1 /*- 2 * SPDX-License-Identifier: BSD-4-Clause 3 * 4 * Copyright (C) 1994, David Greenman 5 * Copyright (c) 1990, 1993 6 * The Regents of the University of California. All rights reserved. 7 * Copyright (c) 2007, 2022 The FreeBSD Foundation 8 * 9 * This code is derived from software contributed to Berkeley by 10 * the University of Utah, and William Jolitz. 11 * 12 * Portions of this software were developed by A. Joseph Koshy under 13 * sponsorship from the FreeBSD Foundation and Google, Inc. 14 * 15 * Redistribution and use in source and binary forms, with or without 16 * modification, are permitted provided that the following conditions 17 * are met: 18 * 1. Redistributions of source code must retain the above copyright 19 * notice, this list of conditions and the following disclaimer. 20 * 2. Redistributions in binary form must reproduce the above copyright 21 * notice, this list of conditions and the following disclaimer in the 22 * documentation and/or other materials provided with the distribution. 23 * 3. All advertising materials mentioning features or use of this software 24 * must display the following acknowledgement: 25 * This product includes software developed by the University of 26 * California, Berkeley and its contributors. 27 * 4. Neither the name of the University nor the names of its contributors 28 * may be used to endorse or promote products derived from this software 29 * without specific prior written permission. 30 * 31 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 32 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 33 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 34 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 35 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 36 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 37 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 38 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 39 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 40 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 41 * SUCH DAMAGE. 42 * 43 * from: @(#)trap.c 7.4 (Berkeley) 5/13/91 44 */ 45 46 #include <sys/cdefs.h> 47 #include "opt_hwpmc_hooks.h" 48 49 #include <sys/param.h> 50 #include <sys/kernel.h> 51 #include <sys/limits.h> 52 #include <sys/lock.h> 53 #include <sys/msan.h> 54 #include <sys/mutex.h> 55 #include <sys/proc.h> 56 #include <sys/ktr.h> 57 #include <sys/resourcevar.h> 58 #include <sys/sched.h> 59 #include <sys/syscall.h> 60 #include <sys/syscallsubr.h> 61 #include <sys/sysent.h> 62 #include <sys/systm.h> 63 #include <sys/vmmeter.h> 64 65 #include <machine/cpu.h> 66 67 #ifdef VIMAGE 68 #include <net/vnet.h> 69 #endif 70 71 #ifdef HWPMC_HOOKS 72 #include <sys/pmckern.h> 73 #endif 74 75 #ifdef EPOCH_TRACE 76 #include <sys/epoch.h> 77 #endif 78 79 /* 80 * Define the code needed before returning to user mode, for trap and 81 * syscall. 82 */ 83 void 84 userret(struct thread *td, struct trapframe *frame) 85 { 86 struct proc *p = td->td_proc; 87 88 CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid, 89 td->td_name); 90 KASSERT((p->p_flag & P_WEXIT) == 0, 91 ("Exiting process returns to usermode")); 92 #ifdef DIAGNOSTIC 93 /* 94 * Check that we called signotify() enough. For 95 * multi-threaded processes, where signal distribution might 96 * change due to other threads changing sigmask, the check is 97 * racy and cannot be performed reliably. 98 * If current process is vfork child, indicated by P_PPWAIT, then 99 * issignal() ignores stops, so we block the check to avoid 100 * classifying pending signals. 101 */ 102 if (p->p_numthreads == 1) { 103 PROC_LOCK(p); 104 thread_lock(td); 105 if ((p->p_flag & P_PPWAIT) == 0 && 106 (td->td_pflags & TDP_SIGFASTBLOCK) == 0 && 107 SIGPENDING(td) && !td_ast_pending(td, TDA_AST) && 108 !td_ast_pending(td, TDA_SIG)) { 109 thread_unlock(td); 110 panic( 111 "failed to set signal flags for ast p %p " 112 "td %p td_ast %#x fl %#x", 113 p, td, td->td_ast, td->td_flags); 114 } 115 thread_unlock(td); 116 PROC_UNLOCK(p); 117 } 118 #endif 119 120 /* 121 * Charge system time if profiling. 