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author | Linus Torvalds <torvalds@linux-foundation.org> | 2021-09-02 04:41:13 +0300 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-09-02 04:41:13 +0300 |
commit | df43d903828c59afb9e93b59835127a02e1f8144 (patch) | |
tree | 39be64267622b2efe8e2fc39298a4245d76f2337 /include | |
parent | 9e5f3ffcf1cb34e7c7beb3f79a96f58536730924 (diff) | |
parent | c985aafb60e972c0a6b8d0bd65e03af5890b748a (diff) | |
download | linux-df43d903828c59afb9e93b59835127a02e1f8144.tar.xz |
Merge tag 'printk-for-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux
Pull printk updates from Petr Mladek:
- Optionally, provide an index of possible printk messages via
<debugfs>/printk/index/. It can be used when monitoring important
kernel messages on a farm of various hosts. The monitor has to be
updated when some messages has changed or are not longer available by
a newly deployed kernel.
- Add printk.console_no_auto_verbose boot parameter. It allows to
generate crash dump even with slow consoles in a reasonable time
frame.
- Remove printk_safe buffers. The messages are always stored directly
to the main logbuffer, even in NMI or recursive context. Also it
allows to serialize syslog operations by a mutex instead of a spin
lock.
- Misc clean up and build fixes.
* tag 'printk-for-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux:
printk/index: Fix -Wunused-function warning
lib/nmi_backtrace: Serialize even messages about idle CPUs
printk: Add printk.console_no_auto_verbose boot parameter
printk: Remove console_silent()
lib/test_scanf: Handle n_bits == 0 in random tests
printk: syslog: close window between wait and read
printk: convert @syslog_lock to mutex
printk: remove NMI tracking
printk: remove safe buffers
printk: track/limit recursion
lib/nmi_backtrace: explicitly serialize banner and regs
printk: Move the printk() kerneldoc comment to its new home
printk/index: Fix warning about missing prototypes
MIPS/asm/printk: Fix build failure caused by printk
printk: index: Add indexing support to dev_printk
printk: Userspace format indexing support
printk: Rework parse_prefix into printk_parse_prefix
printk: Straighten out log_flags into printk_info_flags
string_helpers: Escape double quotes in escape_special
printk/console: Check consistent sequence number when handling race in console_unlock()
Diffstat (limited to 'include')
-rw-r--r-- | include/asm-generic/vmlinux.lds.h | 13 | ||||
-rw-r--r-- | include/linux/dev_printk.h | 66 | ||||
-rw-r--r-- | include/linux/hardirq.h | 2 | ||||
-rw-r--r-- | include/linux/module.h | 5 | ||||
-rw-r--r-- | include/linux/printk.h | 171 |
5 files changed, 202 insertions, 55 deletions
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 62669b36a772..aa50bf2959fe 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -483,6 +483,8 @@ \ TRACEDATA \ \ + PRINTK_INDEX \ + \ /* Kernel symbol table: Normal symbols */ \ __ksymtab : AT(ADDR(__ksymtab) - LOAD_OFFSET) { \ __start___ksymtab = .; \ @@ -894,6 +896,17 @@ #define TRACEDATA #endif +#ifdef CONFIG_PRINTK_INDEX +#define PRINTK_INDEX \ + .printk_index : AT(ADDR(.printk_index) - LOAD_OFFSET) { \ + __start_printk_index = .; \ + *(.printk_index) \ + __stop_printk_index = .; \ + } +#else +#define PRINTK_INDEX +#endif + #define NOTES \ .notes : AT(ADDR(.notes) - LOAD_OFFSET) { \ __start_notes = .; \ diff --git a/include/linux/dev_printk.h b/include/linux/dev_printk.h index 82d3d46005a1..8904063d4c9f 100644 --- a/include/linux/dev_printk.h +++ b/include/linux/dev_printk.h @@ -38,8 +38,8 @@ __printf(3, 4) __cold