ntdll: Handle icebp on x86-64.

dlls/ntdll/signal_x86_64.c

@@ -2917,6 +2917,12 @@ static void trap_handler( int signal, siginfo_t *siginfo, void *sigcontext )
         rec->ExceptionCode = EXCEPTION_SINGLE_STEP;
         break;
     case TRAP_BRKPT:   /* Breakpoint exception */
+        /* Check if this is actuallly icebp instruction */
+        if (((unsigned char *)rec->ExceptionAddress)[-1] == 0xF1)
+        {
+            rec->ExceptionCode = EXCEPTION_SINGLE_STEP;
+            break;
+        }
         rec->ExceptionAddress = (char *)rec->ExceptionAddress - 1;  /* back up over the int3 instruction */
         /* fall through */
     default:

dlls/ntdll/tests/exception.c

@@ -2292,10 +2292,8 @@ static const struct exception
 /* 35 */
     { { 0xa3, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc3 },  /* movl %eax,0xffffffffffffffff; ret */
       0, 9, STATUS_ACCESS_VIOLATION, 2, { 1, 0xffffffffffffffff } },
-#if 0
     { { 0xf1, 0x90, 0xc3 },  /* icebp; nop; ret */
       1, 1, STATUS_SINGLE_STEP, 0 },
-#endif
     { { 0xcd, 0x2c, 0xc3 },
       0, 2, STATUS_ASSERTION_FAILURE, 0 },
 };