| 1 | /* $NetBSD: kern_syscall.c,v 1.14 2015/11/30 23:34:47 pgoyette Exp $ */ |
| 2 | |
| 3 | /*- |
| 4 | * Copyright (c) 2008 The NetBSD Foundation, Inc. |
| 5 | * All rights reserved. |
| 6 | * |
| 7 | * This code is derived from software developed for The NetBSD Foundation |
| 8 | * by Andrew Doran. |
| 9 | * |
| 10 | * Redistribution and use in source and binary forms, with or without |
| 11 | * modification, are permitted provided that the following conditions |
| 12 | * are met: |
| 13 | * 1. Redistributions of source code must retain the above copyright |
| 14 | * notice, this list of conditions and the following disclaimer. |
| 15 | * 2. Redistributions in binary form must reproduce the above copyright |
| 16 | * notice, this list of conditions and the following disclaimer in the |
| 17 | * documentation and/or other materials provided with the distribution. |
| 18 | * |
| 19 | * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS |
| 20 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
| 21 | * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| 22 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS |
| 23 | * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| 24 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| 25 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| 26 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| 27 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| 28 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| 29 | * POSSIBILITY OF SUCH DAMAGE. |
| 30 | */ |
| 31 | |
| 32 | #include <sys/cdefs.h> |
| 33 | __KERNEL_RCSID(0, "$NetBSD: kern_syscall.c,v 1.14 2015/11/30 23:34:47 pgoyette Exp $" ); |
| 34 | |
| 35 | #ifdef _KERNEL_OPT |
| 36 | #include "opt_modular.h" |
| 37 | #include "opt_syscall_debug.h" |
| 38 | #include "opt_ktrace.h" |
| 39 | #include "opt_ptrace.h" |
| 40 | #include "opt_dtrace.h" |
| 41 | #endif |
| 42 | |
| 43 | /* XXX To get syscall prototypes. */ |
| 44 | #define SYSVSHM |
| 45 | #define SYSVSEM |
| 46 | #define SYSVMSG |
| 47 | |
| 48 | #include <sys/param.h> |
| 49 | #include <sys/module.h> |
| 50 | #include <sys/sched.h> |
| 51 | #include <sys/syscall.h> |
| 52 | #include <sys/syscallargs.h> |
| 53 | #include <sys/syscallvar.h> |
| 54 | #include <sys/systm.h> |
| 55 | #include <sys/xcall.h> |
| 56 | #include <sys/ktrace.h> |
| 57 | #include <sys/ptrace.h> |
| 58 | |
| 59 | int |
| 60 | sys_nomodule(struct lwp *l, const void *v, register_t *retval) |
| 61 | { |
| 62 | #ifdef MODULAR |
| 63 | |
| 64 | const struct sysent *sy; |
| 65 | const struct emul *em; |
| 66 | const struct sc_autoload *auto_list; |
| 67 | u_int code; |
| 68 | |
| 69 | /* |
| 70 | * Restart the syscall if we interrupted a module unload that |
| 71 | * failed. Acquiring kernconfig_lock delays us until any unload |
| 72 | * has been completed or rolled back. |
| 73 | */ |
| 74 | kernconfig_lock(); |
| 75 | sy = l->l_sysent; |
| 76 | if (sy->sy_call != sys_nomodule) { |
| 77 | kernconfig_unlock(); |
| 78 | return ERESTART; |
| 79 | } |
| 80 | /* |
| 81 | * Try to autoload a module to satisfy the request. If it |
| 82 | * works, retry the request. |
| 83 | */ |
| 84 | em = l->l_proc->p_emul; |
| 85 | code = sy - em->e_sysent; |
| 86 | |
| 87 | if ((auto_list = em->e_sc_autoload) != NULL) |
