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

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Message-ID: <CAPhsuW4dUK4NN6HqEpw7AMwaWyUwvm1a=KmDPHfQsVZ1DphYtA@mail.gmail.com>
Date: Mon, 29 Jan 2024 13:58:18 -0800
From: Song Liu <song@...nel.org>
To: Pu Lehui <pulehui@...weicloud.com>
Cc: bpf@...r.kernel.org, linux-riscv@...ts.infradead.org, 
	netdev@...r.kernel.org, Björn Töpel <bjorn@...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>
Subject: Re: [PATCH bpf-next 3/3] riscv, bpf: Use bpf_prog_pack for RV64 bpf trampoline

On Tue, Jan 23, 2024 at 2:32 AM Pu Lehui <pulehui@...weicloud.com> wrote:
>
> From: Pu Lehui <pulehui@...wei.com>
>
> 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.
>
> Link: https://lore.kernel.org/all/20231206224054.492250-1-song@kernel.org [0]
> Signed-off-by: Pu Lehui <pulehui@...wei.com>

Acked-by: Song Liu <song@...nel.org>