regs);
296	pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
297		 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
298
299	if (!user_mode(regs) || in_interrupt()) {
300		dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
301			 ALIGN(regs->ARM_sp - THREAD_SIZE, THREAD_ALIGN)
302			 + THREAD_SIZE);
303		dump_backtrace(regs, tsk, KERN_EMERG);
304		dump_instr(KERN_EMERG, regs);
305	}
306
307	return 0;
308}
309
310static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
311static int die_owner = -1;
312static unsigned int die_nest_count;
313
314static unsigned long oops_begin(void)
315{
316	int cpu;
317	unsigned long flags;
318
319	oops_enter();
320
321	/* racy, but better than risking deadlock. */
322	raw_local_irq_save(flags);
323	cpu = smp_processor_id();
324	if (!arch_spin_trylock(&die_lock)) {
325		if (cpu == die_owner)
326			/* nested oops. should stop eventually */;
327		else
328			arch_spin_lock(&die_lock);
329	}
330	die_nest_count++;
331	die_owner = cpu;
332	console_verbose();
333	bust_spinlocks(1);
334	return flags;
335}
336
337static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
338{
339	if (regs && kexec_should_crash(current))
340		crash_kexec(regs);
341
342	bust_spinlocks(0);
343	die_owner = -1;
344	add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
345	die_nest_count--;
346	if (!die_nest_count)
347		/* Nest count reaches zero, release the lock. */
348		arch_spin_unlock(&die_lock);
349	raw_local_irq_restore(flags);
350	oops_exit();
351
352	if (in_interrupt())
353		panic("Fatal exception in interrupt");
354	if (panic_on_oops)
355		panic("Fatal exception");
356	if (signr)
357		make_task_dead(signr);
358}
359
360/*
361 * This function is protected against re-entrancy.
362 */
363void die(const char *str, struct pt_regs *regs, int err)
364{
365	enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
366	unsigned long flags = oops_begin();
367	int sig = SIGSEGV;
368
369	if (!user_mode(regs))
370		bug_type = report_bug(regs->ARM_pc, regs);
371	if (bug_type != BUG_TRAP_TYPE_NONE)
372		str = "Oops - BUG";
373
374	if (__die(str, err, regs))
375		sig = 0;
376
377	oops_end(flags, regs, sig);
378}
379
380void arm_notify_die(const char *str, struct pt_regs *regs,
381		int signo, int si_code, void __user *addr,
382		unsigned long err, unsigned long trap)
383{
384	if (user_mode(regs)) {
385		current->thread.error_code = err;
386		current->thread.trap_no = trap;
387
388		force_sig_fault(signo, si_code, addr);
389	} else {
390		die(str, regs, err);
391	}
392}
393
394#ifdef CONFIG_GENERIC_BUG
395
396int is_valid_bugaddr(unsigned long pc)
397{
398#ifdef CONFIG_THUMB2_KERNEL
399	u16 bkpt;
400	u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);
401#else
402	u32 bkpt;
403	u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
404#endif
405
406	if (get_kernel_nofault(bkpt, (void *)pc))
407		return 0;
408
409	return bkpt == insn;
410}
411
412#endif
413
414static LIST_HEAD(undef_hook);
415static DEFINE_RAW_SPINLOCK(undef_lock);
416
417void register_undef_hook(struct undef_hook *hook)
418{
419	unsigned long flags;
420
421	raw_spin_lock_irqsave(&undef_lock, flags);
422	list_add(&hook->node, &undef_hook);
423	raw_spin_unlock_irqrestore(&undef_lock, flags);
424}
425
426void unregister_undef_hook(struct undef_hook *hook)
427{
428	unsigned long flags;
429
430	raw_spin_lock_irqsave(&undef_lock, flags);
431	list_del(&hook->node);
432	raw_spin_unlock_irqrestore(&undef_lock, flags);
433}
434
435static nokprobe_inline
436int call_undef_hook(struct pt_regs *regs, unsigned int instr)
437{
438	struct undef_hook *hook;
439	unsigned long flags;
440	int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
441
442	raw_spin_lock_irqsave(&undef_lock, flags);
443	list_for_each_entry(hook, &undef_hook, node)
444		if ((instr & hook->instr_mask) == hook->instr_val &&
445		    (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
446			fn = hook->fn;
447	raw_spin_unlock_irqrestore(&undef_lock, flags);
448
449	return fn ? fn(regs, instr) : 1;
450}
451
452asmlinkage void do_undefinstr(struct pt_regs *regs)
453{
454	unsigned int instr;
455	void __user *pc;
456
457	pc = (void __user *)instruction_pointer(regs);
458