int dev_printk_emit(int level, const struct device *dev, const char *fmt, ...); __printf(3, 4) __cold -void dev_printk(const char *level, const struct device *dev, - const char *fmt, ...); +void _dev_printk(const char *level, const struct device *dev, + const char *fmt, ...); __printf(2, 3) __cold void _dev_emerg(const struct device *dev, const char *fmt, ...); __printf(2, 3) __cold @@ -69,7 +69,7 @@ static inline void __dev_printk(const char *level, const struct device *dev, struct va_format *vaf) {} static inline __printf(3, 4) -void dev_printk(const char *level, const struct device *dev, +void _dev_printk(const char *level, const struct device *dev, const char *fmt, ...) {} @@ -98,24 +98,56 @@ void _dev_info(const struct device *dev, const char *fmt, ...) #endif /* + * Need to take variadic arguments even though we don't use them, as dev_fmt() + * may only just have been expanded and may result in multiple arguments. + */ +#define dev_printk_index_emit(level, fmt, ...) \ + printk_index_subsys_emit("%s %s: ", level, fmt) + +#define dev_printk_index_wrap(_p_func, level, dev, fmt, ...) \ + ({ \ + dev_printk_index_emit(level, fmt); \ + _p_func(dev, fmt, ##__VA_ARGS__); \ + }) + +/* + * Some callsites directly call dev_printk rather than going through the + * dev_<level> infrastructure, so we need to emit here as well as inside those + * level-specific macros. Only one index entry will be produced, either way, + * since dev_printk's `fmt` isn't known at compile time if going through the + * dev_<level> macros. + * + * dev_fmt() isn't called for dev_printk when used directly, as it's used by + * the dev_<level> macros internally which already have dev_fmt() processed. + * + * We also can't use dev_printk_index_wrap directly, because we have a separate + * level to process. + */ +#define dev_printk(level, dev, fmt, ...) \ + ({ \ + dev_printk_index_emit(level, fmt); \ + _dev_printk(level, dev, fmt, ##__VA_ARGS__); \ + }) + +/* * #defines for all the dev_<level> macros to prefix with whatever * possible use of #define dev_fmt(fmt) ... */ -#define dev_emerg(dev, fmt, ...) \ - _dev_emerg(dev, dev_fmt(fmt), ##__VA_ARGS__) -#define dev_crit(dev, fmt, ...) \ - _dev_crit(dev, dev_fmt(fmt), ##__VA_ARGS__) -#define dev_alert(dev, fmt, ...) \ - _dev_alert(dev, dev_fmt(fmt), ##__VA_ARGS__) -#define dev_err(dev, fmt, ...) \ - _dev_err(dev, dev_fmt(fmt), ##__VA_ARGS__) -#define dev_warn(dev, fmt, ...) \ - _dev_warn(dev, dev_fmt(fmt), ##__VA_ARGS__) -#define dev_notice(dev, fmt, ...) \ - _dev_notice(dev, dev_fmt(fmt), ##__VA_ARGS__) -#define dev_info(dev, fmt, ...) \ - _dev_info(dev, dev_fmt(fmt), ##__VA_ARGS__) +#define dev_emerg(dev, fmt, ...) \ + dev_printk_index_wrap(_dev_emerg, KERN_EMERG, dev, dev_fmt(fmt), ##__VA_ARGS__) +#define dev_crit(dev, fmt, ...) \ + dev_printk_index_wrap(_dev_crit, KERN_CRIT, dev, dev_fmt(fmt), ##__VA_ARGS__) +#define dev_alert(dev, fmt, ...) \ + dev_printk_index_wrap(_dev_alert, KERN_ALERT, dev, dev_fmt(fmt), ##__VA_ARGS__) +#define dev_err(dev, fmt, ...) \ + dev_printk_index_wrap(_dev_err, KERN_ERR, dev, dev_fmt(fmt), ##__VA_ARGS__) +#define dev_warn(dev, fmt, ...) \ + dev_printk_index_wrap(_dev_warn, KERN_WARNING, dev, dev_fmt(fmt), ##__VA_ARGS__) +#define dev_notice(dev, fmt, ...) \ + dev_printk_index_wrap(_dev_notice, KERN_NOTICE, dev, dev_fmt(fmt), ##__VA_ARGS__) +#define dev_info(dev, fmt, ...) \ + dev_printk_index_wrap(_dev_info, KERN_INFO, dev, dev_fmt(fmt), ##__VA_ARGS__) #if defined(CONFIG_DYNAMIC_DEBUG) || \ (defined(CONFIG_DYNAMIC_DEBUG_CORE) && defined(DYNAMIC_DEBUG_MODULE)) diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h