arch/x86/kernel/crash_dump_64.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *      Memory preserving reboot related code.
   4  *
   5  *      Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
   6  *      Copyright (C) IBM Corporation, 2004. All rights reserved
   7  */
   8
   9 #include <linux/errno.h>
  10 #include <linux/crash_dump.h>
  11 #include <linux/uio.h>
  12 #include <linux/io.h>
  13 #include <linux/cc_platform.h>
  14
  15 static ssize_t __copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
  16                                   size_t csize, unsigned long offset,
  17                                   bool encrypted)
  18 {
  19         void  *vaddr;
  20
  21         if (!csize)
  22                 return 0;
  23
  24         if (encrypted)
  25                 vaddr = (__force void *)ioremap_encrypted(pfn << PAGE_SHIFT, PAGE_SIZE);
  26         else
  27                 vaddr = (__force void *)ioremap_cache(pfn << PAGE_SHIFT, PAGE_SIZE);
  28
  29         if (!vaddr)
  30                 return -ENOMEM;
  31
  32         csize = copy_to_iter(vaddr + offset, csize, iter);
  33
  34         iounmap((void __iomem *)vaddr);
  35         return csize;
  36 }
  37
  38 ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, size_t csize,
  39                          unsigned long offset)
  40 {
  41         return __copy_oldmem_page(iter, pfn, csize, offset, false);
  42 }
  43
  44 /*
  45  * copy_oldmem_page_encrypted - same as copy_oldmem_page() above but ioremap the
  46  * memory with the encryption mask set to accommodate kdump on SME-enabled
  47  * machines.
  48  */
  49 ssize_t copy_oldmem_page_encrypted(struct iov_iter *iter, unsigned long pfn,
  50                                    size_t csize, unsigned long offset)
  51 {
  52         return __copy_oldmem_page(iter, pfn, csize, offset, true);
  53 }
  54
  55 ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos)
  56 {
  57         struct kvec kvec = { .iov_base = buf, .iov_len = count };
  58         struct iov_iter iter;
  59
  60         iov_iter_kvec(&iter, ITER_DEST, &kvec, 1, count);
  61
  62         return read_from_oldmem(&iter, count, ppos,
  63                                 cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT));
  64 }