linux/kernel/printk/internal.h
Thomas Gleixner 06653d57ff printk: nbcon: Add emit function and callback function for atomic printing
Implement an emit function for nbcon consoles to output printk
messages. It utilizes the lockless printk_get_next_message() and
console_prepend_dropped() functions to retrieve/build the output
message. The emit function includes the required safety points to
check for handover/takeover and calls a new write_atomic callback
of the console driver to output the message. It also includes
proper handling for updating the nbcon console sequence number.

A new nbcon_write_context struct is introduced. This is provided
to the write_atomic callback and includes only the information
necessary for performing atomic writes.

Co-developed-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Thomas Gleixner (Intel) <tglx@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20230916192007.608398-8-john.ogness@linutronix.de
2023-09-18 17:03:45 +02:00

139 lines
4.1 KiB
C

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* internal.h - printk internal definitions
*/
#include <linux/percpu.h>
#include <linux/console.h>
#include "printk_ringbuffer.h"
#if defined(CONFIG_PRINTK) && defined(CONFIG_SYSCTL)
void __init printk_sysctl_init(void);
int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos);
#else
#define printk_sysctl_init() do { } while (0)
#endif
#define con_printk(lvl, con, fmt, ...) \
printk(lvl pr_fmt("%s%sconsole [%s%d] " fmt), \
(con->flags & CON_NBCON) ? "" : "legacy ", \
(con->flags & CON_BOOT) ? "boot" : "", \
con->name, con->index, ##__VA_ARGS__)
#ifdef CONFIG_PRINTK
#ifdef CONFIG_PRINTK_CALLER
#define PRINTK_PREFIX_MAX 48
#else
#define PRINTK_PREFIX_MAX 32
#endif
/*
* the maximum size of a formatted record (i.e. with prefix added
* per line and dropped messages or in extended message format)
*/
#define PRINTK_MESSAGE_MAX 2048
/* the maximum size allowed to be reserved for a record */
#define PRINTKRB_RECORD_MAX 1024
/* Flags for a single printk record. */
enum printk_info_flags {
LOG_NEWLINE = 2, /* text ended with a newline */
LOG_CONT = 8, /* text is a fragment of a continuation line */
};
extern struct printk_ringbuffer *prb;
__printf(4, 0)
int vprintk_store(int facility, int level,
const struct dev_printk_info *dev_info,
const char *fmt, va_list args);
__printf(1, 0) int vprintk_default(const char *fmt, va_list args);
__printf(1, 0) int vprintk_deferred(const char *fmt, va_list args);
bool printk_percpu_data_ready(void);
#define printk_safe_enter_irqsave(flags) \
do { \
local_irq_save(flags); \
__printk_safe_enter(); \
} while (0)
#define printk_safe_exit_irqrestore(flags) \
do { \
__printk_safe_exit(); \
local_irq_restore(flags); \
} while (0)
void defer_console_output(void);
u16 printk_parse_prefix(const char *text, int *level,
enum printk_info_flags *flags);
u64 nbcon_seq_read(struct console *con);
void nbcon_seq_force(struct console *con, u64 seq);
bool nbcon_alloc(struct console *con);
void nbcon_init(struct console *con);
void nbcon_free(struct console *con);
#else
#define PRINTK_PREFIX_MAX 0
#define PRINTK_MESSAGE_MAX 0
#define PRINTKRB_RECORD_MAX 0
/*
* In !PRINTK builds we still export console_sem
* semaphore and some of console functions (console_unlock()/etc.), so
* printk-safe must preserve the existing local IRQ guarantees.
*/
#define printk_safe_enter_irqsave(flags) local_irq_save(flags)
#define printk_safe_exit_irqrestore(flags) local_irq_restore(flags)
static inline bool printk_percpu_data_ready(void) { return false; }
static inline u64 nbcon_seq_read(struct console *con) { return 0; }
static inline void nbcon_seq_force(struct console *con, u64 seq) { }
static inline bool nbcon_alloc(struct console *con) { return false; }
static inline void nbcon_init(struct console *con) { }
static inline void nbcon_free(struct console *con) { }
#endif /* CONFIG_PRINTK */
extern struct printk_buffers printk_shared_pbufs;
/**
* struct printk_buffers - Buffers to read/format/output printk messages.
* @outbuf: After formatting, contains text to output.
* @scratchbuf: Used as temporary ringbuffer reading and string-print space.
*/
struct printk_buffers {
char outbuf[PRINTK_MESSAGE_MAX];
char scratchbuf[PRINTKRB_RECORD_MAX];
};
/**
* struct printk_message - Container for a prepared printk message.
* @pbufs: printk buffers used to prepare the message.
* @outbuf_len: The length of prepared text in @pbufs->outbuf to output. This
* does not count the terminator. A value of 0 means there is
* nothing to output and this record should be skipped.
* @seq: The sequence number of the record used for @pbufs->outbuf.
* @dropped: The number of dropped records from reading @seq.
*/
struct printk_message {
struct printk_buffers *pbufs;
unsigned int outbuf_len;
u64 seq;
unsigned long dropped;
};
bool other_cpu_in_panic(void);
bool printk_get_next_message(struct printk_message *pmsg, u64 seq,
bool is_extended, bool may_supress);
#ifdef CONFIG_PRINTK
void console_prepend_dropped(struct printk_message *pmsg, unsigned long dropped);
#endif