RFC Asan instrumentation control

2013-12-18  Max Ostapenko  <m.ostapenko@partner.samsung.com>

	* gcc/asan.c (asan_emit_stack_protection): Optionally disable stack protection.
	(instrument_derefs): Optionally disable memory access instrumentation.
	(instrument_mem_region_access): Likewise.
	(instrument_strlen_call): Likewise.
	(asan_finish_file): Optionally disable global variables protection.
	* gcc/doc/invoke.texi: Added doc for new options.
	* gcc/params.def: Added new options.
	* gcc/params.h: Likewise.

2013-12-18  Max Ostapenko  <m.ostapenko@partner.samsung.com>
	* c-c++-common/asan/global-overflow-2.c: New test.
	* c-c++-common/asan/memcmp-3.c: Likewise.
	* c-c++-common/asan/no-instrument-reads.c: Likewise.
	* c-c++-common/asan/no-instrument-writes.c: Likewise.

diff --git a/gcc/asan.c b/gcc/asan.c
index 1394e13..1b8d0c2 100644
--- a/gcc/asan.c
+++ b/gcc/asan.c
@@ -53,6 +53,7 @@  along with GCC; see the file COPYING3.  If not see
 #include "gimple-builder.h"
 #include "ubsan.h"
 #include "predict.h"
+#include "params.h"
 
 /* AddressSanitizer finds out-of-bounds and use-after-free bugs
    with <2x slowdown on average.
@@ -963,6 +964,9 @@  rtx
 asan_emit_stack_protection (rtx base, rtx pbase, unsigned int alignb,
 			    HOST_WIDE_INT *offsets, tree *decls, int length)
 {
+  if (!ASAN_STACK)
+    return NULL_RTX;
+
   rtx shadow_base, shadow_mem, ret, mem, orig_base, lab;
   char buf[30];
   unsigned char shadow_bytes[4];
@@ -1568,6 +1572,11 @@  static void
 instrument_derefs (gimple_stmt_iterator *iter, tree t,
 		   location_t location, bool is_store)
 {
+  if (is_store && !ASAN_INSTRUMENT_WRITES)
+    return;
+  if (!is_store && !ASAN_INSTRUMENT_READS)
+    return;
+
   tree type, base;
   HOST_WIDE_INT size_in_bytes;
 
@@ -1662,6 +1671,11 @@  instrument_mem_region_access (tree base, tree len,
 			      gimple_stmt_iterator *iter,
 			      location_t location, bool is_store)
 {
+  if (is_store && !ASAN_INSTRUMENT_WRITES)
+    return;
+  if (!is_store && !ASAN_INSTRUMENT_READS)
+    return;
+
   if (!POINTER_TYPE_P (TREE_TYPE (base))
       || !INTEGRAL_TYPE_P (TREE_TYPE (len))
       || integer_zerop (len))
@@ -1825,6 +1839,9 @@  instrument_mem_region_access (tree base, tree len,
 static bool
 instrument_strlen_call (gimple_stmt_iterator *iter)
 {
+  if (!ASAN_INSTRUMENT_READS)
+    return false;
+
   gimple call = gsi_stmt (*iter);
   gcc_assert (is_gimple_call (call));
 
@@ -2396,7 +2413,7 @@  asan_finish_file (void)
       ++gcount;
   htab_t const_desc_htab = constant_pool_htab ();
   htab_traverse (const_desc_htab, count_string_csts, &gcount);
-  if (gcount)
+  if (gcount && ASAN_GLOBALS)
     {
       tree type = asan_global_struct (), var, ctor;
       tree dtor_statements = NULL_TREE;
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 99ec1d2..d1f20a9 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -10037,6 +10037,26 @@  The default choice depends on the target.
 Set the maximum number of existing candidates that will be considered when
 seeking a basis for a new straight-line strength reduction candidate.
 
+@item asan-globals
+Enable overflow/underflow detection for global objects. This kind of protection
+is enabled by default if you are using @option{-fsanitize=address} option.
+To disable global objects protection use @option{--param asan-globals=0} option.
+
+@item asan-stack
+Enable overflow/underflow detection for stack objects. This kind of protection
+is enabled by default if you are using @option{-fsanitize=address} option.
+To disable stack protection use @option{--param asan-stack=0} option.
+
+@item asan-instrument-reads
+Enable overflow/underflow detection for memory reads instructions. This kind of protection
+is enabled by default if you are using @option{-fsanitize=address} option.
+To disable memory reads instructions protection use @option{--param asan-instrument-reads=0} option.
+
+@item asan-instrument-writes
+Enable overflow/underflow detection for memory writes instructions. This kind of protection
+is enabled by default if you are using @option{-fsanitize=address} option.
+To disable memory writes instructions protection use @option{--param asan-instrument-writes=0} option.
+
 @end table
 @end table
 
diff --git a/gcc/params.def b/gcc/params.def
index c0f9622..aea5f41 100644
--- a/gcc/params.def
+++ b/gcc/params.def
@@ -1049,6 +1049,26 @@  DEFPARAM (PARAM_MAX_SLSR_CANDIDATE_SCAN,
 	  "strength reduction",
 	  50, 1, 999999)
 
