traps.c

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/*
 * Based on arch/arm/kernel/traps.c
 *
 * Copyright (C) 1995-2009 Russell King
 * Copyright (C) 2012 ARM Ltd.
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#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/delay.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/syscalls.h>

#include <asm/atomic.h>
#include <asm/traps.h>
#include <asm/stacktrace.h>
#include <asm/exception.h>
#include <asm/system_misc.h>

static const char *handler[]= {
    "Synchronous Abort",
    "IRQ",
    "FIQ",
    "Error"
};

int show_unhandled_signals = 1;

/*
 * 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%016lx to 0x%016lx)\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 int val;
                if (__get_user(val, (unsigned int *)p) == 0)
                    sprintf(str + i * 9, " %08x", val);
                else
                    sprintf(str + i * 9, " ????????");
            }
        }
        printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
    }

    set_fs(fs);
}

static void dump_backtrace_entry(unsigned long where, unsigned long stack)
{
    print_ip_sym(where);
    if (in_exception_text(where))
        dump_mem("", "Exception stack", stack,
             stack + sizeof(struct pt_regs));
}

static void dump_instr(const char *lvl, struct pt_regs *regs)
{
    unsigned long addr = instruction_pointer(regs);
    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; i++) {
        unsigned int val, bad;

        bad = __get_user(val, &((u32 *)addr)[i]);

        if (!bad)
            p += sprintf(p, i == 0 ? "(%08x) " : "%08x ", val);
        else {
            p += sprintf(p, "bad PC value");
            break;
        }
    }
    printk("%sCode: %s\n", lvl, str);

    set_fs(fs);
}

static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
{
    struct stackframe frame;
    const register unsigned long current_sp asm ("sp");

    pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);

    if (!tsk)
        tsk = current;

    if (regs) {
        frame.fp = regs->regs[29];
        frame.sp = regs->sp;
        frame.pc = regs->pc;
    } else if (tsk == current) {
        frame.fp = (unsigned long)__builtin_frame_address(0);
        frame.sp = current_sp;
        frame.pc = (unsigned long)dump_backtrace;
    } else {
        /*
         * task blocked in __switch_to
         */
        frame.fp = thread_saved_fp(tsk);
        frame.sp = thread_saved_sp(tsk);
        frame.pc = thread_saved_pc(tsk);
    }

    printk("Call trace:\n");
    while (1) {
        unsigned long where = frame.pc;
        int ret;

        ret = unwind_frame(&frame);
        if (ret < 0)
            break;
        dump_backtrace_entry(where, frame.sp);
    }
}

void dump_stack(void)
{
    dump_backtrace(NULL, NULL);
}

EXPORT_SYMBOL(dump_stack);

void show_stack(struct task_struct *tsk, unsigned long *sp)
{
    dump_backtrace(NULL, tsk);
    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 int __die(const char *str, int err, struct thread_info *thread,
         struct pt_regs *regs)
{
    struct task_struct *tsk = thread->task;
    static int die_counter;
    int ret;

    pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP "\n",
         str, err, ++die_counter);

    /* trap and error numbers are mostly meaningless on ARM */
    ret = notify_die(DIE_OOPS, str, regs, err, 0, SIGSEGV);
    if (ret == NOTIFY_STOP)
        return ret;

    print_modules();
    __show_regs(regs);
    pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
         TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), thread + 1);

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

    return ret;
}

static DEFINE_RAW_SPINLOCK(die_lock);

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

    oops_enter();

    raw_spin_lock_irq(&die_lock);
    console_verbose();
    bust_spinlocks(1);
    ret = __die(str, err, thread, regs);

    if (regs && kexec_should_crash(thread->task))
        crash_kexec(regs);

    bust_spinlocks(0);
    add_taint(TAINT_DIE);
    raw_spin_unlock_irq(&die_lock);
    oops_exit();

    if (in_interrupt())
        panic("Fatal exception in interrupt");
    if (panic_on_oops)
        panic("Fatal exception");
    if (ret != NOTIFY_STOP)
        do_exit(SIGSEGV);
}

void arm64_notify_die(const char *str, struct pt_regs *regs,
              struct siginfo *info, int err)
{
    if (user_mode(regs))
        force_sig_info(info->si_signo, info, current);
    else
        die(str, regs, err);
}

asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
{
    siginfo_t info;
    void __user *pc = (void __user *)instruction_pointer(regs);

#ifdef CONFIG_COMPAT
    /* check for AArch32 breakpoint instructions */
    if (compat_user_mode(regs) && aarch32_break_trap(regs) == 0)
        return;
#endif

    if (show_unhandled_signals) {
        pr_info("%s[%d]: undefined instruction: pc=%p\n",
            current->comm, task_pid_nr(current), pc);
        dump_instr(KERN_INFO, regs);
    }

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

    arm64_notify_die("Oops - undefined instruction", regs, &info, 0);
}

long compat_arm_syscall(struct pt_regs *regs);

asmlinkage long do_ni_syscall(struct pt_regs *regs)
{
#ifdef CONFIG_COMPAT
    long ret;
    if (is_compat_task()) {
        ret = compat_arm_syscall(regs);
        if (ret != -ENOSYS)
            return ret;
    }
#endif

    if (show_unhandled_signals) {
        pr_info("%s[%d]: syscall %d\n", current->comm,
            task_pid_nr(current), (int)regs->syscallno);
        dump_instr("", regs);
        if (user_mode(regs))
            __show_regs(regs);
    }

    return sys_ni_syscall();
}

/*
 * bad_mode handles the impossible case in the exception vector.
 */
asmlinkage void bad_mode(struct pt_regs *regs, int reason, unsigned int esr)
{
    console_verbose();

    pr_crit("Bad mode in %s handler detected, code 0x%08x\n",
        handler[reason], esr);

    die("Oops - bad mode", regs, 0);
    local_irq_disable();
    panic("bad mode");
}

void __pte_error(const char *file, int line, unsigned long val)
{
    printk("%s:%d: bad pte %016lx.\n", file, line, val);
}

void __pmd_error(const char *file, int line, unsigned long val)
{
    printk("%s:%d: bad pmd %016lx.\n", file, line, val);
}

void __pgd_error(const char *file, int line, unsigned long val)
{
    printk("%s:%d: bad pgd %016lx.\n", file, line, val);
}

void __init trap_init(void)
{
    return;
}