| 88 | for (; auto_list->al_code > 0; auto_list++) { |
| 89 | if (auto_list->al_code != code) { |
| 90 | continue; |
| 91 | } |
| 92 | if (module_autoload(auto_list->al_module, |
| 93 | MODULE_CLASS_ANY) != 0 || |
| 94 | sy->sy_call == sys_nomodule) { |
| 95 | break; |
| 96 | } |
| 97 | kernconfig_unlock(); |
| 98 | return ERESTART; |
| 99 | } |
| 100 | kernconfig_unlock(); |
| 101 | #endif /* MODULAR */ |
| 102 | |
| 103 | return sys_nosys(l, v, retval); |
| 104 | } |
| 105 | |
| 106 | int |
| 107 | syscall_establish(const struct emul *em, const struct syscall_package *sp) |
| 108 | { |
| 109 | struct sysent *sy; |
| 110 | int i; |
| 111 | |
| 112 | KASSERT(kernconfig_is_held()); |
| 113 | |
| 114 | if (em == NULL) { |
| 115 | em = &emul_netbsd; |
| 116 | } |
| 117 | sy = em->e_sysent; |
| 118 | |
| 119 | /* |
| 120 | * Ensure that all preconditions are valid, since this is |
| 121 | * an all or nothing deal. Once a system call is entered, |
| 122 | * it can become busy and we could be unable to remove it |
| 123 | * on error. |
| 124 | */ |
| 125 | for (i = 0; sp[i].sp_call != NULL; i++) { |
| 126 | if (sy[sp[i].sp_code].sy_call != sys_nomodule) { |
| 127 | #ifdef DIAGNOSTIC |
| 128 | printf("syscall %d is busy\n" , sp[i].sp_code); |
| 129 | #endif |
| 130 | return EBUSY; |
| 131 | } |
| 132 | } |
| 133 | /* Everything looks good, patch them in. */ |
| 134 | for (i = 0; sp[i].sp_call != NULL; i++) { |
| 135 | sy[sp[i].sp_code].sy_call = sp[i].sp_call; |
| 136 | } |
| 137 | |
| 138 | return 0; |
| 139 | } |
| 140 | |
| 141 | int |
| 142 | syscall_disestablish(const struct emul *em, const struct syscall_package *sp) |
| 143 | { |
| 144 | struct sysent *sy; |
| 145 | uint64_t where; |
| 146 | lwp_t *l; |
| 147 | int i; |
| 148 | |
| 149 | KASSERT(kernconfig_is_held()); |
| 150 | |
| 151 | if (em == NULL) { |
| 152 | em = &emul_netbsd; |
| 153 | } |
| 154 | sy = em->e_sysent; |
| 155 | |
| 156 | /* |
| 157 | * First, patch the system calls to sys_nomodule to gate further |
| 158 | * activity. |
| 159 | */ |
| 160 | for (i = 0; sp[i].sp_call != NULL; i++) { |
| 161 | KASSERT(sy[sp[i].sp_code].sy_call == sp[i].sp_call); |
| 162 | sy[sp[i].sp_code].sy_call = sys_nomodule; |
| 163 | } |
| 164 | |
| 165 | /* |
| 166 | * Run a cross call to cycle through all CPUs. This does two |
| 167 | * things: lock activity provides a barrier and makes our update |
| 168 | * of sy_call visible to all CPUs, and upon return we can be sure |
| 169 | * that we see pertinent values of l_sysent posted by remote CPUs. |
| 170 | */ |
| 171 | where = xc_broadcast(0, (xcfunc_t)nullop, NULL, NULL); |
| 172 | xc_wait(where); |
| 173 | |
| 174 | /* |
| 175 | * Now it's safe to check l_sysent. Run through all LWPs and see |
| 176 | * if anyone is still using the system call. |
| 177 | */ |
| 178 | for (i = 0; sp[i].sp_call != NULL; i++) { |
| 179 | mutex_enter(proc_lock); |
| 180 | LIST_FOREACH(l, &alllwp, l_list) { |
| 181 | if (l->l_sysent == &sy[sp[i].sp_code]) { |
| 182 | break; |
| 183 | } |
| 184 | } |
| 185 | mutex_exit(proc_lock); |
| 186 | if (l == NULL) { |
| 187 | continue; |
| 188 | } |
| 189 | /* |
| 190 | * We lose: one or more calls are still in use. Put back |
| 191 | * the old entrypoints and act like nothing happened. |
