From 95f5a9a866695da4e038aa4e6ccbbfd5d9cf63b7 Mon Sep 17 00:00:00 2001 From: Joseph Myers Date: Tue, 3 Jul 2012 19:14:59 +0000 Subject: Avoid use of libgcc_s and libgcc_eh when building glibc. --- Makeconfig | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 59 insertions(+), 9 deletions(-) (limited to 'Makeconfig') diff --git a/Makeconfig b/Makeconfig index 417fa508a6..859b588e00 100644 --- a/Makeconfig +++ b/Makeconfig @@ -415,9 +415,9 @@ LDFLAGS.so += $(hashstyle-LDFLAGS) LDFLAGS-rtld += $(hashstyle-LDFLAGS) endif -# Command for linking programs with the C library. +# Commands for linking programs with the C library. ifndef +link -+link = $(CC) -nostdlib -nostartfiles -o $@ \ ++link-before-libc = $(CC) -nostdlib -nostartfiles -o $@ \ $(sysdep-LDFLAGS) $(config-LDFLAGS) $(LDFLAGS) $(LDFLAGS-$(@F)) \ $(combreloc-LDFLAGS) $(relro-LDFLAGS) $(hashstyle-LDFLAGS) \ $(addprefix $(csu-objpfx),$(start-installed-name)) \ @@ -426,7 +426,10 @@ ifndef +link $(start-installed-name))\ $(+preinit) $(link-extra-libs) \ $(common-objpfx)libc% $(+postinit),$^) \ - $(link-extra-libs) $(link-libc) $(+postctor) $(+postinit) + $(link-extra-libs) ++link-after-libc = $(+postctor) $(+postinit) ++link = $(+link-before-libc) $(link-libc) $(+link-after-libc) ++link-tests = $(+link-before-libc) $(link-libc-tests) $(+link-after-libc) endif # Command for linking PIE programs with the C library. ifndef +link-pie @@ -443,7 +446,7 @@ ifndef +link-pie endif # Command for statically linking programs with the C library. ifndef +link-static -+link-static = $(CC) -nostdlib -nostartfiles -static -o $@ \ ++link-static-before-libc = $(CC) -nostdlib -nostartfiles -static -o $@ \ $(sysdep-LDFLAGS) $(LDFLAGS) $(LDFLAGS-$(@F)) \ $(addprefix $(csu-objpfx),$(static-start-installed-name)) \ $(+preinit) $(+prector) \ @@ -451,7 +454,12 @@ ifndef +link-static $(start-installed-name))\ $(+preinit) $(link-extra-libs-static) \ $(common-objpfx)libc% $(+postinit),$^) \ - $(link-extra-libs-static) $(link-libc-static) $(+postctor) $(+postinit) + $(link-extra-libs-static) $(link-libc-static) ++link-static-after-libc = $(+postctor) $(+postinit) ++link-static = $(+link-static-before-libc) $(link-libc-static) \ + $(+link-static-after-libc) ++link-static-tests = $(+link-static-before-libc) $(link-libc-static-tests) \ + $(+link-static-after-libc) endif # Command for statically linking bounded-pointer programs with the C library. ifndef +link-bounded @@ -475,10 +483,12 @@ ifeq (yes,$(build-shared)) # We need the versioned name of libc.so in the deps of $(others) et al # so that the symlink to libc.so is created before anything tries to # run the linked programs. -link-libc = -Wl,-rpath-link=$(rpath-link) \ +link-libc-before-gnulib = -Wl,-rpath-link=$(rpath-link) \ $(common-objpfx)libc.so$(libc.so-version) \ $(common-objpfx)$(patsubst %,$(libtype.oS),c) \ - $(as-needed) $(common-objpfx)elf/ld.so $(no-as-needed) $(gnulib) + $(as-needed) $(common-objpfx)elf/ld.so $(no-as-needed) +link-libc = $(link-libc-before-gnulib) $(gnulib) +link-libc-tests = $(link-libc-before-gnulib) $(gnulib-tests) # This is how to find at build-time things that will be installed there. rpath-dirs = math elf dlfcn nss nis rt resolv crypt rpath-link = \ @@ -488,6 +498,7 @@ else nssobjdir := $(patsubst ../$(subdir),.,$(common-objpfx)nss) resolvobjdir := $(patsubst ../$(subdir),.,$(common-objpfx)resolv) link-libc = $(common-objpfx)libc.a $(otherlibs) $(gnulib) $(common-objpfx)libc.a $(gnulib) +link-libc-tests = $(common-objpfx)libc.a $(otherlibs) $(gnulib-tests) $(common-objpfx)libc.a $(gnulib-tests) endif endif @@ -513,8 +524,43 @@ endif # The static libraries. link-libc-static = -Wl,--start-group $(common-objpfx)libc.a $(static-gnulib) -Wl,--end-group +link-libc-static-tests = -Wl,--start-group $(common-objpfx)libc.a $(static-gnulib-tests) -Wl,--end-group link-libc-bounded = $(common-objpfx)libc_b.a $(gnulib) $(common-objpfx)libc_b.a +# How to link against libgcc. Some libgcc functions, such as those +# for "long long" arithmetic or software floating point, can always be +# built without use of C library headers and do not have any global +# state so can safely be linked statically into any executable or +# shared library requiring them; these functions are in libgcc.a. +# Other functions, relating to exception handling, may require C +# library headers to build and it may not be safe to have more than +# one copy of them in a process; these functions are only in +# libgcc_s.so and libgcc_eh.a. +# +# To avoid circular dependencies when bootstrapping, it is desirable +# to avoid use of libgcc_s and libgcc_eh in building glibc. Where any +# glibc functionality (in particular, thread cancellation) requires +# exception handling, this is implemented through dlopen of libgcc_s +# to avoid unnecessary dependencies on libgcc_s by programs not using +# that functionality; executables built with glibc do not use +# exception handling other than through thread cancellation. +# +# Undefined references to functions from libgcc_eh or libgcc_s may +# arise for code built with -fexceptions. In the case of statically +# linked programs installed by glibc, unwinding will never actually +# occur at runtime and the use of elf/static-stubs.c to resolve these +# references is safe. In the case of statically linked test programs +# and test programs built with -fexceptions, unwinding may occur in +# some cases and it is preferable to link with libgcc_eh or libgcc_s +# so that the testing is as similar as possible to how programs will +# be built with the installed glibc. +# +# Some architectures have architecture-specific systems for exception +# handling that may involve undefined references to +# architecture-specific functions. On those architectures, +# gnulib-arch and static-gnulib-arch may be defined in sysdeps +# makefiles to use additional libraries for linking executables and +# shared libraries built by glibc. ifndef gnulib ifneq ($(have-cc-with-libunwind),yes) libunwind = @@ -522,8 +568,12 @@ else libunwind = -lunwind endif libgcc_eh := -Wl,--as-needed -lgcc_s $(libunwind) -Wl,--no-as-needed -gnulib := -lgcc $(libgcc_eh) -static-gnulib := -lgcc -lgcc_eh $(libunwind) +gnulib-arch = +gnulib = -lgcc $(gnulib-arch) +gnulib-tests := -lgcc $(libgcc_eh) +static-gnulib-arch = +static-gnulib = -lgcc $(static-gnulib-arch) +static-gnulib-tests := -lgcc -lgcc_eh $(libunwind) libc.so-gnulib := -lgcc endif +preinit = $(addprefix $(csu-objpfx),crti.o) -- cgit v1.2.3