powerpc: Document register clobbering in EXCEPTION_COMMON()

Signed-off-by: Michael Ellerman <[email protected]>
Signed-off-by: Benjamin Herrenschmidt <[email protected]>

diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h
index 8f35cd7d59cc6565f07bb46fd1cb392a8794c47e..066c15cd2837c09ee9233532f3a9929595e9e3df 100644 (file)
--- a/arch/powerpc/include/asm/exception-64s.h
+++ b/arch/powerpc/include/asm/exception-64s.h
@@ -532,6 +532,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_CTRL)
        .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;                                           \