When inserting SLB entries for EA above 512TB, we need to hard disable irq.
This will make sure we don't take a PMU interrupt that can possibly touch
user space address via a stack dump. To prevent this, we need to hard disable
the interrupt.
Also add a comment explaining why we don't need context synchronizing isync
with slbmte.
Fixes:
f384796c4 ("powerpc/mm: Add support for handling > 512TB address in SLB miss")
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
/*
* We are irq disabled, hence should be safe to access PACA.
*/
+ VM_WARN_ON(!irqs_disabled());
+
+ /*
+ * We can't take a PMU exception in the following code, so hard
+ * disable interrupts.
+ */
+ hard_irq_disable();
+
index = get_paca()->stab_rr;
/*
((unsigned long) ssize << SLB_VSID_SSIZE_SHIFT);
esid_data = mk_esid_data(ea, ssize, index);
+ /*
+ * No need for an isync before or after this slbmte. The exception
+ * we enter with and the rfid we exit with are context synchronizing.
+ * Also we only handle user segments here.
+ */
asm volatile("slbmte %0, %1" : : "r" (vsid_data), "r" (esid_data)
: "memory");