# This is Blaisorblade's sysemu patch for UML, cleaned up some, and with
# support added for tt mode.  This adds support to UML for Laurent Vivier's
# context-switch-reducing sysemu patch.
Index: um/arch/um/include/ptrace_user.h
===================================================================
--- um.orig/arch/um/include/ptrace_user.h	2004-09-10 12:12:24.000000000 -0400
+++ um/arch/um/include/ptrace_user.h	2004-09-10 12:13:06.000000000 -0400
@@ -8,6 +8,13 @@
 
 #include "sysdep/ptrace_user.h"
 
+/* syscall emulation path in ptrace */
+#ifndef PTRACE_SYSEMU
+#define PTRACE_SYSEMU 31
+#endif
+
+extern int use_sysemu;
+
 extern int ptrace_getregs(long pid, unsigned long *regs_out);
 extern int ptrace_setregs(long pid, unsigned long *regs_in);
 extern int ptrace_getfpregs(long pid, unsigned long *regs_out);
Index: um/arch/um/kernel/process.c
===================================================================
--- um.orig/arch/um/kernel/process.c	2004-09-10 12:12:24.000000000 -0400
+++ um/arch/um/kernel/process.c	2004-09-10 12:13:06.000000000 -0400
@@ -19,6 +19,7 @@
 #include <asm/sigcontext.h>
 #include <asm/unistd.h>
 #include <asm/page.h>
+#include <asm/user.h>
 #include "user_util.h"
 #include "kern_util.h"
 #include "user.h"
@@ -185,6 +186,8 @@
 		panic("check_ptrace : munmap failed, errno = %d", errno);
 }
 
+int use_sysemu = 0;
+
 void __init check_ptrace(void)
 {
 	void *stack;
@@ -217,6 +220,34 @@
 	}
 	stop_ptraced_child(pid, stack, 0);
 	printk("OK\n");
+
+	printk("Checking syscall emulation patch for ptrace...");
+	pid = start_ptraced_child(&stack);
+	if(ptrace(PTRACE_SYSEMU, pid, 0, 0) >= 0) {
+		CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
+		if(n < 0)
+			panic("check_ptrace : wait failed, errno = %d", errno);
+
+		if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
+			panic("check_ptrace : expected SIGTRAP, "
+			      "got status = %d", status);
+
+		
+		n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_RET_OFFSET,
+			   os_getpid());
+		if(n < 0)
+			panic("check_ptrace : failed to modify system "
+			      "call return, errno = %d", errno);
+
+		stop_ptraced_child(pid, stack, 0);
+
+		printk("OK\n");
+		use_sysemu = 1;
+	}
+	else {
+		printk("missing\n");
+		stop_ptraced_child(pid, stack, 1);
+	}
 }
 
 int run_kernel_thread(int (*fn)(void *), void *arg, void **jmp_ptr)
Index: um/arch/um/kernel/skas/process.c
===================================================================
--- um.orig/arch/um/kernel/skas/process.c	2004-09-10 12:12:24.000000000 -0400
+++ um/arch/um/kernel/skas/process.c	2004-09-10 12:13:06.000000000 -0400
@@ -67,22 +67,25 @@
 		return;
 	}
 
+	handle_syscall(regs);
+	if(use_sysemu)
+		return;
+
 	err = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_NR_OFFSET, __NR_getpid);
 	if(err < 0)
-	        panic("handle_trap - nullifying syscall failed errno = %d\n", 
+		panic("handle_trap - nullifying syscall failed, errno = %d\n",
 		      errno);
 
 	err = ptrace(PTRACE_SYSCALL, pid, 0, 0);
 	if(err < 0)
-	        panic("handle_trap - continuing to end of syscall failed, "
+		panic("handle_trap - continuing to end of syscall failed, "
 		      "errno = %d\n", errno);
 
 	CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED));
-	if((err < 0) || !WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
+	if((err < 0) || !WIFSTOPPED(status) || 
+	   (WSTOPSIG(status) != SIGTRAP))
 		panic("handle_trap - failed to wait at end of syscall, "
 		      "errno = %d, status = %d\n", errno, status);
-
-	handle_syscall(regs);
 }
 
 static int userspace_tramp(void *arg)
@@ -134,11 +137,12 @@
 
 void userspace(union uml_pt_regs *regs)
 {
-	int err, status, op, pid = userspace_pid[0];
+	int err, status, op, do_syscall, pid = userspace_pid[0];
 
+	do_syscall = use_sysemu ? PTRACE_SYSEMU : PTRACE_SYSCALL;
 	restore_registers(regs);
 		
-	err = ptrace(PTRACE_SYSCALL, pid, 0, 0);
+	err = ptrace(do_syscall, pid, 0, 0);
 	if(err)
 		panic("userspace - PTRACE_SYSCALL failed, errno = %d\n", 
 		       errno);
@@ -176,8 +180,7 @@
 
 		restore_registers(regs);
 
-		op = singlestepping_skas() ? PTRACE_SINGLESTEP : 
-			PTRACE_SYSCALL;
+		op = singlestepping_skas() ? PTRACE_SINGLESTEP : do_syscall;
 		err = ptrace(op, pid, 0, 0);
 		if(err)
 			panic("userspace - PTRACE_SYSCALL failed, "
Index: um/arch/um/kernel/tt/syscall_user.c
===================================================================
--- um.orig/arch/um/kernel/tt/syscall_user.c	2004-09-10 12:12:24.000000000 -0400
+++ um/arch/um/kernel/tt/syscall_user.c	2004-09-10 12:13:06.000000000 -0400
@@ -70,6 +70,9 @@
 	   ((unsigned long *) PT_IP(proc_regs) <= &_etext))
 		tracer_panic("I'm tracing myself and I can't get out");
 
+	if(use_sysemu) 
+		return(1);
+
 	if(ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_NR_OFFSET, 
 		  __NR_getpid) < 0)
 		tracer_panic("do_syscall : Nullifying syscall failed, "
Index: um/arch/um/kernel/tt/tracer.c
===================================================================
--- um.orig/arch/um/kernel/tt/tracer.c	2004-09-10 12:12:24.000000000 -0400
+++ um/arch/um/kernel/tt/tracer.c	2004-09-10 12:13:06.000000000 -0400
@@ -184,6 +184,7 @@
 	unsigned long eip = 0;
 	int status, pid = 0, sig = 0, cont_type, tracing = 0, op = 0;
 	int last_index, proc_id = 0, n, err, old_tracing = 0, strace = 0;
+	int cont_syscall;
 
 	capture_signal_stack();
 	signal(SIGPIPE, SIG_IGN);
@@ -297,6 +298,8 @@
 			tracing = is_tracing(task);
 			old_tracing = tracing;
 
+			cont_syscall = use_sysemu ? PTRACE_SYSEMU : 
+				PTRACE_SYSCALL;
 			switch(sig){
 			case SIGUSR1:
 				sig = 0;
@@ -330,7 +333,8 @@
 					continue;
 				}
 				tracing = 0;
-				if(do_syscall(task, pid)) sig = SIGUSR2;
+				if(do_syscall(task, pid))
+					sig = SIGUSR2;
 				else clear_singlestep(task);
 				break;
 			case SIGPROF:
@@ -369,7 +373,7 @@
 			if(tracing){
 				if(singlestepping_tt(task))
 					cont_type = PTRACE_SINGLESTEP;
-				else cont_type = PTRACE_SYSCALL;
+				else cont_type = cont_syscall;
 			}
 			else cont_type = PTRACE_CONT;