From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Jiri Olsa <jolsa@kernel.org>
Cc: "Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Andrii Nakryiko" <andriin@fb.com>,
Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
"Martin KaFai Lau" <kafai@fb.com>,
"Song Liu" <songliubraving@fb.com>, "Yonghong Song" <yhs@fb.com>,
"John Fastabend" <john.fastabend@gmail.com>,
"KP Singh" <kpsingh@chromium.org>,
"Toke Høiland-Jørgensen" <toke@redhat.com>,
"Yauheni Kaliuta" <ykaliuta@redhat.com>
Subject: Re: [PATCH bpf-next] selftests/bpf: Fix test_attach_probe for powerpc uprobes
Date: Mon, 1 Mar 2021 16:34:24 -0800 [thread overview]
Message-ID: <CAEf4BzbBnR3M60HepC_CFDsdMQDBYoEWiWtREUaLxrrxyBce0Q@mail.gmail.com> (raw)
In-Reply-To: <20210301190416.90694-1-jolsa@kernel.org>
On Mon, Mar 1, 2021 at 11:11 AM Jiri Olsa <jolsa@kernel.org> wrote:
>
> When testing uprobes we the test gets GEP (Global Entry Point)
> address from kallsyms, but then the function is called locally
> so the uprobe is not triggered.
>
> Fixing this by adjusting the address to LEP (Local Entry Point)
> for powerpc arch.
>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
> .../selftests/bpf/prog_tests/attach_probe.c | 18 +++++++++++++++++-
> 1 file changed, 17 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/attach_probe.c b/tools/testing/selftests/bpf/prog_tests/attach_probe.c
> index a0ee87c8e1ea..c3cfb48d3ed0 100644
> --- a/tools/testing/selftests/bpf/prog_tests/attach_probe.c
> +++ b/tools/testing/selftests/bpf/prog_tests/attach_probe.c
> @@ -2,6 +2,22 @@
> #include <test_progs.h>
> #include "test_attach_probe.skel.h"
>
> +#if defined(__powerpc64__)
> +/*
> + * We get the GEP (Global Entry Point) address from kallsyms,
> + * but then the function is called locally, so we need to adjust
> + * the address to get LEP (Local Entry Point).
> + */
> +#define LEP_OFFSET 8
> +
> +static ssize_t get_offset(ssize_t offset)
if we mark this function __weak global, would it work as is? Would it
get an address of a global entry point? I know nothing about this GEP
vs LEP stuff, interesting :)
> +{
> + return offset + LEP_OFFSET;
> +}
> +#else
> +#define get_offset(offset) (offset)
> +#endif
> +
> ssize_t get_base_addr() {
> size_t start, offset;
> char buf[256];
> @@ -36,7 +52,7 @@ void test_attach_probe(void)
> if (CHECK(base_addr < 0, "get_base_addr",
> "failed to find base addr: %zd", base_addr))
> return;
> - uprobe_offset = (size_t)&get_base_addr - base_addr;
> + uprobe_offset = get_offset((size_t)&get_base_addr - base_addr);
>
> skel = test_attach_probe__open_and_load();
> if (CHECK(!skel, "skel_open", "failed to open skeleton\n"))
> --
> 2.29.2
>
next prev parent reply other threads:[~2021-03-02 10:38 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-01 19:04 [PATCH bpf-next] selftests/bpf: Fix test_attach_probe for powerpc uprobes Jiri Olsa
2021-03-01 22:58 ` Yonghong Song
2021-03-02 10:35 ` Jiri Olsa
2021-03-03 6:40 ` Naveen N. Rao
2021-03-03 22:49 ` Jiri Olsa
2021-03-04 0:46 ` Michael Ellerman
2021-03-04 15:55 ` Jiri Olsa
2021-03-04 1:34 ` Naveen N. Rao
2021-03-05 13:38 ` Jiri Olsa
2021-03-02 0:34 ` Andrii Nakryiko [this message]
2021-03-02 11:14 ` Jiri Olsa
2021-03-02 17:19 ` Yonghong Song
2021-03-03 6:42 ` Naveen N. Rao
2021-03-02 18:31 ` Andrii Nakryiko
2021-03-02 18:58 ` Jiri Olsa
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