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authorAnton Blanchard <anton@samba.org>2008-03-17 15:27:09 +1100
committerPaul Mackerras <paulus@samba.org>2008-03-20 10:14:55 +1100
commit44387e9ff25267c78a99229aca55ed750e9174c7 (patch)
tree84485e031d4a97898e3a80b5dc1c5a09b2e6e222
parentc2372eb9bcafdd149b26987a8c25bbed92fd2775 (diff)
[POWERPC] Fix PMU + soft interrupt disable bug
Since the PMU is an NMI now, it can come at any time we are only soft disabled. We must hard disable around the two places we allow the kernel stack SLB and r1 to go out of sync. Otherwise the PMU exception can force a kernel stack SLB into another slot, which can lead to it getting evicted, which can lead to a nasty unrecoverable SLB miss in the exception entry code. Signed-off-by: Anton Blanchard <anton@samba.org> Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Acked-by: Olof Johansson <olof@lixom.net> Signed-off-by: Paul Mackerras <paulus@samba.org>
-rw-r--r--arch/powerpc/kernel/process.c6
-rw-r--r--arch/powerpc/mm/slb.c6
2 files changed, 12 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 4846bf543a8..59311ec0d42 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -353,6 +353,12 @@ struct task_struct *__switch_to(struct task_struct *prev,
account_process_vtime(current);
calculate_steal_time();
+ /*
+ * We can't take a PMU exception inside _switch() since there is a
+ * window where the kernel stack SLB and the kernel stack are out
+ * of sync. Hard disable here.
+ */
+ hard_irq_disable();
last = _switch(old_thread, new_thread);
local_irq_restore(flags);
diff --git a/arch/powerpc/mm/slb.c b/arch/powerpc/mm/slb.c
index 47b06bad24a..906daeda59a 100644
--- a/arch/powerpc/mm/slb.c
+++ b/arch/powerpc/mm/slb.c
@@ -124,6 +124,12 @@ void slb_flush_and_rebolt(void)
ksp_vsid_data = get_slb_shadow()->save_area[2].vsid;
}
+ /*
+ * We can't take a PMU exception in the following code, so hard
+ * disable interrupts.
+ */
+ hard_irq_disable();
+
/* 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"