arch/powerpc/kernel/crash_dump.c

   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/lmb.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
  23 #ifdef DEBUG
  24 #include <asm/udbg.h>
  25 #define DBG(fmt...) udbg_printf(fmt)
  26 #else
  27 #define DBG(fmt...)
  28 #endif
  29
  30 void __init reserve_kdump_trampoline(void)
  31 {
  32         lmb_reserve(0, KDUMP_RESERVE_LIMIT);
  33 }
  34
  35 static void __init create_trampoline(unsigned long addr)
  36 {
  37         unsigned int *p = (unsigned int *)addr;
  38
  39         /* The maximum range of a single instruction branch, is the current
  40          * instruction's address + (32 MB - 4) bytes. For the trampoline we
  41          * need to branch to current address + 32 MB. So we insert a nop at
  42          * the trampoline address, then the next instruction (+ 4 bytes)
  43          * does a branch to (32 MB - 4). The net effect is that when we
  44          * branch to "addr" we jump to ("addr" + 32 MB). Although it requires
  45          * two instructions it doesn't require any registers.
  46          */
  47         patch_instruction(p, PPC_NOP_INSTR);
  48         patch_branch(++p, addr + PHYSICAL_START, 0);
  49 }
  50
  51 void __init setup_kdump_trampoline(void)
  52 {
  53         unsigned long i;
  54
  55         DBG(" -> setup_kdump_trampoline()\n");
  56
  57         for (i = KDUMP_TRAMPOLINE_START; i < KDUMP_TRAMPOLINE_END; i += 8) {
  58                 create_trampoline(i);
  59         }
  60
  61 #ifdef CONFIG_PPC_PSERIES
  62         create_trampoline(__pa(system_reset_fwnmi) - PHYSICAL_START);
  63         create_trampoline(__pa(machine_check_fwnmi) - PHYSICAL_START);
  64 #endif /* CONFIG_PPC_PSERIES */
  65
  66         DBG(" <- setup_kdump_trampoline()\n");
  67 }
  68
  69 #ifdef CONFIG_PROC_VMCORE
  70 static int __init parse_elfcorehdr(char *p)
  71 {
  72         if (p)
  73                 elfcorehdr_addr = memparse(p, &p);
  74
  75         return 1;
  76 }
  77 __setup("elfcorehdr=", parse_elfcorehdr);
  78 #endif
  79
  80 static int __init parse_savemaxmem(char *p)
  81 {
  82         if (p)
  83                 saved_max_pfn = (memparse(p, &p) >> PAGE_SHIFT) - 1;
  84
  85         return 1;
  86 }
  87 __setup("savemaxmem=", parse_savemaxmem);
  88
  89
  90 static size_t copy_oldmem_vaddr(void *vaddr, char *buf, size_t csize,
  91                                unsigned long offset, int userbuf)
  92 {
  93         if (userbuf) {
  94                 if (copy_to_user((char __user *)buf, (vaddr + offset), csize))
  95                         return -EFAULT;
  96         } else
  97                 memcpy(buf, (vaddr + offset), csize);
  98
  99         return csize;
 100 }
 101
 102 /**
 103  * copy_oldmem_page - copy one page from "oldmem"
 104  * @pfn: page frame number to be copied
 105  * @buf: target memory address for the copy; this can be in kernel address
 106  *      space or user address space (see @userbuf)
 107  * @csize: number of bytes to copy
 108  * @offset: offset in bytes into the page (based on pfn) to begin the copy
 109  * @userbuf: if set, @buf is in user address space, use copy_to_user(),
 110  *      otherwise @buf is in kernel address space, use memcpy().
 111  *
 112  * Copy a page from "oldmem". For this page, there is no pte mapped
 113  * in the current kernel. We stitch up a pte, similar to kmap_atomic.
 114  */
 115 ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
 116                         size_t csize, unsigned long offset, int userbuf)
 117 {
 118         void  *vaddr;
 119
 120         if (!csize)
 121                 return 0;
 122
 123         csize = min(csize, PAGE_SIZE);
 124
 125         if (pfn < max_pfn) {
 126                 vaddr = __va(pfn << PAGE_SHIFT);
 127                 csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
 128         } else {
 129                 vaddr = __ioremap(pfn << PAGE_SHIFT, PAGE_SIZE, 0);
 130                 csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
 131                 iounmap(vaddr);
 132         }
 133
 134         return csize;
 135 }