[PATCH] Unify linking of libasm, libelf, libdw, backends

[Ulf Hermann <ulf dot hermann at qt dot io>]

Link them all with -z,defs,-z,relro,--no-undefined, provide complete
dependencies for the link steps, and add libeu.a to each one. libeu.a
contains useful library functionality that each of them might use. The
linker will strip unneeded symbols, so linking it in won't hurt even if
none of the functions are used.

Signed-off-by: Ulf Hermann <ulf.hermann@qt.io>
---
 backends/Makefile.am |  7 ++++---
 libasm/Makefile.am   | 14 ++++++++------
 libdw/Makefile.am    | 15 +++++++++------
 libelf/Makefile.am   | 14 +++++++++-----
 4 files changed, 30 insertions(+), 20 deletions(-)

diff --git a/backends/Makefile.am b/backends/Makefile.am
index bfb6b84..79bd26c 100644
--- a/backends/Makefile.am
+++ b/backends/Makefile.am
@@ -45,6 +45,7 @@ noinst_DATA = $(libebl_pic:_pic.a=.so)
 
 libelf = ../libelf/libelf.so
 libdw = ../libdw/libdw.so
+libeu = ../lib/libeu.a
 
 i386_SRCS = i386_init.c i386_symbol.c i386_corenote.c i386_cfi.c \
 	    i386_retval.c i386_regs.c i386_auxv.c i386_syscall.c \
@@ -130,14 +131,14 @@ libebl_bpf_pic_a_SOURCES = $(bpf_SRCS)
 am_libebl_bpf_pic_a_OBJECTS = $(bpf_SRCS:.c=.os)
 
 
-libebl_%.so libebl_%.map: libebl_%_pic.a $(libelf) $(libdw)
+libebl_%.so libebl_%.map: libebl_%_pic.a $(libelf) $(libdw) $(libeu)
 	@rm -f $(@:.so=.map)
 	$(AM_V_at)echo 'ELFUTILS_$(PACKAGE_VERSION) { global: $*_init; local: *; };' \
 	  > $(@:.so=.map)
 	$(AM_V_CCLD)$(LINK) -shared -o $(@:.map=.so) \
 		-Wl,--whole-archive $< $(cpu_$*) -Wl,--no-whole-archive \
-		-Wl,--version-script,$(@:.so=.map) \
-		-Wl,-z,defs -Wl,--as-needed $(libelf) $(libdw)
+		-Wl,--version-script,$(@:.so=.map),--no-undefined \
+		-Wl,-z,defs,-z,relro -Wl,--as-needed $(libelf) $(libdw) $(libeu)
 	@$(textrel_check)
 
 libebl_i386.so: $(cpu_i386)
diff --git a/libasm/Makefile.am b/libasm/Makefile.am
index 8094b05..9effa6c 100644
--- a/libasm/Makefile.am
+++ b/libasm/Makefile.am
@@ -55,17 +55,19 @@ libasm_a_SOURCES = asm_begin.c asm_abort.c asm_end.c asm_error.c \
 libasm_pic_a_SOURCES =
 am_libasm_pic_a_OBJECTS = $(libasm_a_SOURCES:.c=.os)
 
-libasm_so_LDLIBS =
+libasm_so_DEPS = ../lib/libeu.a ../libebl/libebl.a ../libelf/libelf.so ../libdw/libdw.so
+libasm_so_LDLIBS = $(libasm_so_DEPS)
 if USE_LOCKS
 libasm_so_LDLIBS += -lpthread
 endif
 
+libasm_so_LIBS = libasm_pic.a
 libasm_so_SOURCES =
-libasm.so$(EXEEXT): libasm_pic.a libasm.map
-	$(AM_V_CCLD)$(LINK) -shared -o $@ -Wl,--whole-archive,$<,--no-whole-archive \
-		-Wl,--version-script,$(srcdir)/libasm.map,--no-undefined \
-		-Wl,--soname,$@.$(VERSION) \
-		../libebl/libebl.a ../libelf/libelf.so ../libdw/libdw.so \
+libasm.so$(EXEEXT): $(srcdir)/libasm.map $(libasm_so_LIBS) $(libasm_so_DEPS)
+	$(AM_V_CCLD)$(LINK) -shared -o $@ \
+		-Wl,--soname,$@.$(VERSION),-z,defs,-z,relro \
+		-Wl,--version-script,$<,--no-undefined \
+		-Wl,--whole-archive $(libasm_so_LIBS) -Wl,--no-whole-archive \
 		$(libasm_so_LDLIBS)
 	@$(textrel_check)
 	$(AM_V_at)ln -fs $@ $@.$(VERSION)
diff --git a/libdw/Makefile.am b/libdw/Makefile.am
index 082d96c..634ac2e 100644
--- a/libdw/Makefile.am
+++ b/libdw/Makefile.am
@@ -102,17 +102,20 @@ endif
 libdw_pic_a_SOURCES =
 am_libdw_pic_a_OBJECTS = $(libdw_a_SOURCES:.c=.os)
 
