traps.c

linux 内核源代码

/*
 *  linux/arch/arm/kernel/traps.c
 *
 *  Copyright (C) 1995-2002 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/module.h>
#include <linux/signal.h>
#include <linux/spinlock.h>
#include <linux/personality.h>
#include <linux/kallsyms.h>
#include <linux/delay.h>
#include <linux/init.h>

#include <asm/atomic.h>
#include <asm/cacheflush.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>
#include <asm/traps.h>
#include <asm/io.h>

#include "ptrace.h"
#include "signal.h"

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

#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 *str, unsigned long bottom, unsigned long top);

static inline int in_exception_text(unsigned long ptr)
{
	extern char __exception_text_start[];
	extern char __exception_text_end[];

	return ptr >= (unsigned long)&__exception_text_start &&
	       ptr < (unsigned long)&__exception_text_end;
}

void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
{
#ifdef CONFIG_KALLSYMS
	printk("[<%08lx>] ", where);
	print_symbol("(%s) ", where);
	printk("from [<%08lx>] ", from);
	print_symbol("(%s)\n", 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));
}

/*
 * 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 != 0))
		return -EFAULT;

	return 0;
}

/*
 * Dump out the contents of some memory nicely...
 */
static void dump_mem(const char *str, unsigned long bottom, unsigned long top)
{
	unsigned long p = bottom & ~31;
	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(0x%08lx to 0x%08lx)\n", str, bottom, top);

	for (p = bottom & ~31; p < top;) {
		printk("%04lx: ", p & 0xffff);

		for (i = 0; i < 8; i++, p += 4) {
			unsigned int val;

			if (p < bottom || p >= top)
				printk("         ");
			else {
				__get_user(val, (unsigned long *)p);
				printk("%08x ", val);
			}
		}
		printk ("\n");
	}

	set_fs(fs);
}

static void dump_instr(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;
	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("Code: ");
	for (i = -4; i < 1; i++) {
		unsigned int val, bad;

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

		if (!bad)
			printk(i == 0 ? "(%0*x) " : "%0*x ", width, val);
		else {
			printk("bad PC value.");
			break;
		}
	}
	printk("\n");

	set_fs(fs);
}

static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
{
	unsigned int fp;
	int ok = 1;

	printk("Backtrace: ");
	fp = regs->ARM_fp;
	if (!fp) {
		printk("no frame pointer");
		ok = 0;
	} else if (verify_stack(fp)) {
		printk("invalid frame pointer 0x%08x", fp);
		ok = 0;
	} else if (fp < (unsigned long)end_of_stack(tsk))
		printk("frame pointer underflow");
	printk("\n");

	if (ok)
		c_backtrace(fp, processor_mode(regs));
}

void dump_stack(void)
{
	__backtrace();
}

EXPORT_SYMBOL(dump_stack);

void show_stack(struct task_struct *tsk, unsigned long *sp)
{
	unsigned long fp;

	if (!tsk)
		tsk = current;

	if (tsk != current)
		fp = thread_saved_fp(tsk);
	else
		asm("mov %0, fp" : "=r" (fp) : : "cc");

	c_backtrace(fp, 0x10);
	barrier();
}

#ifdef CONFIG_PREEMPT
#define S_PREEMPT " PREEMPT"
#else
#define S_PREEMPT ""
#endif
#ifdef CONFIG_SMP
#define S_SMP " SMP"
#else
#define S_SMP ""
#endif

static void __die(const char *str, int err, struct thread_info *thread, struct pt_regs *regs)
{
	struct task_struct *tsk = thread->task;
	static int die_counter;

	printk("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP "\n",
	       str, err, ++die_counter);
	print_modules();
	__show_regs(regs);
	printk("Process %s (pid: %d, stack limit = 0x%p)\n",
		tsk->comm, task_pid_nr(tsk), thread + 1);

	if (!user_mode(regs) || in_interrupt()) {
		dump_mem("Stack: ", regs->ARM_sp,
			 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
		dump_backtrace(regs, tsk);
		dump_instr(regs);
	}
}

