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-rw-r--r--arch/powerpc/mm/stab.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/arch/powerpc/mm/stab.c b/arch/powerpc/mm/stab.c
index 98cd1dc..ab5fb48 100644
--- 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;
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