ARC: Fix linking errors with CONFIG_MODULE + CONFIG_CC_OPTIMIZE_FOR_SIZE
At -Os, ARC gcc generates millicode thunk for function prologue/epilogue,
which are served by libgcc.
Modules historically are NOT linked with libgcc to avoid code bloat, reducing
runtime relocation fixups etc. I even once tried doing that but got lost
in makefile intricacies.
This means modules at -Os don't get the millicode thunks, causing build
failures below:
| MODPOST 5 modules
| ERROR: "__ld_r13_to_r18" [crypto/sha256_generic.ko] undefined!
| ERROR: "__ld_r13_to_r18_ret" [crypto/sha256_generic.ko] undefined!
| ERROR: "__st_r13_to_r18" [crypto/sha256_generic.ko] undefined!
| ERROR: "__ld_r13_to_r17_ret" [crypto/sha256_generic.ko] undefined!
| ERROR: "__st_r13_to_r17" [crypto/sha256_generic.ko] undefined!
| ERROR: "__ld_r13_to_r16_ret" [crypto/sha256_generic.ko] undefined!
| ERROR: "__st_r13_to_r16" [crypto/sha256_generic.ko] undefined!
|....
|....
Workaround that by inhibiting millicode thunks for loadable modules
Fixes STAR 9000641864:
("Linux built with optimizations for size emits errors for modules")
Reported-by: Anton Kolesov <akolesov@synosys.com>
Cc: Michal Marek <mmarek@suse.cz>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
diff --git a/arch/arc/Makefile b/arch/arc/Makefile
index cf0cf34..aeb1902 100644
--- a/arch/arc/Makefile
+++ b/arch/arc/Makefile
@@ -81,7 +81,7 @@
LIBGCC := $(shell $(CC) $(cflags-y) --print-libgcc-file-name)
# Modules with short calls might break for calls into builtin-kernel
-KBUILD_CFLAGS_MODULE += -mlong-calls
+KBUILD_CFLAGS_MODULE += -mlong-calls -mno-millicode
# Finally dump eveything into kernel build system
KBUILD_CFLAGS += $(cflags-y)
