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Subject[PATCH V3 2/2] bpf: control all the perf events stored in PERF_EVENT_ARRAY maps
Date
This patch implements the function that controlling all the perf
events stored in PERF_EVENT_ARRAY maps by setting the parameter
'index' to maps max_entries.

Signed-off-by: Kaixu Xia <xiakaixu@huawei.com>
---
kernel/trace/bpf_trace.c | 20 ++++++++++++++++++--
1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 3175600..4b385863 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -229,13 +229,30 @@ static u64 bpf_perf_event_dump_control(u64 r1, u64 index, u64 flag, u64 r4, u64
struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
struct bpf_array *array = container_of(map, struct bpf_array, map);
struct perf_event *event;
+ int i;

- if (unlikely(index >= array->map.max_entries))
+ if (unlikely(index > array->map.max_entries))
return -E2BIG;

if (flag & BIT_FLAG_CHECK)
return -EINVAL;

+ if (index == array->map.max_entries) {
+ bool dump_control = flag & BIT_DUMP_CTL;
+
+ for (i = 0; i < array->map.max_entries; i++) {
+ event = (struct perf_event *)array->ptrs[i];
+ if (!event)
+ continue;
+
+ if (dump_control)
+ atomic_dec_if_positive(&event->dump_enable);
+ else
+ atomic_inc_unless_negative(&event->dump_enable);
+ }
+ return 0;
+ }
+
event = (struct perf_event *)array->ptrs[index];
if (!event)
return -ENOENT;
@@ -244,7 +261,6 @@ static u64 bpf_perf_event_dump_control(u64 r1, u64 index, u64 flag, u64 r4, u64
atomic_dec_if_positive(&event->dump_enable);
else
atomic_inc_unless_negative(&event->dump_enable);
-
return 0;
}

--
1.8.3.4


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