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To: Carlos O'Donell <>
Cc: Will Newton <>,
	"" <>,
	"" <>
Subject: Re: [PATCH] ARM: Add pointer guard support.
Date: Wed, 25 Sep 2013 16:20:00 -0000	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

> On Sep 25, 2013, at 9:09 AM, "Carlos O'Donell" <> wrote:
>> On 09/25/2013 05:06 AM, Will Newton wrote:
>> Add support for pointer mangling in glibc internal structures in C
>> and assembler code.
>> Tested on armv7 with hard and soft thread pointers.
> Have you measured the performance versus using the existing
> global variable? 
> TLS access on ARM is quite slow and it looks to me like it 
> may be faster to use the global variable. Keep in mind that
> the pointer guard and stack guard do not vary by thread.
> 32-bit ARM is currently using a global variable e.g.
> __pointer_chk_guard, all you need to do to make it work
> is adjust the definitions of PTR_MANGLE and PTR_DEMANGLE
> to reference the global symbol.
> This is the second proposal for ARM (first was [1] for
> AArch64) to support storing the a guard in the TCB, but
> nobody has responded yet to my question about performance.
I wonder the same question.  Why move to using to tcb in the first place.  The only answer I can figure out is that is what x86 does but that is not always the correct answer.

> Cheers,
> Carlos.
> [1]

  reply	other threads:[~2013-09-25 16:20 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-09-25  9:06 Will Newton
2013-09-25 16:09 ` Carlos O'Donell
2013-09-25 16:20   ` pinskia [this message]
2013-09-25 16:23   ` Will Newton
2013-09-25 16:25     ` Carlos O'Donell
2013-09-25 16:59     ` Andrew Haley
2013-09-25 19:32       ` Will Newton
2013-09-26 15:02 ` Carlos O'Donell

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