[PATCH 03/14] Mark all machinery needed in early static-link init as -fno-stack-protector.

[Nix <nix@esperi.org.uk>]

From: Nick Alcock <nick.alcock@oracle.com>

The startup code in csu/, brk() and sbrk(), and the
__pthread_initialize_tcb_internal() function we just introduced are
needed very early in initialization of a statically-linked program,
before the stack guard is initialized. Mark all of these as
-fno-stack-protector.

We also finally introduce @libc_cv_ssp@, substituted by the configury
changes made much earlier, to detect the case when -fno-stack-protector
is supported by the compiler, and unconditionally pass it in when this
is the case, whether or not --enable-stack-protector is passed to
configure.  (This means that it'll even work when the compiler's been
hacked to pass -fstack-protector by default, unless the hackage is so
broken that it does so in a way that is impossible to override.)

(At one point we marked __libc_fatal() as non-stack-protected too,
but this was pointless: all it did was call other routines which *are*
stack-protected.  The earliest __libc_fatal() call is in the
DL_SYSDEP_OSCHECK hook on some platforms: this is fine, since it is
after TLS and stack-canary initialization.  I have tested invocation
of programs statically and dynamically linked against this glibc on
older kernels on x86, and they still "work", i.e. fail with the
appropriate message.)

v2: No longer mark memcpy() as -fno-stack-protector.
---
 config.make.in | 1 +
 csu/Makefile   | 7 +++++++
 misc/Makefile  | 6 ++++++
 nptl/Makefile  | 5 +++++
 4 files changed, 19 insertions(+)

diff --git a/config.make.in b/config.make.in
index 05ed6ec..847931f 100644
--- a/config.make.in
+++ b/config.make.in
@@ -55,6 +55,7 @@ with-fp = @with_fp@
 enable-timezone-tools = @enable_timezone_tools@
 unwind-find-fde = @libc_cv_gcc_unwind_find_fde@
 have-fpie = @libc_cv_fpie@
+have-ssp = @libc_cv_ssp@
 stack-protector = @stack_protector@
 have-selinux = @have_selinux@
 have-libaudit = @have_libaudit@
diff --git a/csu/Makefile b/csu/Makefile
index 31e8bb9..8d7cbb5 100644
--- a/csu/Makefile
+++ b/csu/Makefile
@@ -45,6 +45,13 @@ before-compile += $(objpfx)version-info.h
 tests := tst-empty tst-atomic tst-atomic-long
 tests-static := tst-empty
 
+ifeq ($(have-ssp),yes)
+CFLAGS-.o += -fno-stack-protector
+CFLAGS-.og += -fno-stack-protector
+CFLAGS-.op += -fno-stack-protector
+CFLAGS-.os += -fno-stack-protector
+endif
+
 ifeq (yes,$(build-shared))
 extra-objs += S$(start-installed-name) gmon-start.os
 ifneq ($(start-installed-name),$(static-start-installed-name))
diff --git a/misc/Makefile b/misc/Makefile
index d7bbc85..ba5c5d0 100644
--- a/misc/Makefile
+++ b/misc/Makefile
@@ -99,6 +99,12 @@ CFLAGS-getusershell.c = -fexceptions
 CFLAGS-err.c = -fexceptions
 CFLAGS-tst-tsearch.c = $(stack-align-test-flags)
 
+ifeq ($(have-ssp),yes)
+# Called during static library initialization.
+CFLAGS-sbrk.c = -fno-stack-protector
+CFLAGS-brk.c = -fno-stack-protector
+endif
+
 include ../Rules
 
 $(objpfx)libg.a: $(dep-dummy-lib); $(make-dummy-lib)
diff --git a/nptl/Makefile b/nptl/Makefile
index dc3ccab..a1d52a2 100644
--- a/nptl/Makefile
+++ b/nptl/Makefile
@@ -327,6 +327,11 @@ tests += tst-execstack
 endif
 endif
 
+ifeq ($(have-ssp),yes)
+# Parts of nptl-init.c are called before the stack guard is initialized.
+CFLAGS-nptl-init.c += -fno-stack-protector
+endif
+
 modules-names = tst-atfork2mod tst-tls3mod tst-tls4moda tst-tls4modb \
 		tst-tls5mod tst-tls5moda tst-tls5modb tst-tls5modc \
 		tst-tls5modd tst-tls5mode tst-tls5modf tst-stack4mod \
-- 
2.7.0.198.g6dd47b6