From: pinskia@gmail.com
To: Carlos O'Donell <carlos@redhat.com>
Cc: Will Newton <will.newton@linaro.org>,
"libc-ports@sourceware.org" <libc-ports@sourceware.org>,
"patches@linaro.org" <patches@linaro.org>
Subject: Re: [PATCH] ARM: Add pointer guard support.
Date: Wed, 25 Sep 2013 16:20:00 -0000 [thread overview]
Message-ID: <34DAC322-9D37-411A-8C55-86B604F5799D@gmail.com> (raw)
In-Reply-To: <52430AA4.70703@redhat.com>
> On Sep 25, 2013, at 9:09 AM, "Carlos O'Donell" <carlos@redhat.com> 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.
T
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] https://sourceware.org/ml/libc-ports/2013-08/msg00052.html
>
next prev parent 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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