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selftests: bpf: Add a new test for bare tracepoints
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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>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210119122237.2426878-3-qais.yousef@arm.com
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Qais Yousef authored and Alexei Starovoitov committed Jan 20, 2021
1 parent 6939f4e commit 407be92
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Showing 5 changed files with 69 additions and 1 deletion.
6 changes: 6 additions & 0 deletions tools/testing/selftests/bpf/bpf_testmod/bpf_testmod-events.h
Original file line number Diff line number Diff line change
Expand Up @@ -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
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21 changes: 20 additions & 1 deletion tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
Original file line number Diff line number Diff line change
Expand Up @@ -31,9 +31,28 @@ 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)
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6 changes: 6 additions & 0 deletions tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
Original file line number Diff line number Diff line change
Expand Up @@ -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 */
27 changes: 27 additions & 0 deletions tools/testing/selftests/bpf/prog_tests/module_attach.c
Original file line number Diff line number Diff line change
Expand Up @@ -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)) {
free(buf);
return err;
}

write(fd, buf, write_sz);
close(fd);
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;
Expand All @@ -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");
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10 changes: 10 additions & 0 deletions tools/testing/selftests/bpf/progs/test_module_attach.c
Original file line number Diff line number Diff line change
Expand Up @@ -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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