netbsd.h (ENABLE_EXECUTE_STACK): Remove.

2011-05-29  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
	    Joseph Myers  <joseph@codesourcery.com>

	gcc:
	* config/alpha/netbsd.h (ENABLE_EXECUTE_STACK): Remove.
	(HAVE_ENABLE_EXECUTE_STACK): Define.
	* config/alpha/osf5.h (ENABLE_EXECUTE_STACK): Remove.
	(HAVE_ENABLE_EXECUTE_STACK): Define.
	* config/darwin.h (ENABLE_EXECUTE_STACK): Remove.
	(HAVE_ENABLE_EXECUTE_STACK): Define.
	* config/i386/mingw32.h (MINGW_ENABLE_EXECUTE_STACK): Remove.
	(ENABLE_EXECUTE_STACK): Remove.
	(HAVE_ENABLE_EXECUTE_STACK): Define.
	[IN_LIBGCC2]: Don't include <windows.h>.
	* config/i386/netbsd-elf.h (ENABLE_EXECUTE_STACK): Remove.
	(HAVE_ENABLE_EXECUTE_STACK): Define.
	* config/i386/netbsd64.h (ENABLE_EXECUTE_STACK): Remove.
	(HAVE_ENABLE_EXECUTE_STACK): Define.
	* config/netbsd.h (NETBSD_ENABLE_EXECUTE_STACK): Remove.
	* config/openbsd.h (ENABLE_EXECUTE_STACK): Remove.
	(HAVE_ENABLE_EXECUTE_STACK): Define.
	* config/sol2.h (ENABLE_EXECUTE_STACK): Remove.
	(HAVE_ENABLE_EXECUTE_STACK): Define.
	* config/sparc/freebsd.h (ENABLE_EXECUTE_STACK): Remove.
	(HAVE_ENABLE_EXECUTE_STACK): Define.
	* config/sparc/netbsd-elf.h (ENABLE_EXECUTE_STACK): Remove.
	(HAVE_ENABLE_EXECUTE_STACK): Define.
	* config/alpha/alpha.c (alpha_trampoline_init): Test
	HAVE_ENABLE_EXECUTE_STACK.
	* config/i386/i386.c (ix86_trampoline_init): Likewise.
	* config/sparc/sparc.c (sparc32_initialize_trampoline): Likewise.
	(sparc64_initialize_trampoline): Likewise.
	* libgcc2.c [L_enable_execute_stack]: Remove.
	* system.h (ENABLE_EXECUTE_STACK): Poison.
	* doc/tm.texi.in (Trampolines, ENABLE_EXECUTE_STACK): Remove.
	* doc/tm.texi: Regenerate.
	* Makefile.in (LIBGCC2_CFLAGS): Add -fbuilding-libgcc.

	gcc/c-family:
	* c.opt (fbuilding-libgcc): New option.
	* c-cppbuiltin.c (c_cpp_builtins): Define
	__LIBGCC_TRAMPOLINE_SIZE__ if flag_building_libgcc.

	libgcc:
	* enable-execute-stack-empty.c: New file.
	* enable-execute-stack-mprotect.c: New file.
	* config/i386/enable-execute-stack-mingw32.c: New file.
	* config.host (enable_execute_stack): New variable.
	Select appropriate variants.
	* configure.ac: Link enable-execute-stack.c to
	$enable_execute_stack.
	* configure: Regenerate.
	* Makefile.in (LIB2ADD): Add enable-execute-stack.c.
	(lib2funcs): Remove _enable_execute_stack.

Co-Authored-By: Joseph Myers <joseph@codesourcery.com>

From-SVN: r174843

8 files changed, 200 insertions, 1 deletions

diff --git a/libgcc/ChangeLog b/libgcc/ChangeLog
index c84bb05..75e7ef0 100644
--- a/libgcc/ChangeLog
+++ b/libgcc/ChangeLog
@@ -1,3 +1,16 @@
+2011-06-09  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
+
+	* enable-execute-stack-empty.c: New file.
+	* enable-execute-stack-mprotect.c: New file.
+	* config/i386/enable-execute-stack-mingw32.c: New file.
+	* config.host (enable_execute_stack): New variable.
+	Select appropriate variants.
+	* configure.ac: Link enable-execute-stack.c to
+	$enable_execute_stack.
+	* configure: Regenerate.
+	* Makefile.in (LIB2ADD): Add enable-execute-stack.c.
+	(lib2funcs): Remove _enable_execute_stack.
+
 2011-06-09  David S. Miller  <davem@davemloft.net>
 	    Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
 
diff --git a/libgcc/Makefile.in b/libgcc/Makefile.in
index 4a075ff..383a661 100644
--- a/libgcc/Makefile.in
+++ b/libgcc/Makefile.in
@@ -313,9 +313,11 @@ ifneq ($(GCC_EXTRA_PARTS),)
 endif
 endif
 
