common.opt: New option -fstack-protector-explicit.

2015-01-14  Marcos Diaz <marcos.diaz@tallertechnologies.com>

	* common.opt: New option -fstack-protector-explicit.
	* cfgexpand.c (SPCT_FLAG_EXPLICIT): New enum.
	(stack_protect_decl_phase): Handle stack_protect attribute for
	explicit stack protection requests.
	(expand_used_vars): Similarly.
	* doc/cpp.texi (__SSP_EXPLICIT__): Document predefined macro.
	* doc/extend.texi: Add documentation for "stack_protect" attribute.
	* doc/invoke.texi: Add documentation for -fstack-protector-explicit.

	* c-cppbuiltin.c (c_cpp_builtins): New cpp define __SSP_EXPLICIT__
	for the new option fstack-protector_explicit.
	* c-common.c (c_common_attribute_table): Add stack_protect attribute.
	(handle_stack_protect_attribute): New function.

	* gcc.dg/stackprotectexplicit1.c: New test.
	* g++.dg/stackprotectexplicit2.c: New test.

From-SVN: r219633

12 files changed, 147 insertions, 9 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 5e959c2..701c6c6 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,14 @@
+2015-01-14  Marcos Diaz <marcos.diaz@tallertechnologies.com>
+
+	* common.opt: New option -fstack-protector-explicit.
+	* cfgexpand.c (SPCT_FLAG_EXPLICIT): New enum.
+	(stack_protect_decl_phase): Handle stack_protect attribute for
+	explicit stack protection requests.
+	(expand_used_vars): Similarly.
+	* doc/cpp.texi (__SSP_EXPLICIT__): Document predefined macro.
+	* doc/extend.texi: Add documentation for "stack_protect" attribute.
+	* doc/invoke.texi: Add documentation for -fstack-protector-explicit.
+
 2015-01-14  Oleg Endo  <olegendo@gcc.gnu.org>
 
 	PR target/53988
diff --git a/gcc/c-family/ChangeLog b/gcc/c-family/ChangeLog
index 1efb75a..9764045 100644
--- a/gcc/c-family/ChangeLog
+++ b/gcc/c-family/ChangeLog
@@ -1,3 +1,10 @@
+2015-01-14  Marcos Diaz <marcos.diaz@tallertechnologies.com>
+
+	* c-cppbuiltin.c (c_cpp_builtins): New cpp define __SSP_EXPLICIT__
+	for the new option fstack-protector_explicit.
+	* c-common.c (c_common_attribute_table): Add stack_protect attribute.
+	(handle_stack_protect_attribute): New function.
+
 2015-01-13  Martin Uecker <uecker@eecs.berkeley.edu>
 
 	* c.opt: New option -Warray-bounds=.
diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index 29cab01..054f5a0 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -327,6 +327,7 @@ static tree handle_no_address_safety_analysis_attribute (tree *, tree, tree,
 							 int, bool *);
 static tree handle_no_sanitize_undefined_attribute (tree *, tree, tree, int,
 						    bool *);
+static tree handle_stack_protect_attribute (tree *, tree, tree, int, bool *);
 static tree handle_noinline_attribute (tree *, tree, tree, int, bool *);
 static tree handle_noclone_attribute (tree *, tree, tree, int, bool *);
 static tree handle_leaf_attribute (tree *, tree, tree, int, bool *);
@@ -657,6 +658,8 @@ const struct attribute_spec c_common_attribute_table[] =
 			      handle_noreturn_attribute, false },
   { "volatile",               0, 0, true,  false, false,
 			      handle_noreturn_attribute, false },
+  { "stack_protect",          0, 0, true,  false, false,
+			      handle_stack_protect_attribute, false },
   { "noinline",               0, 0, true,  false, false,
 			      handle_noinline_attribute, false },
   { "noclone",                0, 0, true,  false, false,
@@ -6769,6 +6772,25 @@ handle_no_sanitize_undefined_attribute (tree *node, tree name, tree, int,
   return NULL_TREE;
 }
 
+/* Handle a "stack_protect" attribute; arguments as in
+   struct attribute_spec.handler.  */
+static tree
+handle_stack_protect_attribute (tree *node, tree name, tree, int,
+				bool *no_add_attrs)
+{
+  if (TREE_CODE (*node) != FUNCTION_DECL)
+    {
+      warning (OPT_Wattributes, "%qE attribute ignored", name);
+      *no_add_attrs = true;
+    }
+  else
+    DECL_ATTRIBUTES (*node) 
+      = tree_cons (get_identifier ("stack_protect"),
+		   NULL_TREE, DECL_ATTRIBUTES (*node));
+
+  return NULL_TREE;
+}
+
 /* Handle a "noinline" attribute; arguments as in
    struct attribute_spec.handler.  */
 
