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Date: Tue, 7 Dec 2021 14:54:33 -0800
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: Jiri Olsa <jolsa@...hat.com>
Cc: Andrii Nakryiko <andriin@...com>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
Martin KaFai Lau <kafai@...com>,
Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
John Fastabend <john.fastabend@...il.com>,
KP Singh <kpsingh@...omium.org>,
Andrii Nakryiko <andrii@...nel.org>
Subject: Re: [PATCH bpf-next 3/3] selftests/bpf: Add tests for
get_func_[arg|ret|arg_cnt] helpers
On Tue, Dec 7, 2021 at 10:14 AM Jiri Olsa <jolsa@...hat.com> wrote:
>
> On Mon, Dec 06, 2021 at 02:03:54PM -0800, Andrii Nakryiko wrote:
> >
> > On 12/4/21 6:07 AM, Jiri Olsa wrote:
> > > Adding tests for get_func_[arg|ret|arg_cnt] helpers.
> > > Using these helpers in fentry/fexit/fmod_ret programs.
> > >
> > > Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> > > ---
> > > .../bpf/prog_tests/get_func_args_test.c | 38 ++++++
> > > .../selftests/bpf/progs/get_func_args_test.c | 112 ++++++++++++++++++
> > > 2 files changed, 150 insertions(+)
> > > create mode 100644 tools/testing/selftests/bpf/prog_tests/get_func_args_test.c
> > > create mode 100644 tools/testing/selftests/bpf/progs/get_func_args_test.c
> > >
> > > diff --git a/tools/testing/selftests/bpf/prog_tests/get_func_args_test.c b/tools/testing/selftests/bpf/prog_tests/get_func_args_test.c
> > > new file mode 100644
> > > index 000000000000..c24807ae4361
> > > --- /dev/null
> > > +++ b/tools/testing/selftests/bpf/prog_tests/get_func_args_test.c
> > > @@ -0,0 +1,38 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +#include <test_progs.h>
> > > +#include "get_func_args_test.skel.h"
> > > +
> > > +void test_get_func_args_test(void)
> > > +{
> > > + struct get_func_args_test *skel = NULL;
> > > + __u32 duration = 0, retval;
> > > + int err, prog_fd;
> > > +
> > > + skel = get_func_args_test__open_and_load();
> > > + if (!ASSERT_OK_PTR(skel, "get_func_args_test__open_and_load"))
> > > + return;
> > > +
> > > + err = get_func_args_test__attach(skel);
> > > + if (!ASSERT_OK(err, "get_func_args_test__attach"))
> > > + goto cleanup;
> > > +
> > > + prog_fd = bpf_program__fd(skel->progs.test1);
> > > + err = bpf_prog_test_run(prog_fd, 1, NULL, 0,
> > > + NULL, NULL, &retval, &duration);
> > > + ASSERT_OK(err, "test_run");
> > > + ASSERT_EQ(retval, 0, "test_run");
> > > +
> > > + prog_fd = bpf_program__fd(skel->progs.fmod_ret_test);
> > > + err = bpf_prog_test_run(prog_fd, 1, NULL, 0,
> > > + NULL, NULL, &retval, &duration);
> > > + ASSERT_OK(err, "test_run");
> > > + ASSERT_EQ(retval, 1234, "test_run");
> >
> >
> > are the other two programs executed implicitly during one of those test
> > runs? Can you please leave a small comment somewhere here if that's true?
>
> test1 triggers all the bpf_fentry_test* fentry/fexits
> fmod_ret_test triggers the rest, I'll put it in comment
>
> >
> >
> > > +
> > > + ASSERT_EQ(skel->bss->test1_result, 1, "test1_result");
> > > + ASSERT_EQ(skel->bss->test2_result, 1, "test2_result");
> > > + ASSERT_EQ(skel->bss->test3_result, 1, "test3_result");
> > > + ASSERT_EQ(skel->bss->test4_result, 1, "test4_result");
> > > +
> > > +cleanup:
> > > + get_func_args_test__destroy(skel);
> > > +}
> > > diff --git a/tools/testing/selftests/bpf/progs/get_func_args_test.c b/tools/testing/selftests/bpf/progs/get_func_args_test.c
> > > new file mode 100644
> > > index 000000000000..0d0a67c849ae
> > > --- /dev/null
> > > +++ b/tools/testing/selftests/bpf/progs/get_func_args_test.c
> > > @@ -0,0 +1,112 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +#include <linux/bpf.h>
> > > +#include <bpf/bpf_helpers.h>
> > > +#include <bpf/bpf_tracing.h>
> > > +#include <errno.h>
> > > +
> > > +char _license[] SEC("license") = "GPL";
> > > +
> > > +__u64 test1_result = 0;
> > > +SEC("fentry/bpf_fentry_test1")
> > > +int BPF_PROG(test1)
> > > +{
> > > + __u64 cnt = bpf_get_func_arg_cnt(ctx);
> > > + __u64 a = 0, z = 0, ret = 0;
> > > + __s64 err;
> > > +
> > > + test1_result = cnt == 1;
> > > +
> > > + /* valid arguments */
> > > + err = bpf_get_func_arg(ctx, 0, &a);
> > > + test1_result &= err == 0 && (int) a == 1;
> >
> >
> > int cast unnecessary? but some ()'s wouldn't hurt...
