From: Michael Ellerman <mpe@ellerman.id.au>
To: Anton Blanchard <anton@samba.org>,
benh@kernel.crashing.org, paulus@samba.org
Cc: linuxppc-dev@lists.ozlabs.org
Subject: Re: powerpc: Print instruction when logging unhandled exceptions
Date: Thu, 2 Oct 2014 17:14:46 +1000 (EST) [thread overview]
Message-ID: <20141002071446.66E37140183@ozlabs.org> (raw)
In-Reply-To: <1411621545-19310-1-git-send-email-anton@samba.org>
On Thu, 2014-25-09 at 05:05:45 UTC, Anton Blanchard wrote:
> It is often useful to see the instruction that caused an unhandled
> exception.
>
> diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
> index 0dc43f9..27e30c8 100644
> --- a/arch/powerpc/kernel/traps.c
> +++ b/arch/powerpc/kernel/traps.c
> @@ -252,9 +252,18 @@ void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr)
> }
>
> if (show_unhandled_signals && unhandled_signal(current, signr)) {
> + u32 __user *nia = (u32 __user *)regs->nip;
> + u32 insn = 0;
> +
> + pagefault_disable();
> + if (!access_ok(VERIFY_READ, nia, sizeof(*nia)) ||
> + __get_user_inatomic(insn, nia))
> + insn = 0xffffffffUL;
> + pagefault_enable();
Can you add a comment explaining that interesting construct?
Looks like we do something similar in the perf callchain code, though without
the access_ok() check?
cheers
prev parent reply other threads:[~2014-10-02 7:14 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-25 5:05 [PATCH] powerpc: Print instruction when logging unhandled exceptions Anton Blanchard
2014-10-02 7:14 ` Michael Ellerman [this message]
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