From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: linux-kernel@vger.kernel.org
Cc: x86@kernel.org, "Andy Lutomirski" <luto@kernel.org>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
kvm@vger.kernel.org, "Jason A. Donenfeld" <Jason@zx2c4.com>,
"Rik van Riel" <riel@surriel.com>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"Sebastian Andrzej Siewior" <bigeasy@linutronix.de>
Subject: [PATCH 03/22] x86/fpu: Remove preempt_disable() in fpu__clear()
Date: Wed, 9 Jan 2019 12:47:25 +0100 [thread overview]
Message-ID: <20190109114744.10936-4-bigeasy@linutronix.de> (raw)
In-Reply-To: <20190109114744.10936-1-bigeasy@linutronix.de>
The preempt_disable() section was introduced in commit
a10b6a16cdad8 ("x86/fpu: Make the fpu state change in fpu__clear() scheduler-atomic")
and it was said to be temporary.
fpu__initialize() initializes the FPU struct to its "init" value and
then sets ->initialized to 1. The last part is the important one.
The content of the `state' does not matter because it gets set via
copy_init_fpstate_to_fpregs().
A preemption here has little meaning because the register will always be
set to the same content after copy_init_fpstate_to_fpregs(). A softirq
with a kernel_fpu_begin() could also force to save FPU's register after
fpu__initialize() without changing the outcome here.
Remove the preempt_disable() section in fpu__clear(), preemption here
does not hurt.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
arch/x86/kernel/fpu/core.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 1d3ae7988f7f2..1940319268aef 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -366,11 +366,9 @@ void fpu__clear(struct fpu *fpu)
* Make sure fpstate is cleared and initialized.
*/
if (static_cpu_has(X86_FEATURE_FPU)) {
- preempt_disable();
fpu__initialize(fpu);
user_fpu_begin();
copy_init_fpstate_to_fpregs();
- preempt_enable();
}
}
--
2.20.1
next prev parent reply other threads:[~2019-01-09 11:51 UTC|newest]
Thread overview: 91+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-09 11:47 [PATCH v6] x86: load FPU registers on return to userland Sebastian Andrzej Siewior
2019-01-09 11:47 ` [PATCH 01/22] x86/fpu: Remove fpu->initialized usage in __fpu__restore_sig() Sebastian Andrzej Siewior
2019-01-14 16:24 ` Borislav Petkov
2019-02-05 10:08 ` Sebastian Andrzej Siewior
2019-01-09 11:47 ` [PATCH 02/22] x86/fpu: Remove fpu__restore() Sebastian Andrzej Siewior
2019-01-09 11:47 ` Sebastian Andrzej Siewior [this message]
2019-01-14 18:55 ` [PATCH 03/22] x86/fpu: Remove preempt_disable() in fpu__clear() Borislav Petkov
2019-01-09 11:47 ` [PATCH 04/22] x86/fpu: Always init the `state' " Sebastian Andrzej Siewior
2019-01-14 19:32 ` Borislav Petkov
2019-01-09 11:47 ` [PATCH 05/22] x86/fpu: Remove fpu->initialized usage in copy_fpstate_to_sigframe() Sebastian Andrzej Siewior
2019-01-16 19:36 ` Borislav Petkov
2019-01-16 22:40 ` Sebastian Andrzej Siewior
2019-01-17 12:22 ` Borislav Petkov
2019-01-18 21:14 ` Sebastian Andrzej Siewior
2019-01-18 21:17 ` Dave Hansen
2019-01-18 21:37 ` Sebastian Andrzej Siewior
2019-01-18 21:43 ` Dave Hansen
2019-01-21 11:21 ` Oleg Nesterov
2019-01-22 13:40 ` Borislav Petkov
2019-01-22 16:15 ` Oleg Nesterov
2019-01-22 17:00 ` Borislav Petkov
2019-02-05 11:34 ` Sebastian Andrzej Siewior
2019-02-05 11:17 ` Sebastian Andrzej Siewior
2019-02-26 16:38 ` Oleg Nesterov
2019-03-08 18:12 ` Sebastian Andrzej Siewior
2019-02-05 14:37 ` [PATCH 05/22 v2] " Sebastian Andrzej Siewior
2019-01-09 11:47 ` [PATCH 06/22] x86/fpu: Don't save fxregs for ia32 frames " Sebastian Andrzej Siewior
2019-01-24 11:17 ` Borislav Petkov
2019-02-05 16:43 ` [PATCH 06/22 v2] x86/fpu: Don't save fxregs for ia32 frames in Sebastian Andrzej Siewior
