142433Sdfr/*- 242433Sdfr * Copyright (c) 1999 Assar Westerlund 342433Sdfr * All rights reserved. 442433Sdfr * 542433Sdfr * Redistribution and use in source and binary forms, with or without 642433Sdfr * modification, are permitted provided that the following conditions 742433Sdfr * are met: 842433Sdfr * 1. Redistributions of source code must retain the above copyright 942433Sdfr * notice, this list of conditions and the following disclaimer. 1042433Sdfr * 2. Redistributions in binary form must reproduce the above copyright 1142433Sdfr * notice, this list of conditions and the following disclaimer in the 1242433Sdfr * documentation and/or other materials provided with the distribution. 1342433Sdfr * 1442433Sdfr * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 1542433Sdfr * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 1642433Sdfr * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 1742433Sdfr * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 1842433Sdfr * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 1942433Sdfr * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 2042433Sdfr * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 2142433Sdfr * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 2242433Sdfr * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 2342433Sdfr * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 2442433Sdfr * SUCH DAMAGE. 2542433Sdfr */ 2642433Sdfr 27116182Sobrien#include <sys/cdefs.h> 28116182Sobrien__FBSDID("$FreeBSD$"); 29116182Sobrien 3042433Sdfr#include <sys/param.h> 31209579Skib#include <sys/kernel.h> 3292547Sarr#include <sys/lock.h> 33183156Sjhb#include <sys/module.h> 3492547Sarr#include <sys/sx.h> 35183156Sjhb#include <sys/syscall.h> 36183156Sjhb#include <sys/sysent.h> 37183156Sjhb#include <sys/sysproto.h> 38209579Skib#include <sys/systm.h> 39209579Skib#include <machine/atomic.h> 4042433Sdfr 4142756Speter/* 42183156Sjhb * Acts like "nosys" but can be identified in sysent for dynamic call 43183156Sjhb * number assignment for a limited number of calls. 44183156Sjhb * 4542756Speter * Place holder for system call slots reserved for loadable modules. 46183156Sjhb */ 4742433Sdfrint 4883366Sjulianlkmnosys(struct thread *td, struct nosys_args *args) 4942756Speter{ 50183156Sjhb 51183156Sjhb return (nosys(td, args)); 5242756Speter} 5342756Speter 5442756Speterint 5583366Sjulianlkmressys(struct thread *td, struct nosys_args *args) 5669449Salfred{ 57183156Sjhb 58183156Sjhb return (nosys(td, args)); 5969449Salfred} 6069449Salfred 61209579Skibstatic void 62209579Skibsyscall_thread_drain(struct sysent *se) 63209579Skib{ 64209579Skib u_int32_t cnt, oldcnt; 65209579Skib 66209579Skib do { 67209579Skib oldcnt = se->sy_thrcnt; 68209579Skib KASSERT((oldcnt & SY_THR_STATIC) == 0, 69209579Skib ("drain on static syscall")); 70209579Skib cnt = oldcnt | SY_THR_DRAINING; 71209579Skib } while (atomic_cmpset_acq_32(&se->sy_thrcnt, oldcnt, cnt) == 0); 72209579Skib while (atomic_cmpset_32(&se->sy_thrcnt, SY_THR_DRAINING, 73209579Skib SY_THR_ABSENT) == 0) 74209579Skib pause("scdrn", hz/2); 75209579Skib} 76209579Skib 7769449Salfredint 78209579Skibsyscall_thread_enter(struct thread *td, struct sysent *se) 79209579Skib{ 80209579Skib u_int32_t cnt, oldcnt; 81209579Skib 82209579Skib do { 83209579Skib oldcnt = se->sy_thrcnt; 84209579Skib if ((oldcnt & SY_THR_STATIC) != 0) 85209579Skib return (0); 86209579Skib if ((oldcnt & (SY_THR_DRAINING | SY_THR_ABSENT)) != 0) 87209579Skib return (ENOSYS); 88209579Skib cnt = oldcnt + SY_THR_INCR; 89209579Skib } while (atomic_cmpset_acq_32(&se->sy_thrcnt, oldcnt, cnt) == 0); 90209579Skib return (0); 91209579Skib} 92209579Skib 93209579Skibvoid 94209579Skibsyscall_thread_exit(struct thread *td, struct sysent *se) 95209579Skib{ 96209579Skib u_int32_t cnt, oldcnt; 97209579Skib 98209579Skib do { 99209579Skib oldcnt = se->sy_thrcnt; 100209579Skib if ((oldcnt & SY_THR_STATIC) != 0) 101209579Skib return; 102209579Skib cnt = oldcnt - SY_THR_INCR; 103209579Skib } while (atomic_cmpset_rel_32(&se->sy_thrcnt, oldcnt, cnt) == 0); 104209579Skib} 105209579Skib 