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
 30#include <linux/atomic.h>
 31#include <asm/cacheflush.h>
 32#include <asm/exception.h>
 33#include <asm/spectre.h>
 34#include <asm/unistd.h>
 35#include <asm/traps.h>
 36#include <asm/ptrace.h>
 37#include <asm/unwind.h>
 38#include <asm/tls.h>
 39#include <asm/stacktrace.h>
 40#include <asm/system_misc.h>
 41#include <asm/opcodes.h>
 42
 43
 44static const char *handler[]= {
 45	"prefetch abort",
 46	"data abort",
 47	"address exception",
 48	"interrupt",
 49	"undefined instruction",
 50};
 51
 52void *vectors_page;
 53
 54#ifdef CONFIG_DEBUG_USER
 55unsigned int user_debug;
 56
 57static int __init user_debug_setup(char *str)
 58{
 59	get_option(&str, &user_debug);
 60	return 1;
 61}
 62__setup("user_debug=", user_debug_setup);
 63#endif
 64
 
 
 65void dump_backtrace_entry(unsigned long where, unsigned long from,
 66			  unsigned long frame, const char *loglvl)
 67{
 68	unsigned long end = frame + 4 + sizeof(struct pt_regs);
 69
 70	if (IS_ENABLED(CONFIG_UNWINDER_FRAME_POINTER) &&
 71	    IS_ENABLED(CONFIG_CC_IS_GCC) &&
 72	    end > ALIGN(frame, THREAD_SIZE)) {
 73		/*
 74		 * If we are walking past the end of the stack, it may be due
 75		 * to the fact that we are on an IRQ or overflow stack. In this
 76		 * case, we can load the address of the other stack from the
 77		 * frame record.
 78		 */
 79		frame = ((unsigned long *)frame)[-2] - 4;
 80		end = frame + 4 + sizeof(struct pt_regs);
 81	}
 82
 83#ifndef CONFIG_KALLSYMS
 84	printk("%sFunction entered at [<%08lx>] from [<%08lx>]\n",
 85		loglvl, where, from);
 86#elif defined CONFIG_BACKTRACE_VERBOSE
 87	printk("%s[<%08lx>] (%ps) from [<%08lx>] (%pS)\n",
 88		loglvl, where, (void *)where, from, (void *)from);
 89#else
 90	printk("%s %ps from %pS\n", loglvl, (void *)where, (void *)from);
 
 91#endif
 92
 93	if (in_entry_text(from) && end <= ALIGN(frame, THREAD_SIZE))
 94		dump_mem(loglvl, "Exception stack", frame + 4, end);
 95}
 96
 97void dump_backtrace_stm(u32 *stack, u32 instruction, const char *loglvl)
 98{
 99	char str[80], *p;
100	unsigned int x;
101	int reg;
102
103	for (reg = 10, x = 0, p = str; reg >= 0; reg--) {
104		if (instruction & BIT(reg)) {
105			p += sprintf(p, " r%d:%08x", reg, *stack--);
106			if (++x == 6) {
107				x = 0;
108				p = str;
109				printk("%s%s\n", loglvl, str);
110			}
111		}
112	}
113	if (p != str)
114		printk("%s%s\n", loglvl, str);
115}
116
117#ifndef CONFIG_ARM_UNWIND
118/*
119 * Stack pointers should always be within the kernels view of
120 * physical memory.  If it is not there, then we can't dump
121 * out any information relating to the stack.
122 */
123static int verify_stack(unsigned long sp)
124{
125	if (sp < PAGE_OFFSET ||
126	    (!IS_ENABLED(CONFIG_VMAP_STACK) &&
127	     sp > (unsigned long)high_memory && high_memory != NULL))
128		return -EFAULT;
129
130	return 0;
131}
132#endif
133
134/*
135 * Dump out the contents of some memory nicely...
136 */
137void dump_mem(const char *lvl, const char *str, unsigned long bottom,
138	      unsigned long top)
139{
140	unsigned long first;
 
141	int i;
142
 
 
 
 
 
 
 
 
143	printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
144
145	for (first = bottom & ~31; first < top; first += 32) {
146		unsigned long p;
147		char str[sizeof(" 12345678") * 8 + 1];
148
149		memset(str, ' ', sizeof(str));
150		str[sizeof(str) - 1] = '\0';
151
152		for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
153			if (p >= bottom && p < top) {
154				unsigned long val;
155				if (!get_kernel_nofault(val, (unsigned long *)p))
156					sprintf(str + i * 9, " %08lx", val);
157				else
158					sprintf(str + i * 9, " ????????");
159			}
160		}
161		printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
162	}
 
