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Commit 377ffbcc authored by Suresh Siddha's avatar Suresh Siddha Committed by H. Peter Anvin
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x86, fpu: remove unnecessary user_fpu_end() in save_xstate_sig() 



Few lines below we do drop_fpu() which is more safer. Remove the
unnecessary user_fpu_end() in save_xstate_sig(), which allows
the drop_fpu() to ignore any pending exceptions from the user-space
and drop the current fpu.

Signed-off-by: default avatarSuresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1345842782-24175-3-git-send-email-suresh.b.siddha@intel.com


Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent e9625917

arch/x86/include/asm/fpu-internal.h

+3 −14
Original line number Diff line number Diff line
@@ -412,22 +412,11 @@ static inline void __drop_fpu(struct task_struct *tsk) 
}



/*

 * The actual user_fpu_begin/end() functions

 * need to be preemption-safe.

 * Need to be preemption-safe.

 *

 * NOTE! user_fpu_end() must be used only after you

 * have saved the FP state, and user_fpu_begin() must

 * be used only immediately before restoring it.

 * These functions do not do any save/restore on

 * their own.

 * NOTE! user_fpu_begin() must be used only immediately before restoring

 * it. This function does not do any save/restore on their own.

 */

static inline void user_fpu_end(void)

{

	preempt_disable();

	__thread_fpu_end(current);

	preempt_enable();

}



static inline void user_fpu_begin(void)

{

	preempt_disable();

arch/x86/kernel/xsave.c

+0 −1
Original line number Diff line number Diff line
@@ -255,7 +255,6 @@ int save_xstate_sig(void __user *buf, void __user *buf_fx, int size) 
		/* Update the thread's fxstate to save the fsave header. */

		if (ia32_fxstate)

			fpu_fxsave(&tsk->thread.fpu);

		user_fpu_end();

	} else {

		sanitize_i387_state(tsk);

		if (__copy_to_user(buf_fx, xsave, xstate_size))