netdev - Re: [PATCH RESEND bpf-next v3 0/6] Zbb support and code simplification for RV64 JIT

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Message-ID: <baffbab8-721f-462a-8b58-64972f5eae70@huaweicloud.com>
Date: Mon, 22 Jan 2024 22:37:56 +0800
From: Pu Lehui <pulehui@...weicloud.com>
To: Björn Töpel <bjorn@...nel.org>, bpf@...r.kernel.org,
 linux-riscv@...ts.infradead.org, netdev@...r.kernel.org
Cc: Alexei Starovoitov <ast@...nel.org>,
 Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>,
 Martin KaFai Lau <martin.lau@...ux.dev>, Song Liu <song@...nel.org>,
 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>, Conor Dooley <conor@...nel.org>,
 Luke Nelson <luke.r.nels@...il.com>, Pu Lehui <pulehui@...wei.com>
Subject: Re: [PATCH RESEND bpf-next v3 0/6] Zbb support and code
 simplification for RV64 JIT



On 2024/1/22 22:33, Björn Töpel wrote:
> Pu Lehui <pulehui@...weicloud.com> writes:
> 
>> Add Zbb support [0] to optimize code size and performance of RV64 JIT.
>> Meanwhile, adjust the code for unification and simplification. Tests
>> test_bpf.ko and test_verifier have passed, as well as the relative
>> testcases of test_progs*.
>>
>> Link: https://github.com/riscv/riscv-bitmanip/releases/download/1.0.0/bitmanip-1.0.0-38-g865e7a7.pdf [0]
>>
>> v3 resend:
>> - resend for mail be treated as spam.
>>
>> v3:
>> - Change to early-exit code style and make code more explicit.
> 
> Lehui,
> 
> Sorry for the delay. I'm chasing a struct_ops RISC-V BPF regression in
> 6.8-rc1, I will need to wrap my head around that prior reviewing
> properly.
> 

Oh, I also found the problem with struct ops and fixed it

diff --git a/arch/riscv/net/bpf_jit_comp64.c 
b/arch/riscv/net/bpf_jit_comp64.c
index 42cfd1ed295e..5c4e0ac389d0 100644
--- a/arch/riscv/net/bpf_jit_comp64.c
+++ b/arch/riscv/net/bpf_jit_comp64.c
@@ -795,6 +795,7 @@ static int __arch_prepare_bpf_trampoline(struct 
bpf_tramp_image *im,
         struct bpf_tramp_links *fentry = &tlinks[BPF_TRAMP_FENTRY];
         struct bpf_tramp_links *fexit = &tlinks[BPF_TRAMP_FEXIT];
         struct bpf_tramp_links *fmod_ret = 
&tlinks[BPF_TRAMP_MODIFY_RETURN];
+       bool is_struct_ops = flags & BPF_TRAMP_F_INDIRECT;
         void *orig_call = func_addr;
         bool save_ret;
         u32 insn;
@@ -878,7 +879,7 @@ static int __arch_prepare_bpf_trampoline(struct 
bpf_tramp_image *im,

         stack_size = round_up(stack_size, 16);

-       if (func_addr) {
+       if (!is_struct_ops) {
                 /* For the trampoline called from function entry,
                  * the frame of traced function and the frame of
                  * trampoline need to be considered.
@@ -998,7 +999,7 @@ static int __arch_prepare_bpf_trampoline(struct 
bpf_tramp_image *im,

         emit_ld(RV_REG_S1, -sreg_off, RV_REG_FP, ctx);

-       if (func_addr) {
+       if (!is_struct_ops) {
                 /* trampoline called from function entry */
                 emit_ld(RV_REG_T0, stack_size - 8, RV_REG_SP, ctx);
                 emit_ld(RV_REG_FP, stack_size - 16, RV_REG_SP, ctx);

> 
> Björn