Source file src/runtime/runtime2.go
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/abi" 9 "internal/chacha8rand" 10 "internal/goarch" 11 "internal/runtime/atomic" 12 "runtime/internal/sys" 13 "unsafe" 14 ) 15 16 // defined constants 17 const ( 18 // G status 19 // 20 // Beyond indicating the general state of a G, the G status 21 // acts like a lock on the goroutine's stack (and hence its 22 // ability to execute user code). 23 // 24 // If you add to this list, add to the list 25 // of "okay during garbage collection" status 26 // in mgcmark.go too. 27 // 28 // TODO(austin): The _Gscan bit could be much lighter-weight. 29 // For example, we could choose not to run _Gscanrunnable 30 // goroutines found in the run queue, rather than CAS-looping 31 // until they become _Grunnable. And transitions like 32 // _Gscanwaiting -> _Gscanrunnable are actually okay because 33 // they don't affect stack ownership. 34 35 // _Gidle means this goroutine was just allocated and has not 36 // yet been initialized. 37 _Gidle = iota // 0 38 39 // _Grunnable means this goroutine is on a run queue. It is 40 // not currently executing user code. The stack is not owned. 41 _Grunnable // 1 42 43 // _Grunning means this goroutine may execute user code. The 44 // stack is owned by this goroutine. It is not on a run queue. 45 // It is assigned an M and a P (g.m and g.m.p are valid). 46 _Grunning // 2 47 48 // _Gsyscall means this goroutine is executing a system call. 49 // It is not executing user code. The stack is owned by this 50 // goroutine. It is not on a run queue. It is assigned an M. 51 _Gsyscall // 3 52 53 // _Gwaiting means this goroutine is blocked in the runtime. 54 // It is not executing user code. It is not on a run queue, 55 // but should be recorded somewhere (e.g., a channel wait 56 // queue) so it can be ready()d when necessary. The stack is 57 // not owned *except* that a channel operation may read or 58 // write parts of the stack under the appropriate channel 59 // lock. Otherwise, it is not safe to access the stack after a 60 // goroutine enters _Gwaiting (e.g., it may get moved). 61 _Gwaiting // 4 62 63 // _Gmoribund_unused is currently unused, but hardcoded in gdb 64 // scripts. 65 _Gmoribund_unused // 5 66 67 // _Gdead means this goroutine is currently unused. It may be 68 // just exited, on a free list, or just being initialized. It 69 // is not executing user code. It may or may not have a stack 70 // allocated. The G and its stack (if any) are owned by the M 71 // that is exiting the G or that obtained the G from the free 72 // list. 73 _Gdead // 6 74 75 // _Genqueue_unused is currently unused. 76 _Genqueue_unused // 7 77 78 // _Gcopystack means this goroutine's stack is being moved. It 79 // is not executing user code and is not on a run queue. The 80 // stack is owned by the goroutine that put it in _Gcopystack. 81 _Gcopystack // 8 82 83 // _Gpreempted means this goroutine stopped itself for a 84 // suspendG preemption. It is like _Gwaiting, but nothing is 85 // yet responsible for ready()ing it. Some suspendG must CAS 86 // the status to _Gwaiting to take responsibility for 87 // ready()ing this G. 88 _Gpreempted // 9 89 90 // _Gscan combined with one of the above states other than 91 // _Grunning indicates that GC is scanning the stack. The 92 // goroutine is not executing user code and the stack is owned 93 // by the goroutine that set the _Gscan bit. 94 // 95 // _Gscanrunning is different: it is used to briefly block 96 // state transitions while GC signals the G to scan its own 97 // stack. This is otherwise like _Grunning. 98 // 99 // atomicstatus&~Gscan gives the state the goroutine will 100 // return to when the scan completes. 101 _Gscan = 0x1000 102 _Gscanrunnable = _Gscan + _Grunnable // 0x1001 103 _Gscanrunning = _Gscan + _Grunning // 0x1002 104 _Gscansyscall = _Gscan + _Gsyscall // 0x1003 105 _Gscanwaiting = _Gscan + _Gwaiting // 0x1004 106 _Gscanpreempted = _Gscan + _Gpreempted // 0x1009 107 ) 108 109 const ( 110 // P status 111 112 // _Pidle means a P is not being used to run user code or the 113 // scheduler. Typically, it's on the idle P list and available 114 // to the scheduler, but it may just be transitioning between 115 // other states. 116 // 117 // The P is owned by the idle list or by whatever is 118 // transitioning its state. Its run queue is empty. 