[src/trunk]: src/sys/arch/usermode/dev Make the trampoline only jump once!

[reinoud <reinoud%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/5475b5b53daf
branches:  trunk
changeset: 769435:5475b5b53daf
user:      reinoud <reinoud%NetBSD.org@localhost>
date:      Fri Sep 09 20:14:33 2011 +0000

description:
Make the trampoline only jump once!
All next calls are directed directly to the func specified.

diffstat:

 sys/arch/usermode/dev/cpu.c |  14 ++++++++++----
 1 files changed, 10 insertions(+), 4 deletions(-)

diffs (47 lines):

diff -r 12e8e3f1ae28 -r 5475b5b53daf sys/arch/usermode/dev/cpu.c
--- a/sys/arch/usermode/dev/cpu.c       Fri Sep 09 20:06:04 2011 +0000
+++ b/sys/arch/usermode/dev/cpu.c       Fri Sep 09 20:14:33 2011 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: cpu.c,v 1.43 2011/09/09 20:06:04 reinoud Exp $ */
+/* $NetBSD: cpu.c,v 1.44 2011/09/09 20:14:33 reinoud Exp $ */
 
 /*-
  * Copyright (c) 2007 Jared D. McNeill <jmcneill%invisible.ca@localhost>
@@ -30,7 +30,7 @@
 #include "opt_hz.h"
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: cpu.c,v 1.43 2011/09/09 20:06:04 reinoud Exp $");
+__KERNEL_RCSID(0, "$NetBSD: cpu.c,v 1.44 2011/09/09 20:14:33 reinoud Exp $");
 
 #include <sys/param.h>
 #include <sys/conf.h>
@@ -278,12 +278,18 @@
 }
 
 static void
-cpu_lwp_trampoline(void (*func)(void *), void *arg)
+cpu_lwp_trampoline(ucontext_t *ucp, void (*func)(void *), void *arg)
 {
 #ifdef CPU_DEBUG
        printf("cpu_lwp_trampoline called with func %p, arg %p\n", (void *) func, arg);
 #endif
+       /* init lwp */
        lwp_startup(curcpu()->ci_stash, curlwp);
+
+       /* adjust context so the next switch bypasses the trampoline */
+       thunk_makecontext(ucp, (void (*)(void)) func, 1, arg, NULL, NULL);
+
+       /* issue for the 1st time */
        func(arg);
 }
 
@@ -321,7 +327,7 @@
        pcb2->pcb_ucp.uc_link = &pcb2->pcb_userland_ucp;
        pcb2->pcb_ucp.uc_flags = _UC_STACK | _UC_CPU;
        thunk_makecontext(&pcb2->pcb_ucp, (void (*)(void)) cpu_lwp_trampoline,
-           2, func, arg, NULL);
+           3, &pcb2->pcb_ucp, func, arg);
 
        /* set up the ucontext for the syscall */
        pcb2->pcb_syscall_ucp.uc_flags = _UC_CPU;