47 lines
1.2 KiB
C
47 lines
1.2 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* This code comes from arch/arm64/kernel/crash_dump.c
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* Created by: AKASHI Takahiro <takahiro.akashi@linaro.org>
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* Copyright (C) 2017 Linaro Limited
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*/
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#include <linux/crash_dump.h>
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#include <linux/io.h>
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/**
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* copy_oldmem_page() - copy one page from old kernel memory
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* @pfn: page frame number to be copied
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* @buf: buffer where the copied page is placed
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* @csize: number of bytes to copy
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* @offset: offset in bytes into the page
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* @userbuf: if set, @buf is in a user address space
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*
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* This function copies one page from old kernel memory into buffer pointed by
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* @buf. If @buf is in userspace, set @userbuf to %1. Returns number of bytes
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* copied or negative error in case of failure.
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*/
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ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
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size_t csize, unsigned long offset,
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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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vaddr = memremap(__pfn_to_phys(pfn), PAGE_SIZE, MEMREMAP_WB);
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if (!vaddr)
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return -ENOMEM;
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if (userbuf) {
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if (copy_to_user((char __user *)buf, vaddr + offset, csize)) {
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memunmap(vaddr);
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return -EFAULT;
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}
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} else
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memcpy(buf, vaddr + offset, csize);
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memunmap(vaddr);
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return csize;
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}
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