From 5e9aa4043f82eba950cb0afd353d183b3c688fe4 Mon Sep 17 00:00:00 2001
From: John Hodge <tpg@portege.thepowersgang.com>
Date: Sun, 27 Sep 2009 13:37:56 +0800
Subject: [PATCH] Added tracing of task switches

---
 Kernel/arch/x86/proc.c | 11 +++++++++++
 Kernel/syscalls.c      |  4 ++--
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/Kernel/arch/x86/proc.c b/Kernel/arch/x86/proc.c
index d468d11a..f04793a2 100644
--- a/Kernel/arch/x86/proc.c
+++ b/Kernel/arch/x86/proc.c
@@ -10,6 +10,9 @@
 # include <mp.h>
 #endif
 
+// === FLAGS ===
+#define DEBUG_TRACE_SWITCH	1
+
 // === CONSTANTS ===
 #define	SWITCH_MAGIC	0xFFFACE55	// There is no code in this area
 #define TIMER_DIVISOR	11931	//~100Hz
@@ -497,6 +500,14 @@ void Proc_Scheduler(int CPU)
 		return;
 	}
 	
+	#if DEBUG_TRACE_SWITCH
+	Log("Switching to task %i, CR3 = 0x%x, EIP = %p",
+		thread->TID,
+		thread->MemState.CR3,
+		thread->SavedState.EIP
+		);
+	#endif
+	
 	// Set current thread
 	gCurrentThread = thread;
 	
diff --git a/Kernel/syscalls.c b/Kernel/syscalls.c
index f655707c..74eaaeaa 100644
--- a/Kernel/syscalls.c
+++ b/Kernel/syscalls.c
@@ -57,8 +57,8 @@ void SyscallHandler(tSyscallRegs *Regs)
 	case SYS_CLONE:
 		// Call clone system call
 		ret = Proc_Clone(&err, Regs->Arg1);
-		// Change user stack if requested
-		if(ret == 0 && !(Regs->Arg1 & CLONE_VM))
+		// Change user stack if a new stack address is passed
+		if(ret == 0 && Regs->Arg2)
 			Regs->StackPointer = Regs->Arg2;
 		break;
 	
-- 
2.20.1