github.com/lzhfromustc/gofuzz@v0.0.0-20211116160056-151b3108bbd1/runtime/runtime2.go (about) 1 // Copyright 2009 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 package runtime 6 7 import ( 8 "internal/cpu" 9 "runtime/internal/atomic" 10 "runtime/internal/sys" 11 "unsafe" 12 ) 13 14 // defined constants 15 const ( 16 // G status 17 // 18 // Beyond indicating the general state of a G, the G status 19 // acts like a lock on the goroutine's stack (and hence its 20 // ability to execute user code). 21 // 22 // If you add to this list, add to the list 23 // of "okay during garbage collection" status 24 // in mgcmark.go too. 25 // 26 // TODO(austin): The _Gscan bit could be much lighter-weight. 27 // For example, we could choose not to run _Gscanrunnable 28 // goroutines found in the run queue, rather than CAS-looping 29 // until they become _Grunnable. And transitions like 30 // _Gscanwaiting -> _Gscanrunnable are actually okay because 31 // they don't affect stack ownership. 32 33 // _Gidle means this goroutine was just allocated and has not 34 // yet been initialized. 35 _Gidle = iota // 0 36 37 // _Grunnable means this goroutine is on a run queue. It is 38 // not currently executing user code. The stack is not owned. 39 _Grunnable // 1 40 41 // _Grunning means this goroutine may execute user code. The 42 // stack is owned by this goroutine. It is not on a run queue. 43 // It is assigned an M and a P (g.m and g.m.p are valid). 44 _Grunning // 2 45 46 // _Gsyscall means this goroutine is executing a system call. 47 // It is not executing user code. The stack is owned by this 48 // goroutine. It is not on a run queue. It is assigned an M. 49 _Gsyscall // 3 50 51 // _Gwaiting means this goroutine is blocked in the runtime. 52 // It is not executing user code. It is not on a run queue, 53 // but should be recorded somewhere (e.g., a channel wait 54 // queue) so it can be ready()d when necessary. The stack is 55 // not owned *except* that a channel operation may read or 56 // write parts of the stack under the appropriate channel 57 // lock. Otherwise, it is not safe to access the stack after a 58 // goroutine enters _Gwaiting (e.g., it may get moved). 59 _Gwaiting // 4 60 61 // _Gmoribund_unused is currently unused, but hardcoded in gdb 62 // scripts. 63 _Gmoribund_unused // 5 64 65 // _Gdead means this goroutine is currently unused. It may be 66 // just exited, on a free list, or just being initialized. It 67 // is not executing user code. It may or may not have a stack 68 // allocated. The G and its stack (if any) are owned by the M 69 // that is exiting the G or that obtained the G from the free 70 // list. 71 _Gdead // 6 72 73 // _Genqueue_unused is currently unused. 74 _Genqueue_unused // 7 75 76 // _Gcopystack means this goroutine's stack is being moved. It 77 // is not executing user code and is not on a run queue. The 78 // stack is owned by the goroutine that put it in _Gcopystack. 79 _Gcopystack // 8 80 81 // _Gpreempted means this goroutine stopped itself for a 82 // suspendG preemption. It is like _Gwaiting, but nothing is 83 // yet responsible for ready()ing it. Some suspendG must CAS 84 // the status to _Gwaiting to take responsibility for 85 // ready()ing this G. 86 _Gpreempted // 9 87 88 // _Gscan combined with one of the above states other than 89 // _Grunning indicates that GC is scanning the stack. The 90 // goroutine is not executing user code and the stack is owned 91 // by the goroutine that set the _Gscan bit. 92 // 93 // _Gscanrunning is different: it is used to briefly block 94 // state transitions while GC signals the G to scan its own 95 // stack. This is otherwise like _Grunning. 96 // 97 // atomicstatus&~Gscan gives the state the goroutine will 98 // return to when the scan completes. 99 _Gscan = 0x1000 100 _Gscanrunnable = _Gscan + _Grunnable // 0x1001 101 _Gscanrunning = _Gscan + _Grunning // 0x1002 102 _Gscansyscall = _Gscan + _Gsyscall // 0x1003 103 _Gscanwaiting = _Gscan + _Gwaiting // 0x1004 104 _Gscanpreempted = _Gscan + _Gpreempted // 0x1009 105 ) 106 107 const ( 108 // P status 109 110 // _Pidle means a P is not being used to run user code or the 111 // scheduler. Typically, it's on the idle P list and available 112 // to the scheduler, but it may just be transitioning between 113 // other states. 114 // 115 // The P is owned by the idle list or by whatever is 116 // transitioning its state. Its run queue is empty. 117 _Pidle = iota 118 119 // _Prunning means a P is owned by an M and is being used to 120 // run user code or the scheduler. Only the M that owns this P 121 // is allowed to change the P's status from _Prunning. The M 122 // may transition the P to _Pidle (if it has no more work to 123 // do), _Psyscall (when entering a syscall), or _Pgcstop (to 124 // halt for the GC). The M may also hand ownership of the P 125 // off directly to another M (e.g., to schedule a locked G). 126 _Prunning 127 128 // _Psyscall means a P is not running user code. It has 129 // affinity to an M in a syscall but is not owned by it and 130 // may be stolen by another M. This is similar to _Pidle but 131 // uses lightweight transitions and maintains M affinity. 132 // 133 // Leaving _Psyscall must be done with a CAS, either to steal 134 // or retake the P. Note that there's an ABA hazard: even if 135 // an M successfully CASes its original P back to _Prunning 136 // after a syscall, it must understand the P may have been 137 // used by another M in the interim. 