Merge M45: Add support for int 2e fallback system call stub in Win10.

BUG=522201
TEST=sbox_integration_tests on Win 10 build 10525

Review URL: https://codereview.chromium.org/1291043003

Cr-Commit-Position: refs/heads/master@{#344588}
(cherry picked from commit 1453ac3a6d190b21e04d578d5cf71ce19877db47)

Review URL: https://codereview.chromium.org/1308563005.

Cr-Commit-Position: refs/branch-heads/2454@{#394}
Cr-Branched-From: 12bfc3360892ec53cd00fc239a47e5298beb063b-refs/heads/master@{#338390}
diff --git a/sandbox/win/src/service_resolver_64.cc b/sandbox/win/src/service_resolver_64.cc
index 8c0ae96..c0e684c 100644
--- a/sandbox/win/src/service_resolver_64.cc
+++ b/sandbox/win/src/service_resolver_64.cc
@@ -17,6 +17,10 @@
 const ULONG64 kMov1 = 0x54894808244C8948;
 const ULONG64 kMov2 = 0x4C182444894C1024;
 const ULONG kMov3 = 0x20244C89;
+const USHORT kTestByte = 0x04F6;
+const BYTE kPtr = 0x25;
+const BYTE kRet = 0xC3;
+const USHORT kJne = 0x0375;
 
 // Service code for 64 bit systems.
 struct ServiceEntry {
@@ -60,11 +64,37 @@
   BYTE nop;                   // = 90
 };
 
+// Service code for 64 bit systems with int 2e fallback.
+struct ServiceEntryWithInt2E {
+  // This struct contains roughly the following code:
+  // 00 4c8bd1           mov     r10,rcx
+  // 03 b855000000       mov     eax,52h
+  // 08 f604250803fe7f01 test byte ptr SharedUserData!308, 1
+  // 10 7503             jne [over syscall]
+  // 12 0f05             syscall
+  // 14 c3               ret
+  // 15 cd2e             int 2e
+  // 17 c3               ret
+
+  ULONG mov_r10_rcx_mov_eax;  // = 4C 8B D1 B8
+  ULONG service_id;
+  USHORT test_byte;           // = F6 04
+  BYTE ptr;                   // = 25
+  ULONG user_shared_data_ptr;
+  BYTE one;                   // = 01
+  USHORT jne_over_syscall;    // = 75 03
+  USHORT syscall;             // = 0F 05
+  BYTE ret;                   // = C3
+  USHORT int2e;               // = CD 2E
+  BYTE ret2;                  // = C3
+};
+
 // We don't have an internal thunk for x64.
 struct ServiceFullThunk {
   union {
     ServiceEntry original;
     ServiceEntryW8 original_w8;
+    ServiceEntryWithInt2E original_int2e_fallback;
   };
 };
 
@@ -78,6 +108,25 @@
           kSyscall == service->syscall && kRetNp == service->ret);
 }
 
+bool IsServiceW8(const void* source) {
+  const ServiceEntryW8* service =
+      reinterpret_cast<const ServiceEntryW8*>(source);
+
+  return (kMmovR10EcxMovEax == service->mov_r10_rcx_mov_eax &&
+          kMov1 == service->mov_1 && kMov2 == service->mov_2 &&
+          kMov3 == service->mov_3);
+}
+
+bool IsServiceWithInt2E(const void* source) {
+  const ServiceEntryWithInt2E* service =
+      reinterpret_cast<const ServiceEntryWithInt2E*>(source);
+
+  return (kMmovR10EcxMovEax == service->mov_r10_rcx_mov_eax &&
+          kTestByte == service->test_byte && kPtr == service->ptr &&
+          kJne == service->jne_over_syscall && kSyscall == service->syscall &&
+          kRet == service->ret && kRet == service->ret2);
+}
+
 };  // namespace
 
 namespace sandbox {
@@ -150,15 +199,9 @@
   if (sizeof(function_code) != read)
     return false;
 
-  if (!IsService(&function_code)) {
-    // See if it's the Win8 signature.
-    ServiceEntryW8* w8_service = &function_code.original_w8;
-    if (!IsService(&w8_service->mov_r10_rcx_mov_eax) ||
-        w8_service->mov_1 != kMov1 || w8_service->mov_2 != kMov2 ||
-        w8_service->mov_3 != kMov3) {
-      return false;
-    }
-  }
+  if (!IsService(&function_code) && !IsServiceW8(&function_code) &&
+      !IsServiceWithInt2E(&function_code))
+    return false;
 
   // Save the verified code.
   memcpy(local_thunk, &function_code, sizeof(function_code));