DEFINE_SPINLOCK(die_lock);

/*
 * This function is protected against re-entrancy.
 */
NORET_TYPE void die(const char *str, struct pt_regs *regs, int err)
{
	struct thread_info *thread = current_thread_info();

	oops_enter();

	console_verbose();
	spin_lock_irq(&die_lock);
	bust_spinlocks(1);
	__die(str, err, thread, regs);
	bust_spinlocks(0);
	add_taint(TAINT_DIE);
	spin_unlock_irq(&die_lock);

	if (in_interrupt())
		panic("Fatal exception in interrupt");

	if (panic_on_oops)
		panic("Fatal exception");

	oops_exit();
	do_exit(SIGSEGV);
}

void arm_notify_die(const char *str, struct pt_regs *regs,
		struct siginfo *info, unsigned long err, unsigned long trap)
{
	if (user_mode(regs)) {
		current->thread.error_code = err;
		current->thread.trap_no = trap;

		force_sig_info(info->si_signo, info, current);
	} else {
		die(str, regs, err);
	}
}

static LIST_HEAD(undef_hook);
static DEFINE_SPINLOCK(undef_lock);

void register_undef_hook(struct undef_hook *hook)
{
	unsigned long flags;

	spin_lock_irqsave(&undef_lock, flags);
	list_add(&hook->node, &undef_hook);
	spin_unlock_irqrestore(&undef_lock, flags);
}

void unregister_undef_hook(struct undef_hook *hook)
{
	unsigned long flags;

	spin_lock_irqsave(&undef_lock, flags);
	list_del(&hook->node);
	spin_unlock_irqrestore(&undef_lock, flags);
}

asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
{
	unsigned int correction = thumb_mode(regs) ? 2 : 4;
	unsigned int instr;
	struct undef_hook *hook;
	siginfo_t info;
	void __user *pc;
	unsigned long flags;

	/*
	 * According to the ARM ARM, PC is 2 or 4 bytes ahead,
	 * depending whether we're in Thumb mode or not.
	 * Correct this offset.
	 */
	regs->ARM_pc -= correction;

	pc = (void __user *)instruction_pointer(regs);

	if (processor_mode(regs) == SVC_MODE) {
		instr = *(u32 *) pc;
	} else if (thumb_mode(regs)) {
		get_user(instr, (u16 __user *)pc);
	} else {
		get_user(instr, (u32 __user *)pc);
	}

	spin_lock_irqsave(&undef_lock, flags);
	list_for_each_entry(hook, &undef_hook, node) {
		if ((instr & hook->instr_mask) == hook->instr_val &&
		    (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val) {
			if (hook->fn(regs, instr) == 0) {
				spin_unlock_irqrestore(&undef_lock, flags);
				return;
			}
		}
	}
	spin_unlock_irqrestore(&undef_lock, flags);

#ifdef CONFIG_DEBUG_USER
	if (user_debug & UDBG_UNDEFINED) {
		printk(KERN_INFO "%s (%d): undefined instruction: pc=%p\n",
			current->comm, task_pid_nr(current), pc);
		dump_instr(regs);
	}
#endif

	info.si_signo = SIGILL;
	info.si_errno = 0;
	info.si_code  = ILL_ILLOPC;
	info.si_addr  = pc;

	arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
}

asmlinkage void do_unexp_fiq (struct pt_regs *regs)
{
	printk("Hmm.  Unexpected FIQ received, but trying to continue\n");
	printk("You may have a hardware problem...\n");
}

/*
 * bad_mode handles the impossible case in the vectors.  If you see one of
 * these, then it's extremely serious, and could mean you have buggy hardware.
 * It never returns, and never tries to sync.  We hope that we can at least
 * dump out some state information...
 */
asmlinkage void bad_mode(struct pt_regs *regs, int reason)
{
	console_verbose();