dumpstack_64.c

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/*
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *  Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs
 */
#include <linux/kallsyms.h>
#include <linux/kprobes.h>
#include <linux/uaccess.h>
#include <linux/hardirq.h>
#include <linux/kdebug.h>
#include <linux/module.h>
#include <linux/ptrace.h>
#include <linux/kexec.h>
#include <linux/sysfs.h>
#include <linux/bug.h>
#include <linux/nmi.h>

#include <asm/stacktrace.h>


#define N_EXCEPTION_STACKS_END \
        (N_EXCEPTION_STACKS + DEBUG_STKSZ/EXCEPTION_STKSZ - 2)

static char x86_stack_ids[][8] = {
        [ DEBUG_STACK-1         ]   = "#DB",
        [ NMI_STACK-1           ]   = "NMI",
        [ DOUBLEFAULT_STACK-1       ]   = "#DF",
        [ STACKFAULT_STACK-1        ]   = "#SS",
        [ MCE_STACK-1           ]   = "#MC",
#if DEBUG_STKSZ > EXCEPTION_STKSZ
        [ N_EXCEPTION_STACKS ...
          N_EXCEPTION_STACKS_END    ]   = "#DB[?]"
#endif
};

static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
                     unsigned *usedp, char **idp)
{
    unsigned k;

    /*
     * Iterate over all exception stacks, and figure out whether
     * 'stack' is in one of them:
     */
    for (k = 0; k < N_EXCEPTION_STACKS; k++) {
        unsigned long end = per_cpu(orig_ist, cpu).ist[k];
        /*
         * Is 'stack' above this exception frame's end?
         * If yes then skip to the next frame.
         */
        if (stack >= end)
            continue;
        /*
         * Is 'stack' above this exception frame's start address?
         * If yes then we found the right frame.
         */
        if (stack >= end - EXCEPTION_STKSZ) {
            /*
             * Make sure we only iterate through an exception
             * stack once. If it comes up for the second time
             * then there's something wrong going on - just
             * break out and return NULL:
             */
            if (*usedp & (1U << k))
                break;
            *usedp |= 1U << k;
            *idp = x86_stack_ids[k];
            return (unsigned long *)end;
        }
        /*
         * If this is a debug stack, and if it has a larger size than
         * the usual exception stacks, then 'stack' might still
         * be within the lower portion of the debug stack:
         */
#if DEBUG_STKSZ > EXCEPTION_STKSZ
        if (k == DEBUG_STACK - 1 && stack >= end - DEBUG_STKSZ) {
            unsigned j = N_EXCEPTION_STACKS - 1;

            /*
             * Black magic. A large debug stack is composed of
             * multiple exception stack entries, which we
             * iterate through now. Dont look:
             */
            do {
                ++j;
                end -= EXCEPTION_STKSZ;
                x86_stack_ids[j][4] = '1' +
                        (j - N_EXCEPTION_STACKS);
            } while (stack < end - EXCEPTION_STKSZ);
            if (*usedp & (1U << j))
                break;
            *usedp |= 1U << j;
            *idp = x86_stack_ids[j];
            return (unsigned long *)end;
        }
#endif
    }
    return NULL;
}

static inline int
in_irq_stack(unsigned long *stack, unsigned long *irq_stack,
         unsigned long *irq_stack_end)
{
    return (stack >= irq_stack && stack < irq_stack_end);
}

/*
 * x86-64 can have up to three kernel stacks:
 * process stack
 * interrupt stack
 * severe exception (double fault, nmi, stack fault, debug, mce) hardware stack
 */

void dump_trace(struct task_struct *task, struct pt_regs *regs,
        unsigned long *stack, unsigned long bp,
        const struct stacktrace_ops *ops, void *data)
{
    const unsigned cpu = get_cpu();
    unsigned long *irq_stack_end =
        (unsigned long *)per_cpu(irq_stack_ptr, cpu);
    unsigned used = 0;
    struct thread_info *tinfo;
    int graph = 0;
    unsigned long dummy;

    if (!task)
        task = current;

    if (!stack) {
        if (regs)
            stack = (unsigned long *)regs->sp;
        else if (task != current)
            stack = (unsigned long *)task->thread.sp;
        else
            stack = &dummy;
    }

    if (!bp)
        bp = stack_frame(task, regs);
    /*
     * Print function call entries in all stacks, starting at the
     * current stack address. If the stacks consist of nested
     * exceptions
     */
    tinfo = task_thread_info(task);
    for (;;) {
        char *id;
        unsigned long *estack_end;
        estack_end = in_exception_stack(cpu, (unsigned long)stack,
                        &used, &id);

        if (estack_end) {
            if (ops->stack(data, id) < 0)
                break;

