powerpc: Never giveup a reclaimed thread when enabling kernel {fp, altivec, vsx}

[cascardo/linux.git] / arch / powerpc / kernel / process.c

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 34ee5f2..45b6ea0 100644 (file)
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -205,12 +205,23 @@ EXPORT_SYMBOL_GPL(flush_fp_to_thread);
 
 void enable_kernel_fp(void)
 {
+       unsigned long cpumsr;
+
        WARN_ON(preemptible());
 
-       msr_check_and_set(MSR_FP);
+       cpumsr = msr_check_and_set(MSR_FP);
 
        if (current->thread.regs && (current->thread.regs->msr & MSR_FP)) {
                check_if_tm_restore_required(current);
+               /*
+                * If a thread has already been reclaimed then the
+                * checkpointed registers are on the CPU but have definitely
+                * been saved by the reclaim code. Don't need to and *cannot*
+                * giveup as this would save  to the 'live' structure not the
+                * checkpointed structure.
+                */
+               if(!msr_tm_active(cpumsr) && msr_tm_active(current->thread.regs->msr))
+                       return;
                __giveup_fpu(current);
        }
 }
@@ -257,12 +268,23 @@ EXPORT_SYMBOL(giveup_altivec);
 
 void enable_kernel_altivec(void)
 {
+       unsigned long cpumsr;
+
        WARN_ON(preemptible());
 
-       msr_check_and_set(MSR_VEC);
+       cpumsr = msr_check_and_set(MSR_VEC);
 
        if (current->thread.regs && (current->thread.regs->msr & MSR_VEC)) {
                check_if_tm_restore_required(current);
+               /*
+                * If a thread has already been reclaimed then the
+                * checkpointed registers are on the CPU but have definitely
+                * been saved by the reclaim code. Don't need to and *cannot*
+                * giveup as this would save  to the 'live' structure not the
+                * checkpointed structure.
+                */
+               if(!msr_tm_active(cpumsr) && msr_tm_active(current->thread.regs->msr))
+                       return;
                __giveup_altivec(current);
        }
 }
@@ -331,12 +353,23 @@ static void save_vsx(struct task_struct *tsk)
 
 void enable_kernel_vsx(void)
 {
+       unsigned long cpumsr;
+
        WARN_ON(preemptible());
 
-       msr_check_and_set(MSR_FP|MSR_VEC|MSR_VSX);
+       cpumsr = msr_check_and_set(MSR_FP|MSR_VEC|MSR_VSX);
 
        if (current->thread.regs && (current->thread.regs->msr & MSR_VSX)) {
                check_if_tm_restore_required(current);
+               /*
+                * If a thread has already been reclaimed then the
+                * checkpointed registers are on the CPU but have definitely
+                * been saved by the reclaim code. Don't need to and *cannot*
+                * giveup as this would save  to the 'live' structure not the
+                * checkpointed structure.
+                */
+               if(!msr_tm_active(cpumsr) && msr_tm_active(current->thread.regs->msr))
+                       return;
                if (current->thread.regs->msr & MSR_FP)
                        __giveup_fpu(current);
                if (current->thread.regs->msr & MSR_VEC)