1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Routines for doing kexec-based kdump
4  *
5  * Copyright (C) 2017 Linaro Limited
6  * Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
7  */
8 
9 #include <linux/crash_dump.h>
10 #include <linux/errno.h>
11 #include <linux/io.h>
12 #include <linux/uio.h>
13 #include <asm/memory.h>
14 
copy_oldmem_page(struct iov_iter * iter,unsigned long pfn,size_t csize,unsigned long offset)15 ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
16 			 size_t csize, unsigned long offset)
17 {
18 	void *vaddr;
19 
20 	if (!csize)
21 		return 0;
22 
23 	vaddr = memremap(__pfn_to_phys(pfn), PAGE_SIZE, MEMREMAP_WB);
24 	if (!vaddr)
25 		return -ENOMEM;
26 
27 	csize = copy_to_iter(vaddr + offset, csize, iter);
28 
29 	memunmap(vaddr);
30 
31 	return csize;
32 }
33 
34 /**
35  * elfcorehdr_read - read from ELF core header
36  * @buf: buffer where the data is placed
37  * @count: number of bytes to read
38  * @ppos: address in the memory
39  *
40  * This function reads @count bytes from elf core header which exists
41  * on crash dump kernel's memory.
42  */
elfcorehdr_read(char * buf,size_t count,u64 * ppos)43 ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos)
44 {
45 	memcpy(buf, phys_to_virt((phys_addr_t)*ppos), count);
46 	*ppos += count;
47 
48 	return count;
49 }
50