bpf: arm64: remove callee-save registers use for tmp registers

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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>

...

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Yang Shi 2016-05-16 16:36:26 -07:00 • committed by David S. Miller

parent cd9e2e5d3f

commit 4c1cd4fdfd

1 changed files with 5 additions and 29 deletions

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arch/arm64/net/bpf_jit_comp.c

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