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

/*
 *  arch/ppc/kernel/traps.c
 *
 *  Copyright (C) 1995-1996  Gary Thomas (gdt@linuxppc.org)
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 *
 *  Modified by Cort Dougan (cort@cs.nmt.edu)
 *  and Paul Mackerras (paulus@cs.anu.edu.au)
 */

/*
 * This file handles the architecture-dependent parts of hardware exceptions
 */

#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/user.h>
#include <linux/a.out.h>
#include <linux/interrupt.h>
#include <linux/config.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/prctl.h>

#include <asm/pgtable.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/reg.h>
#include <asm/xmon.h>
#ifdef CONFIG_PMAC_BACKLIGHT
#include <asm/backlight.h>
#endif
#include <asm/pmc.h>

#ifdef CONFIG_XMON
extern int xmon_bpt(struct pt_regs *regs);
extern int xmon_sstep(struct pt_regs *regs);
extern int xmon_iabr_match(struct pt_regs *regs);
extern int xmon_dabr_match(struct pt_regs *regs);

int (*debugger)(struct pt_regs *regs) = xmon;
int (*debugger_bpt)(struct pt_regs *regs) = xmon_bpt;
int (*debugger_sstep)(struct pt_regs *regs) = xmon_sstep;
int (*debugger_iabr_match)(struct pt_regs *regs) = xmon_iabr_match;
int (*debugger_dabr_match)(struct pt_regs *regs) = xmon_dabr_match;
void (*debugger_fault_handler)(struct pt_regs *regs);
#else
#ifdef CONFIG_KGDB
int (*debugger)(struct pt_regs *regs);
int (*debugger_bpt)(struct pt_regs *regs);
int (*debugger_sstep)(struct pt_regs *regs);
int (*debugger_iabr_match)(struct pt_regs *regs);
int (*debugger_dabr_match)(struct pt_regs *regs);
void (*debugger_fault_handler)(struct pt_regs *regs);
#else
#define debugger(regs)			do { } while (0)
#define debugger_bpt(regs)		0
#define debugger_sstep(regs)		0
#define debugger_iabr_match(regs)	0
#define debugger_dabr_match(regs)	0
#define debugger_fault_handler		((void (*)(struct pt_regs *))0)
#endif
#endif

/*
 * Trap & Exception support
 */

DEFINE_SPINLOCK(die_lock);

int die(const char * str, struct pt_regs * fp, long err)
{
	static int die_counter;
	int nl = 0;
	console_verbose();
	spin_lock_irq(&die_lock);
#ifdef CONFIG_PMAC_BACKLIGHT
	if (_machine == _MACH_Pmac) {
		set_backlight_enable(1);
		set_backlight_level(BACKLIGHT_MAX);
	}
#endif
	printk("Oops: %s, sig: %ld [#%d]\n", str, err, ++die_counter);
#ifdef CONFIG_PREEMPT
	printk("PREEMPT ");
	nl = 1;
#endif
#ifdef CONFIG_SMP
	printk("SMP NR_CPUS=%d ", NR_CPUS);
	nl = 1;
#endif
	if (nl)
		printk("\n");
	show_regs(fp);
	spin_unlock_irq(&die_lock);
	/* do_exit() should take care of panic'ing from an interrupt
	 * context so we don't handle it here
	 */
	do_exit(err);
}

void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr)
{
	siginfo_t info;

	if (!user_mode(regs)) {
		debugger(regs);
		die("Exception in kernel mode", regs, signr);
	}
	info.si_signo = signr;
	info.si_errno = 0;
	info.si_code = code;
	info.si_addr = (void __user *) addr;
	force_sig_info(signr, &info, current);

	/*
	 * Init gets no signals that it doesn't have a handler for.
	 * That's all very well, but if it has caused a synchronous
	 * exception and we ignore the resulting signal, it will just
	 * generate the same exception over and over again and we get
	 * nowhere.  Better to kill it and let the kernel panic.
	 */
	if (current->pid == 1) {
		__sighandler_t handler;

		spin_lock_irq(&current->sighand->siglock);
		handler = current->sighand->action[signr-1].sa.sa_handler;
		spin_unlock_irq(&current->sighand->siglock);
		if (handler == SIG_DFL) {
			/* init has generated a synchronous exception
			   and it doesn't have a handler for the signal */
			printk(KERN_CRIT "init has generated signal %d "
			       "but has no handler for it\n", signr);
			do_exit(signr);
		}
	}
}

/*
 * I/O accesses can cause machine checks on powermacs.
 * Check if the NIP corresponds to the address of a sync
 * instruction for which there is an entry in the exception
 * table.
 * Note that the 601 only takes a machine check on TEA
 * (transfer error ack) signal assertion, and does not
 * set any of the top 16 bits of SRR1.
 *  -- paulus.
 */
static inline int check_io_access(struct pt_regs *regs)
{
#if defined CONFIG_PPC_PMAC || defined CONFIG_8xx
	unsigned long msr = regs->msr;
	const struct exception_table_entry *entry;
	unsigned int *nip = (unsigned int *)regs->nip;

	if (((msr & 0xffff0000) == 0 || (msr & (0x80000 |