Merge branch 'tracing-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[pandora-kernel.git] / arch / powerpc / mm / stab.c

diff --git a/arch/powerpc/mm/stab.c b/arch/powerpc/mm/stab.c
index 98cd1dc..ab5fb48 100644 (file)
--- a/arch/powerpc/mm/stab.c
+++ b/arch/powerpc/mm/stab.c
@@ -164,7 +164,7 @@ void switch_stab(struct task_struct *tsk, struct mm_struct *mm)
 {
        struct stab_entry *stab = (struct stab_entry *) get_paca()->stab_addr;
        struct stab_entry *ste;
-       unsigned long offset = __get_cpu_var(stab_cache_ptr);
+       unsigned long offset;
        unsigned long pc = KSTK_EIP(tsk);
        unsigned long stack = KSTK_ESP(tsk);
        unsigned long unmapped_base;
@@ -172,6 +172,15 @@ void switch_stab(struct task_struct *tsk, struct mm_struct *mm)
        /* Force previous translations to complete. DRENG */
        asm volatile("isync" : : : "memory");
 
+       /*
+        * We need interrupts hard-disabled here, not just soft-disabled,
+        * so that a PMU interrupt can't occur, which might try to access
+        * user memory (to get a stack trace) and possible cause an STAB miss
+        * which would update the stab_cache/stab_cache_ptr per-cpu variables.
+        */
+       hard_irq_disable();
+
+       offset = __get_cpu_var(stab_cache_ptr);
        if (offset <= NR_STAB_CACHE_ENTRIES) {
                int i;