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Date:   Fri, 17 Apr 2020 17:22:44 -0700 (PDT)
Subject:     Re: [PATCH v5 1/9] riscv: add macro to get instruction length
In-Reply-To: <621303b9cdea215af57329b401b15750c1f683ab.1586332296.git.zong.li@sifive.com>
CC:     Paul Walmsley <paul.walmsley@sifive.com>, aou@eecs.berkeley.edu,
        mhiramat@kernel.org, linux-riscv@lists.infradead.org,
        linux-kernel@vger.kernel.org, zong.li@sifive.com
From:   Palmer Dabbelt <palmer@dabbelt.com>
To:     zong.li@sifive.com
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On Wed, 08 Apr 2020 00:56:56 PDT (-0700), zong.li@sifive.com wrote:
> Extract the calculation of instruction length for common use.
>
> Signed-off-by: Zong Li <zong.li@sifive.com>
> ---
>  arch/riscv/include/asm/bug.h | 8 ++++++++
>  arch/riscv/kernel/traps.c    | 3 ++-
>  2 files changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/arch/riscv/include/asm/bug.h b/arch/riscv/include/asm/bug.h
> index 75604fec1b1b..d6f1ec08d97b 100644
> --- a/arch/riscv/include/asm/bug.h
> +++ b/arch/riscv/include/asm/bug.h
> @@ -19,6 +19,14 @@
>  #define __BUG_INSN_32	_UL(0x00100073) /* ebreak */
>  #define __BUG_INSN_16	_UL(0x9002) /* c.ebreak */
>
> +#define GET_INSN_LENGTH(insn)						\
> +({									\
> +	unsigned long __len;						\
> +	__len = ((insn & __INSN_LENGTH_MASK) == __INSN_LENGTH_32) ?	\
> +		4UL : 2UL;						\
> +	__len;								\
> +})
> +
>  typedef u32 bug_insn_t;
>
>  #ifdef CONFIG_GENERIC_BUG_RELATIVE_POINTERS
> diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
> index ffb3d94bf0cc..a4d136355f78 100644
> --- a/arch/riscv/kernel/traps.c
> +++ b/arch/riscv/kernel/traps.c
> @@ -118,7 +118,8 @@ static inline unsigned long get_break_insn_length(unsigned long pc)
>
>  	if (probe_kernel_address((bug_insn_t *)pc, insn))
>  		return 0;
> -	return (((insn & __INSN_LENGTH_MASK) == __INSN_LENGTH_32) ? 4UL : 2UL);
> +
> +	return GET_INSN_LENGTH(insn);
>  }
>
>  asmlinkage __visible void do_trap_break(struct pt_regs *regs)

Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>