diff --git a/reactos/ntoskrnl/include/internal/arm/ksarm.h b/reactos/ntoskrnl/include/internal/arm/ksarm.h
index 0ded6e44f5a..91adf08672e 100644
--- a/reactos/ntoskrnl/include/internal/arm/ksarm.h
+++ b/reactos/ntoskrnl/include/internal/arm/ksarm.h
@@ -62,7 +62,7 @@
 .equ TrSvcLr,              0x44
 .equ TrPc,                 0x48
 .equ TrSpsr,               0x4C
-.equ TrapFrameLength,      (22 * 0x04)
+.equ TrapFrameLength,      (23 * 0x04)
 
 /*
  * Exception Frame offsets
diff --git a/reactos/ntoskrnl/ke/arm/trap.s b/reactos/ntoskrnl/ke/arm/trap.s
index fde9d354f5c..26a4d523976 100644
--- a/reactos/ntoskrnl/ke/arm/trap.s
+++ b/reactos/ntoskrnl/ke/arm/trap.s
@@ -31,7 +31,6 @@
     TEXTAREA
     NESTED_ENTRY KiUndefinedInstructionException
     PROLOG_END KiUndefinedInstructionException
-    
     //
     // Handle trap entry
     //
@@ -40,21 +39,14 @@
     //
     // Call the C handler
     //
-    adr lr, 1f
+    ldr lr, =KiExceptionExit
     mov r0, sp
     ldr pc, =KiUndefinedExceptionHandler
-    
-1:
-    //
-    // Handle trap exit
-    // 
-    TRAP_EPILOG 0 // NotFromSystemCall
-    
     ENTRY_END KiUndefinedInstructionException
     
+    
     NESTED_ENTRY KiSoftwareInterruptException
     PROLOG_END KiSoftwareInterruptException
-
     //
     // Handle trap entry
     //
@@ -63,21 +55,14 @@
     //
     // Call the C handler
     //
-    adr lr, 1f
+    ldr lr, =KiServiceExit
     mov r0, sp
     ldr pc, =KiSoftwareInterruptHandler
-    
-1:
-    //
-    // Handle trap exit
-    // 
-    TRAP_EPILOG 1 // FromSystemCall
-    
     ENTRY_END KiSoftwareInterruptException
 
+
     NESTED_ENTRY KiPrefetchAbortException
     PROLOG_END KiPrefetchAbortException
-    
     //
     // Handle trap entry
     //
@@ -86,21 +71,14 @@
     //
     // Call the C handler
     //
-    adr lr, 1f
+    ldr lr, =KiExceptionExit
     mov r0, sp
     ldr pc, =KiPrefetchAbortHandler
-    
-1:
-    //
-    // Handle trap exit
-    // 
-    TRAP_EPILOG 0 // NotFromSystemCall
-    
     ENTRY_END KiPrefetchAbortException
 
+
     NESTED_ENTRY KiDataAbortException
     PROLOG_END KiDataAbortException
-    
     //
     // Handle trap entry
     //
@@ -109,21 +87,14 @@
     //
     // Call the C handler
     //
-    adr lr, 1f
+    ldr lr, =KiExceptionExit
     mov r0, sp
     ldr pc, =KiDataAbortHandler
-
-1:
-    //
-    // Handle trap exit
-    // 
-    TRAP_EPILOG 0 // NotFromSystemCall
-    
     ENTRY_END KiDataAbortException
 
+
     NESTED_ENTRY KiInterruptException
     PROLOG_END KiInterruptException
-        
     //
     // Handle trap entry
     //
@@ -132,25 +103,35 @@
     //
     // Call the C handler
     //
-    adr lr, 1f
+    ldr lr, =KiExceptionExit
     mov r0, sp
     mov r1, #0
     ldr pc, =KiInterruptHandler
-    
-1:
-    //
-    // Handle trap exit
-    // 
-    TRAP_EPILOG 0 // NotFromSystemCall
-    
     ENTRY_END KiInterruptException
 
