kern_syscalls.c revision 303975
1100978Srwatson/*- 2100978Srwatson * Copyright (c) 1999 Assar Westerlund 3100978Srwatson * All rights reserved. 4100978Srwatson * 5100978Srwatson * Redistribution and use in source and binary forms, with or without 6100978Srwatson * modification, are permitted provided that the following conditions 7100978Srwatson * are met: 8100978Srwatson * 1. Redistributions of source code must retain the above copyright 9100978Srwatson * notice, this list of conditions and the following disclaimer. 10100978Srwatson * 2. Redistributions in binary form must reproduce the above copyright 11100978Srwatson * notice, this list of conditions and the following disclaimer in the 12100978Srwatson * documentation and/or other materials provided with the distribution. 13100978Srwatson * 14100978Srwatson * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15100978Srwatson * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16100978Srwatson * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17100978Srwatson * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18100978Srwatson * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19100978Srwatson * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20100978Srwatson * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21100978Srwatson * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22100978Srwatson * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23100978Srwatson * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24100978Srwatson * SUCH DAMAGE. 25100978Srwatson */ 26100978Srwatson 27100978Srwatson#include <sys/cdefs.h> 28100978Srwatson__FBSDID("$FreeBSD: releng/11.0/sys/kern/kern_syscalls.c 284215 2015-06-10 10:48:12Z mjg $"); 29100978Srwatson 30100978Srwatson#include <sys/param.h> 31100978Srwatson#include <sys/kernel.h> 32100978Srwatson#include <sys/lock.h> 33100978Srwatson#include <sys/module.h> 34100978Srwatson#include <sys/mutex.h> 35100978Srwatson#include <sys/proc.h> 36100978Srwatson#include <sys/resourcevar.h> 37100978Srwatson#include <sys/sx.h> 38100978Srwatson#include <sys/syscall.h> 39100978Srwatson#include <sys/sysent.h> 40100978Srwatson#include <sys/sysproto.h> 41100978Srwatson#include <sys/systm.h> 42100978Srwatson#include <machine/atomic.h> 43100978Srwatson 44100978Srwatson/* 45100978Srwatson * Acts like "nosys" but can be identified in sysent for dynamic call 46100978Srwatson * number assignment for a limited number of calls. 47100978Srwatson * 48101826Srwatson * Place holder for system call slots reserved for loadable modules. 49101826Srwatson */ 50100978Srwatsonint 51100978Srwatsonlkmnosys(struct thread *td, struct nosys_args *args) 52100978Srwatson{ 53100978Srwatson 54100978Srwatson return (nosys(td, args)); 55100978Srwatson} 56100978Srwatson 57100978Srwatsonint 58100978Srwatsonlkmressys(struct thread *td, struct nosys_args *args) 59100978Srwatson{ 60100978Srwatson 61100978Srwatson return (nosys(td, args)); 62100978Srwatson} 63102123Srwatson 64102123Srwatsonstatic void 65102123Srwatsonsyscall_thread_drain(struct sysent *se) 66102123Srwatson{ 67102123Srwatson u_int32_t cnt, oldcnt; 68100978Srwatson 69100978Srwatson do { 70100978Srwatson oldcnt = se->sy_thrcnt; 71100978Srwatson KASSERT((oldcnt & SY_THR_STATIC) == 0, 72100978Srwatson ("drain on static syscall")); 73100978Srwatson cnt = oldcnt | SY_THR_DRAINING; 74100978Srwatson } while (atomic_cmpset_acq_32(&se->sy_thrcnt, oldcnt, cnt) == 0); 75100978Srwatson while (atomic_cmpset_32(&se->sy_thrcnt, SY_THR_DRAINING, 76100978Srwatson SY_THR_ABSENT) == 0) 77100978Srwatson pause("scdrn", hz/2); 78100978Srwatson} 79100978Srwatson 80100978Srwatsonint 81100978Srwatsonsyscall_thread_enter(struct thread *td, struct sysent *se) 82100978Srwatson{ 83100978Srwatson u_int32_t cnt, oldcnt; 84100978Srwatson 85100978Srwatson do { 86100978Srwatson oldcnt = se->sy_thrcnt; 87100978Srwatson if ((oldcnt & SY_THR_STATIC) != 0) 88100978Srwatson return (0); 89100978Srwatson if ((oldcnt & (SY_THR_DRAINING | SY_THR_ABSENT)) != 0) 90100978Srwatson return (ENOSYS); 91100978Srwatson cnt = oldcnt + SY_THR_INCR; 92100978Srwatson } while (atomic_cmpset_acq_32(&se->sy_thrcnt, oldcnt, cnt) == 0); 93100978Srwatson return (0); 94100978Srwatson} 95100978Srwatson 96100978Srwatsonvoid 97100978Srwatsonsyscall_thread_exit(struct thread *td, struct sysent *se) 98100978Srwatson{ 99100978Srwatson u_int32_t cnt, oldcnt; 100100978Srwatson 101100978Srwatson do { 102100978Srwatson oldcnt = se->sy_thrcnt; 103100978Srwatson if ((oldcnt & SY_THR_STATIC) != 0) 104100978Srwatson return; 105100978Srwatson cnt = oldcnt - SY_THR_INCR; 106100978Srwatson } while (atomic_cmpset_rel_32(&se->sy_thrcnt, oldcnt, cnt) == 0); 107100978Srwatson} 108100978Srwatson 109100978Srwatsonint 110100978Srwatsonsyscall_register(int *offset, struct sysent *new_sysent, 111100978Srwatson struct sysent *old_sysent, int flags) 112100978Srwatson{ 113100978Srwatson int i; 114100978Srwatson 115100978Srwatson if ((flags & ~SY_THR_STATIC) != 0) 116100978Srwatson return (EINVAL); 117100978Srwatson 118100978Srwatson if (*offset == NO_SYSCALL) { 119100978Srwatson for (i = 1; i < SYS_MAXSYSCALL; ++i) 120100978Srwatson if (sysent[i].sy_call == (sy_call_t *)lkmnosys) 121100978Srwatson break; 122100978Srwatson if (i == SYS_MAXSYSCALL) 123100978Srwatson return (ENFILE); 124100978Srwatson *offset = i; 125100978Srwatson } else if (*offset < 0 || *offset >= SYS_MAXSYSCALL) 126100978Srwatson return (EINVAL); 127100978Srwatson else if (sysent[*offset].sy_call != (sy_call_t *)lkmnosys && 128100978Srwatson sysent[*offset].sy_call != (sy_call_t *)lkmressys) 129100978Srwatson return (EEXIST); 130100978Srwatson 131100978Srwatson KASSERT(sysent[*offset].sy_thrcnt == SY_THR_ABSENT, 132100978Srwatson ("dynamic syscall is not protected")); 133100978Srwatson *old_sysent = sysent[*offset]; 134100978Srwatson new_sysent->sy_thrcnt = SY_THR_ABSENT; 135100978Srwatson sysent[*offset] = *new_sysent; 136100978Srwatson atomic_store_rel_32(&sysent[*offset].sy_thrcnt, flags); 137100978Srwatson return (0); 138100978Srwatson} 139100978Srwatson 140100978Srwatsonint 141100978Srwatsonsyscall_deregister(int *offset, struct sysent *old_sysent) 142100978Srwatson{ 143100978Srwatson struct sysent *se; 144100978Srwatson 145100978Srwatson if (*offset == 0) 146100978Srwatson return (0); /* XXX? */ 147100978Srwatson 148100978Srwatson se = &sysent[*offset]; 149100978Srwatson if ((se->sy_thrcnt & SY_THR_STATIC) != 0) 150100978Srwatson return (EINVAL); 151100978Srwatson syscall_thread_drain(se); 152100978Srwatson sysent[*offset] = *old_sysent; 153100978Srwatson return (0); 154100978Srwatson} 155100978Srwatson 156100978Srwatsonint 157100978Srwatsonsyscall_module_handler(struct module *mod, int what, void *arg) 158100978Srwatson{ 159100978Srwatson struct syscall_module_data *data = arg; 160100978Srwatson modspecific_t ms; 161100978Srwatson int error; 162100978Srwatson 163100978Srwatson switch (what) { 164100978Srwatson case MOD_LOAD: 165100978Srwatson error = syscall_register(data->offset, data->new_sysent, 166100978Srwatson &data->old_sysent, data->flags); 167100978Srwatson if (error) { 168100978Srwatson /* Leave a mark so we know to safely unload below. */ 169100978Srwatson data->offset = NULL; 170100978Srwatson return (error); 171100978Srwatson } 172100978Srwatson ms.intval = *data->offset; 173100978Srwatson MOD_XLOCK; 174102123Srwatson module_setspecific(mod, &ms); 175100978Srwatson MOD_XUNLOCK; 176100978Srwatson if (data->chainevh) 177100978Srwatson error = data->chainevh(mod, what, data->chainarg); 178100978Srwatson return (error); 179100978Srwatson case MOD_UNLOAD: 180100978Srwatson /* 181100978Srwatson * MOD_LOAD failed, so just return without calling the 182100978Srwatson * chained handler since we didn't pass along the MOD_LOAD 183100978Srwatson * event. 184100978Srwatson */ 185100978Srwatson if (data->offset == NULL) 186100978Srwatson return (0); 187100978Srwatson if (data->chainevh) { 188100978Srwatson error = data->chainevh(mod, what, data->chainarg); 189100978Srwatson if (error) 190100978Srwatson return error; 191100978Srwatson } 192100978Srwatson error = syscall_deregister(data->offset, &data->old_sysent); 193100978Srwatson return (error); 194100978Srwatson default: 195100978Srwatson if (data->chainevh) 196100978Srwatson return (data->chainevh(mod, what, data->chainarg)); 197100978Srwatson return (EOPNOTSUPP); 198100978Srwatson } 199100978Srwatson 200100978Srwatson /* NOTREACHED */ 201100978Srwatson} 202100978Srwatson 203104338Srwatsonint 204100978Srwatsonsyscall_helper_register(struct syscall_helper_data *sd, int flags) 205100978Srwatson{ 206100978Srwatson struct syscall_helper_data *sd1; 207100978Srwatson int error; 208100978Srwatson 209100978Srwatson for (sd1 = sd; sd1->syscall_no != NO_SYSCALL; sd1++) { 210100978Srwatson error = syscall_register(&sd1->syscall_no, &sd1->new_sysent, 211100978Srwatson &sd1->old_sysent, flags); 212100978Srwatson if (error != 0) { 213100978Srwatson syscall_helper_unregister(sd); 214100978Srwatson return (error); 215100978Srwatson } 216100978Srwatson sd1->registered = 1; 217100978Srwatson } 218100978Srwatson return (0); 219100978Srwatson} 220100978Srwatson 221100978Srwatsonint 222100978Srwatsonsyscall_helper_unregister(struct syscall_helper_data *sd) 223104541Srwatson{ 224100978Srwatson struct syscall_helper_data *sd1; 225104541Srwatson 226100978Srwatson for (sd1 = sd; sd1->registered != 0; sd1++) { 227100978Srwatson syscall_deregister(&sd1->syscall_no, &sd1->old_sysent); 228100978Srwatson sd1->registered = 0; 229100978Srwatson } 230100978Srwatson return (0); 231100978Srwatson} 232100978Srwatson