arch/arm64/kernel/crash_dump.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Routines for doing kexec-based kdump
   4  *
   5  * Copyright (C) 2017 Linaro Limited
   6  * Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
   7  */
   8
   9 #include <linux/crash_dump.h>
  10 #include <linux/errno.h>
  11 #include <linux/io.h>
  12 #include <linux/uio.h>
  13 #include <asm/memory.h>
  14
  15 ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
  16                          size_t csize, unsigned long offset)
  17 {
  18         void *vaddr;
  19
  20         if (!csize)
  21                 return 0;
  22
  23         vaddr = memremap(__pfn_to_phys(pfn), PAGE_SIZE, MEMREMAP_WB);
  24         if (!vaddr)
  25                 return -ENOMEM;
  26
  27         csize = copy_to_iter(vaddr + offset, csize, iter);
  28
  29         memunmap(vaddr);
  30
  31         return csize;
  32 }
  33
  34 /**
  35  * elfcorehdr_read - read from ELF core header
  36  * @buf: buffer where the data is placed
  37  * @count: number of bytes to read
  38  * @ppos: address in the memory
  39  *
  40  * This function reads @count bytes from elf core header which exists
  41  * on crash dump kernel's memory.
  42  */
  43 ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos)
  44 {
  45         memcpy(buf, phys_to_virt((phys_addr_t)*ppos), count);
  46         *ppos += count;
  47
  48         return count;
  49 }