| 1 | // SPDX-License-Identifier: GPL-2.0 |
|---|---|
| 2 | /* |
| 3 | * Memory preserving reboot related code. |
| 4 | * |
| 5 | * Created by: Hariprasad Nellitheertha (hari@in.ibm.com) |
| 6 | * Copyright (C) IBM Corporation, 2004. All rights reserved |
| 7 | */ |
| 8 | |
| 9 | #include <linux/slab.h> |
| 10 | #include <linux/errno.h> |
| 11 | #include <linux/highmem.h> |
| 12 | #include <linux/crash_dump.h> |
| 13 | #include <linux/uio.h> |
| 14 | |
| 15 | static inline bool is_crashed_pfn_valid(unsigned long pfn) |
| 16 | { |
| 17 | #ifndef CONFIG_X86_PAE |
| 18 | /* |
| 19 | * non-PAE kdump kernel executed from a PAE one will crop high pte |
| 20 | * bits and poke unwanted space counting again from address 0, we |
| 21 | * don't want that. pte must fit into unsigned long. In fact the |
| 22 | * test checks high 12 bits for being zero (pfn will be shifted left |
| 23 | * by PAGE_SHIFT). |
| 24 | */ |
| 25 | return pte_pfn(pte: pfn_pte(page_nr: pfn, __pgprot(0))) == pfn; |
| 26 | #else |
| 27 | return true; |
| 28 | #endif |
| 29 | } |
| 30 | |
| 31 | ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, size_t csize, |
| 32 | unsigned long offset) |
| 33 | { |
| 34 | void *vaddr; |
| 35 | |
| 36 | if (!csize) |
| 37 | return 0; |
| 38 | |
| 39 | if (!is_crashed_pfn_valid(pfn)) |
| 40 | return -EFAULT; |
| 41 | |
| 42 | vaddr = kmap_local_pfn(pfn); |
| 43 | csize = copy_to_iter(addr: vaddr + offset, bytes: csize, i: iter); |
| 44 | kunmap_local(vaddr); |
| 45 | |
| 46 | return csize; |
| 47 | } |
| 48 |