arch/powerpc/kernel/crash_dump.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Routines for doing kexec-based kdump.
   4  *
   5  * Copyright (C) 2005, IBM Corp.
   6  *
   7  * Created by: Michael Ellerman
   8  */
   9
  10 #undef DEBUG
  11
  12 #include <linux/crash_dump.h>
  13 #include <linux/io.h>
  14 #include <linux/memblock.h>
  15 #include <asm/code-patching.h>
  16 #include <asm/kdump.h>
  17 #include <asm/prom.h>
  18 #include <asm/firmware.h>
  19 #include <linux/uaccess.h>
  20 #include <asm/rtas.h>
  21
  22 #ifdef DEBUG
  23 #include <asm/udbg.h>
  24 #define DBG(fmt...) udbg_printf(fmt)
  25 #else
  26 #define DBG(fmt...)
  27 #endif
  28
  29 #ifndef CONFIG_NONSTATIC_KERNEL
  30 void __init reserve_kdump_trampoline(void)
  31 {
  32         memblock_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_INST_NOP);
  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 #endif /* CONFIG_NONSTATIC_KERNEL */
  69
  70 static size_t copy_oldmem_vaddr(void *vaddr, char *buf, size_t csize,
  71                                unsigned long offset, int userbuf)
  72 {
  73         if (userbuf) {
  74                 if (copy_to_user((char __user *)buf, (vaddr + offset), csize))
  75                         return -EFAULT;
  76         } else
  77                 memcpy(buf, (vaddr + offset), csize);
  78
  79         return csize;
  80 }
  81
  82 /**
  83  * copy_oldmem_page - copy one page from "oldmem"
  84  * @pfn: page frame number to be copied
  85  * @buf: target memory address for the copy; this can be in kernel address
  86  *      space or user address space (see @userbuf)
  87  * @csize: number of bytes to copy
  88  * @offset: offset in bytes into the page (based on pfn) to begin the copy
  89  * @userbuf: if set, @buf is in user address space, use copy_to_user(),
  90  *      otherwise @buf is in kernel address space, use memcpy().
  91  *
  92  * Copy a page from "oldmem". For this page, there is no pte mapped
  93  * in the current kernel. We stitch up a pte, similar to kmap_atomic.
  94  */
  95 ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
  96                         size_t csize, unsigned long offset, int userbuf)
  97 {
  98         void  *vaddr;
  99         phys_addr_t paddr;
 100
 101         if (!csize)
 102                 return 0;
 103
 104         csize = min_t(size_t, csize, PAGE_SIZE);
 105         paddr = pfn << PAGE_SHIFT;
 106
 107         if (memblock_is_region_memory(paddr, csize)) {
 108                 vaddr = __va(paddr);
 109                 csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
 110         } else {
 111                 vaddr = ioremap_cache(paddr, PAGE_SIZE);
 112                 csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
 113                 iounmap(vaddr);
 114         }
 115
 116         return csize;
 117 }
 118
 119 #ifdef CONFIG_PPC_RTAS
 120 /*
 121  * The crashkernel region will almost always overlap the RTAS region, so
 122  * we have to be careful when shrinking the crashkernel region.
 123  */
 124 void crash_free_reserved_phys_range(unsigned long begin, unsigned long end)
 125 {
 126         unsigned long addr;
 127         const __be32 *basep, *sizep;
 128         unsigned int rtas_start = 0, rtas_end = 0;
 129
 130         basep = of_get_property(rtas.dev, "linux,rtas-base", NULL);
 131         sizep = of_get_property(rtas.dev, "rtas-size", NULL);
 132
 133         if (basep && sizep) {
 134                 rtas_start = be32_to_cpup(basep);
 135                 rtas_end = rtas_start + be32_to_cpup(sizep);
 136         }
 137
 138         for (addr = begin; addr < end; addr += PAGE_SIZE) {
 139                 /* Does this page overlap with the RTAS region? */
 140                 if (addr <= rtas_end && ((addr + PAGE_SIZE) > rtas_start))
 141                         continue;
 142
 143                 free_reserved_page(pfn_to_page(addr >> PAGE_SHIFT));
 144         }
 145 }
 146 #endif