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 /* 129 * Let the scheduler adjust our priority etc. 130 */ 131 sched_userret(td); 132 133 /* 134 * Check for misbehavior. 135 * 136 * In case there is a callchain tracing ongoing because of 137 * hwpmc(4), skip the scheduler pinning check. 138 * hwpmc(4) subsystem, infact, will collect callchain informations 139 * at ast() checkpoint, which is past userret(). 140 */ 141 WITNESS_WARN(WARN_PANIC, NULL, "userret: returning"); 142 KASSERT(td->td_critnest == 0, 143 ("userret: Returning in a critical section")); 144 KASSERT(td->td_locks == 0, 145 ("userret: Returning with %d locks held", td->td_locks)); 146 KASSERT(td->td_rw_rlocks == 0, 147 ("userret: Returning with %d rwlocks held in read mode", 148 td->td_rw_rlocks)); 149 KASSERT(td->td_sx_slocks == 0, 150 ("userret: Returning with %d sx locks held in shared mode", 151 td->td_sx_slocks)); 152 KASSERT(td->td_lk_slocks == 0, 153 ("userret: Returning with %d lockmanager locks held in shared mode", 154 td->td_lk_slocks)); 155 KASSERT((td->td_pflags & TDP_NOFAULTING) == 0, 156 ("userret: Returning with pagefaults disabled")); 157 if (__predict_false(!THREAD_CAN_SLEEP())) { 158 #ifdef EPOCH_TRACE 159 epoch_trace_list(curthread); 160 #endif 161 KASSERT(0, ("userret: Returning with sleep disabled")); 162 } 163 KASSERT(td->td_pinned == 0 || (td->td_pflags & TDP_CALLCHAIN) != 0, 164 ("userret: Returning with pinned thread")); 165 KASSERT(td->td_vp_reserved == NULL, 166 ("userret: Returning with preallocated vnode")); 167 KASSERT((td->td_flags & (TDF_SBDRY | TDF_SEINTR | TDF_SERESTART)) == 0, 168 ("userret: Returning with stop signals deferred")); 169 KASSERT(td->td_vslock_sz == 0, 170 ("userret: Returning with vslock-wired space")); 171 #ifdef VIMAGE 172 /* Unfortunately td_vnet_lpush needs VNET_DEBUG. */ 173 VNET_ASSERT(curvnet == NULL, 174 ("%s: Returning on td %p (pid %d, %s) with vnet %p set in %s", 175 __func__, td, p->p_pid, td->td_name, curvnet, 176 (td->td_vnet_lpush != NULL) ? td->td_vnet_lpush : "N/A")); 177 #endif 178 } 179 180 static void 181 ast_prep(struct thread *td, int tda __unused) 182 { 183 VM_CNT_INC(v_trap); 184 td->td_pticks = 0; 185 if (td->td_cowgen != atomic_load_int(&td->td_proc->p_cowgen)) 186 thread_cow_update(td); 187 188 } 189 190 struct ast_entry { 191 int ae_flags; 192 int ae_tdp; 193 void (*ae_f)(struct thread *td, int ast); 194 }; 195 196 _Static_assert(TDAI(TDA_MAX) <= UINT_MAX, "Too many ASTs"); 197 198 static struct ast_entry ast_entries[TDA_MAX] __read_mostly = { 199 [TDA_AST] = { .ae_f = ast_prep, .ae_flags = ASTR_UNCOND}, 200 }; 201 202 void 203 ast_register(int ast, int flags, int tdp, 204 void (*f)(struct thread *, int asts)) 205 { 206 struct ast_entry *ae; 207 208 MPASS(ast < TDA_MAX); 209 MPASS((flags & ASTR_TDP) == 0 || ((flags & ASTR_ASTF_REQUIRED) != 0 210 && __bitcount(tdp) == 1)); 211 ae = &ast_entries[ast]; 212 MPASS(ae->ae_f == NULL); 213 ae->ae_flags = flags; 214 ae->ae_tdp = tdp; 215 atomic_interrupt_fence(); 216 ae->ae_f = f; 217 } 218 219 /* 220 * XXXKIB Note that the deregistration of an AST handler does not 221 * drain threads possibly executing it, which affects unloadable 222 * modules. The issue is either handled by the subsystem using 223 * handlers, or simply ignored. Fixing the problem is considered not 224 * worth the overhead. 