On 10/10/24 1:21 PM, Alexei Starovoitov wrote:
On Thu, Oct 10, 2024 at 10:56 AM Yonghong Song <yonghong.song@xxxxxxxxx> wrote:Two helpers are extracted from bpf/x86 jit: - a helper to handle 'reg1 <op>= reg2' where <op> is add/sub/and/or/xor - a helper to handle 'reg *= imm' Both helpers will be used in the subsequent patch. Signed-off-by: Yonghong Song <yonghong.song@xxxxxxxxx> --- arch/x86/net/bpf_jit_comp.c | 51 ++++++++++++++++++++++++------------- 1 file changed, 34 insertions(+), 17 deletions(-) diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index a6ba85cec49a..297dd64f4b6a 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -1475,6 +1475,37 @@ static void emit_alu_helper_1(u8 **pprog, u8 insn_code, u32 dst_reg, s32 imm32) *pprog = prog; } +/* emit ADD/SUB/AND/OR/XOR 'reg1 <op>= reg2' operations */ +static void emit_alu_helper_2(u8 **pprog, u8 insn_code, u32 dst_reg, u32 src_reg) +{ + u8 b2 = 0; + u8 *prog = *pprog; + + maybe_emit_mod(&prog, dst_reg, src_reg, + BPF_CLASS(insn_code) == BPF_ALU64); + b2 = simple_alu_opcodes[BPF_OP(insn_code)]; + EMIT2(b2, add_2reg(0xC0, dst_reg, src_reg)); + + *pprog = prog; +} + +/* emit 'reg *= imm' operations */ +static void emit_alu_helper_3(u8 **pprog, u8 insn_code, u32 dst_reg, s32 imm32)_1, _2, _3 ?! There must be a better way to name the helpers. Like: _1 -> emit_alu_imm _2 -> emit_alu_reg _3 -> emit_mul_imm
I struggle to get a proper name here. I originally thought about to use emit_alu_reg_imm, emit_alu_reg_reg, but in my case, even emit_alu_reg_imm only supports add/sub/and/or/xor and it does not support mul/div/mod, so emit_alu_reg_imm does not really cover all alu operations so I chose another name which is also not good. I guess I can use the above you suggested in the above which actually covers most alu operations.
