arm64: insn: add encoder for MOV (register)

For FTRACE_WITH_REGS, we're going to want to generate a MOV (register)
instruction as part of the callsite intialization. As MOV (register) is
an alias for ORR (shifted register), we can generate this with
aarch64_insn_gen_logical_shifted_reg(), but it's somewhat verbose and
difficult to read in-context.

Add a aarch64_insn_gen_move_reg() wrapper for this case so that we can
write callers in a more straightforward way.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Torsten Duwe <duwe@suse.de>
Tested-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Tested-by: Torsten Duwe <duwe@suse.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>

arch/arm64/include/asm/insn.h

@@ -440,6 +440,9 @@ u32 aarch64_insn_gen_logical_shifted_reg(enum aarch64_insn_register dst,
 					 int shift,
 					 enum aarch64_insn_variant variant,
 					 enum aarch64_insn_logic_type type);
+u32 aarch64_insn_gen_move_reg(enum aarch64_insn_register dst,
+			      enum aarch64_insn_register src,
+			      enum aarch64_insn_variant variant);
 u32 aarch64_insn_gen_logical_immediate(enum aarch64_insn_logic_type type,
 				       enum aarch64_insn_variant variant,
 				       enum aarch64_insn_register Rn,

arch/arm64/kernel/insn.c

@@ -1268,6 +1268,19 @@ u32 aarch64_insn_gen_logical_shifted_reg(enum aarch64_insn_register dst,
 	return aarch64_insn_encode_immediate(AARCH64_INSN_IMM_6, insn, shift);
 }
 
+/*
+ * MOV (register) is architecturally an alias of ORR (shifted register) where
+ * MOV <*d>, <*m> is equivalent to ORR <*d>, <*ZR>, <*m>
+ */
+u32 aarch64_insn_gen_move_reg(enum aarch64_insn_register dst,
+			      enum aarch64_insn_register src,
+			      enum aarch64_insn_variant variant)
+{
+	return aarch64_insn_gen_logical_shifted_reg(dst, AARCH64_INSN_REG_ZR,
+						    src, 0, variant,
+						    AARCH64_INSN_LOGIC_ORR);
+}
+
 u32 aarch64_insn_gen_adr(unsigned long pc, unsigned long addr,
 			 enum aarch64_insn_register reg,
 			 enum aarch64_insn_adr_type type)