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

/*
 *  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
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 *  '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/module.h>
#include <linux/kexec.h>
#include <linux/bug.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/sched.h>

#include <linux/atomic.h>
#include <asm/cacheflush.h>
#include <asm/exception.h>
#include <asm/unistd.h>
#include <asm/traps.h>
#include <asm/unwind.h>
#include <asm/tls.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

static void dump_mem(const char *, const char *, unsigned long, unsigned long);

void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
{
#ifdef CONFIG_KALLSYMS
	printk("[<%08lx>] (%ps) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
#else
	printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
#endif

	if (in_exception_text(where))
		dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
}

#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 ||
	    (sp > (unsigned long)high_memory && high_memory != NULL))
		return -EFAULT;

	return 0;
}
#endif

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

	/*
	 * We need to switch to kernel mode so that we can use __get_user
	 * to safely read from kernel space.  Note that we now dump the
	 * code first, just in case the backtrace kills us.
	 */
	fs = get_fs();
	set_fs(KERNEL_DS);

	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_user(val, (unsigned long *)p) == 0)
					sprintf(str + i * 9, " %08lx", val);
				else
					sprintf(str + i * 9, " ????????");
			}
		}
		printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
	}

	set_fs(fs);
}

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;
	mm_segment_t fs;
	char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
	int i;

	/*
	 * We need to switch to kernel mode so that we can use __get_user
	 * to safely read from kernel space.  Note that we now dump the
	 * code first, just in case the backtrace kills us.
	 */
	fs = get_fs();
	set_fs(KERNEL_DS);

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

		if (thumb)
			bad = __get_user(val, &((u16 *)addr)[i]);
		else
			bad = __get_user(val, &((u32 *)addr)[i]);

		if (!bad)
			p += sprintf(p, i ==