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

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Message-ID: <20250725101857.GA20688@chenghao-pc>
Date: Fri, 25 Jul 2025 18:18:57 +0800
From: Chenghao Duan <duanchenghao@...inos.cn>
To: Vincent Li <vincent.mc.li@...il.com>
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 08:30:35AM -0700, Vincent Li wrote:
> 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>

Hi Vincent,

Okay, thank you very much for your support. The existing patch has
included "Tested-by: Vincent Li vincent.mc.li@...il.com".

Brs Chenghao