3 files changed, 19 insertions, 9 deletions

diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h
index 49a13e0ef234..294c2cedcf7a 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -15,6 +15,15 @@ extern struct task_struct *__switch_to(struct task_struct *,
 struct thread_struct;
 extern struct task_struct *_switch(struct thread_struct *prev,
                                    struct thread_struct *next);
+#ifdef CONFIG_PPC_BOOK3S_64
+static inline void save_tar(struct thread_struct *prev)
+{
+        if (cpu_has_feature(CPU_FTR_ARCH_207S))
+                prev->tar = mfspr(SPRN_TAR);
+}
+#else
+static inline void save_tar(struct thread_struct *prev) {}
+#endif
 
 extern void giveup_fpu(struct task_struct *);
 extern void load_up_fpu(void);
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 4674fe647ad7..2bd0b885b0fe 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -449,15 +449,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_DSCR)
 
 #ifdef CONFIG_PPC_BOOK3S_64
 BEGIN_FTR_SECTION
-        /*
-         * Back up the TAR across context switches.  Note that the TAR is not
-         * available for use in the kernel.  (To provide this, the TAR should
-         * be backed up/restored on exception entry/exit instead, and be in
-         * pt_regs.  FIXME, this should be in pt_regs anyway (for debug).)
-         */
-        mfspr   r0,SPRN_TAR
-        std     r0,THREAD_TAR(r3)
-
         /* Event based branch registers */
         mfspr   r0, SPRN_BESCR
         std     r0, THREAD_BESCR(r3)
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index c517dbe705fd..8083be20fe5e 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -600,6 +600,16 @@ struct task_struct *__switch_to(struct task_struct *prev,
         struct ppc64_tlb_batch *batch;
 #endif
 
+        /* Back up the TAR across context switches.
+         * Note that the TAR is not available for use in the kernel.  (To
+         * provide this, the TAR should be backed up/restored on exception
+         * entry/exit instead, and be in pt_regs.  FIXME, this should be in
+         * pt_regs anyway (for debug).)
+         * Save the TAR here before we do treclaim/trecheckpoint as these
+         * will change the TAR.
+         */
+        save_tar(&prev->thread);
+
         __switch_to_tm(prev);
 
 #ifdef CONFIG_SMP