459	if (processor_mode(regs) == SVC_MODE) {
460#ifdef CONFIG_THUMB2_KERNEL
461		if (thumb_mode(regs)) {
462			instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
463			if (is_wide_instruction(instr)) {
464				u16 inst2;
465				inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
466				instr = __opcode_thumb32_compose(instr, inst2);
467			}
468		} else
469#endif
470			instr = __mem_to_opcode_arm(*(u32 *) pc);
471	} else if (thumb_mode(regs)) {
472		if (get_user(instr, (u16 __user *)pc))
473			goto die_sig;
474		instr = __mem_to_opcode_thumb16(instr);
475		if (is_wide_instruction(instr)) {
476			unsigned int instr2;
477			if (get_user(instr2, (u16 __user *)pc+1))
478				goto die_sig;
479			instr2 = __mem_to_opcode_thumb16(instr2);
480			instr = __opcode_thumb32_compose(instr, instr2);
481		}
482	} else {
483		if (get_user(instr, (u32 __user *)pc))
484			goto die_sig;
485		instr = __mem_to_opcode_arm(instr);
486	}
487
488	if (call_undef_hook(regs, instr) == 0)
489		return;
490
491die_sig:
492#ifdef CONFIG_DEBUG_USER
493	if (user_debug & UDBG_UNDEFINED) {
494		pr_info("%s (%d): undefined instruction: pc=%px\n",
495			current->comm, task_pid_nr(current), pc);
496		__show_regs(regs);
497		dump_instr(KERN_INFO, regs);
498	}
499#endif
500	arm_notify_die("Oops - undefined instruction", regs,
501		       SIGILL, ILL_ILLOPC, pc, 0, 6);
502}
503NOKPROBE_SYMBOL(do_undefinstr)
504
505/*
506 * Handle FIQ similarly to NMI on x86 systems.
507 *
508 * The runtime environment for NMIs is extremely restrictive
509 * (NMIs can pre-empt critical sections meaning almost all locking is
510 * forbidden) meaning this default FIQ handling must only be used in
511 * circumstances where non-maskability improves robustness, such as
512 * watchdog or debug logic.
513 *
514 * This handler is not appropriate for general purpose use in drivers
515 * platform code and can be overrideen using set_fiq_handler.
516 */
517asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs)
518{
519	struct pt_regs *old_regs = set_irq_regs(regs);
520
521	nmi_enter();
522
523	/* nop. FIQ handlers for special arch/arm features can be added here. */
524
525	nmi_exit();
526
527	set_irq_regs(old_regs);
528}
529
530/*
531 * bad_mode handles the impossible case in the vectors.  If you see one of
532 * these, then it's extremely serious, and could mean you have buggy hardware.
533 * It never returns, and never tries to sync.  We hope that we can at least
534 * dump out some state information...
535 */
536asmlinkage void bad_mode(struct pt_regs *regs, int reason)
537{
538	console_verbose();
539
540	pr_crit("Bad mode in %s handler detected\n", handler[reason]);
541
542	die("Oops - bad mode", regs, 0);
543	local_irq_disable();
544	panic("bad mode");
545}
546
547static int bad_syscall(int n, struct pt_regs *regs)
548{
549	if ((current->personality & PER_MASK) != PER_LINUX) {
550		send_sig(SIGSEGV, current, 1);
551		return regs->ARM_r0;
552	}
553
554#ifdef CONFIG_DEBUG_USER
555	if (user_debug & UDBG_SYSCALL) {
556		pr_err("[%d] %s: obsolete system call %08x.\n",
557			task_pid_nr(current), current->comm, n);
558		dump_instr(KERN_ERR, regs);
559	}
560#endif
561
562	arm_notify_die("Oops - bad syscall", regs, SIGILL, ILL_ILLTRP,
563		       (void __user *)instruction_pointer(regs) -
564			 (thumb_mode(regs) ? 2 : 4),
565		       n, 0);
566
567	return regs->ARM_r0;
568}
569
570static inline int
571__do_cache_op(unsigned long start, unsigned long end)
572{
573	unsigned int ua_flags;
574	int ret;
575
576	do {
577		unsigned long chunk = min(PAGE_SIZE, end - start);
578
579		if (fatal_signal_pending(current))
580			return 0;
581
582		ua_flags = uaccess_save_and_enable();
583		ret = flush_icache_user_range(start, start + chunk);
584		uaccess_restore(ua_flags);
585		if (ret)
586			return ret;
587
588		cond_resched();
589		start += chunk;
590	} while (start < end);
591
592	return 0;
593}
594
595static inline int
596do_cache_op(unsigned long start, unsigned long end, int flags)
597{
598	if (end < start || flags)
599		return -EINVAL;
600
601	if (!access_ok((void __user *)start, end - start))
602		return -EFAULT;
603
604	return __do_cache_op(start, end);
605}
606
607/*
608 * Handle all unrecognised system calls.
