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Subject[PATCH v2 bpf-next 2/2] selftests: bpf: Add a new test for bare tracepoints
Date
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@arm.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 = {
- .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;
+ char *buf = malloc(write_sz);
+
+ if (!buf)
+ 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;
+
+ write(fd, buf, write_sz);
+ close(fd);
+out:
+ free(buf);
+
+ return 0;
+}
+
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")
--
2.25.1
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