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 #ifndef CONFIG_NONSTATIC_KERNEL
  32 void __init reserve_kdump_trampoline(void)
  33 {
  34         memblock_reserve(0, KDUMP_RESERVE_LIMIT);
  35 }
  36
  37 static 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
  53 void __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
  72 static 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
  82 static 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  */
 107 ssize_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  */
 134 void 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                 free_reserved_page(pfn_to_page(addr >> PAGE_SHIFT));
 154         }
 155 }
 156 #endif