 
163}
164
165static void dump_instr(const char *lvl, struct pt_regs *regs)
166{
167	unsigned long addr = instruction_pointer(regs);
168	const int thumb = thumb_mode(regs);
169	const int width = thumb ? 4 : 8;
170	char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
171	int i;
172
173	/*
174	 * Note that we now dump the code first, just in case the backtrace
175	 * kills us.
176	 */
177
178	for (i = -4; i < 1 + !!thumb; i++) {
179		unsigned int val, bad;
180
181		if (thumb) {
182			u16 tmp;
183
184			if (user_mode(regs))
185				bad = get_user(tmp, &((u16 __user *)addr)[i]);
186			else
187				bad = get_kernel_nofault(tmp, &((u16 *)addr)[i]);
188
189			val = __mem_to_opcode_thumb16(tmp);
190		} else {
191			if (user_mode(regs))
192				bad = get_user(val, &((u32 __user *)addr)[i]);
193			else
194				bad = get_kernel_nofault(val, &((u32 *)addr)[i]);
195
196			val = __mem_to_opcode_arm(val);
197		}
198
199		if (!bad)
200			p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
201					width, val);
202		else {
203			p += sprintf(p, "bad PC value");
204			break;
205		}
206	}
207	printk("%sCode: %s\n", lvl, str);
208}
209
 
 
 
 
 
 
 
 
 
 
 
 
 