225 */ 226 void 227 ast_deregister(int ast) 228 { 229 struct ast_entry *ae; 230 231 MPASS(ast < TDA_MAX); 232 ae = &ast_entries[ast]; 233 MPASS(ae->ae_f != NULL); 234 ae->ae_f = NULL; 235 atomic_interrupt_fence(); 236 ae->ae_flags = 0; 237 ae->ae_tdp = 0; 238 } 239 240 void 241 ast_sched_locked(struct thread *td, int tda) 242 { 243 THREAD_LOCK_ASSERT(td, MA_OWNED); 244 MPASS(tda < TDA_MAX); 245 246 td->td_ast |= TDAI(tda); 247 } 248 249 void 250 ast_unsched_locked(struct thread *td, int tda) 251 { 252 THREAD_LOCK_ASSERT(td, MA_OWNED); 253 MPASS(tda < TDA_MAX); 254 255 td->td_ast &= ~TDAI(tda); 256 } 257 258 void 259 ast_sched(struct thread *td, int tda) 260 { 261 thread_lock(td); 262 ast_sched_locked(td, tda); 263 thread_unlock(td); 264 } 265 266 void 267 ast_sched_mask(struct thread *td, int ast) 268 { 269 thread_lock(td); 270 td->td_ast |= ast; 271 thread_unlock(td); 272 } 273 274 static bool 275 ast_handler_calc_tdp_run(struct thread *td, const struct ast_entry *ae) 276 { 277 return ((ae->ae_flags & ASTR_TDP) == 0 || 278 (td->td_pflags & ae->ae_tdp) != 0); 279 } 280 281 /* 282 * Process an asynchronous software trap. 283 */ 284 static void 285 ast_handler(struct thread *td, struct trapframe *framep, bool dtor) 286 { 287 struct ast_entry *ae; 288 void (*f)(struct thread *td, int asts); 289 int a, td_ast; 290 bool run; 291 292 if (framep != NULL) { 293 kmsan_mark(framep, sizeof(*framep), KMSAN_STATE_INITED); 294 td->td_frame = framep; 295 } 296 297 if (__predict_true(!dtor)) { 298 WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode"); 299 mtx_assert(&Giant, MA_NOTOWNED); 300 THREAD_LOCK_ASSERT(td, MA_NOTOWNED); 301 302 /* 303 * This updates the td_ast for the checks below in one 304 * atomic operation with turning off all scheduled AST's. 305 * If another AST is triggered while we are handling the 306 * AST's saved in td_ast, the td_ast is again non-zero and 307 * ast() will be called again. 308 */ 309 thread_lock(td); 310 td_ast = td->td_ast; 311 td->td_ast = 0; 312 thread_unlock(td); 313 } else { 314 /* 315 * The td thread's td_lock is not guaranteed to exist, 316 * the thread might be not initialized enough when it's 317 * destructor is called. It is safe to read and 318 * update td_ast without locking since the thread is 319 * not runnable or visible to other threads. 320 */ 321 td_ast = td->td_ast; 322 td->td_ast = 0; 323 } 324 325 CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, 326 td->td_proc == NULL ? -1 : td->td_proc->p_pid, 327 td->td_proc == NULL ? "" : td->td_proc->p_comm); 328 KASSERT(framep == NULL || TRAPF_USERMODE(framep), 329 ("ast in kernel mode")); 330 331 for (a = 0; a < nitems(ast_entries); a++) { 332 ae = &ast_entries[a]; 333 f = ae->ae_f; 334 if (f == NULL) 335 continue; 336 atomic_interrupt_fence(); 337 338 run = false; 339 if (__predict_false(framep == NULL)) { 340 if ((ae->ae_flags & ASTR_KCLEAR) != 0) 341 run = ast_handler_calc_tdp_run(td, ae); 342 } else { 343 if ((ae->ae_flags & ASTR_UNCOND) != 0) 344 run = true; 345 else if ((ae->ae_flags & ASTR_ASTF_REQUIRED) != 0 && 346 (td_ast & TDAI(a)) != 0) 347 run = ast_handler_calc_tdp_run(td, ae); 348 } 349 if (run) 350 f(td, td_ast); 351 } 352 } 353 354 void 355 ast(struct trapframe *framep) 356 { 357 struct thread *td; 358 359 td = curthread; 360 ast_handler(td, framep, false); 361 userret(td, framep); 362 } 363 364 void 365 ast_kclear(struct thread *td) 366 { 367 ast_handler(td, NULL, td != curthread); 368 } 369 370 const char * 371 syscallname(struct proc *p, u_int code) 372 { 373 static const char unknown[] = "unknown"; 374 struct sysentvec *sv; 375 376 sv = p->p_sysent; 377 if (sv->sv_syscallnames == NULL || code >= sv->sv_size) 378 return (unknown); 379 return (sv->sv_syscallnames[code]); 380 } 381