LXR linux/arch/x86/kernel/crash_dump

   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/uaccess.h>
  12#include <linux/io.h>
  13
  14static ssize_t __copy_oldmem_page(unsigned long pfn, char *buf, size_t csize,
  15                                  unsigned long offset, int userbuf,
  16                                  bool encrypted)
  17{
  18        void  *vaddr;
  19
  20        if (!csize)
  21                return 0;
  22
  23        if (encrypted)
  24                vaddr = (__force void *)ioremap_encrypted(pfn << PAGE_SHIFT, PAGE_SIZE);
  25        else
  26                vaddr = (__force void *)ioremap_cache(pfn << PAGE_SHIFT, PAGE_SIZE);
  27
  28        if (!vaddr)
  29                return -ENOMEM;
  30
  31        if (userbuf) {
  32                if (copy_to_user((void __user *)buf, vaddr + offset, csize)) {
  33                        iounmap((void __iomem *)vaddr);
  34                        return -EFAULT;
  35                }
  36        } else
  37                memcpy(buf, vaddr + offset, csize);
  38
  39        set_iounmap_nonlazy();
  40        iounmap((void __iomem *)vaddr);
  41        return csize;
  42}
  43
  44/**
  45 * copy_oldmem_page - copy one page of memory
  46 * @pfn: page frame number to be copied
  47 * @buf: target memory address for the copy; this can be in kernel address
  48 *      space or user address space (see @userbuf)
  49 * @csize: number of bytes to copy
  50 * @offset: offset in bytes into the page (based on pfn) to begin the copy
  51 * @userbuf: if set, @buf is in user address space, use copy_to_user(),
  52 *      otherwise @buf is in kernel address space, use memcpy().
  53 *
  54 * Copy a page from the old kernel's memory. For this page, there is no pte
  55 * mapped in the current kernel. We stitch up a pte, similar to kmap_atomic.
  56 */
  57ssize_t copy_oldmem_page(unsigned long pfn, char *buf, size_t csize,
  58                         unsigned long offset, int userbuf)
  59{
  60        return __copy_oldmem_page(pfn, buf, csize, offset, userbuf, false);
  61}
  62
  63/**
  64 * copy_oldmem_page_encrypted - same as copy_oldmem_page() above but ioremap the
  65 * memory with the encryption mask set to accommodate kdump on SME-enabled
  66 * machines.
  67 */
  68ssize_t copy_oldmem_page_encrypted(unsigned long pfn, char *buf, size_t csize,
  69                                   unsigned long offset, int userbuf)
  70{
  71        return __copy_oldmem_page(pfn, buf, csize, offset, userbuf, true);
  72}
  73
  74ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos)
  75{
  76        return read_from_oldmem(buf, count, ppos, 0, sev_active());
  77}
  78