LXR linux/arch/powerpc/kernel/crash

   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
  31void __init reserve_kdump_trampoline(void)
  32{
  33        memblock_reserve(0, KDUMP_RESERVE_LIMIT);
  34}
  35
  36static void __init create_trampoline(unsigned long addr)
  37{
  38        u32 *p = (u32 *)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_RAW_NOP()));
  49        patch_branch(p + 1, addr + PHYSICAL_START, 0);
  50}
  51
  52void __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
  71static 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 */
  96ssize_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 */
 125void 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
 148