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From: Al Viro <viro@ZenIV.linux.org.uk>
To: linux-arch@vger.kernel.org
Cc: linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v2 01/13] [kbuild] handle exports in lib-y objects reliably
Date: Wed,  3 Feb 2016 21:20:33 +0000	[thread overview]
Message-ID: <1454534445-16759-1-git-send-email-viro@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20160203211953.GT17997@ZenIV.linux.org.uk>

From: Al Viro <viro@zeniv.linux.org.uk>

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.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 arch/ia64/hp/sim/boot/Makefile |  2 +-
 arch/ia64/lib/Makefile         |  8 +++-----
 scripts/Makefile.build         | 20 ++++++++++++++++++++
 3 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/arch/ia64/hp/sim/boot/Makefile b/arch/ia64/hp/sim/boot/Makefile
index 2e805e0..df6e996 100644
--- a/arch/ia64/hp/sim/boot/Makefile
+++ b/arch/ia64/hp/sim/boot/Makefile
@@ -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)
diff --git a/arch/ia64/lib/Makefile b/arch/ia64/lib/Makefile
index 98771e2..1f3d387 100644
--- a/arch/ia64/lib/Makefile
+++ b/arch/ia64/lib/Makefile
@@ -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	=
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 2c47f9c..d041013 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -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)),)
@@ -363,6 +364,25 @@ $(lib-target): $(lib-y) FORCE
 	$(call if_changed,link_l_target)
 
 targets += $(lib-target)
+
+dummy-object = $(obj)/__lib_exports.o
+ksyms-lds = $(obj)/lib-ksyms.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
 
 #
-- 
2.1.4

  reply	other threads:[~2016-02-03 21:20 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-29 19:17 [RFC][PATCHSET] allowing exports in *.S Al Viro
2016-01-29 19:18 ` [PATCH 01/12] [kbuild] handle exports in lib-y objects reliably Al Viro
2016-01-29 19:18 ` [PATCH 02/12] EXPORT_SYMBOL() for asm Al Viro
2016-01-29 21:06   ` Arnd Bergmann
2016-01-29 19:18 ` [PATCH 03/12] x86: move exports to actual definitions Al Viro
2016-02-01  8:12   ` Thomas Gleixner
2016-01-29 19:18 ` [PATCH 04/12] alpha: " Al Viro
2016-01-29 19:18 ` [PATCH 05/12] m68k: move exports to definitions Al Viro
2016-02-01 10:52   ` Geert Uytterhoeven
2016-02-01 12:18     ` Al Viro
2016-02-01 13:30       ` Geert Uytterhoeven
2016-02-01 14:53         ` Al Viro
2016-02-01 15:32           ` Geert Uytterhoeven
2016-01-29 19:18 ` [PATCH 06/12] s390: " Al Viro
2016-02-02 11:29   ` Heiko Carstens
2016-01-29 19:18 ` [PATCH 07/12] arm: " Al Viro
2016-01-29 19:18 ` [PATCH 08/12] ppc: " Al Viro
2016-01-29 19:18 ` [PATCH 09/12] sparc: " Al Viro
2016-01-30  7:08   ` David Miller
2016-01-29 19:18 ` [PATCH 10/12] ia64: " Al Viro
2016-01-29 19:18 ` [PATCH 11/12] [sparc] unify 32bit and 64bit string.h Al Viro
2016-01-30  7:08   ` David Miller
2016-01-29 19:18 ` [PATCH 12/12] sparc32: debride memcpy.S a bit Al Viro
2016-01-30  7:07   ` David Miller
2016-02-01 15:12 ` [PATCH 02/12] EXPORT_SYMBOL() for asm David Howells
2016-02-03 21:19 ` [RFC][PATCHSET v2] allowing exports in *.S Al Viro
2016-02-03 21:20   ` Al Viro [this message]
2016-02-04 22:33     ` [PATCH v2 01/13] [kbuild] handle exports in lib-y objects reliably Michal Marek
2016-02-05  0:18       ` Al Viro
2016-02-03 21:20   ` [PATCH v2 02/13] EXPORT_SYMBOL() for asm Al Viro
2016-02-04 18:06     ` Al Viro
2016-02-10 22:15     ` Nicolas Pitre
2016-02-03 21:20   ` [PATCH v2 03/13] x86: move exports to actual definitions Al Viro
2016-02-03 21:20   ` [PATCH v2 04/13] alpha: " Al Viro
2016-02-03 21:20   ` [PATCH v2 05/13] m68k: move exports to definitions Al Viro
2016-02-03 21:20   ` [PATCH v2 06/13] s390: " Al Viro
2016-02-03 21:20   ` [PATCH v2 07/13] arm: " Al Viro
2016-02-10 21:56     ` Nicolas Pitre
2016-02-03 21:20   ` [PATCH v2 08/13] ppc: " Al Viro
2016-02-03 21:20   ` [PATCH v2 09/13] ppc: get rid of unreachable abs() implementation Al Viro
2016-02-03 21:20   ` [PATCH v2 10/13] sparc: move exports to definitions Al Viro
2016-02-03 21:20   ` [PATCH v2 11/13] [sparc] unify 32bit and 64bit string.h Al Viro
2016-02-03 21:20   ` [PATCH v2 12/13] sparc32: debride memcpy.S a bit Al Viro
2016-02-03 21:20   ` [PATCH v2 13/13] ia64: move exports to definitions Al Viro
2016-08-02 14:01   ` [RFC][PATCHSET v2] allowing exports in *.S Michal Marek
2016-08-16  5:48     ` Michal Marek
2016-08-16  5:57       ` Michal Marek

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