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authorLuke Nelson <lukenels@cs.washington.edu>2020-05-05 17:03:18 -0700
committerDaniel Borkmann <daniel@iogearbox.net>2020-05-06 09:48:15 +0200
commit21a099abb765c3754689e1f7ca4536fa560112d0 (patch)
treec6d2bc71c49617d48dd2d01a93821de4d6162349 /arch
parent0224b2acea0f9e3908d33e27b2dcb4e04686e997 (diff)
bpf, riscv: Optimize FROM_LE using verifier_zext on RV64
This patch adds two optimizations for BPF_ALU BPF_END BPF_FROM_LE in the RV64 BPF JIT. First, it enables the verifier zero-extension optimization to avoid zero extension when imm == 32. Second, it avoids generating code for imm == 64, since it is equivalent to a no-op. Co-developed-by: Xi Wang <xi.wang@gmail.com> Signed-off-by: Xi Wang <xi.wang@gmail.com> Signed-off-by: Luke Nelson <luke.r.nels@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Björn Töpel <bjorn.topel@gmail.com> Acked-by: Björn Töpel <bjorn.topel@gmail.com> Link: https://lore.kernel.org/bpf/20200506000320.28965-3-luke.r.nels@gmail.com
Diffstat (limited to 'arch')
-rw-r--r--arch/riscv/net/bpf_jit_comp64.c20
1 files changed, 14 insertions, 6 deletions
diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c
index e2636902a74e..c3ce9a911b66 100644
--- a/arch/riscv/net/bpf_jit_comp64.c
+++ b/arch/riscv/net/bpf_jit_comp64.c
@@ -542,13 +542,21 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
/* dst = BSWAP##imm(dst) */
case BPF_ALU | BPF_END | BPF_FROM_LE:
- {
- int shift = 64 - imm;
-
- emit(rv_slli(rd, rd, shift), ctx);
- emit(rv_srli(rd, rd, shift), ctx);
+ switch (imm) {
+ case 16:
+ emit(rv_slli(rd, rd, 48), ctx);
+ emit(rv_srli(rd, rd, 48), ctx);
+ break;
+ case 32:
+ if (!aux->verifier_zext)
+ emit_zext_32(rd, ctx);
+ break;
+ case 64:
+ /* Do nothing */
+ break;
+ }
break;
- }
+
case BPF_ALU | BPF_END | BPF_FROM_BE:
emit(rv_addi(RV_REG_T2, RV_REG_ZERO, 0), ctx);