119 _Pidle = iota 120 121 // _Prunning means a P is owned by an M and is being used to 122 // run user code or the scheduler. Only the M that owns this P 123 // is allowed to change the P's status from _Prunning. The M 124 // may transition the P to _Pidle (if it has no more work to 125 // do), _Psyscall (when entering a syscall), or _Pgcstop (to 126 // halt for the GC). The M may also hand ownership of the P 127 // off directly to another M (e.g., to schedule a locked G). 128 _Prunning 129 130 // _Psyscall means a P is not running user code. It has 131 // affinity to an M in a syscall but is not owned by it and 132 // may be stolen by another M. This is similar to _Pidle but 133 // uses lightweight transitions and maintains M affinity. 134 // 135 // Leaving _Psyscall must be done with a CAS, either to steal 136 // or retake the P. Note that there's an ABA hazard: even if 137 // an M successfully CASes its original P back to _Prunning 138 // after a syscall, it must understand the P may have been 139 // used by another M in the interim. 140 _Psyscall 141 142 // _Pgcstop means a P is halted for STW and owned by the M 143 // that stopped the world. The M that stopped the world 144 // continues to use its P, even in _Pgcstop. Transitioning 145 // from _Prunning to _Pgcstop causes an M to release its P and 146 // park. 147 // 148 // The P retains its run queue and startTheWorld will restart 149 // the scheduler on Ps with non-empty run queues. 150 _Pgcstop 151 152 // _Pdead means a P is no longer used (GOMAXPROCS shrank). We 153 // reuse Ps if GOMAXPROCS increases. A dead P is mostly 154 // stripped of its resources, though a few things remain 155 // (e.g., trace buffers). 156 _Pdead 157 ) 158 159 // Mutual exclusion locks. In the uncontended case, 160 // as fast as spin locks (just a few user-level instructions), 161 // but on the contention path they sleep in the kernel. 162 // A zeroed Mutex is unlocked (no need to initialize each lock). 163 // Initialization is helpful for static lock ranking, but not required. 164 type mutex struct { 165 // Empty struct if lock ranking is disabled, otherwise includes the lock rank 166 lockRankStruct 167 // Futex-based impl treats it as uint32 key, 168 // while sema-based impl as M* waitm. 169 // Used to be a union, but unions break precise GC. 170 key uintptr 171 } 172 173 // sleep and wakeup on one-time events. 174 // before any calls to notesleep or notewakeup, 175 // must call noteclear to initialize the Note. 176 // then, exactly one thread can call notesleep 177 // and exactly one thread can call notewakeup (once). 178 // once notewakeup has been called, the notesleep 179 // will return. future notesleep will return immediately. 180 // subsequent noteclear must be called only after 181 // previous notesleep has returned, e.g. it's disallowed 182 // to call noteclear straight after notewakeup. 183 // 184 // notetsleep is like notesleep but wakes up after 185 // a given number of nanoseconds even if the event 186 // has not yet happened. if a goroutine uses notetsleep to 187 // wake up early, it must wait to call noteclear until it 188 // can be sure that no other goroutine is calling 189 // notewakeup. 190 // 191 // notesleep/notetsleep are generally called on g0, 192 // notetsleepg is similar to notetsleep but is called on user g. 193 type note struct { 194 // Futex-based impl treats it as uint32 key, 195 // while sema-based impl as M* waitm. 196 // Used to be a union, but unions break precise GC. 197 key uintptr 198 } 199 200 type funcval struct { 201 fn uintptr 202 // variable-size, fn-specific data here 203 } 204 205 type iface struct { 206 tab *itab 207 data unsafe.Pointer 208 } 209 210 type eface struct { 211 _type *_type 212 data unsafe.Pointer 213 } 214 215 func efaceOf(ep *any) *eface { 216 return (*eface)(unsafe.Pointer(ep)) 217 } 218 219 // The guintptr, muintptr, and puintptr are all used to bypass write barriers. 220 // It is particularly important to avoid write barriers when the current P has 221 // been released, because the GC thinks the world is stopped, and an 222 // unexpected write barrier would not be synchronized with the GC, 223 // which can lead to a half-executed write barrier that has marked the object 224 // but not queued it. If the GC skips the object and completes before the 225 // queuing can occur, it will incorrectly free the object. 