[PATCH net-next 2/3] arm64: bpf: optimize JMP_CALL
Will Deacon
will.deacon at arm.com
Mon Jun 6 10:05:15 PDT 2016
On Sat, Jun 04, 2016 at 03:00:29PM -0700, Zi Shen Lim wrote:
> Remove superfluous stack frame, saving us 3 instructions for
> every JMP_CALL.
>
> Signed-off-by: Zi Shen Lim <zlim.lnx at gmail.com>
> ---
> arch/arm64/net/bpf_jit_comp.c | 3 ---
> 1 file changed, 3 deletions(-)
>
> diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
> index 51abc97..7ae304e 100644
> --- a/arch/arm64/net/bpf_jit_comp.c
> +++ b/arch/arm64/net/bpf_jit_comp.c
> @@ -578,11 +578,8 @@ emit_cond_jmp:
> const u64 func = (u64)__bpf_call_base + imm;
>
> emit_a64_mov_i64(tmp, func, ctx);
> - emit(A64_PUSH(A64_FP, A64_LR, A64_SP), ctx);
> - emit(A64_MOV(1, A64_FP, A64_SP), ctx);
> emit(A64_BLR(tmp), ctx);
> emit(A64_MOV(1, r0, A64_R(0)), ctx);
> - emit(A64_POP(A64_FP, A64_LR, A64_SP), ctx);
> break;
> }
Is the jitted code intended to be unwindable by standard tools?
Will
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