Hi Peter,
> On Sep 24, 2018, at 2:12 PM, Song Liu <songliubrav...@fb.com> wrote:
>
> This patch enables uprobes with reference counter in fd-based uprobe.
> Highest 40 bits of perf_event_attr.config is used to stored offset
> of the reference counter (semaphore).
>
> Format information in /sys/bus/event_source/devices/uprobe/format/ is
> updated to reflect this new feature.
>
> Signed-off-by: Song Liu <songliubrav...@fb.com>
> Reviewed-and-tested-by: Ravi Bangoria <ravi.bango...@linux.ibm.com>
> Cc: Masami Hiramatsu <mhira...@kernel.org>
> Cc: Oleg Nesterov <o...@redhat.com>
> Cc: Srikar Dronamraju <sri...@linux.vnet.ibm.com>
> Cc: Naveen N. Rao <naveen.n....@linux.vnet.ibm.com>
> Cc: Steven Rostedt (VMware) <rost...@goodmis.org>
> ---
> include/linux/trace_events.h | 3 +-
> kernel/events/core.c | 49 ++++++++++++++++++++++++++-------
> kernel/trace/trace_event_perf.c | 7 +++--
> kernel/trace/trace_probe.h | 3 +-
> kernel/trace/trace_uprobe.c | 4 ++-
> 5 files changed, 50 insertions(+), 16 deletions(-)
>
> diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
> index 78a010e19ed4..4130a5497d40 100644
> --- a/include/linux/trace_events.h
> +++ b/include/linux/trace_events.h
> @@ -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,
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index c80549bf82c6..a4ad5235ec9b 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 = 40,
> + 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:63-24");
I guess you meant this part? This is for uprobe only, so I put
it here.
Thanks,
Song
> +
> +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,
> };
>
