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kernel_optimize_test/include/linux/printk.h
Sergey Senozhatsky ab6f762f0f printk: queue wake_up_klogd irq_work only if per-CPU areas are ready 
printk_deferred(), similarly to printk_safe/printk_nmi, does not
immediately attempt to print a new message on the consoles, avoiding
calls into non-reentrant kernel paths, e.g. scheduler or timekeeping,
which potentially can deadlock the system.

Those printk() flavors, instead, rely on per-CPU flush irq_work to print
messages from safer contexts.  For same reasons (recursive scheduler or
timekeeping calls) printk() uses per-CPU irq_work in order to wake up
user space syslog/kmsg readers.

However, only printk_safe/printk_nmi do make sure that per-CPU areas
have been initialised and that it's safe to modify per-CPU irq_work.
This means that, for instance, should printk_deferred() be invoked "too
early", that is before per-CPU areas are initialised, printk_deferred()
will perform illegal per-CPU access.

Lech Perczak [0] reports that after commit 1b710b1b10 ("char/random:
silence a lockdep splat with printk()") user-space syslog/kmsg readers
are not able to read new kernel messages.

The reason is printk_deferred() being called too early (as was pointed
out by Petr and John).

Fix printk_deferred() and do not queue per-CPU irq_work before per-CPU
areas are initialized.

Link: https://lore.kernel.org/lkml/aa0732c6-5c4e-8a8b-a1c1-75ebe3dca05b@camlintechnologies.com/
Reported-by: Lech Perczak <l.perczak@camlintechnologies.com>
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Tested-by: Jann Horn <jannh@google.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-10 13:18:57 -07:00