609 *  0x9f0000 - 0x9fffff are some more esoteric system calls
610 */
611#define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
612asmlinkage int arm_syscall(int no, struct pt_regs *regs)
613{
614	if ((no >> 16) != (__ARM_NR_BASE>> 16))
615		return bad_syscall(no, regs);
616
617	switch (no & 0xffff) {
618	case 0: /* branch through 0 */
619		arm_notify_die("branch through zero", regs,
620			       SIGSEGV, SEGV_MAPERR, NULL, 0, 0);
621		return 0;
622
623	case NR(breakpoint): /* SWI BREAK_POINT */
624		regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
625		ptrace_break(regs);
626		return regs->ARM_r0;
627
628	/*
629	 * Flush a region from virtual address 'r0' to virtual address 'r1'
630	 * _exclusive_.  There is no alignment requirement on either address;
631	 * user space does not need to know the hardware cache layout.
632	 *
633	 * r2 contains flags.  It should ALWAYS be passed as ZERO until it
634	 * is defined to be something else.  For now we ignore it, but may
635	 * the fires of hell burn in your belly if you break this rule. ;)
636	 *
637	 * (at a later date, we may want to allow this call to not flush
638	 * various aspects of the cache.  Passing '0' will guarantee that
639	 * everything necessary gets flushed to maintain consistency in
640	 * the specified region).
641	 */
642	case NR(cacheflush):
643		return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
644
645	case NR(usr26):
646		if (!(elf_hwcap & HWCAP_26BIT))
647			break;
648		regs->ARM_cpsr &= ~MODE32_BIT;
649		return regs->ARM_r0;
650
651	case NR(usr32):
652		if (!(elf_hwcap & HWCAP_26BIT))
653			break;
654		regs->ARM_cpsr |= MODE32_BIT;
655		return regs->ARM_r0;
656
657	case NR(set_tls):
658		set_tls(regs->ARM_r0);
659		return 0;
660
661	case NR(get_tls):
662		return current_thread_info()->tp_value[0];
663
664	default:
665		/* Calls 9f00xx..9f07ff are defined to return -ENOSYS
666		   if not implemented, rather than raising SIGILL.  This
667		   way the calling program can gracefully determine whether
668		   a feature is supported.  */
669		if ((no & 0xffff) <= 0x7ff)
670			return -ENOSYS;
671		break;
672	}
673#ifdef CONFIG_DEBUG_USER
674	/*
675	 * experience shows that these seem to indicate that
676	 * something catastrophic has happened
677	 */
678	if (user_debug & UDBG_SYSCALL) {
679		pr_err("[%d] %s: arm syscall %d\n",
680		       task_pid_nr(current), current->comm, no);
681		dump_instr(KERN_ERR, regs);
682		if (user_mode(regs)) {
683			__show_regs(regs);
684			c_backtrace(frame_pointer(regs), processor_mode(regs), KERN_ERR);
685		}
686	}
687#endif
688	arm_notify_die("Oops - bad syscall(2)", regs, SIGILL, ILL_ILLTRP,
689		       (void __user *)instruction_pointer(regs) -
690			 (thumb_mode(regs) ? 2 : 4),
691		       no, 0);
692	return 0;
693}
694
695#ifdef CONFIG_TLS_REG_EMUL
696
697/*
698 * We might be running on an ARMv6+ processor which should have the TLS
699 * register but for some reason we can't use it, or maybe an SMP system
700 * using a pre-ARMv6 processor (there are apparently a few prototypes like
701 * that in existence) and therefore access to that register must be
702 * emulated.
