xref: /linux-6.15/include/linux/kmsg_dump.h (revision e1a261ba)

/*
 * linux/include/kmsg_dump.h
 *
 * Copyright (C) 2009 Net Insight AB
 *
 * Author: Simon Kagstrom <[email protected]>
 *
 * 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 */