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Commit 6f515d84 authored by Cyril Bur's avatar Cyril Bur Committed by Michael Ellerman
Browse files

powerpc: Add the ability to save Altivec without giving it up 



This patch adds the ability to be able to save the VEC registers to the
thread struct without giving up (disabling the facility) next time the
process returns to userspace.

This patch builds on a previous optimisation for the FPU registers in the
thread copy path to avoid a possibly pointless reload of VEC state.

Signed-off-by: default avatarCyril Bur <cyrilbur@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 8792468d

arch/powerpc/include/asm/switch_to.h

+2 −1
Original line number Diff line number Diff line
@@ -43,12 +43,13 @@ static inline void flush_fp_to_thread(struct task_struct *t) { } 
extern void enable_kernel_altivec(void);

extern void flush_altivec_to_thread(struct task_struct *);

extern void giveup_altivec(struct task_struct *);

extern void __giveup_altivec(struct task_struct *);

extern void save_altivec(struct task_struct *);

static inline void disable_kernel_altivec(void)

{

	msr_check_and_clear(MSR_VEC);

}

#else

static inline void save_altivec(struct task_struct *t) { }

static inline void __giveup_altivec(struct task_struct *t) { }

#endif

arch/powerpc/kernel/process.c

+11 −1
Original line number Diff line number Diff line
@@ -213,6 +213,16 @@ static int restore_fp(struct task_struct *tsk) { return 0; } 
#ifdef CONFIG_ALTIVEC

#define loadvec(thr) ((thr).load_vec)



static void __giveup_altivec(struct task_struct *tsk)

{

	save_altivec(tsk);

	tsk->thread.regs->msr &= ~MSR_VEC;

#ifdef CONFIG_VSX

	if (cpu_has_feature(CPU_FTR_VSX))

		tsk->thread.regs->msr &= ~MSR_VSX;

#endif

}



void giveup_altivec(struct task_struct *tsk)

{

	check_if_tm_restore_required(tsk);
@@ -472,7 +482,7 @@ void save_all(struct task_struct *tsk) 
		save_fpu(tsk);



	if (usermsr & MSR_VEC)

		__giveup_altivec(tsk);

		save_altivec(tsk);



	if (usermsr & MSR_VSX)

		__giveup_vsx(tsk);

arch/powerpc/kernel/vector.S

+4 −20
Original line number Diff line number Diff line
@@ -106,36 +106,20 @@ _GLOBAL(load_up_altivec) 
	blr



/*

 * __giveup_altivec(tsk)

 * Disable VMX for the task given as the argument,

 * and save the vector registers in its thread_struct.

 * save_altivec(tsk)

 * Save the vector registers to its thread_struct

 */

_GLOBAL(__giveup_altivec)

_GLOBAL(save_altivec)

	addi	r3,r3,THREAD		/* want THREAD of task */

	PPC_LL	r7,THREAD_VRSAVEAREA(r3)

	PPC_LL	r5,PT_REGS(r3)

	PPC_LCMPI	0,r7,0

	bne	2f

	addi	r7,r3,THREAD_VRSTATE

2:	PPC_LCMPI	0,r5,0

	SAVE_32VRS(0,r4,r7)

2:	SAVE_32VRS(0,r4,r7)

	mfvscr	v0

	li	r4,VRSTATE_VSCR

	stvx	v0,r4,r7

	beq	1f

	PPC_LL	r4,_MSR-STACK_FRAME_OVERHEAD(r5)

#ifdef CONFIG_VSX

BEGIN_FTR_SECTION

	lis	r3,(MSR_VEC|MSR_VSX)@h

FTR_SECTION_ELSE

	lis	r3,MSR_VEC@h

ALT_FTR_SECTION_END_IFSET(CPU_FTR_VSX)

#else

	lis	r3,MSR_VEC@h

#endif

	andc	r4,r4,r3		/* disable FP for previous task */

	PPC_STL	r4,_MSR-STACK_FRAME_OVERHEAD(r5)

1:

	blr



#ifdef CONFIG_VSX