703 */
704
705static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
706{
707	int reg = (instr >> 12) & 15;
708	if (reg == 15)
709		return 1;
710	regs->uregs[reg] = current_thread_info()->tp_value[0];
711	regs->ARM_pc += 4;
712	return 0;
713}
714
715static struct undef_hook arm_mrc_hook = {
716	.instr_mask	= 0x0fff0fff,
717	.instr_val	= 0x0e1d0f70,
718	.cpsr_mask	= PSR_T_BIT,
719	.cpsr_val	= 0,
720	.fn		= get_tp_trap,
721};
722
723static int __init arm_mrc_hook_init(void)
724{
725	register_undef_hook(&arm_mrc_hook);
726	return 0;
727}
728
729late_initcall(arm_mrc_hook_init);
730
731#endif
732
733/*
734 * A data abort trap was taken, but we did not handle the instruction.
735 * Try to abort the user program, or panic if it was the kernel.
736 */
737asmlinkage void
738baddataabort(int code, unsigned long instr, struct pt_regs *regs)
739{
740	unsigned long addr = instruction_pointer(regs);
741
742#ifdef CONFIG_DEBUG_USER
743	if (user_debug & UDBG_BADABORT) {
744		pr_err("8<--- cut here ---\n");
745		pr_err("[%d] %s: bad data abort: code %d instr 0x%08lx\n",
746		       task_pid_nr(current), current->comm, code, instr);
747		dump_instr(KERN_ERR, regs);
748		show_pte(KERN_ERR, current->mm, addr);
749	}
750#endif
751
752	arm_notify_die("unknown data abort code", regs,
753		       SIGILL, ILL_ILLOPC, (void __user *)addr, instr, 0);
754}
755
756void __readwrite_bug(const char *fn)
757{
758	pr_err("%s called, but not implemented\n", fn);
759	BUG();
760}
761EXPORT_SYMBOL(__readwrite_bug);
762
763#ifdef CONFIG_MMU
764void __pte_error(const char *file, int line, pte_t pte)
765{
766	pr_err("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
767}
768
769void __pmd_error(const char *file, int line, pmd_t pmd)
770{
771	pr_err("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
772}
773
774void __pgd_error(const char *file, int line, pgd_t pgd)
775{
776	pr_err("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
777}
778#endif
779
780asmlinkage void __div0(void)
781{
782	pr_err("Division by zero in kernel.\n");
783	dump_stack();
784}
785EXPORT_SYMBOL(__div0);
786
787void abort(void)
788{
789	BUG();
790
791	/* if that doesn't kill us, halt */
792	panic("Oops failed to kill thread");
793}
794
795#ifdef CONFIG_KUSER_HELPERS
796static void __init kuser_init(void *vectors)
797{
798	extern char __kuser_helper_start[], __kuser_helper_end[];
799	int kuser_sz = __kuser_helper_end - __kuser_helper_start;
800
801	memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
802
803	/*
804	 * vectors + 0xfe0 = __kuser_get_tls
805	 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
806	 */
807	if (tls_emu || has_tls_reg)
808		memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
809}
810#else
811static inline void __init kuser_init(void *vectors)
812{
813}
814#endif
815
816#ifndef CONFIG_CPU_V7M
817static void copy_from_lma(void *vma, void *lma_start, void *lma_end)
818{
819	memcpy(vma, lma_start, lma_end - lma_start);
820}
821
822static void flush_vectors(void *vma, size_t offset, size_t size)
823{
824	unsigned long start = (unsigned long)vma + offset;
825	unsigned long end = start + size;
826
827	flush_icache_range(start, end);
828}
829
830#ifdef CONFIG_HARDEN_BRANCH_HISTORY
831int spectre_bhb_update_vectors(unsigned int method)
832{
833	extern char __vectors_bhb_bpiall_start[], __vectors_bhb_bpiall_end[];
834	extern char __vectors_bhb_loop8_start[], __vectors_bhb_loop8_end[];
835	void *vec_start, *vec_end;
836
837	if (system_state >= SYSTEM_FREEING_INITMEM) {
838		pr_err("CPU%u: Spectre BHB workaround too late - system vulnerable\n",
839		       smp_processor_id());
840		return SPECTRE_VULNERABLE;
841	}
842
843	switch (method) {
844	case SPECTRE_V2_METHOD_LOOP8:
845		vec_start = __vectors_bhb_loop8_start;
846		vec_end = __vectors_bhb_loop8_end;
847		break;
848
849	case SPECTRE_V2_METHOD_BPIALL:
850		vec_start = __vectors_bhb_bpiall_start;
851		vec_end = __vectors_bhb_bpiall_end;
852		break;
853
854	default:
855		pr_err("CPU%u: unknown Spectre BHB state %d\n",
856		       smp_processor_id(), method);
857		return SPECTRE_VULNERABLE;
858	}
859
860	copy_from_lma(vectors_page, vec_start, vec_end);
861	flush_vectors(vectors_page, 0, vec_end - vec_start);
862
863	return SPECTRE_MITIGATED;
864}
865#endif
866
867void __init early_trap_init(void *vectors_base)
868{
869	extern char __stubs_start[], __stubs_end[];
870	extern char __vectors_start[], __vectors_end[];
871	unsigned i;
872
873	vectors_page = vectors_base;
874
875	/*
876	 * Poison the vectors page with an undefined instruction.  This
877	 * instruction is chosen to be undefined for both ARM and Thumb
878	 * ISAs.  The Thumb version is an undefined instruction with a
879	 * branch back to the undefined instruction.
