LXR linux/arch/ia64/kernel/crash

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 *      kernel/crash_dump.c - Memory preserving reboot related code.
   4 *
   5 *      Created by: Simon Horman <horms@verge.net.au>
   6 *      Original code moved from kernel/crash.c
   7 *      Original code comment copied from the i386 version of this file
   8 */
   9
  10#include <linux/errno.h>
  11#include <linux/types.h>
  12#include <linux/crash_dump.h>
  13
  14#include <asm/page.h>
  15#include <linux/uaccess.h>
  16
  17/**
  18 * copy_oldmem_page - copy one page from "oldmem"
  19 * @pfn: page frame number to be copied
  20 * @buf: target memory address for the copy; this can be in kernel address
  21 *      space or user address space (see @userbuf)
  22 * @csize: number of bytes to copy
  23 * @offset: offset in bytes into the page (based on pfn) to begin the copy
  24 * @userbuf: if set, @buf is in user address space, use copy_to_user(),
  25 *      otherwise @buf is in kernel address space, use memcpy().
  26 *
  27 * Copy a page from "oldmem". For this page, there is no pte mapped
  28 * in the current kernel. We stitch up a pte, similar to kmap_atomic.
  29 *
  30 * Calling copy_to_user() in atomic context is not desirable. Hence first
  31 * copying the data to a pre-allocated kernel page and then copying to user
  32 * space in non-atomic context.
  33 */
  34ssize_t
  35copy_oldmem_page(unsigned long pfn, char *buf,
  36                size_t csize, unsigned long offset, int userbuf)
  37{
  38        void  *vaddr;
  39
  40        if (!csize)
  41                return 0;
  42        vaddr = __va(pfn<<PAGE_SHIFT);
  43        if (userbuf) {
  44                if (copy_to_user(buf, (vaddr + offset), csize)) {
  45                        return -EFAULT;
  46                }
  47        } else
  48                memcpy(buf, (vaddr + offset), csize);
  49        return csize;
  50}
  51
  52