 
210#ifdef CONFIG_ARM_UNWIND
211void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
212		    const char *loglvl)
213{
214	unwind_backtrace(regs, tsk, loglvl);
215}
216#else
217void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
218		    const char *loglvl)
219{
220	unsigned int fp, mode;
221	int ok = 1;
222
223	printk("%sBacktrace: ", loglvl);
224
225	if (!tsk)
226		tsk = current;
227
228	if (regs) {
229		fp = frame_pointer(regs);
230		mode = processor_mode(regs);
231	} else if (tsk != current) {
232		fp = thread_saved_fp(tsk);
233		mode = 0x10;
234	} else {
235		asm("mov %0, fp" : "=r" (fp) : : "cc");
236		mode = 0x10;
237	}
238
239	if (!fp) {
240		pr_cont("no frame pointer");
241		ok = 0;
242	} else if (verify_stack(fp)) {
243		pr_cont("invalid frame pointer 0x%08x", fp);
244		ok = 0;
245	} else if (fp < (unsigned long)end_of_stack(tsk))
246		pr_cont("frame pointer underflow");
247	pr_cont("\n");
248
249	if (ok)
250		c_backtrace(fp, mode, loglvl);
251}
252#endif
253
254void show_stack(struct task_struct *tsk, unsigned long *sp, const char *loglvl)
255{
256	dump_backtrace(NULL, tsk, loglvl);
257	barrier();
258}
259
260#ifdef CONFIG_PREEMPT
261#define S_PREEMPT " PREEMPT"
262#elif defined(CONFIG_PREEMPT_RT)
263#define S_PREEMPT " PREEMPT_RT"
264#else
265#define S_PREEMPT ""
266#endif
267#ifdef CONFIG_SMP
268#define S_SMP " SMP"
269#else
270#define S_SMP ""
271#endif
272#ifdef CONFIG_THUMB2_KERNEL
273#define S_ISA " THUMB2"
274#else
275#define S_ISA " ARM"
276#endif
277
278static int __die(const char *str, int err, struct pt_regs *regs)
279{
280	struct task_struct *tsk = current;
281	static int die_counter;
282	int ret;
283
284	pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP S_ISA "\n",
285	         str, err, ++die_counter);
286
287	/* trap and error numbers are mostly meaningless on ARM */
288	ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
289	if (ret == NOTIFY_STOP)
290		return 1;
291
292	print_modules();
293	__show_regs(regs);
294	__show_regs_alloc_free(regs);
295	pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
296		 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
297
298	if (!user_mode(regs) || in_interrupt()) {
299		dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
300			 ALIGN(regs->ARM_sp - THREAD_SIZE, THREAD_ALIGN)
301			 + THREAD_SIZE);
302		dump_backtrace(regs, tsk, KERN_EMERG);
303		dump_instr(KERN_EMERG, regs);
304	}
305
306	return 0;
307}
308
309static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
310static int die_owner = -1;
311static unsigned int die_nest_count;
312
313static unsigned long oops_begin(void)
314{
315	int cpu;
316	unsigned long flags;
317
318	oops_enter();
319
320	/* racy, but better than risking deadlock. */
321	raw_local_irq_save(flags);
322	cpu = smp_processor_id();
323	if (!arch_spin_trylock(&die_lock)) {
324		if (cpu == die_owner)
325			/* nested oops. should stop eventually */;
326		else
327			arch_spin_lock(&die_lock);
328	}
329	die_nest_count++;
330	die_owner = cpu;
331	console_verbose();
332	bust_spinlocks(1);
333	return flags;
334}
335
336static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
337{
338	if (regs && kexec_should_crash(current))
339		crash_kexec(regs);
340
341	bust_spinlocks(0);
342	die_owner = -1;
343	add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
344	die_nest_count--;
345	if (!die_nest_count)
346		/* Nest count reaches zero, release the lock. */
347		arch_spin_unlock(&die_lock);
348	raw_local_irq_restore(flags);
349	oops_exit();
350
351	if (in_interrupt())
352		panic("Fatal exception in interrupt");
353	if (panic_on_oops)
354		panic("Fatal exception");
355	if (signr)
356		make_task_dead(signr);
357}
358
359/*
360 * This function is protected against re-entrancy.
361 */
362void die(const char *str, struct pt_regs *regs, int err)
363{
364	enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
365	unsigned long flags = oops_begin();
366	int sig = SIGSEGV;
367
368	if (!user_mode(regs))
369		bug_type = report_bug(regs->ARM_pc, regs);
370	if (bug_type != BUG_TRAP_TYPE_NONE)
371		str = "Oops - BUG";
372
373	if (__die(str, err, regs))
374		sig = 0;
375
376	oops_end(flags, regs, sig);
377}
378
379void arm_notify_die(const char *str, struct pt_regs *regs,
380		int signo, int si_code, void __user *addr,
381		unsigned long err, unsigned long trap)
382{
383	if (user_mode(regs)) {
384		current->thread.error_code = err;
385		current->thread.trap_no = trap;
386
387		force_sig_fault(signo, si_code, addr);
388	} else {
389		die(str, regs, err);
390	}
391}
392
393#ifdef CONFIG_GENERIC_BUG
394
395int is_valid_bugaddr(unsigned long pc)
396{
397#ifdef CONFIG_THUMB2_KERNEL
398	u16 bkpt;
399	u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);
400#else
401	u32 bkpt;
402	u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
403#endif
404
405	if (get_kernel_nofault(bkpt, (void *)pc))
406		return 0;
407
408	return bkpt == insn;
409}
410
411#endif
412
413static LIST_HEAD(undef_hook);
414static DEFINE_RAW_SPINLOCK(undef_lock);
415
416void register_undef_hook(struct undef_hook *hook)
417{
418	unsigned long flags;
419
420	raw_spin_lock_irqsave(&undef_lock, flags);
421	list_add(&hook->node, &undef_hook);
422	raw_spin_unlock_irqrestore(&undef_lock, flags);
