tracepoints: add DECLARE_TRACE() and DEFINE_TRACE()
Impact: API *CHANGE*. Must update all tracepoint users.
Add DEFINE_TRACE() to tracepoints to let them declare the tracepoint
structure in a single spot for all the kernel. It helps reducing memory
consumption, especially when declaring a lot of tracepoints, e.g. for
kmalloc tracing.
*API CHANGE WARNING*: now, DECLARE_TRACE() must be used in headers for
tracepoint declarations rather than DEFINE_TRACE(). This is the sane way
to do it. The name previously used was misleading.
Updates scheduler instrumentation to follow this API change.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 7e9b42a..7570054 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -24,8 +24,12 @@
const char *name; /* Tracepoint name */
int state; /* State. */
void **funcs;
-} __attribute__((aligned(8)));
-
+} __attribute__((aligned(32))); /*
+ * Aligned on 32 bytes because it is
+ * globally visible and gcc happily
+ * align these on the structure size.
+ * Keep in sync with vmlinux.lds.h.
+ */
#define TPPROTO(args...) args
#define TPARGS(args...) args
@@ -55,15 +59,10 @@
* not add unwanted padding between the beginning of the section and the
* structure. Force alignment to the same alignment as the section start.
*/
-#define DEFINE_TRACE(name, proto, args) \
+#define DECLARE_TRACE(name, proto, args) \
+ extern struct tracepoint __tracepoint_##name; \
static inline void trace_##name(proto) \
{ \
- static const char __tpstrtab_##name[] \
- __attribute__((section("__tracepoints_strings"))) \
- = #name; \
- static struct tracepoint __tracepoint_##name \
- __attribute__((section("__tracepoints"), aligned(8))) = \
- { __tpstrtab_##name, 0, NULL }; \
if (unlikely(__tracepoint_##name.state)) \
__DO_TRACE(&__tracepoint_##name, \
TPPROTO(proto), TPARGS(args)); \
@@ -77,11 +76,23 @@
return tracepoint_probe_unregister(#name, (void *)probe);\
}
+#define DEFINE_TRACE(name) \
+ static const char __tpstrtab_##name[] \
+ __attribute__((section("__tracepoints_strings"))) = #name; \
+ struct tracepoint __tracepoint_##name \
+ __attribute__((section("__tracepoints"), aligned(32))) = \
+ { __tpstrtab_##name, 0, NULL }
+
+#define EXPORT_TRACEPOINT_SYMBOL_GPL(name) \
+ EXPORT_SYMBOL_GPL(__tracepoint_##name)
+#define EXPORT_TRACEPOINT_SYMBOL(name) \
+ EXPORT_SYMBOL(__tracepoint_##name)
+
extern void tracepoint_update_probe_range(struct tracepoint *begin,
struct tracepoint *end);
#else /* !CONFIG_TRACEPOINTS */
-#define DEFINE_TRACE(name, proto, args) \
+#define DECLARE_TRACE(name, proto, args) \
static inline void _do_trace_##name(struct tracepoint *tp, proto) \
{ } \
static inline void trace_##name(proto) \
@@ -95,6 +106,10 @@
return -ENOSYS; \
}
+#define DEFINE_TRACE(name)
+#define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
+#define EXPORT_TRACEPOINT_SYMBOL(name)
+
static inline void tracepoint_update_probe_range(struct tracepoint *begin,
struct tracepoint *end)
{ }