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authorAbhishek Sagar <sagar.abhishek@gmail.com>2008-06-21 23:47:53 +0530
committerIngo Molnar <mingo@elte.hu>2008-06-23 22:10:58 +0200
commitecea656d1d5e912d2f3d332657ea4a6d8380f891 (patch)
treefd139cdd762230bf4e55a1341ba29e2b309968b1
parent785656a41f9a9c0e843a23d1ae05d900b5158f8f (diff)
ftrace: freeze kprobe'd records
Let records identified as being kprobe'd be marked as "frozen". The trouble with records which have a kprobe installed on their mcount call-site is that they don't get updated. So if such a function which is currently being traced gets its tracing disabled due to a new filter rule (or because it was added to the notrace list) then it won't be updated and continue being traced. This patch allows scanning of all frozen records during tracing to check if they should be traced. Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--include/linux/ftrace.h6
-rw-r--r--kernel/trace/ftrace.c72
-rw-r--r--kernel/trace/trace.c3
3 files changed, 79 insertions, 2 deletions
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 366098d591d..3121b95443d 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -49,6 +49,7 @@ enum {
FTRACE_FL_ENABLED = (1 << 3),
FTRACE_FL_NOTRACE = (1 << 4),
FTRACE_FL_CONVERTED = (1 << 5),
+ FTRACE_FL_FROZEN = (1 << 6),
};
struct dyn_ftrace {
@@ -73,15 +74,18 @@ extern void ftrace_caller(void);
extern void ftrace_call(void);
extern void mcount_call(void);
+extern int skip_trace(unsigned long ip);
+
void ftrace_disable_daemon(void);
void ftrace_enable_daemon(void);
#else
+# define skip_trace(ip) ({ 0; })
# define ftrace_force_update() ({ 0; })
# define ftrace_set_filter(buf, len, reset) do { } while (0)
# define ftrace_disable_daemon() do { } while (0)
# define ftrace_enable_daemon() do { } while (0)
-#endif
+#endif /* CONFIG_DYNAMIC_FTRACE */
/* totally disable ftrace - can not re-enable after this */
void ftrace_kill(void);
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index f1e9e5c74e6..d1238163155 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -163,6 +163,8 @@ enum {
};
static int ftrace_filtered;
+static int tracing_on;
+static int frozen_record_count;
static struct hlist_head ftrace_hash[FTRACE_HASHSIZE];
@@ -195,6 +197,71 @@ static int ftrace_record_suspend;
static struct dyn_ftrace *ftrace_free_records;
+
+#ifdef CONFIG_KPROBES
+static inline void freeze_record(struct dyn_ftrace *rec)
+{
+ if (!(rec->flags & FTRACE_FL_FROZEN)) {
+ rec->flags |= FTRACE_FL_FROZEN;
+ frozen_record_count++;
+ }
+}
+
+static inline void unfreeze_record(struct dyn_ftrace *rec)
+{
+ if (rec->flags & FTRACE_FL_FROZEN) {
+ rec->flags &= ~FTRACE_FL_FROZEN;
+ frozen_record_count--;
+ }
+}
+
+static inline int record_frozen(struct dyn_ftrace *rec)
+{
+ return rec->flags & FTRACE_FL_FROZEN;
+}
+#else
+# define freeze_record(rec) ({ 0; })
+# define unfreeze_record(rec) ({ 0; })
+# define record_frozen(rec) ({ 0; })
+#endif /* CONFIG_KPROBES */
+
+int skip_trace(unsigned long ip)
+{
+ unsigned long fl;
+ struct dyn_ftrace *rec;
+ struct hlist_node *t;
+ struct hlist_head *head;
+
+ if (frozen_record_count == 0)
+ return 0;
+
+ head = &ftrace_hash[hash_long(ip, FTRACE_HASHBITS)];
+ hlist_for_each_entry_rcu(rec, t, head, node) {
+ if (rec->ip == ip) {
+ if (record_frozen(rec)) {
+ if (rec->flags & FTRACE_FL_FAILED)
+ return 1;
+
+ if (!(rec->flags & FTRACE_FL_CONVERTED))
+ return 1;
+
+ if (!tracing_on || !ftrace_enabled)
+ return 1;
+
+ if (ftrace_filtered) {
+ fl = rec->flags & (FTRACE_FL_FILTER |
+ FTRACE_FL_NOTRACE);
+ if (!fl || (fl & FTRACE_FL_NOTRACE))
+ return 1;
+ }
+ }
+ break;
+ }
+ }
+
+ return 0;
+}
+
static inline int
ftrace_ip_in_hash(unsigned long ip, unsigned long key)
{
@@ -489,8 +556,11 @@ static int __ftrace_modify_code(void *data)
*/
__ftrace_update_code(NULL);
ftrace_replace_code(1);
- } else if (*command & FTRACE_DISABLE_CALLS)
+ tracing_on = 1;
+ } else if (*command & FTRACE_DISABLE_CALLS) {
ftrace_replace_code(0);
+ tracing_on = 0;
+ }
if (*command & FTRACE_UPDATE_TRACE_FUNC)
ftrace_update_ftrace_func(ftrace_trace_function);
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 6e9dae7eb41..9ade79369bf 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -988,6 +988,9 @@ function_trace_call(unsigned long ip, unsigned long parent_ip)
if (unlikely(!tracer_enabled))
return;
+ if (skip_trace(ip))
+ return;
+
local_irq_save(flags);
cpu = raw_smp_processor_id();
data = tr->data[cpu];