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[kbuild] handle exports in lib-y objects reliably

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Collect the symbols exported by anything that goes into lib.a and
add an empty object (lib-exports.o) with explicit undefs for each
of those to obj-y.

That allows to relax the rules regarding the use of exports in
lib-* objects - right now an object with export can be in lib-*
only if we are guaranteed that there always will be users in
built-in parts of the tree, otherwise it needs to be in obj-*.
As the result, we have an unholy mix of lib- and obj- in lib/Makefile
and (especially) in arch/*/lib/Makefile.  Moreover, a change in
generic part of the kernel can lead to mysteriously missing exports
on some configs.  With this change we don't have to worry about
that anymore.

One side effect is that built-in.o now pulls everything with exports
from the corresponding lib.a (if such exists).  That's exactly what
we want for linking vmlinux and fortunately it's almost the only thing
built-in.o is used in.  arch/ia64/hp/sim/boot/bootloader is the only
exception and it's easy to get rid of now - just turn everything in
arch/ia64/lib into lib-* and don't bother with arch/ia64/lib/built-in.o
anymore.

[AV: stylistic fix from Michal folded in]

Acked-by: Michal Marek <mmarek@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2016-01-15 14:01:22 -05:00
parent 29b4817d40
commit 7f2084fa55
3 changed files with 24 additions and 6 deletions
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2
arch/ia64/hp/sim/boot/Makefile
View File

@ -33,5 +33,5 @@ $(obj)/vmlinux.bin: vmlinux FORCE
LDFLAGS_bootloader = -static -T
$(obj)/bootloader: $(src)/bootloader.lds $(obj)/bootloader.o $(obj)/boot_head.o $(obj)/fw-emu.o \
lib/lib.a arch/ia64/lib/built-in.o arch/ia64/lib/lib.a FORCE
lib/lib.a arch/ia64/lib/lib.a FORCE
$(call if_changed,ld)

8
arch/ia64/lib/Makefile
View File

@ -2,17 +2,15 @@
# Makefile for ia64-specific library routines..
#
obj-y := io.o
lib-y := __divsi3.o __udivsi3.o __modsi3.o __umodsi3.o \
lib-y := io.o __divsi3.o __udivsi3.o __modsi3.o __umodsi3.o \
__divdi3.o __udivdi3.o __moddi3.o __umoddi3.o \
checksum.o clear_page.o csum_partial_copy.o \
clear_user.o strncpy_from_user.o strlen_user.o strnlen_user.o \
flush.o ip_fast_csum.o do_csum.o \
memset.o strlen.o xor.o
obj-$(CONFIG_ITANIUM) += copy_page.o copy_user.o memcpy.o
obj-$(CONFIG_MCKINLEY) += copy_page_mck.o memcpy_mck.o
lib-$(CONFIG_ITANIUM) += copy_page.o copy_user.o memcpy.o
lib-$(CONFIG_MCKINLEY) += copy_page_mck.o memcpy_mck.o
lib-$(CONFIG_PERFMON) += carta_random.o
AFLAGS___divdi3.o =

20
scripts/Makefile.build
View File

@ -81,6 +81,7 @@ endif
ifneq ($(strip $(lib-y) $(lib-m) $(lib-)),)
lib-target := $(obj)/lib.a
obj-y += $(obj)/lib-ksyms.o
endif
ifneq ($(strip $(obj-y) $(obj-m) $(obj-) $(subdir-m) $(lib-target)),)
@ -395,6 +396,25 @@ $(lib-target): $(lib-y) FORCE
$(call if_changed,link_l_target)
targets += $(lib-target)
dummy-object = $(obj)/.lib_exports.o
ksyms-lds = $(dot-target).lds
ifdef CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX
ref_prefix = EXTERN(_
else
ref_prefix = EXTERN(
endif
quiet_cmd_export_list = EXPORTS $@
cmd_export_list = $(OBJDUMP) -h $< | \
sed -ne '/___ksymtab/{s/.*+/$(ref_prefix)/;s/ .*/)/;p}' >$(ksyms-lds);\
rm -f $(dummy-object);\
$(AR) rcs$(KBUILD_ARFLAGS) $(dummy-object);\
$(LD) $(ld_flags) -r -o $@ -T $(ksyms-lds) $(dummy-object);\
rm $(dummy-object) $(ksyms-lds)
$(obj)/lib-ksyms.o: $(lib-target) FORCE
$(call if_changed,export_list)
endif
#