powerpc/irq: Run softirqs off the top of the irq stack

Nowadays, irq_exit() calls __do_softirq() pretty much directly
instead of calling do_softirq() which switches to the decicated
softirq stack.

This has lead to observed stack overflows on powerpc since we call
irq_enter() and irq_exit() outside of the scope that switches to
the irq stack.

This fixes it by moving the stack switching up a level, making
irq_enter() and irq_exit() run off the irq stack.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 4 insertions, 6 deletions

diff --git a/arch/powerpc/kernel/misc_64.S b/arch/powerpc/kernel/misc_64.S
index 971d7e78aff2..e59caf874d05 100644
--- a/arch/powerpc/kernel/misc_64.S
+++ b/arch/powerpc/kernel/misc_64.S
@@ -40,14 +40,12 @@ _GLOBAL(call_do_softirq)
         mtlr    r0
         blr
 
-_GLOBAL(call_handle_irq)
-        ld      r8,0(r6)
+_GLOBAL(call_do_irq)
         mflr    r0
         std     r0,16(r1)
-        mtctr   r8
-        stdu    r1,THREAD_SIZE-STACK_FRAME_OVERHEAD(r5)
-        mr      r1,r5
-        bctrl
+        stdu    r1,THREAD_SIZE-STACK_FRAME_OVERHEAD(r4)
+        mr      r1,r4
+        bl      .__do_irq
         ld      r1,0(r1)
         ld      r0,16(r1)
         mtlr    r0