diff -Nrc skas3-linux-2.4.22/Makefile skas4-linux-2.4.22/Makefile
*** skas3-linux-2.4.22/Makefile	Tue Dec  2 21:24:14 2003
--- skas4-linux-2.4.22/Makefile	Tue Dec  2 20:32:41 2003
***************
*** 1,7 ****
  VERSION = 2
  PATCHLEVEL = 4
  SUBLEVEL = 22
! EXTRAVERSION = -skas3
  
  KERNELRELEASE=$(VERSION).$(PATCHLEVEL).$(SUBLEVEL)$(EXTRAVERSION)
  
--- 1,7 ----
  VERSION = 2
  PATCHLEVEL = 4
  SUBLEVEL = 22
! EXTRAVERSION = -sysemu
  
  KERNELRELEASE=$(VERSION).$(PATCHLEVEL).$(SUBLEVEL)$(EXTRAVERSION)
  
diff -Nrc skas3-linux-2.4.22/arch/i386/kernel/entry.S skas4-linux-2.4.22/arch/i386/kernel/entry.S
*** skas3-linux-2.4.22/arch/i386/kernel/entry.S	Fri Jun 13 16:51:29 2003
--- skas4-linux-2.4.22/arch/i386/kernel/entry.S	Tue Dec  2 20:27:41 2003
***************
*** 203,208 ****
--- 203,210 ----
  	pushl %eax			# save orig_eax
  	SAVE_ALL
  	GET_CURRENT(%ebx)
+ 	testb $0x20,tsk_ptrace(%ebx)	# PT_SCEMU
+ 	jne emulatesys
  	testb $0x02,tsk_ptrace(%ebx)	# PT_TRACESYS
  	jne tracesys
  	cmpl $(NR_syscalls),%eax
***************
*** 237,242 ****
--- 239,248 ----
  	jmp restore_all
  
  	ALIGN
+ emulatesys:
+ 	call SYMBOL_NAME(syscall_emulate)
+ 	jmp ret_from_sys_call
+ 	ALIGN
  tracesys:
  	movl $-ENOSYS,EAX(%esp)
  	call SYMBOL_NAME(syscall_trace)
diff -Nrc skas3-linux-2.4.22/arch/i386/kernel/ptrace.c skas4-linux-2.4.22/arch/i386/kernel/ptrace.c
*** skas3-linux-2.4.22/arch/i386/kernel/ptrace.c	Tue Dec  2 21:24:01 2003
--- skas4-linux-2.4.22/arch/i386/kernel/ptrace.c	Tue Dec  2 18:52:10 2003
***************
*** 275,280 ****
--- 275,281 ----
  		  }
  		  break;
  
+ 	case PTRACE_SCEMU: /* continue and replace next syscall */
  	case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
  	case PTRACE_CONT: { /* restart after signal. */
  		long tmp;
***************
*** 282,287 ****
--- 283,292 ----
  		ret = -EIO;
  		if ((unsigned long) data > _NSIG)
  			break;
+ 		if (request == PTRACE_SCEMU)
+ 			child->ptrace |= PT_SCEMU;
+ 		else
+ 			child->ptrace &= ~PT_SCEMU;
  		if (request == PTRACE_SYSCALL)
  			child->ptrace |= PT_TRACESYS;
  		else
***************
*** 320,326 ****
  		ret = -EIO;
  		if ((unsigned long) data > _NSIG)
  			break;
! 		child->ptrace &= ~PT_TRACESYS;
  		if ((child->ptrace & PT_DTRACE) == 0) {
  			/* Spurious delayed TF traps may occur */
  			child->ptrace |= PT_DTRACE;
--- 325,331 ----
  		ret = -EIO;
  		if ((unsigned long) data > _NSIG)
  			break;
! 		child->ptrace &= ~(PT_TRACESYS|PT_SCEMU);
  		if ((child->ptrace & PT_DTRACE) == 0) {
  			/* Spurious delayed TF traps may occur */
  			child->ptrace |= PT_DTRACE;
***************
*** 482,487 ****
--- 487,515 ----
  	return ret;
  }
  
+ asmlinkage void syscall_emulate(void)
+ {
+ 	if ((current->ptrace & (PT_PTRACED|PT_SCEMU)) !=
+ 			(PT_PTRACED|PT_SCEMU))
+ 		return;
+ 	/* the 0x80 provides a way for the tracing parent to distinguish
+ 	   between a syscall stop and SIGTRAP delivery */
+ 	current->exit_code = SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
+ 					? 0x80 : 0);
+ 	current->state = TASK_STOPPED;
+ 	notify_parent(current, SIGCHLD);
+ 	schedule();
+ 	/*
+ 	 * this isn't the same as continuing with a signal, but it will do
+ 	 * for normal use.  strace only continues with a signal if the
+ 	 * stopping signal is not SIGTRAP.  -brl
+ 	 */
+ 	if (current->exit_code) {
+ 		send_sig(current->exit_code, current, 1);
+ 		current->exit_code = 0;
+ 	}
+ }
+ 
  asmlinkage void syscall_trace(void)
  {
  	if ((current->ptrace & (PT_PTRACED|PT_TRACESYS)) !=
diff -Nrc skas3-linux-2.4.22/include/linux/ptrace.h skas4-linux-2.4.22/include/linux/ptrace.h
*** skas3-linux-2.4.22/include/linux/ptrace.h	Sat Sep 15 00:55:17 2001
--- skas4-linux-2.4.22/include/linux/ptrace.h	Tue Dec  2 18:42:55 2003
***************
*** 20,25 ****
--- 20,26 ----
  #define PTRACE_DETACH		0x11
  
  #define PTRACE_SYSCALL		  24
+ #define PTRACE_SCEMU		  25
  
  #include <asm/ptrace.h>
  
diff -Nrc skas3-linux-2.4.22/include/linux/sched.h skas4-linux-2.4.22/include/linux/sched.h
*** skas3-linux-2.4.22/include/linux/sched.h	Fri Jun 13 16:51:39 2003
--- skas4-linux-2.4.22/include/linux/sched.h	Tue Dec  2 20:28:19 2003
***************
*** 444,449 ****
--- 444,450 ----
  #define PT_DTRACE	0x00000004	/* delayed trace (used on m68k, i386) */
  #define PT_TRACESYSGOOD	0x00000008
  #define PT_PTRACE_CAP	0x00000010	/* ptracer can follow suid-exec */
+ #define PT_SCEMU	0x00000020	/* syscall emulation for UML */
  
  #define is_dumpable(tsk)    ((tsk)->task_dumpable && (tsk)->mm && (tsk)->mm->dumpable)