[PATCH] Provide global var location info for asan

[Jakub Jelinek <jakub at redhat dot com>]

On Tue, Sep 23, 2014 at 11:03:55AM -0700, Konstantin Serebryany wrote:
> >>         (asan_add_global): Ditto.
> >
> > I'll handle creation of location aggregates as follow-up.

Here it is, only lightly tested so far:

int a = 1;
int b = 2;
int c = 3;

int *
foo (int x)
{
  return x ? &b : &c;
}

int
main ()
{
  char *p = (char *) foo (1);
  int x = p[sizeof (int)];
  asm ("" : : "r" (x));
  return 0;
}

used to print:
0x000000601104 is located 60 bytes to the left of global variable 'a' defined in 'aa.c' (0x601140) of size 4
0x000000601104 is located 0 bytes to the right of global variable 'b' defined in 'aa.c' (0x601100) of size 4
but now does:
0x000000601104 is located 60 bytes to the left of global variable 'a' defined in 'aa.c:1:5' (0x601140) of size 4
0x000000601104 is located 0 bytes to the right of global variable 'b' defined in 'aa.c:2:5' (0x601100) of size 4

I think this test is too fragile for the testsuite though, the order of the
vars in the data section can be arbitrary etc.
make -j16 -k check-gcc check-g++ check-gfortran RUNTESTFLAGS='--target_board=unix\{-m32,-m64\} asan.exp'
passed.

For Marek: the patch also uses just one __ubsan_source_location
RECORD_TYPE everywhere, I've been really surprised we created a new type
node each time we needed it.

Ok for trunk?

2014-09-24  Jakub Jelinek  <jakub@redhat.com>

	* ubsan.h (ubsan_get_source_location): New prototype.
	* ubsan.c (ubsan_source_location_type): New variable.
	Function renamed to ...
	(ubsan_get_source_location_type): ... this.  Cache
	return value in ubsan_source_location_type variable.
	(ubsan_source_location, ubsan_create_data): Use
	ubsan_get_source_location_type instead of
	ubsan_source_location_type.
	* asan.c (asan_protect_global): Don't protect globals
	with ubsan_get_source_location_type () type.
	(asan_add_global): Provide global decl location info
	if possible.

--- gcc/ubsan.h.jj	2014-09-24 08:26:49.635418299 +0200
+++ gcc/ubsan.h	2014-09-24 11:35:05.231330166 +0200
@@ -47,6 +47,6 @@ extern tree ubsan_encode_value (tree, bo
 extern bool is_ubsan_builtin_p (tree);
 extern tree ubsan_build_overflow_builtin (tree_code, location_t, tree, tree, tree);
 extern tree ubsan_instrument_float_cast (location_t, tree, tree);
+extern tree ubsan_get_source_location_type (void);
 
 #endif  /* GCC_UBSAN_H  */
-
--- gcc/ubsan.c.jj	2014-09-24 08:26:49.639418278 +0200
+++ gcc/ubsan.c	2014-09-24 11:35:56.662054997 +0200
@@ -197,6 +197,9 @@ ubsan_type_descriptor_type (void)
   return ret;
 }
 
+/* Cached ubsan_get_source_location_type () return value.  */
+static GTY(()) tree ubsan_source_location_type;
+
 /* Build
    struct __ubsan_source_location
    {
@@ -206,12 +209,15 @@ ubsan_type_descriptor_type (void)
    }
    type.  */
 
-static tree
-ubsan_source_location_type (void)
+tree
+ubsan_get_source_location_type (void)
 {
   static const char *field_names[3]
     = { "__filename", "__line", "__column" };
   tree fields[3], ret;
+  if (ubsan_source_location_type)
+    return ubsan_source_location_type;
+
   tree const_char_type = build_qualified_type (char_type_node,
 					       TYPE_QUAL_CONST);
 
