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Commit 1ba28e02 authored by Lai Jiangshan's avatar Lai Jiangshan Committed by Ingo Molnar
Browse files

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: default avatarLai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: default avatarSteven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1236356510-8381-4-git-send-email-fweisbec@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 1427cdf0

include/asm-generic/vmlinux.lds.h

+9 −0
Original line number Diff line number Diff line
@@ -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) {		\

include/linux/ftrace.h

+21 −0
Original line number Diff line number Diff line
@@ -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 */

include/linux/module.h

+5 −0
Original line number Diff line number Diff line
@@ -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;

kernel/module.c

+6 −0
Original line number Diff line number Diff line
@@ -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)

kernel/trace/trace.c

+15 −0
Original line number Diff line number Diff line
@@ -3848,6 +3848,21 @@ int trace_vbprintk(unsigned long ip, const char *fmt, va_list args) 
}

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)

{