Re: [PATCH v2 net-next] bpf: arm64: remove callee-save registers use for tmp registers

From: Daniel Borkmann
Date: Tue May 17 2016 - 07:52:40 EST


On 05/17/2016 01:36 AM, Yang Shi wrote:
In the current implementation of ARM64 eBPF JIT, R23 and R24 are used for
tmp registers, which are callee-saved registers. This leads to variable size
of JIT prologue and epilogue. The latest blinding constant change prefers to
constant size of prologue and epilogue. AAPCS reserves R9 ~ R15 for temp
registers which not need to be saved/restored during function call. So, replace
R23 and R24 to R10 and R11, and remove tmp_used flag to save 2 instructions for
some jited BPF program.

CC: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Acked-by: Zi Shen Lim <zlim.lnx@xxxxxxxxx>
Signed-off-by: Yang Shi <yang.shi@xxxxxxxxxx>

LGTM, thanks!

Acked-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>