From c84fd405bff4f94b76e24aefea49bf7b2dc65781 Mon Sep 17 00:00:00 2001
From: ReactOS Portable Systems Group <ros-arm-bringup@svn.reactos.org>
Date: Wed, 11 Jun 2008 19:13:25 +0000
Subject: [PATCH] - We now implement a skeleton framework for context switching
 - The only things we do are swap the stack and then display the old/new
 thread/stack. - More work to be done to actually save the non-volatiles,
 prepare the thread state, and restore the volatiles for the new thread. -
 Then we will return to the saved return address, and we should be in Phase 1
 with working thread switching/scheduling.

svn path=/trunk/; revision=33935
---
 reactos/ntoskrnl/include/internal/arm/ksarm.h |  5 ++
 reactos/ntoskrnl/ke/arm/ctxswtch.s            | 50 +++++++++++++++++++
 reactos/ntoskrnl/ke/arm/stubs.c               |  2 +
 reactos/ntoskrnl/ke/arm/stubs_asm.s           |  3 --
 reactos/ntoskrnl/ke/arm/trapc.c               | 18 ++++++-
 reactos/ntoskrnl/ntoskrnl-generic.rbuild      |  1 +
 6 files changed, 74 insertions(+), 5 deletions(-)
 create mode 100644 reactos/ntoskrnl/ke/arm/ctxswtch.s

diff --git a/reactos/ntoskrnl/include/internal/arm/ksarm.h b/reactos/ntoskrnl/include/internal/arm/ksarm.h
index 98b95061618..17c06dc67b2 100644
--- a/reactos/ntoskrnl/include/internal/arm/ksarm.h
+++ b/reactos/ntoskrnl/include/internal/arm/ksarm.h
@@ -55,6 +55,11 @@
  */
 .equ PcCurrentIrql,        0x14C
 
+/*
+ * KTHREAD Offsets
+ */
+.equ ThKernelStack,        0x20
+
 #else
 
 /*
diff --git a/reactos/ntoskrnl/ke/arm/ctxswtch.s b/reactos/ntoskrnl/ke/arm/ctxswtch.s
new file mode 100644
index 00000000000..6b28048ed91
--- /dev/null
+++ b/reactos/ntoskrnl/ke/arm/ctxswtch.s
@@ -0,0 +1,50 @@
+/*
+ * PROJECT:         ReactOS Kernel
+ * LICENSE:         GPL - See COPYING in the top level directory
+ * FILE:            ntoskrnl/ke/arm/ctxswtch.s
+ * PURPOSE:         Context Switch and Idle Thread on ARM
+ * PROGRAMMERS:     ReactOS Portable Systems Group
+ */
+
+    .title "ARM Context Switching"
+    .include "ntoskrnl/include/internal/arm/kxarm.h"
+    .include "ntoskrnl/include/internal/arm/ksarm.h"
+
+    TEXTAREA
+    NESTED_ENTRY KiSwapContext
+    PROLOG_END KiSwapContext
+    //
+    // a1 = Old Thread
+    // a2 = New Thread
+    //
+    
+    //
+    // Save volatile registers for the OLD thread
+    //
+    
+    //
+    // Switch stacks
+    //
+    str sp, [a1, #ThKernelStack]
+    ldr sp, [a2, #ThKernelStack]
+    
+    //
+    // Call the C context switch code
+    //
+    bl KiSwapContextInternal
+    
+    //
+    // Restore volatile registers for the NEW thread
+    //
+    
+    //
+    // Jump to saved restore address
+    //
+    
+    //
+    // FIXME: TODO
+    //
+    b .
+    
+    ENTRY_END KiSwapContext
+
diff --git a/reactos/ntoskrnl/ke/arm/stubs.c b/reactos/ntoskrnl/ke/arm/stubs.c
index 6eafcbecfcd..b18c76407ba 100644
--- a/reactos/ntoskrnl/ke/arm/stubs.c
+++ b/reactos/ntoskrnl/ke/arm/stubs.c
@@ -2,6 +2,8 @@
 #define NDEBUG
 #include "debug.h"
 
