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selftests/bpf: Test access to ringbuf position with map pointer 

Add the testing to access the bpf_ringbuf with the map pointer.
"consumer_pos" and "producer_pos" is accessed in this testing. We reserve
128 bytes in the ringbuf to test the producer_pos, which should be
"128 + BPF_RINGBUF_HDR_SZ".

It will be helpful if we want to evaluate the usage of the ringbuf in bpf
prog with the consumer and producer position.

Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Leon Hwang <leon.hwang@linux.dev>
Link: https://lore.kernel.org/bpf/20260331070434.10037-1-dongml2@chinatelecom.cn
master
Menglong Dong 2026-03-31 15:04:34 +08:00 committed by Andrii Nakryiko
parent f9a80c7ce4
commit 3e6475dc60
1 changed files with 17 additions and 0 deletions
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17
tools/testing/selftests/bpf/progs/map_ptr_kern.c
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@ -647,8 +647,14 @@ static inline int check_devmap_hash(void)
return 1;
}
struct bpf_ringbuf {
unsigned long consumer_pos;
unsigned long producer_pos;
} __attribute__((preserve_access_index));
struct bpf_ringbuf_map {
struct bpf_map map;
struct bpf_ringbuf *rb;
} __attribute__((preserve_access_index));
struct {
@ -659,9 +665,20 @@ static inline int check_ringbuf(void)
{
struct bpf_ringbuf_map *ringbuf = (struct bpf_ringbuf_map *)&m_ringbuf;
struct bpf_map *map = (struct bpf_map *)&m_ringbuf;
struct bpf_ringbuf *rb;
void *ptr;
VERIFY(check(&ringbuf->map, map, 0, 0, page_size));
ptr = bpf_ringbuf_reserve(&m_ringbuf, 128, 0);
VERIFY(ptr);
bpf_ringbuf_discard(ptr, 0);
rb = ringbuf->rb;
VERIFY(rb);
VERIFY(rb->consumer_pos == 0);
VERIFY(rb->producer_pos == 128 + BPF_RINGBUF_HDR_SZ);
return 1;
}