            bp = ops->walk_stack(tinfo, stack, bp, ops,
                         data, estack_end, &graph);
            ops->stack(data, "<EOE>");
            /*
             * We link to the next stack via the
             * second-to-last pointer (index -2 to end) in the
             * exception stack:
             */
            stack = (unsigned long *) estack_end[-2];
            continue;
        }
        if (irq_stack_end) {
            unsigned long *irq_stack;
            irq_stack = irq_stack_end -
                (IRQ_STACK_SIZE - 64) / sizeof(*irq_stack);

            if (in_irq_stack(stack, irq_stack, irq_stack_end)) {
                if (ops->stack(data, "IRQ") < 0)
                    break;
                bp = ops->walk_stack(tinfo, stack, bp,
                    ops, data, irq_stack_end, &graph);
                /*
                 * We link to the next stack (which would be
                 * the process stack normally) the last
                 * pointer (index -1 to end) in the IRQ stack:
                 */
                stack = (unsigned long *) (irq_stack_end[-1]);
                irq_stack_end = NULL;
                ops->stack(data, "EOI");
                continue;
            }
        }
        break;
    }

    /*
     * This handles the process stack:
     */
    bp = ops->walk_stack(tinfo, stack, bp, ops, data, NULL, &graph);
    put_cpu();
}
EXPORT_SYMBOL(dump_trace);

void
show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
           unsigned long *sp, unsigned long bp, char *log_lvl)
{
    unsigned long *irq_stack_end;
    unsigned long *irq_stack;
    unsigned long *stack;
    int cpu;
    int i;

    preempt_disable();
    cpu = smp_processor_id();

    irq_stack_end   = (unsigned long *)(per_cpu(irq_stack_ptr, cpu));
    irq_stack   = (unsigned long *)(per_cpu(irq_stack_ptr, cpu) - IRQ_STACK_SIZE);

    /*
     * Debugging aid: "show_stack(NULL, NULL);" prints the
     * back trace for this cpu:
     */
    if (sp == NULL) {
        if (task)
            sp = (unsigned long *)task->thread.sp;
        else
            sp = (unsigned long *)&sp;
    }

    stack = sp;
    for (i = 0; i < kstack_depth_to_print; i++) {
        if (stack >= irq_stack && stack <= irq_stack_end) {
            if (stack == irq_stack_end) {
                stack = (unsigned long *) (irq_stack_end[-1]);
                pr_cont(" <EOI> ");
            }
        } else {
        if (((long) stack & (THREAD_SIZE-1)) == 0)
            break;
        }
        if (i && ((i % STACKSLOTS_PER_LINE) == 0))
            pr_cont("\n");
        pr_cont(" %016lx", *stack++);
        touch_nmi_watchdog();
    }
    preempt_enable();

    pr_cont("\n");
    show_trace_log_lvl(task, regs, sp, bp, log_lvl);
}

void show_regs(struct pt_regs *regs)
{
    int i;
    unsigned long sp;
    const int cpu = smp_processor_id();
    struct task_struct *cur = current;

    sp = regs->sp;
    printk("CPU %d ", cpu);
    __show_regs(regs, 1);
    printk(KERN_DEFAULT "Process %s (pid: %d, threadinfo %p, task %p)\n",
           cur->comm, cur->pid, task_thread_info(cur), cur);

    /*
     * When in-kernel, we also print out the stack and code at the
     * time of the fault..
     */
    if (!user_mode(regs)) {
        unsigned int code_prologue = code_bytes * 43 / 64;
        unsigned int code_len = code_bytes;
        unsigned char c;
        u8 *ip;

        printk(KERN_DEFAULT "Stack:\n");
        show_stack_log_lvl(NULL, regs, (unsigned long *)sp,
                   0, KERN_DEFAULT);

        printk(KERN_DEFAULT "Code: ");

        ip = (u8 *)regs->ip - code_prologue;
        if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
            /* try starting at IP */
            ip = (u8 *)regs->ip;
            code_len = code_len - code_prologue + 1;
        }
        for (i = 0; i < code_len; i++, ip++) {
            if (ip < (u8 *)PAGE_OFFSET ||
                    probe_kernel_address(ip, c)) {
                pr_cont(" Bad RIP value.");
                break;
            }
            if (ip == (u8 *)regs->ip)
                pr_cont("<%02x> ", c);
            else
                pr_cont("%02x ", c);
        }
    }
    pr_cont("\n");
}

int is_valid_bugaddr(unsigned long ip)
{
    unsigned short ud2;

    if (__copy_from_user(&ud2, (const void __user *) ip, sizeof(ud2)))
        return 0;

    return ud2 == 0x0b0f;
}