Second attempt at eliminating .text relocations in shared libraries

compiled with stack protector.

Use libssp_nonshared library to pull __stack_chk_fail_local symbol into
each library that needs it instead of pulling it from libc. GCC
generates local calls to this function which result in absolute
relocations put into position-independent code segment, making dynamic
loader do extra work every time given shared library is being relocated
and making affected text pages non-shareable.

Reviewed by:        kib
Approved by:        re (kib)

Makefile.inc1

@@ -1069,7 +1069,7 @@ libraries:
 #
 # static libgcc.a prerequisite for shared libc
 #
-_prereq_libs= gnu/lib/libgcc
+_prereq_libs= gnu/lib/libssp/libssp_nonshared gnu/lib/libgcc
 
 # These dependencies are not automatically generated:
 #

contrib/gcc/config/freebsd-spec.h

@@ -168,6 +168,7 @@ is built with the --enable-threads configure-time option.}		\
     %{pg:  %{pthread:-lpthread_p} -lc_p}}				\
   %{shared:								\
     %{pthread:-lpthread} -lc}						\
+  %{fstack-protector|fstack-protector-all:-lssp_nonshared}		\
   "
 #endif
 #endif

gnu/lib/libgcc/Makefile

@@ -7,6 +7,12 @@ SHLIB_NAME=	libgcc_s.so.1
 SHLIBDIR?=	/lib
 
 .include <bsd.own.mk>
+#
+# libgcc is linked in last and thus cannot depend on ssp symbols coming
+# from earlier libraries. Disable stack protection for this library.
+#
+MK_SSP=	no
+
 .include "${.CURDIR}/../../usr.bin/cc/Makefile.tgt"
 
 .PATH: ${GCCDIR}/config/${GCC_CPU} ${GCCDIR}/config ${GCCDIR}

gnu/lib/libssp/libssp_nonshared/Makefile

@@ -13,6 +13,6 @@ SRCS=	ssp-local.c
 
 CFLAGS+= -DHAVE_CONFIG_H
 CFLAGS+= -I${.CURDIR}/..  -I${GCCLIB}/libssp  -I${GCCLIB}/include
-CFLAGS+= -fPIC -DPIC
+CFLAGS+= -fPIC -DPIC -fvisibility=hidden
 
 .include <bsd.lib.mk>

lib/libc/Makefile

@@ -26,7 +26,7 @@ PRECIOUSLIB=
 #
 DPADD+=	${LIBGCC}
 LDFLAGS+= -nodefaultlibs
-LDADD+= -lgcc
+LDADD+= -lgcc -lssp_nonshared
 
 # Define (empty) variables so that make doesn't give substitution
 # errors if the included makefiles don't change these:

lib/libc/sys/Symbol.map

@@ -282,7 +282,6 @@ FBSD_1.0 {
 	socket;
 	socketpair;
 	__stack_chk_fail;
-	__stack_chk_fail_local;
 	__stack_chk_guard;
 	stat;
 	statfs;

lib/libc/sys/stack_protector.c

@@ -47,7 +47,6 @@ static void __guard_setup(void) __attribute__((__constructor__, __used__));
 static void __fail(const char *);
 void __stack_chk_fail(void);
 void __chk_fail(void);
-void __stack_chk_fail_local(void);
 
 /*LINTED used*/
 static void
@@ -109,8 +108,4 @@ __chk_fail(void)
 	__fail("buffer overflow detected; terminated");
 }
 
-void
+__sym_compat(__stack_chk_fail_local, __stack_chk_fail, FBSD_1.0);
-__stack_chk_fail_local(void)
-{
-	__stack_chk_fail();
-}

libexec/rtld-elf/Makefile

@@ -22,7 +22,7 @@ MLINKS=		rtld.1 ld-elf.so.1.1 \
 CFLAGS+=	-fpic -DPIC
 LDFLAGS+=	-shared -Wl,-Bsymbolic
 DPADD=		${LIBC_PIC}
-LDADD=		-lc_pic
+LDADD=		-lc_pic -lssp_nonshared
 
 .if ${MACHINE_ARCH} != "ia64"
 .if ${MK_SYMVER} == "yes"

share/mk/bsd.lib.mk

@@ -200,11 +200,11 @@ ${SHLIB_NAME}: ${SOBJS}
 	@ln -fs ${.TARGET} ${SHLIB_LINK}
 .endif
 .if !defined(NM)
-	@${CC} ${LDFLAGS} -shared -Wl,-x \
+	@${CC} ${LDFLAGS} ${SSP_CFLAGS} -shared -Wl,-x \
 	    -o ${.TARGET} -Wl,-soname,${SONAME} \
 	    `lorder ${SOBJS} | tsort -q` ${LDADD}
 .else
-	@${CC} ${LDFLAGS} -shared -Wl,-x \
+	@${CC} ${LDFLAGS} ${SSP_CFLAGS} -shared -Wl,-x \
 	    -o ${.TARGET} -Wl,-soname,${SONAME} \
 	    `NM='${NM}' lorder ${SOBJS} | tsort -q` ${LDADD}
 .endif