423}
424
425void unregister_undef_hook(struct undef_hook *hook)
426{
427	unsigned long flags;
428
429	raw_spin_lock_irqsave(&undef_lock, flags);
430	list_del(&hook->node);
431	raw_spin_unlock_irqrestore(&undef_lock, flags);
432}
433
434static nokprobe_inline
435int call_undef_hook(struct pt_regs *regs, unsigned int instr)
436{
437	struct undef_hook *hook;
438	unsigned long flags;
439	int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
440
441	raw_spin_lock_irqsave(&undef_lock, flags);
442	list_for_each_entry(hook, &undef_hook, node)
443		if ((instr & hook->instr_mask) == hook->instr_val &&
444		    (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
445			fn = hook->fn;
446	raw_spin_unlock_irqrestore(&undef_lock, flags);
447
448	return fn ? fn(regs, instr) : 1;
449}
450
451asmlinkage void do_undefinstr(struct pt_regs *regs)
452{
453	unsigned int instr;
454	void __user *pc;
455
456	pc = (void __user *)instruction_pointer(regs);
457
458	if (processor_mode(regs) == SVC_MODE) {
459#ifdef CONFIG_THUMB2_KERNEL
460		if (thumb_mode(regs)) {
461			instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
462			if (is_wide_instruction(instr)) {
463				u16 inst2;
464				inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
465				instr = __opcode_thumb32_compose(instr, inst2);
466			}
467		} else
468#endif
469			instr = __mem_to_opcode_arm(*(u32 *) pc);
470	} else if (thumb_mode(regs)) {
471		if (get_user(instr, (u16 __user *)pc))
472			goto die_sig;
473		instr = __mem_to_opcode_thumb16(instr);
474		if (is_wide_instruction(instr)) {
475			unsigned int instr2;
476			if (get_user(instr2, (u16 __user *)pc+1))
477				goto die_sig;
478			instr2 = __mem_to_opcode_thumb16(instr2);
479			instr = __opcode_thumb32_compose(instr, instr2);
480		}
481	} else {
482		if (get_user(instr, (u32 __user *)pc))
483			goto die_sig;
484		instr = __mem_to_opcode_arm(instr);
485	}
486
487	if (call_undef_hook(regs, instr) == 0)
488		return;
489
490die_sig:
491#ifdef CONFIG_DEBUG_USER
492	if (user_debug & UDBG_UNDEFINED) {
493		pr_info("%s (%d): undefined instruction: pc=%px\n",
494			current->comm, task_pid_nr(current), pc);
495		__show_regs(regs);
496		dump_instr(KERN_INFO, regs);
497	}
498#endif
499	arm_notify_die("Oops - undefined instruction", regs,
500		       SIGILL, ILL_ILLOPC, pc, 0, 6);
501}
502NOKPROBE_SYMBOL(do_undefinstr)
503
504/*
505 * Handle FIQ similarly to NMI on x86 systems.
506 *
507 * The runtime environment for NMIs is extremely restrictive
508 * (NMIs can pre-empt critical sections meaning almost all locking is
509 * forbidden) meaning this default FIQ handling must only be used in
510 * circumstances where non-maskability improves robustness, such as
511 * watchdog or debug logic.
512 *
513 * This handler is not appropriate for general purpose use in drivers
514 * platform code and can be overrideen using set_fiq_handler.
515 */
516asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs)
517{
518	struct pt_regs *old_regs = set_irq_regs(regs);
519
520	nmi_enter();
521
522	/* nop. FIQ handlers for special arch/arm features can be added here. */
523
524	nmi_exit();
525
526	set_irq_regs(old_regs);
527}
528
529/*
530 * bad_mode handles the impossible case in the vectors.  If you see one of
531 * these, then it's extremely serious, and could mean you have buggy hardware.
532 * It never returns, and never tries to sync.  We hope that we can at least
533 * dump out some state information...
534 */
535asmlinkage void bad_mode(struct pt_regs *regs, int reason)
536{
537	console_verbose();
538
539	pr_crit("Bad mode in %s handler detected\n", handler[reason]);
540
541	die("Oops - bad mode", regs, 0);
542	local_irq_disable();
543	panic("bad mode");
544}
545
546static int bad_syscall(int n, struct pt_regs *regs)
547{
548	if ((current->personality & PER_MASK) != PER_LINUX) {
549		send_sig(SIGSEGV, current, 1);
550		return regs->ARM_r0;
551	}
552
553#ifdef CONFIG_DEBUG_USER
554	if (user_debug & UDBG_SYSCALL) {
555		pr_err("[%d] %s: obsolete system call %08x.\n",
556			task_pid_nr(current), current->comm, n);
557		dump_instr(KERN_ERR, regs);
558	}
559#endif
560
561	arm_notify_die("Oops - bad syscall", regs, SIGILL, ILL_ILLTRP,
562		       (void __user *)instruction_pointer(regs) -
563			 (thumb_mode(regs) ? 2 : 4),
564		       n, 0);
565
566	return regs->ARM_r0;
567}
568
569static inline int
570__do_cache_op(unsigned long start, unsigned long end)
571{
572	int ret;
573
574	do {
575		unsigned long chunk = min(PAGE_SIZE, end - start);
576
577		if (fatal_signal_pending(current))
578			return 0;
579
580		ret = flush_icache_user_range(start, start + chunk);
581		if (ret)
582			return ret;
583
584		cond_resched();
585		start += chunk;
586	} while (start < end);
587
588	return 0;
589}
590
591static inline int
592do_cache_op(unsigned long start, unsigned long end, int flags)
593{
594	if (end < start || flags)
595		return -EINVAL;
596
597	if (!access_ok((void __user *)start, end - start))
598		return -EFAULT;
599
600	return __do_cache_op(start, end);
601}
602
603/*
604 * Handle all unrecognised system calls.
605 *  0x9f0000 - 0x9fffff are some more esoteric system calls
606 */
607#define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
