[RFC PATCH -next v2 1/4] arm64: introduce aarch64_insn_gen_load_literal

[Wang ShaoBo <bobo.shaobowang@huawei.com>]

From: Cheng Jian <cj.chengjian@huawei.com>

This introduces helper to generate ldr(literal) instructions.

	LDR <Xt>, <label>

Signed-off-by: Cheng Jian <cj.chengjian@huawei.com>
Signed-off-by: Wang ShaoBo <bobo.shaobowang@huawei.com>
---
 arch/arm64/include/asm/insn.h |  6 +++++
 arch/arm64/lib/insn.c         | 49 +++++++++++++++++++++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/arch/arm64/include/asm/insn.h b/arch/arm64/include/asm/insn.h
index 6b776c8667b2..95b3562843c2 100644
--- a/arch/arm64/include/asm/insn.h
+++ b/arch/arm64/include/asm/insn.h
@@ -458,6 +458,9 @@ u32 aarch64_insn_gen_hint(enum aarch64_insn_hint_cr_op op);
 u32 aarch64_insn_gen_nop(void);
 u32 aarch64_insn_gen_branch_reg(enum aarch64_insn_register reg,
 				enum aarch64_insn_branch_type type);
+u32 aarch64_insn_gen_load_literal(enum aarch64_insn_register reg,
+				  enum aarch64_insn_variant variant,
+				  long offset);
 u32 aarch64_insn_gen_load_store_reg(enum aarch64_insn_register reg,
 				    enum aarch64_insn_register base,
 				    enum aarch64_insn_register offset,
@@ -544,6 +547,9 @@ u32 aarch64_insn_gen_prefetch(enum aarch64_insn_register base,
 s32 aarch64_get_branch_offset(u32 insn);
 u32 aarch64_set_branch_offset(u32 insn, s32 offset);
 
+s32 aarch64_insn_get_ldr_lit_offset(u32 insn);
+u32 aarch64_insn_set_ldr_lit_offset(u32 insn, u32 offset);
+
 s32 aarch64_insn_adrp_get_offset(u32 insn);
 u32 aarch64_insn_adrp_set_offset(u32 insn, s32 offset);
 
diff --git a/arch/arm64/lib/insn.c b/arch/arm64/lib/insn.c
index fccfe363e567..9ac5fb4e76e8 100644
--- a/arch/arm64/lib/insn.c
+++ b/arch/arm64/lib/insn.c
@@ -17,6 +17,7 @@
 #include <asm/kprobes.h>
 
 #define AARCH64_INSN_SF_BIT	BIT(31)
+#define AARCH64_INSN_OPC_BIT	BIT(30)
 #define AARCH64_INSN_N_BIT	BIT(22)
 #define AARCH64_INSN_LSL_12	BIT(22)
 
@@ -473,6 +474,54 @@ u32 aarch64_insn_gen_branch_reg(enum aarch64_insn_register reg,
 	return aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RN, insn, reg);
 }
 
+s32 aarch64_insn_get_ldr_lit_offset(u32 insn)
+{
+	s32 imm;
+
+	if (aarch64_insn_is_ldr_lit(insn)) {
+		imm = aarch64_insn_decode_immediate(AARCH64_INSN_IMM_19, insn);
+		return (imm << 13) >> 11;
+	}
+
+	/* Unhandled instruction */
+	BUG();
+}
+
+u32 aarch64_insn_set_ldr_lit_offset(u32 insn, u32 offset)
+{
+	if (aarch64_insn_is_ldr_lit(insn))
+		return aarch64_insn_encode_immediate(AARCH64_INSN_IMM_19, insn,
+						     offset >> 2);
+	/* Unhandled instruction */
+	BUG();
+}
+
+u32 aarch64_insn_gen_load_literal(enum aarch64_insn_register reg,
+				  enum aarch64_insn_variant variant,
+				  long offset)
+{
+	u32 insn;
+
+	insn = aarch64_insn_get_ldr_lit_value();
+
+	switch (variant) {
+	case AARCH64_INSN_VARIANT_32BIT:
+		/* 32-bit ops == 00 */
+		break;
+	case AARCH64_INSN_VARIANT_64BIT:
+		/* 64-bit opc == 01 */
+		insn |= AARCH64_INSN_OPC_BIT;
+		break;
+	default:
+		pr_err("%s: unknown variant encoding %d\n", __func__, variant);
+		return AARCH64_BREAK_FAULT;
+	}
+
+	insn = aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RT, insn, reg);
+
+	return aarch64_insn_set_ldr_lit_offset(insn, offset);
+}
+
 u32 aarch64_insn_gen_load_store_reg(enum aarch64_insn_register reg,
 				    enum aarch64_insn_register base,
 				    enum aarch64_insn_register offset,
-- 
2.25.1