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Date: Wed, 22 May 2019 20:47:59 -0700
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: Yonghong Song <yhs@...com>
Cc: bpf@...r.kernel.org, Networking <netdev@...r.kernel.org>,
Alexei Starovoitov <ast@...com>,
Daniel Borkmann <daniel@...earbox.net>,
Kernel Team <kernel-team@...com>,
Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH bpf-next v3 3/3] tools/bpf: add selftest in test_progs for
bpf_send_signal() helper
On Wed, May 22, 2019 at 4:16 PM Yonghong Song <yhs@...com> wrote:
>
> The test covered both nmi and tracepoint perf events.
> $ ./test_progs
> ...
> test_send_signal_tracepoint:PASS:tracepoint 0 nsec
> ...
> test_send_signal_common:PASS:tracepoint 0 nsec
> ...
> test_send_signal_common:PASS:perf_event 0 nsec
> ...
> test_send_signal:OK
>
> Signed-off-by: Yonghong Song <yhs@...com>
> ---
Looks good to me, just minor nits below.
Acked-by: Andrii Nakryiko <andriin@...com>
> tools/testing/selftests/bpf/bpf_helpers.h | 1 +
> .../selftests/bpf/prog_tests/send_signal.c | 193 ++++++++++++++++++
> .../bpf/progs/test_send_signal_kern.c | 51 +++++
> 3 files changed, 245 insertions(+)
> create mode 100644 tools/testing/selftests/bpf/prog_tests/send_signal.c
> create mode 100644 tools/testing/selftests/bpf/progs/test_send_signal_kern.c
>
> diff --git a/tools/testing/selftests/bpf/bpf_helpers.h b/tools/testing/selftests/bpf/bpf_helpers.h
> index 5f6f9e7aba2a..cb02521b8e58 100644
> --- a/tools/testing/selftests/bpf/bpf_helpers.h
> +++ b/tools/testing/selftests/bpf/bpf_helpers.h
> @@ -216,6 +216,7 @@ static void *(*bpf_sk_storage_get)(void *map, struct bpf_sock *sk,
> (void *) BPF_FUNC_sk_storage_get;
> static int (*bpf_sk_storage_delete)(void *map, struct bpf_sock *sk) =
> (void *)BPF_FUNC_sk_storage_delete;
> +static int (*bpf_send_signal)(unsigned sig) = (void *)BPF_FUNC_send_signal;
>
> /* llvm builtin functions that eBPF C program may use to
> * emit BPF_LD_ABS and BPF_LD_IND instructions
> diff --git a/tools/testing/selftests/bpf/prog_tests/send_signal.c b/tools/testing/selftests/bpf/prog_tests/send_signal.c
> new file mode 100644
> index 000000000000..ff2cabd3d8c4
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/send_signal.c
> @@ -0,0 +1,193 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <test_progs.h>
> +
> +static volatile int sigusr1_received = 0;
> +
> +static void sigusr1_handler(int signum)
> +{
> + sigusr1_received++;
> +}
> +
> +static int test_send_signal_common(struct perf_event_attr *attr,
> + int prog_type,
> + const char *test_name)
> +{
> + int err = -1, pmu_fd, prog_fd, info_map_fd, status_map_fd;
> + const char *file = "./test_send_signal_kern.o";
> + struct bpf_object *obj = NULL;
> + int pipe_c2p[2], pipe_p2c[2];
> + __u32 key = 0, duration = 0;
> + char buf[256];
> + pid_t pid;
> + __u64 val;
> +
> + if (CHECK(pipe(pipe_c2p), test_name,
> + "pipe pipe_c2p error: %s\n", strerror(errno)))
> + goto no_fork_done;
> +
> + if (CHECK(pipe(pipe_p2c), test_name,
> + "pipe pipe_p2c error: %s\n", strerror(errno))) {
> + close(pipe_c2p[0]);
> + close(pipe_c2p[1]);
> + goto no_fork_done;
> + }
> +
> + pid = fork();
> + if (CHECK(pid < 0, test_name, "fork error: %s\n", strerror(errno))) {
> + close(pipe_c2p[0]);
> + close(pipe_c2p[1]);
> + close(pipe_p2c[0]);
> + close(pipe_p2c[1]);
> + goto no_fork_done;
> + }
> +
> + if (pid == 0) {
> + /* install signal handler and notify parent */
> + signal(SIGUSR1, sigusr1_handler);
> +
> + close(pipe_c2p[0]); /* close read */
> + close(pipe_p2c[1]); /* close write */
> +
> + /* notify parent signal handler is installed */
> + write(pipe_c2p[1], buf, 1);
> +
> + /* make sense parent enabled bpf program to send_signal */
typo? sense => sure?