+CCHAR KeNumberProcessors;
+ULONG KeDcacheFlushCount;
 ULONG KeActiveProcessors;
 ULONG KeProcessorArchitecture;
 ULONG KeProcessorLevel;
diff --git a/reactos/ntoskrnl/ke/arm/stubs_asm.s b/reactos/ntoskrnl/ke/arm/stubs_asm.s
index ea6442f09b7..8e2b242e01a 100644
--- a/reactos/ntoskrnl/ke/arm/stubs_asm.s
+++ b/reactos/ntoskrnl/ke/arm/stubs_asm.s
@@ -12,17 +12,14 @@ GENERATE_ARM_STUB _local_unwind2
 //
 // Exported Ke Arch-Specific APIs
 //
-GENERATE_ARM_STUB KiSwapContext
 GENERATE_ARM_STUB DbgBreakPointWithStatus 
 GENERATE_ARM_STUB KeConnectInterrupt 
-GENERATE_ARM_STUB KeDcacheFlushCount 
 GENERATE_ARM_STUB KeDisconnectInterrupt 
 GENERATE_ARM_STUB KeFlushEntireTb 
 GENERATE_ARM_STUB KeGetRecommendedSharedDataAlignment 
 GENERATE_ARM_STUB KeIcacheFlushCount 
 GENERATE_ARM_STUB KeInitializeInterrupt 
 GENERATE_ARM_STUB KeInvalidateAllCaches
-GENERATE_ARM_STUB KeNumberProcessors 
 GENERATE_ARM_STUB KeQueryActiveProcessors 
 GENERATE_ARM_STUB KeRaiseUserException 
 GENERATE_ARM_STUB KeSaveStateForHibernate 
diff --git a/reactos/ntoskrnl/ke/arm/trapc.c b/reactos/ntoskrnl/ke/arm/trapc.c
index 13da1a188ba..05e5f7dafd4 100644
--- a/reactos/ntoskrnl/ke/arm/trapc.c
+++ b/reactos/ntoskrnl/ke/arm/trapc.c
@@ -24,7 +24,6 @@ KiSystemCall(
     IN PULONG Arguments,
     IN ULONG ArgumentCount
 );
- 
 
 /* FUNCTIONS ******************************************************************/
 
@@ -34,6 +33,18 @@ HalGetInterruptSource(VOID);
 VOID FASTCALL
 HalClearSoftwareInterrupt(IN KIRQL Request);
 
+VOID
+KiSwapContextInternal(IN PKTHREAD OldThread,
+                      IN PKTHREAD NewThread)
+{
+    //
+    // FIXME: TODO
+    //
+    DPRINT1("Switching from: %p to %p\n", OldThread, NewThread);
+    DPRINT1("Stacks: %p %p\n", OldThread->KernelStack, NewThread->KernelStack);
+    while (TRUE);
+}
+
 VOID
 KiDispatchInterrupt(VOID)
 {
@@ -107,9 +118,12 @@ KiDispatchInterrupt(VOID)
         
         //
         // Swap to the new thread
+        // On ARM we call KiSwapContext instead of KiSwapContextInternal,
+        // because we're calling this from C code and not assembly.
+        // This is similar to how it gets called for unwaiting, on x86
         //
         DPRINT1("Swapping context!\n");
-        //KiSwapContextInternal();
+        KiSwapContext(OldThread, NewThread);
         while (TRUE);
     }
 }
diff --git a/reactos/ntoskrnl/ntoskrnl-generic.rbuild b/reactos/ntoskrnl/ntoskrnl-generic.rbuild
index 51c35f9c41a..b5e1fd572ce 100644
--- a/reactos/ntoskrnl/ntoskrnl-generic.rbuild
+++ b/reactos/ntoskrnl/ntoskrnl-generic.rbuild
@@ -63,6 +63,7 @@
 				<file first="true">boot.s</file>
 				<file>arm_kprintf.c</file>
 				<file>cpu.c</file>
+				<file>ctxswtch.s</file>
 				<file>exp.c</file>
 				<file>kiinit.c</file>
 				<file>stubs_asm.s</file>