From mboxrd@z Thu Jan  1 00:00:00 1970
From: Anshuman Khandual <anshuman.khandual@arm.com>
Date: Mon, 10 Jun 2019 04:48:34 +0000
Subject: Re: [RFC V3] mm: Generalize and rename notify_page_fault() as kprobe_page_fault()
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 <6e095842-0f7f-f428-653d-2b6e98fea6b3@intel.com>
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To: Dave Hansen <dave.hansen@intel.com>, linux-kernel@vger.kernel.org, linux-mm@kvack.org
Cc: Mark Rutland <mark.rutland@arm.com>, Michal Hocko <mhocko@suse.com>, linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>, Catalin Marinas <catalin.marinas@arm.com>, Dave Hansen <dave.hansen@linux.intel.com>, Will Deacon <will.deacon@arm.com>, Paul Mackerras <paulus@samba.org>, sparclinux@vger.kernel.org, linux-s390@vger.kernel.org, Yoshinori Sato <ysato@users.sourceforge.jp>, Michael Ellerman <mpe@ellerman.id.au>, x86@kernel.org, Russell King <linux@armlinux.org.uk>, Matthew Wilcox <willy@infradead.org>, Ingo Molnar <mingo@redhat.com>, Fenghua Yu <fenghua.yu@intel.com>, Stephen Rothwell <sfr@canb.auug.org.au>, Andrey Konovalov <andreyknvl@google.com>, Andy Lutomirski <luto@kernel.org>, Thomas Gleixner <tglx@linutronix.de>, linux-arm-kernel@lists.infradead.org, Christophe Leroy <christophe.leroy@c-s.fr>, Tony Luck <tony.luck@intel.com>, Heiko Carstens <heiko.carstens@de.ibm.com>, Martin Schwidefsky <schwidefsky@de.ibm.com>, Andrew Morton <akpm@linux-foundation.org>, linuxppc-dev@lists.ozlabs.org, "David S. Miller" <davem@davemloft.net>



On 06/07/2019 08:36 PM, Dave Hansen wrote:
> On 6/7/19 3:34 AM, Anshuman Khandual wrote:
>> +static nokprobe_inline bool kprobe_page_fault(struct pt_regs *regs,
>> +					      unsigned int trap)
>> +{
>> +	int ret = 0;
>> +
>> +	/*
>> +	 * To be potentially processing a kprobe fault and to be allowed
>> +	 * to call kprobe_running(), we have to be non-preemptible.
>> +	 */
>> +	if (kprobes_built_in() && !preemptible() && !user_mode(regs)) {
>> +		if (kprobe_running() && kprobe_fault_handler(regs, trap))
>> +			ret = 1;
>> +	}
>> +	return ret;
>> +}
> 
> Nits: Other that taking the nice, readable, x86 one and globbing it onto
> a single line, looks OK to me.  It does seem a _bit_ silly to go to the
> trouble of converting to 'bool' and then using 0/1 and an 'int'
> internally instead of true/false and a bool, though.  It's also not a

Changing to 'bool'...

> horrible thing to add a single line comment to this sucker to say:
> 
> /* returns true if kprobes handled the fault */
> 

Picking this in-code comment.

> In any case, and even if you don't clean any of this up:
> 
> Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
> 

Thanks !