diff --git a/gcc/c-family/c-cppbuiltin.c b/gcc/c-family/c-cppbuiltin.c
index 229a316..0b00d59 100644
--- a/gcc/c-family/c-cppbuiltin.c
+++ b/gcc/c-family/c-cppbuiltin.c
@@ -1212,6 +1212,8 @@ c_cpp_builtins (cpp_reader *pfile)
   /* Make the choice of the stack protector runtime visible to source code.
      The macro names and values here were chosen for compatibility with an
      earlier implementation, i.e. ProPolice.  */
+  if (flag_stack_protect == 4)
+    cpp_define (pfile, "__SSP_EXPLICIT__=4");
   if (flag_stack_protect == 3)
     cpp_define (pfile, "__SSP_STRONG__=3");
   if (flag_stack_protect == 2)
diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
index 8926e8f..c92c786 100644
--- a/gcc/cfgexpand.c
+++ b/gcc/cfgexpand.c
@@ -1411,7 +1411,8 @@ clear_tree_used (tree block)
 enum {
   SPCT_FLAG_DEFAULT = 1,
   SPCT_FLAG_ALL = 2,
-  SPCT_FLAG_STRONG = 3
+  SPCT_FLAG_STRONG = 3,
+  SPCT_FLAG_EXPLICIT = 4
 };
 
 /* Examine TYPE and determine a bit mask of the following features.  */
@@ -1484,7 +1485,10 @@ stack_protect_decl_phase (tree decl)
     has_short_buffer = true;
 
   if (flag_stack_protect == SPCT_FLAG_ALL
-      || flag_stack_protect == SPCT_FLAG_STRONG)
+      || flag_stack_protect == SPCT_FLAG_STRONG
+      || (flag_stack_protect == SPCT_FLAG_EXPLICIT
+	  && lookup_attribute ("stack_protect",
+			       DECL_ATTRIBUTES (current_function_decl))))
     {
       if ((bits & (SPCT_HAS_SMALL_CHAR_ARRAY | SPCT_HAS_LARGE_CHAR_ARRAY))
 	  && !(bits & SPCT_HAS_AGGREGATE))
@@ -1859,7 +1863,11 @@ expand_used_vars (void)
 
       /* If stack protection is enabled, we don't share space between
 	 vulnerable data and non-vulnerable data.  */
-      if (flag_stack_protect)
+      if (flag_stack_protect != 0
+	  && (flag_stack_protect != SPCT_FLAG_EXPLICIT
+	      || (flag_stack_protect == SPCT_FLAG_EXPLICIT
+		  && lookup_attribute ("stack_protect",
+				       DECL_ATTRIBUTES (current_function_decl)))))
 	add_stack_protection_conflicts ();
 
       /* Now that we have collected all stack variables, and have computed a
@@ -1877,15 +1885,24 @@ expand_used_vars (void)
 
     case SPCT_FLAG_STRONG:
       if (gen_stack_protect_signal
-	  || cfun->calls_alloca || has_protected_decls)
+	  || cfun->calls_alloca || has_protected_decls
+	  || lookup_attribute ("stack_protect",
+			       DECL_ATTRIBUTES (current_function_decl)))
 	create_stack_guard ();
       break;
 
     case SPCT_FLAG_DEFAULT:
-      if (cfun->calls_alloca || has_protected_decls)
+      if (cfun->calls_alloca || has_protected_decls
+	  || lookup_attribute ("stack_protect",
+			       DECL_ATTRIBUTES (current_function_decl)))
 	create_stack_guard ();
       break;
 
+    case SPCT_FLAG_EXPLICIT:
+      if (lookup_attribute ("stack_protect",
+			    DECL_ATTRIBUTES (current_function_decl)))
+	create_stack_guard ();
+      break;
     default:
       ;
     }
@@ -1911,7 +1928,11 @@ expand_used_vars (void)
 	  expand_stack_vars (stack_protect_decl_phase_1, &data);
 
 	  /* Phase 2 contains other kinds of arrays.  */
-	  if (flag_stack_protect == 2)
+	  if (flag_stack_protect == SPCT_FLAG_ALL
+	      || flag_stack_protect == SPCT_FLAG_STRONG
+	      || (flag_stack_protect == SPCT_FLAG_EXPLICIT
+		  && lookup_attribute ("stack_protect",
+				       DECL_ATTRIBUTES (current_function_decl))))
 	    expand_stack_vars (stack_protect_decl_phase_2, &data);
 	}
 
diff --git a/gcc/common.opt b/gcc/common.opt
index 3d19875..c321960 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -2093,6 +2093,10 @@ fstack-protector-strong
 Common Report RejectNegative Var(flag_stack_protect, 3)
 Use a smart stack protection method for certain functions
 
+fstack-protector-explicit
+Common Report RejectNegative Var(flag_stack_protect, 4)
+Use stack protection method only for functions with the stack_protect attribute
+
 fstack-usage
 Common RejectNegative Var(flag_stack_usage)
 Output stack usage information on a per-function basis
diff --git a/gcc/doc/cpp.texi b/gcc/doc/cpp.texi
index e94bdf7..10b72e7 100644
--- a/gcc/doc/cpp.texi
+++ b/gcc/doc/cpp.texi
@@ -2351,6 +2351,10 @@ in use.
 This macro is defined, with value 3, when @option{-fstack-protector-strong} is
 in use.
 
