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Subject[PATCH -tip v14 11/12] tracing: Kprobe tracer assigns new event ids for each event
Date
Assigns new event ids for each kprobes event. This doesn't clear ring_buffer
when unregistering each kprobe event. Thus, if you mind 'Unknown event'
messages, clear the buffer manually after changing kprobe events.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Przemysław Pawełczyk <przemyslaw@pawelczyk.it>
Cc: Roland McGrath <roland@redhat.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Vegard Nossum <vegard.nossum@gmail.com>
---
kernel/trace/trace.h | 6 -----
kernel/trace/trace_kprobe.c | 51 +++++++++++++------------------------------
2 files changed, 15 insertions(+), 42 deletions(-)
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 4ce4525..0b78d76 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -43,8 +43,6 @@ enum trace_type {
TRACE_POWER,
TRACE_BLK,
TRACE_KSYM,
- TRACE_KPROBE,
- TRACE_KRETPROBE,

__TRACE_LAST_TYPE,
};
@@ -358,10 +356,6 @@ extern void __ftrace_bad_type(void);
IF_ASSIGN(var, ent, struct kmemtrace_free_entry, \
TRACE_KMEM_FREE); \
IF_ASSIGN(var, ent, struct ksym_trace_entry, TRACE_KSYM);\
- IF_ASSIGN(var, ent, struct kprobe_trace_entry, \
- TRACE_KPROBE); \
- IF_ASSIGN(var, ent, struct kretprobe_trace_entry, \
- TRACE_KRETPROBE); \
__ftrace_bad_type(); \
} while (0)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index ec137ed..0e8498e 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -186,6 +186,7 @@ struct trace_probe {
};
const char *symbol; /* symbol name */
struct ftrace_event_call call;
+ struct trace_event event;
unsigned int nr_args;
struct fetch_func args[];
};
@@ -795,7 +796,7 @@ static __kprobes int kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs)

size = SIZEOF_KPROBE_TRACE_ENTRY(tp->nr_args);

- event = trace_current_buffer_lock_reserve(TRACE_KPROBE, size,
+ event = trace_current_buffer_lock_reserve(call->id, size,
irq_flags, pc);
if (!event)
return 0;
@@ -827,7 +828,7 @@ static __kprobes int kretprobe_trace_func(struct kretprobe_instance *ri,

size = SIZEOF_KRETPROBE_TRACE_ENTRY(tp->nr_args);

- event = trace_current_buffer_lock_reserve(TRACE_KRETPROBE, size,
+ event = trace_current_buffer_lock_reserve(call->id, size,
irq_flags, pc);
if (!event)
return 0;
@@ -853,7 +854,7 @@ print_kprobe_event(struct trace_iterator *iter, int flags)
struct trace_seq *s = &iter->seq;
int i;

- trace_assign_type(field, iter->ent);
+ field = (struct kprobe_trace_entry *)iter->ent;

if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
goto partial;
@@ -880,7 +881,7 @@ print_kretprobe_event(struct trace_iterator *iter, int flags)
struct trace_seq *s = &iter->seq;
int i;

- trace_assign_type(field, iter->ent);
+ field = (struct kretprobe_trace_entry *)iter->ent;

if (!seq_print_ip_sym(s, field->ret_ip, flags | TRACE_ITER_SYM_OFFSET))
goto partial;
@@ -906,16 +907,6 @@ partial:
return TRACE_TYPE_PARTIAL_LINE;
}

-static struct trace_event kprobe_trace_event = {
- .type = TRACE_KPROBE,
- .trace = print_kprobe_event,
-};
-
-static struct trace_event kretprobe_trace_event = {
- .type = TRACE_KRETPROBE,
- .trace = print_kretprobe_event,
-};
-
static int probe_event_enable(struct ftrace_event_call *call)
{
struct trace_probe *tp = (struct trace_probe *)call->data;
@@ -1107,35 +1098,35 @@ static int register_probe_event(struct trace_probe *tp)
/* Initialize ftrace_event_call */
call->system = "kprobes";
if (probe_is_return(tp)) {
- call->event = &kretprobe_trace_event;
- call->id = TRACE_KRETPROBE;
+ tp->event.trace = print_kretprobe_event;
call->raw_init = probe_event_raw_init;
call->show_format = kretprobe_event_show_format;
call->define_fields = kretprobe_event_define_fields;
} else {
- call->event = &kprobe_trace_event;
- call->id = TRACE_KPROBE;
+ tp->event.trace = print_kprobe_event;
call->raw_init = probe_event_raw_init;
call->show_format = kprobe_event_show_format;
call->define_fields = kprobe_event_define_fields;
}
+ call->event = &tp->event;
+ call->id = register_ftrace_event(&tp->event);
+ if (!call->id)
+ return -ENODEV;
call->enabled = 1;
call->regfunc = probe_event_enable;
call->unregfunc = probe_event_disable;
call->data = tp;
ret = trace_add_event_call(call);
- if (ret)
+ if (ret) {
pr_info("Failed to register kprobe event: %s\n", call->name);
+ unregister_ftrace_event(&tp->event);
+ }
return ret;
}

static void unregister_probe_event(struct trace_probe *tp)
{
- /*
- * Prevent to unregister event itself because the event is shared
- * among other probes.
- */
- tp->call.event = NULL;
+ /* tp->event is unregistered in trace_remove_event_call() */
trace_remove_event_call(&tp->call);
}

@@ -1144,18 +1135,6 @@ static __init int init_kprobe_trace(void)
{
struct dentry *d_tracer;
struct dentry *entry;
- int ret;
-
- ret = register_ftrace_event(&kprobe_trace_event);
- if (!ret) {
- pr_warning("Could not register kprobe_trace_event type.\n");
- return 0;
- }
- ret = register_ftrace_event(&kretprobe_trace_event);
- if (!ret) {
- pr_warning("Could not register kretprobe_trace_event type.\n");
- return 0;
- }

d_tracer = tracing_init_dentry();
if (!d_tracer)

--
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com
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