linux-kernel - Re: [PATCH v4 0/5] Support trampoline for LoongArch

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Message-ID: <CAK3+h2zirm6cV2tAbd38RSYSF3=B1qZ+9jm_GZPsAPrMtaozmg@mail.gmail.com>
Date: Thu, 24 Jul 2025 08:30:35 -0700
From: Vincent Li <vincent.mc.li@...il.com>
To: Chenghao Duan <duanchenghao@...inos.cn>
Cc: ast@...nel.org, daniel@...earbox.net, andrii@...nel.org, 
	yangtiezhu@...ngson.cn, hengqi.chen@...il.com, chenhuacai@...nel.org, 
	martin.lau@...ux.dev, eddyz87@...il.com, song@...nel.org, 
	yonghong.song@...ux.dev, john.fastabend@...il.com, kpsingh@...nel.org, 
	sdf@...ichev.me, haoluo@...gle.com, jolsa@...nel.org, kernel@...0n.name, 
	linux-kernel@...r.kernel.org, loongarch@...ts.linux.dev, bpf@...r.kernel.org, 
	guodongtai@...inos.cn, youling.tang@...ux.dev, jianghaoran@...inos.cn
Subject: Re: [PATCH v4 0/5] Support trampoline for LoongArch

On Thu, Jul 24, 2025 at 7:19 AM Chenghao Duan <duanchenghao@...inos.cn> wrote:
>
> v4:
> 1. Delete the #3 patch of version V3.
>
> 2. Add 5 NOP instructions in build_prologue().
>    Reserve space for the move_imm + jirl instruction.
>
> 3. Differentiate between direct jumps and ftrace jumps of trampoline:
>    direct jumps skip 5 instructions.
>    ftrace jumps skip 2 instructions.
>
> 4. Remove the generation of BL jump instructions in emit_jump_and_link().
>    After the trampoline ends, it will jump to the specified register.
>    The BL instruction writes PC+4 to r1 instead of allowing the
>    specification of rd.
>
> -----------------------------------------------------------------------
> Historical Version:
> v3:
> 1. Patch 0003 adds EXECMEM_BPF memory type to the execmem subsystem.
>
> 2. Align the size calculated by arch_bpf_trampoline_size to page
> boundaries.
>
> 3. Add the flush icache operation to larch_insn_text_copy.
>
> 4. Unify the implementation of bpf_arch_xxx into the patch
> "0004-LoongArch-BPF-Add-bpf_arch_xxxxx-support-for-Loong.patch".
>
> 5. Change the patch order. Move the patch
> "0002-LoongArch-BPF-Update-the-code-to-rename-validate_.patch" before
> "0005-LoongArch-BPF-Add-bpf-trampoline-support-for-Loon.patch".
>
> URL for version v3:
> https://lore.kernel.org/all/20250709055029.723243-1-duanchenghao@kylinos.cn/
> ---------
> v2:
> 1. Change the fixmap in the instruction copy function to set_memory_xxx.
>
> 2. Change the implementation method of the following code.
>         - arch_alloc_bpf_trampoline
>         - arch_free_bpf_trampoline
>         Use the BPF core's allocation and free functions.
>
>         - bpf_arch_text_invalidate
>         Operate with the function larch_insn_text_copy that carries
>         memory attribute modifications.
>
> 3. Correct the incorrect code formatting.
>
> URL for version v2:
> https://lore.kernel.org/all/20250618105048.1510560-1-duanchenghao@kylinos.cn/
> ---------
> v1:
> Support trampoline for LoongArch. The following feature tests have been
> completed:
>         1. fentry
>         2. fexit
>         3. fmod_ret
>
> TODO: The support for the struct_ops feature will be provided in
> subsequent patches.
>
> URL for version v1:
> https://lore.kernel.org/all/20250611035952.111182-1-duanchenghao@kylinos.cn/
> -----------------------------------------------------------------------
>
> Chenghao Duan (4):
>   LoongArch: Add larch_insn_gen_{beq,bne} helpers
>   LoongArch: BPF: Update the code to rename validate_code to
>     validate_ctx
>   LoongArch: BPF: Add bpf_arch_xxxxx support for Loongarch
>   LoongArch: BPF: Add bpf trampoline support for Loongarch
>
> Tiezhu Yang (1):
>   LoongArch: BPF: Add struct ops support for trampoline
>
>  arch/loongarch/include/asm/inst.h |   3 +
>  arch/loongarch/kernel/inst.c      |  60 ++++
>  arch/loongarch/net/bpf_jit.c      | 521 +++++++++++++++++++++++++++++-
>  arch/loongarch/net/bpf_jit.h      |   6 +
>  4 files changed, 589 insertions(+), 1 deletion(-)
>
> --
> 2.25.1
>

Tested the whole patch series and it resolved the xdp-tool xdp-filter issue

[root@...ora ~]# xdp-loader status
CURRENT XDP PROGRAM STATUS:

Interface        Prio  Program name      Mode     ID   Tag
  Chain actions
--------------------------------------------------------------------------------------
lo                     xdp_dispatcher    skb      53   4d7e87c0d30db711
 =>              10     xdpfilt_alw_all           62
320c53c06933a8fa  XDP_PASS
dummy0                 <No XDP program loaded!>
sit0                   <No XDP program loaded!>
enp0s3f0               <No XDP program loaded!>
wlp3s0                 <No XDP program loaded!>

you can add Tested-by: Vincent Li <vincent.mc.li@...il.com>