bpf: arm64: remove callee-save registers use for tmp registers
authorYang Shi <yang.shi@linaro.org>
Mon, 16 May 2016 23:36:26 +0000 (16:36 -0700)
committerDavid S. Miller <davem@davemloft.net>
Tue, 17 May 2016 18:03:33 +0000 (14:03 -0400)
commit4c1cd4fdfd14ecd417962f8c2166506132697f7c
tree14fba1a53e6426a3e4c12773dacd5fe81780b3b3
parentcd9e2e5d3ff148be9ea210f622ce3e8e8292fcd6
bpf: arm64: remove callee-save registers use for tmp registers

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@iogearbox.net>
Acked-by: Zi Shen Lim <zlim.lnx@gmail.com>
Signed-off-by: Yang Shi <yang.shi@linaro.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
arch/arm64/net/bpf_jit_comp.c