[asan] Add exception handler to map memory on demand on Win64.

[wang0109]

Summary

[asan] Add exception handler to map memory on demand on Win64.
Memory will be committed on demand when exception happens while accessing
shadow memeory region.

[etienneb]

lib/asan/asan_win.cc

227

Does this can be done into: InitializeExceptionHandlerOnWindows64

244

no { } here

265

'auto' here won't comply with the common coding style in llvm.
The type is not on the rhs, so use char* instead.

271

ditto 'auto'

280

rewrite the following list has a single line.

if (AddVectoredExceptionHandler(TRUE, &ShadowExceptionHandler) != nullptr)

or

if (!AddVectoredExceptionHandler(TRUE, &ShadowExceptionHandler))

[wang0109]

• update diff: format and minor styling

[etienneb]

lib/asan/asan_win.cc

257

As I get it, for the shadow memory this should never happens???
The whole memory space used by the shadow must be already reserved.

[etienneb]

lib/asan/asan_internal.h

65

I'm not a fan of these #ifdef

Should we use something similar than: void InitializePlatformInterceptors();
but for the shadow.

[wang0109]

lib/asan/asan_internal.h

65

Sounds reasonable. Could be called InitializePlatformExceptionHandlers() ?

[wang0109]

• update diff: remove several ifdefs, rename to InitializePlatformExceptionHandlers

[rnk]

lib/asan/asan_win.cc

223–231

Use GetPageSizeCached() and GetMmapGranularity() instead.

249–250

Use RoundDownTo instead of the bitmath

257

Yeah, what's the story here? We're going with up-front reservation first, and that succeeds in Win8.1+, right?

260–261

RoundDownTo

[wang0109]

• update diff: cleanup code regarding RoundDownTo, GetPageSize

[• chrisha]

lib/asan/asan_win.cc

257

This is cut and paste from a small test harness I wrote. Because of the page table overhead on Win7, I was tinkering with not even reserving the shadow at all, and had added this support. I think it simpler if we just say only Win8+ is recommended for x64, and document the page table overhead for Win7. This is better than the potential correctness problem that can result if somebody else gets memory where we think we have the shadow.

[wang0109]

lib/asan/asan_win.cc

257

Yes. This piece of code was ported from a test program (credits to chrisha). I thought for a while and it should be not useful in the case of windows 10, apart from being defensive code. For window 7, I am not quite sure what's the behavior. One thing that I would like to test is, VirtualAlloc() seems to have alignment requirement of allocation granularity for any flag involving MEM_RESERVE, if I understand correctly. For MEM_COMMIT only flag, address only have to be aligned with page size.

[wang0109]

• update diff: remove unneeded code, avoid commit limit error 1455

[etienneb]

drive-by

lib/asan/asan_win.cc

262

Change this for a CHECK(...)

lib/sanitizer_common/sanitizer_win.cc

171 ↗

(On Diff #63446)

IIRC, this function is used at other place. (MmapFixedNoReserve).
We should probably do a variant of that fonction, showing the "on-demand" behavior in the name.

178 ↗

(On Diff #63446)

nit: execption -> exeception

[wang0109]

• update diff: fix typo, use CHECK() to replace __debugbreak

[wang0109]

lib/sanitizer_common/sanitizer_win.cc

171 ↗

(On Diff #63447)

I see, this function also used in dfsan, esan etc. The name is already confusing.. It says "NoReserve" yet we are passing MEM_RESERVE flag..

[rnk]

lgtm

lib/sanitizer_common/sanitizer_win.cc

171 ↗

(On Diff #63447)

The name reflects the flags that you would pass to mmap on unix.

178 ↗

(On Diff #63447)

still need to fix this

[wang0109]

• update diff: fix typo

[etienneb]

This CL is not compiling.
Please fix:

../llvm/llvm/projects/compiler-rt/lib/asan/asan_win.cc:232:  Lines should be <= 80 characters long  [whitespace/line_length] [2]
../llvm/llvm/projects/compiler-rt/lib/asan/asan_win.cc:249:  Lines should be <= 80 characters long  [whitespace/line_length] [2]

and this

projects/compiler-rt/lib/asan/CMakeFiles/RTAsan_dynamic.x86_64.dir/asan_rtl.cc.o: In function `AsanInitInternal':
/usr/local/google/home/etienneb/llvm/llvm/projects/compiler-rt/lib/asan/asan_rtl.cc:423: undefined reference to `__asan::InitializePlatformExceptionHandlers()'
collect2: error: ld returned 1 exit status

[wang0109]

• update diff: fix compile for linux/mac
• update diff: coding style

[dvyukov]

FYI, this broke tsan. Only asan installs vectored SEH handler. I fixed it in:
http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_win.cc?r1=276112&r2=276111&pathrev=276112

lib/asan/asan_internal.h

 // functions from the instrumented user code in a profile.
 namespace __asan {
 
 class AsanThread;
 using __sanitizer::StackTrace;
 
 void AsanInitFromRtl();
 
+// asan_win.cc
+void InitializePlatformExceptionHandlers();
+
 // asan_rtl.cc
 void NORETURN ShowStatsAndAbort();
 
 // asan_malloc_linux.cc / asan_malloc_mac.cc
 void ReplaceSystemMalloc();
 