index 69bc86ea382c..76878b357ffa 100644 --- a/include/linux/hardirq.h +++ b/include/linux/hardirq.h @@ -116,7 +116,6 @@ extern void rcu_nmi_exit(void); do { \ lockdep_off(); \ arch_nmi_enter(); \ - printk_nmi_enter(); \ BUG_ON(in_nmi() == NMI_MASK); \ __preempt_count_add(NMI_OFFSET + HARDIRQ_OFFSET); \ } while (0) @@ -135,7 +134,6 @@ extern void rcu_nmi_exit(void); do { \ BUG_ON(!in_nmi()); \ __preempt_count_sub(NMI_OFFSET + HARDIRQ_OFFSET); \ - printk_nmi_exit(); \ arch_nmi_exit(); \ lockdep_on(); \ } while (0) diff --git a/include/linux/module.h b/include/linux/module.h index 8a298d820dbc..c9f1200b2312 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -511,6 +511,11 @@ struct module { struct klp_modinfo *klp_info; #endif +#ifdef CONFIG_PRINTK_INDEX + unsigned int printk_index_size; + struct pi_entry **printk_index_start; +#endif + #ifdef CONFIG_MODULE_UNLOAD /* What modules depend on me? */ struct list_head source_list; diff --git a/include/linux/printk.h b/include/linux/printk.h index e834d78f0478..259af4f97f50 100644 --- a/include/linux/printk.h +++ b/include/linux/printk.h @@ -70,16 +70,7 @@ extern int console_printk[]; #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; -} +extern void console_verbose(void); /* strlen("ratelimit") + 1 */ #define DEVKMSG_STR_MAX_SIZE 10 @@ -150,18 +141,6 @@ 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 */ - struct dev_printk_info; #ifdef CONFIG_PRINTK @@ -174,12 +153,22 @@ asmlinkage __printf(1, 0) int vprintk(const char *fmt, va_list args); asmlinkage __printf(1, 2) __cold -int printk(const char *fmt, ...); +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, ...); +__printf(1, 2) __cold int _printk_deferred(const char *fmt, ...); + +extern void __printk_safe_enter(void); +extern void __printk_safe_exit(void); +/* + * The printk_deferred_enter/exit macros are available only as a hack for + * some code paths that need to defer all printk console printing. Interrupts + * must be disabled for the deferred duration. + */ +#define printk_deferred_enter __printk_safe_enter +#define printk_deferred_exit __printk_safe_exit /* * Please don't use printk_ratelimit(), because it shares ratelimiting state @@ -209,8 +198,6 @@ void dump_stack_print_info(const char *log_lvl); void show_regs_print_info(const char *log_lvl); extern asmlinkage void dump_stack_lvl(const char *log_lvl) __cold; 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) @@ -218,15 +205,24 @@ int vprintk(const char *s, va_list args) return 0; } static inline __printf(1, 2) __cold -int printk(const char *s, ...) +int _printk(const char *s, ...) { return 0; } static inline __printf(1, 2) __cold -int printk_deferred(const char *s, ...) +int _printk_deferred(const char *s, ...) { return 0; } + +static inline void printk_deferred_enter(void) +{ +} + +static inline void printk_deferred_exit(void) +{ +} + static inline int printk_ratelimit(void) { return 0; @@ -278,14 +274,6 @@ static inline void dump_stack_lvl(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 #ifdef CONFIG_SMP @@ -348,6 +336,117 @@ extern int kptr_restrict; #define pr_fmt(fmt) fmt #endif +struct module; + +#ifdef CONFIG_PRINTK_INDEX +struct pi_entry { + const char *fmt; + const char *func; + const char *file; + unsigned int line; + + /* + * While printk and pr_* have the level stored in the string at compile + * time, some subsystems dynamically add it at runtime through the + * format string. For these dynamic cases, we allow the subsystem to + * tell us the level at compile time. + * + * NULL