226 // 227 // We tried using special assignment functions invoked only when not 228 // holding a running P, but then some updates to a particular memory 229 // word went through write barriers and some did not. This breaks the 230 // write barrier shadow checking mode, and it is also scary: better to have 231 // a word that is completely ignored by the GC than to have one for which 232 // only a few updates are ignored. 233 // 234 // Gs and Ps are always reachable via true pointers in the 235 // allgs and allp lists or (during allocation before they reach those lists) 236 // from stack variables. 237 // 238 // Ms are always reachable via true pointers either from allm or 239 // freem. Unlike Gs and Ps we do free Ms, so it's important that 240 // nothing ever hold an muintptr across a safe point. 241 242 // A guintptr holds a goroutine pointer, but typed as a uintptr 243 // to bypass write barriers. It is used in the Gobuf goroutine state 244 // and in scheduling lists that are manipulated without a P. 245 // 246 // The Gobuf.g goroutine pointer is almost always updated by assembly code. 247 // In one of the few places it is updated by Go code - func save - it must be 248 // treated as a uintptr to avoid a write barrier being emitted at a bad time. 249 // Instead of figuring out how to emit the write barriers missing in the 250 // assembly manipulation, we change the type of the field to uintptr, 251 // so that it does not require write barriers at all. 252 // 253 // Goroutine structs are published in the allg list and never freed. 254 // That will keep the goroutine structs from being collected. 255 // There is never a time that Gobuf.g's contain the only references 256 // to a goroutine: the publishing of the goroutine in allg comes first. 257 // Goroutine pointers are also kept in non-GC-visible places like TLS, 258 // so I can't see them ever moving. If we did want to start moving data 259 // in the GC, we'd need to allocate the goroutine structs from an 260 // alternate arena. Using guintptr doesn't make that problem any worse. 261 // Note that pollDesc.rg, pollDesc.wg also store g in uintptr form, 262 // so they would need to be updated too if g's start moving. 263 type guintptr uintptr 264 265 //go:nosplit 266 func (gp guintptr) ptr() *g { return (*g)(unsafe.Pointer(gp)) } 267 268 //go:nosplit 269 func (gp *guintptr) set(g *g) { *gp = guintptr(unsafe.Pointer(g)) } 270 271 //go:nosplit 272 func (gp *guintptr) cas(old, new guintptr) bool { 273 return atomic.Casuintptr((*uintptr)(unsafe.Pointer(gp)), uintptr(old), uintptr(new)) 274 } 275 276 //go:nosplit 277 func (gp *g) guintptr() guintptr { 278 return guintptr(unsafe.Pointer(gp)) 279 } 280 281 // setGNoWB performs *gp = new without a write barrier. 282 // For times when it's impractical to use a guintptr. 283 // 284 //go:nosplit 285 //go:nowritebarrier 286 func setGNoWB(gp **g, new *g) { 287 (*guintptr)(unsafe.Pointer(gp)).set(new) 288 } 289 290 type puintptr uintptr 291 292 //go:nosplit 293 func (pp puintptr) ptr() *p { return (*p)(unsafe.Pointer(pp)) } 294 295 //go:nosplit 296 func (pp *puintptr) set(p *p) { *pp = puintptr(unsafe.Pointer(p)) } 297 298 // muintptr is a *m that is not tracked by the garbage collector. 299 // 300 // Because we do free Ms, there are some additional constrains on 301 // muintptrs: 302 // 303 // 1. Never hold an muintptr locally across a safe point. 304 // 305 // 2. Any muintptr in the heap must be owned by the M itself so it can 306 // ensure it is not in use when the last true *m is released. 307 type muintptr uintptr 308 309 //go:nosplit 310 func (mp muintptr) ptr() *m { return (*m)(unsafe.Pointer(mp)) } 311 312 //go:nosplit 313 func (mp *muintptr) set(m *m) { *mp = muintptr(unsafe.Pointer(m)) } 314 315 // setMNoWB performs *mp = new without a write barrier. 316 // For times when it's impractical to use an muintptr. 317 // 318 //go:nosplit 319 //go:nowritebarrier 320 func setMNoWB(mp **m, new *m) { 321 (*muintptr)(unsafe.Pointer(mp)).set(new) 322 } 323 324 type gobuf struct { 325 // The offsets of sp, pc, and g are known to (hard-coded in) libmach. 