1 files changed, 33 insertions, 4 deletions

diff --git a/arch/powerpc/mm/slb.c b/arch/powerpc/mm/slb.c
index de0c8842415c..d3733912adb4 100644
--- a/arch/powerpc/mm/slb.c
+++ b/arch/powerpc/mm/slb.c
@@ -22,6 +22,8 @@
 #include <asm/paca.h>
 #include <asm/cputable.h>
 #include <asm/cacheflush.h>
+#include <asm/smp.h>
+#include <linux/compiler.h>
 
 #ifdef DEBUG
 #define DBG(fmt...) udbg_printf(fmt)
@@ -50,9 +52,32 @@ static inline unsigned long mk_vsid_data(unsigned long ea, unsigned long flags)
         return (get_kernel_vsid(ea) << SLB_VSID_SHIFT) | flags;
 }
 
-static inline void create_slbe(unsigned long ea, unsigned long flags,
-                               unsigned long entry)
+static inline void slb_shadow_update(unsigned long esid, unsigned long vsid,
+                                     unsigned long entry)
 {
+        /*
+         * Clear the ESID first so the entry is not valid while we are
+         * updating it.
+         */
+        get_slb_shadow()->save_area[entry].esid = 0;
+        barrier();
+        get_slb_shadow()->save_area[entry].vsid = vsid;
+        barrier();
+        get_slb_shadow()->save_area[entry].esid = esid;
+
+}
+
+static inline void create_shadowed_slbe(unsigned long ea, unsigned long flags,
+                                        unsigned long entry)
+{
+        /*
+         * Updating the shadow buffer before writing the SLB ensures
+         * we don't get a stale entry here if we get preempted by PHYP
+         * between these two statements.
+         */
+        slb_shadow_update(mk_esid_data(ea, entry), mk_vsid_data(ea, flags),
+                          entry);
+
         asm volatile("slbmte  %0,%1" :
                      : "r" (mk_vsid_data(ea, flags)),
                        "r" (mk_esid_data(ea, entry))
@@ -77,6 +102,10 @@ void slb_flush_and_rebolt(void)
         if ((ksp_esid_data & ESID_MASK) == PAGE_OFFSET)
                 ksp_esid_data &= ~SLB_ESID_V;
 
+        /* Only third entry (stack) may change here so only resave that */
+        slb_shadow_update(ksp_esid_data,
+                          mk_vsid_data(ksp_esid_data, lflags), 2);
+
         /* We need to do this all in asm, so we're sure we don't touch
          * the stack between the slbia and rebolting it. */
         asm volatile("isync\n"
@@ -209,9 +238,9 @@ void slb_initialize(void)
         asm volatile("isync":::"memory");
         asm volatile("slbmte  %0,%0"::"r" (0) : "memory");
         asm volatile("isync; slbia; isync":::"memory");
-        create_slbe(PAGE_OFFSET, lflags, 0);
+        create_shadowed_slbe(PAGE_OFFSET, lflags, 0);
 
-        create_slbe(VMALLOC_START, vflags, 1);
+        create_shadowed_slbe(VMALLOC_START, vflags, 1);
 
         /* We don't bolt the stack for the time being - we're in boot,
          * so the stack is in the bolted segment.  By the time it goes