From: Brendan Jackman <jackmanb@google.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: bpf@vger.kernel.org, Alexei Starovoitov <ast@kernel.org>,
Yonghong Song <yhs@fb.com>,
Daniel Borkmann <daniel@iogearbox.net>,
KP Singh <kpsingh@chromium.org>,
Florent Revest <revest@chromium.org>
Subject: Re: [PATCH 3/7] bpf: Rename BPF_XADD and prepare to encode other atomics in .imm
Date: Tue, 24 Nov 2020 11:21:30 +0000 [thread overview]
Message-ID: <20201124112130.GD1883487@google.com> (raw)
In-Reply-To: <20201124065004.pdgjfkqvzywb5l2c@ast-mbp>
On Mon, Nov 23, 2020 at 10:50:04PM -0800, Alexei Starovoitov wrote:
> On Mon, Nov 23, 2020 at 05:31:58PM +0000, Brendan Jackman wrote:
> > A subsequent patch will add additional atomic operations. These new
> > operations will use the same opcode field as the existing XADD, with
> > the immediate discriminating different operations.
> >
> > In preparation, rename the instruction mode BPF_ATOMIC and start
> > calling the zero immediate BPF_ADD.
> >
> > This is possible (doesn't break existing valid BPF progs) because the
> > immediate field is currently reserved MBZ and BPF_ADD is zero.
> >
> > All uses are removed from the tree but the BPF_XADD definition is
> > kept around to avoid breaking builds for people including kernel
> > headers.
> >
> > Signed-off-by: Brendan Jackman <jackmanb@google.com>
> > ---
> > Documentation/networking/filter.rst | 27 +++++++++-------
> > arch/arm/net/bpf_jit_32.c | 7 ++---
> > arch/arm64/net/bpf_jit_comp.c | 16 +++++++---
> > arch/mips/net/ebpf_jit.c | 11 +++++--
> > arch/powerpc/net/bpf_jit_comp64.c | 25 ++++++++++++---
> > arch/riscv/net/bpf_jit_comp32.c | 20 +++++++++---
> > arch/riscv/net/bpf_jit_comp64.c | 16 +++++++---
> > arch/s390/net/bpf_jit_comp.c | 26 +++++++++-------
> > arch/sparc/net/bpf_jit_comp_64.c | 14 +++++++--
> > arch/x86/net/bpf_jit_comp.c | 30 +++++++++++-------
> > arch/x86/net/bpf_jit_comp32.c | 6 ++--
>
> I think this massive rename is not needed.
> BPF_XADD is uapi and won't be removed.
> Updating documentation, samples and tests is probably enough.
Ack, will tone down my agression against BPF_XADD! However the majority
of these changes are to various JITs, which do need to be updated, since
they need to check for nonzero immediate fields. Do you think I should
keep the renames where we're touching the code anyway?
next prev parent reply other threads:[~2020-11-24 11:22 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-23 17:31 [PATCH 0/7] Atomics for eBPF Brendan Jackman
2020-11-23 17:31 ` [PATCH 1/7] bpf: Factor out emission of ModR/M for *(reg + off) Brendan Jackman
2020-11-23 17:31 ` [PATCH 2/7] bpf: x86: Factor out emission of REX byte Brendan Jackman
2020-11-23 17:31 ` [PATCH 3/7] bpf: Rename BPF_XADD and prepare to encode other atomics in .imm Brendan Jackman
2020-11-23 23:54 ` Yonghong Song
2020-11-24 11:02 ` Brendan Jackman
2020-11-24 16:04 ` Yonghong Song
2020-11-24 3:28 ` kernel test robot
2020-11-24 6:50 ` Alexei Starovoitov
2020-11-24 11:21 ` Brendan Jackman [this message]
2020-11-24 22:43 ` Alexei Starovoitov
2020-11-23 17:31 ` [PATCH 4/7] bpf: Move BPF_STX reserved field check into BPF_STX verifier code Brendan Jackman
2020-11-23 17:32 ` [PATCH 5/7] bpf: Add BPF_FETCH field / create atomic_fetch_add instruction Brendan Jackman
2020-11-23 21:12 ` kernel test robot
2020-11-23 21:51 ` kernel test robot
2020-11-24 6:52 ` Alexei Starovoitov
2020-11-24 10:48 ` Brendan Jackman
2020-11-23 17:32 ` [PATCH 6/7] bpf: Add instructions for atomic_cmpxchg and friends Brendan Jackman
2020-11-23 19:29 ` Brendan Jackman
2020-11-24 6:40 ` Alexei Starovoitov
2020-11-24 10:55 ` Brendan Jackman
2020-11-24 22:51 ` Alexei Starovoitov
2020-11-23 17:32 ` [PATCH 7/7] bpf: Add tests for new BPF atomic operations Brendan Jackman
2020-11-24 0:26 ` Yonghong Song
2020-11-24 13:10 ` Brendan Jackman
2020-11-23 17:36 ` [PATCH 0/7] Atomics for eBPF Brendan Jackman
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