326 // 327 // ctxt is unusual with respect to GC: it may be a 328 // heap-allocated funcval, so GC needs to track it, but it 329 // needs to be set and cleared from assembly, where it's 330 // difficult to have write barriers. However, ctxt is really a 331 // saved, live register, and we only ever exchange it between 332 // the real register and the gobuf. Hence, we treat it as a 333 // root during stack scanning, which means assembly that saves 334 // and restores it doesn't need write barriers. It's still 335 // typed as a pointer so that any other writes from Go get 336 // write barriers. 337 sp uintptr 338 pc uintptr 339 g guintptr 340 ctxt unsafe.Pointer 341 ret uintptr 342 lr uintptr 343 bp uintptr // for framepointer-enabled architectures 344 } 345 346 // sudog (pseudo-g) represents a g in a wait list, such as for sending/receiving 347 // on a channel. 348 // 349 // sudog is necessary because the g ↔ synchronization object relation 350 // is many-to-many. A g can be on many wait lists, so there may be 351 // many sudogs for one g; and many gs may be waiting on the same 352 // synchronization object, so there may be many sudogs for one object. 353 // 354 // sudogs are allocated from a special pool. Use acquireSudog and 355 // releaseSudog to allocate and free them. 356 type sudog struct { 357 // The following fields are protected by the hchan.lock of the 358 // channel this sudog is blocking on. shrinkstack depends on 359 // this for sudogs involved in channel ops. 360 361 g *g 362 363 next *sudog 364 prev *sudog 365 elem unsafe.Pointer // data element (may point to stack) 366 367 // The following fields are never accessed concurrently. 368 // For channels, waitlink is only accessed by g. 369 // For semaphores, all fields (including the ones above) 370 // are only accessed when holding a semaRoot lock. 371 372 acquiretime int64 373 releasetime int64 374 ticket uint32 375 376 // isSelect indicates g is participating in a select, so 377 // g.selectDone must be CAS'd to win the wake-up race. 378 isSelect bool 379 380 // success indicates whether communication over channel c 381 // succeeded. It is true if the goroutine was awoken because a 382 // value was delivered over channel c, and false if awoken 383 // because c was closed. 384 success bool 385 386 // waiters is a count of semaRoot waiting list other than head of list, 387 // clamped to a uint16 to fit in unused space. 388 // Only meaningful at the head of the list. 389 // (If we wanted to be overly clever, we could store a high 16 bits 390 // in the second entry in the list.) 391 waiters uint16 392 393 parent *sudog // semaRoot binary tree 394 waitlink *sudog // g.waiting list or semaRoot 395 waittail *sudog // semaRoot 396 c *hchan // channel 397 } 398 399 type libcall struct { 400 fn uintptr 401 n uintptr // number of parameters 402 args uintptr // parameters 403 r1 uintptr // return values 404 r2 uintptr 405 err uintptr // error number 406 } 407 408 // Stack describes a Go execution stack. 409 // The bounds of the stack are exactly [lo, hi), 410 // with no implicit data structures on either side. 411 type stack struct { 412 lo uintptr 413 hi uintptr 414 } 415 416 // heldLockInfo gives info on a held lock and the rank of that lock 417 type heldLockInfo struct { 418 lockAddr uintptr 419 rank lockRank 420 } 421 422 type g struct { 423 // Stack parameters. 424 // stack describes the actual stack memory: [stack.lo, stack.hi). 425 // stackguard0 is the stack pointer compared in the Go stack growth prologue. 426 // It is stack.lo+StackGuard normally, but can be StackPreempt to trigger a preemption. 427 // stackguard1 is the stack pointer compared in the //go:systemstack stack growth prologue. 428 // It is stack.lo+StackGuard on g0 and gsignal stacks. 429 // It is ~0 on other goroutine stacks, to trigger a call to morestackc (and crash). 430 stack stack // offset known to runtime/cgo 431 stackguard0 uintptr // offset known to liblink 432 stackguard1 uintptr // offset known to liblink 433 434 _panic *_panic // innermost panic - offset known to liblink 435 _defer *_defer // innermost defer 436 m *m // current m; offset known to arm liblink 437 sched gobuf 438 syscallsp uintptr // if status==Gsyscall, syscallsp = sched.sp to use during gc 439 syscallpc uintptr // if status==Gsyscall, syscallpc = sched.pc to use during gc 440 syscallbp uintptr // if status==Gsyscall, syscallbp = sched.bp to use in fpTraceback 441 stktopsp uintptr // expected sp at top of stack, to check in traceback 442 // param is a generic pointer parameter field used to pass 443 // values in particular contexts where other storage for the 444 // parameter would be difficult to find. It is currently used 445 // in four ways: 446 // 1. When a channel operation wakes up a blocked goroutine, it sets param to 447 // point to the sudog of the completed blocking operation. 