Eliminate .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 everys
time given shared library is being relocated and making affected text pages
non-shareable.

Reviewed by:        kib
Approved by:        re (kensmith)

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:
 #

gnu/lib/libgcc/Makefile

@@ -6,6 +6,12 @@ LIB=		gcc
 SHLIB_NAME=	libgcc_s.so.1
 SHLIBDIR?=	/lib
 
+#
+# libgcc is linked in last and thus cannot depend on ssp symbols coming
+# from earlier libraries. Disable stack protection for this library.
+#
+WITHOUT_SSP=	yes
+
 .include <bsd.own.mk>
 .include "${.CURDIR}/../../usr.bin/cc/Makefile.tgt"
 
@@ -18,7 +24,7 @@ CFLAGS+=	-DIN_GCC -DIN_LIBGCC2 -D__GCC_FLOAT_NOT_NEEDED \
 		-I${.CURDIR}/../../usr.bin/cc/cc_tools
 
 LDFLAGS+=	-nodefaultlibs
-LDADD+=		-lc
+LDADD+=		-lc -lssp_nonshared
 
 OBJS=		# added to below in various ways depending on TARGET_ARCH
 

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>

gnu/usr.bin/cc/cc_tools/freebsd-native.h

@@ -62,3 +62,11 @@
 
 /* FreeBSD is 4.4BSD derived */
 #define bsd4_4
+
+/*
+ * Link in libssp_nonshared to get local hidden symbol for
+ * __stack_chk_fail_local into each binary that needs it.
+ * Linux does this with static part of their libc.so linker script, we reuse
+ * libssp_nonshared.a for the same purpose.
+ */
+#define LINK_SSP_SPEC "%{fstack-protector|fstack-protector-all:-lssp_nonshared}"

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
-__stack_chk_fail_local(void)
-{
-	__stack_chk_fail();
-}
+__sym_compat(__stack_chk_fail_local, __stack_chk_fail, FBSD_1.0);

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"