mirror of
https://github.com/torvalds/linux.git
synced 2024-11-19 10:31:48 +00:00
e62aaeac42
Arch-specific functions are added to allow for implementing a crash dump file interface, /proc/vmcore, which can be viewed as a ELF file. A user space tool, like kexec-tools, is responsible for allocating a separate region for the core's ELF header within crash kdump kernel memory and filling it in when executing kexec_load(). Then, its location will be advertised to crash dump kernel via a new device-tree property, "linux,elfcorehdr", and crash dump kernel preserves the region for later use with reserve_elfcorehdr() at boot time. On crash dump kernel, /proc/vmcore will access the primary kernel's memory with copy_oldmem_page(), which feeds the data page-by-page by ioremap'ing it since it does not reside in linear mapping on crash dump kernel. Meanwhile, elfcorehdr_read() is simple as the region is always mapped. Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> Reviewed-by: James Morse <james.morse@arm.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
72 lines
1.8 KiB
C
72 lines
1.8 KiB
C
/*
|
|
* Routines for doing kexec-based kdump
|
|
*
|
|
* Copyright (C) 2017 Linaro Limited
|
|
* Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License version 2 as
|
|
* published by the Free Software Foundation.
|
|
*/
|
|
|
|
#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
|
|
* @csize: 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;
|
|
}
|