stacktrace.c

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/*
 * Stack trace management functions
 *
 *  Copyright (C) 2006-2009 Red Hat, Inc., Ingo Molnar <[email protected]>
 */
#include <linux/sched.h>
#include <linux/stacktrace.h>
#include <linux/module.h>
#include <linux/uaccess.h>
#include <asm/stacktrace.h>

static int save_stack_stack(void *data, char *name)
{
    return 0;
}

static void
__save_stack_address(void *data, unsigned long addr, bool reliable, bool nosched)
{
    struct stack_trace *trace = data;
#ifdef CONFIG_FRAME_POINTER
    if (!reliable)
        return;
#endif
    if (nosched && in_sched_functions(addr))
        return;
    if (trace->skip > 0) {
        trace->skip--;
        return;
    }
    if (trace->nr_entries < trace->max_entries)
        trace->entries[trace->nr_entries++] = addr;
}

static void save_stack_address(void *data, unsigned long addr, int reliable)
{
    return __save_stack_address(data, addr, reliable, false);
}

static void
save_stack_address_nosched(void *data, unsigned long addr, int reliable)
{
    return __save_stack_address(data, addr, reliable, true);
}

static const struct stacktrace_ops save_stack_ops = {
    .stack      = save_stack_stack,
    .address    = save_stack_address,
    .walk_stack = print_context_stack,
};

static const struct stacktrace_ops save_stack_ops_nosched = {
    .stack      = save_stack_stack,
    .address    = save_stack_address_nosched,
    .walk_stack = print_context_stack,
};

/*
 * Save stack-backtrace addresses into a stack_trace buffer.
 */
void save_stack_trace(struct stack_trace *trace)
{
    dump_trace(current, NULL, NULL, 0, &save_stack_ops, trace);
    if (trace->nr_entries < trace->max_entries)
        trace->entries[trace->nr_entries++] = ULONG_MAX;
}
EXPORT_SYMBOL_GPL(save_stack_trace);

void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
{
    dump_trace(current, regs, NULL, 0, &save_stack_ops, trace);
    if (trace->nr_entries < trace->max_entries)
        trace->entries[trace->nr_entries++] = ULONG_MAX;
}

void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
{
    dump_trace(tsk, NULL, NULL, 0, &save_stack_ops_nosched, trace);
    if (trace->nr_entries < trace->max_entries)
        trace->entries[trace->nr_entries++] = ULONG_MAX;
}
EXPORT_SYMBOL_GPL(save_stack_trace_tsk);

/* Userspace stacktrace - based on kernel/trace/trace_sysprof.c */

struct stack_frame_user {
    const void __user   *next_fp;
    unsigned long       ret_addr;
};

static int
copy_stack_frame(const void __user *fp, struct stack_frame_user *frame)
{
    int ret;

    if (!access_ok(VERIFY_READ, fp, sizeof(*frame)))
        return 0;

    ret = 1;
    pagefault_disable();
    if (__copy_from_user_inatomic(frame, fp, sizeof(*frame)))
        ret = 0;
    pagefault_enable();

    return ret;
}

static inline void __save_stack_trace_user(struct stack_trace *trace)
{
    const struct pt_regs *regs = task_pt_regs(current);
    const void __user *fp = (const void __user *)regs->bp;

    if (trace->nr_entries < trace->max_entries)
        trace->entries[trace->nr_entries++] = regs->ip;

    while (trace->nr_entries < trace->max_entries) {
        struct stack_frame_user frame;

        frame.next_fp = NULL;
        frame.ret_addr = 0;
        if (!copy_stack_frame(fp, &frame))
            break;
        if ((unsigned long)fp < regs->sp)
            break;
        if (frame.ret_addr) {
            trace->entries[trace->nr_entries++] =
                frame.ret_addr;
        }
        if (fp == frame.next_fp)
            break;
        fp = frame.next_fp;
    }
}

void save_stack_trace_user(struct stack_trace *trace)
{
    /*
     * Trace user stack if we are not a kernel thread
     */
    if (current->mm) {
        __save_stack_trace_user(trace);
    }
    if (trace->nr_entries < trace->max_entries)
        trace->entries[trace->nr_entries++] = ULONG_MAX;
}