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Date:   Thu, 23 May 2019 05:50:30 +0000
From:   Yonghong Song <yhs@...com>
To:     Andrii Nakryiko <andrii.nakryiko@...il.com>
CC:     "bpf@...r.kernel.org" <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 5/22/19 8:47 PM, Andrii Nakryiko wrote:
> 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?
right. typo. will fix.
> 
>> +               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";
sure, will do this, to make line shorter.

> 
>> +       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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