diff options
38 files changed, 687 insertions, 657 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 82c932105d31..84dc5790741b 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -4198,6 +4198,15 @@ Format: <bool> (1/Y/y=enable, 0/N/n=disable) default: disabled + printk.console_no_auto_verbose= + Disable console loglevel raise on oops, panic + or lockdep-detected issues (only if lock debug is on). + With an exception to setups with low baudrate on + serial console, keeping this 0 is a good choice + in order to provide more debug information. + Format: <bool> + default: 0 (auto_verbose is enabled) + printk.devkmsg={on,off,ratelimit} Control writing to /dev/kmsg. on - unlimited logging to /dev/kmsg from userspace diff --git a/Documentation/core-api/printk-basics.rst b/Documentation/core-api/printk-basics.rst index 965e4281eddd..2dde24ca7d9f 100644 --- a/Documentation/core-api/printk-basics.rst +++ b/Documentation/core-api/printk-basics.rst @@ -107,9 +107,6 @@ also ``CONFIG_DYNAMIC_DEBUG`` in the case of pr_debug()) is defined. Function reference ================== -.. kernel-doc:: kernel/printk/printk.c - :functions: printk - .. kernel-doc:: include/linux/printk.h - :functions: pr_emerg pr_alert pr_crit pr_err pr_warn pr_notice pr_info + :functions: printk pr_emerg pr_alert pr_crit pr_err pr_warn pr_notice pr_info pr_fmt pr_debug pr_devel pr_cont diff --git a/MAINTAINERS b/MAINTAINERS index 63bddf7b6bf2..0d4b8963f17b 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -15021,6 +15021,11 @@ S: Maintained F: include/linux/printk.h F: kernel/printk/ +PRINTK INDEXING +R: Chris Down <chris@chrisdown.name> +S: Maintained +F: kernel/printk/index.c + PROC FILESYSTEM L: linux-kernel@vger.kernel.org L: linux-fsdevel@vger.kernel.org diff --git a/arch/arm/kernel/entry-v7m.S b/arch/arm/kernel/entry-v7m.S index d0e898608d30..7bde93c10962 100644 --- a/arch/arm/kernel/entry-v7m.S +++ b/arch/arm/kernel/entry-v7m.S @@ -23,7 +23,7 @@ __invalid_entry: adr r0, strerr mrs r1, ipsr mov r2, lr - bl printk + bl _printk #endif mov r0, sp bl show_regs diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index c7bb168b0d97..842427ff2b3c 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -667,9 +667,9 @@ static void do_handle_IPI(int ipinr) break; case IPI_CPU_BACKTRACE: - printk_nmi_enter(); + printk_deferred_enter(); nmi_cpu_backtrace(get_irq_regs()); - printk_nmi_exit(); + printk_deferred_exit(); break; default: diff --git a/arch/arm/lib/backtrace-clang.S b/arch/arm/lib/backtrace-clang.S index 6174c45f53a5..5b2cdb1003e3 100644 --- a/arch/arm/lib/backtrace-clang.S +++ b/arch/arm/lib/backtrace-clang.S @@ -202,7 +202,7 @@ finished_setup: 1006: adr r0, .Lbad mov r1, loglvl mov r2, frame - bl printk + bl _printk no_frame: ldmfd sp!, {r4 - r9, fp, pc} ENDPROC(c_backtrace) .pushsection __ex_table,"a" diff --git a/arch/arm/lib/backtrace.S b/arch/arm/lib/backtrace.S index 872f658638d9..e8408f22d4dc 100644 --- a/arch/arm/lib/backtrace.S +++ b/arch/arm/lib/backtrace.S @@ -103,7 +103,7 @@ for_each_frame: tst frame, mask @ Check for address exceptions 1006: adr r0, .Lbad mov r1, loglvl mov r2, frame - bl printk + bl _printk no_frame: ldmfd sp!, {r4 - r9, pc} ENDPROC(c_backtrace) diff --git a/arch/arm/mach-rpc/io-acorn.S b/arch/arm/mach-rpc/io-acorn.S index b9082a2a2a01..aa9bf0d771c0 100644 --- a/arch/arm/mach-rpc/io-acorn.S +++ b/arch/arm/mach-rpc/io-acorn.S @@ -25,4 +25,4 @@ ENTRY(insl) ENTRY(outsl) adr r0, .Liosl_warning mov r1, lr - b printk + b _printk diff --git a/arch/arm/vfp/vfphw.S b/arch/arm/vfp/vfphw.S index d5837bf05a9a..6f7926c9c179 100644 --- a/arch/arm/vfp/vfphw.S +++ b/arch/arm/vfp/vfphw.S @@ -23,7 +23,7 @@ #ifdef DEBUG stmfd sp!, {r0-r3, ip, lr} ldr r0, =1f - bl printk + bl _printk ldmfd sp!, {r0-r3, ip, lr} .pushsection .rodata, "a" @@ -38,7 +38,7 @@ stmfd sp!, {r0-r3, ip, lr} mov r1, \arg ldr r0, =1f - bl printk + bl _printk ldmfd sp!, {r0-r3, ip, lr} .pushsection .rodata, "a" @@ -55,7 +55,7 @@ mov r2, \arg2 mov r1, \arg1 ldr r0, =1f - bl printk + bl _printk ldmfd sp!, {r0-r3, ip, lr} .pushsection .rodata, "a" diff --git a/arch/ia64/include/uapi/asm/cmpxchg.h b/arch/ia64/include/uapi/asm/cmpxchg.h index 926c6cb1e029..2c2f3cfeaa77 100644 --- a/arch/ia64/include/uapi/asm/cmpxchg.h +++ b/arch/ia64/include/uapi/asm/cmpxchg.h @@ -143,9 +143,9 @@ extern long ia64_cmpxchg_called_with_bad_pointer(void); do { \ if (_cmpxchg_bugcheck_count-- <= 0) { \ void *ip; \ - extern int printk(const char *fmt, ...); \ + extern int _printk(const char *fmt, ...); \ ip = (void *) ia64_getreg(_IA64_REG_IP); \ - printk("CMPXCHG_BUGCHECK: stuck at %p on word %p\n", ip, (v));\ + _printk("CMPXCHG_BUGCHECK: stuck at %p on word %p\n", ip, (v));\ break; \ } \ } while (0) diff --git a/arch/mips/include/asm/asm.h b/arch/mips/include/asm/asm.h index ea4b62ece336..2f8ce94ebaaf 100644 --- a/arch/mips/include/asm/asm.h +++ b/arch/mips/include/asm/asm.h @@ -114,7 +114,7 @@ symbol = value .set push; \ .set reorder; \ PTR_LA a0, 8f; \ - jal printk; \ + jal _printk; \ .set pop; \ TEXT(string) #else diff --git a/arch/openrisc/kernel/entry.S b/arch/openrisc/kernel/entry.S index bc657e55c15f..947613f61d4a 100644 --- a/arch/openrisc/kernel/entry.S +++ b/arch/openrisc/kernel/entry.S @@ -551,7 +551,7 @@ EXCEPTION_ENTRY(_external_irq_handler) l.movhi r3,hi(42f) l.ori r3,r3,lo(42f) l.sw 0x0(r1),r3 - l.jal printk + l.jal _printk l.sw 0x4(r1),r4 l.addi r1,r1,0x8 @@ -681,8 +681,8 @@ _syscall_debug: l.sw -4(r1),r27 l.sw -8(r1),r11 l.addi r1,r1,-8 - l.movhi r27,hi(printk) - l.ori r27,r27,lo(printk) + l.movhi r27,hi(_printk) + l.ori r27,r27,lo(_printk) l.jalr r27 l.nop l.addi r1,r1,8 diff --git a/arch/powerpc/kernel/head_fsl_booke.S b/arch/powerpc/kernel/head_fsl_booke.S index 0f9642f36b49..9a2f4265e6d2 100644 --- a/arch/powerpc/kernel/head_fsl_booke.S +++ b/arch/powerpc/kernel/head_fsl_booke.S @@ -858,7 +858,7 @@ KernelSPE: ori r3,r3,87f@l mr r4,r2 /* current */ lwz r5,_NIP(r1) - bl printk + bl _printk #endif b interrupt_return #ifdef CONFIG_PRINTK diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c index d56254f05e17..cd5f633c9b1b 100644 --- a/arch/powerpc/kernel/traps.c +++ b/arch/powerpc/kernel/traps.c @@ -171,7 +171,6 @@ extern void panic_flush_kmsg_start(void) extern void panic_flush_kmsg_end(void) { - printk_safe_flush_on_panic(); kmsg_dump(KMSG_DUMP_PANIC); bust_spinlocks(0); debug_locks_off(); diff --git a/arch/powerpc/kernel/watchdog.c b/arch/powerpc/kernel/watchdog.c index a165635fd214..f9ea0e5357f9 100644 --- a/arch/powerpc/kernel/watchdog.c +++ b/arch/powerpc/kernel/watchdog.c @@ -184,11 +184,6 @@ static void watchdog_smp_panic(int cpu, u64 tb) wd_smp_unlock(&flags); - printk_safe_flush(); - /* - * printk_safe_flush() seems to require another print - * before anything actually goes