LXR linux/arch/ia64/kernel/crash

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