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> 34284214Smjg#include <sys/mutex.h> 35284214Smjg#include <sys/proc.h> 36284215Smjg#include <sys/resourcevar.h> 3792547Sarr#include <sys/sx.h> 38183156Sjhb#include <sys/syscall.h> 39183156Sjhb#include <sys/sysent.h> 40183156Sjhb#include <sys/sysproto.h> 41209579Skib#include <sys/systm.h> 42209579Skib#include <machine/atomic.h> 4342433Sdfr 4442756Speter/* 45183156Sjhb * Acts like "nosys" but can be identified in sysent for dynamic call 46183156Sjhb * number assignment for a limited number of calls. 47183156Sjhb * 4842756Speter * Place holder for system call slots reserved for loadable modules. 49183156Sjhb */ 5042433Sdfrint 5183366Sjulianlkmnosys(struct thread *td, struct nosys_args *args) 5242756Speter{ 53183156Sjhb 54183156Sjhb return (nosys(td, args)); 5542756Speter} 5642756Speter 5742756Speterint 5883366Sjulianlkmressys(struct thread *td, struct nosys_args *args) 5969449Salfred{ 60183156Sjhb 61183156Sjhb return (nosys(td, args)); 6269449Salfred} 6369449Salfred 64209579Skibstatic void 65209579Skibsyscall_thread_drain(struct sysent *se) 66209579Skib{ 67209579Skib u_int32_t cnt, oldcnt; 68209579Skib 69209579Skib do { 70209579Skib oldcnt = se->sy_thrcnt; 71209579Skib KASSERT((oldcnt & SY_THR_STATIC) == 0, 72209579Skib ("drain on static syscall")); 73209579Skib cnt = oldcnt | SY_THR_DRAINING; 74209579Skib } while (atomic_cmpset_acq_32(&se->sy_thrcnt, oldcnt, cnt) == 0); 75209579Skib while (atomic_cmpset_32(&se->sy_thrcnt, SY_THR_DRAINING, 76209579Skib SY_THR_ABSENT) == 0) 77209579Skib pause("scdrn", hz/2); 78209579Skib} 79209579Skib 8069449Salfredint 81209579Skibsyscall_thread_enter(struct thread *td, struct sysent *se) 82209579Skib{ 83209579Skib u_int32_t cnt, oldcnt; 84209579Skib 85209579Skib do { 86209579Skib oldcnt = se->sy_thrcnt; 87209579Skib if ((oldcnt & SY_THR_STATIC) != 0) 88209579Skib return (0); 89209579Skib if ((oldcnt & (SY_THR_DRAINING | SY_THR_ABSENT)) != 0) 90209579Skib return (ENOSYS); 91209579Skib cnt = oldcnt + SY_THR_INCR; 92209579Skib } while (atomic_cmpset_acq_32(&se->sy_thrcnt, oldcnt, cnt) == 0); 93209579Skib return (0); 94209579Skib} 95209579Skib 96209579Skibvoid 97209579Skibsyscall_thread_exit(struct thread *td, struct sysent *se) 98209579Skib{ 99209579Skib u_int32_t cnt, oldcnt; 100209579Skib 101209579Skib do { 102209579Skib oldcnt = se->sy_thrcnt; 103209579Skib if ((oldcnt & SY_THR_STATIC) != 0) 104209579Skib return; 105209579Skib cnt = oldcnt - SY_THR_INCR; 106209579Skib } while (atomic_cmpset_rel_32(&se->sy_thrcnt, oldcnt, cnt) == 0); 107209579Skib} 108209579Skib 109209579Skibint 11042433Sdfrsyscall_register(int *offset, struct sysent *new_sysent, 111273707Smjg struct sysent *old_sysent, int flags) 11242433Sdfr{ 113183156Sjhb int i; 11442433Sdfr 115273707Smjg if ((flags & ~SY_THR_STATIC) != 0) 116273707Smjg return (EINVAL); 117273707Smjg 118183156Sjhb if (*offset == NO_SYSCALL) { 119183156Sjhb for (i = 1; i < SYS_MAXSYSCALL; ++i) 120183156Sjhb if (sysent[i].sy_call == (sy_call_t *)lkmnosys) 121183156Sjhb break; 122183156Sjhb if (i == SYS_MAXSYSCALL) 123183156Sjhb return (ENFILE); 124183156Sjhb *offset = i; 125183156Sjhb } else if (*offset < 0 || *offset >= SYS_MAXSYSCALL) 126183156Sjhb return (EINVAL); 127183156Sjhb else if (sysent[*offset].sy_call != (sy_call_t *)lkmnosys && 128183156Sjhb sysent[*offset].sy_call != (sy_call_t *)lkmressys) 129183156Sjhb return (EEXIST); 13042433Sdfr 131209579Skib KASSERT(sysent[*offset].sy_thrcnt == SY_THR_ABSENT, 