> + read(pipe_p2c[0], buf, 1);
> +
> + /* wait a little for signal handler */
> + sleep(1);
> +
> + if (sigusr1_received)
> + write(pipe_c2p[1], "2", 1);
> + else
> + write(pipe_c2p[1], "0", 1);
> +
> + /* wait for parent notification and exit */
> + read(pipe_p2c[0], buf, 1);
> +
> + close(pipe_c2p[1]);
> + close(pipe_p2c[0]);
> + exit(0);
> + }
> +
> + close(pipe_c2p[1]); /* close write */
> + close(pipe_p2c[0]); /* close read */
> +
> + err = bpf_prog_load(file, prog_type, &obj, &prog_fd);
> + if (CHECK(err < 0, test_name, "bpf_prog_load error: %s\n",
> + strerror(errno)))
> + goto prog_load_failure;
> +
> + pmu_fd = syscall(__NR_perf_event_open, attr, pid, -1,
> + -1 /* group id */, 0 /* flags */);
> + if (CHECK(pmu_fd < 0, test_name, "perf_event_open error: %s\n",
> + strerror(errno))) {
> + err = -1;
> + goto close_prog;
> + }
> +
> + err = ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0);
> + if (CHECK(err < 0, test_name, "ioctl perf_event_ioc_enable error: %s\n",
> + strerror(errno)))
> + goto disable_pmu;
> +
> + err = ioctl(pmu_fd, PERF_EVENT_IOC_SET_BPF, prog_fd);
> + if (CHECK(err < 0, test_name, "ioctl perf_event_ioc_set_bpf error: %s\n",
> + strerror(errno)))
> + goto disable_pmu;
> +
> + err = -1;
> + info_map_fd = bpf_object__find_map_fd_by_name(obj, "info_map");
> + if (CHECK(info_map_fd < 0, test_name, "find map %s error\n", "info_map"))
> + goto disable_pmu;
> +
> + status_map_fd = bpf_object__find_map_fd_by_name(obj, "status_map");
> + if (CHECK(status_map_fd < 0, test_name, "find map %s error\n", "status_map"))
> + goto disable_pmu;
> +
> + /* wait until child signal handler installed */
> + read(pipe_c2p[0], buf, 1);
> +
> + /* trigger the bpf send_signal */
> + key = 0;
> + val = (((__u64)(SIGUSR1)) << 32) | pid;
> + bpf_map_update_elem(info_map_fd, &key, &val, 0);
> +
> + /* notify child that bpf program can send_signal now */
> + write(pipe_p2c[1], buf, 1);
> +
> + /* wait for result */
> + read(pipe_c2p[0], buf, 1);
> +
> + err = CHECK(buf[0] != '2', test_name, "incorrect result\n");
> +
> + /* notify child safe to exit */
> + write(pipe_p2c[1], buf, 1);
> +
> +disable_pmu:
> + close(pmu_fd);
> +close_prog:
> + bpf_object__close(obj);
> +prog_load_failure:
> + close(pipe_c2p[0]);
> + close(pipe_p2c[1]);
> + wait(NULL);
> +no_fork_done:
> + return err;
> +}
> +
> +static int test_send_signal_tracepoint(void)
> +{
> + struct perf_event_attr attr = {
> + .type = PERF_TYPE_TRACEPOINT,
> + .sample_type = PERF_SAMPLE_RAW | PERF_SAMPLE_CALLCHAIN,
> + .sample_period = 1,
> + .wakeup_events = 1,
> + };
> + __u32 duration = 0;
> + int bytes, efd;
> + char buf[256];
> +
> + snprintf(buf, sizeof(buf),
> + "/sys/kernel/debug/tracing/events/syscalls/sys_enter_nanosleep/id");