+DEFPARAM(PARAM_ASAN_STACK,
+         "asan-stack",
+         "Enable asan stack protection",
+         1, 0, 1)
+
+DEFPARAM(PARAM_ASAN_GLOBALS,
+         "asan-globals",
+         "Enable asan globals protection",
+         1, 0, 1)
+
+DEFPARAM(PARAM_ASAN_INSTRUMENT_WRITES,
+         "asan-instrument-writes",
+         "Enable asan store operations protection",
+         1, 0, 1)
+
+DEFPARAM(PARAM_ASAN_INSTRUMENT_READS,
+         "asan-instrument-reads",
+         "Enable asan load operations protection",
+         1, 0, 1)
+
 /*
 Local variables:
 mode:c
diff --git a/gcc/params.h b/gcc/params.h
index f137e9e..bbc2929 100644
--- a/gcc/params.h
+++ b/gcc/params.h
@@ -218,5 +218,14 @@  extern void init_param_values (int *params);
   PARAM_VALUE (PARAM_ALLOW_PACKED_LOAD_DATA_RACES)
 #define ALLOW_PACKED_STORE_DATA_RACES \
   PARAM_VALUE (PARAM_ALLOW_PACKED_STORE_DATA_RACES)
+#define ASAN_STACK \
+  PARAM_VALUE (PARAM_ASAN_STACK)
+#define ASAN_GLOBALS \
+  PARAM_VALUE (PARAM_ASAN_GLOBALS)
+#define ASAN_INSTRUMENT_READS \
+  PARAM_VALUE (PARAM_ASAN_INSTRUMENT_READS)
+#define ASAN_INSTRUMENT_WRITES \
+  PARAM_VALUE (PARAM_ASAN_INSTRUMENT_WRITES)
+
 
 #endif /* ! GCC_PARAMS_H */
diff --git a/gcc/testsuite/c-c++-common/asan/global-overflow-2.c b/gcc/testsuite/c-c++-common/asan/global-overflow-2.c
new file mode 100644
index 0000000..5fe7ba3
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/asan/global-overflow-2.c
@@ -0,0 +1,22 @@ 
+/* { dg-do run } */
+/* { dg-options "--param asan-globals=0" } */
+#include <stdio.h>
+extern
+#ifdef __cplusplus
+"C"
+#endif
+void *memset (void *, int, __SIZE_TYPE__);
+
+volatile int ten = 10;
+
+int main() {
+  static char XXX[10];
+  static char YYY[10];
+  static char ZZZ[10];
+  memset(XXX, 0, 10);
+  memset(YYY, 0, 10);
+  memset(ZZZ, 0, 10);
+  int res = YYY[ten];  /* BOOOM */
+  res += XXX[ten/10] + ZZZ[ten/10];
+  return 0;
+}
diff --git a/gcc/testsuite/c-c++-common/asan/memcmp-3.c b/gcc/testsuite/c-c++-common/asan/memcmp-3.c
new file mode 100644
index 0000000..2f50939
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/asan/memcmp-3.c
@@ -0,0 +1,14 @@ 
+/* { dg-do run } */
+/* { dg-options "--param asan-stack=0" } */
+#include <string.h>
+
+volatile int one = 1;
+
+int
+main ()
+{
+  char a1[] = {one, 2, 3, 4};
+  char a2[] = {1, 2*one, 3, 4};
+  int res = memcmp (a1, a2, 5 + one);
+  return 0;
+}
diff --git a/gcc/testsuite/c-c++-common/asan/no-instrument-reads.c b/gcc/testsuite/c-c++-common/asan/no-instrument-reads.c
new file mode 100644
index 0000000..6098545
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/asan/no-instrument-reads.c
@@ -0,0 +1,18 @@ 
+/* { dg-do run } */
+/* { dg-options "--param asan-instrument-reads=0" } */
+
+extern
+#ifdef __cplusplus
+"C"
+#endif
+void *memset (void *, int, __SIZE_TYPE__);
+
+volatile int ten = 10;
+
+int main() {
+  volatile char x[10];
+  memset((void*) x, 0, 10);
+  volatile int a = x[ten];  /* BOOOM */
+  return 0;
+}
+
diff --git a/gcc/testsuite/c-c++-common/asan/no-instrument-writes.c b/gcc/testsuite/c-c++-common/asan/no-instrument-writes.c
new file mode 100644
index 0000000..2569f39
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/asan/no-instrument-writes.c
@@ -0,0 +1,19 @@ 
+/* { dg-do run } */
+/* { dg-options "--param asan-instrument-writes=0" } */
+
+extern
+#ifdef __cplusplus
+"C"
+#endif
+void *memset (void *, int, __SIZE_TYPE__);
+
+volatile int ten = 10;
+
+int main() {
+  volatile char x[10];
+  volatile int y;
+  memset((void *)x, 0, 10);
+  x[ten] = 1;  /* BOOOM */
+  return 0;
+}
+