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 44 #include <sys/cdefs.h> 45 #include "opt_hwpmc_hooks.h" 46 47 #include <sys/param.h> 48 #include <sys/kernel.h> 49 #include <sys/limits.h> 50 #include <sys/lock.h> 51 #include <sys/msan.h> 52 #include <sys/mutex.h> 53 #include <sys/proc.h> 54 #include <sys/ktr.h> 55 #include <sys/resourcevar.h> 56 #include <sys/sched.h> 57 #include <sys/syscall.h> 58 #include <sys/syscallsubr.h> 59 #include <sys/sysent.h> 60 #include <sys/systm.h> 61 #include <sys/vmmeter.h> 62 63 #include <machine/cpu.h> 64 65 #ifdef VIMAGE 66 #include <net/vnet.h> 67 #endif 68 69 #ifdef HWPMC_HOOKS 70 #include <sys/pmckern.h> 71 #endif 72 73 #ifdef EPOCH_TRACE 74 #include <sys/epoch.h> 75 #endif 76 77 /* 78 * Define the code needed before returning to user mode, for trap and 79 * syscall. 80 */ 81 void 82 userret(struct thread *td, struct trapframe *frame) 83 { 84 struct proc *p = td->td_proc; 85 86 CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid, 87 td->td_name); 88 KASSERT((p->p_flag & P_WEXIT) == 0, 89 ("Exiting process returns to usermode")); 90 #ifdef DIAGNOSTIC 91 /* 92 * Check that we called signotify() enough. For 93 * multi-threaded processes, where signal distribution might 94 * change due to other threads changing sigmask, the check is 95 * racy and cannot be performed reliably. 96 * If current process is vfork child, indicated by P_PPWAIT, then 97 * issignal() ignores stops, so we block the check to avoid 98 * classifying pending signals. 99 */ 100 if (p->p_numthreads == 1) { 101 PROC_LOCK(p); 102 thread_lock(td); 103 if ((p->p_flag & P_PPWAIT) == 0 && 104 (td->td_pflags & TDP_SIGFASTBLOCK) == 0 && 105 SIGPENDING(td) && !td_ast_pending(td, TDA_AST) && 106 !td_ast_pending(td, TDA_SIG)) { 107 thread_unlock(td); 108 panic( 109 "failed to set signal flags for ast p %p " 110 "td %p td_ast %#x fl %#x", 111 p, td, td->td_ast, td->td_flags); 112 } 113 thread_unlock(td); 114 PROC_UNLOCK(p); 115 } 116 #endif 117 118 /* 119 * Charge system time if profiling. 120 */ 121 if (__predict_false(p->p_flag & P_PROFIL)) 122 addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio); 123 124 #ifdef HWPMC_HOOKS 125 if (PMC_THREAD_HAS_SAMPLES(td)) 126 PMC_CALL_HOOK(td, PMC_FN_THR_USERRET, NULL); 127 #endif 128 #ifdef TCPHPTS 129 /* 130 * @gallatin is adament that this needs to go here, I 131 * am not so sure. Running hpts is a lot like 132 * a lro_flush() that happens while a user process 133 * is running. But he may know best so I will go 134 * with his view of accounting. :-) 135 */ 136 tcp_run_hpts(); 137 #endif 138 /* 139 * Let the scheduler adjust our priority etc. 140 */ 141 sched_userret(td); 142 143 /* 144 * Check for misbehavior. 145 * 146 * In case there is a callchain tracing ongoing because of 147 * hwpmc(4), skip the scheduler pinning check. 148 * hwpmc(4) subsystem, infact, will collect callchain informations 149 * at ast() checkpoint, which is past userret(). 