From: Peilin Ye Date: Fri, 3 Jan 2025 02:04:18 +0000 (+0000) Subject: bpf, arm64: Emit A64_{ADD,SUB}_I when possible in emit_{lse,ll_sc}_atomic() X-Git-Tag: v6.14-rc1~133^2~28 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=8c21f88407d230543435445903cfbb4d05b7b339;p=linux-block.git bpf, arm64: Emit A64_{ADD,SUB}_I when possible in emit_{lse,ll_sc}_atomic() Currently in emit_{lse,ll_sc}_atomic(), if there is an offset, we add it to the base address by doing e.g.: if (off) { emit_a64_mov_i(1, tmp, off, ctx); emit(A64_ADD(1, tmp, tmp, dst), ctx); [...] As pointed out by Xu, we can use emit_a64_add_i() (added in the previous patch) instead, which tries to combine the above into a single A64_ADD_I or A64_SUB_I when possible. Suggested-by: Xu Kuohai Signed-off-by: Peilin Ye Signed-off-by: Daniel Borkmann Acked-by: Xu Kuohai Link: https://lore.kernel.org/bpf/9ad3034a62361d91a99af24efa03f48c4c9e13ea.1735868489.git.yepeilin@google.com --- diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index 8ee9528d8795..8446848edddb 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -662,8 +662,7 @@ static int emit_lse_atomic(const struct bpf_insn *insn, struct jit_ctx *ctx) u8 reg = dst; if (off) { - emit_a64_mov_i(1, tmp, off, ctx); - emit(A64_ADD(1, tmp, tmp, dst), ctx); + emit_a64_add_i(1, tmp, reg, tmp, off, ctx); reg = tmp; } if (arena) { @@ -734,7 +733,7 @@ static int emit_ll_sc_atomic(const struct bpf_insn *insn, struct jit_ctx *ctx) const s32 imm = insn->imm; const s16 off = insn->off; const bool isdw = BPF_SIZE(code) == BPF_DW; - u8 reg; + u8 reg = dst; s32 jmp_offset; if (BPF_MODE(code) == BPF_PROBE_ATOMIC) { @@ -743,11 +742,8 @@ static int emit_ll_sc_atomic(const struct bpf_insn *insn, struct jit_ctx *ctx) return -EINVAL; } - if (!off) { - reg = dst; - } else { - emit_a64_mov_i(1, tmp, off, ctx); - emit(A64_ADD(1, tmp, tmp, dst), ctx); + if (off) { + emit_a64_add_i(1, tmp, reg, tmp, off, ctx); reg = tmp; }