From: David Laight <David.Laight@ACULAB.COM>
To: "'Andy Lutomirski'" <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Jarkko Nikula <jarkko.nikula@linux.intel.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
"Linus Torvalds" <torvalds@linux-foundation.org>,
Borislav Petkov <bp@alien8.de>
Subject: RE: [PATCH] x86/entry/64: Fix native_load_gs_index() SWAPGS handling with IRQ state tracing enabled
Date: Wed, 29 Nov 2017 16:51:20 +0000 [thread overview]
Message-ID: <c3d2884bce244b0fa286cc5d1c07e23e@AcuMS.aculab.com> (raw)
In-Reply-To: <CALCETrWndxkJebKbxdCUVpa0_CkW9QdaMbE-d5M=XEw_JFG3YQ@mail.gmail.com>
From: Andy Lutomirski
> Sent: 29 November 2017 16:23
> > I can't remember what happens when swapgs itself faults.
...
> SWAPGS never faults.
Ah yes, I remember, it only restores the offset.
For 32bit processes you need to do a 'pop %gs' to recover
the segment register itself - and that can fault.
SWAPGS is a PITA. The hardware designers should have tried to write
all the interrupt handling code.
David
next prev parent reply other threads:[~2017-11-29 16:51 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-28 14:35 Suspend-to-ram/resume regression with commit ca37e57bbe0c Jarkko Nikula
2017-11-29 7:09 ` [PATCH] x86/entry/64: Fix native_load_gs_index() SWAPGS handling with IRQ state tracing enabled Ingo Molnar
2017-11-29 9:25 ` Jarkko Nikula
2017-11-29 9:28 ` Thomas Gleixner
2017-11-29 12:39 ` Jarkko Nikula
2017-11-29 12:47 ` Peter Zijlstra
2017-11-29 14:33 ` Andy Lutomirski
2017-11-29 14:56 ` David Laight
2017-11-29 16:22 ` Andy Lutomirski
2017-11-29 16:51 ` David Laight [this message]
2017-11-29 20:48 ` Linus Torvalds
2017-11-29 16:51 ` Andy Lutomirski
2017-11-29 17:57 ` Andy Lutomirski
2017-11-29 18:08 ` Peter Zijlstra
2017-11-29 18:12 ` Andy Lutomirski
2017-11-29 20:58 ` Linus Torvalds
2017-11-29 21:25 ` Andy Lutomirski
2017-11-29 21:41 ` Andy Lutomirski
2017-11-29 21:57 ` Andy Lutomirski
2017-11-30 8:42 ` Jarkko Nikula
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