indicates that the level, if any, is stored in fmt. + */ + const char *level; + + /* + * The format string used by various subsystem specific printk() + * wrappers to prefix the message. + * + * Note that the static prefix defined by the pr_fmt() macro is stored + * directly in the message format (@fmt), not here. + */ + const char *subsys_fmt_prefix; +} __packed; + +#define __printk_index_emit(_fmt, _level, _subsys_fmt_prefix) \ + do { \ + if (__builtin_constant_p(_fmt) && __builtin_constant_p(_level)) { \ + /* + * We check __builtin_constant_p multiple times here + * for the same input because GCC will produce an error + * if we try to assign a static variable to fmt if it + * is not a constant, even with the outer if statement. + */ \ + static const struct pi_entry _entry \ + __used = { \ + .fmt = __builtin_constant_p(_fmt) ? (_fmt) : NULL, \ + .func = __func__, \ + .file = __FILE__, \ + .line = __LINE__, \ + .level = __builtin_constant_p(_level) ? (_level) : NULL, \ + .subsys_fmt_prefix = _subsys_fmt_prefix,\ + }; \ + static const struct pi_entry *_entry_ptr \ + __used __section(".printk_index") = &_entry; \ + } \ + } while (0) + +#else /* !CONFIG_PRINTK_INDEX */ +#define __printk_index_emit(...) do {} while (0) +#endif /* CONFIG_PRINTK_INDEX */ + +/* + * Some subsystems have their own custom printk that applies a va_format to a + * generic format, for example, to include a device number or other metadata + * alongside the format supplied by the caller. + * + * In order to store these in the way they would be emitted by the printk + * infrastructure, the subsystem provides us with the start, fixed string, and + * any subsequent text in the format string. + * + * We take a variable argument list as pr_fmt/dev_fmt/etc are sometimes passed + * as multiple arguments (eg: `"%s: ", "blah"`), and we must only take the + * first one. + * + * subsys_fmt_prefix must be known at compile time, or compilation will fail + * (since this is a mistake). If fmt or level is not known at compile time, no + * index entry will be made (since this can legitimately happen). + */ +#define printk_index_subsys_emit(subsys_fmt_prefix, level, fmt, ...) \ + __printk_index_emit(fmt, level, subsys_fmt_prefix) + +#define printk_index_wrap(_p_func, _fmt, ...) \ + ({ \ + __printk_index_emit(_fmt, NULL, NULL); \ + _p_func(_fmt, ##__VA_ARGS__); \ + }) + + +/** + * printk - print a kernel message + * @fmt: format string + * + * This is printk(). It can be called from any context. We want it to work. + * + * If printk indexing is enabled, _printk() is called from printk_index_wrap. + * Otherwise, printk is simply #defined to _printk. + * + * We try to grab the console_lock. If we succeed, it's easy - we log the + * output and call the console drivers. If we fail to get the semaphore, we + * place the output into the log buffer and return. The current holder of + * the console_sem will notice the new output in console_unlock(); and will + * send it to the consoles before releasing the lock. + * + * One effect of this deferred printing is that code which calls printk() and + * then changes console_loglevel may break. This is because console_loglevel + * is inspected when the actual printing occurs. + * + * See also: + * printf(3) + * + * See the vsnprintf() documentation for format string extensions over C99. + */ +#define printk(fmt, ...) printk_index_wrap(_printk, fmt, ##__VA_ARGS__) +#define printk_deferred(fmt, ...) \ + printk_index_wrap(_printk_deferred, fmt, ##__VA_ARGS__) + /** * pr_emerg - Print an emergency-level message * @fmt: format string |