From: Pekka Enberg <penberg@kernel.org>
To: Brian Gerst <brgerst@gmail.com>
Cc: hpa@zytor.com, x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 05/12] x86-64: Disable preemption when using TS_USEDFPU
Date: Sat, 04 Sep 2010 09:47:47 +0300 [thread overview]
Message-ID: <4C81EB93.4090304@kernel.org> (raw)
In-Reply-To: <1283563039-3466-6-git-send-email-brgerst@gmail.com>
On 4.9.2010 4.17, Brian Gerst wrote:
> Consolidates code and fixes the below race for 64-bit.
>
> commit 9fa2f37bfeb798728241cc4a19578ce6e4258f25
> Author: torvalds<torvalds>
> Date: Tue Sep 2 07:37:25 2003 +0000
>
> Be a lot more careful about TS_USEDFPU and preemption
>
> We had some races where we testecd (or set) TS_USEDFPU together
> with sequences that depended on the setting (like clearing or
> setting the TS flag in %cr0) and we could be preempted in between,
> which screws up the FPU state, since preemption will itself change
> USEDFPU and the TS flag.
>
> This makes it a lot more explicit: the "internal" low-level FPU
> functions ("__xxxx_fpu()") all require preemption to be disabled,
> and the exported "real" functions will make sure that is the case.
>
> One case - in __switch_to() - was switched to the non-preempt-safe
> internal version, since the scheduler itself has already disabled
> preemption.
>
> BKrev: 3f5448b5WRiQuyzAlbajs3qoQjSobw
>
> Signed-off-by: Brian Gerst<brgerst@gmail.com>
Acked-by: Pekka Enberg <penberg@kernel.org>
next prev parent reply other threads:[~2010-09-04 6:48 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-04 1:17 [PATCH 0/12] x86 FPU cleanups (v2) Brian Gerst
2010-09-04 1:17 ` [PATCH 01/12] x86: Use correct type for %cr4 Brian Gerst
2010-09-04 6:45 ` Pekka Enberg
2010-09-10 1:46 ` [tip:x86/fpu] " tip-bot for Brian Gerst
2010-09-04 1:17 ` [PATCH 02/12] x86: Merge fpu_init() Brian Gerst
2010-09-04 6:45 ` Pekka Enberg
2010-09-10 1:46 ` [tip:x86/fpu] x86, fpu: " tip-bot for Brian Gerst
2010-09-04 1:17 ` [PATCH 03/12] x86: Merge tolerant_fwait() Brian Gerst
2010-09-04 6:46 ` Pekka Enberg
2010-09-10 1:46 ` [tip:x86/fpu] x86, fpu: " tip-bot for Brian Gerst
2010-09-04 1:17 ` [PATCH 04/12] x86: Merge __save_init_fpu() Brian Gerst
2010-09-04 6:47 ` Pekka Enberg
2010-09-10 1:47 ` [tip:x86/fpu] x86, fpu: " tip-bot for Brian Gerst
2010-09-04 1:17 ` [PATCH 05/12] x86-64: Disable preemption when using TS_USEDFPU Brian Gerst
2010-09-04 6:47 ` Pekka Enberg [this message]
2010-09-10 1:47 ` [tip:x86/fpu] x86-64, fpu: " tip-bot for Brian Gerst
2010-09-04 1:17 ` [PATCH 06/12] x86-64: Fix %cs value in convert_from_fxsr() Brian Gerst
2010-09-04 6:51 ` Pekka Enberg
2010-09-10 1:47 ` [tip:x86/fpu] x86-64, fpu: " tip-bot for Brian Gerst
2010-09-04 1:17 ` [PATCH 07/12] x86-64: Simplify constraints for fxsave/fxtstor Brian Gerst
2010-09-04 6:48 ` Pekka Enberg
2010-09-09 21:22 ` H. Peter Anvin
2010-09-09 23:43 ` Brian Gerst
2010-09-10 1:48 ` [tip:x86/fpu] x86-64, fpu: " tip-bot for Brian Gerst
2010-09-04 1:17 ` [PATCH 08/12] x86-32: Remove math_emulate stub Brian Gerst
2010-09-04 6:48 ` Pekka Enberg
2010-09-10 1:48 ` [tip:x86/fpu] x86-32, fpu: " tip-bot for Brian Gerst
2010-09-04 1:17 ` [PATCH 09/12] x86: Remove unnecessary ifdefs from i387 code Brian Gerst
2010-09-04 6:49 ` Pekka Enberg
2010-09-10 1:48 ` [tip:x86/fpu] x86, fpu: " tip-bot for Brian Gerst
2010-09-04 1:17 ` [PATCH 10/12] x86: Remove PSHUFB_XMM5_* macros Brian Gerst
2010-09-04 6:49 ` Pekka Enberg
2010-09-10 1:49 ` [tip:x86/fpu] x86, fpu: " tip-bot for Brian Gerst
2010-09-04 1:17 ` [PATCH 11/12] x86-32: Rewrite fpu_save_init() Brian Gerst
2010-09-04 6:51 ` Pekka Enberg
2010-09-10 1:49 ` [tip:x86/fpu] x86-32, fpu: " tip-bot for Brian Gerst
2010-09-04 1:17 ` [PATCH 12/12] x86: Merge fpu_save_init() Brian Gerst
2010-09-04 6:51 ` Pekka Enberg
2010-09-10 1:50 ` [tip:x86/fpu] x86, fpu: " tip-bot for Brian Gerst
2010-09-04 6:45 ` [PATCH 0/12] x86 FPU cleanups (v2) Pekka Enberg
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