From a6ca88b241d5e929e6e60b12ad8cd288f0ffa256 Mon Sep 17 00:00:00 2001 From: Song Liu Date: Mon, 1 Oct 2018 22:36:36 -0700 Subject: 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 Acked-by: Peter Zijlstra (Intel) Reviewed-and-tested-by: Ravi Bangoria Signed-off-by: Song Liu Signed-off-by: Steven Rostedt (VMware) --- kernel/events/core.c | 49 +++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 39 insertions(+), 10 deletions(-) (limited to 'kernel/events') 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; -- cgit v1.2.3