linux-kernel - Re: [PATCHv7 13/16] x86/traps: Handle LASS thrown #SS

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Message-ID: <rzexbyswvsulo75edyffqgigtckiutwcx4jxbnwhynhm6nwc6l@tocxnm74fshi>
Date: Mon, 30 Jun 2025 12:50:02 +0300
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To: David Laight <david.laight.linux@...il.com>
Cc: Xin Li <xin@...or.com>, Andy Lutomirski <luto@...nel.org>, 
	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>, 
	Peter Zijlstra <peterz@...radead.org>, Ard Biesheuvel <ardb@...nel.org>, 
	"Paul E. McKenney" <paulmck@...nel.org>, Josh Poimboeuf <jpoimboe@...nel.org>, 
	Xiongwei Song <xiongwei.song@...driver.com>, Xin Li <xin3.li@...el.com>, 
	"Mike Rapoport (IBM)" <rppt@...nel.org>, Brijesh Singh <brijesh.singh@....com>, 
	Michael Roth <michael.roth@....com>, Tony Luck <tony.luck@...el.com>, 
	Alexey Kardashevskiy <aik@....com>, Alexander Shishkin <alexander.shishkin@...ux.intel.com>, 
	Jonathan Corbet <corbet@....net>, Sohil Mehta <sohil.mehta@...el.com>, 
	Ingo Molnar <mingo@...nel.org>, Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>, 
	Daniel Sneddon <daniel.sneddon@...ux.intel.com>, Kai Huang <kai.huang@...el.com>, 
	Sandipan Das <sandipan.das@....com>, Breno Leitao <leitao@...ian.org>, 
	Rick Edgecombe <rick.p.edgecombe@...el.com>, Alexei Starovoitov <ast@...nel.org>, 
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	Vegard Nossum <vegard.nossum@...cle.com>, Kees Cook <kees@...nel.org>, Eric Biggers <ebiggers@...gle.com>, 
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	Andrew Morton <akpm@...ux-foundation.org>, Luis Chamberlain <mcgrof@...nel.org>, 
	Yuntao Wang <ytcoode@...il.com>, Rasmus Villemoes <linux@...musvillemoes.dk>, 
	Christophe Leroy <christophe.leroy@...roup.eu>, Tejun Heo <tj@...nel.org>, Changbin Du <changbin.du@...wei.com>, 
	Huang Shijie <shijie@...amperecomputing.com>, Geert Uytterhoeven <geert+renesas@...der.be>, 
	Namhyung Kim <namhyung@...nel.org>, Arnaldo Carvalho de Melo <acme@...hat.com>, 
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org, 
	linux-mm@...ck.org
Subject: Re: [PATCHv7 13/16] x86/traps: Handle LASS thrown #SS

On Mon, Jun 30, 2025 at 09:30:27AM +0100, David Laight wrote:
> On Fri, 27 Jun 2025 13:31:44 +0300
> "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com> wrote:
> 
> > On Thu, Jun 26, 2025 at 10:57:47AM -0700, Xin Li wrote:
> > > On 6/25/2025 5:51 AM, Kirill A. Shutemov wrote:  
> > > > LASS throws a #GP for any violations except for stack register accesses,
> > > > in which case it throws a #SS instead. Handle this similarly to how other
> > > > LASS violations are handled.
> > > > 
> > > > In case of FRED, before handling #SS as LASS violation, kernel has to
> > > > check if there's a fixup for the exception. It can address #SS due to
> > > > invalid user context on ERETU[1]. See 5105e7687ad3 ("x86/fred: Fixup  
> > > 
> > > Forgot to put the link to [1]?  Maybe just remove "[1]"?  
> > 
> > I will add the link. It is important context.
> 
> Will the link still be valid in 5 years time when someone
> is looking back at the changes?

Re-reading the commit message I wrote, it is obvious that I reconsidered
putting the link and referenced commit instead.

I will drop [1];

-- 
  Kiryl Shutsemau / Kirill A. Shutemov