608asmlinkage int arm_syscall(int no, struct pt_regs *regs)
609{
610	if ((no >> 16) != (__ARM_NR_BASE>> 16))
611		return bad_syscall(no, regs);
612
613	switch (no & 0xffff) {
614	case 0: /* branch through 0 */
615		arm_notify_die("branch through zero", regs,
616			       SIGSEGV, SEGV_MAPERR, NULL, 0, 0);
617		return 0;
618
619	case NR(breakpoint): /* SWI BREAK_POINT */
620		regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
621		ptrace_break(regs);
622		return regs->ARM_r0;
623
624	/*
625	 * Flush a region from virtual address 'r0' to virtual address 'r1'
626	 * _exclusive_.  There is no alignment requirement on either address;
627	 * user space does not need to know the hardware cache layout.
628	 *
629	 * r2 contains flags.  It should ALWAYS be passed as ZERO until it
630	 * is defined to be something else.  For now we ignore it, but may
631	 * the fires of hell burn in your belly if you break this rule. ;)
632	 *
633	 * (at a later date, we may want to allow this call to not flush
634	 * various aspects of the cache.  Passing '0' will guarantee that
635	 * everything necessary gets flushed to maintain consistency in
636	 * the specified region).
637	 */
638	case NR(cacheflush):
639		return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
640
641	case NR(usr26):
642		if (!(elf_hwcap & HWCAP_26BIT))
643			break;
644		regs->ARM_cpsr &= ~MODE32_BIT;
645		return regs->ARM_r0;
646
647	case NR(usr32):
648		if (!(elf_hwcap & HWCAP_26BIT))
649			break;
650		regs->ARM_cpsr |= MODE32_BIT;
651		return regs->ARM_r0;
652
653	case NR(set_tls):
654		set_tls(regs->ARM_r0);
655		return 0;
656
657	case NR(get_tls):
658		return current_thread_info()->tp_value[0];
659
660	default:
661		/* Calls 9f00xx..9f07ff are defined to return -ENOSYS
662		   if not implemented, rather than raising SIGILL.  This
663		   way the calling program can gracefully determine whether
664		   a feature is supported.  */
665		if ((no & 0xffff) <= 0x7ff)
666			return -ENOSYS;
667		break;
668	}
669#ifdef CONFIG_DEBUG_USER
670	/*
671	 * experience shows that these seem to indicate that
672	 * something catastrophic has happened
673	 */
674	if (user_debug & UDBG_SYSCALL) {
675		pr_err("[%d] %s: arm syscall %d\n",
676		       task_pid_nr(current), current->comm, no);
677		dump_instr(KERN_ERR, regs);
678		if (user_mode(regs)) {
679			__show_regs(regs);
680			c_backtrace(frame_pointer(regs), processor_mode(regs), KERN_ERR);
681		}
682	}
683#endif
684	arm_notify_die("Oops - bad syscall(2)", regs, SIGILL, ILL_ILLTRP,
685		       (void __user *)instruction_pointer(regs) -
686			 (thumb_mode(regs) ? 2 : 4),
687		       no, 0);
688	return 0;
689}
690
691#ifdef CONFIG_TLS_REG_EMUL
692
693/*
694 * We might be running on an ARMv6+ processor which should have the TLS
695 * register but for some reason we can't use it, or maybe an SMP system
696 * using a pre-ARMv6 processor (there are apparently a few prototypes like
697 * that in existence) and therefore access to that register must be
698 * emulated.
699 */
700
701static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
702{
703	int reg = (instr >> 12) & 15;
704	if (reg == 15)
705		return 1;
706	regs->uregs[reg] = current_thread_info()->tp_value[0];
707	regs->ARM_pc += 4;
708	return 0;
709}
710
711static struct undef_hook arm_mrc_hook = {
712	.instr_mask	= 0x0fff0fff,
713	.instr_val	= 0x0e1d0f70,
714	.cpsr_mask	= PSR_T_BIT,
715	.cpsr_val	= 0,
716	.fn		= get_tp_trap,
717};
718
719static int __init arm_mrc_hook_init(void)
720{
721	register_undef_hook(&arm_mrc_hook);
722	return 0;
723}
724
725late_initcall(arm_mrc_hook_init);
726
727#endif
728
729/*
730 * A data abort trap was taken, but we did not handle the instruction.
731 * Try to abort the user program, or panic if it was the kernel.
732 */
733asmlinkage void
734baddataabort(int code, unsigned long instr, struct pt_regs *regs)
735{
736	unsigned long addr = instruction_pointer(regs);
737
738#ifdef CONFIG_DEBUG_USER
739	if (user_debug & UDBG_BADABORT) {
740		pr_err("8<--- cut here ---\n");
741		pr_err("[%d] %s: bad data abort: code %d instr 0x%08lx\n",
742		       task_pid_nr(current), current->comm, code, instr);
743		dump_instr(KERN_ERR, regs);
744		show_pte(KERN_ERR, current->mm, addr);
745	}
746#endif
747
748	arm_notify_die("unknown data abort code", regs,
749		       SIGILL, ILL_ILLOPC, (void __user *)addr, instr, 0);
750}
751
752void __readwrite_bug(const char *fn)
753{
754	pr_err("%s called, but not implemented\n", fn);
755	BUG();
756}
757EXPORT_SYMBOL(__readwrite_bug);
758
759#ifdef CONFIG_MMU
760void __pte_error(const char *file, int line, pte_t pte)
761{
762	pr_err("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
763}
764
765void __pmd_error(const char *file, int line, pmd_t pmd)
766{
767	pr_err("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
768}
769
770void __pgd_error(const char *file, int line, pgd_t pgd)
771{
772	pr_err("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
773}
774#endif
775
776asmlinkage void __div0(void)
777{
778	pr_err("Division by zero in kernel.\n");
779	dump_stack();
780}
781EXPORT_SYMBOL(__div0);
782
783void abort(void)
784{
785	BUG();
786
787	/* if that doesn't kill us, halt */
788	panic("Oops failed to kill thread");
789}
790
 