+
     NESTED_ENTRY KiFastInterruptException
     PROLOG_END KiFastInterruptException
-    
     //
     // FIXME-PERF: Implement FIQ exception
     //
     b .
-    
     ENTRY_END KiFastInterruptException
+    
+    
+    NESTED_ENTRY KiExceptionExit
+    PROLOG_END KiExceptionExit
+    //
+    // Handle trap exit
+    // 
+    TRAP_EPILOG 0 // NotFromSystemCall
+    ENTRY_END KiExceptionExit
+
+
+    NESTED_ENTRY KiServiceExit
+    PROLOG_END KiServiceExit
+    //
+    // Handle trap exit
+    // 
+    TRAP_EPILOG 1 // FromSystemCall
+    ENTRY_END KiServiceExit
diff --git a/reactos/ntoskrnl/ke/arm/trapc.c b/reactos/ntoskrnl/ke/arm/trapc.c
index 28581e9c005..71a56216529 100644
--- a/reactos/ntoskrnl/ke/arm/trapc.c
+++ b/reactos/ntoskrnl/ke/arm/trapc.c
@@ -457,7 +457,6 @@ KiPrefetchAbortHandler(IN PKTRAP_FRAME TrapFrame)
     //
     // Unhandled
     //
-    while (TRUE);
     DPRINT1("[PREFETCH ABORT] (%x) @ %p/%p/%p\n",
             KeArmInstructionFaultStatusRegisterGet(), Address, TrapFrame->SvcLr, TrapFrame->Pc);
     UNIMPLEMENTED;
@@ -516,6 +515,7 @@ KiSoftwareInterruptHandler(IN PKTRAP_FRAME TrapFrame)
     // Save old previous mode
     //
     TrapFrame->PreviousMode = PreviousMode;
+    TrapFrame->PreviousTrapFrame = (ULONG_PTR)Thread->TrapFrame;
     
     //
     // Save previous mode and trap frame
diff --git a/reactos/ntoskrnl/ke/arm/usercall.c b/reactos/ntoskrnl/ke/arm/usercall.c
index 7ffc6ad0668..1f11468d834 100644
--- a/reactos/ntoskrnl/ke/arm/usercall.c
+++ b/reactos/ntoskrnl/ke/arm/usercall.c
@@ -9,6 +9,7 @@
 /* INCLUDES *******************************************************************/
 
 #include <ntoskrnl.h>
+#include <internal/arm/ksarm.h>
 #define NDEBUG
 #include <debug.h>
 
@@ -90,6 +91,7 @@ KiSystemService(IN PKTHREAD Thread,
     PVOID SystemCall;
     PVOID* Argument;
     PVOID Arguments[0x11]; // Maximum 17 arguments
+    KIRQL OldIrql;
     ASSERT(TrapFrame->DbgArgMark == 0xBADB0D00);
     
     //
@@ -209,4 +211,53 @@ KiSystemService(IN PKTHREAD Thread,
     //
     TrapFrame->R0 = KiSyscallHandlers[ArgumentCount]((PVOID)SystemCall,
                                                      (PVOID)Arguments);
+                                                     
+    //
+    // Check if this was a user call
+    //
+    if (KiGetPreviousMode(TrapFrame) == UserMode)
+    {
+        //
+        // Make sure we didn't return at elevated IRQL
+        //
+        OldIrql = KeGetCurrentIrql();
+        if (OldIrql != PASSIVE_LEVEL)
+        {
+            //
+            // Forcibly put us in a sane state
+            //
+            KeGetPcr()->CurrentIrql = 0;
+            _disable();
+            
+            //
+            // Fail
+            //
+            KeBugCheckEx(IRQL_GT_ZERO_AT_SYSTEM_SERVICE,
+                         (ULONG_PTR)SystemCall,
+                         OldIrql,
+                         0,
+                         0);
+        }
+        
+        //
+        // Make sure we're not attached and that APCs are not disabled
+        //
+        if ((KeGetCurrentThread()->ApcStateIndex != CurrentApcEnvironment) ||
+            (KeGetCurrentThread()->CombinedApcDisable != 0))
+        {
+            //
+            // Fail
+            //
+            KeBugCheckEx(APC_INDEX_MISMATCH,
+                         (ULONG_PTR)SystemCall,
+                         KeGetCurrentThread()->ApcStateIndex,
+                         KeGetCurrentThread()->CombinedApcDisable,
+                         0);
+        }
+    }
+    
+    //
+    // Restore the old trap frame
+    //
+    Thread->TrapFrame = (PKTRAP_FRAME)TrapFrame->PreviousTrapFrame;
 }