106209579Skibint 10742433Sdfrsyscall_register(int *offset, struct sysent *new_sysent, 108183156Sjhb struct sysent *old_sysent) 10942433Sdfr{ 110183156Sjhb int i; 11142433Sdfr 112183156Sjhb if (*offset == NO_SYSCALL) { 113183156Sjhb for (i = 1; i < SYS_MAXSYSCALL; ++i) 114183156Sjhb if (sysent[i].sy_call == (sy_call_t *)lkmnosys) 115183156Sjhb break; 116183156Sjhb if (i == SYS_MAXSYSCALL) 117183156Sjhb return (ENFILE); 118183156Sjhb *offset = i; 119183156Sjhb } else if (*offset < 0 || *offset >= SYS_MAXSYSCALL) 120183156Sjhb return (EINVAL); 121183156Sjhb else if (sysent[*offset].sy_call != (sy_call_t *)lkmnosys && 122183156Sjhb sysent[*offset].sy_call != (sy_call_t *)lkmressys) 123183156Sjhb return (EEXIST); 12442433Sdfr 125209579Skib KASSERT(sysent[*offset].sy_thrcnt == SY_THR_ABSENT, 126209579Skib ("dynamic syscall is not protected")); 127183156Sjhb *old_sysent = sysent[*offset]; 128209579Skib new_sysent->sy_thrcnt = SY_THR_ABSENT; 129183156Sjhb sysent[*offset] = *new_sysent; 130209579Skib atomic_store_rel_32(&sysent[*offset].sy_thrcnt, 0); 131183156Sjhb return (0); 13242433Sdfr} 13342433Sdfr 13442433Sdfrint 13542433Sdfrsyscall_deregister(int *offset, struct sysent *old_sysent) 13642433Sdfr{ 137183156Sjhb 138209579Skib if (*offset) { 139209579Skib syscall_thread_drain(&sysent[*offset]); 140183156Sjhb sysent[*offset] = *old_sysent; 141209579Skib } 142183156Sjhb return (0); 14342433Sdfr} 14442433Sdfr 14542433Sdfrint 14642433Sdfrsyscall_module_handler(struct module *mod, int what, void *arg) 14742433Sdfr{ 148183156Sjhb struct syscall_module_data *data = arg; 149183156Sjhb modspecific_t ms; 150183156Sjhb int error; 15142433Sdfr 152183156Sjhb switch (what) { 153183156Sjhb case MOD_LOAD: 154183156Sjhb error = syscall_register(data->offset, data->new_sysent, 155183156Sjhb &data->old_sysent); 156183156Sjhb if (error) { 157183156Sjhb /* Leave a mark so we know to safely unload below. */ 158183156Sjhb data->offset = NULL; 159183156Sjhb return (error); 160183156Sjhb } 161183156Sjhb ms.intval = *data->offset; 162183156Sjhb MOD_XLOCK; 163183156Sjhb module_setspecific(mod, &ms); 164183156Sjhb MOD_XUNLOCK; 165183156Sjhb if (data->chainevh) 166183156Sjhb error = data->chainevh(mod, what, data->chainarg); 167183156Sjhb return (error); 168183156Sjhb case MOD_UNLOAD: 169183156Sjhb /* 170183156Sjhb * MOD_LOAD failed, so just return without calling the 171183156Sjhb * chained handler since we didn't pass along the MOD_LOAD 172183156Sjhb * event. 173183156Sjhb */ 174183156Sjhb if (data->offset == NULL) 175183156Sjhb return (0); 176183156Sjhb if (data->chainevh) { 177183156Sjhb error = data->chainevh(mod, what, data->chainarg); 178183156Sjhb if (error) 179183156Sjhb return error; 180183156Sjhb } 181183156Sjhb error = syscall_deregister(data->offset, &data->old_sysent); 182183156Sjhb return (error); 183183156Sjhb default: 184214181Sdelphij if (data->chainevh) 185214181Sdelphij return (data->chainevh(mod, what, data->chainarg)); 186214181Sdelphij return (EOPNOTSUPP); 187183156Sjhb } 18848269Sdfr 189214125Sdelphij /* NOTREACHED */ 19042433Sdfr} 191205321Skib 192205321Skibint 193205321Skibsyscall_helper_register(struct syscall_helper_data *sd) 194205321Skib{ 195205321Skib struct syscall_helper_data *sd1; 196205321Skib int error; 197205321Skib 198205321Skib for (sd1 = sd; sd1->syscall_no != NO_SYSCALL; sd1++) { 199205321Skib error = syscall_register(&sd1->syscall_no, &sd1->new_sysent, 200205321Skib &sd1->old_sysent); 201205321Skib if (error != 0) { 202205321Skib syscall_helper_unregister(sd); 203205321Skib return (error); 204205321Skib } 205205321Skib sd1->registered = 1; 206205321Skib } 207205321Skib return (0); 208205321Skib} 209205321Skib 210205321Skibint 211205321Skibsyscall_helper_unregister(struct syscall_helper_data *sd) 212205321Skib{ 213205321Skib struct syscall_helper_data *sd1; 214205321Skib 215205321Skib for (sd1 = sd; sd1->registered != 0; sd1++) { 216205321Skib syscall_deregister(&sd1->syscall_no, &sd1->old_sysent); 217205321Skib sd1->registered = 0; 218205321Skib } 219205321Skib return (0); 220205321Skib} 221