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/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 /* Stores the physical address of elf header of crash image. */
  32 unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX;
  33
  34 #ifndef CONFIG_RELOCATABLE
  35 void __init reserve_kdump_trampoline(void)
  36 {
  37         memblock_reserve(0, KDUMP_RESERVE_LIMIT);
  38 }
  39
  40 static void __init create_trampoline(unsigned long addr)
  41 {
  42         unsigned int *p = (unsigned int *)addr;
  43
  44         /* The maximum range of a single instruction branch, is the current
  45          * instruction's address + (32 MB - 4) bytes. For the trampoline we
  46          * need to branch to current address + 32 MB. So we insert a nop at
  47          * the trampoline address, then the next instruction (+ 4 bytes)
  48          * does a branch to (32 MB - 4). The net effect is that when we
  49          * branch to "addr" we jump to ("addr" + 32 MB). Although it requires
  50          * two instructions it doesn't require any registers.
  51          */
  52         patch_instruction(p, PPC_INST_NOP);
  53         patch_branch(++p, addr + PHYSICAL_START, 0);
  54 }
  55
  56 void __init setup_kdump_trampoline(void)
  57 {
  58         unsigned long i;
  59
  60         DBG(" -> setup_kdump_trampoline()\n");
  61
  62         for (i = KDUMP_TRAMPOLINE_START; i < KDUMP_TRAMPOLINE_END; i += 8) {
  63                 create_trampoline(i);
  64         }
  65
  66 #ifdef CONFIG_PPC_PSERIES
  67         create_trampoline(__pa(system_reset_fwnmi) - PHYSICAL_START);
  68         create_trampoline(__pa(machine_check_fwnmi) - PHYSICAL_START);
  69 #endif /* CONFIG_PPC_PSERIES */
  70
  71         DBG(" <- setup_kdump_trampoline()\n");
  72 }
  73 #endif /* CONFIG_RELOCATABLE */
  74
  75 /*
  76  * Note: elfcorehdr_addr is not just limited to vmcore. It is also used by
  77  * is_kdump_kernel() to determine if we are booting after a panic. Hence
  78  * ifdef it under CONFIG_CRASH_DUMP and not CONFIG_PROC_VMCORE.
  79  */
  80 static int __init parse_elfcorehdr(char *p)
  81 {
  82         if (p)
  83                 elfcorehdr_addr = memparse(p, &p);
  84
  85         return 1;
  86 }
  87 __setup("elfcorehdr=", parse_elfcorehdr);
  88
  89 static int __init parse_savemaxmem(char *p)
  90 {
  91         if (p)
  92                 saved_max_pfn = (memparse(p, &p) >> PAGE_SHIFT) - 1;
  93
  94         return 1;
  95 }
  96 __setup("savemaxmem=", parse_savemaxmem);
  97
  98
  99 static size_t copy_oldmem_vaddr(void *vaddr, char *buf, size_t csize,
 100                                unsigned long offset, int userbuf)
 101 {
 102         if (userbuf) {
 103                 if (copy_to_user((char __user *)buf, (vaddr + offset), csize))
 104                         return -EFAULT;
 105         } else
 106                 memcpy(buf, (vaddr + offset), csize);
 107
 108         return csize;
 109 }
 110
 111 /**
 112  * copy_oldmem_page - copy one page from "oldmem"
 113  * @pfn: page frame number to be copied
 114  * @buf: target memory address for the copy; this can be in kernel address
 115  *      space or user address space (see @userbuf)
 116  * @csize: number of bytes to copy
 117  * @offset: offset in bytes into the page (based on pfn) to begin the copy
 118  * @userbuf: if set, @buf is in user address space, use copy_to_user(),
 119  *      otherwise @buf is in kernel address space, use memcpy().
 120  *
 121  * Copy a page from "oldmem". For this page, there is no pte mapped
 122  * in the current kernel. We stitch up a pte, similar to kmap_atomic.
 123  */
 124 ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
 125                         size_t csize, unsigned long offset, int userbuf)
 126 {
 127         void  *vaddr;
 128
 129         if (!csize)
 130                 return 0;
 131
 132         csize = min_t(size_t, csize, PAGE_SIZE);
 133
 134         if ((min_low_pfn < pfn) && (pfn < max_pfn)) {
 135                 vaddr = __va(pfn << PAGE_SHIFT);
 136                 csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
 137         } else {
 138                 vaddr = __ioremap(pfn << PAGE_SHIFT, PAGE_SIZE, 0);
 139                 csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
 140                 iounmap(vaddr);
 141         }
 142
 143         return csize;
 144 }
 145
 146 #ifdef CONFIG_PPC_RTAS
 147 /*
 148  * The crashkernel region will almost always overlap the RTAS region, so
 149  * we have to be careful when shrinking the crashkernel region.
 150  */
 151 void crash_free_reserved_phys_range(unsigned long begin, unsigned long end)
 152 {
 153         unsigned long addr;
 154         const u32 *basep, *sizep;
 155         unsigned int rtas_start = 0, rtas_end = 0;
 156
 157         basep = of_get_property(rtas.dev, "linux,rtas-base", NULL);
 158         sizep = of_get_property(rtas.dev, "rtas-size", NULL);
 159
 160         if (basep && sizep) {
 161                 rtas_start = *basep;
 162                 rtas_end = *basep + *sizep;
 163         }
 164
 165         for (addr = begin; addr < end; addr += PAGE_SIZE) {
 166                 /* Does this page overlap with the RTAS region? */
 167                 if (addr <= rtas_end && ((addr + PAGE_SIZE) > rtas_start))
 168                         continue;
 169
 170                 ClearPageReserved(pfn_to_page(addr >> PAGE_SHIFT));
 171                 init_page_count(pfn_to_page(addr >> PAGE_SHIFT));
 172                 free_page((unsigned long)__va(addr));
 173                 totalram_pages++;
 174         }
 175 }
 176 #endif