Implement protection of stack variables

This patch implements the protection of stack variables.

It lays out stack variables as well as the different red zones,
emits some prologue code to populate the shadow memory as to poison
(mark as non-accessible) the regions of the red zones and mark the
regions of stack variables as accessible, and emit some epilogue code
to un-poison (mark as accessible) the regions of red zones right
before the function exits.

	* Makefile.in (asan.o): Depend on $(EXPR_H) $(OPTABS_H).
	(cfgexpand.o): Depend on asan.h.
	* asan.c: Include expr.h and optabs.h.
	(asan_shadow_set): New variable.
	(asan_shadow_cst, asan_emit_stack_protection): New functions.
	(asan_init_shadow_ptr_types): Initialize also asan_shadow_set.
	* cfgexpand.c: Include asan.h.  Define HOST_WIDE_INT heap vector.
	(partition_stack_vars): If i is large alignment and j small
	alignment or vice versa, break out of the loop instead of continue,
	and put the test earlier.  If flag_asan, break out of the loop
	if for small alignment size is different.
	(struct stack_vars_data): New type.
	(expand_stack_vars): Add DATA argument.  Change PRED type to
	function taking size_t argument instead of tree.  Adjust pred
	calls.  Fill DATA in and add needed padding in between variables
	if -faddress-sanitizer.
	(defer_stack_allocation): Defer everything for flag_asan.
	(stack_protect_decl_phase_1, stack_protect_decl_phase_2): Take
	size_t index into stack_vars array instead of the decl directly.
	(asan_decl_phase_3): New function.
	(expand_used_vars): Return var destruction sequence.  Adjust
	expand_stack_vars calls, add another one for flag_asan.  Call
	asan_emit_stack_protection if expand_stack_vars added anything
	to the vectors.
	(expand_gimple_basic_block): Add disable_tail_calls argument.
	(gimple_expand_cfg): Pass true to it if expand_used_vars returned
	non-NULL.  Emit the sequence returned by expand_used_vars after
	return_label.
	* asan.h (asan_emit_stack_protection): New prototype.
	(asan_shadow_set): New decl.
	(ASAN_RED_ZONE_SIZE, ASAN_STACK_MAGIC_LEFT, ASAN_STACK_MAGIC_MIDDLE,
	ASAN_STACK_MAGIC_RIGHT, ASAN_STACK_FRAME_MAGIC): Define.
	(asan_protect_stack_decl): New inline.
	* toplev.c (process_options): Also disable -faddress-sanitizer on
	!FRAME_GROWS_DOWNWARDS targets.

From-SVN: r193436

1 files changed, 30 insertions, 1 deletions

diff --git a/gcc/asan.h b/gcc/asan.h
index 0d9ab8b77a6..6f0edbf27b2 100644
--- a/gcc/asan.h
+++ b/gcc/asan.h
@@ -21,10 +21,39 @@ along with GCC; see the file COPYING3.  If not see
 #ifndef TREE_ASAN
 #define TREE_ASAN
 
-extern void asan_finish_file(void);
+extern void asan_finish_file (void);
+extern rtx asan_emit_stack_protection (rtx, HOST_WIDE_INT *, tree *, int);
+
+/* Alias set for accessing the shadow memory.  */
+extern alias_set_type asan_shadow_set;
 
 /* Shadow memory is found at
    (address >> ASAN_SHADOW_SHIFT) + targetm.asan_shadow_offset ().  */
 #define ASAN_SHADOW_SHIFT	3
 
+/* Red zone size, stack and global variables are padded by ASAN_RED_ZONE_SIZE
+   up to 2 * ASAN_RED_ZONE_SIZE - 1 bytes.  */
+#define ASAN_RED_ZONE_SIZE	32
+
+/* Shadow memory values for stack protection.  Left is below protected vars,
+   the first pointer in stack corresponding to that offset contains
+   ASAN_STACK_FRAME_MAGIC word, the second pointer to a string describing
+   the frame.  Middle is for padding in between variables, right is
+   above the last protected variable and partial immediately after variables
+   up to ASAN_RED_ZONE_SIZE alignment.  */
+#define ASAN_STACK_MAGIC_LEFT		0xf1
+#define ASAN_STACK_MAGIC_MIDDLE		0xf2
+#define ASAN_STACK_MAGIC_RIGHT		0xf3
+#define ASAN_STACK_MAGIC_PARTIAL	0xf4
+
+#define ASAN_STACK_FRAME_MAGIC	0x41b58ab3
+
+/* Return true if DECL should be guarded on the stack.  */
+
+static inline bool
+asan_protect_stack_decl (tree decl)
+{
+  return DECL_P (decl) && !DECL_ARTIFICIAL (decl);
+}
+
 #endif /* TREE_ASAN */