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

This patch adds the ability to be able to save the VSX 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 and VEC registers
in the thread copy path to avoid a possibly pointless reload of VSX state.

Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h
index 9028822..17c8380 100644 (file)
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -56,14 +56,10 @@ static inline void __giveup_altivec(struct task_struct *t) { }
 #ifdef CONFIG_VSX
 extern void enable_kernel_vsx(void);
 extern void flush_vsx_to_thread(struct task_struct *);
-extern void giveup_vsx(struct task_struct *);
-extern void __giveup_vsx(struct task_struct *);
 static inline void disable_kernel_vsx(void)
 {
        msr_check_and_clear(MSR_FP|MSR_VEC|MSR_VSX);
 }
-#else
-static inline void __giveup_vsx(struct task_struct *t) { }
 #endif
 
 #ifdef CONFIG_SPE

diff --git a/arch/powerpc/kernel/ppc_ksyms.c b/arch/powerpc/kernel/ppc_ksyms.c
index 41e1607..ef7024d 100644 (file)
--- a/arch/powerpc/kernel/ppc_ksyms.c
+++ b/arch/powerpc/kernel/ppc_ksyms.c
@@ -28,10 +28,6 @@ EXPORT_SYMBOL(load_vr_state);
 EXPORT_SYMBOL(store_vr_state);
 #endif
 
-#ifdef CONFIG_VSX
-EXPORT_SYMBOL_GPL(__giveup_vsx);
-#endif
-
 #ifdef CONFIG_EPAPR_PARAVIRT
 EXPORT_SYMBOL(epapr_hypercall_start);
 #endif

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 14c09d2..d7a9df5 100644 (file)
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -280,19 +280,31 @@ static inline int restore_altivec(struct task_struct *tsk) { return 0; }
 #endif /* CONFIG_ALTIVEC */
 
 #ifdef CONFIG_VSX
-void giveup_vsx(struct task_struct *tsk)
+static void __giveup_vsx(struct task_struct *tsk)
 {
-       check_if_tm_restore_required(tsk);
-
-       msr_check_and_set(MSR_FP|MSR_VEC|MSR_VSX);
        if (tsk->thread.regs->msr & MSR_FP)
                __giveup_fpu(tsk);
        if (tsk->thread.regs->msr & MSR_VEC)
                __giveup_altivec(tsk);
+       tsk->thread.regs->msr &= ~MSR_VSX;
+}
+
+static void giveup_vsx(struct task_struct *tsk)
+{
+       check_if_tm_restore_required(tsk);
+
+       msr_check_and_set(MSR_FP|MSR_VEC|MSR_VSX);
        __giveup_vsx(tsk);
        msr_check_and_clear(MSR_FP|MSR_VEC|MSR_VSX);
 }
-EXPORT_SYMBOL(giveup_vsx);
+
+static void save_vsx(struct task_struct *tsk)
+{
+       if (tsk->thread.regs->msr & MSR_FP)
+               save_fpu(tsk);
+       if (tsk->thread.regs->msr & MSR_VEC)
+               save_altivec(tsk);
+}
 
 void enable_kernel_vsx(void)
 {
@@ -335,6 +347,7 @@ static int restore_vsx(struct task_struct *tsk)
 }
 #else
 static inline int restore_vsx(struct task_struct *tsk) { return 0; }
+static inline void save_vsx(struct task_struct *tsk) { }
 #endif /* CONFIG_VSX */
 
 #ifdef CONFIG_SPE
@@ -478,14 +491,19 @@ void save_all(struct task_struct *tsk)
 
        msr_check_and_set(msr_all_available);
 
-       if (usermsr & MSR_FP)
-               save_fpu(tsk);
-
-       if (usermsr & MSR_VEC)
-               save_altivec(tsk);
+       /*
+        * Saving the way the register space is in hardware, save_vsx boils
+        * down to a save_fpu() and save_altivec()
+        */
+       if (usermsr & MSR_VSX) {
+               save_vsx(tsk);
+       } else {
+               if (usermsr & MSR_FP)
+                       save_fpu(tsk);
 
-       if (usermsr & MSR_VSX)
-               __giveup_vsx(tsk);
+               if (usermsr & MSR_VEC)
+                       save_altivec(tsk);
+       }
 
        if (usermsr & MSR_SPE)
                __giveup_spe(tsk);

diff --git a/arch/powerpc/kernel/vector.S b/arch/powerpc/kernel/vector.S
index 51b0c17..1c2e7a3 100644 (file)
--- a/arch/powerpc/kernel/vector.S
+++ b/arch/powerpc/kernel/vector.S
@@ -151,23 +151,6 @@ _GLOBAL(load_up_vsx)
        std     r12,_MSR(r1)
        b       fast_exception_return
 
-/*
- * __giveup_vsx(tsk)
- * Disable VSX for the task given as the argument.
- * Does NOT save vsx registers.
- */
-_GLOBAL(__giveup_vsx)
-       addi    r3,r3,THREAD            /* want THREAD of task */
-       ld      r5,PT_REGS(r3)
-       cmpdi   0,r5,0
-       beq     1f
-       ld      r4,_MSR-STACK_FRAME_OVERHEAD(r5)
-       lis     r3,MSR_VSX@h
-       andc    r4,r4,r3                /* disable VSX for previous task */
-       std     r4,_MSR-STACK_FRAME_OVERHEAD(r5)
-1:
-       blr
-
 #endif /* CONFIG_VSX */