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authorSong Liu <songliubraving@fb.com>2018-10-01 22:36:36 -0700
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2018-10-10 22:14:17 -0400
commita6ca88b241d5e929e6e60b12ad8cd288f0ffa256 (patch)
treeabb90d380a5c6e7ecd190b3a67745058b96fe564 /kernel/events
parent5a5e3d3ceae2121590d67258a4e658d938b4a46d (diff)
downloadlinux-a6ca88b241d5e929e6e60b12ad8cd288f0ffa256.tar.bz2
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: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-and-tested-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com> Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/events')
-rw-r--r--kernel/events/core.c49
1 files changed, 39 insertions, 10 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index c80549bf82c6..65b30773af3e 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -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;