diff options
| -rw-r--r-- | MAINTAINERS | 5 | ||||
| -rw-r--r-- | arch/arm/kernel/entry-v7m.S | 2 | ||||
| -rw-r--r-- | arch/arm/lib/backtrace-clang.S | 2 | ||||
| -rw-r--r-- | arch/arm/lib/backtrace.S | 2 | ||||
| -rw-r--r-- | arch/arm/mach-rpc/io-acorn.S | 2 | ||||
| -rw-r--r-- | arch/arm/vfp/vfphw.S | 6 | ||||
| -rw-r--r-- | arch/ia64/include/uapi/asm/cmpxchg.h | 4 | ||||
| -rw-r--r-- | arch/openrisc/kernel/entry.S | 6 | ||||
| -rw-r--r-- | arch/powerpc/kernel/head_fsl_booke.S | 2 | ||||
| -rw-r--r-- | arch/um/include/shared/user.h | 3 | ||||
| -rw-r--r-- | arch/x86/kernel/head_32.S | 2 | ||||
| -rw-r--r-- | include/asm-generic/vmlinux.lds.h | 13 | ||||
| -rw-r--r-- | include/linux/module.h | 5 | ||||
| -rw-r--r-- | include/linux/printk.h | 95 | ||||
| -rw-r--r-- | init/Kconfig | 14 | ||||
| -rw-r--r-- | kernel/module.c | 5 | ||||
| -rw-r--r-- | kernel/printk/Makefile | 1 | ||||
| -rw-r--r-- | kernel/printk/index.c | 195 | ||||
| -rw-r--r-- | kernel/printk/printk.c | 13 |
19 files changed, 353 insertions, 24 deletions
diff --git a/MAINTAINERS b/MAINTAINERS index a61f4f3b78a9..a19a104e0cc4 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -14918,6 +14918,11 @@ 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 + PRISM54 WIRELESS DRIVER M: Luis Chamberlain <mcgrof@kernel.org> L: linux-wireless@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/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/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/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/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 17325416e2de..ddb2ff158321 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 = .; \ @@ -893,6 +895,17 @@ #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/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..2651b82ed352 100644 --- a/include/linux/printk.h +++ b/include/linux/printk.h @@ -174,12 +174,12 @@ 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, ...); /* * Please don't use printk_ratelimit(), because it shares ratelimiting state @@ -218,12 +218,12 @@ 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; } @@ -348,6 +348,93 @@ 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__); \ + }) + + +#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 bb0d6e6262b1..ccffa7ae5ccc 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: # diff --git a/kernel/module.c b/kernel/module.c index ed13917ea5f3..40ec9a030eec 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -3355,6 +3355,11 @@ static int find_module_sections(struct module *mod, struct load_info *info) sizeof(unsigned long), &mod->num_kprobe_blacklist); #endif +#ifdef CONFIG_PRINTK_INDEX + mod->printk_index_start = section_objs(info, ".printk_index", + sizeof(*mod->printk_index_start), + &mod->printk_index_size); +#endif #ifdef CONFIG_HAVE_STATIC_CALL_INLINE mod->static_call_sites = section_objs(info, ".static_call_sites", sizeof(*mod->static_call_sites), diff --git a/kernel/printk/Makefile b/kernel/printk/Makefile index eee3dc9b60a9..d118739874c0 100644 --- a/kernel/printk/Makefile +++ b/kernel/printk/Makefile @@ -3,3 +3,4 @@ obj-y = printk.o obj-$(CONFIG_PRINTK) += printk_safe.o obj-$(CONFIG_A11Y_BRAILLE_CONSOLE) += braille.o obj-$(CONFIG_PRINTK) += printk_ringbuffer.o +obj-$(CONFIG_PRINTK_INDEX) += index.o diff --git a/kernel/printk/index.c b/kernel/printk/index.c new file mode 100644 index 000000000000..ca062f5e1779 --- /dev/null +++ b/kernel/printk/index.c @@ -0,0 +1,195 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Userspace indexing of printk formats + */ + +#include <linux/debugfs.h> +#include <linux/module.h> +#include <linux/printk.h> +#include <linux/slab.h> +#include <linux/string_helpers.h> + +#include "internal.h" + +extern struct pi_entry *__start_printk_index[]; +extern struct pi_entry *__stop_printk_index[]; + +/* The base dir for module formats, typically debugfs/printk/index/ */ +static struct dentry *dfs_index; + +static struct pi_entry *pi_get_entry(const struct module *mod, loff_t pos) +{ + struct pi_entry **entries; + unsigned int nr_entries; + +#ifdef CONFIG_MODULES + if (mod) { + entries = mod->printk_index_start; + nr_entries = mod->printk_index_size; + } +#endif + + if (!mod) { + /* vmlinux, comes from linker symbols */ + entries = __start_printk_index; + nr_entries = __stop_printk_index - __start_printk_index; + } + + if (pos >= nr_entries) + return NULL; + + return entries[pos]; +} + +static void *pi_next(struct seq_file *s, void *v, loff_t *pos) +{ + const struct module *mod = s->file->f_inode->i_private; + struct