LXR linux/arch/powerpc/kernel/crash

   1/*
   2 * Routines for doing kexec-based kdump.
   3 *
   4 * Copyright (C) 2005, IBM Corp.
   5 *
   6 * Created by: Michael Ellerman
   7 *
   8 * This source code is licensed under the GNU General Public License,
   9 * Version 2.  See the file COPYING for more details.
  10 */
  11
  12#undef DEBUG
  13
  14#include <linux/crash_dump.h>
  15#include <linux/bootmem.h>
  16#include <linux/io.h>
  17#include <linux/memblock.h>
  18#include <asm/code-patching.h>
  19#include <asm/kdump.h>
  20#include <asm/prom.h>
  21#include <asm/firmware.h>
  22#include <asm/uaccess.h>
  23#include <asm/rtas.h>
  24
  25#ifdef DEBUG
  26#include <asm/udbg.h>
  27#define DBG(fmt...) udbg_printf(fmt)
  28#else
  29#define DBG(fmt...)
  30#endif
  31
  32#ifndef CONFIG_NONSTATIC_KERNEL
  33void __init reserve_kdump_trampoline(void)
  34{
  35        memblock_reserve(0, KDUMP_RESERVE_LIMIT);
  36}
  37
  38static void __init create_trampoline(unsigned long addr)
  39{
  40        unsigned int *p = (unsigned int *)addr;
  41
  42        /* The maximum range of a single instruction branch, is the current
  43         * instruction's address + (32 MB - 4) bytes. For the trampoline we
  44         * need to branch to current address + 32 MB. So we insert a nop at
  45         * the trampoline address, then the next instruction (+ 4 bytes)
  46         * does a branch to (32 MB - 4). The net effect is that when we
  47         * branch to "addr" we jump to ("addr" + 32 MB). Although it requires
  48         * two instructions it doesn't require any registers.
  49         */
  50        patch_instruction(p, PPC_INST_NOP);
  51        patch_branch(++p, addr + PHYSICAL_START, 0);
  52}
  53
  54void __init setup_kdump_trampoline(void)
  55{
  56        unsigned long i;
  57
  58        DBG(" -> setup_kdump_trampoline()\n");
  59
  60        for (i = KDUMP_TRAMPOLINE_START; i < KDUMP_TRAMPOLINE_END; i += 8) {
  61                create_trampoline(i);
  62        }
  63
  64#ifdef CONFIG_PPC_PSERIES
  65        create_trampoline(__pa(system_reset_fwnmi) - PHYSICAL_START);
  66        create_trampoline(__pa(machine_check_fwnmi) - PHYSICAL_START);
  67#endif /* CONFIG_PPC_PSERIES */
  68
  69        DBG(" <- setup_kdump_trampoline()\n");
  70}
  71#endif /* CONFIG_NONSTATIC_KERNEL */
  72
  73static size_t copy_oldmem_vaddr(void *vaddr, char *buf, size_t csize,
  74                               unsigned long offset, int userbuf)
  75{
  76        if (userbuf) {
  77                if (copy_to_user((char __user *)buf, (vaddr + offset), csize))
  78                        return -EFAULT;
  79        } else
  80                memcpy(buf, (vaddr + offset), csize);
  81
  82        return csize;
  83}
  84
  85/**
  86 * copy_oldmem_page - copy one page from "oldmem"
  87 * @pfn: page frame number to be copied
  88 * @buf: target memory address for the copy; this can be in kernel address
  89 *      space or user address space (see @userbuf)
  90 * @csize: number of bytes to copy
  91 * @offset: offset in bytes into the page (based on pfn) to begin the copy
  92 * @userbuf: if set, @buf is in user address space, use copy_to_user(),
  93 *      otherwise @buf is in kernel address space, use memcpy().
  94 *
  95 * Copy a page from "oldmem". For this page, there is no pte mapped
  96 * in the current kernel. We stitch up a pte, similar to kmap_atomic.
  97 */
  98ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
  99                        size_t csize, unsigned long offset, int userbuf)
 100{
 101        void  *vaddr;
 102        phys_addr_t paddr;
 103
 104        if (!csize)
 105                return 0;
 106
 107        csize = min_t(size_t, csize, PAGE_SIZE);
 108        paddr = pfn << PAGE_SHIFT;
 109
 110        if (memblock_is_region_memory(paddr, csize)) {
 111                vaddr = __va(paddr);
 112                csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
 113        } else {
 114                vaddr = __ioremap(paddr, PAGE_SIZE, 0);
 115                csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
 116                iounmap(vaddr);
 117        }
 118
 119        return csize;
 120}
 121
 122#ifdef CONFIG_PPC_RTAS
 123/*
 124 * The crashkernel region will almost always overlap the RTAS region, so
 125 * we have to be careful when shrinking the crashkernel region.
 126 */
 127void crash_free_reserved_phys_range(unsigned long begin, unsigned long end)
 128{
 129        unsigned long addr;
 130        const __be32 *basep, *sizep;
 131        unsigned int rtas_start = 0, rtas_end = 0;
 132
 133        basep = of_get_property(rtas.dev, "linux,rtas-base", NULL);
 134        sizep = of_get_property(rtas.dev, "rtas-size", NULL);
 135
 136        if (basep && sizep) {
 137                rtas_start = be32_to_cpup(basep);
 138                rtas_end = rtas_start + be32_to_cpup(sizep);
 139        }
 140
 141        for (addr = begin; addr < end; addr += PAGE_SIZE) {
 142                /* Does this page overlap with the RTAS region? */
 143                if (addr <= rtas_end && ((addr + PAGE_SIZE) > rtas_start))
 144                        continue;
 145
 146                free_reserved_page(pfn_to_page(addr >> PAGE_SHIFT));
 147        }
 148}
 149#endif
 150