LXR linux/arch/arm64/kernel/crash

   1/*
   2 * Routines for doing kexec-based kdump
   3 *
   4 * Copyright (C) 2017 Linaro Limited
   5 * Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
   6 *
   7 * This program is free software; you can redistribute it and/or modify
   8 * it under the terms of the GNU General Public License version 2 as
   9 * published by the Free Software Foundation.
  10 */
  11
  12#include <linux/crash_dump.h>
  13#include <linux/errno.h>
  14#include <linux/io.h>
  15#include <linux/memblock.h>
  16#include <linux/uaccess.h>
  17#include <asm/memory.h>
  18
  19/**
  20 * copy_oldmem_page() - copy one page from old kernel memory
  21 * @pfn: page frame number to be copied
  22 * @buf: buffer where the copied page is placed
  23 * @csize: number of bytes to copy
  24 * @offset: offset in bytes into the page
  25 * @userbuf: if set, @buf is in a user address space
  26 *
  27 * This function copies one page from old kernel memory into buffer pointed by
  28 * @buf. If @buf is in userspace, set @userbuf to %1. Returns number of bytes
  29 * copied or negative error in case of failure.
  30 */
  31ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
  32                         size_t csize, unsigned long offset,
  33                         int userbuf)
  34{
  35        void *vaddr;
  36
  37        if (!csize)
  38                return 0;
  39
  40        vaddr = memremap(__pfn_to_phys(pfn), PAGE_SIZE, MEMREMAP_WB);
  41        if (!vaddr)
  42                return -ENOMEM;
  43
  44        if (userbuf) {
  45                if (copy_to_user((char __user *)buf, vaddr + offset, csize)) {
  46                        memunmap(vaddr);
  47                        return -EFAULT;
  48                }
  49        } else {
  50                memcpy(buf, vaddr + offset, csize);
  51        }
  52
  53        memunmap(vaddr);
  54
  55        return csize;
  56}
  57
  58/**
  59 * elfcorehdr_read - read from ELF core header
  60 * @buf: buffer where the data is placed
  61 * @csize: number of bytes to read
  62 * @ppos: address in the memory
  63 *
  64 * This function reads @count bytes from elf core header which exists
  65 * on crash dump kernel's memory.
  66 */
  67ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos)
  68{
  69        memcpy(buf, phys_to_virt((phys_addr_t)*ppos), count);
  70        return count;
  71}
  72