1 files changed, 25 insertions, 0 deletions

diff --git a/arch/sh/mm/Makefile_64 b/arch/sh/mm/Makefile_64
index 5ff83583593e..2731cf1c4e0a 100644
--- a/arch/sh/mm/Makefile_64
+++ b/arch/sh/mm/Makefile_64
@@ -17,3 +17,28 @@ obj-$(CONFIG_HUGETLB_PAGE)	+= hugetlbpage.o
 obj-$(CONFIG_NUMA)              += numa.o
 
 EXTRA_CFLAGS += -Werror
+
+# Special flags for fault_64.o.  This puts restrictions on the number of
+# caller-save registers that the compiler can target when building this file.
+# This is required because the code is called from a context in entry.S where
+# very few registers have been saved in the exception handler (for speed
+# reasons).
+# The caller save registers that have been saved and which can be used are
+# r2,r3,r4,r5 : argument passing
+# r15, r18 : SP and LINK
+# tr0-4 : allow all caller-save TR's.  The compiler seems to be able to make
+#         use of them, so it's probably beneficial to performance to save them
+#         and have them available for it.
+#
+# The resources not listed below are callee save, i.e. the compiler is free to
+# use any of them and will spill them to the stack itself.
+
+CFLAGS_fault_64.o += -ffixed-r7 \
+        -ffixed-r8 -ffixed-r9 -ffixed-r10 -ffixed-r11 -ffixed-r12 \
+        -ffixed-r13 -ffixed-r14 -ffixed-r16 -ffixed-r17 -ffixed-r19 \
+        -ffixed-r20 -ffixed-r21 -ffixed-r22 -ffixed-r23 \
+        -ffixed-r24 -ffixed-r25 -ffixed-r26 -ffixed-r27 \
+        -ffixed-r36 -ffixed-r37 -ffixed-r38 -ffixed-r39 -ffixed-r40 \
+        -ffixed-r41 -ffixed-r42 -ffixed-r43  \
+        -ffixed-r60 -ffixed-r61 -ffixed-r62 \
+        -fomit-frame-pointer