linux-kernel - Re: [PATCH v4 15/17] x86/traps: Fixup general protection faults caused by UMIP

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Message-ID: <20170223092724.GZ6515@twins.programming.kicks-ass.net>
Date:   Thu, 23 Feb 2017 10:27:24 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andy Lutomirski <luto@...nel.org>,
        Borislav Petkov <bp@...e.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Brian Gerst <brgerst@...il.com>,
        Chris Metcalf <cmetcalf@...lanox.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Liang Z Li <liang.z.li@...el.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Huang Rui <ray.huang@....com>, Jiri Slaby <jslaby@...e.cz>,
        Jonathan Corbet <corbet@....net>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Paul Gortmaker <paul.gortmaker@...driver.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Chen Yucong <slaoub@...il.com>,
        Alexandre Julliard <julliard@...ehq.org>,
        Stas Sergeev <stsp@...t.ru>, Fenghua Yu <fenghua.yu@...el.com>,
        "Ravi V. Shankar" <ravi.v.shankar@...el.com>,
        Shuah Khan <shuah@...nel.org>, linux-kernel@...r.kernel.org,
        x86@...nel.org, linux-msdos@...r.kernel.org, wine-devel@...ehq.org,
        Tony Luck <tony.luck@...el.com>
Subject: Re: [PATCH v4 15/17] x86/traps: Fixup general protection faults
 caused by UMIP

On Wed, Feb 22, 2017 at 10:37:04PM -0800, Ricardo Neri wrote:
> @@ -492,6 +493,9 @@ do_general_protection(struct pt_regs *regs, long error_code)
>  	RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
>  	cond_local_irq_enable(regs);
>  
> +	if (user_mode(regs) && (fixup_umip_exception(regs) == true))
> +		return;

I'm thinking

	if (user_mode(regs) && fixup_umip_exception(regs))
		return;

is actually easier to read.