@@ -229,6 +235,7 @@ ubsan_source_location_type (void)
   TYPE_FIELDS (ret) = fields[0];
   TYPE_NAME (ret) = get_identifier ("__ubsan_source_location");
   layout_type (ret);
+  ubsan_source_location_type = ret;
   return ret;
 }
 
@@ -239,7 +246,7 @@ static tree
 ubsan_source_location (location_t loc)
 {
   expanded_location xloc;
-  tree type = ubsan_source_location_type ();
+  tree type = ubsan_get_source_location_type ();
 
   xloc = expand_location (loc);
   tree str;
@@ -484,7 +491,7 @@ ubsan_create_data (const char *name, int
     {
       gcc_checking_assert (i < 2);
       fields[i] = build_decl (UNKNOWN_LOCATION, FIELD_DECL, NULL_TREE,
-			      ubsan_source_location_type ());
+			      ubsan_get_source_location_type ());
       DECL_CONTEXT (fields[i]) = ret;
       if (i)
 	DECL_CHAIN (fields[i - 1]) = fields[i];
--- gcc/asan.c.jj	2014-09-24 11:13:43.548211574 +0200
+++ gcc/asan.c	2014-09-24 12:06:13.122500445 +0200
@@ -1316,7 +1316,8 @@ asan_protect_global (tree decl)
       || DECL_SIZE (decl) == 0
       || ASAN_RED_ZONE_SIZE * BITS_PER_UNIT > MAX_OFILE_ALIGNMENT
       || !valid_constant_size_p (DECL_SIZE_UNIT (decl))
-      || DECL_ALIGN_UNIT (decl) > 2 * ASAN_RED_ZONE_SIZE)
+      || DECL_ALIGN_UNIT (decl) > 2 * ASAN_RED_ZONE_SIZE
+      || TREE_TYPE (decl) == ubsan_get_source_location_type ())
     return false;
 
   rtl = DECL_RTL (decl);
@@ -2224,8 +2225,38 @@ asan_add_global (tree decl, tree type, v
   int has_dynamic_init = vnode ? vnode->dynamically_initialized : 0;
   CONSTRUCTOR_APPEND_ELT (vinner, NULL_TREE,
 			  build_int_cst (uptr, has_dynamic_init));
-  CONSTRUCTOR_APPEND_ELT (vinner, NULL_TREE,
-			  build_int_cst (uptr, 0));
+  tree locptr = NULL_TREE;
+  location_t loc = DECL_SOURCE_LOCATION (decl);
+  expanded_location xloc = expand_location (loc);
+  if (xloc.file != NULL)
+    {
+      static int lasanloccnt = 0;
+      char buf[25];
+      ASM_GENERATE_INTERNAL_LABEL (buf, "LASANLOC", ++lasanloccnt);
+      tree var = build_decl (UNKNOWN_LOCATION, VAR_DECL, get_identifier (buf),
+			     ubsan_get_source_location_type ());
+      TREE_STATIC (var) = 1;
+      TREE_PUBLIC (var) = 0;
+      DECL_ARTIFICIAL (var) = 1;
+      DECL_IGNORED_P (var) = 1;
+      pretty_printer filename_pp;
+      pp_string (&filename_pp, xloc.file);
+      tree str = asan_pp_string (&filename_pp);
+      tree ctor = build_constructor_va (TREE_TYPE (var), 3,
+					NULL_TREE, str, NULL_TREE,
+					build_int_cst (unsigned_type_node,
+						       xloc.line), NULL_TREE,
+					build_int_cst (unsigned_type_node,
+						       xloc.column));
+      TREE_CONSTANT (ctor) = 1;
+      TREE_STATIC (ctor) = 1;
+      DECL_INITIAL (var) = ctor;
+      varpool_node::finalize_decl (var);
+      locptr = fold_convert (uptr, build_fold_addr_expr (var));
+    }
+  else
+    locptr = build_int_cst (uptr, 0);
+  CONSTRUCTOR_APPEND_ELT (vinner, NULL_TREE, locptr);
   init = build_constructor (type, vinner);
   CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, init);
 }


	Jakub