riscv: asm: use .insn for making custom instructions

The assembler has .insn for building custom instructions
now, so change the .4byte to .insn. This ensures the output
is marked as an instruction and not as data which may
confuse both debuggers and anything else that relies on
this sort of marking.

Add an ASM_INSN_I() wrapper in asm.h to allow the selecting
of how this is output so older assemblers are still good.

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Link: https://lore.kernel.org/r/20251024171640.65232-1-ben.dooks@codethink.co.uk
Signed-off-by: Paul Walmsley <pjw@kernel.org>

Author: bjdooks-ct

arch/riscv/include/asm/asm.h

@@ -12,6 +12,12 @@
 #define __ASM_STR(x)	#x
 #endif
 
+#ifdef CONFIG_AS_HAS_INSN
+#define ASM_INSN_I(__x) ".insn " __x
+#else
+#define ASM_INSN_I(__x) ".4byte " __x
+#endif
+
 #if __riscv_xlen == 64
 #define __REG_SEL(a, b)	__ASM_STR(a)
 #elif __riscv_xlen == 32

arch/riscv/include/asm/insn-def.h

@@ -256,10 +256,10 @@
 	INSN_S(OPCODE_OP_IMM, FUNC3(6), __RS2(3),		\
 	       SIMM12((offset) & 0xfe0), RS1(base))
 
-#define RISCV_PAUSE	".4byte 0x100000f"
-#define ZAWRS_WRS_NTO	".4byte 0x00d00073"
-#define ZAWRS_WRS_STO	".4byte 0x01d00073"
-#define RISCV_NOP4	".4byte 0x00000013"
+#define RISCV_PAUSE	ASM_INSN_I("0x100000f")
+#define ZAWRS_WRS_NTO	ASM_INSN_I("0x00d00073")
+#define ZAWRS_WRS_STO	ASM_INSN_I("0x01d00073")
+#define RISCV_NOP4	ASM_INSN_I("0x00000013")
 
 #define RISCV_INSN_NOP4	_AC(0x00000013, U)
 

arch/riscv/include/asm/vendor_extensions/mips.h

@@ -30,8 +30,8 @@ extern struct riscv_isa_vendor_ext_data_list riscv_isa_vendor_ext_list_mips;
  * allowing any subsequent instructions to fetch.
  */
 
-#define MIPS_PAUSE	".4byte 0x00501013\n\t"
-#define MIPS_EHB	".4byte 0x00301013\n\t"
-#define MIPS_IHB	".4byte 0x00101013\n\t"
+#define MIPS_PAUSE	ASM_INSN_I("0x00501013\n\t")
+#define MIPS_EHB	ASM_INSN_I("0x00301013\n\t")
+#define MIPS_IHB	ASM_INSN_I("0x00101013\n\t")
 
 #endif // _ASM_RISCV_VENDOR_EXTENSIONS_MIPS_H