dumpstack.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/utsname.h>
#include <linux/hardirq.h>
#include <linux/kdebug.h>
#include <linux/module.h>
#include <linux/ptrace.h>
#include <linux/ftrace.h>
#include <linux/kexec.h>
#include <linux/bug.h>
#include <linux/nmi.h>
#include <linux/sysfs.h>

#include <asm/stacktrace.h>


int panic_on_unrecovered_nmi;
int panic_on_io_nmi;
unsigned int code_bytes = 64;
int kstack_depth_to_print = 3 * STACKSLOTS_PER_LINE;
static int die_counter;

void printk_address(unsigned long address, int reliable)
{
    pr_cont(" [<%p>] %s%pB\n",
        (void *)address, reliable ? "" : "? ", (void *)address);
}

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static void
print_ftrace_graph_addr(unsigned long addr, void *data,
            const struct stacktrace_ops *ops,
            struct thread_info *tinfo, int *graph)
{
    struct task_struct *task;
    unsigned long ret_addr;
    int index;

    if (addr != (unsigned long)return_to_handler)
        return;

    task = tinfo->task;
    index = task->curr_ret_stack;

    if (!task->ret_stack || index < *graph)
        return;

    index -= *graph;
    ret_addr = task->ret_stack[index].ret;

    ops->address(data, ret_addr, 1);

    (*graph)++;
}
#else
static inline void
print_ftrace_graph_addr(unsigned long addr, void *data,
            const struct stacktrace_ops *ops,
            struct thread_info *tinfo, int *graph)
{ }
#endif

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

static inline int valid_stack_ptr(struct thread_info *tinfo,
            void *p, unsigned int size, void *end)
{
    void *t = tinfo;
    if (end) {
        if (p < end && p >= (end-THREAD_SIZE))
            return 1;
        else
            return 0;
    }
    return p > t && p < t + THREAD_SIZE - size;
}

unsigned long
print_context_stack(struct thread_info *tinfo,
        unsigned long *stack, unsigned long bp,
        const struct stacktrace_ops *ops, void *data,
        unsigned long *end, int *graph)
{
    struct stack_frame *frame = (struct stack_frame *)bp;

    while (valid_stack_ptr(tinfo, stack, sizeof(*stack), end)) {
        unsigned long addr;

        addr = *stack;
        if (__kernel_text_address(addr)) {
            if ((unsigned long) stack == bp + sizeof(long)) {
                ops->address(data, addr, 1);
                frame = frame->next_frame;
                bp = (unsigned long) frame;
            } else {
                ops->address(data, addr, 0);
            }
            print_ftrace_graph_addr(addr, data, ops, tinfo, graph);
        }
        stack++;
    }
    return bp;
}
EXPORT_SYMBOL_GPL(print_context_stack);

unsigned long
print_context_stack_bp(struct thread_info *tinfo,
               unsigned long *stack, unsigned long bp,
               const struct stacktrace_ops *ops, void *data,
               unsigned long *end, int *graph)
{
    struct stack_frame *frame = (struct stack_frame *)bp;
    unsigned long *ret_addr = &frame->return_address;

    while (valid_stack_ptr(tinfo, ret_addr, sizeof(*ret_addr), end)) {
        unsigned long addr = *ret_addr;

        if (!__kernel_text_address(addr))
            break;

        ops->address(data, addr, 1);
        frame = frame->next_frame;
        ret_addr = &frame->return_address;
        print_ftrace_graph_addr(addr, data, ops, tinfo, graph);
    }

    return (unsigned long)frame;
}
EXPORT_SYMBOL_GPL(print_context_stack_bp);

static int print_trace_stack(void *data, char *name)
{
    printk("%s <%s> ", (char *)data, name);
    return 0;
}

/*
 * Print one address/symbol entries per line.
 */
static void print_trace_address(void *data, unsigned long addr, int reliable)
{
    touch_nmi_watchdog();
    printk(data);
    printk_address(addr, reliable);
}

static const struct stacktrace_ops print_trace_ops = {
    .stack          = print_trace_stack,
    .address        = print_trace_address,
    .walk_stack     = print_context_stack,
};

void
show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
        unsigned long *stack, unsigned long bp, char *log_lvl)
{
    printk("%sCall Trace:\n", log_lvl);
    dump_trace(task, regs, stack, bp, &print_trace_ops, log_lvl);
}

void show_trace(struct task_struct *task, struct pt_regs *regs,
        unsigned long *stack, unsigned long bp)
{
    show_trace_log_lvl(task, regs, stack, bp, "");
}

void show_stack(struct task_struct *task, unsigned long *sp)
{
    show_stack_log_lvl(task, NULL, sp, 0, "");
}

