dumpstack.c

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/* Provide basic stack dumping functions
 *
 * Copyright 2004-2009 Analog Devices Inc.
 *
 * Licensed under the GPL-2 or later
 */

#include <linux/kernel.h>
#include <linux/thread_info.h>
#include <linux/mm.h>
#include <linux/uaccess.h>
#include <linux/module.h>
#include <asm/trace.h>

/*
 * Checks to see if the address pointed to is either a
 * 16-bit CALL instruction, or a 32-bit CALL instruction
 */
static bool is_bfin_call(unsigned short *addr)
{
    unsigned int opcode;

    if (!get_instruction(&opcode, addr))
        return false;

    if ((opcode >= 0x0060 && opcode <= 0x0067) ||
        (opcode >= 0x0070 && opcode <= 0x0077) ||
        (opcode >= 0xE3000000 && opcode <= 0xE3FFFFFF))
        return true;

    return false;

}

void show_stack(struct task_struct *task, unsigned long *stack)
{
#ifdef CONFIG_PRINTK
    unsigned int *addr, *endstack, *fp = 0, *frame;
    unsigned short *ins_addr;
    char buf[150];
    unsigned int i, j, ret_addr, frame_no = 0;

    /*
     * If we have been passed a specific stack, use that one otherwise
     *    if we have been passed a task structure, use that, otherwise
     *    use the stack of where the variable "stack" exists
     */

    if (stack == NULL) {
        if (task) {
            /* We know this is a kernel stack, so this is the start/end */
            stack = (unsigned long *)task->thread.ksp;
            endstack = (unsigned int *)(((unsigned int)(stack) & ~(THREAD_SIZE - 1)) + THREAD_SIZE);
        } else {
            /* print out the existing stack info */
            stack = (unsigned long *)&stack;
            endstack = (unsigned int *)PAGE_ALIGN((unsigned int)stack);
        }
    } else
        endstack = (unsigned int *)PAGE_ALIGN((unsigned int)stack);

    printk(KERN_NOTICE "Stack info:\n");
    decode_address(buf, (unsigned int)stack);
    printk(KERN_NOTICE " SP: [0x%p] %s\n", stack, buf);

    if (!access_ok(VERIFY_READ, stack, (unsigned int)endstack - (unsigned int)stack)) {
        printk(KERN_NOTICE "Invalid stack pointer\n");
        return;
    }

    /* First thing is to look for a frame pointer */
    for (addr = (unsigned int *)((unsigned int)stack & ~0xF); addr < endstack; addr++) {
        if (*addr & 0x1)
            continue;
        ins_addr = (unsigned short *)*addr;
        ins_addr--;
        if (is_bfin_call(ins_addr))
            fp = addr - 1;

        if (fp) {
            /* Let's check to see if it is a frame pointer */
            while (fp >= (addr - 1) && fp < endstack
                   && fp && ((unsigned int) fp & 0x3) == 0)
                fp = (unsigned int *)*fp;
            if (fp == 0 || fp == endstack) {
                fp = addr - 1;
                break;
            }
            fp = 0;
        }
    }
    if (fp) {
        frame = fp;
        printk(KERN_NOTICE " FP: (0x%p)\n", fp);
    } else
        frame = 0;

    /*
     * Now that we think we know where things are, we
     * walk the stack again, this time printing things out
     * incase there is no frame pointer, we still look for
     * valid return addresses
     */

    /* First time print out data, next time, print out symbols */
    for (j = 0; j <= 1; j++) {
        if (j)
            printk(KERN_NOTICE "Return addresses in stack:\n");
        else
            printk(KERN_NOTICE " Memory from 0x%08lx to %p", ((long unsigned int)stack & ~0xF), endstack);

        fp = frame;
        frame_no = 0;

        for (addr = (unsigned int *)((unsigned int)stack & ~0xF), i = 0;
             addr < endstack; addr++, i++) {

            ret_addr = 0;
            if (!j && i % 8 == 0)
                printk(KERN_NOTICE "%p:", addr);

            /* if it is an odd address, or zero, just skip it */
            if (*addr & 0x1 || !*addr)
                goto print;

            ins_addr = (unsigned short *)*addr;

            /* Go back one instruction, and see if it is a CALL */
            ins_addr--;
            ret_addr = is_bfin_call(ins_addr);
 print:
            if (!j && stack == (unsigned long *)addr)
                printk("[%08x]", *addr);
            else if (ret_addr)
                if (j) {
                    decode_address(buf, (unsigned int)*addr);
                    if (frame == addr) {
                        printk(KERN_NOTICE "   frame %2i : %s\n", frame_no, buf);
                        continue;
                    }
                    printk(KERN_NOTICE "    address : %s\n", buf);
                } else
                    printk("<%08x>", *addr);
            else if (fp == addr) {
                if (j)
                    frame = addr+1;
                else
                    printk("(%08x)", *addr);

                fp = (unsigned int *)*addr;
                frame_no++;

            } else if (!j)
                printk(" %08x ", *addr);
        }
        if (!j)
            printk("\n");
    }
#endif
}
EXPORT_SYMBOL(show_stack);

void dump_stack(void)
{
    unsigned long stack;
#ifdef CONFIG_DEBUG_BFIN_HWTRACE_ON
    int tflags;
#endif
    trace_buffer_save(tflags);
    dump_bfin_trace_buffer();
    show_stack(current, &stack);
    trace_buffer_restore(tflags);
}
EXPORT_SYMBOL(dump_stack);