Commit a6ca88b2 authored by Song Liu's avatar Song Liu Committed by Steven Rostedt (VMware)
Browse files

trace_uprobe: support reference counter in fd-based uprobe 

This patch enables uprobes with reference counter in fd-based uprobe.
Highest 32 bits of perf_event_attr.config is used to stored offset
of the reference count (semaphore).

Format information in /sys/bus/event_source/devices/uprobe/format/ is
updated to reflect this new feature.

Link: http://lkml.kernel.org/r/20181002053636.1896903-1-songliubraving@fb.com



Cc: Oleg Nesterov <oleg@redhat.com>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-and-tested-by: default avatarRavi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: default avatarSong Liu <songliubraving@fb.com>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 5a5e3d3c

include/linux/trace_events.h

+2 −1
Original line number Diff line number Diff line
@@ -575,7 +575,8 @@ extern int bpf_get_kprobe_info(const struct perf_event *event, 
			       bool perf_type_tracepoint);

#endif

#ifdef CONFIG_UPROBE_EVENTS

extern int  perf_uprobe_init(struct perf_event *event, bool is_retprobe);

extern int  perf_uprobe_init(struct perf_event *event,

			     unsigned long ref_ctr_offset, bool is_retprobe);

extern void perf_uprobe_destroy(struct perf_event *event);

extern int bpf_get_uprobe_info(const struct perf_event *event,

			       u32 *fd_type, const char **filename,

kernel/events/core.c

+39 −10
Original line number Diff line number Diff line
@@ -8368,30 +8368,39 @@ static struct pmu perf_tracepoint = { 
 *

 * PERF_PROBE_CONFIG_IS_RETPROBE if set, create kretprobe/uretprobe

 *                               if not set, create kprobe/uprobe

 *

 * The following values specify a reference counter (or semaphore in the

 * terminology of tools like dtrace, systemtap, etc.) Userspace Statically

 * Defined Tracepoints (USDT). Currently, we use 40 bit for the offset.

 *

 * PERF_UPROBE_REF_CTR_OFFSET_BITS	# of bits in config as th offset

 * PERF_UPROBE_REF_CTR_OFFSET_SHIFT	# of bits to shift left

 */

enum perf_probe_config {

	PERF_PROBE_CONFIG_IS_RETPROBE = 1U << 0,  /* [k,u]retprobe */

	PERF_UPROBE_REF_CTR_OFFSET_BITS = 32,

	PERF_UPROBE_REF_CTR_OFFSET_SHIFT = 64 - PERF_UPROBE_REF_CTR_OFFSET_BITS,

};



PMU_FORMAT_ATTR(retprobe, "config:0");

#endif



static struct attribute *probe_attrs[] = {

#ifdef CONFIG_KPROBE_EVENTS

static struct attribute *kprobe_attrs[] = {

	&format_attr_retprobe.attr,

	NULL,

};



static struct attribute_group probe_format_group = {

static struct attribute_group kprobe_format_group = {

	.name = "format",

	.attrs = probe_attrs,

	.attrs = kprobe_attrs,

};



static const struct attribute_group *probe_attr_groups[] = {

	&probe_format_group,

static const struct attribute_group *kprobe_attr_groups[] = {

	&kprobe_format_group,

	NULL,

};

#endif



#ifdef CONFIG_KPROBE_EVENTS

static int perf_kprobe_event_init(struct perf_event *event);

static struct pmu perf_kprobe = {

	.task_ctx_nr	= perf_sw_context,
@@ -8401,7 +8410,7 @@ static struct pmu perf_kprobe = { 
	.start		= perf_swevent_start,

	.stop		= perf_swevent_stop,

	.read		= perf_swevent_read,

	.attr_groups	= probe_attr_groups,

	.attr_groups	= kprobe_attr_groups,

};



static int perf_kprobe_event_init(struct perf_event *event)
@@ -8433,6 +8442,24 @@ static int perf_kprobe_event_init(struct perf_event *event) 
#endif /* CONFIG_KPROBE_EVENTS */