880	 */
881	for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
882		((u32 *)vectors_base)[i] = 0xe7fddef1;
883
884	/*
885	 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
886	 * into the vector page, mapped at 0xffff0000, and ensure these
887	 * are visible to the instruction stream.
888	 */
889	copy_from_lma(vectors_base, __vectors_start, __vectors_end);
890	copy_from_lma(vectors_base + 0x1000, __stubs_start, __stubs_end);
891
892	kuser_init(vectors_base);
893
894	flush_vectors(vectors_base, 0, PAGE_SIZE * 2);
895}
896#else /* ifndef CONFIG_CPU_V7M */
897void __init early_trap_init(void *vectors_base)
898{
899	/*
900	 * on V7-M there is no need to copy the vector table to a dedicated
901	 * memory area. The address is configurable and so a table in the kernel
902	 * image can be used.
903	 */
904}
905#endif
906
907#ifdef CONFIG_VMAP_STACK
908
909DECLARE_PER_CPU(u8 *, irq_stack_ptr);
910
911asmlinkage DEFINE_PER_CPU(u8 *, overflow_stack_ptr);
912
913static int __init allocate_overflow_stacks(void)
914{
915	u8 *stack;
916	int cpu;
917
918	for_each_possible_cpu(cpu) {
919		stack = (u8 *)__get_free_page(GFP_KERNEL);
920		if (WARN_ON(!stack))
921			return -ENOMEM;
922		per_cpu(overflow_stack_ptr, cpu) = &stack[OVERFLOW_STACK_SIZE];
923	}
924	return 0;
925}
926early_initcall(allocate_overflow_stacks);
927
928asmlinkage void handle_bad_stack(struct pt_regs *regs)
929{
930	unsigned long tsk_stk = (unsigned long)current->stack;
931#ifdef CONFIG_IRQSTACKS
932	unsigned long irq_stk = (unsigned long)raw_cpu_read(irq_stack_ptr);
933#endif
934	unsigned long ovf_stk = (unsigned long)raw_cpu_read(overflow_stack_ptr);
935
936	console_verbose();
937	pr_emerg("Insufficient stack space to handle exception!");
938
939	pr_emerg("Task stack:     [0x%08lx..0x%08lx]\n",
940		 tsk_stk, tsk_stk + THREAD_SIZE);
941#ifdef CONFIG_IRQSTACKS
942	pr_emerg("IRQ stack:      [0x%08lx..0x%08lx]\n",
943		 irq_stk - THREAD_SIZE, irq_stk);
944#endif
945	pr_emerg("Overflow stack: [0x%08lx..0x%08lx]\n",
946		 ovf_stk - OVERFLOW_STACK_SIZE, ovf_stk);
947
948	die("kernel stack overflow", regs, 0);
949}
950
951#ifndef CONFIG_ARM_LPAE
952/*
953 * Normally, we rely on the logic in do_translation_fault() to update stale PMD
954 * entries covering the vmalloc space in a task's page tables when it first
955 * accesses the region in question. Unfortunately, this is not sufficient when
956 * the task stack resides in the vmalloc region, as do_translation_fault() is a
957 * C function that needs a stack to run.
958 *
959 * So we need to ensure that these PMD entries are up to date *before* the MM
960 * switch. As we already have some logic in the MM switch path that takes care
961 * of this, let's trigger it by bumping the counter every time the core vmalloc
962 * code modifies a PMD entry in the vmalloc region. Use release semantics on
963 * the store so that other CPUs observing the counter's new value are
964 * guaranteed to see the updated page table entries as well.
965 */
966void arch_sync_kernel_mappings(unsigned long start, unsigned long end)
967{
968	if (start < VMALLOC_END && end > VMALLOC_START)
969		atomic_inc_return_release(&init_mm.context.vmalloc_seq);
970}
971#endif
972#endif