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Subject[PATCH tracing/kprobes 4/7] tracing/kprobes: Add event profiling support
Date
Add *probe_profile_enable/disable for supporting perf tool
when CONFIG_PROFILE_EVENT=y.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.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: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
---
Documentation/trace/kprobetrace.txt | 4 +
kernel/trace/trace_kprobe.c | 110 ++++++++++++++++++++++++++++++++++-
2 files changed, 111 insertions(+), 3 deletions(-)
diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt
index db55318..8f882eb 100644
--- a/Documentation/trace/kprobetrace.txt
+++ b/Documentation/trace/kprobetrace.txt
@@ -62,13 +62,15 @@ enabled:
You can enable/disable the probe by writing 1 or 0 on it.

format:
- It shows the format of this probe event. It also shows aliases of arguments
+ This shows the format of this probe event. It also shows aliases of arguments
which you specified to kprobe_events.

filter:
You can write filtering rules of this event. And you can use both of aliase
names and field names for describing filters.

+id:
+ This shows the id of this probe event.

Event Profiling
---------------
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 902a148..21ffb5e 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -28,6 +28,7 @@
#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/ptrace.h>
+#include <linux/perf_counter.h>

#include "trace.h"
#include "trace_output.h"
@@ -280,6 +281,7 @@ static struct trace_probe *alloc_trace_probe(const char *event,
} else
tp->rp.kp.addr = addr;

+ /* Set handler here for checking whether this probe is return or not. */
if (is_return)
tp->rp.handler = kretprobe_trace_func;
else
@@ -927,10 +929,13 @@ static int probe_event_enable(struct ftrace_event_call *call)
{
struct trace_probe *tp = (struct trace_probe *)call->data;

- if (probe_is_return(tp))
+ if (probe_is_return(tp)) {
+ tp->rp.handler = kretprobe_trace_func;
return enable_kretprobe(&tp->rp);
- else
+ } else {
+ tp->rp.kp.pre_handler = kprobe_trace_func;
return enable_kprobe(&tp->rp.kp);
+ }
}

static void probe_event_disable(struct ftrace_event_call *call)
@@ -1103,6 +1108,101 @@ static int kretprobe_event_show_format(struct ftrace_event_call *call,
"func, ret_ip");
}

+#ifdef CONFIG_EVENT_PROFILE
+
+/* Kprobe profile handler */
+static __kprobes int kprobe_profile_func(struct kprobe *kp,
+ struct pt_regs *regs)
+{
+ struct trace_probe *tp = container_of(kp, struct trace_probe, rp.kp);
+ struct ftrace_event_call *call = &tp->call;
+ struct kprobe_trace_entry *entry;
+ int size, i, pc;
+ unsigned long irq_flags;
+
+ local_save_flags(irq_flags);
+ pc = preempt_count();
+
+ size = SIZEOF_KPROBE_TRACE_ENTRY(tp->nr_args);
+
+ do {
+ char raw_data[size];
+ struct trace_entry *ent;
+
+ *(u64 *)(&raw_data[size - sizeof(u64)]) = 0ULL;
+ entry = (struct kprobe_trace_entry *)raw_data;
+ ent = &entry->ent;
+
+ tracing_generic_entry_update(ent, irq_flags, pc);
+ ent->type = call->id;
+ entry->nargs = tp->nr_args;
+ entry->ip = (unsigned long)kp->addr;
+ for (i = 0; i < tp->nr_args; i++)
+ entry->args[i] = call_fetch(&tp->args[i], regs);
+ perf_tpcounter_event(call->id, entry->ip, 1, entry, size);
+ } while (0);
+ return 0;
+}
+
+/* Kretprobe profile handler */
+static __kprobes int kretprobe_profile_func(struct kretprobe_instance *ri,
+ struct pt_regs *regs)
+{
+ struct trace_probe *tp = container_of(ri->rp, struct trace_probe, rp);
+ struct ftrace_event_call *call = &tp->call;
+ struct kretprobe_trace_entry *entry;
+ int size, i, pc;
+ unsigned long irq_flags;
+
+ local_save_flags(irq_flags);
+ pc = preempt_count();
+
+ size = SIZEOF_KRETPROBE_TRACE_ENTRY(tp->nr_args);
+
+ do {
+ char raw_data[size];
+ struct trace_entry *ent;
+
+ *(u64 *)(&raw_data[size - sizeof(u64)]) = 0ULL;
+ entry = (struct kretprobe_trace_entry *)raw_data;
+ ent = &entry->ent;
+
+ tracing_generic_entry_update(ent, irq_flags, pc);
+ ent->type = call->id;
+ entry->nargs = tp->nr_args;
+ entry->func = (unsigned long)tp->rp.kp.addr;
+ entry->ret_ip = (unsigned long)ri->ret_addr;
+ for (i = 0; i < tp->nr_args; i++)
+ entry->args[i] = call_fetch(&tp->args[i], regs);
+ perf_tpcounter_event(call->id, entry->ret_ip, 1, entry, size);
+ } while (0);
+ return 0;
+}
+
+static int probe_profile_enable(struct ftrace_event_call *call)
+{
+ struct trace_probe *tp = (struct trace_probe *)call->data;
+
+ if (atomic_inc_return(&call->profile_count))
+ return 0;
+
+ if (probe_is_return(tp)) {
+ tp->rp.handler = kretprobe_profile_func;
+ return enable_kretprobe(&tp->rp);
+ } else {
+ tp->rp.kp.pre_handler = kprobe_profile_func;
+ return enable_kprobe(&tp->rp.kp);
+ }
+}
+
+static void probe_profile_disable(struct ftrace_event_call *call)
+{
+ if (atomic_add_negative(-1, &call->profile_count))
+ probe_event_disable(call);
+}
+
+#endif /* CONFIG_EVENT_PROFILE */
+
static int register_probe_event(struct trace_probe *tp)
{
struct ftrace_event_call *call = &tp->call;
@@ -1128,6 +1228,12 @@ static int register_probe_event(struct trace_probe *tp)
call->enabled = 1;
call->regfunc = probe_event_enable;
call->unregfunc = probe_event_disable;
+
+#ifdef CONFIG_EVENT_PROFILE
+ atomic_set(&call->profile_count, -1);
+ call->profile_enable = probe_profile_enable;
+ call->profile_disable = probe_profile_disable;
+#endif
call->data = tp;
ret = trace_add_event_call(call);
if (ret) {

--
Masami Hiramatsu

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

e-mail: mhiramat@redhat.com


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