122 */ 123 if (__predict_false(p->p_flag & P_PROFIL)) 124 addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio); 125 126 #ifdef HWPMC_HOOKS 127 if (PMC_THREAD_HAS_SAMPLES(td)) 128 PMC_CALL_HOOK(td, PMC_FN_THR_USERRET, NULL); 129 #endif 130 #ifdef TCPHPTS 131 /* 132 * @gallatin is adament that this needs to go here, I 133 * am not so sure. Running hpts is a lot like 134 * a lro_flush() that happens while a user process 135 * is running. But he may know best so I will go 136 * with his view of accounting. :-) 137 */ 138 tcp_run_hpts(); 139 #endif 140 /* 141 * Let the scheduler adjust our priority etc. 142 */ 143 sched_userret(td); 144 145 /* 146 * Check for misbehavior. 147 * 148 * In case there is a callchain tracing ongoing because of 149 * hwpmc(4), skip the scheduler pinning check. 150 * hwpmc(4) subsystem, infact, will collect callchain informations 151 * at ast() checkpoint, which is past userret(). 152 */ 153 WITNESS_WARN(WARN_PANIC, NULL, "userret: returning"); 154 KASSERT(td->td_critnest == 0, 155 ("userret: Returning in a critical section")); 156 KASSERT(td->td_locks == 0, 157 ("userret: Returning with %d locks held", td->td_locks)); 158 KASSERT(td->td_rw_rlocks == 0, 159 ("userret: Returning with %d rwlocks held in read mode", 160 td->td_rw_rlocks)); 161 KASSERT(td->td_sx_slocks == 0, 162 ("userret: Returning with %d sx locks held in shared mode", 163 td->td_sx_slocks)); 164 KASSERT(td->td_lk_slocks == 0, 165 ("userret: Returning with %d lockmanager locks held in shared mode", 166 td->td_lk_slocks)); 167 KASSERT((td->td_pflags & TDP_NOFAULTING) == 0, 168 ("userret: Returning with pagefaults disabled")); 169 if (__predict_false(!THREAD_CAN_SLEEP())) { 170 #ifdef EPOCH_TRACE 171 epoch_trace_list(curthread); 172 #endif 173 KASSERT(0, ("userret: Returning with sleep disabled")); 174 } 175 KASSERT(td->td_pinned == 0 || (td->td_pflags & TDP_CALLCHAIN) != 0, 176 ("userret: Returning with pinned thread")); 177 KASSERT(td->td_vp_reserved == NULL, 178 ("userret: Returning with preallocated vnode")); 179 KASSERT((td->td_flags & (TDF_SBDRY | TDF_SEINTR | TDF_SERESTART)) == 0, 180 ("userret: Returning with stop signals deferred")); 181 KASSERT(td->td_vslock_sz == 0, 182 ("userret: Returning with vslock-wired space")); 183 #ifdef VIMAGE 184 /* Unfortunately td_vnet_lpush needs VNET_DEBUG. */ 185 VNET_ASSERT(curvnet == NULL, 186 ("%s: Returning on td %p (pid %d, %s) with vnet %p set in %s", 187 __func__, td, p->p_pid, td->td_name, curvnet, 188 (td->td_vnet_lpush != NULL) ? td->td_vnet_lpush : "N/A")); 189 #endif 190 } 191 192 static void 193 ast_prep(struct thread *td, int tda __unused) 194 { 195 VM_CNT_INC(v_trap); 196 td->td_pticks = 0; 197 if (td->td_cowgen != atomic_load_int(&td->td_proc->p_cowgen)) 198 thread_cow_update(td); 199 200 } 201 202 struct ast_entry { 203 int ae_flags; 204 int ae_tdp; 205 void (*ae_f)(struct thread *td, int ast); 206 }; 207 208 _Static_assert(TDAI(TDA_MAX) <= UINT_MAX, "Too many ASTs"); 209 210 static struct ast_entry ast_entries[TDA_MAX] __read_mostly = { 211 [TDA_AST] = { .ae_f = ast_prep, .ae_flags = ASTR_UNCOND}, 212 }; 213 214 void 215 ast_register(int ast, int flags, int tdp, 216 void (*f)(struct thread *, int asts)) 217 { 218 struct ast_entry *ae; 219 220 MPASS(ast < TDA_MAX); 221 MPASS((flags & ASTR_TDP) == 0 || ((flags & ASTR_ASTF_REQUIRED) != 0 222 && __bitcount(tdp) == 1)); 223 ae = &ast_entries[ast]; 224 MPASS(ae->ae_f == NULL); 225 ae->ae_flags = flags; 226 ae->ae_tdp = tdp; 227 atomic_interrupt_fence(); 228 ae->ae_f = f; 229 } 230 231 /* 232 * XXXKIB Note that the deregistration of an AST handler does not 233 * drain threads possibly executing it, which affects unloadable 234 * modules. The issue is either handled by the subsystem using 235 * handlers, or simply ignored. Fixing the problem is considered not 236 * worth the overhead. 