Re: [PATCHv3 bpf-next 6/7] selftests/bpf: Add uretprobe compat test

[Andrii Nakryiko <andrii.nakryiko@gmail.com>]

On Sun, Apr 21, 2024 at 12:43 PM Jiri Olsa <jolsa@kernel.org> wrote:
>
> Adding test that adds return uprobe inside 32 bit task
> and verify the return uprobe and attached bpf programs
> get properly executed.
>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
>  tools/testing/selftests/bpf/.gitignore        |  1 +
>  tools/testing/selftests/bpf/Makefile          |  6 ++-
>  .../selftests/bpf/prog_tests/uprobe_syscall.c | 40 +++++++++++++++++++
>  .../bpf/progs/uprobe_syscall_compat.c         | 13 ++++++
>  4 files changed, 59 insertions(+), 1 deletion(-)
>  create mode 100644 tools/testing/selftests/bpf/progs/uprobe_syscall_compat.c
>
> diff --git a/tools/testing/selftests/bpf/.gitignore b/tools/testing/selftests/bpf/.gitignore
> index f1aebabfb017..69d71223c0dd 100644
> --- a/tools/testing/selftests/bpf/.gitignore
> +++ b/tools/testing/selftests/bpf/.gitignore
> @@ -45,6 +45,7 @@ test_cpp
>  /veristat
>  /sign-file
>  /uprobe_multi
> +/uprobe_compat
>  *.ko
>  *.tmp
>  xskxceiver
> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> index edc73f8f5aef..d170b63eca62 100644
> --- a/tools/testing/selftests/bpf/Makefile
> +++ b/tools/testing/selftests/bpf/Makefile
> @@ -134,7 +134,7 @@ TEST_GEN_PROGS_EXTENDED = test_sock_addr test_skb_cgroup_id_user \
>         xskxceiver xdp_redirect_multi xdp_synproxy veristat xdp_hw_metadata \
>         xdp_features bpf_test_no_cfi.ko
>
> -TEST_GEN_FILES += liburandom_read.so urandom_read sign-file uprobe_multi
> +TEST_GEN_FILES += liburandom_read.so urandom_read sign-file uprobe_multi uprobe_compat

you need to add uprobe_compat to TRUNNER_EXTRA_FILES as well, no?

>
>  # Emit succinct information message describing current building step
>  # $1 - generic step name (e.g., CC, LINK, etc);
> @@ -761,6 +761,10 @@ $(OUTPUT)/uprobe_multi: uprobe_multi.c
>         $(call msg,BINARY,,$@)
>         $(Q)$(CC) $(CFLAGS) -O0 $(LDFLAGS) $^ $(LDLIBS) -o $@
>
> +$(OUTPUT)/uprobe_compat:
> +       $(call msg,BINARY,,$@)
> +       $(Q)echo "int main() { return 0; }" | $(CC) $(CFLAGS) -xc -m32 -O0 - -o $@
> +
>  EXTRA_CLEAN := $(SCRATCH_DIR) $(HOST_SCRATCH_DIR)                      \
>         prog_tests/tests.h map_tests/tests.h verifier/tests.h           \
>         feature bpftool                                                 \
> diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c b/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
> index 9233210a4c33..3770254d893b 100644
> --- a/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
> +++ b/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
> @@ -11,6 +11,7 @@
>  #include <sys/wait.h>
>  #include "uprobe_syscall.skel.h"
>  #include "uprobe_syscall_call.skel.h"
> +#include "uprobe_syscall_compat.skel.h"
>
>  __naked unsigned long uretprobe_regs_trigger(void)
>  {
> @@ -291,6 +292,35 @@ static void test_uretprobe_syscall_call(void)
>                  "read_trace_pipe_iter");
>         ASSERT_EQ(found, 0, "found");
>  }
> +
> +static void trace_pipe_compat_cb(const char *str, void *data)
> +{
> +       if (strstr(str, "uretprobe compat") != NULL)
> +               (*(int *)data)++;
> +}
> +
> +static void test_uretprobe_compat(void)
> +{
> +       struct uprobe_syscall_compat *skel = NULL;
> +       int err, found = 0;
> +
> +       skel = uprobe_syscall_compat__open_and_load();
> +       if (!ASSERT_OK_PTR(skel, "uprobe_syscall_compat__open_and_load"))
> +               goto cleanup;
> +
> +       err = uprobe_syscall_compat__attach(skel);
> +       if (!ASSERT_OK(err, "uprobe_syscall_compat__attach"))
> +               goto cleanup;
> +
> +       system("./uprobe_compat");
> +
> +       ASSERT_OK(read_trace_pipe_iter(trace_pipe_compat_cb, &found, 1000),
> +                "read_trace_pipe_iter");

why so complicated? can't you just set global variable that it was called

> +       ASSERT_EQ(found, 1, "found");
> +
> +cleanup:
> +       uprobe_syscall_compat__destroy(skel);
> +}
>  #else
>  static void test_uretprobe_regs_equal(void)
>  {
> @@ -306,6 +336,11 @@ static void test_uretprobe_syscall_call(void)
>  {
>         test__skip();
>  }
> +
> +static void test_uretprobe_compat(void)
> +{
> +       test__skip();
> +}
>  #endif
>
>  void test_uprobe_syscall(void)
> @@ -320,3 +355,8 @@ void serial_test_uprobe_syscall_call(void)
>  {
>         test_uretprobe_syscall_call();
>  }
> +
> +void serial_test_uprobe_syscall_compat(void)

and then no need for serial_test?

> +{
> +       test_uretprobe_compat();
> +}
> diff --git a/tools/testing/selftests/bpf/progs/uprobe_syscall_compat.c b/tools/testing/selftests/bpf/progs/uprobe_syscall_compat.c
> new file mode 100644
> index 000000000000..f8adde7f08e2
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/uprobe_syscall_compat.c
> @@ -0,0 +1,13 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <linux/bpf.h>
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_tracing.h>
> +
> +char _license[] SEC("license") = "GPL";
> +
> +SEC("uretprobe.multi/./uprobe_compat:main")
> +int uretprobe_compat(struct pt_regs *ctx)
> +{
> +       bpf_printk("uretprobe compat\n");
> +       return 0;
> +}
> --
> 2.44.0
>