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// SPDX-License-Identifier: GPL-2.0-only
/*
* Routines for doing kexec-based kdump
*
* Copyright (C) 2017 Linaro Limited
* Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
*/
#include <linux/crash_dump.h>
#include <linux/errno.h>
#include <linux/io.h>
#include <linux/memblock.h>
#include <linux/uaccess.h>
#include <asm/memory.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;
}
/**
* elfcorehdr_read - read from ELF core header
* @buf: buffer where the data is placed
* @count: number of bytes to read
* @ppos: address in the memory
*
* This function reads @count bytes from elf core header which exists
* on crash dump kernel's memory.
*/
ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos)
{
memcpy(buf, phys_to_virt((phys_addr_t)*ppos), count);
return count;
}
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