Messages in this thread | | | Date | Tue, 28 Mar 2023 15:52:50 +0800 | Subject | Re: [PATCH v2] loongarch/bpf: Skip speculation barrier opcode, which caused ltp testcase bpf_prog02 to fail | From | WANG Xuerui <> |
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On 2023/3/28 15:22, Daniel Borkmann wrote: > On 3/28/23 9:13 AM, George Guo wrote: >> Here just skip the opcode(BPF_ST | BPF_NOSPEC) that has no couterpart >> to the loongarch. >> >> <snip> >> >> diff --git a/arch/loongarch/net/bpf_jit.c b/arch/loongarch/net/bpf_jit.c >> index 288003a9f0ca..d3c6b1c4ccbb 100644 >> --- a/arch/loongarch/net/bpf_jit.c >> +++ b/arch/loongarch/net/bpf_jit.c >> @@ -1022,6 +1022,11 @@ static int build_insn(const struct bpf_insn >> *insn, struct jit_ctx *ctx, bool ext >> emit_atomic(insn, ctx); >> break; >> + /* Speculation barrier */ >> + case BPF_ST | BPF_NOSPEC: >> + pr_info_once("bpf_jit: skip speculation barrier opcode >> %0x2x\n", code); >> + break; > > Thanks that looks better. Question to LoongArch folks (Cc): There is no > equivalent > to a speculation barrier here, correct? Either way, I think the > pr_info_once() can > just be removed given there is little value for a users to have this in > the kernel > log. I can take care of this while applying, that's fine.
I can confirm there's currently no speculation barrier equivalent on lonogarch. (Loongson says there are builtin mitigations for Spectre-V1 and V2 on their chips, and AFAIK efforts to port the exploits to mips/loongarch have all failed a few years ago.)
And yes I'd agree with removing the warning altogether. Thanks for the reviews!
Acked-by: WANG Xuerui <git@xen0n.name>
> >> default: >> pr_err("bpf_jit: unknown opcode %02x\n", code); >> return -EINVAL; >> >
-- WANG "xen0n" Xuerui
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