132209579Skib ("dynamic syscall is not protected")); 133183156Sjhb *old_sysent = sysent[*offset]; 134209579Skib new_sysent->sy_thrcnt = SY_THR_ABSENT; 135183156Sjhb sysent[*offset] = *new_sysent; 136273707Smjg atomic_store_rel_32(&sysent[*offset].sy_thrcnt, flags); 137183156Sjhb return (0); 13842433Sdfr} 13942433Sdfr 14042433Sdfrint 14142433Sdfrsyscall_deregister(int *offset, struct sysent *old_sysent) 14242433Sdfr{ 143273707Smjg struct sysent *se; 144183156Sjhb 145273707Smjg if (*offset == 0) 146273707Smjg return (0); /* XXX? */ 147273707Smjg 148273707Smjg se = &sysent[*offset]; 149273707Smjg if ((se->sy_thrcnt & SY_THR_STATIC) != 0) 150273707Smjg return (EINVAL); 151273707Smjg syscall_thread_drain(se); 152273707Smjg sysent[*offset] = *old_sysent; 153183156Sjhb return (0); 15442433Sdfr} 15542433Sdfr 15642433Sdfrint 15742433Sdfrsyscall_module_handler(struct module *mod, int what, void *arg) 15842433Sdfr{ 159183156Sjhb struct syscall_module_data *data = arg; 160183156Sjhb modspecific_t ms; 161183156Sjhb int error; 16242433Sdfr 163183156Sjhb switch (what) { 164183156Sjhb case MOD_LOAD: 165183156Sjhb error = syscall_register(data->offset, data->new_sysent, 166273953Smjg &data->old_sysent, data->flags); 167183156Sjhb if (error) { 168183156Sjhb /* Leave a mark so we know to safely unload below. */ 169183156Sjhb data->offset = NULL; 170183156Sjhb return (error); 171183156Sjhb } 172183156Sjhb ms.intval = *data->offset; 173183156Sjhb MOD_XLOCK; 174183156Sjhb module_setspecific(mod, &ms); 175183156Sjhb MOD_XUNLOCK; 176183156Sjhb if (data->chainevh) 177183156Sjhb error = data->chainevh(mod, what, data->chainarg); 178183156Sjhb return (error); 179183156Sjhb case MOD_UNLOAD: 180183156Sjhb /* 181183156Sjhb * MOD_LOAD failed, so just return without calling the 182183156Sjhb * chained handler since we didn't pass along the MOD_LOAD 183183156Sjhb * event. 184183156Sjhb */ 185183156Sjhb if (data->offset == NULL) 186183156Sjhb return (0); 187183156Sjhb if (data->chainevh) { 188183156Sjhb error = data->chainevh(mod, what, data->chainarg); 189183156Sjhb if (error) 190183156Sjhb return error; 191183156Sjhb } 192183156Sjhb error = syscall_deregister(data->offset, &data->old_sysent); 193183156Sjhb return (error); 194183156Sjhb default: 195214181Sdelphij if (data->chainevh) 196214181Sdelphij return (data->chainevh(mod, what, data->chainarg)); 197214181Sdelphij return (EOPNOTSUPP); 198183156Sjhb } 19948269Sdfr 200214125Sdelphij /* NOTREACHED */ 20142433Sdfr} 202205321Skib 203205321Skibint 204273707Smjgsyscall_helper_register(struct syscall_helper_data *sd, int flags) 205205321Skib{ 206205321Skib struct syscall_helper_data *sd1; 207205321Skib int error; 208205321Skib 209205321Skib for (sd1 = sd; sd1->syscall_no != NO_SYSCALL; sd1++) { 210205321Skib error = syscall_register(&sd1->syscall_no, &sd1->new_sysent, 211273707Smjg &sd1->old_sysent, flags); 212205321Skib if (error != 0) { 213205321Skib syscall_helper_unregister(sd); 214205321Skib return (error); 215205321Skib } 216205321Skib sd1->registered = 1; 217205321Skib } 218205321Skib return (0); 219205321Skib} 220205321Skib 221205321Skibint 222205321Skibsyscall_helper_unregister(struct syscall_helper_data *sd) 223205321Skib{ 224205321Skib struct syscall_helper_data *sd1; 225205321Skib 226205321Skib for (sd1 = sd; sd1->registered != 0; sd1++) { 227205321Skib syscall_deregister(&sd1->syscall_no, &sd1->old_sysent); 228205321Skib sd1->registered = 0; 229205321Skib } 230205321Skib return (0); 231205321Skib} 232