[asan] Add __asan_set_shadow_*

[vitalybuka]

Summary

We are poisoning small allocas using store instruction from instrumented code.
For large allocas we'd like to insert function calls instead of multiple stores.

[vitalybuka]

clang format

[vitalybuka]

__asan_set_shadow_*

[vitalybuka]

Removed unchanged file

[eugenis]

LGTM

lib/asan/asan_interface_internal.h

extern "C" {
 
   // These two functions should be called before and after dynamic initializers
   // of a single module run, respectively.
   SANITIZER_INTERFACE_ATTRIBUTE
   void __asan_before_dynamic_init(const char *module_name);
   SANITIZER_INTERFACE_ATTRIBUTE
   void __asan_after_dynamic_init();
 
+  // Calls real memset with no mapping or checks.
+  SANITIZER_INTERFACE_ATTRIBUTE
+  void __asan_memset_real(uptr addr, u8 value, uptr size);
+
   // These two functions are used by instrumented code in the
   // use-after-scope mode. They mark memory for local variables as
   // unaddressable when they leave scope and addressable before the
   // function exits.
   SANITIZER_INTERFACE_ATTRIBUTE
   void __asan_poison_stack_memory(uptr addr, uptr size);
   SANITIZER_INTERFACE_ATTRIBUTE
   void __asan_unpoison_stack_memory(uptr addr, uptr size);

lib/asan/asan_poisoning.cc

static void PoisonAlignedStackMemory(uptr addr, uptr size, bool do_poison) {
   } else {
     // If necessary, mark few first bytes mapping to last shadow byte
     // as addressable
     if (end_value != 0)
       *shadow_end = Max(end_value, end_offset);
   }
 }
 
+void __asan_memset_real(uptr addr, u8 c, uptr size) {
+  REAL(memset)((void *)addr, c, size);
+}
+
 void __asan_poison_stack_memory(uptr addr, uptr size) {
   if (!__asan_option_detect_stack_use_after_scope) return;
   VReport(1, "poisoning: %p %zx\n", (void *)addr, size);
   PoisonAlignedStackMemory(addr, size, true);
 }
 
 void __asan_unpoison_stack_memory(uptr addr, uptr size) {
   if (!__asan_option_detect_stack_use_after_scope) return;

lib/asan/asan_rtl.cc

 // We want to keep those in the executable in order to let the instrumented
 // dynamic libraries access the symbol even if it is not used by the executable
 // itself. This should help if the build system is removing dead code at link
 // time.
 static NOINLINE void force_interface_symbols() {
   volatile int fake_condition = 0;  // prevent dead condition elimination.
   // __asan_report_* functions are noreturn, so we need a switch to prevent
   // the compiler from removing any of them.
+  // clang-format off
   switch (fake_condition) {
     case 1: __asan_report_load1(0); break;
     case 2: __asan_report_load2(0); break;
     case 3: __asan_report_load4(0); break;
     case 4: __asan_report_load8(0); break;
     case 5: __asan_report_load16(0); break;
     case 6: __asan_report_load_n(0, 0); break;
     case 7: __asan_report_store1(0); break;
switch (fake_condition) {
     case 31: __asan_poison_memory_region(nullptr, 0); break;
     case 32: __asan_unpoison_memory_region(nullptr, 0); break;
     case 34: __asan_before_dynamic_init(nullptr); break;
     case 35: __asan_after_dynamic_init(); break;
     case 36: __asan_poison_stack_memory(0, 0); break;
     case 37: __asan_unpoison_stack_memory(0, 0); break;
     case 38: __asan_region_is_poisoned(0, 0); break;
     case 39: __asan_describe_address(0); break;
+    case 40: __asan_memset_real(0, 0, 0); break;
   }
+  // clang-format on
 }
 
 static void asan_atexit() {
   Printf("AddressSanitizer exit stats:\n");
   __asan_print_accumulated_stats();
   // Print AsanMappingProfile.
   for (uptr i = 0; i < kAsanMappingProfileSize; i++) {
     if (AsanMappingProfile[i] == 0) continue;

lib/asan/asan_win_dll_thunk.cc

 INTERFACE_FUNCTION(__asan_load8)
 INTERFACE_FUNCTION(__asan_load16)
 INTERFACE_FUNCTION(__asan_loadN)
 
 INTERFACE_FUNCTION(__asan_memcpy);
 INTERFACE_FUNCTION(__asan_memset);
 INTERFACE_FUNCTION(__asan_memmove);
 
+INTERFACE_FUNCTION(__asan_memset_real);
+
 INTERFACE_FUNCTION(__asan_alloca_poison);
 INTERFACE_FUNCTION(__asan_allocas_unpoison);
 
 INTERFACE_FUNCTION(__asan_register_globals)
 INTERFACE_FUNCTION(__asan_unregister_globals)
 
 INTERFACE_FUNCTION(__asan_before_dynamic_init)
 INTERFACE_FUNCTION(__asan_after_dynamic_init)