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68 lines
1.7 KiB
68 lines
1.7 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Memory preserving reboot related code. |
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* |
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* Created by: Hariprasad Nellitheertha ([email protected]) |
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* Copyright (C) IBM Corporation, 2004. All rights reserved |
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*/ |
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#include <linux/slab.h> |
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#include <linux/errno.h> |
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#include <linux/highmem.h> |
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#include <linux/crash_dump.h> |
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#include <linux/uaccess.h> |
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static inline bool is_crashed_pfn_valid(unsigned long pfn) |
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{ |
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#ifndef CONFIG_X86_PAE |
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/* |
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* non-PAE kdump kernel executed from a PAE one will crop high pte |
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* bits and poke unwanted space counting again from address 0, we |
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* don't want that. pte must fit into unsigned long. In fact the |
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* test checks high 12 bits for being zero (pfn will be shifted left |
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* by PAGE_SHIFT). |
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*/ |
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return pte_pfn(pfn_pte(pfn, __pgprot(0))) == pfn; |
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#else |
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return true; |
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#endif |
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} |
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/** |
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* copy_oldmem_page - copy one page from "oldmem" |
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* @pfn: page frame number to be copied |
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* @buf: target memory address for the copy; this can be in kernel address |
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* space or user address space (see @userbuf) |
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* @csize: number of bytes to copy |
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* @offset: offset in bytes into the page (based on pfn) to begin the copy |
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* @userbuf: if set, @buf is in user address space, use copy_to_user(), |
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* otherwise @buf is in kernel address space, use memcpy(). |
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* |
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* Copy a page from "oldmem". For this page, there might be no pte mapped |
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* in the current kernel. |
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*/ |
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ssize_t copy_oldmem_page(unsigned long pfn, char *buf, size_t csize, |
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unsigned long offset, int userbuf) |
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{ |
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void *vaddr; |
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if (!csize) |
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return 0; |
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if (!is_crashed_pfn_valid(pfn)) |
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return -EFAULT; |
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vaddr = kmap_local_pfn(pfn); |
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if (!userbuf) { |
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memcpy(buf, vaddr + offset, csize); |
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} else { |
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if (copy_to_user(buf, vaddr + offset, csize)) |
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csize = -EFAULT; |
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} |
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kunmap_local(vaddr); |
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return csize; |
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}
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