138 _Psyscall 139 140 // _Pgcstop means a P is halted for STW and owned by the M 141 // that stopped the world. The M that stopped the world 142 // continues to use its P, even in _Pgcstop. Transitioning 143 // from _Prunning to _Pgcstop causes an M to release its P and 144 // park. 145 // 146 // The P retains its run queue and startTheWorld will restart 147 // the scheduler on Ps with non-empty run queues. 148 _Pgcstop 149 150 // _Pdead means a P is no longer used (GOMAXPROCS shrank). We 151 // reuse Ps if GOMAXPROCS increases. A dead P is mostly 152 // stripped of its resources, though a few things remain 153 // (e.g., trace buffers). 154 _Pdead 155 ) 156 157 // Mutual exclusion locks. In the uncontended case, 158 // as fast as spin locks (just a few user-level instructions), 159 // but on the contention path they sleep in the kernel. 160 // A zeroed Mutex is unlocked (no need to initialize each lock). 161 // Initialization is helpful for static lock ranking, but not required. 162 type mutex struct { 163 // Empty struct if lock ranking is disabled, otherwise includes the lock rank 164 lockRankStruct 165 // Futex-based impl treats it as uint32 key, 166 // while sema-based impl as M* waitm. 167 // Used to be a union, but unions break precise GC. 168 key uintptr 169 } 170 171 // sleep and wakeup on one-time events. 172 // before any calls to notesleep or notewakeup, 173 // must call noteclear to initialize the Note. 174 // then, exactly one thread can call notesleep 175 // and exactly one thread can call notewakeup (once). 176 // once notewakeup has been called, the notesleep 177 // will return. future notesleep will return immediately. 178 // subsequent noteclear must be called only after 179 // previous notesleep has returned, e.g. it's disallowed 180 // to call noteclear straight after notewakeup. 181 // 182 // notetsleep is like notesleep but wakes up after 183 // a given number of nanoseconds even if the event 184 // has not yet happened. if a goroutine uses notetsleep to 185 // wake up early, it must wait to call noteclear until it 186 // can be sure that no other goroutine is calling 187 // notewakeup. 188 // 189 // notesleep/notetsleep are generally called on g0, 190 // notetsleepg is similar to notetsleep but is called on user g. 191 type note struct { 192 // Futex-based impl treats it as uint32 key, 193 // while sema-based impl as M* waitm. 194 // Used to be a union, but unions break precise GC. 195 key uintptr 196 } 197 198 type funcval struct { 199 fn uintptr 200 // variable-size, fn-specific data here 201 } 202 203 type iface struct { 204 tab *itab 205 data unsafe.Pointer 206 } 207 208 type eface struct { 209 _type *_type 210 data unsafe.Pointer 211 } 212 213 func efaceOf(ep *interface{}) *eface { 214 return (*eface)(unsafe.Pointer(ep)) 215 } 216 217 // The guintptr, muintptr, and puintptr are all used to bypass write barriers. 218 // It is particularly important to avoid write barriers when the current P has 219 // been released, because the GC thinks the world is stopped, and an 220 // unexpected write barrier would not be synchronized with the GC, 221 // which can lead to a half-executed write barrier that has marked the object 222 // but not queued it. If the GC skips the object and completes before the 223 // queuing can occur, it will incorrectly free the object. 224 // 225 // We tried using special assignment functions invoked only when not 226 // holding a running P, but then some updates to a particular memory 227 // word went through write barriers and some did not. This breaks the 228 // write barrier shadow checking mode, and it is also scary: better to have 229 // a word that is completely ignored by the GC than to have one for which 230 // only a few updates are ignored. 231 // 232 // Gs and Ps are always reachable via true pointers in the 233 // allgs and allp lists or (during allocation before they reach those lists) 234 // from stack variables. 235 // 236 // Ms are always reachable via true pointers either from allm or 237 // freem. Unlike Gs and Ps we do free Ms, so it's important that 238 // nothing ever hold an muintptr across a safe point. 239 240 // A guintptr holds a goroutine pointer, but typed as a uintptr 241 // to bypass write barriers. It is used in the Gobuf goroutine state 242 // and in scheduling lists that are manipulated without a P. 243 // 244 // The Gobuf.g goroutine pointer is almost always updated by assembly code. 245 // In one of the few places it is updated by Go code - func save - it must be 246 // treated as a uintptr to avoid a write barrier being emitted at a bad time. 247 // Instead of figuring out how to emit the write barriers missing in the 248 // assembly manipulation, we change the type of the field to uintptr, 249 // so that it does not require write barriers at all. 250 // 251 // Goroutine structs are published in the allg list and never freed. 252 // That will keep the goroutine structs from being collected. 253 // There is never a time that Gobuf.g's contain the only references 254 // to a goroutine: the publishing of the goroutine in allg comes first. 255 // Goroutine pointers are also kept in non-GC-visible places like TLS, 256 // so I can't see them ever moving. If we did want to start moving data 257 // in the GC, we'd need to allocate the goroutine structs from an 258 // alternate arena. Using guintptr doesn't make that problem any worse. 