You could do it statically:
char buf[256] = "/sys/...../id";
> + efd = open(buf, O_RDONLY, 0);
> + if (CHECK(efd < 0, "tracepoint",
> + "open syscalls/sys_enter_nanosleep/id failure: %s\n",
> + strerror(errno)))
> + return -1;
> +
> + bytes = read(efd, buf, sizeof(buf));
> + close(efd);
> + if (CHECK(bytes <= 0 || bytes >= sizeof(buf), "tracepoint",
> + "read syscalls/sys_enter_nanosleep/id failure: %s\n",
> + strerror(errno)))
> + return -1;
> +
> + attr.config = strtol(buf, NULL, 0);
> +
> + return test_send_signal_common(&attr, BPF_PROG_TYPE_TRACEPOINT, "tracepoint");
> +}
> +
> +static int test_send_signal_nmi(void)
> +{
> + struct perf_event_attr attr = {
> + .sample_freq = 50,
> + .freq = 1,
> + .type = PERF_TYPE_HARDWARE,
> + .config = PERF_COUNT_HW_CPU_CYCLES,
> + };
> +
> + return test_send_signal_common(&attr, BPF_PROG_TYPE_PERF_EVENT, "perf_event");
> +}
> +
> +void test_send_signal(void)
> +{
> + int ret = 0;
> +
> + ret |= test_send_signal_tracepoint();
> + ret |= test_send_signal_nmi();
> + if (!ret)
> + printf("test_send_signal:OK\n");
> + else
> + printf("test_send_signal:FAIL\n");
> +}
> diff --git a/tools/testing/selftests/bpf/progs/test_send_signal_kern.c b/tools/testing/selftests/bpf/progs/test_send_signal_kern.c
> new file mode 100644
> index 000000000000..45a1a1a2c345
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_send_signal_kern.c
> @@ -0,0 +1,51 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (c) 2019 Facebook
> +#include <linux/bpf.h>
> +#include <linux/version.h>
> +#include "bpf_helpers.h"
> +
> +struct bpf_map_def SEC("maps") info_map = {
> + .type = BPF_MAP_TYPE_ARRAY,
> + .key_size = sizeof(__u32),
> + .value_size = sizeof(__u64),
> + .max_entries = 1,
> +};
> +
> +BPF_ANNOTATE_KV_PAIR(info_map, __u32, __u64);
> +
> +struct bpf_map_def SEC("maps") status_map = {
> + .type = BPF_MAP_TYPE_ARRAY,
> + .key_size = sizeof(__u32),
> + .value_size = sizeof(__u64),
> + .max_entries = 1,
> +};
> +
> +BPF_ANNOTATE_KV_PAIR(status_map, __u32, __u64);
> +
> +SEC("send_signal_demo")
> +int bpf_send_signal_test(void *ctx)
> +{
> + __u64 *info_val, *status_val;
> + __u32 key = 0, pid, sig;
> + int ret;
> +
> + status_val = bpf_map_lookup_elem(&status_map, &key);
> + if (!status_val || *status_val != 0)
> + return 0;
> +
> + info_val = bpf_map_lookup_elem(&info_map, &key);
> + if (!info_val || *info_val == 0)
> + return 0;
> +
> + sig = *info_val >> 32;
> + pid = *info_val & 0xffffFFFF;
> +
> + if ((bpf_get_current_pid_tgid() >> 32) == pid) {
> + ret = bpf_send_signal(sig);
> + if (ret == 0)
> + *status_val = 1;
> + }
> +
> + return 0;
> +}
> +char __license[] SEC("license") = "GPL";
> --
> 2.17.1
>
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