Atomic insertion/removal of groups of system call vectors at runtime with
a basic facility for rollback. Proposed on tech-kern@.
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ad
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307004b54f
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119366618e
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@ -1,4 +1,4 @@
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/* $NetBSD: kern_stub.c,v 1.11 2008/10/15 16:03:29 wrstuden Exp $ */
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/* $NetBSD: kern_stub.c,v 1.12 2008/11/12 14:29:31 ad Exp $ */
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/*-
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* Copyright (c) 2007, 2008 The NetBSD Foundation, Inc.
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@ -62,7 +62,7 @@
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: kern_stub.c,v 1.11 2008/10/15 16:03:29 wrstuden Exp $");
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__KERNEL_RCSID(0, "$NetBSD: kern_stub.c,v 1.12 2008/11/12 14:29:31 ad Exp $");
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#include "opt_ptrace.h"
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#include "opt_ktrace.h"
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@ -72,10 +72,13 @@ __KERNEL_RCSID(0, "$NetBSD: kern_stub.c,v 1.11 2008/10/15 16:03:29 wrstuden Exp
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#include <sys/kernel.h>
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#include <sys/proc.h>
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#include <sys/signalvar.h>
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#include <sys/syscall.h>
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#include <sys/syscallargs.h>
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#include <sys/syscallvar.h>
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#include <sys/ktrace.h>
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#include <sys/intr.h>
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#include <sys/cpu.h>
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#include <sys/module.h>
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/*
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* Nonexistent system call-- signal process (may want to handle it). Flag
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@ -160,7 +163,6 @@ cpu_kpreempt_disabled(void)
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# endif
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#endif /* !__HAVE_PREEMPTION */
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/* ARGSUSED */
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int
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sys_nosys(struct lwp *l, const void *v, register_t *retval)
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{
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@ -171,6 +173,65 @@ sys_nosys(struct lwp *l, const void *v, register_t *retval)
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return ENOSYS;
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}
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int
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sys_nomodule(struct lwp *l, const void *v, register_t *retval)
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{
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#ifdef MODULAR
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static struct {
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u_int al_code;
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const char *al_module;
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} const autoload[] = {
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{ SYS__ksem_init, "ksem" },
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{ SYS__ksem_open, "ksem" },
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{ SYS__ksem_unlink, "ksem" },
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{ SYS__ksem_close, "ksem" },
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{ SYS__ksem_post, "ksem" },
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{ SYS__ksem_wait, "ksem" },
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{ SYS__ksem_trywait, "ksem" },
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{ SYS__ksem_getvalue, "ksem" },
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{ SYS__ksem_destroy, "ksem" },
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};
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const struct sysent *sy;
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const struct emul *em;
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int code, i;
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/*
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* Restart the syscall if we interrupted a module unload that
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* failed. Acquiring module_lock delays us until any unload
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* has been completed or rolled back.
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*/
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mutex_enter(&module_lock);
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sy = l->l_sysent;
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if (sy->sy_call != sys_nomodule) {
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mutex_exit(&module_lock);
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return ERESTART;
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}
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/*
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* Try to autoload a module to satisfy the request. If it
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* works, retry the request.
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*/
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em = l->l_proc->p_emul;
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if (em == &emul_netbsd) {
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code = sy - em->e_sysent;
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for (i = 0; i < __arraycount(autoload); i++) {
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if (autoload[i].al_code != code) {
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continue;
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}
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if (module_autoload(autoload[i].al_module,
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MODULE_CLASS_ANY) != 0 ||
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sy->sy_call == sys_nomodule) {
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break;
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}
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mutex_exit(&module_lock);
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return ERESTART;
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}
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}
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mutex_exit(&module_lock);
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#endif /* MODULAR */
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return sys_nosys(l, v, retval);
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}
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/*
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* Unsupported device function (e.g. writing to read-only device).
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*/
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@ -1,4 +1,4 @@
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/* $NetBSD: kern_subr.c,v 1.193 2008/11/11 06:46:44 dyoung Exp $ */
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/* $NetBSD: kern_subr.c,v 1.194 2008/11/12 14:29:31 ad Exp $ */
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/*-
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* Copyright (c) 1997, 1998, 1999, 2002, 2007, 2008 The NetBSD Foundation, Inc.
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@ -79,7 +79,7 @@
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: kern_subr.c,v 1.193 2008/11/11 06:46:44 dyoung Exp $");
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__KERNEL_RCSID(0, "$NetBSD: kern_subr.c,v 1.194 2008/11/12 14:29:31 ad Exp $");
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#include "opt_ddb.h"
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#include "opt_md.h"
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@ -105,6 +105,9 @@ __KERNEL_RCSID(0, "$NetBSD: kern_subr.c,v 1.193 2008/11/11 06:46:44 dyoung Exp $
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#include <sys/fcntl.h>
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#include <sys/kauth.h>
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#include <sys/vnode.h>
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#include <sys/syscallvar.h>
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#include <sys/xcall.h>
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#include <sys/module.h>
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#include <uvm/uvm_extern.h>
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@ -1330,3 +1333,98 @@ trace_exit(register_t code, register_t rval[], int error)
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process_stoptrace();
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#endif
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}
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int
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syscall_establish(const struct emul *em, const struct syscall_package *sp)
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{
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struct sysent *sy;
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int i;
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KASSERT(mutex_owned(&module_lock));
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if (em == NULL) {
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em = &emul_netbsd;
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}
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sy = em->e_sysent;
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/*
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* Ensure that all preconditions are valid, since this is
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* an all or nothing deal. Once a system call is entered,
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* it can become busy and we could be unable to remove it
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* on error.
