linux-kernel - [PATCH] x86, xsave: fix non-lazy allocation of the xsave area

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Date:	Wed, 13 Apr 2011 12:58:21 +0200
From:	Hans Rosenfeld <hans.rosenfeld@....com>
To:	<hpa@...or.com>, <mingo@...e.hu>
CC:	<brgerst@...il.com>, <tglx@...utronix.de>,
	<suresh.b.siddha@...el.com>, <eranian@...gle.com>,
	<robert.richter@....com>, <Andreas.Herrmann3@....com>,
	<x86@...nel.org>, <linux-kernel@...r.kernel.org>,
	Hans Rosenfeld <hans.rosenfeld@....com>
Subject: [PATCH] x86, xsave: fix non-lazy allocation of the xsave area

A single static xsave area just for init is not enough, since there are
more user processes that are directly executed by kernel threads. Use
fpu_alloc(), and SIGKILL the process if that fails.

Signed-off-by: Hans Rosenfeld <hans.rosenfeld@....com>
---
 arch/x86/include/asm/i387.h |    9 +++------
 1 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h
index 989c0ac..833b6f1 100644
--- a/arch/x86/include/asm/i387.h
+++ b/arch/x86/include/asm/i387.h
@@ -329,15 +329,12 @@ static inline void fpu_copy(struct fpu *dst, struct fpu *src)
 }
 
 extern void fpu_finit(struct fpu *fpu);
-static union thread_xstate __init_xstate, *init_xstate = &__init_xstate;
 
 static inline void fpu_clear(struct fpu *fpu)
 {
-	if (!fpu_allocated(fpu)) {
-		BUG_ON(init_xstate == NULL);
-		fpu->state = init_xstate;
-		init_xstate = NULL;
-	}
+	if (!fpu_allocated(fpu) && fpu_alloc(fpu))
+		do_group_exit(SIGKILL);
+
 	memset(fpu->state, 0, xstate_size);
 	fpu_finit(fpu);
 	set_used_math();
-- 
1.5.6.5


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