arm64: introduce aarch64_insn_gen_load_store_pair()

Introduce function to generate load/store pair instructions.
Signed-off-by: NZi Shen Lim <zlim.lnx@gmail.com>
Acked-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

arch/arm64/include/asm/insn.h

@@ -66,12 +66,14 @@ enum aarch64_insn_imm_type {
 	AARCH64_INSN_IMM_14,
 	AARCH64_INSN_IMM_12,
 	AARCH64_INSN_IMM_9,
+	AARCH64_INSN_IMM_7,
 	AARCH64_INSN_IMM_MAX
 };
 
 enum aarch64_insn_register_type {
 	AARCH64_INSN_REGTYPE_RT,
 	AARCH64_INSN_REGTYPE_RN,
+	AARCH64_INSN_REGTYPE_RT2,
 	AARCH64_INSN_REGTYPE_RM,
 };
 
@@ -154,6 +156,10 @@ enum aarch64_insn_size_type {
 enum aarch64_insn_ldst_type {
 	AARCH64_INSN_LDST_LOAD_REG_OFFSET,
 	AARCH64_INSN_LDST_STORE_REG_OFFSET,
+	AARCH64_INSN_LDST_LOAD_PAIR_PRE_INDEX,
+	AARCH64_INSN_LDST_STORE_PAIR_PRE_INDEX,
+	AARCH64_INSN_LDST_LOAD_PAIR_POST_INDEX,
+	AARCH64_INSN_LDST_STORE_PAIR_POST_INDEX,
 };
 
 #define	__AARCH64_INSN_FUNCS(abbr, mask, val)	\
@@ -164,6 +170,10 @@ static __always_inline u32 aarch64_insn_get_##abbr##_value(void) \
 
 __AARCH64_INSN_FUNCS(str_reg,	0x3FE0EC00, 0x38206800)
 __AARCH64_INSN_FUNCS(ldr_reg,	0x3FE0EC00, 0x38606800)
+__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(b,		0xFC000000, 0x14000000)
 __AARCH64_INSN_FUNCS(bl,	0xFC000000, 0x94000000)
 __AARCH64_INSN_FUNCS(cbz,	0xFE000000, 0x34000000)
@@ -204,6 +214,12 @@ u32 aarch64_insn_gen_load_store_reg(enum aarch64_insn_register reg,
 				    enum aarch64_insn_register offset,
 				    enum aarch64_insn_size_type size,
 				    enum aarch64_insn_ldst_type type);
+u32 aarch64_insn_gen_load_store_pair(enum aarch64_insn_register reg1,
+				     enum aarch64_insn_register reg2,
+				     enum aarch64_insn_register base,
+				     int offset,
+				     enum aarch64_insn_variant variant,
+				     enum aarch64_insn_ldst_type type);
 
 bool aarch64_insn_hotpatch_safe(u32 old_insn, u32 new_insn);
 

arch/arm64/kernel/insn.c

@@ -255,6 +255,10 @@ u32 __kprobes aarch64_insn_encode_immediate(enum aarch64_insn_imm_type type,
 		mask = BIT(9) - 1;
 		shift = 12;
 		break;
+	case AARCH64_INSN_IMM_7:
+		mask = BIT(7) - 1;
+		shift = 15;
+		break;
 	default:
 		pr_err("aarch64_insn_encode_immediate: unknown immediate encoding %d\n",
 			type);
@@ -286,6 +290,9 @@ static u32 aarch64_insn_encode_register(enum aarch64_insn_register_type type,
 	case AARCH64_INSN_REGTYPE_RN:
 		shift = 5;
 		break;
+	case AARCH64_INSN_REGTYPE_RT2:
+		shift = 10;
+		break;
 	case AARCH64_INSN_REGTYPE_RM:
 		shift = 16;
 		break;
@@ -490,3 +497,61 @@ u32 aarch64_insn_gen_load_store_reg(enum aarch64_insn_register reg,
 	return aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RM, insn,
 					    offset);
 }
+
+u32 aarch64_insn_gen_load_store_pair(enum aarch64_insn_register reg1,
+				     enum aarch64_insn_register reg2,
+				     enum aarch64_insn_register base,
+				     int offset,
+				     enum aarch64_insn_variant variant,
+				     enum aarch64_insn_ldst_type type)
+{
+	u32 insn;
+	int shift;
+
+	switch (type) {
+	case AARCH64_INSN_LDST_LOAD_PAIR_PRE_INDEX:
+		insn = aarch64_insn_get_ldp_pre_value();
+		break;
+	case AARCH64_INSN_LDST_STORE_PAIR_PRE_INDEX:
+		insn = aarch64_insn_get_stp_pre_value();
+		break;
+	case AARCH64_INSN_LDST_LOAD_PAIR_POST_INDEX:
+		insn = aarch64_insn_get_ldp_post_value();
+		break;
+	case AARCH64_INSN_LDST_STORE_PAIR_POST_INDEX:
+		insn = aarch64_insn_get_stp_post_value();
+		break;
+	default:
+		BUG_ON(1);
+	}
+
+	switch (variant) {
+	case AARCH64_INSN_VARIANT_32BIT:
+		/* offset must be multiples of 4 in the range [-256, 252] */
+		BUG_ON(offset & 0x3);
+		BUG_ON(offset < -256 || offset > 252);
+		shift = 2;
+		break;
+	case AARCH64_INSN_VARIANT_64BIT:
+		/* offset must be multiples of 8 in the range [-512, 504] */
+		BUG_ON(offset & 0x7);
+		BUG_ON(offset < -512 || offset > 504);
+		shift = 3;
+		insn |= AARCH64_INSN_SF_BIT;
+		break;
+	default:
+		BUG_ON(1);
+	}
+
+	insn = aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RT, insn,
+					    reg1);
+
+	insn = aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RT2, insn,
+					    reg2);
+
+	insn = aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RN, insn,
+					    base);
+
+	return aarch64_insn_encode_immediate(AARCH64_INSN_IMM_7, insn,
+					     offset >> shift);
+}