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powerpc/64: Linker on-demand sfpr functions for modules

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For final link, the powerpc64 linker generates fpr save/restore
functions on-demand, placing them in the .sfpr section. Starting with
binutils 2.25, these can be provided for non-final links with
--save-restore-funcs. Use that where possible for module links.

This saves about 200 bytes per module (~60kB) on powernv defconfig
build.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Nicholas Piggin 2017-05-12 01:56:52 +10:00 committed by Michael Ellerman
parent cde9f2f420
commit efe0160cfd
2 changed files with 18 additions and 5 deletions
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10
arch/powerpc/Makefile
View file

@ -189,7 +189,17 @@ else
CHECKFLAGS += -D__LITTLE_ENDIAN__
endif
ifdef CONFIG_PPC32
KBUILD_LDFLAGS_MODULE += arch/powerpc/lib/crtsavres.o
else
ifeq ($(call ld-ifversion, -ge, 225000000, y),y)
# Have the linker provide sfpr if possible.
# There is a corresponding test in arch/powerpc/lib/Makefile
KBUILD_LDFLAGS_MODULE += --save-restore-funcs
else
KBUILD_LDFLAGS_MODULE += arch/powerpc/lib/crtsavres.o
endif
endif
ifeq ($(CONFIG_476FPE_ERR46),y)
KBUILD_LDFLAGS_MODULE += --ppc476-workaround \

13
arch/powerpc/lib/Makefile
View file

@ -11,12 +11,15 @@ CFLAGS_REMOVE_feature-fixups.o = $(CC_FLAGS_FTRACE)
obj-y += string.o alloc.o code-patching.o feature-fixups.o
# 64-bit linker creates .sfpr on demand for final link (vmlinux),
# so it is only needed for modules.
obj-$(CONFIG_PPC32) += crtsavres.o
extra-$(CONFIG_PPC64) += crtsavres.o
obj-$(CONFIG_PPC32) += div64.o copy_32.o crtsavres.o
obj-$(CONFIG_PPC32) += div64.o copy_32.o
# See corresponding test in arch/powerpc/Makefile
# 64-bit linker creates .sfpr on demand for final link (vmlinux),
# so it is only needed for modules, and only for older linkers which
# do not support --save-restore-funcs
ifeq ($(call ld-ifversion, -lt, 225000000, y),y)
extra-$(CONFIG_PPC64) += crtsavres.o
endif
obj64-y += copypage_64.o copyuser_64.o mem_64.o hweight_64.o \
copyuser_power7.o string_64.o copypage_power7.o memcpy_power7.o \