2019-01-09 11:47 ` [PATCH 07/22] x86/fpu: Remove fpu->initialized Sebastian Andrzej Siewior
2019-01-24 13:34 ` Borislav Petkov
2019-02-05 18:03 ` Sebastian Andrzej Siewior
2019-02-06 14:01 ` Borislav Petkov
2019-02-07 10:13 ` Sebastian Andrzej Siewior
2019-02-07 10:37 ` Borislav Petkov
2019-02-05 18:06 ` [PATCH 07/22 v2] " Sebastian Andrzej Siewior
2019-01-09 11:47 ` [PATCH 08/22] x86/fpu: Remove user_fpu_begin() Sebastian Andrzej Siewior
2019-01-25 15:18 ` Borislav Petkov
2019-02-05 18:16 ` Sebastian Andrzej Siewior
2019-01-09 11:47 ` [PATCH 09/22] x86/fpu: Add (__)make_fpregs_active helpers Sebastian Andrzej Siewior
2019-01-28 18:23 ` Borislav Petkov
2019-02-07 10:43 ` Sebastian Andrzej Siewior
2019-02-13 9:30 ` Borislav Petkov
2019-02-14 14:51 ` Sebastian Andrzej Siewior
2019-01-09 11:47 ` [PATCH 10/22] x86/fpu: Make __raw_xsave_addr() use feature number instead of mask Sebastian Andrzej Siewior
2019-01-28 18:30 ` Borislav Petkov
2019-01-09 11:47 ` [PATCH 11/22] x86/fpu: Make get_xsave_field_ptr() and get_xsave_addr() " Sebastian Andrzej Siewior
2019-01-28 18:49 ` Borislav Petkov
2019-02-07 11:13 ` Sebastian Andrzej Siewior
2019-02-13 9:31 ` Borislav Petkov
2019-01-09 11:47 ` [PATCH 12/22] x86/fpu: Only write PKRU if it is different from current Sebastian Andrzej Siewior
2019-01-23 18:09 ` Dave Hansen
2019-02-07 11:27 ` Sebastian Andrzej Siewior
2019-01-09 11:47 ` [PATCH 13/22] x86/pkeys: Don't check if PKRU is zero before writting it Sebastian Andrzej Siewior
2019-01-09 11:47 ` [PATCH 14/22] x86/fpu: Eager switch PKRU state Sebastian Andrzej Siewior
2019-01-09 11:47 ` [PATCH 15/22] x86/entry: Add TIF_NEED_FPU_LOAD Sebastian Andrzej Siewior
2019-01-30 11:55 ` Borislav Petkov
2019-02-07 11:49 ` Sebastian Andrzej Siewior
2019-02-13 9:35 ` Borislav Petkov
2019-02-14 15:28 ` Sebastian Andrzej Siewior
2019-01-09 11:47 ` [PATCH 16/22] x86/fpu: Always store the registers in copy_fpstate_to_sigframe() Sebastian Andrzej Siewior
2019-01-30 11:43 ` Borislav Petkov
2019-02-07 13:28 ` Sebastian Andrzej Siewior
2019-01-09 11:47 ` [PATCH 17/22] x86/fpu: Prepare copy_fpstate_to_sigframe() for TIF_NEED_FPU_LOAD Sebastian Andrzej Siewior
2019-01-30 11:56 ` Borislav Petkov
2019-01-30 12:28 ` Sebastian Andrzej Siewior
2019-01-30 12:53 ` Borislav Petkov
2019-02-07 14:10 ` Sebastian Andrzej Siewior
2019-01-09 11:47 ` [PATCH 18/22] x86/fpu: Update xstate's PKRU value on write_pkru() Sebastian Andrzej Siewior
2019-01-23 17:28 ` Dave Hansen
2019-01-09 11:47 ` [PATCH 19/22] x86/fpu: Inline copy_user_to_fpregs_zeroing() Sebastian Andrzej Siewior
2019-01-09 11:47 ` [PATCH 20/22] x86/fpu: Let __fpu__restore_sig() restore the !32bit+fxsr frame from kernel memory Sebastian Andrzej Siewior
2019-01-30 21:29 ` Borislav Petkov
2019-01-09 11:47 ` [PATCH 21/22] x86/fpu: Merge the two code paths in __fpu__restore_sig() Sebastian Andrzej Siewior
2019-01-09 11:47 ` [PATCH 22/22] x86/fpu: Defer FPU state load until return to userspace Sebastian Andrzej Siewior
2019-01-31 9:16 ` Borislav Petkov
2019-01-15 12:44 ` [PATCH v6] x86: load FPU registers on return to userland David Laight
2019-01-15 13:15 ` 'Sebastian Andrzej Siewior'
2019-01-15 14:33 ` David Laight
2019-01-15 19:46 ` Dave Hansen
2019-01-15 20:26 ` Andy Lutomirski
2019-01-15 20:54 ` Dave Hansen
2019-01-15 21:11 ` Andy Lutomirski
2019-01-16 10:31 ` David Laight
2019-01-16 10:18 ` David Laight
2019-01-30 11:35 ` Borislav Petkov
2019-01-30 12:06 ` Sebastian Andrzej Siewior
2019-01-30 12:27 ` Borislav Petkov
2019-02-08 13:12 ` Sebastian Andrzej Siewior
2019-02-13 15:54 ` Sebastian Andrzej Siewior
2019-02-21 11:49 [PATCH v7] " Sebastian Andrzej Siewior
2019-02-21 11:50 ` [PATCH 03/22] x86/fpu: Remove preempt_disable() in fpu__clear() Sebastian Andrzej Siewior
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