Upstream-Status: Backport
Signed-off-by: Khem Raj <raj.khem@gmail.com>

From 95f5a9a866695da4e038aa4e6ccbbfd5d9cf63b7 Mon Sep 17 00:00:00 2001
From: Joseph Myers <joseph@codesourcery.com>
Date: Tue, 3 Jul 2012 19:14:59 +0000
Subject: [PATCH] Avoid use of libgcc_s and libgcc_eh when building glibc.

---
 ChangeLog                  |   47 ++++++++++++++++++++++++++++++
 Makeconfig                 |   68 ++++++++++++++++++++++++++++++++++++++------
 Rules                      |   45 ++++++++++++++++++++++-------
 elf/Makefile               |    6 +++-
 elf/static-stubs.c         |   46 ++++++++++++++++++++++++++++++
 ports/ChangeLog.arm        |    7 +++++
 ports/sysdeps/arm/Makefile |    8 ++++++
 7 files changed, 206 insertions(+), 21 deletions(-)
 create mode 100644 elf/static-stubs.c

Index: a/libc/Makeconfig
===================================================================
--- a/libc/Makeconfig	2012-07-04 18:26:22.000000000 -0700
+++ b/libc/Makeconfig	2012-08-14 20:16:10.197093639 -0700
@@ -415,9 +415,9 @@
 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 @@
 						     $(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 @@
 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 @@
 						     $(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 @@
 # 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 @@
 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 @@
 
 # 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 @@
   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)
Index: a/libc/Rules
===================================================================
--- a/libc/Rules	2012-07-04 18:25:47.000000000 -0700
+++ b/libc/Rules	2012-08-14 20:16:10.197093639 -0700
@@ -1,5 +1,4 @@
-# Copyright (C) 1991-2000,2002,2003,2004,2005,2006,2011
-#	Free Software Foundation, Inc.
+# Copyright (C) 1991-2012 Free Software Foundation, Inc.
 # This file is part of the GNU C Library.
 
 # The GNU C Library is free software; you can redistribute it and/or
@@ -103,29 +102,46 @@
 # eglibc: endif
 
 ifeq ($(build-programs),yes)
-binaries-all = $(others) $(sysdep-others) $(tests) $(xtests) $(test-srcs)
-binaries-static = $(others-static) $(tests-static) $(xtests-static)
+binaries-all-notests = $(others) $(sysdep-others)
+binaries-all-tests = $(tests) $(xtests) $(test-srcs)
+binaries-all = $(binaries-all-notests) $(binaries-all-tests)
+binaries-static-notests = $(others-static)
+binaries-static-tests = $(tests-static) $(xtests-static)
+binaries-static = $(binaries-static-notests) $(binaries-static-tests)
 ifeq (yesyes,$(have-fpie)$(build-shared))
 binaries-pie = $(others-pie) $(tests-pie) $(xtests-pie)
 else
 binaries-pie =
 endif
 else
-binaries-all = $(tests) $(xtests) $(test-srcs)
+binaries-all-notests =
+binaries-all-tests = $(tests) $(xtests) $(test-srcs)
+binaries-all = $(binaries-all-tests)
+binaries-static-notests =
+binaries-static-tests =
 binaries-static =
 binaries-pie =
 endif
 
-binaries-shared = $(filter-out $(binaries-pie) $(binaries-static), \
-			       $(binaries-all))
+binaries-shared-tests = $(filter-out $(binaries-pie) $(binaries-static), \
+				     $(binaries-all-tests))
+binaries-shared-notests = $(filter-out $(binaries-pie) $(binaries-static), \
+				       $(binaries-all-notests))
 
-ifneq "$(strip $(binaries-shared))" ""
-$(addprefix $(objpfx),$(binaries-shared)): %: %.o \
+ifneq "$(strip $(binaries-shared-notests))" ""
+$(addprefix $(objpfx),$(binaries-shared-notests)): %: %.o \
   $(sort $(filter $(common-objpfx)lib%,$(link-libc))) \
   $(addprefix $(csu-objpfx),start.o) $(+preinit) $(+postinit)
 	$(+link)
 endif
 
+ifneq "$(strip $(binaries-shared-tests))" ""
+$(addprefix $(objpfx),$(binaries-shared-tests)): %: %.o \
+  $(sort $(filter $(common-objpfx)lib%,$(link-libc))) \
+  $(addprefix $(csu-objpfx),start.o) $(+preinit) $(+postinit)
+	$(+link-tests)
+endif
+
 ifneq "$(strip $(binaries-pie))" ""
 $(addprefix $(objpfx),$(binaries-pie)): %: %.o \
   $(sort $(filter $(common-objpfx)lib%,$(link-libc))) \
@@ -133,13 +149,20 @@
 	$(+link-pie)
 endif
 