150 */ 151 WITNESS_WARN(WARN_PANIC, NULL, "userret: returning"); 152 KASSERT(td->td_critnest == 0, 153 ("userret: Returning in a critical section")); 154 KASSERT(td->td_locks == 0, 155 ("userret: Returning with %d locks held", td->td_locks)); 156 KASSERT(td->td_rw_rlocks == 0, 157 ("userret: Returning with %d rwlocks held in read mode", 158 td->td_rw_rlocks)); 159 KASSERT(td->td_sx_slocks == 0, 160 ("userret: Returning with %d sx locks held in shared mode", 161 td->td_sx_slocks)); 162 KASSERT(td->td_lk_slocks == 0, 163 ("userret: Returning with %d lockmanager locks held in shared mode", 164 td->td_lk_slocks)); 165 KASSERT((td->td_pflags & TDP_NOFAULTING) == 0, 166 ("userret: Returning with pagefaults disabled")); 167 if (__predict_false(!THREAD_CAN_SLEEP())) { 168 #ifdef EPOCH_TRACE 169 epoch_trace_list(curthread); 170 #endif 171 KASSERT(0, ("userret: Returning with sleep disabled")); 172 } 173 KASSERT(td->td_pinned == 0 || (td->td_pflags & TDP_CALLCHAIN) != 0, 174 ("userret: Returning with pinned thread")); 175 KASSERT(td->td_vp_reserved == NULL, 176 ("userret: Returning with preallocated vnode")); 177 KASSERT((td->td_flags & (TDF_SBDRY | TDF_SEINTR | TDF_SERESTART)) == 0, 178 ("userret: Returning with stop signals deferred")); 179 KASSERT(td->td_vslock_sz == 0, 180 ("userret: Returning with vslock-wired space")); 181 #ifdef VIMAGE 182 /* Unfortunately td_vnet_lpush needs VNET_DEBUG. */ 183 VNET_ASSERT(curvnet == NULL, 184 ("%s: Returning on td %p (pid %d, %s) with vnet %p set in %s", 185 __func__, td, p->p_pid, td->td_name, curvnet, 186 (td->td_vnet_lpush != NULL) ? td->td_vnet_lpush : "N/A")); 187 #endif 188 } 189 190 static void 191 ast_prep(struct thread *td, int tda __unused) 192 { 193 VM_CNT_INC(v_trap); 194 td->td_pticks = 0; 195 if (td->td_cowgen != atomic_load_int(&td->td_proc->p_cowgen)) 196 thread_cow_update(td); 197 198 } 199 200 struct ast_entry { 201 int ae_flags; 202 int ae_tdp; 203 void (*ae_f)(struct thread *td, int ast); 204 }; 205 206 _Static_assert(TDAI(TDA_MAX) <= UINT_MAX, "Too many ASTs"); 207 208 static struct ast_entry ast_entries[TDA_MAX] __read_mostly = { 209 [TDA_AST] = { .ae_f = ast_prep, .ae_flags = ASTR_UNCOND}, 210 }; 211 212 void 213 ast_register(int ast, int flags, int tdp, 214 void (*f)(struct thread *, int asts)) 215 { 216 struct ast_entry *ae; 217 218 MPASS(ast < TDA_MAX); 219 MPASS((flags & ASTR_TDP) == 0 || ((flags & ASTR_ASTF_REQUIRED) != 0 220 && __bitcount(tdp) == 1)); 221 ae = &ast_entries[ast]; 222 MPASS(ae->ae_f == NULL); 223 ae->ae_flags = flags; 224 ae->ae_tdp = tdp; 225 atomic_interrupt_fence(); 226 ae->ae_f = f; 227 } 228 229 /* 230 * XXXKIB Note that the deregistration of an AST handler does not 231 * drain threads possibly executing it, which affects unloadable 232 * modules. The issue is either handled by the subsystem using 233 * handlers, or simply ignored. Fixing the problem is considered not 234 * worth the overhead. 235 */ 236 void 237 ast_deregister(int ast) 238 { 239 struct ast_entry *ae; 240 241 MPASS(ast < TDA_MAX); 242 ae = &ast_entries[ast]; 243 MPASS(ae->ae_f != NULL); 244 ae->ae_f = NULL; 245 atomic_interrupt_fence(); 246 ae->ae_flags = 0; 247 ae->ae_tdp = 0; 248 } 249 250 void 251 ast_sched_locked(struct thread *td, int tda) 252 { 253 THREAD_LOCK_ASSERT(td, MA_OWNED); 254 MPASS(tda < TDA_MAX); 255 256 td->td_ast |= TDAI(tda); 257 } 258 259 void 260 ast_unsched_locked(struct thread *td, int tda) 261 { 262 