LXR linux/arch/mips/kernel/crash

   1#include <linux/highmem.h>
   2#include <linux/bootmem.h>
   3#include <linux/crash_dump.h>
   4#include <asm/uaccess.h>
   5#include <linux/slab.h>
   6
   7static void *kdump_buf_page;
   8
   9/**
  10 * copy_oldmem_page - copy one page from "oldmem"
  11 * @pfn: page frame number to be copied
  12 * @buf: target memory address for the copy; this can be in kernel address
  13 *      space or user address space (see @userbuf)
  14 * @csize: number of bytes to copy
  15 * @offset: offset in bytes into the page (based on pfn) to begin the copy
  16 * @userbuf: if set, @buf is in user address space, use copy_to_user(),
  17 *      otherwise @buf is in kernel address space, use memcpy().
  18 *
  19 * Copy a page from "oldmem". For this page, there is no pte mapped
  20 * in the current kernel.
  21 *
  22 * Calling copy_to_user() in atomic context is not desirable. Hence first
  23 * copying the data to a pre-allocated kernel page and then copying to user
  24 * space in non-atomic context.
  25 */
  26ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
  27                         size_t csize, unsigned long offset, int userbuf)
  28{
  29        void  *vaddr;
  30
  31        if (!csize)
  32                return 0;
  33
  34        vaddr = kmap_atomic_pfn(pfn);
  35
  36        if (!userbuf) {
  37                memcpy(buf, (vaddr + offset), csize);
  38                kunmap_atomic(vaddr);
  39        } else {
  40                if (!kdump_buf_page) {
  41                        pr_warn("Kdump: Kdump buffer page not allocated\n");
  42
  43                        return -EFAULT;
  44                }
  45                copy_page(kdump_buf_page, vaddr);
  46                kunmap_atomic(vaddr);
  47                if (copy_to_user(buf, (kdump_buf_page + offset), csize))
  48                        return -EFAULT;
  49        }
  50
  51        return csize;
  52}
  53
  54static int __init kdump_buf_page_init(void)
  55{
  56        int ret = 0;
  57
  58        kdump_buf_page = kmalloc(PAGE_SIZE, GFP_KERNEL);
  59        if (!kdump_buf_page) {
  60                pr_warn("Kdump: Failed to allocate kdump buffer page\n");
  61                ret = -ENOMEM;
  62        }
  63
  64        return ret;
  65}
  66arch_initcall(kdump_buf_page_init);
  67