From 1ba28e02a18cbdbea123836f6c98efb09cbf59ec Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 6 Mar 2009 17:21:48 +0100 Subject: [PATCH] tracing: add trace_bprintk() Impact: add a generic printk() for tracing, like trace_printk() trace_bprintk() uses the infrastructure to record events on ring_buffer. [ fweisbec@gmail.com: ported to latest -tip, made it work if !CONFIG_MODULES, never free the format strings from modules because we can't keep track of them and conditionnaly create the ftrace format strings section (reported by Steven Rostedt) ] Signed-off-by: Lai Jiangshan Signed-off-by: Frederic Weisbecker Acked-by: Steven Rostedt LKML-Reference: <1236356510-8381-4-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar --- include/asm-generic/vmlinux.lds.h | 9 ++++ include/linux/ftrace.h | 21 ++++++++ include/linux/module.h | 5 ++ kernel/module.c | 6 +++ kernel/trace/trace.c | 15 ++++++ kernel/trace/trace_bprintk.c | 87 +++++++++++++++++++++++++++---- 6 files changed, 133 insertions(+), 10 deletions(-) diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 0add6b28c366..48ade3168b13 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -69,6 +69,14 @@ #define FTRACE_EVENTS() #endif +#ifdef CONFIG_TRACING +#define TRACE_PRINTKS() VMLINUX_SYMBOL(__start___trace_bprintk_fmt) = .; \ + *(__trace_printk_fmt) /* Trace_printk fmt' pointer */ \ + VMLINUX_SYMBOL(__stop___trace_bprintk_fmt) = .; +#else +#define TRACE_PRINTKS() +#endif + /* .data section */ #define DATA_DATA \ *(.data) \ @@ -100,6 +108,7 @@ *(__vermagic) /* Kernel version magic */ \ *(__markers_strings) /* Markers: strings */ \ *(__tracepoints_strings)/* Tracepoints: strings */ \ + TRACE_PRINTKS() \ } \ \ .rodata1 : AT(ADDR(.rodata1) - LOAD_OFFSET) { \ diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 1c9cdca02580..1cc8ca453a9b 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -225,6 +225,27 @@ extern int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr); #ifdef CONFIG_TRACE_BPRINTK extern int trace_vbprintk(unsigned long ip, const char *fmt, va_list args); +extern int __trace_bprintk(unsigned long ip, const char *fmt, ...) + __attribute__ ((format (printf, 2, 3))); + +static inline void ____trace_bprintk_check_format(const char *fmt, ...) + __attribute__ ((format (printf, 1, 2))); +static inline void ____trace_bprintk_check_format(const char *fmt, ...) {} +#define __trace_bprintk_check_format(fmt, args...) \ +do { \ + if (0) \ + ____trace_bprintk_check_format(fmt, ##args); \ +} while (0) + +#define trace_bprintk(fmt, args...) \ +do { \ + static char *__attribute__((section("__trace_bprintk_fmt"))) \ + trace_bprintk_fmt = fmt; \ + __trace_bprintk_check_format(fmt, ##args); \ + __trace_bprintk(_THIS_IP_, trace_bprintk_fmt, ##args); \ +} while (0) +#else +#define trace_bprintk trace_printk #endif /* May be defined in arch */ diff --git a/include/linux/module.h b/include/linux/module.h index 145a75528cc1..8cbec972d8e7 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -329,6 +329,11 @@ struct module unsigned int num_tracepoints; #endif +#ifdef CONFIG_TRACE_BPRINTK + const char **trace_bprintk_fmt_start; + unsigned int num_trace_bprintk_fmt; +#endif + #ifdef CONFIG_MODULE_UNLOAD /* What modules depend on me? */ struct list_head modules_which_use_me; diff --git a/kernel/module.c b/kernel/module.c index 22d7379709da..2dece104f9a1 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2158,6 +2158,12 @@ static noinline struct module *load_module(void __user *umod, &mod->num_tracepoints); #endif +#ifdef CONFIG_TRACE_BPRINTK + mod->trace_bprintk_fmt_start = section_objs(hdr, sechdrs, secstrings, + "__trace_bprintk_fmt", sizeof(char *), + &mod->num_trace_bprintk_fmt); +#endif + #ifdef CONFIG_MODVERSIONS if ((mod->num_syms && !mod->crcs) || (mod->num_gpl_syms && !mod->gpl_crcs) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index ff53509e19f8..46b3cd7a5752 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3848,6 +3848,21 @@ out: } EXPORT_SYMBOL_GPL(trace_vbprintk); +int __trace_bprintk(unsigned long ip, const char *fmt, ...) +{ + int ret; + va_list ap; + + if (!fmt) + return 0; + + va_start(ap, fmt); + ret = trace_vbprintk(ip, fmt, ap); + va_end(ap); + return ret; +} +EXPORT_SYMBOL_GPL(__trace_bprintk); + static int trace_panic_handler(struct notifier_block *this, unsigned long event, void *unused) { diff --git a/kernel/trace/trace_bprintk.c b/kernel/trace/trace_bprintk.c index 1f8e532c3fb9..f4c245a5cd33 100644 --- a/kernel/trace/trace_bprintk.c +++ b/kernel/trace/trace_bprintk.c @@ -19,9 +19,21 @@ #include "trace.h" +#ifdef CONFIG_MODULES + /* binary printk basic */ static DEFINE_MUTEX(btrace_mutex); -static int btrace_metadata_count; +/* + * modules trace_bprintk()'s formats are autosaved in struct trace_bprintk_fmt + * which are queued on trace_bprintk_fmt_list. + */ +static LIST_HEAD(trace_bprintk_fmt_list); + +struct trace_bprintk_fmt { + struct list_head list; + char fmt[0]; +}; + static inline void lock_btrace(void) { @@ -33,26 +45,75 @@ static inline void unlock_btrace(void) mutex_unlock(&btrace_mutex); } -static void get_btrace_metadata(void) + +static inline struct trace_bprintk_fmt *lookup_format(const char *fmt) { - lock_btrace(); - btrace_metadata_count++; - unlock_btrace(); + struct trace_bprintk_fmt *pos; + list_for_each_entry(pos, &trace_bprintk_fmt_list, list) { + if (!strcmp(pos->fmt, fmt)) + return pos; + } + return NULL; } -static void put_btrace_metadata(void) +static +void hold_module_trace_bprintk_format(const char **start, const char **end) { + const char **iter; lock_btrace(); - btrace_metadata_count--; + for (iter = start; iter < end; iter++) { + struct trace_bprintk_fmt *tb_fmt = lookup_format(*iter); + if (tb_fmt) { + *iter = tb_fmt->fmt; + continue; + } + + tb_fmt = kmalloc(offsetof(struct trace_bprintk_fmt, fmt) + + strlen(*iter) + 1, GFP_KERNEL); + if (tb_fmt) { + list_add_tail(&tb_fmt->list, &trace_bprintk_fmt_list); + strcpy(tb_fmt->fmt, *iter); + *iter = tb_fmt->fmt; + } else + *iter = NULL; + } unlock_btrace(); } +static int module_trace_bprintk_format_notify(struct notifier_block *self, + unsigned long val, void *data) +{ + struct module *mod = data; + if (mod->num_trace_bprintk_fmt) { + const char **start = mod->trace_bprintk_fmt_start; + const char **end = start + mod->num_trace_bprintk_fmt; + + if (val == MODULE_STATE_COMING) + hold_module_trace_bprintk_format(start, end); + } + return 0; +} + +#else /* !CONFIG_MODULES */ +__init static int +module_trace_bprintk_format_notify(struct notifier_block *self, + unsigned long val, void *data) +{ + return 0; +} +#endif /* CONFIG_MODULES */ + + +__initdata_or_module static +struct notifier_block module_trace_bprintk_format_nb = { + .notifier_call = module_trace_bprintk_format_notify, +}; + /* events tracer */ int trace_bprintk_enable; static void start_bprintk_trace(struct trace_array *tr) { - get_btrace_metadata(); tracing_reset_online_cpus(tr); trace_bprintk_enable = 1; } @@ -61,7 +122,6 @@ static void stop_bprintk_trace(struct trace_array *tr) { trace_bprintk_enable = 0; tracing_reset_online_cpus(tr); - put_btrace_metadata(); } static int init_bprintk_trace(struct trace_array *tr) @@ -81,7 +141,14 @@ static struct tracer bprintk_trace __read_mostly = static __init int init_bprintk(void) { - return register_tracer(&bprintk_trace); + int ret = register_module_notifier(&module_trace_bprintk_format_nb); + if (ret) + return ret; + + ret = register_tracer(&bprintk_trace); + if (ret) + unregister_module_notifier(&module_trace_bprintk_format_nb); + return ret; } device_initcall(init_bprintk); -- 2.20.1