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 <laijs@cn.fujitsu.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1236356510-8381-4-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 0add6b2..48ade31 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 1c9cdca..1cc8ca4 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -225,6 +225,27 @@
#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 145a755..8cbec97 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -329,6 +329,11 @@
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;