532 lines
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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __KERNEL_PRINTK__
#define __KERNEL_PRINTK__
#include <stdarg.h>
#include <linux/init.h>
#include <linux/kern_levels.h>
#include <linux/linkage.h>
#include <linux/cache.h>
extern const char linux_banner[];
extern const char linux_proc_banner[];
#define PRINTK_MAX_SINGLE_HEADER_LEN 2
static inline int printk_get_level(const char *buffer)
{
if (buffer[0] == KERN_SOH_ASCII && buffer[1]) {
switch (buffer[1]) {
case '0' ... '7':
case 'c': /* KERN_CONT */
return buffer[1];
}
}
return 0;
}
static inline const char *printk_skip_level(const char *buffer)
{
if (printk_get_level(buffer))
return buffer + 2;
return buffer;
}
static inline const char *printk_skip_headers(const char *buffer)
{
while (printk_get_level(buffer))
buffer = printk_skip_level(buffer);
return buffer;
}
#define CONSOLE_EXT_LOG_MAX 8192
/* printk's without a loglevel use this.. */
#define MESSAGE_LOGLEVEL_DEFAULT CONFIG_MESSAGE_LOGLEVEL_DEFAULT
/* We show everything that is MORE important than this.. */
#define CONSOLE_LOGLEVEL_SILENT 0 /* Mum's the word */
#define CONSOLE_LOGLEVEL_MIN 1 /* Minimum loglevel we let people use */
#define CONSOLE_LOGLEVEL_DEBUG 10 /* issue debug messages */
#define CONSOLE_LOGLEVEL_MOTORMOUTH 15 /* You can't shut this one up */
/*
* Default used to be hard-coded at 7, quiet used to be hardcoded at 4,
* we're now allowing both to be set from kernel config.
*/
#define CONSOLE_LOGLEVEL_DEFAULT CONFIG_CONSOLE_LOGLEVEL_DEFAULT
#define CONSOLE_LOGLEVEL_QUIET CONFIG_CONSOLE_LOGLEVEL_QUIET
extern int console_printk[];
#define console_loglevel (console_printk[0])
#define default_message_loglevel (console_printk[1])
#define minimum_console_loglevel (console_printk[2])
#define default_console_loglevel (console_printk[3])
static inline void console_silent(void)
{
console_loglevel = CONSOLE_LOGLEVEL_SILENT;
}
static inline void console_verbose(void)
{
if (console_loglevel)
console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH;
}
/* strlen("ratelimit") + 1 */
#define DEVKMSG_STR_MAX_SIZE 10
extern char devkmsg_log_str[];
struct ctl_table;
extern int suppress_printk;
struct va_format {
const char *fmt;
va_list *va;
};
/*
* FW_BUG
* Add this to a message where you are sure the firmware is buggy or behaves
* really stupid or out of spec. Be aware that the responsible BIOS developer
* should be able to fix this issue or at least get a concrete idea of the
* problem by reading your message without the need of looking at the kernel
* code.
*
* Use it for definite and high priority BIOS bugs.
*
* FW_WARN
* Use it for not that clear (e.g. could the kernel messed up things already?)
* and medium priority BIOS bugs.
*
* FW_INFO
* Use this one if you want to tell the user or vendor about something
* suspicious, but generally harmless related to the firmware.
*
* Use it for information or very low priority BIOS bugs.
*/
#define FW_BUG "[Firmware Bug]: "
#define FW_WARN "[Firmware Warn]: "
#define FW_INFO "[Firmware Info]: "
/*
* HW_ERR
* Add this to a message for hardware errors, so that user can report
* it to hardware vendor instead of LKML or software vendor.
*/
#define HW_ERR "[Hardware Error]: "
/*
* DEPRECATED
* Add this to a message whenever you want to warn user space about the use
* of a deprecated aspect of an API so they can stop using it
*/
#define DEPRECATED "[Deprecated]: "
/*
* Dummy printk for disabled debugging statements to use whilst maintaining
* gcc's format checking.
*/
#define no_printk(fmt, ...) \
({ \
if (0) \
printk(fmt, ##__VA_ARGS__); \
0; \
})
#ifdef CONFIG_EARLY_PRINTK
extern asmlinkage __printf(1, 2)
void early_printk(const char *fmt, ...);
#else
static inline __printf(1, 2) __cold
void early_printk(const char *s, ...) { }
#endif
#ifdef CONFIG_PRINTK_NMI
extern void printk_nmi_enter(void);
extern void printk_nmi_exit(void);
extern void printk_nmi_direct_enter(void);
extern void printk_nmi_direct_exit(void);
#else
static inline void printk_nmi_enter(void) { }
static inline void printk_nmi_exit(void) { }
static inline void printk_nmi_direct_enter(void) { }
static inline void printk_nmi_direct_exit(void) { }
#endif /* PRINTK_NMI */
#ifdef CONFIG_PRINTK
asmlinkage __printf(5, 0)
int vprintk_emit(int facility, int level,
const char *dict, size_t dictlen,
const char *fmt, va_list args);
asmlinkage __printf(1, 0)
int vprintk(const char *fmt, va_list args);
asmlinkage __printf(1, 2) __cold
int printk(const char *fmt, ...);
/*
* Special printk facility for scheduler/timekeeping use only, _DO_NOT_USE_ !
*/
__printf(1, 2) __cold int printk_deferred(const char *fmt, ...);
/*
* Please don't use printk_ratelimit(), because it shares ratelimiting state
* with all other unrelated printk_ratelimit() callsites. Instead use
* printk_ratelimited() or plain old __ratelimit().
*/
extern int __printk_ratelimit(const char *func);
