Thread (11 messages) flat view 11 messages, 4 authors, 2016-06-07

Re: [PATCH net-next 2/3] arm64: bpf: optimize JMP_CALL

From: Will Deacon <hidden>
Date: 2016-06-06 17:05:02
Also in: linux-arm-kernel, lkml

On Sat, Jun 04, 2016 at 03:00:29PM -0700, Zi Shen Lim wrote:
quoted hunk ↗ jump to hunk
Remove superfluous stack frame, saving us 3 instructions for
every JMP_CALL.

Signed-off-by: Zi Shen Lim <redacted>
---
 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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