This patch series introduces a set of optimizations to the BPF JIT
on RV64. The optimizations are related to the verifier zero-extension
optimization and BPF_JMP BPF_K.
We tested the optimizations on a QEMU riscv64 virt machine, using
lib/test_bpf and test_verifier, and formally verified their correctness
using Serval.
Luke Nelson (4):
bpf, riscv: Enable missing verifier_zext optimizations on RV64
bpf, riscv: Optimize FROM_LE using verifier_zext on RV64
bpf, riscv: Optimize BPF_JMP BPF_K when imm == 0 on RV64
bpf, riscv: Optimize BPF_JSET BPF_K using andi on RV64
arch/riscv/net/bpf_jit_comp64.c | 64 ++++++++++++++++++++++-----------
1 file changed, 44 insertions(+), 20 deletions(-)
Cc: Xi Wang <[email protected]>
--
2.17.1
This patch adds an optimization to BPF_JMP (32- and 64-bit) BPF_K for
when the BPF immediate is zero.
When the immediate is zero, the code can directly use the RISC-V zero
register instead of loading a zero immediate to a temporary register
first.
Co-developed-by: Xi Wang <[email protected]>
Signed-off-by: Xi Wang <[email protected]>
Signed-off-by: Luke Nelson <[email protected]>
---
arch/riscv/net/bpf_jit_comp64.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c
index c3ce9a911b66..b07cef952019 100644
--- a/arch/riscv/net/bpf_jit_comp64.c
+++ b/arch/riscv/net/bpf_jit_comp64.c
@@ -796,7 +796,13 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
case BPF_JMP32 | BPF_JSET | BPF_K:
rvoff = rv_offset(i, off, ctx);
s = ctx->ninsns;
- emit_imm(RV_REG_T1, imm, ctx);
+ if (imm) {
+ emit_imm(RV_REG_T1, imm, ctx);
+ rs = RV_REG_T1;
+ } else {
+ /* If imm is 0, simply use zero register. */
+ rs = RV_REG_ZERO;
+ }
if (!is64) {
if (is_signed_bpf_cond(BPF_OP(code)))
emit_sext_32_rd(&rd, ctx);
@@ -811,11 +817,10 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
if (BPF_OP(code) == BPF_JSET) {
/* Adjust for and */
rvoff -= 4;
- emit(rv_and(RV_REG_T1, rd, RV_REG_T1), ctx);
- emit_branch(BPF_JNE, RV_REG_T1, RV_REG_ZERO, rvoff,
- ctx);
+ emit(rv_and(rs, rd, rs), ctx);
+ emit_branch(BPF_JNE, rs, RV_REG_ZERO, rvoff, ctx);
} else {
- emit_branch(BPF_OP(code), rd, RV_REG_T1, rvoff, ctx);
+ emit_branch(BPF_OP(code), rd, rs, rvoff, ctx);
}
break;
--
2.17.1
On Wed, 6 May 2020 at 02:03, Luke Nelson <[email protected]> wrote:
>
> This patch series introduces a set of optimizations to the BPF JIT
> on RV64. The optimizations are related to the verifier zero-extension
> optimization and BPF_JMP BPF_K.
>
> We tested the optimizations on a QEMU riscv64 virt machine, using
> lib/test_bpf and test_verifier, and formally verified their correctness
> using Serval.
>
Luke and Xi,
Thanks a lot for working on this! Very nice series!
For the series:
Reviewed-by: Björn Töpel <[email protected]>
Acked-by: Björn Töpel <[email protected]>
> Luke Nelson (4):
> bpf, riscv: Enable missing verifier_zext optimizations on RV64
> bpf, riscv: Optimize FROM_LE using verifier_zext on RV64
> bpf, riscv: Optimize BPF_JMP BPF_K when imm == 0 on RV64
> bpf, riscv: Optimize BPF_JSET BPF_K using andi on RV64
>
> arch/riscv/net/bpf_jit_comp64.c | 64 ++++++++++++++++++++++-----------
> 1 file changed, 44 insertions(+), 20 deletions(-)
>
> Cc: Xi Wang <[email protected]>
>
> --
> 2.17.1
>
On 5/6/20 9:08 AM, Björn Töpel wrote:
> On Wed, 6 May 2020 at 02:03, Luke Nelson <[email protected]> wrote:
>>
>> This patch series introduces a set of optimizations to the BPF JIT
>> on RV64. The optimizations are related to the verifier zero-extension
>> optimization and BPF_JMP BPF_K.
>>
>> We tested the optimizations on a QEMU riscv64 virt machine, using
>> lib/test_bpf and test_verifier, and formally verified their correctness
>> using Serval.
>>
>
> Luke and Xi,
>
> Thanks a lot for working on this! Very nice series!
>
> For the series:
> Reviewed-by: Björn Töpel <[email protected]>
> Acked-by: Björn Töpel <[email protected]>
>
>> Luke Nelson (4):
>> bpf, riscv: Enable missing verifier_zext optimizations on RV64
>> bpf, riscv: Optimize FROM_LE using verifier_zext on RV64
>> bpf, riscv: Optimize BPF_JMP BPF_K when imm == 0 on RV64
>> bpf, riscv: Optimize BPF_JSET BPF_K using andi on RV64
>>
>> arch/riscv/net/bpf_jit_comp64.c | 64 ++++++++++++++++++++++-----------
>> 1 file changed, 44 insertions(+), 20 deletions(-)
>>
>> Cc: Xi Wang <[email protected]>
Applied, thanks everyone!