path: root/arch/arm/kernel/traps.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 *  linux/arch/arm/kernel/traps.c
 *
 *  Copyright (C) 1995-2009 Russell King
 *  Fragments that appear the same as linux/arch/i386/kernel/traps.c (C) Linus Torvalds
 *
 *  'traps.c' handles hardware exceptions after we have saved some state in
 *  'linux/arch/arm/lib/traps.S'.  Mostly a debugging aid, but will probably
 *  kill the offending process.
 */
#include <linux/signal.h>
#include <linux/personality.h>
#include <linux/kallsyms.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>
#include <linux/hardirq.h>
#include <linux/kdebug.h>
#include <linux/kprobes.h>
#include <linux/module.h>
#include <linux/kexec.h>
#include <linux/bug.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/sched/signal.h>
#include <linux/sched/debug.h>
#include <linux/sched/task_stack.h>
#include <linux/irq.h>

#include <linux/atomic.h>
#include <asm/cacheflush.h>
#include <asm/exception.h>
#include <asm/spectre.h>
#include <asm/unistd.h>
#include <asm/traps.h>
#include <asm/ptrace.h>
#include <asm/unwind.h>
#include <asm/tls.h>
#include <asm/stacktrace.h>
#include <asm/system_misc.h>
#include <asm/opcodes.h>


static const char *handler[]= {
	"prefetch abort",
	"data abort",
	"address exception",
	"interrupt",
	"undefined instruction",
};

void *vectors_page;

#ifdef CONFIG_DEBUG_USER
unsigned int user_debug;

static int __init user_debug_setup(char *str)
{
	get_option(&str, &user_debug);
	return 1;
}
__setup("user_debug=", user_debug_setup);
#endif

void dump_backtrace_entry(unsigned long where, unsigned long from,
			  unsigned long frame, const char *loglvl)
{
	unsigned long end = frame + 4 + sizeof(struct pt_regs);

	if (IS_ENABLED(CONFIG_UNWINDER_FRAME_POINTER) &&
	    IS_ENABLED(CONFIG_CC_IS_GCC) &&
	    end > ALIGN(frame, THREAD_SIZE)) {
		/*
		 * If we are walking past the end of the stack, it may be due
		 * to the fact that we are on an IRQ or overflow stack. In this
		 * case, we can load the address of the other stack from the
		 * frame record.
		 */
		frame = ((unsigned long *)frame)[-2] - 4;
		end = frame + 4 + sizeof(struct pt_regs);
	}

#ifndef CONFIG_KALLSYMS
	printk("%sFunction entered at [<%08lx>] from [<%08lx>]\n",
		loglvl, where, from);
#elif defined CONFIG_BACKTRACE_VERBOSE
	printk("%s[<%08lx>] (%ps) from [<%08lx>] (%pS)\n",
		loglvl, where, (void *)where, from, (void *)from);
#else
	printk("%s %ps from %pS\n", loglvl, (void *)where, (void *)from);
#endif

	if (in_entry_text(from) && end <= ALIGN(frame, THREAD_SIZE))
		dump_mem(loglvl, "Exception stack", frame + 4, end);
}

void dump_backtrace_stm(u32 *stack, u32 instruction, const char *loglvl)
{
	char str[80], *p;
	unsigned int x;
	int reg;

	for (reg = 10, x = 0, p = str; reg >= 0; reg--) {
		if (instruction & BIT(reg)) {
			p += sprintf(p, " r%d:%08x", reg, *stack--);
			if (++x == 6) {
				x = 0;
				p = str;
				printk("%s%s\n", loglvl, str);
			}
		}
	}
	if (p != str)
		printk("%s%s\n", loglvl, str);
}

#ifndef CONFIG_ARM_UNWIND
/*
 * Stack pointers should always be within the kernels view of
 * physical memory.  If it is not there, then we can't dump
 * out any information relating to the stack.
 */
static int verify_stack(unsigned long sp)
{
	if (sp < PAGE_OFFSET ||
	    (!IS_ENABLED(CONFIG_VMAP_STACK) &&
	     sp > (unsigned long)high_memory && high_memory != NULL))
		return -EFAULT;

	return 0;
}
#endif

/*
 * Dump out the contents of some memory nicely...
 */
void dump_mem(const char *lvl, const char *str, unsigned long bottom,
	      unsigned long top)
{
	unsigned long first;
	int i;

	printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);

	for (first = bottom & ~31; first < top; first += 32) {
		unsigned long p;
		char str[sizeof(" 12345678") * 8 + 1];

		memset(str, ' ', sizeof(str));
		str[sizeof(str) - 1] = '\0';

		for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
			if (p >= bottom && p < top) {
				unsigned long val;
				if (!get_kernel_nofault(val, (unsigned long *)p))
					sprintf(str + i * 9, " %08lx", val);
				else
					sprintf(str + i * 9, " ????????");
			}
		}
		printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
	}
}

static void dump_instr(const char *lvl, struct pt_regs *regs)
{
	unsigned long addr = instruction_pointer(regs);
	const int thumb = thumb_mode(regs);
	const int width = thumb ? 4 : 8;
	char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
	int i;

	/*
	 * Note that we now dump the code first, just in case the backtrace
	 * kills us.
	 */

	for (i = -4; i < 1 + !!thumb; i++) {
		unsigned int val, bad;

		if (thumb) {
			u16 tmp;

			if (user_mode