 // asan_linux.cc / asan_mac.cc / asan_win.cc
 void *AsanDoesNotSupportStaticLinkage();
#define ASAN_FREE_HOOK(ptr)                                 \
   } while (false)
 #define ASAN_ON_ERROR() \
   if (&__asan_on_error) __asan_on_error()
 
 extern int asan_inited;
 // Used to avoid infinite recursion in __asan_init().
 extern bool asan_init_is_running;
 extern void (*death_callback)(void);
-
 // These magic values are written to shadow for better error reporting.
 const int kAsanHeapLeftRedzoneMagic = 0xfa;
 const int kAsanHeapRightRedzoneMagic = 0xfb;
 const int kAsanHeapFreeMagic = 0xfd;
 const int kAsanStackLeftRedzoneMagic = 0xf1;
 const int kAsanStackMidRedzoneMagic = 0xf2;
 const int kAsanStackRightRedzoneMagic = 0xf3;
 const int kAsanStackPartialRedzoneMagic = 0xf4;

lib/asan/asan_rtl.cc

static void AsanInitInternal() {
 
   AsanCheckIncompatibleRT();
   AsanCheckDynamicRTPrereqs();
   AvoidCVE_2016_2143();
 
   SetCanPoisonMemory(flags()->poison_heap);
   SetMallocContextSize(common_flags()->malloc_context_size);
 
+  InitializePlatformExceptionHandlers();
+
   InitializeHighMemEnd();
 
   // Make sure we are not statically linked.
   AsanDoesNotSupportStaticLinkage();
 
   // Install tool-specific callbacks in sanitizer_common.
   AddDieCallback(AsanDie);
   SetCheckFailedCallback(AsanCheckFailed);

lib/asan/asan_win.cc

 
 #include <stdlib.h>
 
 #include "asan_interceptors.h"
 #include "asan_internal.h"
 #include "asan_report.h"
 #include "asan_stack.h"
 #include "asan_thread.h"
+#include "asan_mapping.h"
 #include "sanitizer_common/sanitizer_libc.h"
 #include "sanitizer_common/sanitizer_mutex.h"
 
 using namespace __asan;  // NOLINT
 
 extern "C" {
 SANITIZER_INTERFACE_ATTRIBUTE
 int __asan_should_detect_stack_use_after_return() {

 void ReadContextStack(void *context, uptr *stack, uptr *ssize) {
   UNIMPLEMENTED();
 }
 
 void AsanOnDeadlySignal(int, void *siginfo, void *context) {
   UNIMPLEMENTED();
 }
 
+#if SANITIZER_WINDOWS64
+// Exception handler for dealing with shadow memory.
+static LONG CALLBACK
+ShadowExceptionHandler(PEXCEPTION_POINTERS exception_pointers) {
+  static uptr page_size = GetPageSizeCached();
+  static uptr alloc_granularity = GetMmapGranularity();
+  // Only handle access violations.
+  if (exception_pointers->ExceptionRecord->ExceptionCode !=
+      EXCEPTION_ACCESS_VIOLATION) {
+    return EXCEPTION_CONTINUE_SEARCH;
+  }
+
+  // Only handle access violations that land within the shadow memory.
+  uptr addr = (uptr)(exception_pointers->ExceptionRecord->ExceptionInformation[1]);
+
+  // Check valid shadow range.
+  if (!AddrIsInShadow(addr)) return EXCEPTION_CONTINUE_SEARCH;
+
+  // This is an access violation while trying to read from the shadow. Commit
+  // the relevant page and let execution continue.
+
+  // Determine the address of the page that is being accessed.
+  uptr page = RoundDownTo(addr, page_size);
+
+  // Query the existing page.
+  MEMORY_BASIC_INFORMATION mem_info = {};
+  if (::VirtualQuery((LPVOID)page, &mem_info, sizeof(mem_info)) == 0)
+    return EXCEPTION_CONTINUE_SEARCH;
+
+  // If the memory isn't part of any reservation, then reserve the chunk of
+  // pages.
+  if (mem_info.AllocationBase == 0) {
+    uptr chunk = RoundDownTo(addr, alloc_granularity);
+    uptr result = (uptr)
+        ::VirtualAlloc((LPVOID)chunk, alloc_granularity, MEM_RESERVE, PAGE_READONLY);
+    if (result != chunk) return EXCEPTION_CONTINUE_SEARCH;
+  }
+
+  // Commit the page.
+  uptr result = (uptr)::VirtualAlloc((LPVOID)page, page_size, MEM_COMMIT, PAGE_READWRITE);
+  if (result != page) return EXCEPTION_CONTINUE_SEARCH;
+
+  // The page mapping succeeded, so continue execution as usual.
+  return EXCEPTION_CONTINUE_EXECUTION;
+}
+
+#endif
+
+void InitializePlatformExceptionHandlers() {
+#if SANITIZER_WINDOWS64
+  // On Win64, we map memory on demand with access violation handler.
+  // Install our exception handler.
+  if (!AddVectoredExceptionHandler(TRUE, &ShadowExceptionHandler)) {
+    // It is critical this handler must work.
+    __debugbreak();
+  }
+#endif
+}
+
 static LPTOP_LEVEL_EXCEPTION_FILTER default_seh_handler;
 
 static long WINAPI SEHHandler(EXCEPTION_POINTERS *info) {
   EXCEPTION_RECORD *exception_record = info->ExceptionRecord;
   CONTEXT *context = info->ContextRecord;
 
   if (exception_record->ExceptionCode == EXCEPTION_ACCESS_VIOLATION ||
       exception_record->ExceptionCode == EXCEPTION_IN_PAGE_ERROR) {
     const char *description =
         (exception_record->ExceptionCode == EXCEPTION_ACCESS_VIOLATION)
             ? "access-violation"