From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Thu, 20 Aug 2009 01:07:56 +0000 (+1000)
Subject: Merge commit 'paulus-perf/master' into next
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=4f0dbc2781b9dc457159b676289f874ab2dc3560;p=deliverable%2Flinux.git

Merge commit 'paulus-perf/master' into next
---

4f0dbc2781b9dc457159b676289f874ab2dc3560
diff --cc arch/powerpc/mm/slb.c
index 6bc8b4aeba5c,a685652effeb..07961c5c169e
--- a/arch/powerpc/mm/slb.c
+++ b/arch/powerpc/mm/slb.c
@@@ -184,8 -191,16 +191,16 @@@ void switch_slb(struct task_struct *tsk
  	unsigned long slbie_data = 0;
  	unsigned long pc = KSTK_EIP(tsk);
  	unsigned long stack = KSTK_ESP(tsk);
 -	unsigned long unmapped_base;
 +	unsigned long exec_base;
  
+ 	/*
+ 	 * 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 SLB miss
+ 	 * which would update the slb_cache/slb_cache_ptr fields in the PACA.
+ 	 */
+ 	hard_irq_disable();
+ 	offset = get_paca()->slb_cache_ptr;
  	if (!cpu_has_feature(CPU_FTR_NO_SLBIE_B) &&
  	    offset <= SLB_CACHE_ENTRIES) {
  		int i;