netdev - Re: [PATCH bpf-next 0/3] Use bpf_prog

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Message-ID: <87ttmxcqm3.fsf@all.your.base.are.belong.to.us>
Date: Sun, 28 Jan 2024 18:30:44 +0100
From: Björn Töpel <bjorn@...nel.org>
To: Pu Lehui <pulehui@...weicloud.com>, bpf@...r.kernel.org,
 linux-riscv@...ts.infradead.org, netdev@...r.kernel.org
Cc: Song Liu <song@...nel.org>, Puranjay Mohan <puranjay12@...il.com>,
 Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann
 <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>, Martin KaFai
 Lau <martin.lau@...ux.dev>, Yonghong Song <yhs@...com>, John Fastabend
 <john.fastabend@...il.com>, KP Singh <kpsingh@...nel.org>, Stanislav
 Fomichev <sdf@...gle.com>, Hao Luo <haoluo@...gle.com>, Jiri Olsa
 <jolsa@...nel.org>, Palmer Dabbelt <palmer@...belt.com>, Luke Nelson
 <luke.r.nels@...il.com>, Pu Lehui <pulehui@...wei.com>, Pu Lehui
 <pulehui@...weicloud.com>
Subject: Re: [PATCH bpf-next 0/3] Use bpf_prog_pack for RV64 bpf trampoline

Pu Lehui <pulehui@...weicloud.com> writes:

> We used bpf_prog_pack to aggregate bpf programs into huge page to
> relieve the iTLB pressure on the system. We can apply it to bpf
> trampoline, as Song had been implemented it in core and x86 [0]. This
> patch is going to use bpf_prog_pack to RV64 bpf trampoline. Since Song
> and Puranjay have done a lot of work for bpf_prog_pack on RV64,
> implementing this function will be easy. But one thing to mention is
> that emit_call in RV64 will generate the maximum number of instructions
> during dry run, but during real patching it may be optimized to 1
> instruction due to distance. This is no problem as it does not overflow
> the allocated RO image.
>
> Tests about regular trampoline and struct_ops trampoline have passed, as
> well as "test_verifier" with no failure cases.
>
> Link: https://lore.kernel.org/all/20231206224054.492250-1-song@kernel.org [0]

Tested-by: Björn Töpel <bjorn@...osinc.com> #riscv