#define printk_ratelimit() __printk_ratelimit(__func__)
extern bool printk_timed_ratelimit(unsigned long *caller_jiffies,
unsigned int interval_msec);
extern int printk_delay_msec;
extern int dmesg_restrict;
extern int
devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write, void __user *buf,
size_t *lenp, loff_t *ppos);
extern void wake_up_klogd(void);
char *log_buf_addr_get(void);
u32 log_buf_len_get(void);
void log_buf_vmcoreinfo_setup(void);
void __init setup_log_buf(int early);
__printf(1, 2) void dump_stack_set_arch_desc(const char *fmt, ...);
void dump_stack_print_info(const char *log_lvl);
void show_regs_print_info(const char *log_lvl);
extern asmlinkage void dump_stack(void) __cold;
extern void printk_safe_flush(void);
extern void printk_safe_flush_on_panic(void);
#else
static inline __printf(1, 0)
int vprintk(const char *s, va_list args)
{
return 0;
}
static inline __printf(1, 2) __cold
int printk(const char *s, ...)
{
return 0;
}
static inline __printf(1, 2) __cold
int printk_deferred(const char *s, ...)
{
return 0;
}
static inline int printk_ratelimit(void)
{
return 0;
}
static inline bool printk_timed_ratelimit(unsigned long *caller_jiffies,
unsigned int interval_msec)
{
return false;
}
static inline void wake_up_klogd(void)
{
}
static inline char *log_buf_addr_get(void)
{
return NULL;
}
static inline u32 log_buf_len_get(void)
{
return 0;
}
static inline void log_buf_vmcoreinfo_setup(void)
{
}
static inline void setup_log_buf(int early)
{
}
static inline __printf(1, 2) void dump_stack_set_arch_desc(const char *fmt, ...)
{
}
static inline void dump_stack_print_info(const char *log_lvl)
{
}
static inline void show_regs_print_info(const char *log_lvl)
{
}
static inline void dump_stack(void)
{
}
static inline void printk_safe_flush(void)
{
}
static inline void printk_safe_flush_on_panic(void)
{
}
#endif
extern int kptr_restrict;
#ifndef pr_fmt
#define pr_fmt(fmt) fmt
#endif
/*
* These can be used to print at the various log levels.
* All of these will print unconditionally, although note that pr_debug()
* and other debug macros are compiled out unless either DEBUG is defined
* or CONFIG_DYNAMIC_DEBUG is set.
*/
#define pr_emerg(fmt, ...) \
printk(KERN_EMERG pr_fmt(fmt), ##__VA_ARGS__)
#define pr_alert(fmt, ...) \
printk(KERN_ALERT pr_fmt(fmt), ##__VA_ARGS__)
#define pr_crit(fmt, ...) \
printk(KERN_CRIT pr_fmt(fmt), ##__VA_ARGS__)
#define pr_err(fmt, ...) \
printk(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__)
#define pr_warn(fmt, ...) \
printk(KERN_WARNING pr_fmt(fmt), ##__VA_ARGS__)
#define pr_notice(fmt, ...) \
printk(KERN_NOTICE pr_fmt(fmt), ##__VA_ARGS__)
#define pr_info(fmt, ...) \
printk(KERN_INFO pr_fmt(fmt), ##__VA_ARGS__)
/*
* Like KERN_CONT, pr_cont() should only be used when continuing
* a line with no newline ('\n') enclosed. Otherwise it defaults
* back to KERN_DEFAULT.
*/
#define pr_cont(fmt, ...) \
printk(KERN_CONT fmt, ##__VA_ARGS__)
/* pr_devel() should produce zero code unless DEBUG is defined */
#ifdef DEBUG
#define pr_devel(fmt, ...) \
printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
#else
#define pr_devel(fmt, ...) \
no_printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
#endif
/* If you are writing a driver, please use dev_dbg instead */
#if defined(CONFIG_DYNAMIC_DEBUG)
#include <linux/dynamic_debug.h>
/* dynamic_pr_debug() uses pr_fmt() internally so we don't need it here */
#define pr_debug(fmt, ...) \
dynamic_pr_debug(fmt, ##__VA_ARGS__)
#elif defined(DEBUG)
#define pr_debug(fmt, ...) \
printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
#else
#define pr_debug(fmt, ...) \
no_printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
#endif
/*
* Print a one-time message (analogous to WARN_ONCE() et al):
*/
#ifdef CONFIG_PRINTK
#define printk_once(fmt, ...) \
({ \
static bool __section(.data.once) __print_once; \
bool __ret_print_once = !__print_once; \
\
if (!__print_once) { \
__print_once = true; \
printk(fmt, ##__VA_ARGS__); \
} \
unlikely(__ret_print_once); \
})
#define printk_deferred_once(fmt, ...) \
({ \
static bool __section(.data.once) __print_once; \
bool __ret_print_once = !__print_once; \
\
if (!__print_once) { \
__print_once = true; \
printk_deferred(fmt, ##__VA_ARGS__); \
} \
unlikely(__ret_print_once); \
})
#else
#define printk_once(fmt, ...) \
no_printk(fmt, ##__VA_ARGS__)
#define printk_deferred_once(fmt, ...) \
no_printk(fmt, ##__VA_ARGS__)
#endif
#define pr_emerg_once(fmt, ...) \
printk_once(KERN_EMERG pr_fmt(fmt), ##__VA_ARGS__)
#define pr_alert_once(fmt, ...) \
printk_once(KERN_ALERT pr_fmt(fmt), ##__VA_ARGS__)
#define pr_crit_once(fmt, ...) \
printk_once(KERN_CRIT pr_fmt(fmt), ##__VA_ARGS__)
#define pr_err_once(fmt, ...) \
printk_once(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__)
#define pr_warn_once(fmt, ...) \
printk_once(KERN_WARNING pr_fmt(fmt), ##__VA_ARGS__)
#define pr_notice_once(fmt, ...) \
printk_once(KERN_NOTICE pr_fmt(fmt), ##__VA_ARGS__)
