[NTOS] Re-enable the APC debug check in the system call exit code that somehow got removed in 46247.

[NTOS] Use an inline for emitting the iret instruction in C code for portability.
[NTOS] Simplify the MSC assembly in KiSwitchToBootStack.

svn path=/trunk/; revision=47487

reactos/ntoskrnl/include/internal/i386/ke.h

@@ -774,8 +774,7 @@ KiSwitchToBootStack(IN ULONG_PTR InitialStack)
     VOID NTAPI KiSystemStartupBootStack(VOID);
     __asm
     {
-        mov ecx, InitialStack
-        mov esp, ecx
+        mov esp, InitialStack
         sub esp, (NPX_FRAME_LENGTH + KTRAP_FRAME_ALIGN + KTRAP_FRAME_LENGTH)
         push (CR0_EM | CR0_TS | CR0_MP)
         jmp KiSystemStartupBootStack
@@ -785,6 +784,30 @@ KiSwitchToBootStack(IN ULONG_PTR InitialStack)
 #endif
 }
 
+//
+// Emits the iret instruction for C code
+//
+DECLSPEC_NORETURN
+VOID
+FORCEINLINE
+KiIret(VOID)
+{
+#if defined(__GNUC__)
+    __asm__ __volatile__
+    (
+        "iret\n"
+    );
+#elif defined(_MSC_VER)
+    __asm
+    {
+        iret
+    }
+#else
+#error Unsupported compiler
+#endif
+    UNREACHABLE;
+}
+
 //
 // Normally this is done by the HAL, but on x86 as an optimization, the kernel
 // initiates the end by calling back into the HAL and exiting the trap here.

reactos/ntoskrnl/include/internal/trap_x.h

@@ -8,7 +8,7 @@
 
 #pragma once
 
-//#define TRAP_DEBUG 1
+#define TRAP_DEBUG 0
 
 //
 // Unreachable code hint for GCC 4.5.x, older GCC versions, and MSVC
@@ -81,7 +81,7 @@ KiDumpTrapFrame(IN PKTRAP_FRAME TrapFrame)
     DbgPrint("V86Gs: %x\n", TrapFrame->V86Gs);
 }
 
-#ifdef TRAP_DEBUG
+#if TRAP_DEBUG
 VOID
 FORCEINLINE
 KiFillTrapFrameDebug(IN PKTRAP_FRAME TrapFrame)
@@ -168,7 +168,7 @@ KiExitSystemCallDebugChecks(IN ULONG SystemCall,
                          0,
                          0);
         }
-#if 0
+
         /* Make sure we're not attached and that APCs are not disabled */
         if ((KeGetCurrentThread()->ApcStateIndex != CurrentApcEnvironment) ||
             (KeGetCurrentThread()->CombinedApcDisable != 0))
@@ -180,7 +180,6 @@ KiExitSystemCallDebugChecks(IN ULONG SystemCall,
                          KeGetCurrentThread()->CombinedApcDisable,
                          0);
         }
-#endif
     }
 }
 #else
@@ -200,9 +199,11 @@ DECLSPEC_NORETURN VOID FASTCALL KiTrapReturn(IN PKTRAP_FRAME TrapFrame);
 DECLSPEC_NORETURN VOID FASTCALL KiTrapReturnNoSegments(IN PKTRAP_FRAME TrapFrame);
 
 typedef
+DECLSPEC_NORETURN
 VOID
-(FASTCALL
-*PFAST_SYSTEM_CALL_EXIT)(IN PKTRAP_FRAME TrapFrame);
+(FASTCALL *PFAST_SYSTEM_CALL_EXIT)(
+    IN PKTRAP_FRAME TrapFrame
+);
 
 extern PFAST_SYSTEM_CALL_EXIT KiFastCallExitHandler;
 
@@ -222,7 +223,7 @@ KiExitV86Trap(IN PKTRAP_FRAME TrapFrame)
     while (TRUE)
     {
         /* Return if this isn't V86 mode anymore */
-        if (!(TrapFrame->EFlags & EFLAGS_V86_MASK)) KiEoiHelper(TrapFrame);;
+        if (!(TrapFrame->EFlags & EFLAGS_V86_MASK)) KiEoiHelper(TrapFrame);
 
         /* Turn off the alerted state for kernel mode */
         Thread->Alerted[KernelMode] = FALSE;

reactos/ntoskrnl/ke/i386/traphdlr.c

@@ -547,7 +547,7 @@ KiTrap02(VOID)
         //
         // Handled, return from interrupt
         //
-        __asm__ __volatile__ ("iret\n");
+        KiIret();
     }
     
     //