linux-kernel - Re: [RFC] Rename various 'IA32' uses in arch/x86/ code

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Date:	Thu, 18 Jun 2015 23:13:18 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Brian Gerst <brgerst@...il.com>
Cc:	"H. Peter Anvin" <hpa@...or.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Borislav Petkov <bp@...en8.de>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Andy Lutomirski <luto@...capital.net>,
	linux-tip-commits@...r.kernel.org
Subject: Re: [RFC] Rename various 'IA32' uses in arch/x86/ code


* Brian Gerst <brgerst@...il.com> wrote:

> >> The original one wasn't really a misnomer, as it referred to the ia32 system 
> >> calls specifically, but this works too.
> >
> > It was a misnomer, because what are the 'ia32 system calls'? We have no Intel 
> > specific system calls!
> >
> > The term 'IA32' (Intel Architecture 32-bit) is a misnomer in many existing
> > arch/x86/ symbol, function and file names, and most of them should be renamed.
> >
> > Some common examples, with a suggested rename target:
> >
> >  stack_frame_ia32               -> stack_frame_compat
> >  IA32_RT_SIGFRAME_sigcontext    -> COMPAT_RT_SIGFRAME_sigcontext
> >  sigcontext_ia32                -> sigcontext_compat
> >  user_i387_ia32_struct          -> user_i387_compat_struct
> >  TIF_IA32                       -> TIF_COMPAT
> >
> > and here a few 'ia32' misnomers that should be addressed not via simple renames,
> > but via transformations to existing compat facilities:
> >
> >  CONFIG_IA32_EMULATION          -> partly eliminate, partly covert to CONFIG_COMPAT use
> 
> I think we still want a symbol for code that is exclusive to 32-bit 
> compatibility (like entry and signal code) to keep it separate from X32 which 
> also wants CONFIG_COMPAT.  If I get time this weekend I'll get the patchset to 
> do the separation updated to the tip branch.

Ok, so your goal is to allow the x32 ABI, but not 32-bit user-space?

I suppose that makes some sense, it might be a valid 'attack surface reduction' 
technique, while still allowing the x32 ABI.

But I'm not sure we should bother and complicate things: 32-bit compat isn't going 
away anytime soon, and most of CONFIG_COMPAT is needed for x32.

So maybe we could introduce CONFIG_X86_32_ABI=y or so, which would cover just the 
32-bit entry code and the signal frame compatibility layer?

Thanks,

	Ingo
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