#define pr_info_once(fmt, ...) \
printk_once(KERN_INFO pr_fmt(fmt), ##__VA_ARGS__)
#define pr_cont_once(fmt, ...) \
printk_once(KERN_CONT pr_fmt(fmt), ##__VA_ARGS__)
#if defined(DEBUG)
#define pr_devel_once(fmt, ...) \
printk_once(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
#else
#define pr_devel_once(fmt, ...) \
no_printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
#endif
/* If you are writing a driver, please use dev_dbg instead */
#if defined(DEBUG)
#define pr_debug_once(fmt, ...) \
printk_once(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
#else
#define pr_debug_once(fmt, ...) \
no_printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
#endif
/*
* ratelimited messages with local ratelimit_state,
* no local ratelimit_state used in the !PRINTK case
*/
#ifdef CONFIG_PRINTK
#define printk_ratelimited(fmt, ...) \
({ \
static DEFINE_RATELIMIT_STATE(_rs, \
DEFAULT_RATELIMIT_INTERVAL, \
DEFAULT_RATELIMIT_BURST); \
\
if (__ratelimit(&_rs)) \
printk(fmt, ##__VA_ARGS__); \
})
#else
#define printk_ratelimited(fmt, ...) \
no_printk(fmt, ##__VA_ARGS__)
#endif
#define pr_emerg_ratelimited(fmt, ...) \
printk_ratelimited(KERN_EMERG pr_fmt(fmt), ##__VA_ARGS__)
#define pr_alert_ratelimited(fmt, ...) \
printk_ratelimited(KERN_ALERT pr_fmt(fmt), ##__VA_ARGS__)
#define pr_crit_ratelimited(fmt, ...) \
printk_ratelimited(KERN_CRIT pr_fmt(fmt), ##__VA_ARGS__)
#define pr_err_ratelimited(fmt, ...) \
printk_ratelimited(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__)
#define pr_warn_ratelimited(fmt, ...) \
printk_ratelimited(KERN_WARNING pr_fmt(fmt), ##__VA_ARGS__)
#define pr_notice_ratelimited(fmt, ...) \
printk_ratelimited(KERN_NOTICE pr_fmt(fmt), ##__VA_ARGS__)
#define pr_info_ratelimited(fmt, ...) \
printk_ratelimited(KERN_INFO pr_fmt(fmt), ##__VA_ARGS__)
/* no pr_cont_ratelimited, don't do that... */
#if defined(DEBUG)
#define pr_devel_ratelimited(fmt, ...) \
printk_ratelimited(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
#else
#define pr_devel_ratelimited(fmt, ...) \
no_printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
#endif
/* If you are writing a driver, please use dev_dbg instead */
#if defined(CONFIG_DYNAMIC_DEBUG)
/* descriptor check is first to prevent flooding with "callbacks suppressed" */
#define pr_debug_ratelimited(fmt, ...) \
do { \
static DEFINE_RATELIMIT_STATE(_rs, \
DEFAULT_RATELIMIT_INTERVAL, \
DEFAULT_RATELIMIT_BURST); \
DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, pr_fmt(fmt)); \
if (DYNAMIC_DEBUG_BRANCH(descriptor) && \
__ratelimit(&_rs)) \
__dynamic_pr_debug(&descriptor, pr_fmt(fmt), ##__VA_ARGS__); \
} while (0)
#elif defined(DEBUG)
#define pr_debug_ratelimited(fmt, ...) \
printk_ratelimited(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
#else
#define pr_debug_ratelimited(fmt, ...) \
no_printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
#endif
extern const struct file_operations kmsg_fops;
enum {
DUMP_PREFIX_NONE,
DUMP_PREFIX_ADDRESS,
DUMP_PREFIX_OFFSET
};
extern int hex_dump_to_buffer(const void *buf, size_t len, int rowsize,
int groupsize, char *linebuf, size_t linebuflen,
bool ascii);
#ifdef CONFIG_PRINTK
extern void print_hex_dump(const char *level, const char *prefix_str,
int prefix_type, int rowsize, int groupsize,
const void *buf, size_t len, bool ascii);
#else
static inline void print_hex_dump(const char *level, const char *prefix_str,
int prefix_type, int rowsize, int groupsize,
const void *buf, size_t len, bool ascii)
{
}
static inline void print_hex_dump_bytes(const char *prefix_str, int prefix_type,
const void *buf, size_t len)
{
}
#endif
#if defined(CONFIG_DYNAMIC_DEBUG)
#define print_hex_dump_debug(prefix_str, prefix_type, rowsize, \
groupsize, buf, len, ascii) \
dynamic_hex_dump(prefix_str, prefix_type, rowsize, \
groupsize, buf, len, ascii)
#elif defined(DEBUG)
#define print_hex_dump_debug(prefix_str, prefix_type, rowsize, \
groupsize, buf, len, ascii) \
print_hex_dump(KERN_DEBUG, prefix_str, prefix_type, rowsize, \
groupsize, buf, len, ascii)
#else
static inline void print_hex_dump_debug(const char *prefix_str, int prefix_type,
int rowsize, int groupsize,
const void *buf, size_t len, bool ascii)
{
}
#endif
/**
* print_hex_dump_bytes - shorthand form of print_hex_dump() with default params
* @prefix_str: string to prefix each line with;
* caller supplies trailing spaces for alignment if desired
* @prefix_type: controls whether prefix of an offset, address, or none
* is printed (%DUMP_PREFIX_OFFSET, %DUMP_PREFIX_ADDRESS, %DUMP_PREFIX_NONE)
* @buf: data blob to dump
* @len: number of bytes in the @buf
*
* Calls print_hex_dump(), with log level of KERN_DEBUG,
* rowsize of 16, groupsize of 1, and ASCII output included.
*/
#define print_hex_dump_bytes(prefix_str, prefix_type, buf, len) \
print_hex_dump_debug(prefix_str, prefix_type, 16, 1, buf, len, true)
#endif
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