Implement protection of global variables

This patch implements the protection of global variables.  See the
comments appended to the beginning of the asan.c file.

	* varasm.c: Include asan.h.
	(assemble_noswitch_variable): Grow size by asan_red_zone_size
	if decl is asan protected.
	(place_block_symbol): Likewise.
	(assemble_variable): If decl is asan protected, increase
	DECL_ALIGN if needed, and for decls emitted using
	assemble_variable_contents append padding zeros after it.
	* Makefile.in (varasm.o): Depend on asan.h.
	* asan.c: Include output.h.
	(asan_pp, asan_pp_initialized, asan_ctor_statements): New variables.
	(asan_pp_initialize, asan_pp_string): New functions.
	(asan_emit_stack_protection): Use asan_pp{,_initialized}
	instead of local pp{,_initialized} vars, use asan_pp_initialize
	and asan_pp_string helpers.
	(asan_needs_local_alias, asan_protect_global,
	asan_global_struct, asan_add_global): New functions.
	(asan_finish_file): Protect global vars that can be protected. Use
	asan_ctor_statements instead of ctor_statements
	* asan.h (asan_protect_global): New prototype.
	(asan_red_zone_size): New inline function.

Co-Authored-By: Wei Mi <wmi@google.com>

From-SVN: r193437

gcc/ChangeLog

 2012-11-12  Jakub Jelinek  <jakub@redhat.com>
+	    Wei Mi <wmi@google.com>
+
+	* varasm.c: Include asan.h.
+	(assemble_noswitch_variable): Grow size by asan_red_zone_size
+	if decl is asan protected.
+	(place_block_symbol): Likewise.
+	(assemble_variable): If decl is asan protected, increase
+	DECL_ALIGN if needed, and for decls emitted using
+	assemble_variable_contents append padding zeros after it.
+	* Makefile.in (varasm.o): Depend on asan.h.
+	* asan.c: Include output.h.
+	(asan_pp, asan_pp_initialized, asan_ctor_statements): New variables.
+	(asan_pp_initialize, asan_pp_string): New functions.
+	(asan_emit_stack_protection): Use asan_pp{,_initialized}
+	instead of local pp{,_initialized} vars, use asan_pp_initialize
+	and asan_pp_string helpers.
+	(asan_needs_local_alias, asan_protect_global,
+	asan_global_struct, asan_add_global): New functions.
+	(asan_finish_file): Protect global vars that can be protected. Use
+	asan_ctor_statements instead of ctor_statements
+	* asan.h (asan_protect_global): New prototype.
+	(asan_red_zone_size): New inline function.
+
+2012-11-12  Jakub Jelinek  <jakub@redhat.com>
 
 	* Makefile.in (asan.o): Depend on $(EXPR_H) $(OPTABS_H).
 	(cfgexpand.o): Depend on asan.h.

gcc/Makefile.in

@@ -2719,7 +2719,7 @@ varasm.o : varasm.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(TREE_H) \
    output.h $(DIAGNOSTIC_CORE_H) xcoffout.h debug.h $(GGC_H) $(TM_P_H) \
    $(HASHTAB_H) $(TARGET_H) langhooks.h gt-varasm.h $(BASIC_BLOCK_H) \
    $(CGRAPH_H) $(TARGET_DEF_H) tree-mudflap.h \
-   pointer-set.h $(COMMON_TARGET_H)
+   pointer-set.h $(COMMON_TARGET_H) asan.h
 function.o : function.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(RTL_ERROR_H) \
    $(TREE_H) $(GIMPLE_H) $(FLAGS_H) $(FUNCTION_H) $(EXPR_H) \
    $(OPTABS_H) $(LIBFUNCS_H) $(REGS_H) hard-reg-set.h insn-config.h $(RECOG_H) \

gcc/asan.h

@@ -23,6 +23,7 @@ along with GCC; see the file COPYING3.  If not see
 
 extern void asan_finish_file (void);
 extern rtx asan_emit_stack_protection (rtx, HOST_WIDE_INT *, tree *, int);
+extern bool asan_protect_global (tree);
 
 /* Alias set for accessing the shadow memory.  */
 extern alias_set_type asan_shadow_set;
@@ -56,4 +57,14 @@ asan_protect_stack_decl (tree decl)
   return DECL_P (decl) && !DECL_ARTIFICIAL (decl);
 }
 
+/* Return the size of padding needed to insert after a protected
+   decl of SIZE.  */
+
+static inline unsigned int
+asan_red_zone_size (unsigned int size)
+{
+  unsigned int c = size & (ASAN_RED_ZONE_SIZE - 1);
+  return c ? 2 * ASAN_RED_ZONE_SIZE - c : ASAN_RED_ZONE_SIZE;
+}
+
 #endif /* TREE_ASAN */

gcc/varasm.c

@@ -51,6 +51,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "tree-mudflap.h"
 #include "cgraph.h"
 #include "pointer-set.h"
+#include "asan.h"
 
 #ifdef XCOFF_DEBUGGING_INFO
 #include "xcoffout.h"		/* Needed for external data
@@ -1831,6 +1832,9 @@ assemble_noswitch_variable (tree decl, const char *name, section *sect)
   size = tree_low_cst (DECL_SIZE_UNIT (decl), 1);
   rounded = size;
 
+  if (flag_asan && asan_protect_global (decl))
+    size += asan_red_zone_size (size);
+
   /* Don't allocate zero bytes of common,
      since that means "undefined external" in the linker.  */
   if (size == 0)
@@ -1897,6 +1901,7 @@ assemble_variable (tree decl, int top_level ATTRIBUTE_UNUSED,
   const char *name;
   rtx decl_rtl, symbol;
   section *sect;
+  bool asan_protected = false;
 
   /* This function is supposed to handle VARIABLES.  Ensure we have one.  */
   gcc_assert (TREE_CODE (decl) == VAR_DECL);
@@ -1984,6 +1989,15 @@ assemble_variable (tree decl, int top_level ATTRIBUTE_UNUSED,
   /* Compute the alignment of this data.  */
 
   align_variable (decl, dont_output_data);
+
+  if (flag_asan
+      && asan_protect_global (decl))
+    {
+      asan_protected = true;
+      DECL_ALIGN (decl) = MAX (DECL_ALIGN (decl), 
+                               ASAN_RED_ZONE_SIZE * BITS_PER_UNIT);
+    }
+
   set_mem_align (decl_rtl, DECL_ALIGN (decl));
 
   if (TREE_PUBLIC (decl))
@@ -2022,6 +2036,12 @@ assemble_variable (tree decl, int top_level ATTRIBUTE_UNUSED,
       if (DECL_ALIGN (decl) > BITS_PER_UNIT)
 	ASM_OUTPUT_ALIGN (asm_out_file, floor_log2 (DECL_ALIGN_UNIT (decl)));
       assemble_variable_contents (decl, name, dont_output_data);
+      if (asan_protected)
+	{
+	  unsigned HOST_WIDE_INT int size
+	    = tree_low_cst (DECL_SIZE_UNIT (decl), 1);
+	  assemble_zeros (asan_red_zone_size (size));
+	}
     }
 }
 
@@ -6926,6 +6946,8 @@ place_block_symbol (rtx symbol)
       decl = SYMBOL_REF_DECL (symbol);
       alignment = DECL_ALIGN (decl);
       size = tree_low_cst (DECL_SIZE_UNIT (decl), 1);
+      if (flag_asan && asan_protect_global (decl))
+	size += asan_red_zone_size (size);
     }
 
   /* Calculate the object's offset from the start of the block.  */