+LIB2ADD += enable-execute-stack.c
+
 # Library members defined in libgcc2.c.
 lib2funcs = _muldi3 _negdi2 _lshrdi3 _ashldi3 _ashrdi3 _cmpdi2 _ucmpdi2	   \
-	    _clear_cache _enable_execute_stack _trampoline __main _absvsi2 \
+	    _clear_cache _trampoline __main _absvsi2 \
 	    _absvdi2 _addvsi3 _addvdi3 _subvsi3 _subvdi3 _mulvsi3 _mulvdi3 \
 	    _negvsi2 _negvdi2 _ctors _ffssi2 _ffsdi2 _clz _clzsi2 _clzdi2  \
 	    _ctzsi2 _ctzdi2 _popcount_tab _popcountsi2 _popcountdi2	   \
diff --git a/libgcc/config.host b/libgcc/config.host
index 38b0eb3..c2b5dbc 100644
--- a/libgcc/config.host
+++ b/libgcc/config.host
@@ -44,6 +44,8 @@
 #			The default is ".hidden".
 #  cpu_type		The name of the cpu, if different from the first
 #			chunk of the canonical host name.
+#  enable_execute_stack The name of a source file implementing
+#			__enable_execute_stack.
 #  extra_parts		List of extra object files that should be compiled
 #			for this target machine.  This may be overridden
 #			by setting EXTRA_PARTS in a tmake_file fragment.
@@ -57,6 +59,7 @@
 #			"$cpu_type/t-$cpu_type".
 
 asm_hidden_op=.hidden
+enable_execute_stack=
 extra_parts=
 tmake_file=
 md_unwind_header=no-unwind.h
@@ -203,6 +206,19 @@ case ${host} in
 esac
 
 case ${host} in
+*-*-darwin* | *-*-freebsd* | *-*-netbsd* | *-*-openbsd* | *-*-solaris2* | \
+  alpha*-dec-osf5.1*)
+  enable_execute_stack=enable-execute-stack-mprotect.c
+  ;;
+i[34567]86-*-mingw* | x86_64-*-mingw*)
+  enable_execute_stack=config/i386/enable-execute-stack-mingw32.c
+  ;;
+*)
+  enable_execute_stack=enable-execute-stack-empty.c;
+  ;;
+esac
+
+case ${host} in
 # Support site-specific machine types.
 *local*)
 	rest=`echo ${host} | sed -e "s/$cpu_type-//"`
diff --git a/libgcc/config/i386/enable-execute-stack-mingw32.c b/libgcc/config/i386/enable-execute-stack-mingw32.c
new file mode 100644
index 0000000..8f3d272
--- /dev/null
+++ b/libgcc/config/i386/enable-execute-stack-mingw32.c
@@ -0,0 +1,38 @@
+/* Implement __enable_execute_stack for Windows32.
+   Copyright (C) 2011 Free Software Foundation, Inc.
+
+   This file is part of GCC.
+
+   GCC is free software; you can redistribute it and/or modify it under
+   the terms of the GNU General Public License as published by the Free
+   Software Foundation; either version 3, or (at your option) any later
+   version.
+
+   GCC 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 General Public License
+   for more details.
+
+   Under Section 7 of GPL version 3, you are granted additional
+   permissions described in the GCC Runtime Library Exception, version
+   3.1, as published by the Free Software Foundation.
+
+   You should have received a copy of the GNU General Public License and
+   a copy of the GCC Runtime Library Exception along with this program;
+   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <windows.h>
+
+extern void __enable_execute_stack (void *);
+
+void
+__enable_execute_stack (void *addr)
+{
+  MEMORY_BASIC_INFORMATION b;
+
+  if (!VirtualQuery (addr, &b, sizeof(b)))
+    abort ();
+  VirtualProtect (b.BaseAddress, b.RegionSize, PAGE_EXECUTE_READWRITE,
+		  &b.Protect);
+}
diff --git a/libgcc/configure b/libgcc/configure
index 1a3a0bd..1351022 100644
--- a/libgcc/configure
+++ b/libgcc/configure
@@ -3962,6 +3962,8 @@ tmake_file="${tmake_file_}"
 
 
 
+ac_config_links="$ac_config_links enable-execute-stack.c:$enable_execute_stack"
+
 ac_config_links="$ac_config_links md-unwind-support.h:config/$md_unwind_header"
 
 
@@ -4689,6 +4691,7 @@ cat >>$CONFIG_STATUS <<\_ACEOF || ac_write_fail=1
 for ac_config_target in $ac_config_targets
 do
   case $ac_config_target in
+    "enable-execute-stack.c") CONFIG_LINKS="$CONFIG_LINKS enable-execute-stack.c:$enable_execute_stack" ;;
     "md-unwind-support.h") CONFIG_LINKS="$CONFIG_LINKS md-unwind-support.h:config/$md_unwind_header" ;;
     "Makefile") CONFIG_FILES="$CONFIG_FILES Makefile" ;;
     "default") CONFIG_COMMANDS="$CONFIG_COMMANDS default" ;;
diff --git a/libgcc/configure.ac b/libgcc/configure.ac
index f2bcabf..4f56c3b 100644
--- a/libgcc/configure.ac
+++ b/libgcc/configure.ac
@@ -278,6 +278,7 @@ AC_SUBST(tmake_file)
 AC_SUBST(cpu_type)
 AC_SUBST(extra_parts)
 AC_SUBST(asm_hidden_op)
+AC_CONFIG_LINKS([enable-execute-stack.c:$enable_execute_stack])
 AC_CONFIG_LINKS([md-unwind-support.h:config/$md_unwind_header])
 