259 type guintptr uintptr 260 261 //go:nosplit 262 func (gp guintptr) ptr() *g { return (*g)(unsafe.Pointer(gp)) } 263 264 //go:nosplit 265 func (gp *guintptr) set(g *g) { *gp = guintptr(unsafe.Pointer(g)) } 266 267 //go:nosplit 268 func (gp *guintptr) cas(old, new guintptr) bool { 269 return atomic.Casuintptr((*uintptr)(unsafe.Pointer(gp)), uintptr(old), uintptr(new)) 270 } 271 272 // setGNoWB performs *gp = new without a write barrier. 273 // For times when it's impractical to use a guintptr. 274 //go:nosplit 275 //go:nowritebarrier 276 func setGNoWB(gp **g, new *g) { 277 (*guintptr)(unsafe.Pointer(gp)).set(new) 278 } 279 280 type puintptr uintptr 281 282 //go:nosplit 283 func (pp puintptr) ptr() *p { return (*p)(unsafe.Pointer(pp)) } 284 285 //go:nosplit 286 func (pp *puintptr) set(p *p) { *pp = puintptr(unsafe.Pointer(p)) } 287 288 // muintptr is a *m that is not tracked by the garbage collector. 289 // 290 // Because we do free Ms, there are some additional constrains on 291 // muintptrs: 292 // 293 // 1. Never hold an muintptr locally across a safe point. 294 // 295 // 2. Any muintptr in the heap must be owned by the M itself so it can 296 // ensure it is not in use when the last true *m is released. 297 type muintptr uintptr 298 299 //go:nosplit 300 func (mp muintptr) ptr() *m { return (*m)(unsafe.Pointer(mp)) } 301 302 //go:nosplit 303 func (mp *muintptr) set(m *m) { *mp = muintptr(unsafe.Pointer(m)) } 304 305 // setMNoWB performs *mp = new without a write barrier. 306 // For times when it's impractical to use an muintptr. 307 //go:nosplit 308 //go:nowritebarrier 309 func setMNoWB(mp **m, new *m) { 310 (*muintptr)(unsafe.Pointer(mp)).set(new) 311 } 312 313 type gobuf struct { 314 // The offsets of sp, pc, and g are known to (hard-coded in) libmach. 315 // 316 // ctxt is unusual with respect to GC: it may be a 317 // heap-allocated funcval, so GC needs to track it, but it 318 // needs to be set and cleared from assembly, where it's 319 // difficult to have write barriers. However, ctxt is really a 320 // saved, live register, and we only ever exchange it between 321 // the real register and the gobuf. Hence, we treat it as a 322 // root during stack scanning, which means assembly that saves 323 // and restores it doesn't need write barriers. It's still 324 // typed as a pointer so that any other writes from Go get 325 // write barriers. 326 sp uintptr 327 pc uintptr 328 g guintptr 329 ctxt unsafe.Pointer 330 ret sys.Uintreg 331 lr uintptr 332 bp uintptr // for framepointer-enabled architectures 333 } 334 335 // sudog represents a g in a wait list, such as for sending/receiving 336 // on a channel. 337 // 338 // sudog is necessary because the g ↔ synchronization object relation 339 // is many-to-many. A g can be on many wait lists, so there may be 340 // many sudogs for one g; and many gs may be waiting on the same 341 // synchronization object, so there may be many sudogs for one object. 342 // 343 // sudogs are allocated from a special pool. Use acquireSudog and 344 // releaseSudog to allocate and free them. 345 type sudog struct { 346 // The following fields are protected by the hchan.lock of the 347 // channel this sudog is blocking on. shrinkstack depends on 348 // this for sudogs involved in channel ops. 349 350 g *g 351 352 next *sudog 353 prev *sudog 354 elem unsafe.Pointer // data element (may point to stack) 355 356 // The following fields are never accessed concurrently. 357 // For channels, waitlink is only accessed by g. 358 // For semaphores, all fields (including the ones above) 359 // are only accessed when holding a semaRoot lock. 360 361 acquiretime int64 362 releasetime int64 363 ticket uint32 364 365 // isSelect indicates g is participating in a select, so 366 // g.selectDone must be CAS'd to win the wake-up race. 367 isSelect bool 368 369 // success indicates whether communication over channel c 370 // succeeded. It is true if the goroutine was awoken because a 371 // value was delivered over channel c, and false if awoken 372 // because c was closed. 373 success bool 374 375 parent *sudog // semaRoot binary tree 376 waitlink *sudog // g.waiting list or semaRoot 377 waittail *sudog // semaRoot 378 c *hchan // channel 379 } 380 381 type libcall struct { 382 fn uintptr 383 n uintptr // number of parameters 384 args uintptr // parameters 385 r1 uintptr // return values 386 r2 uintptr 387 err uintptr // error number 388 } 389 390 // Stack describes a Go execution stack. 391 // The bounds of the stack are exactly [lo, hi), 392 // with no implicit data structures on either side. 393 type stack struct { 394 lo uintptr 395 hi uintptr 396 } 397 398 // heldLockInfo gives info on a held lock and the rank of that lock 399 type heldLockInfo struct { 400 lockAddr uintptr 401 rank lockRank 402 } 403 404 type g struct { 405 // Stack parameters. 406 // stack describes the actual stack memory: [stack.lo, stack.hi). 407 // stackguard0 is the stack pointer compared in the Go stack growth prologue. 408 // It is stack.lo+StackGuard normally, but can be StackPreempt to trigger a preemption. 409 // stackguard1 is the stack pointer compared in the C stack growth prologue. 410 // It is stack.lo+StackGuard on g0 and gsignal stacks. 411 // It is ~0 on other goroutine stacks, to trigger a call to morestackc (and crash). 