stacktrace.c

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/*
 * Stack trace management functions
 *
 *  Copyright (C) 2006 Atsushi Nemoto <[email protected]>
 */
#include <linux/sched.h>
#include <linux/stacktrace.h>
#include <linux/export.h>
#include <asm/stacktrace.h>

/*
 * Save stack-backtrace addresses into a stack_trace buffer:
 */
static void save_raw_context_stack(struct stack_trace *trace,
    unsigned long reg29)
{
    unsigned long *sp = (unsigned long *)reg29;
    unsigned long addr;

    while (!kstack_end(sp)) {
        addr = *sp++;
        if (__kernel_text_address(addr)) {
            if (trace->skip > 0)
                trace->skip--;
            else
                trace->entries[trace->nr_entries++] = addr;
            if (trace->nr_entries >= trace->max_entries)
                break;
        }
    }
}

static void save_context_stack(struct stack_trace *trace,
    struct task_struct *tsk, struct pt_regs *regs)
{
    unsigned long sp = regs->regs[29];
#ifdef CONFIG_KALLSYMS
    unsigned long ra = regs->regs[31];
    unsigned long pc = regs->cp0_epc;

    if (raw_show_trace || !__kernel_text_address(pc)) {
        unsigned long stack_page =
            (unsigned long)task_stack_page(tsk);
        if (stack_page && sp >= stack_page &&
            sp <= stack_page + THREAD_SIZE - 32)
            save_raw_context_stack(trace, sp);
        return;
    }
    do {
        if (trace->skip > 0)
            trace->skip--;
        else
            trace->entries[trace->nr_entries++] = pc;
        if (trace->nr_entries >= trace->max_entries)
            break;
        pc = unwind_stack(tsk, &sp, pc, &ra);
    } while (pc);
#else
    save_raw_context_stack(trace, sp);
#endif
}

/*
 * Save stack-backtrace addresses into a stack_trace buffer.
 */
void save_stack_trace(struct stack_trace *trace)
{
    save_stack_trace_tsk(current, trace);
}
EXPORT_SYMBOL_GPL(save_stack_trace);

void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
{
    struct pt_regs dummyregs;
    struct pt_regs *regs = &dummyregs;

    WARN_ON(trace->nr_entries || !trace->max_entries);

    if (tsk != current) {
        regs->regs[29] = tsk->thread.reg29;
        regs->regs[31] = 0;
        regs->cp0_epc = tsk->thread.reg31;
    } else
        prepare_frametrace(regs);
    save_context_stack(trace, tsk, regs);
}
EXPORT_SYMBOL_GPL(save_stack_trace_tsk);