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Date: Sat, 16 Jan 2021 18:11:50 -0800 From: Yonghong Song <yhs@...com> To: Qais Yousef <qais.yousef@....com>, <netdev@...r.kernel.org>, <bpf@...r.kernel.org> CC: Alexei Starovoitov <ast@...nel.org>, Andrii Nakryiko <andrii@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, Steven Rostedt <rostedt@...dmis.org>, "Peter Zijlstra (Intel)" <peterz@...radead.org>, <linux-kernel@...r.kernel.org> Subject: Re: [PATCH v2 bpf-next 2/2] selftests: bpf: Add a new test for bare tracepoints On 1/16/21 10:21 AM, Qais Yousef wrote: > Reuse module_attach infrastructure to add a new bare tracepoint to check > we can attach to it as a raw tracepoint. > > Signed-off-by: Qais Yousef <qais.yousef@....com> > --- > .../bpf/bpf_testmod/bpf_testmod-events.h | 6 +++++ > .../selftests/bpf/bpf_testmod/bpf_testmod.c | 21 ++++++++++++++- > .../selftests/bpf/bpf_testmod/bpf_testmod.h | 6 +++++ > .../selftests/bpf/prog_tests/module_attach.c | 27 +++++++++++++++++++ > .../selftests/bpf/progs/test_module_attach.c | 10 +++++++ > 5 files changed, 69 insertions(+), 1 deletion(-) > > diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h > index b83ea448bc79..89c6d58e5dd6 100644 > --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h > +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h > @@ -28,6 +28,12 @@ TRACE_EVENT(bpf_testmod_test_read, > __entry->pid, __entry->comm, __entry->off, __entry->len) > ); > > +/* A bare tracepoint with no event associated with it */ > +DECLARE_TRACE(bpf_testmod_test_write_bare, > + TP_PROTO(struct task_struct *task, struct bpf_testmod_test_write_ctx *ctx), > + TP_ARGS(task, ctx) > +); > + > #endif /* _BPF_TESTMOD_EVENTS_H */ > > #undef TRACE_INCLUDE_PATH > diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c > index 2df19d73ca49..e900adad2276 100644 > --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c > +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c > @@ -28,9 +28,28 @@ bpf_testmod_test_read(struct file *file, struct kobject *kobj, > EXPORT_SYMBOL(bpf_testmod_test_read); > ALLOW_ERROR_INJECTION(bpf_testmod_test_read, ERRNO); > > +noinline ssize_t > +bpf_testmod_test_write(struct file *file, struct kobject *kobj, > + struct bin_attribute *bin_attr, > + char *buf, loff_t off, size_t len) > +{ > + struct bpf_testmod_test_write_ctx ctx = { > + .buf = buf, > + .off = off, > + .len = len, > + }; > + > + trace_bpf_testmod_test_write_bare(current, &ctx); > + > + return -EIO; /* always fail */ > +} > +EXPORT_SYMBOL(bpf_testmod_test_write); > +ALLOW_ERROR_INJECTION(bpf_testmod_test_write, ERRNO); > + > static struct bin_attribute bin_attr_bpf_testmod_file __ro_after_init = { Do we need to remove __ro_after_init? > - .attr = { .name = "bpf_testmod", .mode = 0444, }, > + .attr = { .name = "bpf_testmod", .mode = 0666, }, > .read = bpf_testmod_test_read, > + .write = bpf_testmod_test_write, > }; > > static int bpf_testmod_init(void) > diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h > index b81adfedb4f6..b3892dc40111 100644 > --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h > +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h > @@ -11,4 +11,10 @@ struct bpf_testmod_test_read_ctx { > size_t len; > }; > > +struct bpf_testmod_test_write_ctx { > + char *buf; > + loff_t off; > + size_t len; > +}; > + > #endif /* _BPF_TESTMOD_H */ > diff --git a/tools/testing/selftests/bpf/prog_tests/module_attach.c b/tools/testing/selftests/bpf/prog_tests/module_attach.c > index 50796b651f72..e4605c0b5af1 100644 > --- a/tools/testing/selftests/bpf/prog_tests/module_attach.c > +++ b/tools/testing/selftests/bpf/prog_tests/module_attach.c > @@ -21,9 +21,34 @@ static int trigger_module_test_read(int read_sz) > return 0; > } > > +static int trigger_module_test_write(int write_sz) > +{ > + int fd, err; Init err = 0? > + char *buf = malloc(write_sz); > + > + if (!buf) > + return -ENOMEM; Looks like we already non-negative value, so return ENOMEM? > + > + memset(buf, 'a', write_sz); > + buf[write_sz-1] = '\0'; > + > + fd = open("/sys/kernel/bpf_testmod", O_WRONLY); > + err = -errno; > + if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", err)) > + goto out; Change the above to fd = open("/sys/kernel/bpf_testmod", O_WRONLY); if (CHECK(fd < 0, "testmod_file_open", "failed: %d\n", errno)) { err = -errno; goto out; } > + > + write(fd, buf, write_sz); > + close(fd); > +out: > + free(buf); > + No need for extra line here. > + return 0; return err. > +} > + > void test_module_attach(void) > { > const int READ_SZ = 456; > + const int WRITE_SZ = 457; > struct test_module_attach* skel; > struct test_module_attach__bss *bss; > int err; > @@ -48,8 +73,10 @@ void test_module_attach(void) > > /* trigger tracepoint */ > ASSERT_OK(trigger_module_test_read(READ_SZ), "trigger_read"); > + ASSERT_OK(trigger_module_test_write(WRITE_SZ), "trigger_write"); > > ASSERT_EQ(bss->raw_tp_read_sz, READ_SZ, "raw_tp"); > + ASSERT_EQ(bss->raw_tp_bare_write_sz, WRITE_SZ, "raw_tp_bare"); > ASSERT_EQ(bss->tp_btf_read_sz, READ_SZ, "tp_btf"); > ASSERT_EQ(bss->fentry_read_sz, READ_SZ, "fentry"); > ASSERT_EQ(bss->fentry_manual_read_sz, READ_SZ, "fentry_manual"); > diff --git a/tools/testing/selftests/bpf/progs/test_module_attach.c b/tools/testing/selftests/bpf/progs/test_module_attach.c > index efd1e287ac17..bd37ceec5587 100644 > --- a/tools/testing/selftests/bpf/progs/test_module_attach.c > +++ b/tools/testing/selftests/bpf/progs/test_module_attach.c > @@ -17,6 +17,16 @@ int BPF_PROG(handle_raw_tp, > return 0; > } > > +__u32 raw_tp_bare_write_sz = 0; > + > +SEC("raw_tp/bpf_testmod_test_write_bare") > +int BPF_PROG(handle_raw_tp_bare, > + struct task_struct *task, struct bpf_testmod_test_write_ctx *write_ctx) > +{ > + raw_tp_bare_write_sz = BPF_CORE_READ(write_ctx, len); > + return 0; > +} > + > __u32 tp_btf_read_sz = 0; > > SEC("tp_btf/bpf_testmod_test_read") >
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