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tracing/kprobes: Add probe handler dispatcher to support perf and ftr…
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…ace concurrent use

Add kprobe_dispatcher and kretprobe_dispatcher to dispatch event
in both profile and tracing handlers.

This allows simultaneous kprobe uses by ftrace and perf.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
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: 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: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <20090914204920.18779.57555.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
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Masami Hiramatsu authored and Frederic Weisbecker committed Sep 17, 2009
1 parent 4fead8e commit 50d7805
Showing 1 changed file with 63 additions and 22 deletions.
85 changes: 63 additions & 22 deletions kernel/trace/trace_kprobe.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -185,10 +185,15 @@ struct probe_arg {
const char *name;
};

/* Flags for trace_probe */
#define TP_FLAG_TRACE 1
#define TP_FLAG_PROFILE 2

struct trace_probe {
struct list_head list;
struct kretprobe rp; /* Use rp.kp for kprobe use */
unsigned long nhit;
unsigned int flags; /* For TP_FLAG_* */
const char *symbol; /* symbol name */
struct ftrace_event_call call;
struct trace_event event;
Expand All @@ -200,10 +205,6 @@ struct trace_probe {
(offsetof(struct trace_probe, args) + \
(sizeof(struct probe_arg) * (n)))

static int kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs);
static int kretprobe_trace_func(struct kretprobe_instance *ri,
struct pt_regs *regs);

static __kprobes int probe_is_return(struct trace_probe *tp)
{
return tp->rp.handler != NULL;
Expand Down Expand Up @@ -263,6 +264,10 @@ static void unregister_probe_event(struct trace_probe *tp);
static DEFINE_MUTEX(probe_lock);
static LIST_HEAD(probe_list);

static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs);
static int kretprobe_dispatcher(struct kretprobe_instance *ri,
struct pt_regs *regs);

/*
* Allocate new trace_probe and initialize it (including kprobes).
*/
Expand All @@ -288,11 +293,10 @@ static struct trace_probe *alloc_trace_probe(const char *group,
} 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;
tp->rp.handler = kretprobe_dispatcher;
else
tp->rp.kp.pre_handler = kprobe_trace_func;
tp->rp.kp.pre_handler = kprobe_dispatcher;

if (!event)
goto error;
Expand Down Expand Up @@ -379,6 +383,7 @@ static int register_trace_probe(struct trace_probe *tp)
goto end;
}

tp->flags = TP_FLAG_TRACE;
if (probe_is_return(tp))
ret = register_kretprobe(&tp->rp);
else
Expand Down Expand Up @@ -987,23 +992,24 @@ static int probe_event_enable(struct ftrace_event_call *call)
{
struct trace_probe *tp = (struct trace_probe *)call->data;

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

static void probe_event_disable(struct ftrace_event_call *call)
{
struct trace_probe *tp = (struct trace_probe *)call->data;

if (probe_is_return(tp))
disable_kretprobe(&tp->rp);
else
disable_kprobe(&tp->rp.kp);
tp->flags &= ~TP_FLAG_TRACE;
if (!(tp->flags & (TP_FLAG_TRACE | TP_FLAG_PROFILE))) {
if (probe_is_return(tp))
disable_kretprobe(&tp->rp);
else
disable_kprobe(&tp->rp.kp);
}
}

static int probe_event_raw_init(struct ftrace_event_call *event_call)
Expand Down Expand Up @@ -1212,22 +1218,57 @@ static int probe_profile_enable(struct ftrace_event_call *call)
if (atomic_inc_return(&call->profile_count))
return 0;

if (probe_is_return(tp)) {
tp->rp.handler = kretprobe_profile_func;
tp->flags |= TP_FLAG_PROFILE;
if (probe_is_return(tp))
return enable_kretprobe(&tp->rp);
} else {
tp->rp.kp.pre_handler = kprobe_profile_func;
else
return enable_kprobe(&tp->rp.kp);
}
}

static void probe_profile_disable(struct ftrace_event_call *call)
{
struct trace_probe *tp = (struct trace_probe *)call->data;

if (atomic_add_negative(-1, &call->profile_count))
probe_event_disable(call);
tp->flags &= ~TP_FLAG_PROFILE;

if (!(tp->flags & (TP_FLAG_TRACE | TP_FLAG_PROFILE))) {
if (probe_is_return(tp))
disable_kretprobe(&tp->rp);
else
disable_kprobe(&tp->rp.kp);
}
}
#endif /* CONFIG_EVENT_PROFILE */


static __kprobes
int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs)
{
struct trace_probe *tp = container_of(kp, struct trace_probe, rp.kp);

if (tp->flags & TP_FLAG_TRACE)
kprobe_trace_func(kp, regs);
#ifdef CONFIG_EVENT_PROFILE
if (tp->flags & TP_FLAG_PROFILE)
kprobe_profile_func(kp, regs);
#endif /* CONFIG_EVENT_PROFILE */
return 0; /* We don't tweek kernel, so just return 0 */
}

static __kprobes
int kretprobe_dispatcher(struct kretprobe_instance *ri, struct pt_regs *regs)
{
struct trace_probe *tp = container_of(ri->rp, struct trace_probe, rp);

if (tp->flags & TP_FLAG_TRACE)
kretprobe_trace_func(ri, regs);
#ifdef CONFIG_EVENT_PROFILE
if (tp->flags & TP_FLAG_PROFILE)
kretprobe_profile_func(ri, regs);
#endif /* CONFIG_EVENT_PROFILE */
return 0; /* We don't tweek kernel, so just return 0 */
}

static int register_probe_event(struct trace_probe *tp)
{
Expand Down

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