+libdw_so_LIBS = libdw_pic.a ../libdwelf/libdwelf_pic.a \
+	  ../libdwfl/libdwfl_pic.a ../libebl/libebl.a
+libdw_so_DEPS = ../lib/libeu.a ../libelf/libelf.so
+libdw_so_LDLIBS = $(libdw_so_DEPS) -ldl -lz $(argp_LDADD) $(zip_LIBS)
 libdw_so_SOURCES =
-libdw.so$(EXEEXT): $(srcdir)/libdw.map libdw_pic.a ../libdwelf/libdwelf_pic.a \
-	  ../libdwfl/libdwfl_pic.a ../libebl/libebl.a \
-	  ../libelf/libelf.so
+libdw.so$(EXEEXT): $(srcdir)/libdw.map $(libdw_so_LIBS) $(libdw_so_DEPS)
 # The rpath is necessary for libebl because its $ORIGIN use will
 # not fly in a setuid executable that links in libdw.
-	$(AM_V_CCLD)$(LINK) -shared -o $@ -Wl,--soname,$@.$(VERSION),-z,defs \
+	$(AM_V_CCLD)$(LINK) -shared -o $@ \
+		-Wl,--soname,$@.$(VERSION),-z,defs,-z,relro \
 		-Wl,--enable-new-dtags,-rpath,$(pkglibdir) \
 		-Wl,--version-script,$<,--no-undefined \
-		-Wl,--whole-archive $(filter-out $<,$^) -Wl,--no-whole-archive\
-		-ldl -lz $(argp_LDADD) $(zip_LIBS)
+		-Wl,--whole-archive $(libdw_so_LIBS) -Wl,--no-whole-archive \
+		$(libdw_so_LDLIBS)
 	@$(textrel_check)
 	$(AM_V_at)ln -fs $@ $@.$(VERSION)
 
diff --git a/libelf/Makefile.am b/libelf/Makefile.am
index 167a832..88c1edd 100644
--- a/libelf/Makefile.am
+++ b/libelf/Makefile.am
@@ -95,16 +95,20 @@ libelf_a_SOURCES = elf_version.c elf_hash.c elf_error.c elf_fill.c \
 libelf_pic_a_SOURCES =
 am_libelf_pic_a_OBJECTS = $(libelf_a_SOURCES:.c=.os)
 
-libelf_so_LDLIBS = -lz
+libelf_so_DEPS = ../lib/libeu.a
+libelf_so_LDLIBS = $(libelf_so_DEPS) -lz
 if USE_LOCKS
 libelf_so_LDLIBS += -lpthread
 endif
 
+libelf_so_LIBS = libelf_pic.a
 libelf_so_SOURCES =
-libelf.so$(EXEEXT): libelf_pic.a libelf.map
-	$(AM_V_CCLD)$(LINK) -shared -o $@ -Wl,--whole-archive,$<,--no-whole-archive \
-		-Wl,--version-script,$(srcdir)/libelf.map,--no-undefined \
-		-Wl,--soname,$@.$(VERSION),-z,defs,-z,relro $(libelf_so_LDLIBS)
+libelf.so$(EXEEXT): $(srcdir)/libelf.map $(libelf_so_LIBS) $(libelf_so_DEPS)
+	$(AM_V_CCLD)$(LINK) -shared -o $@ \
+		-Wl,--soname,$@.$(VERSION),-z,defs,-z,relro \
+		-Wl,--version-script,$<,--no-undefined \
+		-Wl,--whole-archive $(libelf_so_LIBS) -Wl,--no-whole-archive \
+		$(libelf_so_LDLIBS)
 	@$(textrel_check)
 	$(AM_V_at)ln -fs $@ $@.$(VERSION)
 
-- 
2.1.4