stacktrace.c

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/*
 * Stack trace management functions
 *
 *  Copyright (C) 2009 Helge Deller <[email protected]>
 *  based on arch/x86/kernel/stacktrace.c by Ingo Molnar <[email protected]>
 *  and parisc unwind functions by Randolph Chung <[email protected]>
 *
 *  TODO: Userspace stacktrace (CONFIG_USER_STACKTRACE_SUPPORT)
 */
#include <linux/module.h>
#include <linux/stacktrace.h>

#include <asm/unwind.h>

static void dump_trace(struct task_struct *task, struct stack_trace *trace)
{
    struct unwind_frame_info info;

    /* initialize unwind info */
    if (task == current) {
        unsigned long sp;
        struct pt_regs r;
HERE:
        asm volatile ("copy %%r30, %0" : "=r"(sp));
        memset(&r, 0, sizeof(struct pt_regs));
        r.iaoq[0] = (unsigned long)&&HERE;
        r.gr[2] = (unsigned long)__builtin_return_address(0);
        r.gr[30] = sp;
        unwind_frame_init(&info, task, &r);
    } else {
        unwind_frame_init_from_blocked_task(&info, task);
    }

    /* unwind stack and save entries in stack_trace struct */
    trace->nr_entries = 0;
    while (trace->nr_entries < trace->max_entries) {
        if (unwind_once(&info) < 0 || info.ip == 0)
            break;

        if (__kernel_text_address(info.ip))
            trace->entries[trace->nr_entries++] = info.ip;
    }
}


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