[PATCH v2] riscv: asm: use .insn for making custom instructioons

[Paul Walmsley]

Hi Ben,

On Thu, 23 Oct 2025, Ben Dooks wrote:

> The assembler has .insn for building custom instructions
> now, so remove the .4byte which also 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 at ventanamicro.com>
> Signed-off-by: Ben Dooks <ben.dooks at codethink.co.uk>
> ---
> v2:
>   - fixed #ifndef v #ifdef
>   - added custom MIPS instructions too
>   -
> ---
>  arch/riscv/include/asm/asm.h                    | 6 ++++++
>  arch/riscv/include/asm/insn-def.h               | 8 ++++----
>  arch/riscv/include/asm/vendor_extensions/mips.h | 6 +++---
>  3 files changed, 13 insertions(+), 7 deletions(-)
> 

[ ... ]

> diff --git a/arch/riscv/include/asm/insn-def.h b/arch/riscv/include/asm/insn-def.h
> index c9cfcea52cbb..a7860e6b908d 100644
> --- a/arch/riscv/include/asm/insn-def.h
> +++ b/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(_U"0x00000013")

This looks garbled.  Is this intentional?

>  #define RISCV_INSN_NOP4	_AC(0x00000013, U)
>  
> diff --git a/arch/riscv/include/asm/vendor_extensions/mips.h b/arch/riscv/include/asm/vendor_extensions/mips.h
> index ea8ca747d691..bcdce3ef3869 100644
> --- a/arch/riscv/include/asm/vendor_extensions/mips.h
> +++ b/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(".4byte 0x00301013\n\t")
> +#define MIPS_IHB	ASM_INSN_I(".4byte 0x00101013\n\t")

Same for the above two lines?


- Paul