 # We need multilib support.
diff --git a/libgcc/enable-execute-stack-empty.c b/libgcc/enable-execute-stack-empty.c
new file mode 100644
index 0000000..81786de
--- /dev/null
+++ b/libgcc/enable-execute-stack-empty.c
@@ -0,0 +1,7 @@
+/* Dummy implementation of __enable_execute_stack.  */
+
+/* Attempt to turn on execute permission for the stack.  */
+void
+__enable_execute_stack (void *addr __attribute__((__unused__)))
+{
+}
diff --git a/libgcc/enable-execute-stack-mprotect.c b/libgcc/enable-execute-stack-mprotect.c
new file mode 100644
index 0000000..1ad77bd
--- /dev/null
+++ b/libgcc/enable-execute-stack-mprotect.c
@@ -0,0 +1,119 @@
+/* Implement __enable_execute_stack using mprotect(2).
+   Copyright (C) 2011 Free Software Foundation, Inc.
+
+   This file is part of GCC.
+
+   GCC is free software; you can redistribute it and/or modify it under
+   the terms of the GNU General Public License as published by the Free
+   Software Foundation; either version 3, or (at your option) any later
+   version.
+
+   GCC 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 General Public License
+   for more details.
+
+   Under Section 7 of GPL version 3, you are granted additional
+   permissions described in the GCC Runtime Library Exception, version
+   3.1, as published by the Free Software Foundation.
+
+   You should have received a copy of the GNU General Public License and
+   a copy of the GCC Runtime Library Exception along with this program;
+   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <sys/mman.h>
+#include <unistd.h>
+#include <stdlib.h>
+
+#define STACK_PROT_RWX (PROT_READ | PROT_WRITE | PROT_EXEC)
+
+static int need_enable_exec_stack;
+
+static void check_enabling (void) __attribute__ ((unused));
+extern void __enable_execute_stack (void *);
+
+#if defined __FreeBSD__
+#include <sys/sysctl.h>
+
+static void __attribute__ ((constructor))
+check_enabling (void)
+{
+  int prot = 0;
+  size_t len = sizeof (prot);
+
+  sysctlbyname ("kern.stackprot", &prot, &len, NULL, 0);
+  if (prot != STACK_PROT_RWX)
+    need_enable_exec_stack = 1;
+}
+#elif defined __sun__ && defined __svr4__
+static void __attribute__ ((constructor))
+check_enabling (void)
+{
+  int prot = (int) sysconf (_SC_STACK_PROT);
+
+  if (prot != STACK_PROT_RWX)
+    need_enable_exec_stack = 1;
+}
+#else
+/* There is no way to query the execute permission of the stack, so
+   we always issue the mprotect() call.  */
+
+static int need_enable_exec_stack = 1;
+#endif
+
+#if defined __NetBSD__
+/* Note that we go out of our way to use namespace-non-invasive calls
+   here.  Unfortunately, there is no libc-internal name for mprotect().  */
+
+#include <sys/sysctl.h>
+
+extern int __sysctl (int *, unsigned int, void *, size_t *, void *, size_t);
+
+static int
+getpagesize (void)
+{
+  static int size;
+
+  if (size == 0)
+    {
+      int mib[2];
+      size_t len;
+
+      mib[0] = CTL_HW;
+      mib[1] = HW_PAGESIZE;
+      len = sizeof (size);
+      (void) __sysctl (mib, 2, &size, &len, NULL, 0);
+    }
+  return size;
+}
+#endif /* __NetBSD__ */
+
+/* Attempt to turn on access permissions for the stack.  Unfortunately it
+   is not possible to make this namespace-clean.*/
+
+void
+__enable_execute_stack (void *addr)
+{
+  if (!need_enable_exec_stack)
+    return;
+  else
+    {
+      static long size, mask;
+
+      if (size == 0) {
+	size = getpagesize ();
+	mask = ~(size - 1);
+      }
+
+      char *page = (char *) (((long) addr) & mask);
+      char *end  = (char *)
+	((((long) (addr + __LIBGCC_TRAMPOLINE_SIZE__)) & mask) + size);
+
+      if (mprotect (page, end - page, STACK_PROT_RWX) < 0)
+	/* Note that no errors should be emitted by this code; it is
+	   considered dangerous for library calls to send messages to
+	   stdout/stderr.  */
+	abort ();
+    }
+}