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linux-next/include/linux/pstore_ram.h
Anton Vorontsov cbe7cbf5a6 pstore/ram: Make tracing log versioned
Decoding the binary trace w/ a different kernel might be troublesome
since we convert addresses to symbols. For kernels with minimal changes,
the mappings would probably match, but it's not guaranteed at all.
(But still we could convert the addresses by hand, since we do print
raw addresses.)

If we use modules, the symbols could be loaded at different addresses
from the previously booted kernel, and so this would also fail, but
there's nothing we can do about it.

Also, the binary data format that pstore/ram is using in its ringbuffer
may change between the kernels, so here we too must ensure that we're
running the same kernel.

So, there are two questions really:

1. How to compute the unique kernel tag;
2. Where to store it.

In this patch we're using LINUX_VERSION_CODE, just as hibernation
(suspend-to-disk) does. This way we are protecting from the kernel
version mismatch, making sure that we're running the same kernel
version and patch level. We could use CRC of a symbol table (as
suggested by Tony Luck), but for now let's not be that strict.

And as for storing, we are using a small trick here. Instead of
allocating a dedicated buffer for the tag (i.e. another prz), or
hacking ram_core routines to "reserve" some control data in the
buffer, we are just encoding the tag into the buffer signature
(and XOR'ing it with the actual signature value, so that buffers
not needing a tag can just pass zero, which will result into the
plain old PRZ signature).

Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Suggested-by: Tony Luck <tony.luck@intel.com>
Suggested-by: Colin Cross <ccross@android.com>
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-07-17 16:48:09 -07:00

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C

/*
* Copyright (C) 2010 Marco Stornelli <marco.stornelli@gmail.com>
* Copyright (C) 2011 Kees Cook <keescook@chromium.org>
* Copyright (C) 2011 Google, Inc.
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
* may be copied, distributed, and modified under those terms.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
*/
#ifndef __LINUX_PSTORE_RAM_H__
#define __LINUX_PSTORE_RAM_H__
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/types.h>
#include <linux/init.h>
struct persistent_ram_buffer;
struct rs_control;
struct persistent_ram_zone {
phys_addr_t paddr;
size_t size;
void *vaddr;
struct persistent_ram_buffer *buffer;
size_t buffer_size;
/* ECC correction */
char *par_buffer;
char *par_header;
struct rs_control *rs_decoder;
int corrected_bytes;
int bad_blocks;
int ecc_block_size;
int ecc_size;
char *old_log;
size_t old_log_size;
};
struct persistent_ram_zone * __devinit persistent_ram_new(phys_addr_t start,
size_t size, u32 sig,
int ecc_size);
void persistent_ram_free(struct persistent_ram_zone *prz);
void persistent_ram_zap(struct persistent_ram_zone *prz);
int persistent_ram_write(struct persistent_ram_zone *prz, const void *s,
unsigned int count);
void persistent_ram_save_old(struct persistent_ram_zone *prz);
size_t persistent_ram_old_size(struct persistent_ram_zone *prz);
void *persistent_ram_old(struct persistent_ram_zone *prz);
void persistent_ram_free_old(struct persistent_ram_zone *prz);
ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
char *str, size_t len);
/*
* Ramoops platform data
* @mem_size memory size for ramoops
* @mem_address physical memory address to contain ramoops
*/
struct ramoops_platform_data {
unsigned long mem_size;
unsigned long mem_address;
unsigned long record_size;
unsigned long console_size;
unsigned long ftrace_size;
int dump_oops;
int ecc_size;
};
#endif