412 stack stack // offset known to runtime/cgo 413 stackguard0 uintptr // offset known to liblink 414 stackguard1 uintptr // offset known to liblink 415 416 _panic *_panic // innermost panic - offset known to liblink 417 _defer *_defer // innermost defer 418 m *m // current m; offset known to arm liblink 419 sched gobuf 420 syscallsp uintptr // if status==Gsyscall, syscallsp = sched.sp to use during gc 421 syscallpc uintptr // if status==Gsyscall, syscallpc = sched.pc to use during gc 422 stktopsp uintptr // expected sp at top of stack, to check in traceback 423 param unsafe.Pointer // passed parameter on wakeup 424 atomicstatus uint32 425 stackLock uint32 // sigprof/scang lock; TODO: fold in to atomicstatus 426 goid int64 427 schedlink guintptr 428 waitsince int64 // approx time when the g become blocked 429 waitreason waitReason // if status==Gwaiting 430 431 preempt bool // preemption signal, duplicates stackguard0 = stackpreempt 432 preemptStop bool // transition to _Gpreempted on preemption; otherwise, just deschedule 433 preemptShrink bool // shrink stack at synchronous safe point 434 435 // asyncSafePoint is set if g is stopped at an asynchronous 436 // safe point. This means there are frames on the stack 437 // without precise pointer information. 438 asyncSafePoint bool 439 440 paniconfault bool // panic (instead of crash) on unexpected fault address 441 gcscandone bool // g has scanned stack; protected by _Gscan bit in status 442 throwsplit bool // must not split stack 443 // activeStackChans indicates that there are unlocked channels 444 // pointing into this goroutine's stack. If true, stack 445 // copying needs to acquire channel locks to protect these 446 // areas of the stack. 447 activeStackChans bool 448 // parkingOnChan indicates that the goroutine is about to 449 // park on a chansend or chanrecv. Used to signal an unsafe point 450 // for stack shrinking. It's a boolean value, but is updated atomically. 451 parkingOnChan uint8 452 453 raceignore int8 // ignore race detection events 454 sysblocktraced bool // StartTrace has emitted EvGoInSyscall about this goroutine 455 sysexitticks int64 // cputicks when syscall has returned (for tracing) 456 traceseq uint64 // trace event sequencer 457 tracelastp puintptr // last P emitted an event for this goroutine 458 lockedm muintptr 459 sig uint32 460 writebuf []byte 461 sigcode0 uintptr 462 sigcode1 uintptr 463 sigpc uintptr 464 gopc uintptr // pc of go statement that created this goroutine 465 ancestors *[]ancestorInfo // ancestor information goroutine(s) that created this goroutine (only used if debug.tracebackancestors) 466 startpc uintptr // pc of goroutine function 467 racectx uintptr 468 waiting *sudog // sudog structures this g is waiting on (that have a valid elem ptr); in lock order 469 cgoCtxt []uintptr // cgo traceback context 470 labels unsafe.Pointer // profiler labels 471 timer *timer // cached timer for time.Sleep 472 selectDone uint32 // are we participating in a select and did someone win the race? 473 474 // Per-G GC state 475 476 // gcAssistBytes is this G's GC assist credit in terms of 477 // bytes allocated. If this is positive, then the G has credit 478 // to allocate gcAssistBytes bytes without assisting. If this 479 // is negative, then the G must correct this by performing 480 // scan work. We track this in bytes to make it fast to update 481 // and check for debt in the malloc hot path. The assist ratio 482 // determines how this corresponds to scan work debt. 483 gcAssistBytes int64 484 485 ///MYCODE 486 goInfo *GoInfo 487 lastPrimInfo PrimInfo 488 489 ///MYCODE 490 lastMySwitchLineNum string // Our inserted switch calls a function in gooracle, which records the line number of 491 // the original select corresponding to this switch. This variables records this line number so myselect.go can use it 492 lastMySwitchOriSelectNumCase int 493 lastMySwitchChoice int 494 strChOpType string // A local recording for the type of channel operation executed now 495 uint16OpID uint16 // A local recording for the uint16 ID of channel operation executed now 496 } 497 498 type m struct { 499 g0 *g // goroutine with scheduling stack 500 morebuf gobuf // gobuf arg to morestack 501 divmod uint32 // div/mod denominator for arm - known to liblink 502 503 // Fields not known to debuggers. 504 procid uint64 // for debuggers, but offset not hard-coded 505 gsignal *g // signal-handling g 506 goSigStack gsignalStack // Go-allocated signal handling stack 507 sigmask sigset // storage for saved signal mask 508 tls [6]uintptr // thread-local storage (for x86 extern register) 509 mstartfn func() 510 curg *g // current running goroutine 511 caughtsig guintptr // goroutine running during fatal signal 512 p puintptr // attached p for executing go code (nil if not executing go code) 513 nextp puintptr 514 oldp puintptr // the p that was attached before executing a syscall 515 id int64 516 mallocing int32 517 throwing int32 518 preemptoff string // if != "", keep curg running on this m 519 locks int32 520 dying int32 521 profilehz int32 522 spinning bool // m is out of work and is actively looking for work 523 blocked bool // m is blocked on a note 524 newSigstack bool // minit on C thread called sigaltstack 525 printlock int8 526 incgo bool // m is executing a cgo call 527 freeWait uint32 // if == 0, safe to free g0 and delete m (atomic) 528 fastrand [2]uint32 529 needextram bool 530 traceback uint8 531 ncgocall uint64 // number of cgo calls in total 532 ncgo int32 // number of cgo calls currently in progress 533 cgoCallersUse uint32 // if non-zero, cgoCallers in use temporarily 534 cgoCallers *cgoCallers // cgo traceback if crashing in cgo call 535 doesPark bool // non-P running threads: sysmon and newmHandoff never use .park 536 park note 537 alllink *m // on allm 538 schedlink muintptr 539 lockedg guintptr 540 createstack [32]uintptr // stack that created this thread. 