 
 
 
 
791#ifdef CONFIG_KUSER_HELPERS
792static void __init kuser_init(void *vectors)
793{
794	extern char __kuser_helper_start[], __kuser_helper_end[];
795	int kuser_sz = __kuser_helper_end - __kuser_helper_start;
796
797	memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
798
799	/*
800	 * vectors + 0xfe0 = __kuser_get_tls
801	 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
802	 */
803	if (tls_emu || has_tls_reg)
804		memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
805}
806#else
807static inline void __init kuser_init(void *vectors)
808{
809}
810#endif
811
812#ifndef CONFIG_CPU_V7M
813static void copy_from_lma(void *vma, void *lma_start, void *lma_end)
814{
815	memcpy(vma, lma_start, lma_end - lma_start);
816}
817
818static void flush_vectors(void *vma, size_t offset, size_t size)
819{
820	unsigned long start = (unsigned long)vma + offset;
821	unsigned long end = start + size;
822
823	flush_icache_range(start, end);
824}
825
826#ifdef CONFIG_HARDEN_BRANCH_HISTORY
827int spectre_bhb_update_vectors(unsigned int method)
828{
829	extern char __vectors_bhb_bpiall_start[], __vectors_bhb_bpiall_end[];
830	extern char __vectors_bhb_loop8_start[], __vectors_bhb_loop8_end[];
831	void *vec_start, *vec_end;
832
833	if (system_state >= SYSTEM_FREEING_INITMEM) {
834		pr_err("CPU%u: Spectre BHB workaround too late - system vulnerable\n",
835		       smp_processor_id());
836		return SPECTRE_VULNERABLE;
837	}
838
839	switch (method) {
840	case SPECTRE_V2_METHOD_LOOP8:
841		vec_start = __vectors_bhb_loop8_start;
842		vec_end = __vectors_bhb_loop8_end;
843		break;
844
845	case SPECTRE_V2_METHOD_BPIALL:
846		vec_start = __vectors_bhb_bpiall_start;
847		vec_end = __vectors_bhb_bpiall_end;
848		break;
849
850	default:
851		pr_err("CPU%u: unknown Spectre BHB state %d\n",
852		       smp_processor_id(), method);
853		return SPECTRE_VULNERABLE;
854	}
855
856	copy_from_lma(vectors_page, vec_start, vec_end);
857	flush_vectors(vectors_page, 0, vec_end - vec_start);
858
859	return SPECTRE_MITIGATED;
860}
861#endif
862
863void __init early_trap_init(void *vectors_base)
864{
 
