powerpc: Document register clobbering in EXCEPTION_COMMON()
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h
index 8f35cd7..066c15c 100644
--- a/arch/powerpc/include/asm/exception-64s.h
+++ b/arch/powerpc/include/asm/exception-64s.h
@@ -532,6 +532,7 @@
.globl label##_common; \
label##_common: \
EXCEPTION_PROLOG_COMMON(trap, PACA_EXGEN); \
+ /* Volatile regs are potentially clobbered here */ \
additions; \
addi r3,r1,STACK_FRAME_OVERHEAD; \
bl hdlr; \