This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
Re: [RFA][PATCH] Stack clash protection 07/08 -- V4 (aarch64 bits)
- From: Jeff Law <law at redhat dot com>
- To: Wilco Dijkstra <Wilco dot Dijkstra at arm dot com>, Szabolcs Nagy <Szabolcs dot Nagy at arm dot com>, gcc-patches <gcc-patches at gcc dot gnu dot org>
- Cc: nd <nd at arm dot com>, Richard Earnshaw <Richard dot Earnshaw at arm dot com>, James Greenhalgh <James dot Greenhalgh at arm dot com>, Marcus Shawcroft <Marcus dot Shawcroft at arm dot com>
- Date: Mon, 27 Nov 2017 11:06:31 -0700
- Subject: Re: [RFA][PATCH] Stack clash protection 07/08 -- V4 (aarch64 bits)
- Authentication-results: sourceware.org; auth=none
- References: <3a6b1bdf-df0f-a512-fd2b-116d57702bc7@redhat.com> <DB6PR0801MB205342840273A485E44D16D783480@DB6PR0801MB2053.eurprd08.prod.outlook.com> <dc1452bb-69af-4c3a-b08c-dbb0a6f219da@redhat.com> <5A1C33D9.2050106@arm.com> <DB6PR0801MB2053EBF6B5BC32EB3D3D78DD83250@DB6PR0801MB2053.eurprd08.prod.outlook.com>
On 11/27/2017 10:33 AM, Wilco Dijkstra wrote:
> Szabolcs Nagy wrote:
>> On 28/10/17 05:08, Jeff Law wrote:
>>
>>> My hope would be that we simply don't ever use the params. They were
>>> done as much for *you* to experiment with as anything. I'd happy just
>>> delete them as there's essentially no guard rails to ensure their values
>>> are sane.
>>
>> so is there a consensus now that 64k guard size is what
>> gcc stack probing will assume?
>
> I think right now only AArch64 will use a 64KB probe size which is always
> enabled. It is best to hardcode this so it can't be changed or turned off,
> inadvertently or not...
>
>> if so i can propose a patch to glibc to actually have
>> that much guard by default in threads.. (i think it
>> makes sense on all 64bit targets to have bigger guard
>> and a consensus here would help making that change)
>
> Assuming a minimum 64KB thread guard size on 64-bit systems is unlikely to
> be controversial - the guard size in OS/GLIBC may be larger than the probe
> size used in GCC, so I suggest to propose a patch.
Agreed.
Jeff