linux/include/linux/kmsg_dump.h
Jocelyn Falempe e1a261ba59 printk: Add a short description string to kmsg_dump()
kmsg_dump doesn't forward the panic reason string to the kmsg_dumper
callback.
This patch adds a new struct kmsg_dump_detail, that will hold the
reason and description, and pass it to the dump() callback.

To avoid updating all kmsg_dump() call, it adds a kmsg_dump_desc()
function and a macro for backward compatibility.

I've written this for drm_panic, but it can be useful for other
kmsg_dumper.
It allows to see the panic reason, like "sysrq triggered crash"
or "VFS: Unable to mount root fs on xxxx" on the drm panic screen.

v2:
 * Use a struct kmsg_dump_detail to hold the reason and description
   pointer, for more flexibility if we want to add other parameters.
   (Kees Cook)
 * Fix powerpc/nvram_64 build, as I didn't update the forward
   declaration of oops_to_nvram()

Signed-off-by: Jocelyn Falempe <jfalempe@redhat.com>
Acked-by: Petr Mladek <pmladek@suse.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Acked-by: Kees Cook <kees@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240702122639.248110-1-jfalempe@redhat.com
2024-07-17 12:35:24 +02:00

127 lines
3.1 KiB
C

/*
* linux/include/kmsg_dump.h
*
* Copyright (C) 2009 Net Insight AB
*
* Author: Simon Kagstrom <simon.kagstrom@netinsight.net>
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file COPYING in the main directory of this archive
* for more details.
*/
#ifndef _LINUX_KMSG_DUMP_H
#define _LINUX_KMSG_DUMP_H
#include <linux/errno.h>
#include <linux/list.h>
/*
* Keep this list arranged in rough order of priority. Anything listed after
* KMSG_DUMP_OOPS will not be logged by default unless printk.always_kmsg_dump
* is passed to the kernel.
*/
enum kmsg_dump_reason {
KMSG_DUMP_UNDEF,
KMSG_DUMP_PANIC,
KMSG_DUMP_OOPS,
KMSG_DUMP_EMERG,
KMSG_DUMP_SHUTDOWN,
KMSG_DUMP_MAX
};
/**
* struct kmsg_dump_iter - iterator for retrieving kernel messages
* @cur_seq: Points to the oldest message to dump
* @next_seq: Points after the newest message to dump
*/
struct kmsg_dump_iter {
u64 cur_seq;
u64 next_seq;
};
/**
* struct kmsg_dump_detail - kernel crash detail
* @reason: reason for the crash, see kmsg_dump_reason.
* @description: optional short string, to provide additional information.
*/
struct kmsg_dump_detail {
enum kmsg_dump_reason reason;
const char *description;
};
/**
* struct kmsg_dumper - kernel crash message dumper structure
* @list: Entry in the dumper list (private)
* @dump: Call into dumping code which will retrieve the data with
* through the record iterator
* @max_reason: filter for highest reason number that should be dumped
* @registered: Flag that specifies if this is already registered
*/
struct kmsg_dumper {
struct list_head list;
void (*dump)(struct kmsg_dumper *dumper, struct kmsg_dump_detail *detail);
enum kmsg_dump_reason max_reason;
bool registered;
};
#ifdef CONFIG_PRINTK
void kmsg_dump_desc(enum kmsg_dump_reason reason, const char *desc);
bool kmsg_dump_get_line(struct kmsg_dump_iter *iter, bool syslog,
char *line, size_t size, size_t *len);
bool kmsg_dump_get_buffer(struct kmsg_dump_iter *iter, bool syslog,
char *buf, size_t size, size_t *len_out);
void kmsg_dump_rewind(struct kmsg_dump_iter *iter);
int kmsg_dump_register(struct kmsg_dumper *dumper);
int kmsg_dump_unregister(struct kmsg_dumper *dumper);
const char *kmsg_dump_reason_str(enum kmsg_dump_reason reason);
#else
static inline void kmsg_dump_desc(enum kmsg_dump_reason reason, const char *desc)
{
}
static inline bool kmsg_dump_get_line(struct kmsg_dump_iter *iter, bool syslog,
const char *line, size_t size, size_t *len)
{
return false;
}
static inline bool kmsg_dump_get_buffer(struct kmsg_dump_iter *iter, bool syslog,
char *buf, size_t size, size_t *len)
{
return false;
}
static inline void kmsg_dump_rewind(struct kmsg_dump_iter *iter)
{
}
static inline int kmsg_dump_register(struct kmsg_dumper *dumper)
{
return -EINVAL;
}
static inline int kmsg_dump_unregister(struct kmsg_dumper *dumper)
{
return -EINVAL;
}
static inline const char *kmsg_dump_reason_str(enum kmsg_dump_reason reason)
{
return "Disabled";
}
#endif
static inline void kmsg_dump(enum kmsg_dump_reason reason)
{
kmsg_dump_desc(reason, NULL);
}
#endif /* _LINUX_KMSG_DUMP_H */