crash_dump.c

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/*
 * Routines for doing kexec-based kdump.
 *
 * Copyright (C) 2005, IBM Corp.
 *
 * Created by: Michael Ellerman
 *
 * This source code is licensed under the GNU General Public License,
 * Version 2.  See the file COPYING for more details.
 */

#undef DEBUG

#include <linux/crash_dump.h>
#include <linux/bootmem.h>
#include <linux/memblock.h>
#include <asm/code-patching.h>
#include <asm/kdump.h>
#include <asm/prom.h>
#include <asm/firmware.h>
#include <asm/uaccess.h>
#include <asm/rtas.h>

#ifdef DEBUG
#include <asm/udbg.h>
#define DBG(fmt...) udbg_printf(fmt)
#else
#define DBG(fmt...)
#endif

#ifndef CONFIG_NONSTATIC_KERNEL
void __init reserve_kdump_trampoline(void)
{
    memblock_reserve(0, KDUMP_RESERVE_LIMIT);
}

static void __init create_trampoline(unsigned long addr)
{
    unsigned int *p = (unsigned int *)addr;

    /* The maximum range of a single instruction branch, is the current
     * instruction's address + (32 MB - 4) bytes. For the trampoline we
     * need to branch to current address + 32 MB. So we insert a nop at
     * the trampoline address, then the next instruction (+ 4 bytes)
     * does a branch to (32 MB - 4). The net effect is that when we
     * branch to "addr" we jump to ("addr" + 32 MB). Although it requires
     * two instructions it doesn't require any registers.
     */
    patch_instruction(p, PPC_INST_NOP);
    patch_branch(++p, addr + PHYSICAL_START, 0);
}

void __init setup_kdump_trampoline(void)
{
    unsigned long i;

    DBG(" -> setup_kdump_trampoline()\n");

    for (i = KDUMP_TRAMPOLINE_START; i < KDUMP_TRAMPOLINE_END; i += 8) {
        create_trampoline(i);
    }

#ifdef CONFIG_PPC_PSERIES
    create_trampoline(__pa(system_reset_fwnmi) - PHYSICAL_START);
    create_trampoline(__pa(machine_check_fwnmi) - PHYSICAL_START);
#endif /* CONFIG_PPC_PSERIES */

    DBG(" <- setup_kdump_trampoline()\n");
}
#endif /* CONFIG_NONSTATIC_KERNEL */

static int __init parse_savemaxmem(char *p)
{
    if (p)
        saved_max_pfn = (memparse(p, &p) >> PAGE_SHIFT) - 1;

    return 1;
}
__setup("savemaxmem=", parse_savemaxmem);


static size_t copy_oldmem_vaddr(void *vaddr, char *buf, size_t csize,
                               unsigned long offset, int userbuf)
{
    if (userbuf) {
        if (copy_to_user((char __user *)buf, (vaddr + offset), csize))
            return -EFAULT;
    } else
        memcpy(buf, (vaddr + offset), csize);

    return csize;
}

ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
            size_t csize, unsigned long offset, int userbuf)
{
    void  *vaddr;

    if (!csize)
        return 0;

    csize = min_t(size_t, csize, PAGE_SIZE);

    if ((min_low_pfn < pfn) && (pfn < max_pfn)) {
        vaddr = __va(pfn << PAGE_SHIFT);
        csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
    } else {
        vaddr = __ioremap(pfn << PAGE_SHIFT, PAGE_SIZE, 0);
        csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
        iounmap(vaddr);
    }

    return csize;
}

#ifdef CONFIG_PPC_RTAS
/*
 * The crashkernel region will almost always overlap the RTAS region, so
 * we have to be careful when shrinking the crashkernel region.
 */
void crash_free_reserved_phys_range(unsigned long begin, unsigned long end)
{
    unsigned long addr;
    const u32 *basep, *sizep;
    unsigned int rtas_start = 0, rtas_end = 0;

    basep = of_get_property(rtas.dev, "linux,rtas-base", NULL);
    sizep = of_get_property(rtas.dev, "rtas-size", NULL);

    if (basep && sizep) {
        rtas_start = *basep;
        rtas_end = *basep + *sizep;
    }

    for (addr = begin; addr < end; addr += PAGE_SIZE) {
        /* Does this page overlap with the RTAS region? */
        if (addr <= rtas_end && ((addr + PAGE_SIZE) > rtas_start))
            continue;

        ClearPageReserved(pfn_to_page(addr >> PAGE_SHIFT));
        init_page_count(pfn_to_page(addr >> PAGE_SHIFT));
        free_page((unsigned long)__va(addr));
        totalram_pages++;
    }
}
#endif