From: Will Deacon <will@kernel.org>
To: Daniel Borkmann <daniel@iogearbox.net>
Cc: Hou Tao <houtao1@huawei.com>, Alexei Starovoitov <ast@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Martin KaFai Lau <kafai@fb.com>, Yonghong Song <yhs@fb.com>,
Andrii Nakryiko <andrii@kernel.org>,
Song Liu <songliubraving@fb.com>,
"David S . Miller" <davem@davemloft.net>,
John Fastabend <john.fastabend@gmail.com>,
netdev@vger.kernel.org, bpf@vger.kernel.org,
Zi Shen Lim <zlim.lnx@gmail.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Julien Thierry <jthierry@redhat.com>,
Ard Biesheuvel <ardb@kernel.org>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH bpf-next v3 2/4] arm64: insn: add encoders for atomic operations
Date: Wed, 16 Feb 2022 17:16:02 +0000 [thread overview]
Message-ID: <20220216171602.GA10877@willie-the-truck> (raw)
In-Reply-To: <4524da71-3977-07db-bd6e-cebd1c539805@iogearbox.net>
On Fri, Feb 11, 2022 at 03:39:48PM +0100, Daniel Borkmann wrote:
> On 1/29/22 11:04 PM, Hou Tao wrote:
> > It is a preparation patch for eBPF atomic supports under arm64. eBPF
> > needs support atomic[64]_fetch_add, atomic[64]_[fetch_]{and,or,xor} and
> > atomic[64]_{xchg|cmpxchg}. The ordering semantics of eBPF atomics are
> > the same with the implementations in linux kernel.
> >
> > Add three helpers to support LDCLR/LDEOR/LDSET/SWP, CAS and DMB
> > instructions. STADD/STCLR/STEOR/STSET are simply encoded as aliases for
> > LDADD/LDCLR/LDEOR/LDSET with XZR as the destination register, so no extra
> > helper is added. atomic_fetch_add() and other atomic ops needs support for
> > STLXR instruction, so extend enum aarch64_insn_ldst_type to do that.
> >
> > LDADD/LDEOR/LDSET/SWP and CAS instructions are only available when LSE
> > atomics is enabled, so just return AARCH64_BREAK_FAULT directly in
> > these newly-added helpers if CONFIG_ARM64_LSE_ATOMICS is disabled.
> >
> > Signed-off-by: Hou Tao <houtao1@huawei.com>
>
> Hey Mark / Ard / Will / Catalin or others, could we get an Ack on patch 1 & 2
> at min if it looks good to you?
I checked the instruction encodings in patches 1 and 2 and they all look
fine to me. However, after applying those two locally I get a build failure:
| In file included from arch/arm64/net/bpf_jit_comp.c:23:
| arch/arm64/net/bpf_jit_comp.c: In function ‘build_insn’:
| arch/arm64/net/bpf_jit.h:94:2: error: implicit declaration of function ‘aarch64_insn_gen_stadd’; did you mean ‘aarch64_insn_gen_adr’? [-Werror=implicit-function-declaration]
| 94 | aarch64_insn_gen_stadd(Rn, Rs, A64_SIZE(sf))
| | ^~~~~~~~~~~~~~~~~~~~~~
| arch/arm64/net/bpf_jit_comp.c:912:9: note: in expansion of macro ‘A64_STADD’
| 912 | emit(A64_STADD(isdw, reg, src), ctx);
| | ^~~~~~~~~
| cc1: some warnings being treated as errors
Will
next prev parent reply other threads:[~2022-02-16 17:16 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-29 22:04 [PATCH bpf-next v3 0/4] bpf, arm64: support more atomic ops Hou Tao
2022-01-29 22:04 ` [PATCH bpf-next v3 1/4] arm64: move AARCH64_BREAK_FAULT into insn-def.h Hou Tao
2022-01-29 22:04 ` [PATCH bpf-next v3 2/4] arm64: insn: add encoders for atomic operations Hou Tao
2022-02-11 14:39 ` Daniel Borkmann
2022-02-15 17:42 ` Will Deacon
2022-02-16 0:21 ` Daniel Borkmann
2022-02-16 17:16 ` Will Deacon [this message]
2022-02-17 1:55 ` Hou Tao
2022-01-29 22:04 ` [PATCH bpf-next v3 3/4] bpf, arm64: support more " Hou Tao
2022-01-29 22:04 ` [PATCH bpf-next v3 4/4] selftests/bpf: use raw_tp program for atomic test Hou Tao
2022-02-15 4:25 ` [PATCH bpf-next v3 0/4] bpf, arm64: support more atomic ops Hou Tao
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