Add tests to confirm behavior of overwritable BPF ring buffer, particularly the oldest data being overwritten by newest ones.
Signed-off-by: Francis Laniel flaniel@linux.microsoft.com --- tools/testing/selftests/bpf/Makefile | 5 +- .../bpf/prog_tests/ringbuf_overwritable.c | 158 ++++++++++++++++++ .../bpf/progs/test_ringbuf_overwritable.c | 61 +++++++ 3 files changed, 222 insertions(+), 2 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/ringbuf_overwritable.c create mode 100644 tools/testing/selftests/bpf/progs/test_ringbuf_overwritable.c
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 8d59ec7f4c2d..96e95dcfc982 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -351,8 +351,9 @@ LINKED_SKELS := test_static_linked.skel.h linked_funcs.skel.h \ test_usdt.skel.h
LSKELS := kfunc_call_test.c fentry_test.c fexit_test.c fexit_sleep.c \ - test_ringbuf.c atomics.c trace_printk.c trace_vprintk.c \ - map_ptr_kern.c core_kern.c core_kern_overflow.c + test_ringbuf.c test_ringbuf_overwritable.c atomics.c \ + trace_printk.c trace_vprintk.c map_ptr_kern.c \ + core_kern.c core_kern_overflow.c # Generate both light skeleton and libbpf skeleton for these LSKELS_EXTRA := test_ksyms_module.c test_ksyms_weak.c kfunc_call_test_subprog.c SKEL_BLACKLIST += $$(LSKELS) diff --git a/tools/testing/selftests/bpf/prog_tests/ringbuf_overwritable.c b/tools/testing/selftests/bpf/prog_tests/ringbuf_overwritable.c new file mode 100644 index 000000000000..b5ec1e62f761 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/ringbuf_overwritable.c @@ -0,0 +1,158 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE +#include <linux/compiler.h> +#include <asm/barrier.h> +#include <test_progs.h> +#include <sys/mman.h> +#include <sys/epoll.h> +#include <time.h> +#include <sched.h> +#include <signal.h> +#include <pthread.h> +#include <sys/sysinfo.h> +#include <linux/perf_event.h> +#include <linux/ring_buffer.h> +#include "test_ringbuf_overwritable.lskel.h" + +struct sample { + int count; + /* + * filler size will be computed to have 8 samples in a 4096 bytes long + * buffer. + */ + char filler[4096 / 8 - sizeof(int) - 8]; +}; + +struct ring { + ring_buffer_sample_fn sample_cb; + __u8 overwritable: 1, + __reserved: 7; + void *ctx; + void *data; + unsigned long *consumer_pos; + unsigned long *producer_pos; + unsigned long mask; + int map_fd; +}; + +struct ring_buffer { + struct epoll_event *events; + struct ring *rings; + size_t page_size; + int epoll_fd; + int ring_cnt; +}; + +static int duration; +static struct test_ringbuf_overwritable_lskel *skel; + +void test_ringbuf_overwritable(void) +{ + const size_t rec_sz = BPF_RINGBUF_HDR_SZ + sizeof(struct sample); + int page_size = getpagesize(); + int sample_cnt = 0, sample_read = 0; + unsigned long mask = page_size - 1; + struct ring_buffer *ringbuf; + int err, *len_ptr, len; + struct sample *sample; + long read_pos; + void *data_ptr; + + skel = test_ringbuf_overwritable_lskel__open(); + if (CHECK(!skel, "skel_open", "skeleton open failed\n")) + return; + + skel->maps.ringbuf.max_entries = page_size; + + err = test_ringbuf_overwritable_lskel__load(skel); + if (CHECK(err != 0, "skel_load", "skeleton load failed\n")) + goto cleanup; + + /* only trigger BPF program for current process */ + skel->bss->pid = getpid(); + + ringbuf = ring_buffer__new(skel->maps.ringbuf.map_fd, NULL, NULL, NULL); + if (CHECK(!ringbuf, "ringbuf_create", "failed to create ringbuf\n")) + goto cleanup; + + /* There is only one ring in this ringbuf. */ + data_ptr = ringbuf->rings[0].data; + + err = test_ringbuf_overwritable_lskel__attach(skel); + if (CHECK(err, "skel_attach", "skeleton attachment failed: %d\n", err)) + goto cleanup; + + /* Trigger one sample. */ + syscall(__NR_getpgid); + sample_cnt++; + + CHECK(skel->bss->avail_data != -EINVAL, + "err_avail_size", "exp %d, got %ld\n", + -EINVAL, skel->bss->avail_data); + CHECK(skel->bss->ring_size != page_size, + "err_ring_size", "exp %ld, got %ld\n", + (long)page_size, skel->bss->ring_size); + CHECK(skel->bss->cons_pos != -EINVAL, + "err_cons_pos", "exp %d, got %ld\n", + -EINVAL, skel->bss->cons_pos); + CHECK(skel->bss->prod_pos != sample_cnt * -rec_sz, + "err_prod_pos", "exp %ld, got %ld\n", + sample_cnt * -rec_sz, skel->bss->prod_pos); + + len_ptr = data_ptr + (skel->bss->prod_pos & mask); + len = smp_load_acquire(len_ptr); + + CHECK(len != sizeof(struct sample), + "err_sample_len", "exp %ld, got %d\n", + sizeof(struct sample), len); + + sample = (void *)len_ptr + BPF_RINGBUF_HDR_SZ; + + CHECK(sample->count != sample_cnt, + "err_sample_cnt", "exp %d, got %d", + sample_cnt, sample->count); + + /* Trigger many samples, so we overwrite data */ + for (int i = 0; i < 16; i++) { + syscall(__NR_getpgid); + sample_cnt++; + } + + CHECK(skel->bss->avail_data != -EINVAL, + "err_avail_size", "exp %d, got %ld\n", + -EINVAL, skel->bss->avail_data); + CHECK(skel->bss->ring_size != page_size, + "err_ring_size", "exp %ld, got %ld\n", + (long)page_size, skel->bss->ring_size); + CHECK(skel->bss->cons_pos != -EINVAL, + "err_cons_pos", "exp %d, got %ld\n", + -EINVAL, skel->bss->cons_pos); + CHECK(skel->bss->prod_pos != sample_cnt * -rec_sz, + "err_prod_pos", "exp %ld, got %ld\n", + sample_cnt * -rec_sz, skel->bss->prod_pos); + + read_pos = skel->bss->prod_pos; + sample_read = 0; + while (read_pos - skel->bss->prod_pos < mask) { + len_ptr = data_ptr + (read_pos & mask); + len = smp_load_acquire(len_ptr); + + sample = (void *)len_ptr + BPF_RINGBUF_HDR_SZ; + + CHECK(sample->count != sample_cnt - sample_read, + "err_sample_cnt", "exp %d, got %d", + sample_cnt - sample_read, sample->count); + + sample_read++; + read_pos += round_up(len + BPF_RINGBUF_HDR_SZ, 8); + } + + CHECK(sample_read != page_size / rec_sz, + "err_sample_read", "exp %ld, got %d", + page_size / rec_sz, sample_read); + + test_ringbuf_overwritable_lskel__detach(skel); +cleanup: + ring_buffer__free(ringbuf); + test_ringbuf_overwritable_lskel__destroy(skel); +} diff --git a/tools/testing/selftests/bpf/progs/test_ringbuf_overwritable.c b/tools/testing/selftests/bpf/progs/test_ringbuf_overwritable.c new file mode 100644 index 000000000000..e28be35059b7 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_ringbuf_overwritable.c @@ -0,0 +1,61 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright (c) 2020 Facebook + +#include <linux/bpf.h> +#include <bpf/bpf_helpers.h> +#include "bpf_misc.h" + +char _license[] SEC("license") = "GPL"; + +struct sample { + int count; + /* + * filler size will be computed to have 8 samples in a 4096 bytes long + * buffer. + */ + char filler[4096 / 8 - sizeof(int) - BPF_RINGBUF_HDR_SZ]; +}; + +struct { + __uint(type, BPF_MAP_TYPE_RINGBUF); + __uint(map_flags, BFP_F_RB_OVERWRITABLE); +} ringbuf SEC(".maps"); + +/* inputs */ +int pid = 0; + +/* outputs */ +long avail_data = 0; +long ring_size = 0; +long cons_pos = 0; +long prod_pos = 0; + +static int count; + +SEC("fentry/" SYS_PREFIX "sys_getpgid") +int test_ringbuf_overwritable(void *ctx) +{ + int cur_pid = bpf_get_current_pid_tgid() >> 32; + struct sample *sample; + + if (cur_pid != pid) + return 0; + + sample = bpf_ringbuf_reserve(&ringbuf, sizeof(*sample), 0); + if (!sample) + return 0; + + __sync_fetch_and_add(&count, 1); + sample->count = count; + + bpf_printk("count: %d\n", count); + + bpf_ringbuf_submit(sample, 0); + + avail_data = bpf_ringbuf_query(&ringbuf, BPF_RB_AVAIL_DATA); + ring_size = bpf_ringbuf_query(&ringbuf, BPF_RB_RING_SIZE); + cons_pos = bpf_ringbuf_query(&ringbuf, BPF_RB_CONS_POS); + prod_pos = bpf_ringbuf_query(&ringbuf, BPF_RB_PROD_POS); + + return 0; +}