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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: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
hifive-unleashed-5.1
Cyril Bur 2016-02-29 17:53:50 +11:00 committed by Michael Ellerman
parent 8792468da5
commit 6f515d842e
3 changed files with 17 additions and 22 deletions
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3
arch/powerpc/include/asm/switch_to.h
View File

@ -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

12
arch/powerpc/kernel/process.c
View File

@ -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);

24
arch/powerpc/kernel/vector.S
View File

@ -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