configure.ac (--enable-libssp): New.

2017-10-31  Sandra Loosemore  <sandra@codesourcery.com>

	gcc/
	* configure.ac (--enable-libssp): New.
	(gcc_cv_libc_provides_ssp): Check for explicit setting before
	trying to determine target-specific default.  Adjust indentation.
	* configure: Regenerated.
	* doc/install.texi (Configuration): Expand --disable-libssp
	documentation.

From-SVN: r254288

gcc/ChangeLog

+2017-10-31  Sandra Loosemore  <sandra@codesourcery.com>
+
+	* configure.ac (--enable-libssp): New.
+	(gcc_cv_libc_provides_ssp): Check for explicit setting before
+	trying to determine target-specific default.  Adjust indentation.
+	* configure: Regenerated.
+	* doc/install.texi (Configuration): Expand --disable-libssp
+	documentation.
+
 2017-10-31  Daniel Santos  <daniel.santos@pobox.com>
 
 	config/i386/i386.c (ix86_expand_epilogue): Correct stack

gcc/configure

@@ -942,6 +942,7 @@ enable_fix_cortex_a53_843419
 with_glibc_version
 enable_gnu_unique_object
 enable_linker_build_id
+enable_libssp
 enable_default_ssp
 with_long_double_128
 with_gc
@@ -1682,6 +1683,7 @@ Optional Features:
                           extension on glibc systems
   --enable-linker-build-id
                           compiler will always pass --build-id to linker
+  --enable-libssp         enable linking against libssp
   --enable-default-ssp    enable Stack Smashing Protection as default
   --enable-maintainer-mode
                           enable make rules and dependencies not useful (and
@@ -18440,7 +18442,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 18443 "configure"
+#line 18445 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -18546,7 +18548,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 18549 "configure"
+#line 18551 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -29040,6 +29042,18 @@ $as_echo "#define HAVE_SOLARIS_CRTS 1" >>confdefs.h
 
 fi
 
+# Check whether --enable-libssp was given.
+if test "${enable_libssp+set}" = set; then :
+  enableval=$enable_libssp; case "${enableval}" in
+  yes|no)
+    ;;
+  *)
+    as_fn_error "unknown libssp setting $enableval" "$LINENO" 5
+    ;;
+esac
+fi
+
+
 # Test for stack protector support in target C library.
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking __stack_chk_fail in target C library" >&5
 $as_echo_n "checking __stack_chk_fail in target C library... " >&6; }
@@ -29047,6 +29061,11 @@ if test "${gcc_cv_libc_provides_ssp+set}" = set; then :
   $as_echo_n "(cached) " >&6
 else
   gcc_cv_libc_provides_ssp=no
+  if test "x$enable_libssp" = "xno"; then
+    gcc_cv_libc_provides_ssp=yes
+  elif test "x$enable_libssp" = "xyes"; then
+    gcc_cv_libc_provides_ssp=no
+  else
     case "$target" in
        *-*-musl*)
 	 # All versions of musl provide stack protector
@@ -29094,8 +29113,9 @@ else
 fi
 
         ;;
-  *) gcc_cv_libc_provides_ssp=no ;;
+       *) gcc_cv_libc_provides_ssp=no ;;
     esac
+  fi
 fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_libc_provides_ssp" >&5
 $as_echo "$gcc_cv_libc_provides_ssp" >&6; }

gcc/configure.ac

@@ -5756,10 +5756,25 @@ if test x$gcc_cv_solaris_crts = xyes; then
   	    [Define if the system-provided CRTs are present on Solaris.])
 fi
 
+AC_ARG_ENABLE(libssp,
+[AS_HELP_STRING([--enable-libssp], [enable linking against libssp])],
+[case "${enableval}" in
+  yes|no)
+    ;;
+  *)
+    AC_MSG_ERROR([unknown libssp setting $enableval])
+    ;;
+esac], [])
+
 # Test for stack protector support in target C library.
 AC_CACHE_CHECK(__stack_chk_fail in target C library,
-      gcc_cv_libc_provides_ssp,
-      [gcc_cv_libc_provides_ssp=no
+  gcc_cv_libc_provides_ssp,
+  [gcc_cv_libc_provides_ssp=no
+  if test "x$enable_libssp" = "xno"; then
+    gcc_cv_libc_provides_ssp=yes
+  elif test "x$enable_libssp" = "xyes"; then
+    gcc_cv_libc_provides_ssp=no
+  else
     case "$target" in
        *-*-musl*)
 	 # All versions of musl provide stack protector
@@ -5796,8 +5811,9 @@ AC_CACHE_CHECK(__stack_chk_fail in target C library,
 	 AC_CHECK_FUNC(__stack_chk_fail,[gcc_cv_libc_provides_ssp=yes],
            [echo "no __stack_chk_fail on this target"])
         ;;
-  *) gcc_cv_libc_provides_ssp=no ;;
-    esac])
+       *) gcc_cv_libc_provides_ssp=no ;;
+    esac
+  fi])
 
 if test x$gcc_cv_libc_provides_ssp = xyes; then
   AC_DEFINE(TARGET_LIBC_PROVIDES_SSP, 1,

gcc/doc/install.texi

@@ -1640,7 +1640,8 @@ not be built.
 
 @item --disable-libssp
 Specify that the run-time libraries for stack smashing protection
-should not be built.
+should not be built or linked against.  On many targets library support
+is provided by the C library instead.
 
 @item --disable-libquadmath
 Specify that the GCC quad-precision math library should not be built.