541 lockedExt uint32 // tracking for external LockOSThread 542 lockedInt uint32 // tracking for internal lockOSThread 543 nextwaitm muintptr // next m waiting for lock 544 waitunlockf func(*g, unsafe.Pointer) bool 545 waitlock unsafe.Pointer 546 waittraceev byte 547 waittraceskip int 548 startingtrace bool 549 syscalltick uint32 550 freelink *m // on sched.freem 551 552 // mFixup is used to synchronize OS related m state 553 // (credentials etc) use mutex to access. To avoid deadlocks 554 // an atomic.Load() of used being zero in mDoFixupFn() 555 // guarantees fn is nil. 556 mFixup struct { 557 lock mutex 558 used uint32 559 fn func(bool) bool 560 } 561 562 // these are here because they are too large to be on the stack 563 // of low-level NOSPLIT functions. 564 libcall libcall 565 libcallpc uintptr // for cpu profiler 566 libcallsp uintptr 567 libcallg guintptr 568 syscall libcall // stores syscall parameters on windows 569 570 vdsoSP uintptr // SP for traceback while in VDSO call (0 if not in call) 571 vdsoPC uintptr // PC for traceback while in VDSO call 572 573 // preemptGen counts the number of completed preemption 574 // signals. This is used to detect when a preemption is 575 // requested, but fails. Accessed atomically. 576 preemptGen uint32 577 578 // Whether this is a pending preemption signal on this M. 579 // Accessed atomically. 580 signalPending uint32 581 582 dlogPerM 583 584 mOS 585 586 // Up to 10 locks held by this m, maintained by the lock ranking code. 587 locksHeldLen int 588 locksHeld [10]heldLockInfo 589 } 590 591 type p struct { 592 id int32 593 status uint32 // one of pidle/prunning/... 594 link puintptr 595 schedtick uint32 // incremented on every scheduler call 596 syscalltick uint32 // incremented on every system call 597 sysmontick sysmontick // last tick observed by sysmon 598 m muintptr // back-link to associated m (nil if idle) 599 mcache *mcache 600 pcache pageCache 601 raceprocctx uintptr 602 603 deferpool [5][]*_defer // pool of available defer structs of different sizes (see panic.go) 604 deferpoolbuf [5][32]*_defer 605 606 // Cache of goroutine ids, amortizes accesses to runtime·sched.goidgen. 607 goidcache uint64 608 goidcacheend uint64 609 610 // Queue of runnable goroutines. Accessed without lock. 611 runqhead uint32 612 runqtail uint32 613 runq [256]guintptr 614 // runnext, if non-nil, is a runnable G that was ready'd by 615 // the current G and should be run next instead of what's in 616 // runq if there's time remaining in the running G's time 617 // slice. It will inherit the time left in the current time 618 // slice. If a set of goroutines is locked in a 619 // communicate-and-wait pattern, this schedules that set as a 620 // unit and eliminates the (potentially large) scheduling 621 // latency that otherwise arises from adding the ready'd 622 // goroutines to the end of the run queue. 623 runnext guintptr 624 625 // Available G's (status == Gdead) 626 gFree struct { 627 gList 628 n int32 629 } 630 631 sudogcache []*sudog 632 sudogbuf [128]*sudog 633 634 // Cache of mspan objects from the heap. 635 mspancache struct { 636 // We need an explicit length here because this field is used 637 // in allocation codepaths where write barriers are not allowed, 638 // and eliminating the write barrier/keeping it eliminated from 639 // slice updates is tricky, moreso than just managing the length 640 // ourselves. 641 len int 642 buf [128]*mspan 643 } 644 645 tracebuf traceBufPtr 646 647 // traceSweep indicates the sweep events should be traced. 648 // This is used to defer the sweep start event until a span 649 // has actually been swept. 650 traceSweep bool 651 // traceSwept and traceReclaimed track the number of bytes 652 // swept and reclaimed by sweeping in the current sweep loop. 653 traceSwept, traceReclaimed uintptr 654 655 palloc persistentAlloc // per-P to avoid mutex 656 657 _ uint32 // Alignment for atomic fields below 658 659 // The when field of the first entry on the timer heap. 660 // This is updated using atomic functions. 661 // This is 0 if the timer heap is empty. 662 timer0When uint64 663 664 // The earliest known nextwhen field of a timer with 665 // timerModifiedEarlier status. Because the timer may have been 666 // modified again, there need not be any timer with this value. 667 // This is updated using atomic functions. 668 // This is 0 if the value is unknown. 669 timerModifiedEarliest uint64 670 671 // Per-P GC state 672 gcAssistTime int64 // Nanoseconds in assistAlloc 673 gcFractionalMarkTime int64 // Nanoseconds in fractional mark worker (atomic) 674 675 // gcMarkWorkerMode is the mode for the next mark worker to run in. 676 // That is, this is used to communicate with the worker goroutine 677 // selected for immediate execution by 678 // gcController.findRunnableGCWorker. When scheduling other goroutines, 679 // this field must be set to gcMarkWorkerNotWorker. 680 gcMarkWorkerMode gcMarkWorkerMode 681 // gcMarkWorkerStartTime is the nanotime() at which the most recent 682 // mark worker started. 