1 #include <linux/highmem.h>
2 #include <linux/bootmem.h>
3 #include <linux/crash_dump.h>
4 #include <asm/uaccess.h>
6 static int __init parse_savemaxmem(char *p)
9 saved_max_pfn = (memparse(p, &p) >> PAGE_SHIFT) - 1;
13 __setup("savemaxmem=", parse_savemaxmem);
16 static void *kdump_buf_page;
19 * copy_oldmem_page - copy one page from "oldmem"
20 * @pfn: page frame number to be copied
21 * @buf: target memory address for the copy; this can be in kernel address
22 * space or user address space (see @userbuf)
23 * @csize: number of bytes to copy
24 * @offset: offset in bytes into the page (based on pfn) to begin the copy
25 * @userbuf: if set, @buf is in user address space, use copy_to_user(),
26 * otherwise @buf is in kernel address space, use memcpy().
28 * Copy a page from "oldmem". For this page, there is no pte mapped
29 * in the current kernel.
31 * Calling copy_to_user() in atomic context is not desirable. Hence first
32 * copying the data to a pre-allocated kernel page and then copying to user
33 * space in non-atomic context.
35 ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
36 size_t csize, unsigned long offset, int userbuf)
43 vaddr = kmap_atomic_pfn(pfn);
46 memcpy(buf, (vaddr + offset), csize);
49 if (!kdump_buf_page) {
50 pr_warning("Kdump: Kdump buffer page not allocated\n");
54 copy_page(kdump_buf_page, vaddr);
56 if (copy_to_user(buf, (kdump_buf_page + offset), csize))
63 static int __init kdump_buf_page_init(void)
67 kdump_buf_page = kmalloc(PAGE_SIZE, GFP_KERNEL);
68 if (!kdump_buf_page) {
69 pr_warning("Kdump: Failed to allocate kdump buffer page\n");
75 arch_initcall(kdump_buf_page_init);