linux-kernel - Re: [PATCH v11 6/6] LoongArch: Use common function sign

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Message-ID: <CAAhV-H768YCCdpn62tBAzbT0W24KNK-vnFnPDmMW-+X5_EdxgA@mail.gmail.com>
Date:   Mon, 16 Jan 2023 11:18:02 +0800
From:   Huacai Chen <chenhuacai@...nel.org>
To:     Tiezhu Yang <yangtiezhu@...ngson.cn>
Cc:     WANG Xuerui <kernel@...0n.name>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        loongarch@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v11 6/6] LoongArch: Use common function sign_extend64()

I queued this patch, but others need more reviews.

Huacai

On Sat, Jan 14, 2023 at 5:27 PM Tiezhu Yang <yangtiezhu@...ngson.cn> wrote:
>
> There exists a common function sign_extend64() to sign extend a 64-bit
> value using specified bit as sign-bit in include/linux/bitops.h, it is
> more efficient, let us use it and remove the arch-specific sign_extend()
> under arch/loongarch.
>
> Suggested-by: Jinyang He <hejinyang@...ngson.cn>
> Signed-off-by: Tiezhu Yang <yangtiezhu@...ngson.cn>
> ---
>  arch/loongarch/include/asm/inst.h   | 8 --------
>  arch/loongarch/kernel/alternative.c | 6 +++---
>  2 files changed, 3 insertions(+), 11 deletions(-)
>
> diff --git a/arch/loongarch/include/asm/inst.h b/arch/loongarch/include/asm/inst.h
> index e0771d2..ba18ce8 100644
> --- a/arch/loongarch/include/asm/inst.h
> +++ b/arch/loongarch/include/asm/inst.h
> @@ -397,14 +397,6 @@ static inline bool unsigned_imm_check(unsigned long val, unsigned int bit)
>         return val < (1UL << bit);
>  }
>
> -static inline unsigned long sign_extend(unsigned long val, unsigned int idx)
> -{
> -       if (!is_imm_negative(val, idx + 1))
> -               return ((1UL << idx) - 1) & val;
> -       else
> -               return ~((1UL << idx) - 1) | val;
> -}
> -
>  #define DEF_EMIT_REG0I26_FORMAT(NAME, OP)                              \
>  static inline void emit_##NAME(union loongarch_instruction *insn,      \
>                                int offset)                              \
> diff --git a/arch/loongarch/kernel/alternative.c b/arch/loongarch/kernel/alternative.c
> index c5aebea..4ad1384 100644
> --- a/arch/loongarch/kernel/alternative.c
> +++ b/arch/loongarch/kernel/alternative.c
> @@ -74,7 +74,7 @@ static void __init_or_module recompute_jump(union loongarch_instruction *buf,
>         switch (src->reg0i26_format.opcode) {
>         case b_op:
>         case bl_op:
> -               jump_addr = cur_pc + sign_extend((si_h << 16 | si_l) << 2, 27);
> +               jump_addr = cur_pc + sign_extend64((si_h << 16 | si_l) << 2, 27);
>                 if (in_alt_jump(jump_addr, start, end))
>                         return;
>                 offset = jump_addr - pc;
> @@ -93,7 +93,7 @@ static void __init_or_module recompute_jump(union loongarch_instruction *buf,
>                 fallthrough;
>         case beqz_op:
>         case bnez_op:
> -               jump_addr = cur_pc + sign_extend((si_h << 16 | si_l) << 2, 22);
> +               jump_addr = cur_pc + sign_extend64((si_h << 16 | si_l) << 2, 22);
>                 if (in_alt_jump(jump_addr, start, end))
>                         return;
>                 offset = jump_addr - pc;
> @@ -112,7 +112,7 @@ static void __init_or_module recompute_jump(union loongarch_instruction *buf,
>         case bge_op:
>         case bltu_op:
>         case bgeu_op:
> -               jump_addr = cur_pc + sign_extend(si << 2, 17);
> +               jump_addr = cur_pc + sign_extend64(si << 2, 17);
>                 if (in_alt_jump(jump_addr, start, end))
>                         return;
>                 offset = jump_addr - pc;
> --
> 2.1.0
>