/*-
* Copyright (c) 2008 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software developed for The NetBSD Foundation
* by Andrew Doran.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Restart the syscall if we interrupted a module unload that
* failed. Acquiring kernconfig_lock delays us until any unload
* has been completed or rolled back.
*/
kernconfig_lock();
sy = l->l_sysent;
if (sy->sy_call != sys_nomodule) {
kernconfig_unlock();
return ERESTART;
}
/*
* Try to autoload a module to satisfy the request. If it
* works, retry the request.
*/
em = l->l_proc->p_emul;
code = sy - em->e_sysent;
int
syscall_establish(const struct emul *em, const struct syscall_package *sp)
{
struct sysent *sy;
int i;
KASSERT(kernconfig_is_held());
if (em == NULL) {
em = &emul_netbsd;
}
sy = em->e_sysent;
/*
* Ensure that all preconditions are valid, since this is
* an all or nothing deal. Once a system call is entered,
* it can become busy and we could be unable to remove it
* on error.
*/
for (i = 0; sp[i].sp_call != NULL; i++) {
if (sp[i].sp_code >= SYS_NSYSENT)
return EINVAL;
if (sy[sp[i].sp_code].sy_call != sys_nomodule &&
sy[sp[i].sp_code].sy_call != sys_nosys) {
#ifdef DIAGNOSTIC
printf("syscall %d is busy\n", sp[i].sp_code);
#endif
return EBUSY;
}
}
/* Everything looks good, patch them in. */
for (i = 0; sp[i].sp_call != NULL; i++) {
sy[sp[i].sp_code].sy_call = sp[i].sp_call;
}
return 0;
}
int
syscall_disestablish(const struct emul *em, const struct syscall_package *sp)
{
struct sysent *sy;
const uint32_t *sb;
lwp_t *l;
int i;
KASSERT(kernconfig_is_held());
if (em == NULL) {
em = &emul_netbsd;
}
sy = em->e_sysent;
sb = em->e_nomodbits;
/*
* First, patch the system calls to sys_nomodule or sys_nosys
* to gate further activity.
*/
for (i = 0; sp[i].sp_call != NULL; i++) {
KASSERT(sy[sp[i].sp_code].sy_call == sp[i].sp_call);
sy[sp[i].sp_code].sy_call =
sb[sp[i].sp_code / 32] & (1 << (sp[i].sp_code % 32)) ?
sys_nomodule : sys_nosys;
}
/*
* Run a cross call to cycle through all CPUs. This does two
* things: lock activity provides a barrier and makes our update
* of sy_call visible to all CPUs, and upon return we can be sure
* that we see pertinent values of l_sysent posted by remote CPUs.
*/
xc_barrier(0);
/*
* Now it's safe to check l_sysent. Run through all LWPs and see
* if anyone is still using the system call.
*/
for (i = 0; sp[i].sp_call != NULL; i++) {
mutex_enter(&proc_lock);
LIST_FOREACH(l, &alllwp, l_list) {
if (l->l_sysent == &sy[sp[i].sp_code]) {
break;
}
}
mutex_exit(&proc_lock);
if (l == NULL) {
continue;
}
/*
* We lose: one or more calls are still in use. Put back
* the old entrypoints and act like nothing happened.
* When we drop kernconfig_lock, any system calls held in
* sys_nomodule() will be restarted.
*/
for (i = 0; sp[i].sp_call != NULL; i++) {
sy[sp[i].sp_code].sy_call = sp[i].sp_call;
}
return EBUSY;
}
return 0;
}
/*
* Return true if system call tracing is enabled for the specified process.
*/
bool
trace_is_enabled(struct proc *p)
{
#ifdef SYSCALL_DEBUG
return (true);
#endif
#ifdef KTRACE
if (ISSET(p->p_traceflag, (KTRFAC_SYSCALL | KTRFAC_SYSRET)))
return (true);
#endif
#ifdef PTRACE
if (ISSET(p->p_slflag, PSL_SYSCALL))
return (true);
#endif
return (false);
}
/*
* Start trace of particular system call. If process is being traced,
* this routine is called by MD syscall dispatch code just before
* a system call is actually executed.
*/
int
trace_enter(register_t code, const struct sysent *sy, const void *args)
{
int error = 0;
#if defined(PTRACE) || defined(KDTRACE_HOOKS)
struct proc *p = curlwp->l_proc;
#endif
#ifdef KDTRACE_HOOKS
if (sy->sy_entry) {
struct emul *e = p->p_emul;
if (e->e_dtrace_syscall)
(*e->e_dtrace_syscall)(sy->sy_entry, code, sy, args,
NULL, 0);
}
#endif
#ifdef PTRACE
if ((p->p_slflag & (PSL_SYSCALL|PSL_TRACED)) ==
(PSL_SYSCALL|PSL_TRACED)) {
proc_stoptrace(TRAP_SCE, code, args, NULL, 0);
if (curlwp->l_proc->p_slflag & PSL_SYSCALLEMU) {
/* tracer will emulate syscall for us */
error = EJUSTRETURN;
}
}
#endif
return error;
}
/*
* End trace of particular system call. If process is being traced,
* this routine is called by MD syscall dispatch code just after
* a system call finishes.
* MD caller guarantees the passed 'code' is within the supported
* system call number range for emulation the process runs under.
*/
void
trace_exit(register_t code, const struct sysent *sy, const void *args,
register_t rval[], int error)
{
#if defined(PTRACE) || defined(KDTRACE_HOOKS)
struct proc *p = curlwp->l_proc;
#endif
#ifdef KDTRACE_HOOKS
if (sy->sy_return) {
struct emul *e = p->p_emul;
if (e->e_dtrace_syscall)
(*p->p_emul->e_dtrace_syscall)(sy->sy_return, code, sy,
args, rval, error);
}
#endif