| 192 | * When we drop kernconfig_lock, any system calls held in |
| 193 | * sys_nomodule() will be restarted. |
| 194 | */ |
| 195 | for (i = 0; sp[i].sp_call != NULL; i++) { |
| 196 | sy[sp[i].sp_code].sy_call = sp[i].sp_call; |
| 197 | } |
| 198 | return EBUSY; |
| 199 | } |
| 200 | |
| 201 | return 0; |
| 202 | } |
| 203 | |
| 204 | /* |
| 205 | * Return true if system call tracing is enabled for the specified process. |
| 206 | */ |
| 207 | bool |
| 208 | trace_is_enabled(struct proc *p) |
| 209 | { |
| 210 | #ifdef SYSCALL_DEBUG |
| 211 | return (true); |
| 212 | #endif |
| 213 | #ifdef KTRACE |
| 214 | if (ISSET(p->p_traceflag, (KTRFAC_SYSCALL | KTRFAC_SYSRET))) |
| 215 | return (true); |
| 216 | #endif |
| 217 | #ifdef PTRACE |
| 218 | if (ISSET(p->p_slflag, PSL_SYSCALL)) |
| 219 | return (true); |
| 220 | #endif |
| 221 | |
| 222 | return (false); |
| 223 | } |
| 224 | |
| 225 | /* |
| 226 | * Start trace of particular system call. If process is being traced, |
| 227 | * this routine is called by MD syscall dispatch code just before |
| 228 | * a system call is actually executed. |
| 229 | */ |
| 230 | int |
| 231 | trace_enter(register_t code, const struct sysent *sy, const void *args) |
| 232 | { |
| 233 | int error = 0; |
| 234 | |
| 235 | #ifdef KDTRACE_HOOKS |
| 236 | if (sy->sy_entry) { |
| 237 | struct emul *e = curlwp->l_proc->p_emul; |
| 238 | (*e->e_dtrace_syscall)(sy->sy_entry, code, sy, args, NULL, 0); |
| 239 | } |
| 240 | #endif |
| 241 | |
| 242 | #ifdef SYSCALL_DEBUG |
| 243 | scdebug_call(code, args); |
| 244 | #endif /* SYSCALL_DEBUG */ |
| 245 | |
| 246 | ktrsyscall(code, args, sy->sy_narg); |
| 247 | |
| 248 | #ifdef PTRACE |
| 249 | if ((curlwp->l_proc->p_slflag & (PSL_SYSCALL|PSL_TRACED)) == |
| 250 | (PSL_SYSCALL|PSL_TRACED)) { |
| 251 | process_stoptrace(); |
| 252 | if (curlwp->l_proc->p_slflag & PSL_SYSCALLEMU) { |
| 253 | /* tracer will emulate syscall for us */ |
| 254 | error = EJUSTRETURN; |
| 255 | } |
| 256 | } |
| 257 | #endif |
| 258 | return error; |
| 259 | } |
| 260 | |
| 261 | /* |
| 262 | * End trace of particular system call. If process is being traced, |
| 263 | * this routine is called by MD syscall dispatch code just after |
| 264 | * a system call finishes. |
| 265 | * MD caller guarantees the passed 'code' is within the supported |
| 266 | * system call number range for emulation the process runs under. |
| 267 | */ |
| 268 | void |
| 269 | trace_exit(register_t code, const struct sysent *sy, const void *args, |
| 270 | register_t rval[], int error) |
| 271 | { |
| 272 | #if defined(PTRACE) || defined(KDTRACE_HOOKS) |
| 273 | struct proc *p = curlwp->l_proc; |
| 274 | #endif |
| 275 | |
| 276 | #ifdef KDTRACE_HOOKS |
| 277 | if (sy->sy_return) { |
| 278 | (*p->p_emul->e_dtrace_syscall)(sy->sy_return, code, sy, args, |
| 279 | rval, error); |
| 280 | } |
| 281 | #endif |
| 282 | |
| 283 | #ifdef SYSCALL_DEBUG |
| 284 | scdebug_ret(code, error, rval); |
| 285 | #endif /* SYSCALL_DEBUG */ |
| 286 | |
| 287 | ktrsysret(code, error, rval); |
| 288 | |
| 289 | #ifdef PTRACE |
| 290 | if ((p->p_slflag & (PSL_SYSCALL|PSL_TRACED|PSL_SYSCALLEMU)) == |
| 291 | (PSL_SYSCALL|PSL_TRACED)) |
| 292 | process_stoptrace(); |
| 293 | CLR(p->p_slflag, PSL_SYSCALLEMU); |
| 294 | #endif |
| 295 | } |
| 296 | |