/*
 * The architecture-independent dump_stack generator
 */
void dump_stack(void)
{
    unsigned long bp;
    unsigned long stack;

    bp = stack_frame(current, NULL);
    printk("Pid: %d, comm: %.20s %s %s %.*s\n",
        current->pid, current->comm, print_tainted(),
        init_utsname()->release,
        (int)strcspn(init_utsname()->version, " "),
        init_utsname()->version);
    show_trace(NULL, NULL, &stack, bp);
}
EXPORT_SYMBOL(dump_stack);

static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
static int die_owner = -1;
static unsigned int die_nest_count;

unsigned __kprobes long oops_begin(void)
{
    int cpu;
    unsigned long flags;

    oops_enter();

    /* racy, but better than risking deadlock. */
    raw_local_irq_save(flags);
    cpu = smp_processor_id();
    if (!arch_spin_trylock(&die_lock)) {
        if (cpu == die_owner)
            /* nested oops. should stop eventually */;
        else
            arch_spin_lock(&die_lock);
    }
    die_nest_count++;
    die_owner = cpu;
    console_verbose();
    bust_spinlocks(1);
    return flags;
}
EXPORT_SYMBOL_GPL(oops_begin);

void __kprobes oops_end(unsigned long flags, struct pt_regs *regs, int signr)
{
    if (regs && kexec_should_crash(current))
        crash_kexec(regs);

    bust_spinlocks(0);
    die_owner = -1;
    add_taint(TAINT_DIE);
    die_nest_count--;
    if (!die_nest_count)
        /* Nest count reaches zero, release the lock. */
        arch_spin_unlock(&die_lock);
    raw_local_irq_restore(flags);
    oops_exit();

    if (!signr)
        return;
    if (in_interrupt())
        panic("Fatal exception in interrupt");
    if (panic_on_oops)
        panic("Fatal exception");
    do_exit(signr);
}

int __kprobes __die(const char *str, struct pt_regs *regs, long err)
{
#ifdef CONFIG_X86_32
    unsigned short ss;
    unsigned long sp;
#endif
    printk(KERN_DEFAULT
           "%s: %04lx [#%d] ", str, err & 0xffff, ++die_counter);
#ifdef CONFIG_PREEMPT
    printk("PREEMPT ");
#endif
#ifdef CONFIG_SMP
    printk("SMP ");
#endif
#ifdef CONFIG_DEBUG_PAGEALLOC
    printk("DEBUG_PAGEALLOC");
#endif
    printk("\n");
    if (notify_die(DIE_OOPS, str, regs, err,
            current->thread.trap_nr, SIGSEGV) == NOTIFY_STOP)
        return 1;

    print_modules();
    show_regs(regs);
#ifdef CONFIG_X86_32
    if (user_mode_vm(regs)) {
        sp = regs->sp;
        ss = regs->ss & 0xffff;
    } else {
        sp = kernel_stack_pointer(regs);
        savesegment(ss, ss);
    }
    printk(KERN_EMERG "EIP: [<%08lx>] ", regs->ip);
    print_symbol("%s", regs->ip);
    printk(" SS:ESP %04x:%08lx\n", ss, sp);
#else
    /* Executive summary in case the oops scrolled away */
    printk(KERN_ALERT "RIP ");
    printk_address(regs->ip, 1);
    printk(" RSP <%016lx>\n", regs->sp);
#endif
    return 0;
}

/*
 * This is gone through when something in the kernel has done something bad
 * and is about to be terminated:
 */
void die(const char *str, struct pt_regs *regs, long err)
{
    unsigned long flags = oops_begin();
    int sig = SIGSEGV;

    if (!user_mode_vm(regs))
        report_bug(regs->ip, regs);

    if (__die(str, regs, err))
        sig = 0;
    oops_end(flags, regs, sig);
}

static int __init kstack_setup(char *s)
{
    ssize_t ret;
    unsigned long val;

    if (!s)
        return -EINVAL;

    ret = kstrtoul(s, 0, &val);
    if (ret)
        return ret;
    kstack_depth_to_print = val;
    return 0;
}
early_param("kstack", kstack_setup);

static int __init code_bytes_setup(char *s)
{
    ssize_t ret;
    unsigned long val;

    if (!s)
        return -EINVAL;

    ret = kstrtoul(s, 0, &val);
    if (ret)
        return ret;

    code_bytes = val;
    if (code_bytes > 8192)
        code_bytes = 8192;

    return 1;
}
__setup("code_bytes=", code_bytes_setup);