237 */ 238 void 239 ast_deregister(int ast) 240 { 241 struct ast_entry *ae; 242 243 MPASS(ast < TDA_MAX); 244 ae = &ast_entries[ast]; 245 MPASS(ae->ae_f != NULL); 246 ae->ae_f = NULL; 247 atomic_interrupt_fence(); 248 ae->ae_flags = 0; 249 ae->ae_tdp = 0; 250 } 251 252 void 253 ast_sched_locked(struct thread *td, int tda) 254 { 255 THREAD_LOCK_ASSERT(td, MA_OWNED); 256 MPASS(tda < TDA_MAX); 257 258 td->td_ast |= TDAI(tda); 259 } 260 261 void 262 ast_unsched_locked(struct thread *td, int tda) 263 { 264 THREAD_LOCK_ASSERT(td, MA_OWNED); 265 MPASS(tda < TDA_MAX); 266 267 td->td_ast &= ~TDAI(tda); 268 } 269 270 void 271 ast_sched(struct thread *td, int tda) 272 { 273 thread_lock(td); 274 ast_sched_locked(td, tda); 275 thread_unlock(td); 276 } 277 278 void 279 ast_sched_mask(struct thread *td, int ast) 280 { 281 thread_lock(td); 282 td->td_ast |= ast; 283 thread_unlock(td); 284 } 285 286 static bool 287 ast_handler_calc_tdp_run(struct thread *td, const struct ast_entry *ae) 288 { 289 return ((ae->ae_flags & ASTR_TDP) == 0 || 290 (td->td_pflags & ae->ae_tdp) != 0); 291 } 292 293 /* 294 * Process an asynchronous software trap. 295 */ 296 static void 297 ast_handler(struct thread *td, struct trapframe *framep, bool dtor) 298 { 299 struct ast_entry *ae; 300 void (*f)(struct thread *td, int asts); 301 int a, td_ast; 302 bool run; 303 304 if (framep != NULL) { 305 kmsan_mark(framep, sizeof(*framep), KMSAN_STATE_INITED); 306 td->td_frame = framep; 307 } 308 309 if (__predict_true(!dtor)) { 310 WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode"); 311 mtx_assert(&Giant, MA_NOTOWNED); 312 THREAD_LOCK_ASSERT(td, MA_NOTOWNED); 313 314 /* 315 * This updates the td_ast for the checks below in one 316 * atomic operation with turning off all scheduled AST's. 317 * If another AST is triggered while we are handling the 318 * AST's saved in td_ast, the td_ast is again non-zero and 319 * ast() will be called again. 320 */ 321 thread_lock(td); 322 td_ast = td->td_ast; 323 td->td_ast = 0; 324 thread_unlock(td); 325 } else { 326 /* 327 * The td thread's td_lock is not guaranteed to exist, 328 * the thread might be not initialized enough when it's 329 * destructor is called. It is safe to read and 330 * update td_ast without locking since the thread is 331 * not runnable or visible to other threads. 332 */ 333 td_ast = td->td_ast; 334 td->td_ast = 0; 335 } 336 337 CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, td->td_proc->p_pid, 338 td->td_proc->p_comm); 339 KASSERT(framep == NULL || TRAPF_USERMODE(framep), 340 ("ast in kernel mode")); 341 342 for (a = 0; a < nitems(ast_entries); a++) { 343 ae = &ast_entries[a]; 344 f = ae->ae_f; 345 if (f == NULL) 346 continue; 347 atomic_interrupt_fence(); 348 349 run = false; 350 if (__predict_false(framep == NULL)) { 351 if ((ae->ae_flags & ASTR_KCLEAR) != 0) 352 run = ast_handler_calc_tdp_run(td, ae); 353 } else { 354 if ((ae->ae_flags & ASTR_UNCOND) != 0) 355 run = true; 356 else if ((ae->ae_flags & ASTR_ASTF_REQUIRED) != 0 && 357 (td_ast & TDAI(a)) != 0) 358 run = ast_handler_calc_tdp_run(td, ae); 359 } 360 if (run) 361 f(td, td_ast); 362 } 363 } 364 365 void 366 ast(struct trapframe *framep) 367 { 368 struct thread *td; 369 370 td = curthread; 371 ast_handler(td, framep, false); 372 userret(td, framep); 373 } 374 375 void 376 ast_kclear(struct thread *td) 377 { 378 ast_handler(td, NULL, td != curthread); 379 } 380 381 const char * 382 syscallname(struct proc *p, u_int code) 383 { 384 static const char unknown[] = "unknown"; 385 struct sysentvec *sv; 386 387 sv = p->p_sysent; 388 if (sv->sv_syscallnames == NULL || code >= sv->sv_size) 389 return (unknown); 390 return (sv->sv_syscallnames[code]); 391 } 392