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Date: Thu, 3 Sep 2009 16:26:00 -0400
From: Jason Baron <jbaron@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: mathieu.desnoyers@...ymtl.ca, roland@...hat.com, rth@...hat.com,
mingo@...e.hu
Subject: [PATCH 3/4] RFC: implement tracepoints on top of jump patching
Convert tracepoints to use the new jump patching infrastructure. See
how easy it is!
Also, notice there is a patch to comment out the workqueue tracepoints. Without
this patch I had some panic when doing the code patching. I think this is
probably due to an iteraction b/w stop_machine() using workqueues to do the
actual patching and the workqueue code itself.
Signed-off-by: Jason Baron <jbaron@...hat.com>
---
arch/x86/kernel/test_nx.c | 3 +++
include/linux/tracepoint.h | 38 ++++++++++++++++++++++----------------
kernel/trace/trace_workqueue.c | 2 ++
kernel/tracepoint.c | 9 +++++++++
4 files changed, 36 insertions(+), 16 deletions(-)
diff --git a/arch/x86/kernel/test_nx.c b/arch/x86/kernel/test_nx.c
index 787a5e4..3dab463 100644
--- a/arch/x86/kernel/test_nx.c
+++ b/arch/x86/kernel/test_nx.c
@@ -15,6 +15,9 @@
#include <asm/uaccess.h>
#include <asm/asm.h>
+#include <linux/jump_label.h>
+
+JUMP_LABEL_NAME(kmalloc);
extern int rodata_test_data;
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 63a3f7a..fdd2d8b 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -16,6 +16,7 @@
#include <linux/types.h>
#include <linux/rcupdate.h>
+#include <linux/jump_label.h>
struct module;
struct tracepoint;
@@ -63,21 +64,25 @@ struct tracepoint {
* not add unwanted padding between the beginning of the section and the
* structure. Force alignment to the same alignment as the section start.
*/
-#define DECLARE_TRACE(name, proto, args) \
- extern struct tracepoint __tracepoint_##name; \
- static inline void trace_##name(proto) \
- { \
- if (unlikely(__tracepoint_##name.state)) \
- __DO_TRACE(&__tracepoint_##name, \
- TP_PROTO(proto), TP_ARGS(args)); \
- } \
- static inline int register_trace_##name(void (*probe)(proto)) \
- { \
- return tracepoint_probe_register(#name, (void *)probe); \
- } \
- static inline int unregister_trace_##name(void (*probe)(proto)) \
- { \
- return tracepoint_probe_unregister(#name, (void *)probe);\
+#define DECLARE_TRACE(name, proto, args) \
+ extern struct tracepoint __tracepoint_##name; \
+ extern const char __sjstrtab_##name[]; \
+ static inline void trace_##name(proto) \
+ { \
+ JUMP_LABEL_IF(name, trace_label, __tracepoint_##name.state); \
+ if (0) { \
+trace_label: \
+ __DO_TRACE(&__tracepoint_##name, \
+ TP_PROTO(proto), TP_ARGS(args)); \
+ } \
+ } \
+ static inline int register_trace_##name(void (*probe)(proto)) \
+ { \
+ return tracepoint_probe_register(#name, (void *)probe); \
+ } \
+ static inline int unregister_trace_##name(void (*probe)(proto)) \
+ { \
+ return tracepoint_probe_unregister(#name, (void *)probe); \
}
@@ -86,7 +91,8 @@ struct tracepoint {
__attribute__((section("__tracepoints_strings"))) = #name; \
struct tracepoint __tracepoint_##name \
__attribute__((section("__tracepoints"), aligned(32))) = \
- { __tpstrtab_##name, 0, reg, unreg, NULL }
+ { __tpstrtab_##name, 0, reg, unreg, NULL }; \
+ JUMP_LABEL_NAME(name);
#define DEFINE_TRACE(name) \
DEFINE_TRACE_FN(name, NULL, NULL);
diff --git a/kernel/trace/trace_workqueue.c b/kernel/trace/trace_workqueue.c
index 40cafb0..bc38428 100644
--- a/kernel/trace/trace_workqueue.c
+++ b/kernel/trace/trace_workqueue.c
@@ -258,6 +258,7 @@ int __init trace_workqueue_early_init(void)
{
int ret, cpu;
+ /*
ret = register_trace_workqueue_insertion(probe_workqueue_insertion);
if (ret)
goto out;
@@ -273,6 +274,7 @@ int __init trace_workqueue_early_init(void)
ret = register_trace_workqueue_destruction(probe_workqueue_destruction);
if (ret)
goto no_creation;
+ */
for_each_possible_cpu(cpu) {
spin_lock_init(&workqueue_cpu_stat(cpu)->lock);
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 9489a0a..1b4acc0 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -25,6 +25,7 @@
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/sched.h>
+#include <linux/jump_label.h>
extern struct tracepoint __start___tracepoints[];
extern struct tracepoint __stop___tracepoints[];
@@ -256,6 +257,11 @@ static void set_tracepoint(struct tracepoint_entry **entry,
* is used.
*/
rcu_assign_pointer(elem->funcs, (*entry)->funcs);
+ if (!elem->state && active) {
+ printk("set_tracepoint: call run_make_jump: %s\n", elem->name);
+ run_make_jump(elem->name);
+ } else if (elem->state && !active)
+ run_make_nop(elem->name);
elem->state = active;
}
@@ -270,6 +276,9 @@ static void disable_tracepoint(struct tracepoint *elem)
if (elem->unregfunc && elem->state)
elem->unregfunc();
+ if (elem->state)
+ run_make_nop(elem->name);
+
elem->state = 0;
rcu_assign_pointer(elem->funcs, NULL);
}
--
1.6.2.5
--
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