THREAD_LOCK_ASSERT(td, MA_OWNED); 263 MPASS(tda < TDA_MAX); 264 265 td->td_ast &= ~TDAI(tda); 266 } 267 268 void 269 ast_sched(struct thread *td, int tda) 270 { 271 thread_lock(td); 272 ast_sched_locked(td, tda); 273 thread_unlock(td); 274 } 275 276 void 277 ast_sched_mask(struct thread *td, int ast) 278 { 279 thread_lock(td); 280 td->td_ast |= ast; 281 thread_unlock(td); 282 } 283 284 static bool 285 ast_handler_calc_tdp_run(struct thread *td, const struct ast_entry *ae) 286 { 287 return ((ae->ae_flags & ASTR_TDP) == 0 || 288 (td->td_pflags & ae->ae_tdp) != 0); 289 } 290 291 /* 292 * Process an asynchronous software trap. 293 */ 294 static void 295 ast_handler(struct thread *td, struct trapframe *framep, bool dtor) 296 { 297 struct ast_entry *ae; 298 void (*f)(struct thread *td, int asts); 299 int a, td_ast; 300 bool run; 301 302 if (framep != NULL) { 303 kmsan_mark(framep, sizeof(*framep), KMSAN_STATE_INITED); 304 td->td_frame = framep; 305 } 306 307 if (__predict_true(!dtor)) { 308 WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode"); 309 mtx_assert(&Giant, MA_NOTOWNED); 310 THREAD_LOCK_ASSERT(td, MA_NOTOWNED); 311 312 /* 313 * This updates the td_ast for the checks below in one 314 * atomic operation with turning off all scheduled AST's. 315 * If another AST is triggered while we are handling the 316 * AST's saved in td_ast, the td_ast is again non-zero and 317 * ast() will be called again. 318 */ 319 thread_lock(td); 320 td_ast = td->td_ast; 321 td->td_ast = 0; 322 thread_unlock(td); 323 } else { 324 /* 325 * The td thread's td_lock is not guaranteed to exist, 326 * the thread might be not initialized enough when it's 327 * destructor is called. It is safe to read and 328 * update td_ast without locking since the thread is 329 * not runnable or visible to other threads. 330 */ 331 td_ast = td->td_ast; 332 td->td_ast = 0; 333 } 334 335 CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, td->td_proc->p_pid, 336 td->td_proc->p_comm); 337 KASSERT(framep == NULL || TRAPF_USERMODE(framep), 338 ("ast in kernel mode")); 339 340 for (a = 0; a < nitems(ast_entries); a++) { 341 ae = &ast_entries[a]; 342 f = ae->ae_f; 343 if (f == NULL) 344 continue; 345 atomic_interrupt_fence(); 346 347 run = false; 348 if (__predict_false(framep == NULL)) { 349 if ((ae->ae_flags & ASTR_KCLEAR) != 0) 350 run = ast_handler_calc_tdp_run(td, ae); 351 } else { 352 if ((ae->ae_flags & ASTR_UNCOND) != 0) 353 run = true; 354 else if ((ae->ae_flags & ASTR_ASTF_REQUIRED) != 0 && 355 (td_ast & TDAI(a)) != 0) 356 run = ast_handler_calc_tdp_run(td, ae); 357 } 358 if (run) 359 f(td, td_ast); 360 } 361 } 362 363 void 364 ast(struct trapframe *framep) 365 { 366 struct thread *td; 367 368 td = curthread; 369 ast_handler(td, framep, false); 370 userret(td, framep); 371 } 372 373 void 374 ast_kclear(struct thread *td) 375 { 376 ast_handler(td, NULL, td != curthread); 377 } 378 379 const char * 380 syscallname(struct proc *p, u_int code) 381 { 382 static const char unknown[] = "unknown"; 383 struct sysentvec *sv; 384 385 sv = p->p_sysent; 386 if (sv->sv_syscallnames == NULL || code >= sv->sv_size) 387 return (unknown); 388 return (sv->sv_syscallnames[code]); 389 } 390