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/memblock.h>
  17#include <asm/code-patching.h>
  18#include <asm/kdump.h>
  19#include <asm/prom.h>
  20#include <asm/firmware.h>
  21#include <asm/uaccess.h>
  22#include <asm/rtas.h>
  23
  24#ifdef DEBUG
  25#include <asm/udbg.h>
  26#define DBG(fmt...) udbg_printf(fmt)
  27#else
  28#define DBG(fmt...)
  29#endif
  30
  31#ifndef CONFIG_NONSTATIC_KERNEL
  32void __init reserve_kdump_trampoline(void)
  33{
  34        memblock_reserve(0, KDUMP_RESERVE_LIMIT);
  35}
  36
  37static void __init create_trampoline(unsigned long addr)
  38{
  39        unsigned int *p = (unsigned int *)addr;
  40
  41        /* The maximum range of a single instruction branch, is the current
  42         * instruction's address + (32 MB - 4) bytes. For the trampoline we
  43         * need to branch to current address + 32 MB. So we insert a nop at
  44         * the trampoline address, then the next instruction (+ 4 bytes)
  45         * does a branch to (32 MB - 4). The net effect is that when we
  46         * branch to "addr" we jump to ("addr" + 32 MB). Although it requires
  47         * two instructions it doesn't require any registers.
  48         */
  49        patch_instruction(p, PPC_INST_NOP);
  50        patch_branch(++p, addr + PHYSICAL_START, 0);
  51}
  52
  53void __init setup_kdump_trampoline(void)
  54{
  55        unsigned long i;
  56
  57        DBG(" -> setup_kdump_trampoline()\n");
  58
  59        for (i = KDUMP_TRAMPOLINE_START; i < KDUMP_TRAMPOLINE_END; i += 8) {
  60                create_trampoline(i);
  61        }
  62
  63#ifdef CONFIG_PPC_PSERIES
  64        create_trampoline(__pa(system_reset_fwnmi) - PHYSICAL_START);
  65        create_trampoline(__pa(machine_check_fwnmi) - PHYSICAL_START);
  66#endif /* CONFIG_PPC_PSERIES */
  67
  68        DBG(" <- setup_kdump_trampoline()\n");
  69}
  70#endif /* CONFIG_NONSTATIC_KERNEL */
  71
  72static int __init parse_savemaxmem(char *p)
  73{
  74        if (p)
  75                saved_max_pfn = (memparse(p, &p) >> PAGE_SHIFT) - 1;
  76
  77        return 1;
  78}
  79__setup("savemaxmem=", parse_savemaxmem);
  80
  81
  82static size_t copy_oldmem_vaddr(void *vaddr, char *buf, size_t csize,
  83                               unsigned long offset, int userbuf)
  84{
  85        if (userbuf) {
  86                if (copy_to_user((char __user *)buf, (vaddr + offset), csize))
  87                        return -EFAULT;
  88        } else
  89                memcpy(buf, (vaddr + offset), csize);
  90
  91        return csize;
  92}
  93
  94/**
  95 * copy_oldmem_page - copy one page from "oldmem"
  96 * @pfn: page frame number to be copied
  97 * @buf: target memory address for the copy; this can be in kernel address
  98 *      space or user address space (see @userbuf)
  99 * @csize: number of bytes to copy
 100 * @offset: offset in bytes into the page (based on pfn) to begin the copy
 101 * @userbuf: if set, @buf is in user address space, use copy_to_user(),
 102 *      otherwise @buf is in kernel address space, use memcpy().
 103 *
 104 * Copy a page from "oldmem". For this page, there is no pte mapped
 105 * in the current kernel. We stitch up a pte, similar to kmap_atomic.
 106 */
 107ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
 108                        size_t csize, unsigned long offset, int userbuf)
 109{
 110        void  *vaddr;
 111
 112        if (!csize)
 113                return 0;
 114
 115        csize = min_t(size_t, csize, PAGE_SIZE);
 116
 117        if ((min_low_pfn < pfn) && (pfn < max_pfn)) {
 118                vaddr = __va(pfn << PAGE_SHIFT);
 119                csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
 120        } else {
 121                vaddr = __ioremap(pfn << PAGE_SHIFT, PAGE_SIZE, 0);
 122                csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
 123                iounmap(vaddr);
 124        }
 125
 126        return csize;
 127}
 128
 129#ifdef CONFIG_PPC_RTAS
 130/*
 131 * The crashkernel region will almost always overlap the RTAS region, so
 132 * we have to be careful when shrinking the crashkernel region.
 133 */
 134void crash_free_reserved_phys_range(unsigned long begin, unsigned long end)
 135{
 136        unsigned long addr;
 137        const u32 *basep, *sizep;
 138        unsigned int rtas_start = 0, rtas_end = 0;
 139
 140        basep = of_get_property(rtas.dev, "linux,rtas-base", NULL);
 141        sizep = of_get_property(rtas.dev, "rtas-size", NULL);
 142
 143        if (basep && sizep) {
 144                rtas_start = *basep;
 145                rtas_end = *basep + *sizep;
 146        }
 147
 148        for (addr = begin; addr < end; addr += PAGE_SIZE) {
 149                /* Does this page overlap with the RTAS region? */
 150                if (addr <= rtas_end && ((addr + PAGE_SIZE) > rtas_start))
 151                        continue;
 152
 153                ClearPageReserved(pfn_to_page(addr >> PAGE_SHIFT));
 154                init_page_count(pfn_to_page(addr >> PAGE_SHIFT));
 155                free_page((unsigned long)__va(addr));
 156                totalram_pages++;
 157        }
 158}
 159#endif
 160