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From: Kees Cook <keescook@chromium.org>
Date: Thu, 10 Nov 2016 13:04:20 -0800
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Subject: [kernel-hardening] Re: [RFC v4 PATCH 12/13] x86: implementation for HARDENED_ATOMIC
To: Peter Zijlstra <peterz@infradead.org>
Cc: Elena Reshetova <elena.reshetova@intel.com>, "kernel-hardening@lists.openwall.com" <kernel-hardening@lists.openwall.com>, Arnd Bergmann <arnd@arndb.de>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <h.peter.anvin@intel.com>, Will Deacon <will.deacon@arm.com>, Hans Liljestrand <ishkamiel@gmail.com>, David Windsor <dwindsor@gmail.com>
List-ID: <kernel-hardening.lists.openwall.com>

On Thu, Nov 10, 2016 at 12:40 PM, Peter Zijlstra <peterz@infradead.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