On Mon, Feb 10, 2020 at 12:09 PM Daniel Xu <dxu@xxxxxxxxx> wrote:
>
> Add a selftest to test:
>
> * default bpf_read_branch_records() behavior
> * BPF_F_GET_BRANCH_RECORDS_SIZE flag behavior
> * error path on non branch record perf events
> * using helper to write to stack
> * using helper to write to map
>
> On host with hardware counter support:
>
> # ./test_progs -t perf_branches
> #27/1 perf_branches_hw:OK
> #27/2 perf_branches_no_hw:OK
> #27 perf_branches:OK
> Summary: 1/2 PASSED, 0 SKIPPED, 0 FAILED
>
> On host without hardware counter support (VM):
>
> # ./test_progs -t perf_branches
> #27/1 perf_branches_hw:OK
> #27/2 perf_branches_no_hw:OK
> #27 perf_branches:OK
> Summary: 1/2 PASSED, 1 SKIPPED, 0 FAILED
>
> Also sync tools/include/uapi/linux/bpf.h.
>
> Signed-off-by: Daniel Xu <dxu@xxxxxxxxx>
> ---
> tools/include/uapi/linux/bpf.h | 25 ++-
> .../selftests/bpf/prog_tests/perf_branches.c | 182 ++++++++++++++++++
> .../selftests/bpf/progs/test_perf_branches.c | 74 +++++++
> 3 files changed, 280 insertions(+), 1 deletion(-)
> create mode 100644 tools/testing/selftests/bpf/prog_tests/perf_branches.c
> create mode 100644 tools/testing/selftests/bpf/progs/test_perf_branches.c
>
[...]
> + /* generate some branches on cpu 0 */
> + CPU_ZERO(&cpu_set);
> + CPU_SET(0, &cpu_set);
> + err = pthread_setaffinity_np(pthread_self(), sizeof(cpu_set), &cpu_set);
> + if (CHECK(err, "set_affinity", "cpu #0, err %d\n", err))
> + goto out_free_pb;
> + /* spin the loop for a while (random high number) */
> + for (i = 0; i < 1000000; ++i)
> + ++j;
> +
test_perf_branches__detach here?
> + /* read perf buffer */
> + err = perf_buffer__poll(pb, 500);
> + if (CHECK(err < 0, "perf_buffer__poll", "err %d\n", err))
> + goto out_free_pb;
> +
> + if (CHECK(!ok, "ok", "not ok\n"))
> + goto out_free_pb;
> +
[...]
> diff --git a/tools/testing/selftests/bpf/progs/test_perf_branches.c b/tools/testing/selftests/bpf/progs/test_perf_branches.c
> new file mode 100644
> index 000000000000..60327d512400
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_perf_branches.c
> @@ -0,0 +1,74 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (c) 2019 Facebook
> +
> +#include <stddef.h>
> +#include <linux/ptrace.h>
> +#include <linux/bpf.h>
> +#include <bpf/bpf_helpers.h>
> +#include "bpf_trace_helpers.h"
> +
> +struct fake_perf_branch_entry {
> + __u64 _a;
> + __u64 _b;
> + __u64 _c;
> +};
> +
> +struct output {
> + int required_size;
> + int written_stack;
> + int written_map;
> +};
> +
> +struct {
> + __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
> + __uint(key_size, sizeof(int));
> + __uint(value_size, sizeof(int));
> +} perf_buf_map SEC(".maps");
> +
> +typedef struct fake_perf_branch_entry fpbe_t[30];
> +
> +struct {
> + __uint(type, BPF_MAP_TYPE_ARRAY);
> + __uint(max_entries, 1);
> + __type(key, __u32);
> + __type(value, fpbe_t);
> +} scratch_map SEC(".maps");
Can you please use global variables instead of array and
perf_event_array? Would make BPF side clearer and userspace simpler.
struct output member will just become variables.
[...]
