/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* internal.h - printk internal definitions
*/
#include <linux/console.h>
#include <linux/percpu.h>
#include <linux/types.h>
#if defined(CONFIG_PRINTK) && defined(CONFIG_SYSCTL)
struct ctl_table;
void __init printk_sysctl_init(void);
int devkmsg_sysctl_set_loglvl(const 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__)
/*
* Identify if legacy printing is forced in a dedicated kthread. If
* true, all printing via console lock occurs within a dedicated
* legacy printer thread. The only exception is on panic, after the
* nbcon consoles have had their chance to print the panic messages
* first.
*/
#ifdef CONFIG_PREEMPT_RT
# define force_legacy_kthread() (true)
#else
# define force_legacy_kthread() (false)
#endif
#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 */
};
struct printk_ringbuffer;
struct dev_printk_info;
extern struct printk_ringbuffer *prb;
extern bool printk_kthreads_running;
__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);
void __printk_safe_enter(void);
void __printk_safe_exit(void);
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);
bool is_printk_legacy_deferred(void);
u16 printk_parse_prefix(const char *text, int *level,
enum printk_info_flags *flags);
void console_lock_spinning_enable(void);
int console_lock_spinning_disable_and_check(int cookie);
u64 nbcon_seq_read(struct console *con);
void nbcon_seq_force(struct console *con, u64 seq);
bool nbcon_alloc(struct console *con);
void nbcon_free(struct console *con);
enum nbcon_prio nbcon_get_default_prio(void);
void nbcon_atomic_flush_pending(void);
bool nbcon_legacy_emit_next_record(struct console *con, bool *handover,
int cookie, bool use_atomic);
bool nbcon_kthread_create(struct console *con);
void nbcon_kthread_stop(struct console *con);
void nbcon_kthreads_wake(void);
/*
* Check if the given console is currently capable and allowed to print
* records. Note that this function does not consider the current context,
* which can also play a role in deciding if @con can be used to print
* records.
*/
static inline bool console_is_usable(struct console *con, short flags, bool use_atomic)
{
if (!(flags & CON_ENABLED))
return false;
if ((flags & CON_SUSPENDED))
return false;
if (flags & CON_NBCON) {
/* The write_atomic() callback is optional. */
if (use_atomic && !con->write_atomic)
return false;
/*
* For the !use_atomic case, @printk_kthreads_running is not
* checked because the write_thread() callback is also used
* via the legacy loop when the printer threads are not
* available.
*/
} else {
if (!con->write)
return false;
}
/*
* Console drivers may assume that per-cpu resources have been
* allocated. So unless they're explicitly marked as being able to
* cope (CON_ANYTIME) don't call them until this CPU is officially up.
*/
if (!cpu_online(raw_smp_processor_id()) && !(flags & CON_ANYTIME))
return false;
return true;
}
/**
* nbcon_kthread_wake - Wake up a console printing thread
* @con: Console to operate on
*/
static inline void nbcon_kthread_wake(struct console *con)
{
/*
* Guarantee any new records can be seen by tasks preparing to wait
* before this context checks if the rcuwait is empty.
*
* The full memory barrier in rcuwait_wake_up() pairs with the full
* memory barrier within set_current_state() of
* ___rcuwait_wait_event(), which is called after prepare_to_rcuwait()
* adds the waiter but before it has checked the wait condition.
*
* This pairs with nbcon_kthread_func:A.
*/
rcuwait_wake_up(&con->rcuwait); /* LMM(nbcon_kthread_wake:A) */
}
#else
#define PRINTK_PREFIX_MAX 0
#define PRINTK_MESSAGE_MAX 0
#define PRINTKRB_RECORD_MAX 0
#define printk_kthreads_running (false)
/*
* 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 void defer_console_output(void) { }
static inline bool is_printk_legacy_deferred(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_free(struct console *con) { }
static inline enum nbcon_prio nbcon_get_default_prio(void) { return NBCON_PRIO_NONE; }
static inline void nbcon_atomic_flush_pending(void) { }
static inline bool nbcon_legacy_emit_next_record(struct console *con, bool *handover,
int cookie, bool use_atomic) { return false; }
static inline void nbcon_kthread_wake(struct console *con) { }
static inline void nbcon_kthreads_wake(void) { }
static inline bool console_is_usable(struct console *con, short flags,
bool use_atomic) { return false; }
#endif /* CONFIG_PRINTK */
extern bool have_boot_console;
extern bool have_nbcon_console;
extern bool have_legacy_console;
extern bool legacy_allow_panic_sync;
/**
* struct console_flush_type - Define available console flush methods
* @nbcon_atomic: Flush directly using nbcon_atomic() callback
* @nbcon_offload: Offload flush to printer thread
* @legacy_direct: Call the legacy loop in this context
* @legacy_offload: Offload the legacy loop into IRQ or legacy thread
*
* Note that the legacy loop also flushes the nbcon consoles.
*/
struct console_flush_type {
bool nbcon_atomic;
bool nbcon_offload;
bool legacy_direct;
bool legacy_offload;
};
/*
* Identify which console flushing methods should be used in the context of
* the caller.
*/
static inline void printk_get_console_flush_type(struct console_flush_type *ft)
{
memset(ft, 0, sizeof(*ft));
switch (nbcon_get_default_prio()) {
case NBCON_PRIO_NORMAL:
if (have_nbcon_console && !have_boot_console) {
if (printk_kthreads_running)
ft->nbcon_offload = true;
else
ft->nbcon_atomic = true;
}
/* Legacy consoles are flushed directly when possible. */
if (have_legacy_console || have_boot_console) {
if (!is_printk_legacy_deferred())
ft->legacy_direct = true;
else
ft->legacy_offload = true;
}
break;
case NBCON_PRIO_EMERGENCY:
if (have_nbcon_console && !have_boot_console)
ft->nbcon_atomic = true;
/* Legacy consoles are flushed directly when possible. */
if (have_legacy_console || have_boot_console) {
if (!is_printk_legacy_deferred())
ft->legacy_direct = true;
else
ft->legacy_offload = true;
}
break;
case NBCON_PRIO_PANIC:
/*
* In panic, the nbcon consoles will directly print. But
* only allowed if there are no boot consoles.
*/
if (have_nbcon_console && !have_boot_console)
ft->nbcon_atomic = true;
if (have_legacy_console || have_boot_console) {
/*
* This is the same decision as NBCON_PRIO_NORMAL
* except that offloading never occurs in panic.
*
* Note that console_flush_on_panic() will flush
* legacy consoles anyway, even if unsafe.
*/
if (!is_printk_legacy_deferred())
ft->legacy_direct = true;
/*
* In panic, if nbcon atomic printing occurs,
* the legacy consoles must remain silent until
* explicitly allowed.
*/
if (ft->nbcon_atomic && !legacy_allow_panic_sync)
ft->legacy_direct = false;
}
break;
default:
WARN_ON_ONCE(1);
break;
}
}
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);
void console_prepend_replay(struct printk_message *pmsg);
#endif
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