Linux-RISC-V Archive on lore.kernel.org
 help / color / Atom feed
From: Christoph Hellwig <hch@infradead.org>
To: Vincent Chen <vincent.chen@sifive.com>
Cc: linux-riscv@lists.infradead.org, palmer@sifive.com,
	linux-kernel@vger.kernel.org, aou@eecs.berkeley.edu,
	paul.walmsley@sifive.com
Subject: Re: [PATCH 4/4] riscv: remove the switch statement in do_trap_break()
Date: Fri, 27 Sep 2019 15:47:11 -0700
Message-ID: <20190927224711.GI4700@infradead.org> (raw)
In-Reply-To: <1569199517-5884-5-git-send-email-vincent.chen@sifive.com>

On Mon, Sep 23, 2019 at 08:45:17AM +0800, Vincent Chen wrote:
> To make the code more straightforward, replacing the switch statement
> with if statement.
> 
> Suggested-by: Paul Walmsley <paul.walmsley@sifive.com>
> Signed-off-by: Vincent Chen <vincent.chen@sifive.com>
> ---
>  arch/riscv/kernel/traps.c | 23 ++++++++++++-----------
>  1 file changed, 12 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
> index dd13bc90aeb6..1ac75f7d0bff 100644
> --- a/arch/riscv/kernel/traps.c
> +++ b/arch/riscv/kernel/traps.c
> @@ -124,23 +124,24 @@ static inline unsigned long get_break_insn_length(unsigned long pc)
>  
>  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");

I like where this is going, but I think this can be improved further
given that fact that report_bug has a nice stub for the
!CONFIG_GENERIC_BUG case.

How about:

	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");

_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

  reply index

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-23  0:45 [PATCH 0/4] riscv: correct the do_trap_break() Vincent Chen
2019-09-23  0:45 ` [PATCH 1/4] riscv: avoid kernel hangs when trapped in BUG() Vincent Chen
2019-09-27 22:25   ` Christoph Hellwig
2019-10-04 18:26   ` Paul Walmsley
2019-09-23  0:45 ` [PATCH 2/4] rsicv: avoid sending a SIGTRAP to a user thread trapped in WARN() Vincent Chen
2019-09-27 22:27   ` Christoph Hellwig
2019-09-27 22:56   ` Christoph Hellwig
2019-09-30  0:22     ` Vincent Chen
2019-10-04 18:26   ` Paul Walmsley
2019-09-23  0:45 ` [PATCH 3/4] riscv: Correct the handling of unexpected ebreak in do_trap_break() Vincent Chen
2019-09-27 22:43   ` Christoph Hellwig
2019-10-04 18:28   ` Paul Walmsley
2019-09-23  0:45 ` [PATCH 4/4] riscv: remove the switch statement " Vincent Chen
2019-09-27 22:47   ` Christoph Hellwig [this message]
2019-10-07 16:08     ` Paul Walmsley
2019-10-07 16:10       ` Christoph Hellwig
2019-10-07 16:30         ` Paul Walmsley
2019-10-08  0:14           ` Vincent Chen
2019-10-08 17:07             ` Paul Walmsley
2019-10-09 22:26         ` Paul Walmsley

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190927224711.GI4700@infradead.org \
    --to=hch@infradead.org \
    --cc=aou@eecs.berkeley.edu \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-riscv@lists.infradead.org \
    --cc=palmer@sifive.com \
    --cc=paul.walmsley@sifive.com \
    --cc=vincent.chen@sifive.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-RISC-V Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-riscv/0 linux-riscv/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-riscv linux-riscv/ https://lore.kernel.org/linux-riscv \
		linux-riscv@lists.infradead.org
	public-inbox-index linux-riscv

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.infradead.lists.linux-riscv


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git