linux-kernel - Re: [PATCH 02/15] riscv: cleanup do_trap_break

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Date:   Fri, 18 Oct 2019 08:21:08 +0530
From:   Anup Patel <anup@...infault.org>
To:     Christoph Hellwig <hch@....de>
Cc:     Palmer Dabbelt <palmer@...ive.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Damien Le Moal <damien.lemoal@....com>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org List" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 02/15] riscv: cleanup do_trap_break

On Thu, Oct 17, 2019 at 11:07 PM Christoph Hellwig <hch@....de> wrote:
>
> If we always compile the get_break_insn_length inline function we can
> remove the ifdefs and let dead code elimination take care of the warn
> branch that is now unreadable because the report_bug stub always
> returns BUG_TRAP_TYPE_BUG.
>
> Signed-off-by: Christoph Hellwig <hch@....de>
> ---
>  arch/riscv/kernel/traps.c | 26 ++++++--------------------
>  1 file changed, 6 insertions(+), 20 deletions(-)
>
> diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
> index 1ac75f7d0bff..10a17e545f43 100644
> --- a/arch/riscv/kernel/traps.c
> +++ b/arch/riscv/kernel/traps.c
> @@ -111,7 +111,6 @@ DO_ERROR_INFO(do_trap_ecall_s,
>  DO_ERROR_INFO(do_trap_ecall_m,
>         SIGILL, ILL_ILLTRP, "environment call from M-mode");
>
> -#ifdef CONFIG_GENERIC_BUG
>  static inline unsigned long get_break_insn_length(unsigned long pc)
>  {
>         bug_insn_t insn;
> @@ -120,28 +119,15 @@ static inline unsigned long get_break_insn_length(unsigned long pc)
>                 return 0;
>         return (((insn & __INSN_LENGTH_MASK) == __INSN_LENGTH_32) ? 4UL : 2UL);
>  }
> -#endif /* CONFIG_GENERIC_BUG */
>
>  asmlinkage void do_trap_break(struct pt_regs *regs)
>  {
> -       if (user_mode(regs)) {
> -               force_sig_fault(SIGTRAP, TRAP_BRKPT,
> -                               (void __user *)(regs->sepc));
> -               return;
> -       }
> -#ifdef CONFIG_GENERIC_BUG
> -       {
> -               enum bug_trap_type type;
> -
> -               type = report_bug(regs->sepc, regs);
> -               if (type == BUG_TRAP_TYPE_WARN) {
> -                       regs->sepc += get_break_insn_length(regs->sepc);
> -                       return;
> -               }
> -       }
> -#endif /* CONFIG_GENERIC_BUG */
> -
> -       die(regs, "Kernel BUG");
> +       if (user_mode(regs))
> +               force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->sepc);
> +       else if (report_bug(regs->sepc, regs) == BUG_TRAP_TYPE_WARN)
> +               regs->sepc += get_break_insn_length(regs->sepc);
> +       else
> +               die(regs, "Kernel BUG");
>  }
>
>  #ifdef CONFIG_GENERIC_BUG
> --
> 2.20.1
>
>
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv

LGTM.

Reviewed-by: Anup Patel <anup@...infault.org>

Regards,
Anup

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