traps.c

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/*
 * Copyright (C) 2004-2006 Atmel Corporation
 *
 * 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.
 */

#include <linux/bug.h>
#include <linux/hardirq.h>
#include <linux/init.h>
#include <linux/kallsyms.h>
#include <linux/kdebug.h>
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/sched.h>
#include <linux/uaccess.h>

#include <asm/addrspace.h>
#include <asm/mmu_context.h>
#include <asm/ocd.h>
#include <asm/sysreg.h>
#include <asm/traps.h>

static DEFINE_SPINLOCK(die_lock);

void die(const char *str, struct pt_regs *regs, long err)
{
    static int die_counter;

    console_verbose();
    spin_lock_irq(&die_lock);
    bust_spinlocks(1);

    printk(KERN_ALERT "Oops: %s, sig: %ld [#%d]\n",
           str, err, ++die_counter);

    printk(KERN_EMERG);

#ifdef CONFIG_PREEMPT
    printk(KERN_CONT "PREEMPT ");
#endif
#ifdef CONFIG_FRAME_POINTER
    printk(KERN_CONT "FRAME_POINTER ");
#endif
    if (current_cpu_data.features & AVR32_FEATURE_OCD) {
        unsigned long did = ocd_read(DID);
        printk(KERN_CONT "chip: 0x%03lx:0x%04lx rev %lu\n",
               (did >> 1) & 0x7ff,
               (did >> 12) & 0x7fff,
               (did >> 28) & 0xf);
    } else {
        printk(KERN_CONT "cpu: arch %u r%u / core %u r%u\n",
               current_cpu_data.arch_type,
               current_cpu_data.arch_revision,
               current_cpu_data.cpu_type,
               current_cpu_data.cpu_revision);
    }

    print_modules();
    show_regs_log_lvl(regs, KERN_EMERG);
    show_stack_log_lvl(current, regs->sp, regs, KERN_EMERG);
    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");

    do_exit(err);
}

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

    if (!user_mode(regs)) {
        const struct exception_table_entry *fixup;

        /* Are we prepared to handle this kernel fault? */
        fixup = search_exception_tables(regs->pc);
        if (fixup) {
            regs->pc = fixup->fixup;
            return;
        }
        die("Unhandled exception in kernel mode", regs, signr);
    }

    memset(&info, 0, sizeof(info));
    info.si_signo = signr;
    info.si_code = code;
    info.si_addr = (void __user *)addr;
    force_sig_info(signr, &info, current);
}

asmlinkage void do_nmi(unsigned long ecr, struct pt_regs *regs)
{
    int ret;

    nmi_enter();

    ret = notify_die(DIE_NMI, "NMI", regs, 0, ecr, SIGINT);
    switch (ret) {
    case NOTIFY_OK:
    case NOTIFY_STOP:
        break;
    case NOTIFY_BAD:
        die("Fatal Non-Maskable Interrupt", regs, SIGINT);
    default:
        printk(KERN_ALERT "Got NMI, but nobody cared. Disabling...\n");
        nmi_disable();
        break;
    }
    nmi_exit();
}

asmlinkage void do_critical_exception(unsigned long ecr, struct pt_regs *regs)
{
    die("Critical exception", regs, SIGKILL);
}

asmlinkage void do_address_exception(unsigned long ecr, struct pt_regs *regs)
{
    _exception(SIGBUS, regs, BUS_ADRALN, regs->pc);
}

/* This way of handling undefined instructions is stolen from ARM */
static LIST_HEAD(undef_hook);
static DEFINE_SPINLOCK(undef_lock);

void register_undef_hook(struct undef_hook *hook)
{
    spin_lock_irq(&undef_lock);
    list_add(&hook->node, &undef_hook);
    spin_unlock_irq(&undef_lock);
}

void unregister_undef_hook(struct undef_hook *hook)
{
    spin_lock_irq(&undef_lock);
    list_del(&hook->node);
    spin_unlock_irq(&undef_lock);
}

static int do_cop_absent(u32 insn)
{
    int cop_nr;
    u32 cpucr;

    if ((insn & 0xfdf00000) == 0xf1900000)
        /* LDC0 */
        cop_nr = 0;
    else
        cop_nr = (insn >> 13) & 0x7;

    /* Try enabling the coprocessor */
    cpucr = sysreg_read(CPUCR);
    cpucr |= (1 << (24 + cop_nr));
    sysreg_write(CPUCR, cpucr);

    cpucr = sysreg_read(CPUCR);
    if (!(cpucr & (1 << (24 + cop_nr))))
        return -ENODEV;

    return 0;
}

#ifdef CONFIG_BUG
int is_valid_bugaddr(unsigned long pc)
{
    unsigned short opcode;

    if (pc < PAGE_OFFSET)
        return 0;
    if (probe_kernel_address((u16 *)pc, opcode))
        return 0;

    return opcode == AVR32_BUG_OPCODE;
}
#endif

asmlinkage void do_illegal_opcode(unsigned long ecr, struct pt_regs *regs)
{
    u32 insn;
    struct undef_hook *hook;
    void __user *pc;
    long code;

#ifdef CONFIG_BUG
    if (!user_mode(regs) && (ecr == ECR_ILLEGAL_OPCODE)) {
        enum bug_trap_type type;

        type = report_bug(regs->pc, regs);
        switch (type) {
        case BUG_TRAP_TYPE_NONE:
            break;
        case BUG_TRAP_TYPE_WARN:
            regs->pc += 2;
            return;
        case BUG_TRAP_TYPE_BUG:
            die("Kernel BUG", regs, SIGKILL);
        }
    }
#endif

    local_irq_enable();

    if (user_mode(regs)) {
        pc = (void __user *)instruction_pointer(regs);
        if (get_user(insn, (u32 __user *)pc))
            goto invalid_area;

        if (ecr == ECR_COPROC_ABSENT && !do_cop_absent(insn))
            return;

        spin_lock_irq(&undef_lock);
        list_for_each_entry(hook, &undef_hook, node) {
            if ((insn & hook->insn_mask) == hook->insn_val) {
                if (hook->fn(regs, insn) == 0) {
                    spin_unlock_irq(&undef_lock);
                    return;
                }
            }
        }
        spin_unlock_irq(&undef_lock);
    }

    switch (ecr) {
    case ECR_PRIVILEGE_VIOLATION:
        code = ILL_PRVOPC;
        break;
    case ECR_COPROC_ABSENT:
        code = ILL_COPROC;
        break;
    default:
        code = ILL_ILLOPC;
        break;
    }

    _exception(SIGILL, regs, code, regs->pc);
    return;

invalid_area:
    _exception(SIGSEGV, regs, SEGV_MAPERR, regs->pc);
}

asmlinkage void do_fpe(unsigned long ecr, struct pt_regs *regs)
{
    /* We have no FPU yet */
    _exception(SIGILL, regs, ILL_COPROC, regs->pc);
}


void __init trap_init(void)
{

}