683 gcMarkWorkerStartTime int64 684 685 // gcw is this P's GC work buffer cache. The work buffer is 686 // filled by write barriers, drained by mutator assists, and 687 // disposed on certain GC state transitions. 688 gcw gcWork 689 690 // wbBuf is this P's GC write barrier buffer. 691 // 692 // TODO: Consider caching this in the running G. 693 wbBuf wbBuf 694 695 runSafePointFn uint32 // if 1, run sched.safePointFn at next safe point 696 697 // statsSeq is a counter indicating whether this P is currently 698 // writing any stats. Its value is even when not, odd when it is. 699 statsSeq uint32 700 701 // Lock for timers. We normally access the timers while running 702 // on this P, but the scheduler can also do it from a different P. 703 timersLock mutex 704 705 // Actions to take at some time. This is used to implement the 706 // standard library's time package. 707 // Must hold timersLock to access. 708 timers []*timer 709 710 // Number of timers in P's heap. 711 // Modified using atomic instructions. 712 numTimers uint32 713 714 // Number of timerModifiedEarlier timers on P's heap. 715 // This should only be modified while holding timersLock, 716 // or while the timer status is in a transient state 717 // such as timerModifying. 718 adjustTimers uint32 719 720 // Number of timerDeleted timers in P's heap. 721 // Modified using atomic instructions. 722 deletedTimers uint32 723 724 // Race context used while executing timer functions. 725 timerRaceCtx uintptr 726 727 // preempt is set to indicate that this P should be enter the 728 // scheduler ASAP (regardless of what G is running on it). 729 preempt bool 730 731 pad cpu.CacheLinePad 732 } 733 734 type schedt struct { 735 // accessed atomically. keep at top to ensure alignment on 32-bit systems. 736 goidgen uint64 737 lastpoll uint64 // time of last network poll, 0 if currently polling 738 pollUntil uint64 // time to which current poll is sleeping 739 740 lock mutex 741 742 // When increasing nmidle, nmidlelocked, nmsys, or nmfreed, be 743 // sure to call checkdead(). 744 745 midle muintptr // idle m's waiting for work 746 nmidle int32 // number of idle m's waiting for work 747 nmidlelocked int32 // number of locked m's waiting for work 748 mnext int64 // number of m's that have been created and next M ID 749 maxmcount int32 // maximum number of m's allowed (or die) 750 nmsys int32 // number of system m's not counted for deadlock 751 nmfreed int64 // cumulative number of freed m's 752 753 ngsys uint32 // number of system goroutines; updated atomically 754 755 pidle puintptr // idle p's 756 npidle uint32 757 nmspinning uint32 // See "Worker thread parking/unparking" comment in proc.go. 758 759 // Global runnable queue. 760 runq gQueue 761 runqsize int32 762 763 // disable controls selective disabling of the scheduler. 764 // 765 // Use schedEnableUser to control this. 766 // 767 // disable is protected by sched.lock. 768 disable struct { 769 // user disables scheduling of user goroutines. 770 user bool 771 runnable gQueue // pending runnable Gs 772 n int32 // length of runnable 773 } 774 775 // Global cache of dead G's. 776 gFree struct { 777 lock mutex 778 stack gList // Gs with stacks 779 noStack gList // Gs without stacks 780 n int32 781 } 782 783 // Central cache of sudog structs. 784 sudoglock mutex 785 sudogcache *sudog 786 787 // Central pool of available defer structs of different sizes. 788 deferlock mutex 789 deferpool [5]*_defer 790 791 // freem is the list of m's waiting to be freed when their 792 // m.exited is set. Linked through m.freelink. 793 freem *m 794 795 gcwaiting uint32 // gc is waiting to run 796 stopwait int32 797 stopnote note 798 sysmonwait uint32 799 sysmonnote note 800 801 // While true, sysmon not ready for mFixup calls. 802 // Accessed atomically. 803 sysmonStarting uint32 804 805 // safepointFn should be called on each P at the next GC 806 // safepoint if p.runSafePointFn is set. 807 safePointFn func(*p) 808 safePointWait int32 809 safePointNote note 810 811 profilehz int32 // cpu profiling rate 812 813 procresizetime int64 // nanotime() of last change to gomaxprocs 814 totaltime int64 // ∫gomaxprocs dt up to procresizetime 815 816 // sysmonlock protects sysmon's actions on the runtime. 817 // 818 // Acquire and hold this mutex to block sysmon from interacting 819 // with the rest of the runtime. 820 sysmonlock mutex 821 } 822 823 // Values for the flags field of a sigTabT. 824 const ( 825 _SigNotify = 1 << iota // let signal.Notify have signal, even if from kernel 826 _SigKill // if signal.Notify doesn't take it, exit quietly 827 _SigThrow // if signal.Notify doesn't take it, exit loudly 828 _SigPanic // if the signal is from the kernel, panic 829 _SigDefault // if the signal isn't explicitly requested, don't monitor it 830 _SigGoExit // cause all runtime procs to exit (only used on Plan 9). 831 _SigSetStack // add SA_ONSTACK to libc handler 832 _SigUnblock // always unblock; see blockableSig 833 _SigIgn // _SIG_DFL action is to ignore the signal 834 ) 835 836 // Layout of in-memory per-function information prepared by linker 837 // See https://golang.org/s/go12symtab. 838 // Keep in sync with linker (../cmd/link/internal/ld/pcln.go:/pclntab) 839 // and with package debug/gosym and with symtab.go in package runtime. 