From: Martynas Pumputis <m@lambda.lt>
To: Jiri Olsa <jolsa@kernel.org>, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>
Cc: 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>,
Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>,
"Masami Hiramatsu (Google)" <mhiramat@kernel.org>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCHv4 bpf-next 5/6] bpf: Return value in kprobe get_func_ip only for entry address
Date: Sun, 25 Sep 2022 07:42:48 +0200 [thread overview]
Message-ID: <0e1742f8-06ea-1c69-d245-e3202a751f42@lambda.lt> (raw)
In-Reply-To: <20220922210320.1076658-6-jolsa@kernel.org>
On 9/22/22 23:03, Jiri Olsa wrote:
> Changing return value of kprobe's version of bpf_get_func_ip
> to return zero if the attach address is not on the function's
> entry point.
>
> For kprobes attached in the middle of the function we can't easily
> get to the function address especially now with the CONFIG_X86_KERNEL_IBT
> support.
>
> If user cares about current IP for kprobes attached within the
> function body, they can get it with PT_REGS_IP(ctx).
>
> Suggested-by: Andrii Nakryiko <andrii@kernel.org>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested the patches with "pwru --filter-func='.*skb.*'
--filter-dst-ip=1.1.1.1" from [1] - the symbol name resolution works,
thanks!
Without your patches:
SKB CPU PROCESS FUNC
0xffff8989c159b4e8 0 [curl] 0xffffffffbbb06164
0xffff8989c223f000 0 [curl] 0xffffffffbbb07534
0xffff8989c223f000 0 [curl] 0xffffffffbbb04934
0xffff8989c223f000 0 [curl] skb_release_data
0xffff8989c223f000 0 [curl] kfree_skbmem
0xffff8989c159b4e8 0 [curl] 0xffffffffbbb00db4
[..]
With patches:
SKB CPU PROCESS FUNC
0xffffa4564159b4e8 0 [curl] validate_xmit_skb_list
0xffffa4564159b4e8 0 [curl] netif_skb_features
0xffffa4564159b4e8 0 [curl] skb_network_protocol
0xffffa4564159b4e8 0 [curl] skb_csum_hwoffload_help
0xffffa4564159b4e8 0 [curl] skb_checksum_help
0xffffa4564159b4e8 0 [curl] skb_ensure_writable
0xffffa4564159b4e8 0 [curl] skb_to_sgvec
[..]
[1]: https://github.com/cilium/pwru/tree/test-ibt-kernel-fix
Acked-by: Martynas Pumputis <m@lambda.lt>
> ---
> kernel/trace/bpf_trace.c | 5 ++++-
> tools/testing/selftests/bpf/progs/get_func_ip_test.c | 4 ++--
> 2 files changed, 6 insertions(+), 3 deletions(-)
[..]
next prev parent reply other threads:[~2022-09-25 5:43 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-22 21:03 [PATCHv4 bpf-next 0/6] bpf: Fixes for CONFIG_X86_KERNEL_IBT Jiri Olsa
2022-09-22 21:03 ` [PATCHv4 bpf-next 1/6] kprobes: Add new KPROBE_FLAG_ON_FUNC_ENTRY kprobe flag Jiri Olsa
2022-09-22 21:03 ` [PATCHv4 bpf-next 2/6] ftrace: Keep the resolved addr in kallsyms_callback Jiri Olsa
2022-09-22 21:03 ` [PATCHv4 bpf-next 3/6] bpf: Use given function address for trampoline ip arg Jiri Olsa
2022-09-22 21:03 ` [PATCHv4 bpf-next 4/6] bpf: Adjust kprobe_multi entry_ip for CONFIG_X86_KERNEL_IBT Jiri Olsa
2022-09-23 21:40 ` Andrii Nakryiko
2022-09-22 21:03 ` [PATCHv4 bpf-next 5/6] bpf: Return value in kprobe get_func_ip only for entry address Jiri Olsa
2022-09-23 21:42 ` Andrii Nakryiko
2022-09-26 13:58 ` Jiri Olsa
2022-09-25 5:42 ` Martynas Pumputis [this message]
2022-09-26 13:58 ` Jiri Olsa
2022-09-22 21:03 ` [PATCHv4 bpf-next 6/6] selftests/bpf: Fix get_func_ip offset test for CONFIG_X86_KERNEL_IBT Jiri Olsa
2022-09-23 21:43 ` Andrii Nakryiko
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