From a6f6a95f25803500079513780d11a911ce551d76 Mon Sep 17 00:00:00 2001 From: George Guo Date: Tue, 28 Mar 2023 15:13:35 +0800 Subject: LoongArch, bpf: Fix jit to skip speculation barrier opcode Just skip the opcode(BPF_ST | BPF_NOSPEC) in the BPF JIT instead of failing to JIT the entire program, given LoongArch currently has no couterpart of a speculation barrier instruction. To verify the issue, use the ltp testcase as shown below. Also, Wang says: 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.) Without this patch: $ ./bpf_prog02 [...] bpf_common.c:123: TBROK: Failed verification: ??? (524) [...] Summary: passed 0 failed 0 broken 1 skipped 0 warnings 0 With this patch: $ ./bpf_prog02 [...] Summary: passed 0 failed 0 broken 0 skipped 0 warnings 0 Fixes: 5dc615520c4d ("LoongArch: Add BPF JIT support") Signed-off-by: George Guo Signed-off-by: Daniel Borkmann Acked-by: WANG Xuerui Cc: Tiezhu Yang Link: https://lore.kernel.org/bpf/20230328071335.2664966-1-guodongtai@kylinos.cn --- arch/loongarch/net/bpf_jit.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/loongarch/net/bpf_jit.c b/arch/loongarch/net/bpf_jit.c index 288003a9f0ca..d586df48ecc6 100644 --- a/arch/loongarch/net/bpf_jit.c +++ b/arch/loongarch/net/bpf_jit.c @@ -1022,6 +1022,10 @@ 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: + break; + default: pr_err("bpf_jit: unknown opcode %02x\n", code); return -EINVAL; -- cgit v1.2.3