linux-kernel - Re: [PATCHv8 14/17] x86/traps: Handle LASS thrown #SS

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Message-ID: <20250706102213.4ab365d7@pumpkin>
Date: Sun, 6 Jul 2025 10:22:13 +0100
From: David Laight <david.laight.linux@...il.com>
To: "H. Peter Anvin" <hpa@...or.com>
Cc: Sohil Mehta <sohil.mehta@...el.com>, "Kirill A. Shutemov"
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Subject: Re: [PATCHv8 14/17] x86/traps: Handle LASS thrown #SS

On Tue, 01 Jul 2025 19:06:10 -0700
"H. Peter Anvin" <hpa@...or.com> wrote:
...
> Note: for a FRED system, ERETU can generate #SS for a non-canonical user space
> RSP even in the absence of LASS, so if that is not currently handled that is an active bug.

Is that a fault in kernel space, or a fault in user space. 

Some of the traps for 'iret' happen after the transition to user space,
so the kernel doesn't have to handle them as special cases.
(I simplified (and fixed) one version of that code.)

	David