[POWERPC] Defer processing of interrupts when the CPU wakes from sleep mode

This provides a way to defer processing of an interrupt that wakes the
processor out of sleep mode.  On 32-bit platforms that use an
interrupt to wake the processor, we have to have interrupts enabled in
hardware at the point where we go to sleep, otherwise the processor
will never wake up.  However, because interrupts are logically
disabled at this point, we don't want to process the interrupt
straight away.

This is handled by setting the _TLF_SLEEPING flag.  When we get an
interrupt and _TLF_SLEEPING is set, we firstly clear the MSR_EE
(external interrupt enable) bit in the saved MSR value, and secondly
we then return to the address in the link register, like we do for
_TLF_NAPPING, but without actually handling the interrupt.

Note that this is handled somewhat differently on powerbooks, so this
new code will only be used on non-Apple machines.

Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 3a05e9f93d4..888a364043a 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -147,6 +147,7 @@ transfer_to_handler:
         lwz     r12,TI_LOCAL_FLAGS(r9)
         mtcrf   0x01,r12
         bt-     31-TLF_NAPPING,4f
+        bt-     31-TLF_SLEEPING,7f
 #endif /* CONFIG_6xx */
         .globl transfer_to_handler_cont
 transfer_to_handler_cont:
@@ -164,6 +165,13 @@ transfer_to_handler_cont:
 4:      rlwinm  r12,r12,0,~_TLF_NAPPING
         stw     r12,TI_LOCAL_FLAGS(r9)
         b       power_save_6xx_restore
+
+7:      rlwinm  r12,r12,0,~_TLF_SLEEPING
+        stw     r12,TI_LOCAL_FLAGS(r9)
+        lwz     r9,_MSR(r11)            /* if sleeping, clear MSR.EE */
+        rlwinm  r9,r9,0,~MSR_EE
+        lwz     r12,_LINK(r11)          /* and return to address in LR */
+        b       fast_exception_return
 #endif
 
 /*