+@item __SSP_EXPLICIT__
+This macro is defined, with value 4, when @option{-fstack-protector-explicit} is
+in use.
+
 @item __SANITIZE_ADDRESS__
 This macro is defined, with value 1, when @option{-fsanitize=address}
 or @option{-fsanitize=kernel-address} are in use.
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 942a6bc..bf6d710 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -2207,7 +2207,7 @@ attributes are currently defined for functions on all targets:
 @code{no_sanitize_address}, @code{no_address_safety_analysis},
 @code{no_sanitize_thread},
 @code{no_sanitize_undefined}, @code{no_reorder}, @code{bnd_legacy},
-@code{bnd_instrument},
+@code{bnd_instrument}, @code{stack_protect},
 @code{error} and @code{warning}.
 Several other attributes are defined for functions on particular
 target systems.  Other attributes, including @code{section} are
@@ -3444,6 +3444,12 @@ prologue which decides whether to split the stack.  Functions with the
 @code{no_split_stack} attribute do not have that prologue, and thus
 may run with only a small amount of stack space available.
 
+@item stack_protect
+@cindex @code{stack_protect} function attribute
+This function attribute make a stack protection of the function if 
+flags @option{fstack-protector} or @option{fstack-protector-strong}
+or @option{fstack-protector-explicit} are set.
+
 @item noinline
 @cindex @code{noinline} function attribute
 This function attribute prevents a function from being considered for
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 748c70a..638ed9a 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -428,8 +428,9 @@ Objective-C and Objective-C++ Dialects}.
 -fsel-sched-pipelining -fsel-sched-pipelining-outer-loops @gol
 -fsemantic-interposition @gol
 -fshrink-wrap -fsignaling-nans -fsingle-precision-constant @gol
--fsplit-ivs-in-unroller -fsplit-wide-types -fssa-phiopt -fstack-protector @gol
--fstack-protector-all -fstack-protector-strong -fstrict-aliasing @gol
+-fsplit-ivs-in-unroller -fsplit-wide-types -fssa-phiopt @gol
+-fstack-protector -fstack-protector-all -fstack-protector-strong @gol
+-fstack-protector-explicit -fstrict-aliasing @gol
 -fstrict-overflow -fthread-jumps -ftracer -ftree-bit-ccp @gol
 -ftree-builtin-call-dce -ftree-ccp -ftree-ch @gol
 -ftree-coalesce-inline-vars -ftree-coalesce-vars -ftree-copy-prop @gol
@@ -9838,6 +9839,11 @@ Like @option{-fstack-protector} but includes additional functions to
 be protected --- those that have local array definitions, or have
 references to local frame addresses.
 
+@item -fstack-protector-explicit
+@opindex fstack-protector-explicit
+Like @option{-fstack-protector} but only protects those functions which
+have the @code{stack_protect} attribute
+
 @item -fsection-anchors
 @opindex fsection-anchors
 Try to reduce the number of symbolic address calculations by using
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 4be48a1..1c53160 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2015-01-14  Marcos Diaz <marcos.diaz@tallertechnologies.com>
+
+	* gcc.dg/stackprotectexplicit1.c: New test.
+	* g++.dg/stackprotectexplicit2.c: New test.
+
 2015-01-14  Jerry DeLisle  <jvdelisle@gcc.gnu.org>
 
 	PR target/61933
diff --git a/gcc/testsuite/g++.dg/stackprotectexplicit2.C b/gcc/testsuite/g++.dg/stackprotectexplicit2.C
new file mode 100644
index 0000000..9cf9ab9
--- /dev/null
+++ b/gcc/testsuite/g++.dg/stackprotectexplicit2.C
@@ -0,0 +1,27 @@
+/* Test that stack protection is done on chosen functions. */
+
+/* { dg-do compile { target i?86-*-* x86_64-*-* } } */
+/* { dg-options "-O2 -fstack-protector-explicit" } */
+
+int A()
+{
+	int A[23];
+	char b[22];
+}
+
+int __attribute__((stack_protect)) B()
+{
+	int a;
+	int b;
+	return a+b;
+}
+
+int __attribute__((stack_protect)) c()
+{
+	int a;
+	char b[34];
+	return 0;
+}
+
+
+/* { dg-final { scan-assembler-times "stack_chk_fail" 2 } } */
\ No newline at end of file
diff --git a/gcc/testsuite/gcc.dg/stackprotectexplicit1.c b/gcc/testsuite/gcc.dg/stackprotectexplicit1.c
new file mode 100644
index 0000000..658c297
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/stackprotectexplicit1.c
@@ -0,0 +1,23 @@
+/* { dg-do run { target native } } */
+/* { dg-options "-fstack-protector-explicit" } */
+/* { dg-require-effective-target fstack_protector } */
+
+#include <stdlib.h>
+
+void
+__stack_chk_fail (void)
+{
+  exit (0); /* pass */
+}
+
+int __attribute__((stack_protect)) main ()
+{
+  int i;
+  char foo[255];
+
+  // smash stack
+  for (i = 0; i <= 400; i++)
+    foo[i] = 42;
+
+  return 1; /* fail */
+}