diff -urNp linux-2.6.17.previous/arch/i386/kernel/entry-xen.S linux-2.6.17.noarch/arch/i386/kernel/entry-xen.S
--- linux-2.6.17.previous/arch/i386/kernel/entry-xen.S	2006-07-19 16:27:09.000000000 +0200
+++ linux-2.6.17.noarch/arch/i386/kernel/entry-xen.S	2006-07-19 17:48:25.000000000 +0200
@@ -340,7 +340,7 @@ sysenter_past_esp:
 	GET_THREAD_INFO(%ebp)
 
 	/* Note, _TIF_SECCOMP is bit number 8, and so it needs testw and not testb */
-	testw $(_TIF_SYSCALL_EMU|_TIF_SYSCALL_TRACE|_TIF_SECCOMP|_TIF_SYSCALL_AUDIT),TI_flags(%ebp)
+	testw $(_TIF_SYSCALL_TRACE|_TIF_SECCOMP|_TIF_SYSCALL_AUDIT),TI_flags(%ebp)
 	jnz syscall_trace_entry
 	cmpl $(nr_syscalls), %eax
 	jae syscall_badsys
@@ -389,7 +389,7 @@ ENTRY(system_call)
 no_singlestep:
 					# system call tracing in operation / emulation
 	/* Note, _TIF_SECCOMP is bit number 8, and so it needs testw and not testb */
-	testw $(_TIF_SYSCALL_EMU|_TIF_SYSCALL_TRACE|_TIF_SECCOMP|_TIF_SYSCALL_AUDIT),TI_flags(%ebp)
+	testw $(_TIF_SYSCALL_TRACE|_TIF_SECCOMP|_TIF_SYSCALL_AUDIT),TI_flags(%ebp)
 	jnz syscall_trace_entry
 	cmpl $(nr_syscalls), %eax
 	jae syscall_badsys
@@ -539,9 +539,6 @@ syscall_trace_entry:
 	movl %esp, %eax
 	xorl %edx,%edx
 	call do_syscall_trace
-	cmpl $0, %eax
-	jne resume_userspace		# ret != 0 -> running under PTRACE_SYSEMU,
-					# so must skip actual syscall
 	movl ORIG_EAX(%esp), %eax
 	cmpl $(nr_syscalls), %eax
 	jnae syscall_call
diff -urNp linux-2.6.17.previous/arch/i386/kernel/process-xen.c linux-2.6.17.noarch/arch/i386/kernel/process-xen.c
--- linux-2.6.17.previous/arch/i386/kernel/process-xen.c	2006-07-19 16:27:11.000000000 +0200
+++ linux-2.6.17.noarch/arch/i386/kernel/process-xen.c	2006-07-19 17:46:21.000000000 +0200
@@ -657,9 +657,6 @@ asmlinkage int sys_execve(struct pt_regs
 			(char __user * __user *) regs.edx,
 			&regs);
 	if (error == 0) {
-		task_lock(current);
-		current->ptrace &= ~PT_DTRACE;
-		task_unlock(current);
 		/* Make sure we don't return using sysenter.. */
 		set_thread_flag(TIF_IRET);
 	}
diff -urNp linux-2.6.17.previous/arch/x86_64/ia32/ia32entry-xen.S linux-2.6.17.noarch/arch/x86_64/ia32/ia32entry-xen.S
--- linux-2.6.17.previous/arch/x86_64/ia32/ia32entry-xen.S	2006-07-19 16:27:10.000000000 +0200
+++ linux-2.6.17.noarch/arch/x86_64/ia32/ia32entry-xen.S	2006-07-19 17:53:16.000000000 +0200
@@ -444,7 +444,7 @@ ia32_sys_call_table:
 	.quad sys_setuid16
 	.quad sys_getuid16
 	.quad compat_sys_stime	/* stime */		/* 25 */
-	.quad sys32_ptrace	/* ptrace */
+	.quad compat_sys_ptrace	/* ptrace */
 	.quad sys_alarm
 	.quad sys_fstat	/* (old)fstat */
 	.quad sys_pause
diff -urNp linux-2.6.17.previous/arch/x86_64/kernel/process-xen.c linux-2.6.17.noarch/arch/x86_64/kernel/process-xen.c
--- linux-2.6.17.previous/arch/x86_64/kernel/process-xen.c	2006-07-19 16:27:11.000000000 +0200
+++ linux-2.6.17.noarch/arch/x86_64/kernel/process-xen.c	2006-07-19 17:52:39.000000000 +0200
@@ -580,11 +580,6 @@ long sys_execve(char __user *name, char 
 	if (IS_ERR(filename)) 
 		return error;
 	error = do_execve(filename, argv, envp, &regs); 
-	if (error == 0) {
-		task_lock(current);
-		current->ptrace &= ~PT_DTRACE;
-		task_unlock(current);
-	}
 	putname(filename);
 	return error;
 }
diff -urNp linux-2.6.17.previous/arch/x86_64/kernel/traps-xen.c linux-2.6.17.noarch/arch/x86_64/kernel/traps-xen.c
--- linux-2.6.17.previous/arch/x86_64/kernel/traps-xen.c	2006-07-19 16:27:10.000000000 +0200
+++ linux-2.6.17.noarch/arch/x86_64/kernel/traps-xen.c	2006-07-19 17:51:56.000000000 +0200
@@ -863,14 +863,6 @@ asmlinkage void __kprobes do_debug(struc
 		 */
                 if (!user_mode(regs))
                        goto clear_TF_reenable;
-		/*
-		 * Was the TF flag set by a debugger? If so, clear it now,
-		 * so that register information is correct.
-		 */
-		if (tsk->ptrace & PT_DTRACE) {
-			regs->eflags &= ~TF_MASK;
-			tsk->ptrace &= ~PT_DTRACE;
-		}
 	}
 
 	/* Ok, finally something we can handle */
diff -urNp linux-2.6.17.previous/arch/x86_64/mm/fault-xen.c linux-2.6.17.noarch/arch/x86_64/mm/fault-xen.c
--- linux-2.6.17.previous/arch/x86_64/mm/fault-xen.c	2006-07-19 16:27:11.000000000 +0200
+++ linux-2.6.17.noarch/arch/x86_64/mm/fault-xen.c	2006-07-19 18:01:52.000000000 +0200
@@ -11,7 +11,7 @@
 #include <linux/errno.h>
 #include <linux/string.h>
 #include <linux/types.h>
-#include <linux/ptrace.h>
+#include <linux/tracehook.h>
 #include <linux/mman.h>
 #include <linux/mm.h>
 #include <linux/smp.h>
@@ -250,7 +250,7 @@ int unhandled_signal(struct task_struct 
 {
 	if (tsk->pid == 1)
 		return 1;
-	if (tsk->ptrace & PT_PTRACED)
+	if (tracehook_consider_fatal_signal(tsk, sig))
 		return 0;
 	return (tsk->sighand->action[sig-1].sa.sa_handler == SIG_IGN) ||
 		(tsk->sighand->action[sig-1].sa.sa_handler == SIG_DFL);