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-rw-r--r--MAINTAINERS5
-rw-r--r--arch/arm/kernel/entry-v7m.S2
-rw-r--r--arch/arm/lib/backtrace-clang.S2
-rw-r--r--arch/arm/lib/backtrace.S2
-rw-r--r--arch/arm/mach-rpc/io-acorn.S2
-rw-r--r--arch/arm/vfp/vfphw.S6
-rw-r--r--arch/ia64/include/uapi/asm/cmpxchg.h4
-rw-r--r--arch/openrisc/kernel/entry.S6
-rw-r--r--arch/powerpc/kernel/head_fsl_booke.S2
-rw-r--r--arch/um/include/shared/user.h3
-rw-r--r--arch/x86/kernel/head_32.S2
-rw-r--r--include/asm-generic/vmlinux.lds.h13
-rw-r--r--include/linux/module.h5
-rw-r--r--include/linux/printk.h95
-rw-r--r--init/Kconfig14
-rw-r--r--kernel/module.c5
-rw-r--r--kernel/printk/Makefile1
-rw-r--r--kernel/printk/index.c195
-rw-r--r--kernel/printk/printk.c13
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;

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