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*/
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for (i = 0; sp[i].sp_call != NULL; i++) {
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if (sy[sp[i].sp_code].sy_call != sys_nomodule) {
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return EBUSY;
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}
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}
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/* Everything looks good, patch them in. */
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for (i = 0; sp[i].sp_call != NULL; i++) {
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sy[sp[i].sp_code].sy_call = sp[i].sp_call;
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}
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return 0;
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}
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int
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syscall_disestablish(const struct emul *em, const struct syscall_package *sp)
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{
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struct sysent *sy;
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uint64_t where;
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lwp_t *l;
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int i;
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KASSERT(mutex_owned(&module_lock));
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if (em == NULL) {
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em = &emul_netbsd;
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}
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sy = em->e_sysent;
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/*
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* First, patch the system calls to sys_nomodule to gate further
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* activity.
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*/
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for (i = 0; sp[i].sp_call != NULL; i++) {
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KASSERT(sy[sp[i].sp_code].sy_call == sp[i].sp_call);
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sy[sp[i].sp_code].sy_call = sys_nomodule;
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}
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/*
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* Run a cross call to cycle through all CPUs. This does two
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* things: lock activity provides a barrier and makes our update
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* of sy_call visible to all CPUs, and upon return we can be sure
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* that we see pertinent values of l_sysent posted by remote CPUs.
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*/
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where = xc_broadcast(0, (xcfunc_t)nullop, NULL, NULL);
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xc_wait(where);
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/*
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* Now it's safe to check l_sysent. Run through all LWPs and see
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* if anyone is still using the system call.
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*/
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for (i = 0; sp[i].sp_call != NULL; i++) {
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mutex_enter(proc_lock);
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LIST_FOREACH(l, &alllwp, l_list) {
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if (l->l_sysent == &sy[sp[i].sp_code]) {
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break;
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}
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}
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mutex_exit(proc_lock);
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if (l == NULL) {
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continue;
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}
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/*
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* We lose: one or more calls are still in use. Put back
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* the old entrypoints and act like nothing happened.
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* When we drop module_lock, any system calls held in
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* sys_nomodule() will be restarted.
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*/
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for (i = 0; sp[i].sp_call != NULL; i++) {
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sy[sp[i].sp_code].sy_call = sp[i].sp_call;
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}
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return EBUSY;
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}
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return 0;
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}
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@ -1,5 +1,5 @@
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#! /bin/sh -
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# $NetBSD: makesyscalls.sh,v 1.73 2008/10/13 18:16:33 pooka Exp $
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# $NetBSD: makesyscalls.sh,v 1.74 2008/11/12 14:29:31 ad Exp $
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#
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# Copyright (c) 1994, 1996, 2000 Christopher G. Demetriou
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# All rights reserved.
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@ -345,6 +345,12 @@ function parseline() {
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sycall_flags = "SYCALL_INDIRECT | " sycall_flags
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f++
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}
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if ($f == "MODULAR") { # registered at runtime
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modular = 1
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f++
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} else {
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modular = 0;
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}
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if ($f == "RUMP") {
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rumpable = 1
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f++
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@ -497,7 +503,9 @@ function putent(type, compatwrap) {
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} else {
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printf("ns(struct %s%s_args), ", compatwrap_, funcname) > sysent
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}
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if (compatwrap == "")
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if (modular)
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wfn = "(sy_call_t *)sys_nomodule";
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else if (compatwrap == "")
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wfn = "(sy_call_t *)" funcname;
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else
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wfn = "(sy_call_t *)" compatwrap "(" funcname ")";
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/* $NetBSD: syscallvar.h,v 1.2 2008/10/21 12:22:00 ad Exp $ */
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/* $NetBSD: syscallvar.h,v 1.3 2008/11/12 14:29:31 ad Exp $ */
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/*-
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* Copyright (c) 2008 The NetBSD Foundation, Inc.
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@ -39,6 +39,18 @@
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#include <sys/systm.h>
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#include <sys/proc.h>
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extern const struct emul emul_netbsd;
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struct syscall_package {
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u_short sp_code;
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u_short sp_flags;
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sy_call_t *sp_call;
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};
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void syscall_init(void);
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int syscall_establish(const struct emul *, const struct syscall_package *);
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int syscall_disestablish(const struct emul *, const struct syscall_package *);
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static inline int
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sy_call(const struct sysent *sy, struct lwp *l, const void *uap,
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register_t *rval)
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/* $NetBSD: systm.h,v 1.229 2008/11/12 12:36:28 ad Exp $ */
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/* $NetBSD: systm.h,v 1.230 2008/11/12 14:29:31 ad Exp $ */
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/*-
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* Copyright (c) 1982, 1988, 1991, 1993
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@ -157,6 +157,7 @@ void *hashinit(u_int, enum hashtype, bool, u_long *);
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void hashdone(void *, enum hashtype, u_long);
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int seltrue(dev_t, int, struct lwp *);
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int sys_nosys(struct lwp *, const void *, register_t *);
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int sys_nomodule(struct lwp *, const void *, register_t *);
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void aprint_normal(const char *, ...)
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__attribute__((__format__(__printf__,1,2)));
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