[PATCH 1/2] arm64: bpf: add 'store immediate' instruction

Yang Shi
2015-11-10T23:00:57Z

aarch64 doesn't have native store immediate instruction, such operation
has to be implemented by the below instruction sequence:

Load immediate to register
Store register

Signed-off-by: Yang Shi <yang.shi@linaro.org>
CC: Zi Shen Lim <zlim.lnx@gmail.com>
CC: Xi Wang <xi.wang@gmail.com>
---
arch/arm64/net/bpf_jit_comp.c | 20 +++++++++++++++++++-
1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index 6809647..49c1f1b 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -563,7 +563,25 @@ emit_cond_jmp:
case BPF_ST | BPF_MEM | BPF_H:
case BPF_ST | BPF_MEM | BPF_B:
case BPF_ST | BPF_MEM | BPF_DW:
- goto notyet;
+ /* Load imm to a register then store it */
+ ctx->tmp_used = 1;
+ emit_a64_mov_i(1, tmp2, off, ctx);
+ emit_a64_mov_i(1, tmp, imm, ctx);
+ switch (BPF_SIZE(code)) {
+ case BPF_W:
+ emit(A64_STR32(tmp, dst, tmp2), ctx);
+ break;
+ case BPF_H:
+ emit(A64_STRH(tmp, dst, tmp2), ctx);
+ break;
+ case BPF_B:
+ emit(A64_STRB(tmp, dst, tmp2), ctx);
+ break;
+ case BPF_DW:
+ emit(A64_STR64(tmp, dst, tmp2), ctx);
+ break;
+ }
+ break;

/* STX: *(size *)(dst + off) = src */
case BPF_STX | BPF_MEM | BPF_W:
--
2.0.2