linux-kernel - [tip:x86/fpu] x86/fpu: Use restore_init_xstate() instead of math_state

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Date:	Mon, 23 Mar 2015 05:21:19 -0700
From:	tip-bot for Oleg Nesterov <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	tglx@...utronix.de, sbsiddha@...il.com, priikone@....fi,
	bp@...e.de, linux-kernel@...r.kernel.org, luto@...capital.net,
	quentin.casasnovas@...cle.com, riel@...hat.com, hpa@...or.com,
	oleg@...hat.com, torvalds@...ux-foundation.org,
	dave.hansen@...el.com, mingo@...nel.org, fenghua.yu@...el.com
Subject: [tip:x86/fpu] x86/fpu: Use restore_init_xstate()
  instead of math_state_restore() on kthread exec

Commit-ID:  9cb6ce823bbd1adbe15e30bd1435c84c2e271767
Gitweb:     http://git.kernel.org/tip/9cb6ce823bbd1adbe15e30bd1435c84c2e271767
Author:     Oleg Nesterov <oleg@...hat.com>
AuthorDate: Wed, 11 Mar 2015 18:34:49 +0100
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Mon, 23 Mar 2015 10:13:58 +0100

x86/fpu: Use restore_init_xstate() instead of math_state_restore() on kthread exec

Change flush_thread() to do user_fpu_begin() and restore_init_xstate()
instead of math_state_restore().

Note: "TODO: cleanup this horror" is still valid. We do not need
init_fpu() at all, we only need fpu_alloc() and memset(0). But this
needs other changes, in particular user_fpu_begin() should set
used_math().

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Dave Hansen <dave.hansen@...el.com>
Cc: Fenghua Yu <fenghua.yu@...el.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Pekka Riikonen <priikone@....fi>
Cc: Quentin Casasnovas <quentin.casasnovas@...cle.com>
Cc: Rik van Riel <riel@...hat.com>
Cc: Suresh Siddha <sbsiddha@...il.com>
Link: http://lkml.kernel.org/r/20150311173449.GE5032@redhat.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/process.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index dcaf4b0..6b05829 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -143,7 +143,8 @@ void flush_thread(void)
 		/* kthread execs. TODO: cleanup this horror. */
 		if (WARN_ON(init_fpu(current)))
 			force_sig(SIGKILL, current);
-		math_state_restore();
+		user_fpu_begin();
+		restore_init_xstate();
 	}
 }
 
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