 
865	extern char __stubs_start[], __stubs_end[];
866	extern char __vectors_start[], __vectors_end[];
867	unsigned i;
868
869	vectors_page = vectors_base;
870
871	/*
872	 * Poison the vectors page with an undefined instruction.  This
873	 * instruction is chosen to be undefined for both ARM and Thumb
874	 * ISAs.  The Thumb version is an undefined instruction with a
875	 * branch back to the undefined instruction.
876	 */
877	for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
878		((u32 *)vectors_base)[i] = 0xe7fddef1;
879
880	/*
881	 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
882	 * into the vector page, mapped at 0xffff0000, and ensure these
883	 * are visible to the instruction stream.
884	 */
885	copy_from_lma(vectors_base, __vectors_start, __vectors_end);
886	copy_from_lma(vectors_base + 0x1000, __stubs_start, __stubs_end);
887
888	kuser_init(vectors_base);
889
890	flush_vectors(vectors_base, 0, PAGE_SIZE * 2);
891}
892#else /* ifndef CONFIG_CPU_V7M */
893void __init early_trap_init(void *vectors_base)
894{
895	/*
896	 * on V7-M there is no need to copy the vector table to a dedicated
897	 * memory area. The address is configurable and so a table in the kernel
898	 * image can be used.
899	 */
900}
901#endif
902
903#ifdef CONFIG_VMAP_STACK
904
905DECLARE_PER_CPU(u8 *, irq_stack_ptr);
906
907asmlinkage DEFINE_PER_CPU(u8 *, overflow_stack_ptr);
908
909static int __init allocate_overflow_stacks(void)
910{
911	u8 *stack;
912	int cpu;
913
914	for_each_possible_cpu(cpu) {
915		stack = (u8 *)__get_free_page(GFP_KERNEL);
916		if (WARN_ON(!stack))
917			return -ENOMEM;
918		per_cpu(overflow_stack_ptr, cpu) = &stack[OVERFLOW_STACK_SIZE];
919	}
920	return 0;
921}
922early_initcall(allocate_overflow_stacks);
923
924asmlinkage void handle_bad_stack(struct pt_regs *regs)
925{
926	unsigned long tsk_stk = (unsigned long)current->stack;
927#ifdef CONFIG_IRQSTACKS
928	unsigned long irq_stk = (unsigned long)raw_cpu_read(irq_stack_ptr);
929#endif
930	unsigned long ovf_stk = (unsigned long)raw_cpu_read(overflow_stack_ptr);
931
932	console_verbose();
933	pr_emerg("Insufficient stack space to handle exception!");
934
935	pr_emerg("Task stack:     [0x%08lx..0x%08lx]\n",
936		 tsk_stk, tsk_stk + THREAD_SIZE);
937#ifdef CONFIG_IRQSTACKS
938	pr_emerg("IRQ stack:      [0x%08lx..0x%08lx]\n",
939		 irq_stk - THREAD_SIZE, irq_stk);
940#endif
941	pr_emerg("Overflow stack: [0x%08lx..0x%08lx]\n",
942		 ovf_stk - OVERFLOW_STACK_SIZE, ovf_stk);
943
944	die("kernel stack overflow", regs, 0);
945}
946
947#ifndef CONFIG_ARM_LPAE
948/*
949 * Normally, we rely on the logic in do_translation_fault() to update stale PMD
950 * entries covering the vmalloc space in a task's page tables when it first
951 * accesses the region in question. Unfortunately, this is not sufficient when
952 * the task stack resides in the vmalloc region, as do_translation_fault() is a
953 * C function that needs a stack to run.
954 *
955 * So we need to ensure that these PMD entries are up to date *before* the MM
956 * switch. As we already have some logic in the MM switch path that takes care
957 * of this, let's trigger it by bumping the counter every time the core vmalloc
958 * code modifies a PMD entry in the vmalloc region. Use release semantics on
959 * the store so that other CPUs observing the counter's new value are
960 * guaranteed to see the updated page table entries as well.
961 */
962void arch_sync_kernel_mappings(unsigned long start, unsigned long end)
963{
964	if (start < VMALLOC_END && end > VMALLOC_START)
965		atomic_inc_return_release(&init_mm.context.vmalloc_seq);
966}
967#endif
968#endif