| 1 | /* |
| 2 | * Memory preserving reboot related code. |
| 3 | * |
| 4 | * Created by: Hariprasad Nellitheertha (hari@in.ibm.com) |
| 5 | * Copyright (C) IBM Corporation, 2004. All rights reserved |
| 6 | */ |
| 7 | |
| 8 | #include <linux/errno.h> |
| 9 | #include <linux/highmem.h> |
| 10 | #include <linux/crash_dump.h> |
| 11 | |
| 12 | #include <asm/uaccess.h> |
| 13 | |
| 14 | static void *kdump_buf_page; |
| 15 | |
| 16 | /* Stores the physical address of elf header of crash image. */ |
| 17 | unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX; |
| 18 | |
| 19 | /** |
| 20 | * copy_oldmem_page - copy one page from "oldmem" |
| 21 | * @pfn: page frame number to be copied |
| 22 | * @buf: target memory address for the copy; this can be in kernel address |
| 23 | * space or user address space (see @userbuf) |
| 24 | * @csize: number of bytes to copy |
| 25 | * @offset: offset in bytes into the page (based on pfn) to begin the copy |
| 26 | * @userbuf: if set, @buf is in user address space, use copy_to_user(), |
| 27 | * otherwise @buf is in kernel address space, use memcpy(). |
| 28 | * |
| 29 | * Copy a page from "oldmem". For this page, there is no pte mapped |
| 30 | * in the current kernel. We stitch up a pte, similar to kmap_atomic. |
| 31 | * |
| 32 | * Calling copy_to_user() in atomic context is not desirable. Hence first |
| 33 | * copying the data to a pre-allocated kernel page and then copying to user |
| 34 | * space in non-atomic context. |
| 35 | */ |
| 36 | ssize_t copy_oldmem_page(unsigned long pfn, char *buf, |
| 37 | size_t csize, unsigned long offset, int userbuf) |
| 38 | { |
| 39 | void *vaddr; |
| 40 | |
| 41 | if (!csize) |
| 42 | return 0; |
| 43 | |
| 44 | vaddr = kmap_atomic_pfn(pfn, KM_PTE0); |
| 45 | |
| 46 | if (!userbuf) { |
| 47 | memcpy(buf, (vaddr + offset), csize); |
| 48 | kunmap_atomic(vaddr, KM_PTE0); |
| 49 | } else { |
| 50 | if (!kdump_buf_page) { |
| 51 | printk(KERN_WARNING "Kdump: Kdump buffer page not" |
| 52 | " allocated\n"); |
| 53 | kunmap_atomic(vaddr, KM_PTE0); |
| 54 | return -EFAULT; |
| 55 | } |
| 56 | copy_page(kdump_buf_page, vaddr); |
| 57 | kunmap_atomic(vaddr, KM_PTE0); |
| 58 | if (copy_to_user(buf, (kdump_buf_page + offset), csize)) |
| 59 | return -EFAULT; |
| 60 | } |
| 61 | |
| 62 | return csize; |
| 63 | } |
| 64 | |
| 65 | static int __init kdump_buf_page_init(void) |
| 66 | { |
| 67 | int ret = 0; |
| 68 | |
| 69 | kdump_buf_page = kmalloc(PAGE_SIZE, GFP_KERNEL); |
| 70 | if (!kdump_buf_page) { |
| 71 | printk(KERN_WARNING "Kdump: Failed to allocate kdump buffer" |
| 72 | " page\n"); |
| 73 | ret = -ENOMEM; |
| 74 | } |
| 75 | |
| 76 | return ret; |
| 77 | } |
| 78 | arch_initcall(kdump_buf_page_init); |