#ifdef CONFIG_UPROBE_EVENTS

PMU_FORMAT_ATTR(ref_ctr_offset, "config:32-63");



static struct attribute *uprobe_attrs[] = {

	&format_attr_retprobe.attr,

	&format_attr_ref_ctr_offset.attr,

	NULL,

};



static struct attribute_group uprobe_format_group = {

	.name = "format",

	.attrs = uprobe_attrs,

};



static const struct attribute_group *uprobe_attr_groups[] = {

	&uprobe_format_group,

	NULL,

};



static int perf_uprobe_event_init(struct perf_event *event);

static struct pmu perf_uprobe = {

	.task_ctx_nr	= perf_sw_context,
@@ -8442,12 +8469,13 @@ static struct pmu perf_uprobe = { 
	.start		= perf_swevent_start,

	.stop		= perf_swevent_stop,

	.read		= perf_swevent_read,

	.attr_groups	= probe_attr_groups,

	.attr_groups	= uprobe_attr_groups,

};



static int perf_uprobe_event_init(struct perf_event *event)

{

	int err;

	unsigned long ref_ctr_offset;

	bool is_retprobe;



	if (event->attr.type != perf_uprobe.type)
@@ -8463,7 +8491,8 @@ static int perf_uprobe_event_init(struct perf_event *event) 
		return -EOPNOTSUPP;



	is_retprobe = event->attr.config & PERF_PROBE_CONFIG_IS_RETPROBE;

	err = perf_uprobe_init(event, is_retprobe);

	ref_ctr_offset = event->attr.config >> PERF_UPROBE_REF_CTR_OFFSET_SHIFT;

	err = perf_uprobe_init(event, ref_ctr_offset, is_retprobe);

	if (err)

		return err;

kernel/trace/trace_event_perf.c

+4 −3
Original line number Diff line number Diff line
@@ -290,7 +290,8 @@ void perf_kprobe_destroy(struct perf_event *p_event) 
#endif /* CONFIG_KPROBE_EVENTS */



#ifdef CONFIG_UPROBE_EVENTS

int perf_uprobe_init(struct perf_event *p_event, bool is_retprobe)

int perf_uprobe_init(struct perf_event *p_event,

		     unsigned long ref_ctr_offset, bool is_retprobe)

{

	int ret;

	char *path = NULL;
@@ -312,8 +313,8 @@ int perf_uprobe_init(struct perf_event *p_event, bool is_retprobe) 
		goto out;

	}



	tp_event = create_local_trace_uprobe(

		path, p_event->attr.probe_offset, is_retprobe);

	tp_event = create_local_trace_uprobe(path, p_event->attr.probe_offset,

					     ref_ctr_offset, is_retprobe);

	if (IS_ERR(tp_event)) {

		ret = PTR_ERR(tp_event);

		goto out;

kernel/trace/trace_probe.h

+2 −1
Original line number Diff line number Diff line
@@ -412,6 +412,7 @@ create_local_trace_kprobe(char *func, void *addr, unsigned long offs, 
extern void destroy_local_trace_kprobe(struct trace_event_call *event_call);



extern struct trace_event_call *

create_local_trace_uprobe(char *name, unsigned long offs, bool is_return);

create_local_trace_uprobe(char *name, unsigned long offs,

			  unsigned long ref_ctr_offset, bool is_return);

extern void destroy_local_trace_uprobe(struct trace_event_call *event_call);

#endif

kernel/trace/trace_uprobe.c

+3 −1
Original line number Diff line number Diff line
@@ -1405,7 +1405,8 @@ static int unregister_uprobe_event(struct trace_uprobe *tu) 


#ifdef CONFIG_PERF_EVENTS

struct trace_event_call *

create_local_trace_uprobe(char *name, unsigned long offs, bool is_return)

create_local_trace_uprobe(char *name, unsigned long offs,

			  unsigned long ref_ctr_offset, bool is_return)

{

	struct trace_uprobe *tu;

	struct path path;
@@ -1437,6 +1438,7 @@ create_local_trace_uprobe(char *name, unsigned long offs, bool is_return) 


	tu->offset = offs;

	tu->path = path;

	tu->ref_ctr_offset = ref_ctr_offset;

	tu->filename = kstrdup(name, GFP_KERNEL);

	init_trace_event_call(tu, &tu->tp.call);

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