pi_entry *entry = pi_get_entry(mod, *pos); + + (*pos)++; + + return entry; +} + +static void *pi_start(struct seq_file *s, loff_t *pos) +{ + /* + * Make show() print the header line. Do not update *pos because + * pi_next() still has to return the entry at index 0 later. + */ + if (*pos == 0) + return SEQ_START_TOKEN; + + return pi_next(s, NULL, pos); +} + +/* + * We need both ESCAPE_ANY and explicit characters from ESCAPE_SPECIAL in @only + * because otherwise ESCAPE_NAP will cause double quotes and backslashes to be + * ignored for quoting. + */ +#define seq_escape_printf_format(s, src) \ + seq_escape_str(s, src, ESCAPE_ANY | ESCAPE_NAP | ESCAPE_APPEND, "\"\\") + +static int pi_show(struct seq_file *s, void *v) +{ + const struct pi_entry *entry = v; + int level = LOGLEVEL_DEFAULT; + enum printk_info_flags flags = 0; + u16 prefix_len = 0; + + if (v == SEQ_START_TOKEN) { + seq_puts(s, "# <level/flags> filename:line function \"format\"\n"); + return 0; + } + + if (!entry->fmt) + return 0; + + if (entry->level) + printk_parse_prefix(entry->level, &level, &flags); + else + prefix_len = printk_parse_prefix(entry->fmt, &level, &flags); + + + if (flags & LOG_CONT) { + /* + * LOGLEVEL_DEFAULT here means "use the same level as the + * message we're continuing from", not the default message + * loglevel, so don't display it as such. + */ + if (level == LOGLEVEL_DEFAULT) + seq_puts(s, "<c>"); + else + seq_printf(s, "<%d,c>", level); + } else + seq_printf(s, "<%d>", level); + + seq_printf(s, " %s:%d %s \"", entry->file, entry->line, entry->func); + if (entry->subsys_fmt_prefix) + seq_escape_printf_format(s, entry->subsys_fmt_prefix); + seq_escape_printf_format(s, entry->fmt + prefix_len); + seq_puts(s, "\"\n"); + + return 0; +} + +static void pi_stop(struct seq_file *p, void *v) { } + +static const struct seq_operations dfs_index_sops = { + .start = pi_start, + .next = pi_next, + .show = pi_show, + .stop = pi_stop, +}; + +DEFINE_SEQ_ATTRIBUTE(dfs_index); + +#ifdef CONFIG_MODULES +static const char *pi_get_module_name(struct module *mod) +{ + return mod ? mod->name : "vmlinux"; +} +#else +static const char *pi_get_module_name(struct module *mod) +{ + return "vmlinux"; +} +#endif + +void pi_create_file(struct module *mod) +{ + debugfs_create_file(pi_get_module_name(mod), 0444, dfs_index, + mod, &dfs_index_fops); +} + +void pi_remove_file(struct module *mod) +{ + debugfs_remove(debugfs_lookup(pi_get_module_name(mod), dfs_index)); +} + +#ifdef CONFIG_MODULES +static int pi_module_notify(struct notifier_block *nb, unsigned long op, + void *data) +{ + struct module *mod = data; + + switch (op) { + case MODULE_STATE_COMING: + pi_create_file(mod); + break; + case MODULE_STATE_GOING: + pi_remove_file(mod); + break; + default: /* we don't care about other module states */ + break; + } + + return NOTIFY_OK; +} + +static struct notifier_block module_printk_fmts_nb = { + .notifier_call = pi_module_notify, +}; + +static void __init pi_setup_module_notifier(void) +{ + register_module_notifier(&module_printk_fmts_nb); +} +#else +static inline void __init pi_setup_module_notifier(void) { } +#endif + +static int __init pi_init(void) +{ + struct dentry *dfs_root = debugfs_create_dir("printk", NULL); + + dfs_index = debugfs_create_dir("index", dfs_root); + pi_setup_module_notifier(); + pi_create_file(NULL); + + return 0; +} + +/* debugfs comes up on core and must be initialised first */ +postcore_initcall(pi_init); diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 03956c3eb745..765f7af6ce56 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -2184,10 +2184,13 @@ int vprintk_default(const char *fmt, va_list args) EXPORT_SYMBOL_GPL(vprintk_default); /** - * printk - print a kernel message + * _printk - print a kernel message * @fmt: format string * - * This is printk(). It can be called from any context. We want it to work. + * 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 @@ -2204,7 +2207,7 @@ EXPORT_SYMBOL_GPL(vprintk_default); * * See the vsnprintf() documentation for format string extensions over C99. */ -asmlinkage __visible int printk(const char *fmt, ...) +asmlinkage __visible int _printk(const char *fmt, ...) { va_list args; int r; @@ -2215,7 +2218,7 @@ asmlinkage __visible int printk(const char *fmt, ...) return r; } -EXPORT_SYMBOL(printk); +EXPORT_SYMBOL(_printk); #else /* CONFIG_PRINTK */ @@ -3200,7 +3203,7 @@ int vprintk_deferred(const char *fmt, va_list args) return r; } -int printk_deferred(const char *fmt, ...) +int _printk_deferred(const char *fmt, ...) { va_list args; int r; |