From: Eduard Zingerman <eddyz87@gmail.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: "Jose E. Marchesi" <jose.marchesi@oracle.com>,
"Jose E. Marchesi" <jemarch@gnu.org>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
Yonghong Song <yonghong.song@linux.dev>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@kernel.org>,
Daniel Xu <dxu@dxuuu.xyz>,
John Fastabend <john.fastabend@gmail.com>,
bpf <bpf@vger.kernel.org>, Kernel Team <kernel-team@fb.com>
Subject: Re: asm register constraint. Was: [PATCH v2 bpf-next 2/5] bpf: Introduce "volatile compare" macro
Date: Wed, 17 Jan 2024 01:15:00 +0200 [thread overview]
Message-ID: <5b1caa7f70400e897bafcff489fb9c461f62db98.camel@gmail.com> (raw)
In-Reply-To: <CAADnVQ+57cJ_ChW10jAwvxV03Tctx1ytMPParVocSYYxGuY5PQ@mail.gmail.com>
On Tue, 2024-01-16 at 10:40 -0800, Alexei Starovoitov wrote:
[...]
> The changes to all three make sense, but they might cause regressions
> if they are not synchronized with new llvm.
> cilium/tetragon can control the llvm version to some degree, but not selftests.
> Should we add clang macro like __BPF_CPU_VERSION__ and ifdef
> different asm style depending on that?
> I suspect this "(short)" workaround will still be needed for quite
> some time while people upgrade to the latest llvm.
> something like __BPF_STRICT_ASM_CONSTRAINT__ ?
> Maybe a flag too that can revert to old behavior without warnings?
After my changes selftests are passing both with old and new
constraint semantics, so such macro definitions / compiler flags
are not necessary for selftests.
(Although, I have not yet checked the codegen difference,
so the absence of the "(short)" thing might be visible there).
As for Cilium / Tetragon: I checked verification of the object files
with both LLVM versions, but adding compiler flag might make sense.
Maybe compiler users should comment?
next prev parent reply other threads:[~2024-01-16 23:15 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-21 3:38 [PATCH v2 bpf-next 0/5] bpf: volatile compare Alexei Starovoitov
2023-12-21 3:38 ` [PATCH v2 bpf-next 1/5] selftests/bpf: Attempt to build BPF programs with -Wsign-compare Alexei Starovoitov
2023-12-21 3:38 ` [PATCH v2 bpf-next 2/5] bpf: Introduce "volatile compare" macro Alexei Starovoitov
2023-12-21 4:27 ` Kumar Kartikeya Dwivedi
2023-12-22 22:59 ` Alexei Starovoitov
2023-12-25 20:33 ` Alexei Starovoitov
2024-01-04 20:06 ` Eduard Zingerman
2024-01-04 21:02 ` Alexei Starovoitov
2024-01-05 21:47 ` Eduard Zingerman
2024-01-08 21:21 ` Yonghong Song
2024-01-08 23:16 ` Eduard Zingerman
2024-01-08 21:33 ` asm register constraint. Was: " Alexei Starovoitov
2024-01-08 23:22 ` Yonghong Song
2024-01-09 10:49 ` Jose E. Marchesi
2024-01-09 12:09 ` Jose E. Marchesi
2024-01-11 18:33 ` Jose E. Marchesi
2024-01-15 16:33 ` Eduard Zingerman
2024-01-16 17:47 ` Alexei Starovoitov
2024-01-16 19:07 ` Yonghong Song
2024-01-16 19:34 ` Alexei Starovoitov
2024-01-16 23:14 ` Yonghong Song
2024-01-17 22:43 ` Alexei Starovoitov
2024-01-16 23:55 ` Eduard Zingerman
2024-01-16 18:40 ` Alexei Starovoitov
2024-01-16 23:15 ` Eduard Zingerman [this message]
2024-01-11 2:46 ` Alexei Starovoitov
2024-01-11 10:34 ` Jose E. Marchesi
2024-01-11 16:46 ` Eduard Zingerman
2023-12-21 3:38 ` [PATCH v2 bpf-next 3/5] selftests/bpf: Convert exceptions_assert.c to bpf_cmp Alexei Starovoitov
2023-12-21 3:38 ` [PATCH v2 bpf-next 4/5] selftests/bpf: Remove bpf_assert_eq-like macros Alexei Starovoitov
2023-12-21 3:38 ` [RFC PATCH v2 bpf-next 5/5] selftests/bpf: Attempt to convert profiler.c to bpf_cmp Alexei Starovoitov
2023-12-21 18:01 ` [PATCH v2 bpf-next 0/5] bpf: volatile compare Jiri Olsa
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