840 type _func struct { 841 entry uintptr // start pc 842 nameoff int32 // function name 843 844 args int32 // in/out args size 845 deferreturn uint32 // offset of start of a deferreturn call instruction from entry, if any. 846 847 pcsp uint32 848 pcfile uint32 849 pcln uint32 850 npcdata uint32 851 cuOffset uint32 // runtime.cutab offset of this function's CU 852 funcID funcID // set for certain special runtime functions 853 _ [2]byte // pad 854 nfuncdata uint8 // must be last 855 } 856 857 // Pseudo-Func that is returned for PCs that occur in inlined code. 858 // A *Func can be either a *_func or a *funcinl, and they are distinguished 859 // by the first uintptr. 860 type funcinl struct { 861 zero uintptr // set to 0 to distinguish from _func 862 entry uintptr // entry of the real (the "outermost") frame. 863 name string 864 file string 865 line int 866 } 867 868 // layout of Itab known to compilers 869 // allocated in non-garbage-collected memory 870 // Needs to be in sync with 871 // ../cmd/compile/internal/gc/reflect.go:/^func.dumptabs. 872 type itab struct { 873 inter *interfacetype 874 _type *_type 875 hash uint32 // copy of _type.hash. Used for type switches. 876 _ [4]byte 877 fun [1]uintptr // variable sized. fun[0]==0 means _type does not implement inter. 878 } 879 880 // Lock-free stack node. 881 // Also known to export_test.go. 882 type lfnode struct { 883 next uint64 884 pushcnt uintptr 885 } 886 887 type forcegcstate struct { 888 lock mutex 889 g *g 890 idle uint32 891 } 892 893 // extendRandom extends the random numbers in r[:n] to the whole slice r. 894 // Treats n<0 as n==0. 895 func extendRandom(r []byte, n int) { 896 if n < 0 { 897 n = 0 898 } 899 for n < len(r) { 900 // Extend random bits using hash function & time seed 901 w := n 902 if w > 16 { 903 w = 16 904 } 905 h := memhash(unsafe.Pointer(&r[n-w]), uintptr(nanotime()), uintptr(w)) 906 for i := 0; i < sys.PtrSize && n < len(r); i++ { 907 r[n] = byte(h) 908 n++ 909 h >>= 8 910 } 911 } 912 } 913 914 // A _defer holds an entry on the list of deferred calls. 915 // If you add a field here, add code to clear it in freedefer and deferProcStack 916 // This struct must match the code in cmd/compile/internal/gc/reflect.go:deferstruct 917 // and cmd/compile/internal/gc/ssa.go:(*state).call. 918 // Some defers will be allocated on the stack and some on the heap. 919 // All defers are logically part of the stack, so write barriers to 920 // initialize them are not required. All defers must be manually scanned, 921 // and for heap defers, marked. 922 type _defer struct { 923 siz int32 // includes both arguments and results 924 started bool 925 heap bool 926 // openDefer indicates that this _defer is for a frame with open-coded 927 // defers. We have only one defer record for the entire frame (which may 928 // currently have 0, 1, or more defers active). 929 openDefer bool 930 sp uintptr // sp at time of defer 931 pc uintptr // pc at time of defer 932 fn *funcval // can be nil for open-coded defers 933 _panic *_panic // panic that is running defer 934 link *_defer 935 936 // If openDefer is true, the fields below record values about the stack 937 // frame and associated function that has the open-coded defer(s). sp 938 // above will be the sp for the frame, and pc will be address of the 939 // deferreturn call in the function. 940 fd unsafe.Pointer // funcdata for the function associated with the frame 941 varp uintptr // value of varp for the stack frame 942 // framepc is the current pc associated with the stack frame. Together, 943 // with sp above (which is the sp associated with the stack frame), 944 // framepc/sp can be used as pc/sp pair to continue a stack trace via 945 // gentraceback(). 946 framepc uintptr 947 } 948 949 // A _panic holds information about an active panic. 950 // 951 // A _panic value must only ever live on the stack. 952 // 953 // The argp and link fields are stack pointers, but don't need special 954 // handling during stack growth: because they are pointer-typed and 955 // _panic values only live on the stack, regular stack pointer 956 // adjustment takes care of them. 957 type _panic struct { 958 argp unsafe.Pointer // pointer to arguments of deferred call run during panic; cannot move - known to liblink 959 arg interface{} // argument to panic 960 link *_panic // link to earlier panic 961 pc uintptr // where to return to in runtime if this panic is bypassed 962 sp unsafe.Pointer // where to return to in runtime if this panic is bypassed 963 recovered bool // whether this panic is over 964 aborted bool // the panic was aborted 965 goexit bool 966 } 967 968 // stack traces 969 type stkframe struct { 970 fn funcInfo // function being run 971 pc uintptr // program counter within fn 972 continpc uintptr // program counter where execution can continue, or 0 if not 973 lr uintptr // program counter at caller aka link register 974 sp uintptr // stack pointer at pc 975 fp uintptr // stack pointer at caller aka frame pointer 976 varp uintptr // top of local variables 977 argp uintptr // pointer to function arguments 978 arglen uintptr // number of bytes at argp 979 argmap *bitvector // force use of this argmap 980 } 981 982 // ancestorInfo records details of where a goroutine was started. 983 type ancestorInfo struct { 984 pcs []uintptr // pcs from the stack of this goroutine 985 goid int64 // goroutine id of this goroutine; original goroutine possibly dead 986 gopc uintptr // pc of go statement that created this goroutine 987 } 988 989 const ( 990 _TraceRuntimeFrames = 1 << iota // include frames for internal runtime functions. 