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 #include <asm/inst.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 #ifndef CONFIG_NONSTATIC_KERNEL
  31 void __init reserve_kdump_trampoline(void)
  32 {
  33         memblock_reserve(0, KDUMP_RESERVE_LIMIT);
  34 }
  35
  36 static void __init create_trampoline(unsigned long addr)
  37 {
  38         struct ppc_inst *p = (struct ppc_inst *)addr;
  39
  40         /* The maximum range of a single instruction branch, is the current
  41          * instruction's address + (32 MB - 4) bytes. For the trampoline we
  42          * need to branch to current address + 32 MB. So we insert a nop at
  43          * the trampoline address, then the next instruction (+ 4 bytes)
  44          * does a branch to (32 MB - 4). The net effect is that when we
  45          * branch to "addr" we jump to ("addr" + 32 MB). Although it requires
  46          * two instructions it doesn't require any registers.
  47          */
  48         patch_instruction(p, ppc_inst(PPC_INST_NOP));
  49         patch_branch((void *)p + 4, addr + PHYSICAL_START, 0);
  50 }
  51
  52 void __init setup_kdump_trampoline(void)
  53 {
  54         unsigned long i;
  55
  56         DBG(" -> setup_kdump_trampoline()\n");
  57
  58         for (i = KDUMP_TRAMPOLINE_START; i < KDUMP_TRAMPOLINE_END; i += 8) {
  59                 create_trampoline(i);
  60         }
  61
  62 #ifdef CONFIG_PPC_PSERIES
  63         create_trampoline(__pa(system_reset_fwnmi) - PHYSICAL_START);
  64         create_trampoline(__pa(machine_check_fwnmi) - PHYSICAL_START);
  65 #endif /* CONFIG_PPC_PSERIES */
  66
  67         DBG(" <- setup_kdump_trampoline()\n");
  68 }
  69 #endif /* CONFIG_NONSTATIC_KERNEL */
  70
  71 static size_t copy_oldmem_vaddr(void *vaddr, char *buf, size_t csize,
  72                                unsigned long offset, int userbuf)
  73 {
  74         if (userbuf) {
  75                 if (copy_to_user((char __user *)buf, (vaddr + offset), csize))
  76                         return -EFAULT;
  77         } else
  78                 memcpy(buf, (vaddr + offset), csize);
  79
  80         return csize;
  81 }
  82
  83 /**
  84  * copy_oldmem_page - copy one page from "oldmem"
  85  * @pfn: page frame number to be copied
  86  * @buf: target memory address for the copy; this can be in kernel address
  87  *      space or user address space (see @userbuf)
  88  * @csize: number of bytes to copy
  89  * @offset: offset in bytes into the page (based on pfn) to begin the copy
  90  * @userbuf: if set, @buf is in user address space, use copy_to_user(),
  91  *      otherwise @buf is in kernel address space, use memcpy().
  92  *
  93  * Copy a page from "oldmem". For this page, there is no pte mapped
  94  * in the current kernel. We stitch up a pte, similar to kmap_atomic.
  95  */
  96 ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
  97                         size_t csize, unsigned long offset, int userbuf)
  98 {
  99         void  *vaddr;
 100         phys_addr_t paddr;
 101
 102         if (!csize)
 103                 return 0;
 104
 105         csize = min_t(size_t, csize, PAGE_SIZE);
 106         paddr = pfn << PAGE_SHIFT;
 107
 108         if (memblock_is_region_memory(paddr, csize)) {
 109                 vaddr = __va(paddr);
 110                 csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
 111         } else {
 112                 vaddr = ioremap_cache(paddr, PAGE_SIZE);
 113                 csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
 114                 iounmap(vaddr);
 115         }
 116
 117         return csize;
 118 }
 119
 120 #ifdef CONFIG_PPC_RTAS
 121 /*
 122  * The crashkernel region will almost always overlap the RTAS region, so
 123  * we have to be careful when shrinking the crashkernel region.
 124  */
 125 void crash_free_reserved_phys_range(unsigned long begin, unsigned long end)
 126 {
 127         unsigned long addr;
 128         const __be32 *basep, *sizep;
 129         unsigned int rtas_start = 0, rtas_end = 0;
 130
 131         basep = of_get_property(rtas.dev, "linux,rtas-base", NULL);
 132         sizep = of_get_property(rtas.dev, "rtas-size", NULL);
 133
 134         if (basep && sizep) {
 135                 rtas_start = be32_to_cpup(basep);
 136                 rtas_end = rtas_start + be32_to_cpup(sizep);
 137         }
 138
 139         for (addr = begin; addr < end; addr += PAGE_SIZE) {
 140                 /* Does this page overlap with the RTAS region? */
 141                 if (addr <= rtas_end && ((addr + PAGE_SIZE) > rtas_start))
 142                         continue;
 143
 144                 free_reserved_page(pfn_to_page(addr >> PAGE_SHIFT));
 145         }
 146 }
 147 #endif