1 files changed, 20 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 44c733f4f829..9ae8451bbc83 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -448,6 +448,19 @@ END_FTR_SECTION_IFSET(CPU_FTR_DSCR)
         std     r23,_CCR(r1)
         std     r1,KSP(r3)      /* Set old stack pointer */
 
+#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)
+END_FTR_SECTION_IFSET(CPU_FTR_BCTAR)
+#endif
+
 #ifdef CONFIG_SMP
         /* We need a sync somewhere here to make sure that if the
          * previous task gets rescheduled on another CPU, it sees all
@@ -530,6 +543,13 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_1T_SEGMENT)
         mr      r1,r8           /* start using new stack pointer */
         std     r7,PACAKSAVE(r13)
 
+#ifdef CONFIG_PPC_BOOK3S_64
+BEGIN_FTR_SECTION
+        ld      r0,THREAD_TAR(r4)
+        mtspr   SPRN_TAR,r0
+END_FTR_SECTION_IFSET(CPU_FTR_BCTAR)
+#endif
+
 #ifdef CONFIG_ALTIVEC
 BEGIN_FTR_SECTION
         ld      r0,THREAD_VRSAVE(r4)