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Date: Thu, 10 Nov 2016 13:04:20 -0800
From: Kees Cook <keescook@...omium.org>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Elena Reshetova <elena.reshetova@...el.com>, 
	"kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>, Arnd Bergmann <arnd@...db.de>, 
	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, 
	"H. Peter Anvin" <h.peter.anvin@...el.com>, Will Deacon <will.deacon@....com>, 
	Hans Liljestrand <ishkamiel@...il.com>, David Windsor <dwindsor@...il.com>
Subject: Re: [RFC v4 PATCH 12/13] x86: implementation for HARDENED_ATOMIC

On Thu, Nov 10, 2016 at 12:40 PM, Peter Zijlstra <peterz@...radead.org> wrote:
> On Thu, Nov 10, 2016 at 10:24:47PM +0200, Elena Reshetova wrote:
>>  static __always_inline void atomic_add(int i, atomic_t *v)
>>  {
>> +     asm volatile(LOCK_PREFIX "addl %1,%0\n"
>> +
>> +#ifdef CONFIG_HARDENED_ATOMIC
>> +                  "jno 0f\n"
>> +                  LOCK_PREFIX "subl %1,%0\n"
>> +                  "int $4\n0:\n"
>> +                  _ASM_EXTABLE(0b, 0b)
>
>
> This is unreadable gunk.
>
>> +#endif
>> +
>>                    : "+m" (v->counter)
>>                    : "ir" (i));
>>  }

How would you suggest it be made readable? Or rather, what don't you
like about it?

-Kees

-- 
Kees Cook
Nexus Security

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