Commit e9625917 authored Aug 24, 2012 by Suresh Siddha Committed by H. Peter Anvin Sep 18, 2012

x86, fpu: drop_fpu() before restoring new state from sigframe



No need to save the state with unlazy_fpu(), that is about to get overwritten
by the state from the signal frame. Instead use drop_fpu() and continue
to restore the new state.

Also fold the stop_fpu_preload() into drop_fpu().

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1345842782-24175-2-git-send-email-suresh.b.siddha@intel.com


Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

parent 72a671ce

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

+1 −6

Original line number	Original line	Diff line number	Diff line
	@@ -448,17 +448,12 @@ static inline void save_init_fpu(struct task_struct *tsk)
	preempt_enable();		preempt_enable();
	}		}

	static inline void stop_fpu_preload(struct task_struct *tsk)
	{
	tsk->fpu_counter = 0;
	}

	static inline void drop_fpu(struct task_struct *tsk)		static inline void drop_fpu(struct task_struct *tsk)
	{		{
	/*		/*
	* Forget coprocessor state..		* Forget coprocessor state..
	*/		*/
	stop_fpu_preload(tsk);		tsk->fpu_counter = 0;
	preempt_disable();		preempt_disable();
	__drop_fpu(tsk);		__drop_fpu(tsk);
	preempt_enable();		preempt_enable();

arch/x86/kernel/xsave.c

+3 −5

Original line number	Original line	Diff line number	Diff line
	@@ -382,16 +382,14 @@ int __restore_xstate_sig(void __user buf, void __user buf_fx, int size)
	struct xsave_struct *xsave = &tsk->thread.fpu.state->xsave;		struct xsave_struct *xsave = &tsk->thread.fpu.state->xsave;
	struct user_i387_ia32_struct env;		struct user_i387_ia32_struct env;

	stop_fpu_preload(tsk);		drop_fpu(tsk);
	unlazy_fpu(tsk);

	if (__copy_from_user(xsave, buf_fx, state_size) \|\|		if (__copy_from_user(xsave, buf_fx, state_size) \|\|
	__copy_from_user(&env, buf, sizeof(env))) {		__copy_from_user(&env, buf, sizeof(env)))
	drop_fpu(tsk);
	return -1;		return -1;
	}

	sanitize_restored_xstate(tsk, &env, xstate_bv, fx_only);		sanitize_restored_xstate(tsk, &env, xstate_bv, fx_only);
			set_used_math();
	} else {		} else {
	/*		/*
	* For 64-bit frames and 32-bit fsave frames, restore the user		* For 64-bit frames and 32-bit fsave frames, restore the user