linux-kernel - Re: [PATCH] x86/shstk: Enable shadow stack for x32

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Message-ID: <ece5cc63-960d-4323-9128-5023b6d94dc0@intel.com>
Date: Fri, 22 Mar 2024 09:56:35 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: "H.J. Lu" <hjl.tools@...il.com>
Cc: linux-kernel@...r.kernel.org, x86@...nel.org,
 Rick P Edgecombe <rick.p.edgecombe@...el.com>
Subject: Re: [PATCH] x86/shstk: Enable shadow stack for x32

On 3/22/24 09:52, H.J. Lu wrote:
> On Fri, Mar 22, 2024 at 9:49 AM Dave Hansen <dave.hansen@...el.com> wrote:
>> On 3/15/24 07:04, H.J. Lu wrote:
>>> 1. Add shadow stack support to x32 signal.
>>> 2. Use the 64-bit map_shadow_stack syscall for x32.
>>> 3. Set up shadow stack for x32.
>>>
>>> Tested with shadow stack enabled x32 glibc on Intel Tiger Lake.
>> I don't think we should wire up code that's never going to get used in
>> practice.  I think I'd want to be sure of the existence of some
>> specific, real-world, long-term users of this before we add a new ABI
>> that we need to support forever.
>>
>> Are there real users?
> Were you talking about x32 users or x32 users with shadow stack?

x32 users who both want and will use shadow stacks.

It's been a long time since I've seen an x32 bug report.