arm64: introduce aarch64_insn_gen_add_sub_imm()

Introduce function to generate add/subtract (immediate) instructions.
Signed-off-by: Zi Shen Lim <zlim.lnx@gmail.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/arm64/include/asm/insn.h

@@ -75,6 +75,7 @@ enum aarch64_insn_register_type {
 	AARCH64_INSN_REGTYPE_RN,
 	AARCH64_INSN_REGTYPE_RT2,
 	AARCH64_INSN_REGTYPE_RM,
+	AARCH64_INSN_REGTYPE_RD,
 };
 
 enum aarch64_insn_register {
@@ -162,6 +163,13 @@ enum aarch64_insn_ldst_type {
 	AARCH64_INSN_LDST_STORE_PAIR_POST_INDEX,
 };
 
+enum aarch64_insn_adsb_type {
+	AARCH64_INSN_ADSB_ADD,
+	AARCH64_INSN_ADSB_SUB,
+	AARCH64_INSN_ADSB_ADD_SETFLAGS,
+	AARCH64_INSN_ADSB_SUB_SETFLAGS
+};
+
 #define	__AARCH64_INSN_FUNCS(abbr, mask, val)	\
 static __always_inline bool aarch64_insn_is_##abbr(u32 code) \
 { return (code & (mask)) == (val); } \
@@ -174,6 +182,10 @@ __AARCH64_INSN_FUNCS(stp_post,	0x7FC00000, 0x28800000)
 __AARCH64_INSN_FUNCS(ldp_post,	0x7FC00000, 0x28C00000)
 __AARCH64_INSN_FUNCS(stp_pre,	0x7FC00000, 0x29800000)
 __AARCH64_INSN_FUNCS(ldp_pre,	0x7FC00000, 0x29C00000)
+__AARCH64_INSN_FUNCS(add_imm,	0x7F000000, 0x11000000)
+__AARCH64_INSN_FUNCS(adds_imm,	0x7F000000, 0x31000000)
+__AARCH64_INSN_FUNCS(sub_imm,	0x7F000000, 0x51000000)
+__AARCH64_INSN_FUNCS(subs_imm,	0x7F000000, 0x71000000)
 __AARCH64_INSN_FUNCS(b,		0xFC000000, 0x14000000)
 __AARCH64_INSN_FUNCS(bl,	0xFC000000, 0x94000000)
 __AARCH64_INSN_FUNCS(cbz,	0xFE000000, 0x34000000)
@@ -220,6 +232,10 @@ u32 aarch64_insn_gen_load_store_pair(enum aarch64_insn_register reg1,
 				     int offset,
 				     enum aarch64_insn_variant variant,
 				     enum aarch64_insn_ldst_type type);
+u32 aarch64_insn_gen_add_sub_imm(enum aarch64_insn_register dst,
+				 enum aarch64_insn_register src,
+				 int imm, enum aarch64_insn_variant variant,
+				 enum aarch64_insn_adsb_type type);
 
 bool aarch64_insn_hotpatch_safe(u32 old_insn, u32 new_insn);
 

arch/arm64/kernel/insn.c

@@ -285,6 +285,7 @@ static u32 aarch64_insn_encode_register(enum aarch64_insn_register_type type,
 
 	switch (type) {
 	case AARCH64_INSN_REGTYPE_RT:
+	case AARCH64_INSN_REGTYPE_RD:
 		shift = 0;
 		break;
 	case AARCH64_INSN_REGTYPE_RN:
@@ -555,3 +556,46 @@ u32 aarch64_insn_gen_load_store_pair(enum aarch64_insn_register reg1,
 	return aarch64_insn_encode_immediate(AARCH64_INSN_IMM_7, insn,
 					     offset >> shift);
 }
+
+u32 aarch64_insn_gen_add_sub_imm(enum aarch64_insn_register dst,
+				 enum aarch64_insn_register src,
+				 int imm, enum aarch64_insn_variant variant,
+				 enum aarch64_insn_adsb_type type)
+{
+	u32 insn;
+
+	switch (type) {
+	case AARCH64_INSN_ADSB_ADD:
+		insn = aarch64_insn_get_add_imm_value();
+		break;
+	case AARCH64_INSN_ADSB_SUB:
+		insn = aarch64_insn_get_sub_imm_value();
+		break;
+	case AARCH64_INSN_ADSB_ADD_SETFLAGS:
+		insn = aarch64_insn_get_adds_imm_value();
+		break;
+	case AARCH64_INSN_ADSB_SUB_SETFLAGS:
+		insn = aarch64_insn_get_subs_imm_value();
+		break;
+	default:
+		BUG_ON(1);
+	}
+
+	switch (variant) {
+	case AARCH64_INSN_VARIANT_32BIT:
+		break;
+	case AARCH64_INSN_VARIANT_64BIT:
+		insn |= AARCH64_INSN_SF_BIT;
+		break;
+	default:
+		BUG_ON(1);
+	}
+
+	BUG_ON(imm & ~(SZ_4K - 1));
+
+	insn = aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RD, insn, dst);
+
+	insn = aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RN, insn, src);
+
+	return aarch64_insn_encode_immediate(AARCH64_INSN_IMM_12, insn, imm);
+}