-ifneq "$(strip $(binaries-static))" ""
-$(addprefix $(objpfx),$(binaries-static)): %: %.o \
+ifneq "$(strip $(binaries-static-notests))" ""
+$(addprefix $(objpfx),$(binaries-static-notests)): %: %.o \
   $(sort $(filter $(common-objpfx)lib%,$(link-libc-static))) \
   $(addprefix $(csu-objpfx),start.o) $(+preinit) $(+postinit)
 	$(+link-static)
 endif
 
+ifneq "$(strip $(binaries-static-tests))" ""
+$(addprefix $(objpfx),$(binaries-static-tests)): %: %.o \
+  $(sort $(filter $(common-objpfx)lib%,$(link-libc-static-tests))) \
+  $(addprefix $(csu-objpfx),start.o) $(+preinit) $(+postinit)
+	$(+link-static-tests)
+endif
+
 ifeq ($(build-bounded),yes)
 binaries-bounded = $(addsuffix -bp,$(tests) $(xtests) $(test-srcs))
 $(addprefix $(objpfx),$(binaries-bounded)): %-bp: %.ob \
Index: a/libc/elf/Makefile
===================================================================
--- a/libc/elf/Makefile	2012-07-04 18:26:34.000000000 -0700
+++ b/libc/elf/Makefile	2012-08-14 20:16:10.197093639 -0700
@@ -71,6 +71,8 @@
 install-bin	= sprof pldd
 others-static   = sln
 install-rootsbin = sln
+sln-modules	:= static-stubs
+extra-objs	+= $(sln-modules:=.o)
 
 ifeq (yes,$(use-ldconfig))
 ifeq (yes,$(build-shared))
@@ -78,7 +80,7 @@
 others		+= ldconfig
 install-rootsbin += ldconfig
 
-ldconfig-modules := cache readlib xmalloc xstrdup chroot_canon
+ldconfig-modules := cache readlib xmalloc xstrdup chroot_canon static-stubs
 extra-objs	+= $(ldconfig-modules:=.o)
 endif
 endif
@@ -417,6 +419,8 @@
 
 $(objpfx)sprof: $(libdl)
 
+$(objpfx)sln: $(sln-modules:%=$(objpfx)%.o)
+
 $(objpfx)ldconfig: $(ldconfig-modules:%=$(objpfx)%.o)
 
 $(objpfx)pldd: $(pldd-modules:%=$(objpfx)%.o)
Index: a/libc/elf/static-stubs.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ a/libc/elf/static-stubs.c	2012-08-14 20:16:10.197093639 -0700
@@ -0,0 +1,46 @@
+/* Stub implementations of functions to link into statically linked
+   programs without needing libgcc_eh.
+   Copyright (C) 2012 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* Avoid backtrace (and so _Unwind_Backtrace) dependencies from
+   sysdeps/unix/sysv/linux/libc_fatal.c.  */
+#include <sysdeps/posix/libc_fatal.c>
+
+#include <stdlib.h>
+#include <unwind.h>
+
+/* These programs do not use thread cancellation, so _Unwind_Resume
+   and the personality routine are never actually called.  */
+
+void
+_Unwind_Resume (struct _Unwind_Exception *exc __attribute__ ((unused)))
+{
+  abort ();
+}
+
+_Unwind_Reason_Code
+__gcc_personality_v0 (int version __attribute__ ((unused)),
+		      _Unwind_Action actions __attribute__ ((unused)),
+		      _Unwind_Exception_Class exception_class
+		      __attribute__ ((unused)),
+		      struct _Unwind_Exception *ue_header
+		      __attribute__ ((unused)),
+		      struct _Unwind_Context *context __attribute__ ((unused)))
+{
+  abort ();
+}
Index: a/ports/sysdeps/arm/Makefile
===================================================================
--- a/ports/sysdeps/arm/Makefile	2012-07-04 18:25:41.000000000 -0700
+++ b/ports/sysdeps/arm/Makefile	2012-08-14 20:16:10.201093638 -0700
@@ -1,8 +1,16 @@
+gnulib-arch = $(elfobjdir)/libgcc-stubs.a
+static-gnulib-arch = $(elfobjdir)/libgcc-stubs.a
+
 ifeq ($(subdir),elf)
 sysdep-dl-routines += tlsdesc dl-tlsdesc
 sysdep_routines += aeabi_unwind_cpp_pr1 find_exidx tlsdesc dl-tlsdesc
 sysdep-rtld-routines += aeabi_unwind_cpp_pr1 tlsdesc dl-tlsdesc
 shared-only-routines += aeabi_unwind_cpp_pr1
+
+$(objpfx)libgcc-stubs.a: $(objpfx)aeabi_unwind_cpp_pr1.os
+	$(build-extra-lib)
+
+lib-noranlib: $(objpfx)libgcc-stubs.a
 endif
 
 ifeq ($(subdir),csu)