>
> it is, 'a' is int and trampoline saves it with 32-bit register like:
>
> mov %edi,-0x8(%rbp)
>
> so the upper 4 bytes are not zeroed
oh, this is definitely worth a comment, it's quite a big gotcha we'll
need to remember
>
> >
> >
> > > +
> > > + /* not valid argument */
> > > + err = bpf_get_func_arg(ctx, 1, &z);
> > > + test1_result &= err == -EINVAL;
> > > +
> > > + /* return value fails in fentry */
> > > + err = bpf_get_func_ret(ctx, &ret);
> > > + test1_result &= err == -EINVAL;
> > > + return 0;
> > > +}
> > > +
> > > +__u64 test2_result = 0;
> > > +SEC("fexit/bpf_fentry_test2")
> > > +int BPF_PROG(test2)
> > > +{
> > > + __u64 cnt = bpf_get_func_arg_cnt(ctx);
> > > + __u64 a = 0, b = 0, z = 0, ret = 0;
> > > + __s64 err;
> > > +
> > > + test2_result = cnt == 2;
> > > +
> > > + /* valid arguments */
> > > + err = bpf_get_func_arg(ctx, 0, &a);
> > > + test2_result &= err == 0 && (int) a == 2;
> > > +
> > > + err = bpf_get_func_arg(ctx, 1, &b);
> > > + test2_result &= err == 0 && b == 3;
> > > +
> > > + /* not valid argument */
> > > + err = bpf_get_func_arg(ctx, 2, &z);
> > > + test2_result &= err == -EINVAL;
> > > +
> > > + /* return value */
> > > + err = bpf_get_func_ret(ctx, &ret);
> > > + test2_result &= err == 0 && ret == 5;
> > > + return 0;
> > > +}
> > > +
> > > +__u64 test3_result = 0;
> > > +SEC("fmod_ret/bpf_modify_return_test")
> > > +int BPF_PROG(fmod_ret_test, int _a, int *_b, int _ret)
> > > +{
> > > + __u64 cnt = bpf_get_func_arg_cnt(ctx);
> > > + __u64 a = 0, b = 0, z = 0, ret = 0;
> > > + __s64 err;
> > > +
> > > + test3_result = cnt == 2;
> > > +
> > > + /* valid arguments */
> > > + err = bpf_get_func_arg(ctx, 0, &a);
> > > + test3_result &= err == 0 && (int) a == 1;
> > > +
> > > + err = bpf_get_func_arg(ctx, 1, &b);
> > > + test3_result &= err == 0;
> >
> >
> > why no checking of b value here?
>
> right, ok
>
> >
> > > +
> > > + /* not valid argument */
> > > + err = bpf_get_func_arg(ctx, 2, &z);
> > > + test3_result &= err == -EINVAL;
> > > +
> > > + /* return value */
> > > + err = bpf_get_func_ret(ctx, &ret);
> > > + test3_result &= err == 0 && ret == 0;
> > > + return 1234;
> > > +}
> > > +
> > > +__u64 test4_result = 0;
> > > +SEC("fexit/bpf_modify_return_test")
> > > +int BPF_PROG(fexit_test, int _a, __u64 _b, int _ret)
> > > +{
> > > + __u64 cnt = bpf_get_func_arg_cnt(ctx);
> > > + __u64 a = 0, b = 0, z = 0, ret = 0;
> > > + __s64 err;
> > > +
> > > + test4_result = cnt == 2;
> > > +
> > > + /* valid arguments */
> > > + err = bpf_get_func_arg(ctx, 0, &a);
> > > + test4_result &= err == 0 && (int) a == 1;
> > > +
> > > + err = bpf_get_func_arg(ctx, 1, &b);
> > > + test4_result &= err == 0;
> >
> >
> > same, for consistency, b should have been checked, no?
>
> ok
>
> thanks,
> jirka
>
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