Commit 07fd7d4b authored Dec 21, 2015 by Vineet Gupta

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>

parent 4b32e89a

arch/arc/Makefile

+1 −1

Original line number	Diff line number	Diff line
		@@ -81,7 +81,7 @@ endif
		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)

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