out to console. - */ if (sysctl_hardlockup_all_cpu_backtrace) trigger_allbutself_cpu_backtrace(); diff --git a/arch/powerpc/kexec/crash.c b/arch/powerpc/kexec/crash.c index 10f997e6bb95..22ceeeb705ab 100644 --- a/arch/powerpc/kexec/crash.c +++ b/arch/powerpc/kexec/crash.c @@ -313,7 +313,7 @@ void default_machine_crash_shutdown(struct pt_regs *regs) int (*old_handler)(struct pt_regs *regs); /* Avoid hardlocking with irresponsive CPU holding logbuf_lock */ - printk_nmi_enter(); + printk_deferred_enter(); /* * This function is only called after the system diff --git a/arch/um/include/shared/user.h b/arch/um/include/shared/user.h index e793e4212f0a..dd4badffdeb3 100644 --- a/arch/um/include/shared/user.h +++ b/arch/um/include/shared/user.h @@ -38,7 +38,8 @@ extern void panic(const char *fmt, ...) #define UM_KERN_CONT KERN_CONT #ifdef UML_CONFIG_PRINTK -extern int printk(const char *fmt, ...) +#define printk(...) _printk(__VA_ARGS__) +extern int _printk(const char *fmt, ...) __attribute__ ((format (printf, 1, 2))); #else static inline int printk(const char *fmt, ...) diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S index 67f590425d90..d8c64dab0efe 100644 --- a/arch/x86/kernel/head_32.S +++ b/arch/x86/kernel/head_32.S @@ -432,7 +432,7 @@ SYM_FUNC_START(early_ignore_irq) pushl 32(%esp) pushl 40(%esp) pushl $int_msg - call printk + call _printk call dump_stack diff --git a/drivers/base/core.c b/drivers/base/core.c index 3a72241b87c6..280425409b40 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -4579,8 +4579,8 @@ static void __dev_printk(const char *level, const struct device *dev, printk("%s(NULL device *): %pV", level, vaf); } -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, ...) { struct va_format vaf; va_list args; @@ -4594,7 +4594,7 @@ void dev_printk(const char *level, const struct device *dev, va_end(args); } -EXPORT_SYMBOL(dev_printk); +EXPORT_SYMBOL(_dev_printk); #define define_dev_printk_level(func, kern_level) \ void func(const struct device *dev, const char *fmt, ...) \ 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 diff --git a/init/Kconfig b/init/Kconfig index 55f9f7738ebb..e708180e9a59 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -775,6 +775,20 @@ config PRINTK_SAFE_LOG_BUF_SHIFT 13 => 8 KB for each CPU 12 => 4 KB for each CPU +config PRINTK_INDEX + bool "Printk indexing debugfs interface" + depends on PRINTK && DEBUG_FS + help + Add support for indexing of all printk formats known at compile time + at <debugfs>/printk/index/<module>. + + This can be used as part of maintaining daemons which monitor + /dev/kmsg, as it permits auditing the printk formats present in a + kernel, allowing detection of cases where monitored printks are + changed or no longer present. + + There is no additional runtime cost to printk with this enabled. + # # Architectures with an unreliable sched_clock() should select this: # @@ -1509,11 +1523,6 @@ config PRINTK very difficult to diagnose system problems, saying N here is strongly discouraged. -config PRINTK_NMI - def_bool y - depends on PRINTK - depends on HAVE_NMI - config BUG bool "BUG() support" if EXPERT default y diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c index 4b34a9aa32bc..5a5d192a89ac 100644 --- a/kernel/kexec_core.c +++ b/kernel/kexec_core.c @@ -979,7 +979,6 @@ void crash_kexec(struct pt_regs *regs) old_cpu = atomic_cmpxchg(& |