BPF Archive on lore.kernel.org
 help / color / Atom feed
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
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
>

  parent reply index

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-01 19:04 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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=CAEf4BzbBnR3M60HepC_CFDsdMQDBYoEWiWtREUaLxrrxyBce0Q@mail.gmail.com \
    --to=andrii.nakryiko@gmail.com \
    --cc=andriin@fb.com \
    --cc=ast@kernel.org \
    --cc=bpf@vger.kernel.org \
    --cc=daniel@iogearbox.net \
    --cc=john.fastabend@gmail.com \
    --cc=jolsa@kernel.org \
    --cc=kafai@fb.com \
    --cc=kpsingh@chromium.org \
    --cc=netdev@vger.kernel.org \
    --cc=songliubraving@fb.com \
    --cc=toke@redhat.com \
    --cc=yhs@fb.com \
    --cc=ykaliuta@redhat.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

BPF Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/bpf/0 bpf/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 bpf bpf/ https://lore.kernel.org/bpf \
		bpf@vger.kernel.org
	public-inbox-index bpf

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.bpf


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git