On Thu, Jun 20, 2024 at 2:34 PM Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote:
>
> Add test coverage for reservations beyond the ring buffer size in order
> to validate that bpf_ringbuf_reserve() rejects the request with NULL, all
> other ring buffer tests keep passing as well:
>
> # ./vmtest.sh -- ./test_progs -t ringbuf
> [...]
> ./test_progs -t ringbuf
> [ 1.165434] bpf_testmod: loading out-of-tree module taints kernel.
> [ 1.165825] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel
> [ 1.284001] tsc: Refined TSC clocksource calibration: 3407.982 MHz
> [ 1.286871] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x311fc34e357, max_idle_ns: 440795379773 ns
> [ 1.289555] clocksource: Switched to clocksource tsc
> #274/1 ringbuf/ringbuf:OK
> #274/2 ringbuf/ringbuf_n:OK
> #274/3 ringbuf/ringbuf_map_key:OK
> #274/4 ringbuf/ringbuf_write:OK
> #274 ringbuf:OK
> #275 ringbuf_multi:OK
> [...]
>
> Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
> ---
> tools/testing/selftests/bpf/Makefile | 2 +-
> .../selftests/bpf/prog_tests/ringbuf.c | 46 +++++++++++++++++++
> .../selftests/bpf/progs/test_ringbuf_write.c | 42 +++++++++++++++++
> 3 files changed, 89 insertions(+), 1 deletion(-)
> create mode 100644 tools/testing/selftests/bpf/progs/test_ringbuf_write.c
>
> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> index e0b3887b3d2d..dd49c1d23a60 100644
> --- a/tools/testing/selftests/bpf/Makefile
> +++ b/tools/testing/selftests/bpf/Makefile
> @@ -457,7 +457,7 @@ LINKED_SKELS := test_static_linked.skel.h linked_funcs.skel.h \
> LSKELS := fentry_test.c fexit_test.c fexit_sleep.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_n.c test_ringbuf_map_key.c
> + test_ringbuf_n.c test_ringbuf_map_key.c test_ringbuf_write.c
>
> # Generate both light skeleton and libbpf skeleton for these
> LSKELS_EXTRA := test_ksyms_module.c test_ksyms_weak.c kfunc_call_test.c \
> diff --git a/tools/testing/selftests/bpf/prog_tests/ringbuf.c b/tools/testing/selftests/bpf/prog_tests/ringbuf.c
> index 4c6f42dae409..3eddd5e9c10b 100644
> --- a/tools/testing/selftests/bpf/prog_tests/ringbuf.c
> +++ b/tools/testing/selftests/bpf/prog_tests/ringbuf.c
> @@ -12,9 +12,11 @@
> #include <sys/sysinfo.h>
> #include <linux/perf_event.h>
> #include <linux/ring_buffer.h>
> +
> #include "test_ringbuf.lskel.h"
> #include "test_ringbuf_n.lskel.h"
> #include "test_ringbuf_map_key.lskel.h"
> +#include "test_ringbuf_write.lskel.h"
>
> #define EDONE 7777
>
> @@ -84,6 +86,48 @@ static void *poll_thread(void *input)
> return (void *)(long)ring_buffer__poll(ringbuf, timeout);
> }
>
> +static void ringbuf_write_subtest(void)
> +{
> + struct test_ringbuf_write_lskel *skel;
> + int page_size = getpagesize();
> + size_t *mmap_ptr;
> + int err, rb_fd;
> +
> + skel = test_ringbuf_write_lskel__open();
> + if (CHECK(!skel, "skel_open", "skeleton open failed\n"))
> + return;
> +
> + skel->maps.ringbuf.max_entries = 0x4000;
> +
> + err = test_ringbuf_write_lskel__load(skel);
> + if (CHECK(err != 0, "skel_load", "skeleton load failed\n"))
here and above, let's not add CHECK(), let's stick to ASSERT_xxx()
> + goto cleanup;
> +
> + rb_fd = skel->maps.ringbuf.map_fd;
> +
> + mmap_ptr = mmap(NULL, page_size, PROT_READ | PROT_WRITE, MAP_SHARED, rb_fd, 0);
> + ASSERT_OK_PTR(mmap_ptr, "rw_cons_pos");
> + *mmap_ptr = 0x3000;
> +
> + skel->bss->pid = getpid();
> +
> + ringbuf = ring_buffer__new(skel->maps.ringbuf.map_fd,
> + process_sample, NULL, NULL);
> + if (CHECK(!ringbuf, "ringbuf_create", "failed to create ringbuf\n"))
> + goto cleanup;
> +
> + err = test_ringbuf_write_lskel__attach(skel);
> + if (CHECK(err, "skel_attach", "skeleton attachment failed: %d\n", err))
> + goto cleanup;
> +
> + trigger_samples();
> + ASSERT_GE(skel->bss->discarded, 1, "discarded");
> + ASSERT_EQ(skel->bss->passed, 0, "passed");
> +cleanup:
> + ring_buffer__free(ringbuf);
> + test_ringbuf_write_lskel__destroy(skel);
> +}
> +
> static void ringbuf_subtest(void)
> {
> const size_t rec_sz = BPF_RINGBUF_HDR_SZ + sizeof(struct sample);
> @@ -451,4 +495,6 @@ void test_ringbuf(void)
> ringbuf_n_subtest();
> if (test__start_subtest("ringbuf_map_key"))
> ringbuf_map_key_subtest();
> + if (test__start_subtest("ringbuf_write"))
> + ringbuf_write_subtest();
> }
> diff --git a/tools/testing/selftests/bpf/progs/test_ringbuf_write.c b/tools/testing/selftests/bpf/progs/test_ringbuf_write.c
> new file mode 100644
> index 000000000000..c6c67238a7c8
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_ringbuf_write.c
> @@ -0,0 +1,42 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <linux/bpf.h>
> +#include <bpf/bpf_helpers.h>
> +#include "bpf_misc.h"
> +
> +char _license[] SEC("license") = "GPL";
> +
> +struct {
> + __uint(type, BPF_MAP_TYPE_RINGBUF);
> +} ringbuf SEC(".maps");
> +
> +long discarded, passed;
> +int pid;
> +
> +SEC("fentry/" SYS_PREFIX "sys_getpgid")
> +int test_ringbuf_write(void *ctx)
> +{
> + int *foo, cur_pid = bpf_get_current_pid_tgid() >> 32;
> + void *sample1, *sample2;
> +
> + if (cur_pid != pid)
> + return 0;
> +
> + sample1 = bpf_ringbuf_reserve(&ringbuf, 0x3000, 0);
> + if (!sample1)
> + return 0;
> + /* first one can pass */
> + sample2 = bpf_ringbuf_reserve(&ringbuf, 0x3000, 0);
> + if (!sample2) {
> + bpf_ringbuf_discard(sample1, 0);
> + __sync_fetch_and_add(&discarded, 1);
> + return 0;
> + }
> + /* second one must not */
> + __sync_fetch_and_add(&passed, 1);
> + foo = sample2 + 4084;
> + *foo = 256;
> + bpf_ringbuf_discard(sample1, 0);
> + bpf_ringbuf_discard(sample2, 0);
> + return 0;
> +}
> --
> 2.43.0
>
>