991 _TraceTrap // the initial PC, SP are from a trap, not a return PC from a call 992 _TraceJumpStack // if traceback is on a systemstack, resume trace at g that called into it 993 ) 994 995 // The maximum number of frames we print for a traceback 996 const _TracebackMaxFrames = 100 997 998 // A waitReason explains why a goroutine has been stopped. 999 // See gopark. Do not re-use waitReasons, add new ones. 1000 type waitReason uint8 1001 1002 const ( 1003 waitReasonZero waitReason = iota // "" 1004 waitReasonGCAssistMarking // "GC assist marking" 1005 waitReasonIOWait // "IO wait" 1006 waitReasonChanReceiveNilChan // "chan receive (nil chan)" 1007 waitReasonChanSendNilChan // "chan send (nil chan)" 1008 waitReasonDumpingHeap // "dumping heap" 1009 waitReasonGarbageCollection // "garbage collection" 1010 waitReasonGarbageCollectionScan // "garbage collection scan" 1011 waitReasonPanicWait // "panicwait" 1012 waitReasonSelect // "select" 1013 waitReasonSelectNoCases // "select (no cases)" 1014 waitReasonGCAssistWait // "GC assist wait" 1015 waitReasonGCSweepWait // "GC sweep wait" 1016 waitReasonGCScavengeWait // "GC scavenge wait" 1017 waitReasonChanReceive // "chan receive" 1018 waitReasonChanSend // "chan send" 1019 waitReasonFinalizerWait // "finalizer wait" 1020 waitReasonForceGCIdle // "force gc (idle)" 1021 waitReasonSemacquire // "semacquire" 1022 waitReasonSleep // "sleep" 1023 waitReasonSyncCondWait // "sync.Cond.Wait" 1024 waitReasonTimerGoroutineIdle // "timer goroutine (idle)" 1025 waitReasonTraceReaderBlocked // "trace reader (blocked)" 1026 waitReasonWaitForGCCycle // "wait for GC cycle" 1027 waitReasonGCWorkerIdle // "GC worker (idle)" 1028 waitReasonPreempted // "preempted" 1029 waitReasonDebugCall // "debug call" 1030 ) 1031 1032 var waitReasonStrings = [...]string{ 1033 waitReasonZero: "", 1034 waitReasonGCAssistMarking: "GC assist marking", 1035 waitReasonIOWait: "IO wait", 1036 waitReasonChanReceiveNilChan: "chan receive (nil chan)", 1037 waitReasonChanSendNilChan: "chan send (nil chan)", 1038 waitReasonDumpingHeap: "dumping heap", 1039 waitReasonGarbageCollection: "garbage collection", 1040 waitReasonGarbageCollectionScan: "garbage collection scan", 1041 waitReasonPanicWait: "panicwait", 1042 waitReasonSelect: "select", 1043 waitReasonSelectNoCases: "select (no cases)", 1044 waitReasonGCAssistWait: "GC assist wait", 1045 waitReasonGCSweepWait: "GC sweep wait", 1046 waitReasonGCScavengeWait: "GC scavenge wait", 1047 waitReasonChanReceive: "chan receive", 1048 waitReasonChanSend: "chan send", 1049 waitReasonFinalizerWait: "finalizer wait", 1050 waitReasonForceGCIdle: "force gc (idle)", 1051 waitReasonSemacquire: "semacquire", 1052 waitReasonSleep: "sleep", 1053 waitReasonSyncCondWait: "sync.Cond.Wait", 1054 waitReasonTimerGoroutineIdle: "timer goroutine (idle)", 1055 waitReasonTraceReaderBlocked: "trace reader (blocked)", 1056 waitReasonWaitForGCCycle: "wait for GC cycle", 1057 waitReasonGCWorkerIdle: "GC worker (idle)", 1058 waitReasonPreempted: "preempted", 1059 waitReasonDebugCall: "debug call", 1060 } 1061 1062 func (w waitReason) String() string { 1063 if w < 0 || w >= waitReason(len(waitReasonStrings)) { 1064 return "unknown wait reason" 1065 } 1066 return waitReasonStrings[w] 1067 } 1068 1069 var ( 1070 allm *m 1071 gomaxprocs int32 1072 ncpu int32 1073 forcegc forcegcstate 1074 sched schedt 1075 newprocs int32 1076 1077 // allpLock protects P-less reads and size changes of allp, idlepMask, 1078 // and timerpMask, and all writes to allp. 1079 allpLock mutex 1080 // len(allp) == gomaxprocs; may change at safe points, otherwise 1081 // immutable. 1082 allp []*p 1083 // Bitmask of Ps in _Pidle list, one bit per P. Reads and writes must 1084 // be atomic. Length may change at safe points. 1085 // 1086 // Each P must update only its own bit. In order to maintain 1087 // consistency, a P going idle must the idle mask simultaneously with 1088 // updates to the idle P list under the sched.lock, otherwise a racing 1089 // pidleget may clear the mask before pidleput sets the mask, 1090 // corrupting the bitmap. 1091 // 1092 // N.B., procresize takes ownership of all Ps in stopTheWorldWithSema. 1093 idlepMask pMask 1094 // Bitmask of Ps that may have a timer, one bit per P. Reads and writes 1095 // must be atomic. Length may change at safe points. 1096 timerpMask pMask 1097 1098 // Pool of GC parked background workers. Entries are type 1099 // *gcBgMarkWorkerNode. 1100 gcBgMarkWorkerPool lfstack 1101 1102 // Total number of gcBgMarkWorker goroutines. Protected by worldsema. 1103 gcBgMarkWorkerCount int32 1104 1105 // Information about what cpu features are available. 1106 // Packages outside the runtime should not use these 1107 // as they are not an external api. 1108 // Set on startup in asm_{386,amd64}.s 1109 processorVersionInfo uint32 1110 isIntel bool 1111 lfenceBeforeRdtsc bool 1112 1113 goarm uint8 // set by cmd/link on arm systems 1114 ) 1115 1116 // Set by the linker so the runtime can determine the buildmode. 1117 var ( 1118 islibrary bool // -buildmode=c-shared 1119 isarchive bool // -buildmode=c-archive 1120 ) 1121 1122 // Must agree with cmd/internal/objabi.Framepointer_enabled. 1123 const framepointer_enabled = GOARCH == "amd64" || GOARCH == "arm64" && (GOOS == "linux" || GOOS == "darwin" || GOOS == "ios")