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- // SPDX-License-Identifier: GPL-2.0
- /*
- * This code comes from arch/arm64/kernel/crash_dump.c
- * Created by: AKASHI Takahiro <takahiro.akashi@linaro.org>
- * Copyright (C) 2017 Linaro Limited
- */
- #include <linux/crash_dump.h>
- #include <linux/io.h>
- /**
- * copy_oldmem_page() - copy one page from old kernel memory
- * @pfn: page frame number to be copied
- * @buf: buffer where the copied page is placed
- * @csize: number of bytes to copy
- * @offset: offset in bytes into the page
- * @userbuf: if set, @buf is in a user address space
- *
- * This function copies one page from old kernel memory into buffer pointed by
- * @buf. If @buf is in userspace, set @userbuf to %1. Returns number of bytes
- * copied or negative error in case of failure.
- */
- ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
- size_t csize, unsigned long offset,
- int userbuf)
- {
- void *vaddr;
- if (!csize)
- return 0;
- vaddr = memremap(__pfn_to_phys(pfn), PAGE_SIZE, MEMREMAP_WB);
- if (!vaddr)
- return -ENOMEM;
- if (userbuf) {
- if (copy_to_user((char __user *)buf, vaddr + offset, csize)) {
- memunmap(vaddr);
- return -EFAULT;
- }
- } else
- memcpy(buf, vaddr + offset, csize);
- memunmap(vaddr);
- return csize;
- }
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