From: "George Spelvin" <linux@horizon.com>
To: hpa@zytor.com, torvalds@linux-foundation.org
Cc: jack@suse.cz, linux-kernel@vger.kernel.org, linux@horizon.com,
maarten-baert@hotmail.com, mingo@kernel.org,
nate@thatsmathematics.com, priikone@iki.fi, sbsiddha@gmail.com,
stable@vger.kernel.org, tglx@linutronix.de, x86@kernel.org
Subject: Re: [PATCH] Make math_state_restore() save and restore the interrupt flag
Date: 1 Feb 2014 16:17:10 -0500 [thread overview]
Message-ID: <20140201211710.20281.qmail@science.horizon.com> (raw)
In-Reply-To: <CA+55aFxex2ymO3k_udRL=yT9xF5PtRx=O2O2vtL76PBUE0fNtg@mail.gmail.com>
> .. which *does* actually bring up something that might work, and might
> be a good idea: remove the "restore math state or set TS" from the
> normal kernel paths *entirely*, and move it to the "return to user
> space" phase.
This definitely seems much more sensible. For processors without
optimized context save/restore, the decision whether to restore eagerly
is best made once the kernel has decided what it's returning *to*.
>From an interrupt handler, there are now three cases:
1) FPU not in use, available for immediate use.
2) FPU in use by user-space; save to <location> before using.
3) FPU in use by kernel code; may not be used (unless we want
to add nested FPU state save hair).
next prev parent reply other threads:[~2014-02-01 21:17 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-30 22:01 [PATCH] Make math_state_restore() save and restore the interrupt flag Nate Eldredge
2014-01-30 22:24 ` Linus Torvalds
2014-01-31 7:33 ` Suresh Siddha
2014-02-01 19:27 ` Linus Torvalds
2014-02-01 19:35 ` H. Peter Anvin
2014-02-01 19:46 ` Linus Torvalds
2014-02-01 20:00 ` H. Peter Anvin
2014-02-01 20:16 ` Linus Torvalds
2014-02-01 20:16 ` H. Peter Anvin
2014-02-01 21:17 ` George Spelvin [this message]
2014-02-01 21:36 ` H. Peter Anvin
2014-02-01 21:36 ` H. Peter Anvin
2014-02-01 23:40 ` H. Peter Anvin
2014-02-02 0:17 ` Linus Torvalds
2014-02-02 1:19 ` George Spelvin
2014-02-02 1:25 ` H. Peter Anvin
2014-02-02 8:45 ` Pekka Riikonen
2014-02-02 1:06 ` Suresh Siddha
2014-02-02 1:26 ` H. Peter Anvin
2014-02-02 1:35 ` Suresh Siddha
2014-02-02 1:38 ` Linus Torvalds
2014-02-02 1:47 ` Suresh Siddha
2014-02-02 1:51 ` Linus Torvalds
2014-02-02 1:57 ` H. Peter Anvin
2014-02-02 2:05 ` Linus Torvalds
2014-02-02 2:12 ` H. Peter Anvin
2014-02-02 1:59 ` Suresh Siddha
2014-02-02 1:43 ` H. Peter Anvin
2014-02-02 1:47 ` Linus Torvalds
2014-02-02 7:19 ` Suresh Siddha
2014-02-02 19:15 ` Linus Torvalds
2014-02-03 6:56 ` Suresh Siddha
2014-02-03 18:20 ` Linus Torvalds
2014-02-04 6:03 ` Suresh Siddha
2014-02-06 5:26 ` Nate Eldredge
2014-02-06 5:34 ` George Spelvin
2014-02-13 15:45 ` Maarten Baert
2014-02-13 20:00 ` George Spelvin
2014-03-11 19:36 ` [tip:x86/urgent] x86, fpu: Check tsk_used_math() in kernel_fpu_end() for eager FPU tip-bot for Suresh Siddha
2014-02-27 23:44 ` [PATCH] Make math_state_restore() save and restore the interrupt flag H. Peter Anvin
2014-03-07 23:18 ` H. Peter Anvin
2014-03-08 6:18 ` Suresh Siddha
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