Ralf Baechle | 7aa1c8f | 2012-10-11 18:14:58 +0200 | [diff] [blame] | 1 | #include <linux/highmem.h> |
| 2 | #include <linux/bootmem.h> |
| 3 | #include <linux/crash_dump.h> |
| 4 | #include <asm/uaccess.h> |
| 5 | |
Ralf Baechle | 7aa1c8f | 2012-10-11 18:14:58 +0200 | [diff] [blame] | 6 | static int __init parse_savemaxmem(char *p) |
| 7 | { |
| 8 | if (p) |
| 9 | saved_max_pfn = (memparse(p, &p) >> PAGE_SHIFT) - 1; |
| 10 | |
| 11 | return 1; |
| 12 | } |
| 13 | __setup("savemaxmem=", parse_savemaxmem); |
| 14 | |
| 15 | |
| 16 | static void *kdump_buf_page; |
| 17 | |
| 18 | /** |
| 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(). |
| 27 | * |
| 28 | * Copy a page from "oldmem". For this page, there is no pte mapped |
| 29 | * in the current kernel. |
| 30 | * |
| 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. |
| 34 | */ |
| 35 | ssize_t copy_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 | |
| 43 | vaddr = kmap_atomic_pfn(pfn); |
| 44 | |
| 45 | if (!userbuf) { |
| 46 | memcpy(buf, (vaddr + offset), csize); |
| 47 | kunmap_atomic(vaddr); |
| 48 | } else { |
| 49 | if (!kdump_buf_page) { |
| 50 | pr_warning("Kdump: Kdump buffer page not allocated\n"); |
| 51 | |
| 52 | return -EFAULT; |
| 53 | } |
| 54 | copy_page(kdump_buf_page, vaddr); |
| 55 | kunmap_atomic(vaddr); |
| 56 | if (copy_to_user(buf, (kdump_buf_page + offset), csize)) |
| 57 | return -EFAULT; |
| 58 | } |
| 59 | |
| 60 | return csize; |
| 61 | } |
| 62 | |
| 63 | static int __init kdump_buf_page_init(void) |
| 64 | { |
| 65 | int ret = 0; |
| 66 | |
| 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"); |
| 70 | ret = -ENOMEM; |
| 71 | } |
| 72 | |
| 73 | return ret; |
| 74 | } |
| 75 | arch_initcall(kdump_buf_page_init); |