448 // 2. By gcAssistAlloc1 to signal back to its caller that the goroutine completed 449 // the GC cycle. It is unsafe to do so in any other way, because the goroutine's 450 // stack may have moved in the meantime. 451 // 3. By debugCallWrap to pass parameters to a new goroutine because allocating a 452 // closure in the runtime is forbidden. 453 // 4. When a panic is recovered and control returns to the respective frame, 454 // param may point to a savedOpenDeferState. 455 param unsafe.Pointer 456 atomicstatus atomic.Uint32 457 stackLock uint32 // sigprof/scang lock; TODO: fold in to atomicstatus 458 goid uint64 459 schedlink guintptr 460 waitsince int64 // approx time when the g become blocked 461 waitreason waitReason // if status==Gwaiting 462 463 preempt bool // preemption signal, duplicates stackguard0 = stackpreempt 464 preemptStop bool // transition to _Gpreempted on preemption; otherwise, just deschedule 465 preemptShrink bool // shrink stack at synchronous safe point 466 467 // asyncSafePoint is set if g is stopped at an asynchronous 468 // safe point. This means there are frames on the stack 469 // without precise pointer information. 470 asyncSafePoint bool 471 472 paniconfault bool // panic (instead of crash) on unexpected fault address 473 gcscandone bool // g has scanned stack; protected by _Gscan bit in status 474 throwsplit bool // must not split stack 475 // activeStackChans indicates that there are unlocked channels 476 // pointing into this goroutine's stack. If true, stack 477 // copying needs to acquire channel locks to protect these 478 // areas of the stack. 479 activeStackChans bool 480 // parkingOnChan indicates that the goroutine is about to 481 // park on a chansend or chanrecv. Used to signal an unsafe point 482 // for stack shrinking. 483 parkingOnChan atomic.Bool 484 // inMarkAssist indicates whether the goroutine is in mark assist. 485 // Used by the execution tracer. 486 inMarkAssist bool 487 coroexit bool // argument to coroswitch_m 488 489 raceignore int8 // ignore race detection events 490 nocgocallback bool // whether disable callback from C 491 tracking bool // whether we're tracking this G for sched latency statistics 492 trackingSeq uint8 // used to decide whether to track this G 493 trackingStamp int64 // timestamp of when the G last started being tracked 494 runnableTime int64 // the amount of time spent runnable, cleared when running, only used when tracking 495 lockedm muintptr 496 sig uint32 497 writebuf []byte 498 sigcode0 uintptr 499 sigcode1 uintptr 500 sigpc uintptr 501 parentGoid uint64 // goid of goroutine that created this goroutine 502 gopc uintptr // pc of go statement that created this goroutine 503 ancestors *[]ancestorInfo // ancestor information goroutine(s) that created this goroutine (only used if debug.tracebackancestors) 504 startpc uintptr // pc of goroutine function 505 racectx uintptr 506 waiting *sudog // sudog structures this g is waiting on (that have a valid elem ptr); in lock order 507 cgoCtxt []uintptr // cgo traceback context 508 labels unsafe.Pointer // profiler labels 509 timer *timer // cached timer for time.Sleep 510 sleepWhen int64 // when to sleep until 511 selectDone atomic.Uint32 // are we participating in a select and did someone win the race? 512 513 // goroutineProfiled indicates the status of this goroutine's stack for the 514 // current in-progress goroutine profile 515 goroutineProfiled goroutineProfileStateHolder 516 517 coroarg *coro // argument during coroutine transfers 518 519 // Per-G tracer state. 520 trace gTraceState 521 522 // Per-G GC state 523 524 // gcAssistBytes is this G's GC assist credit in terms of 525 // bytes allocated. If this is positive, then the G has credit 526 // to allocate gcAssistBytes bytes without assisting. If this 527 // is negative, then the G must correct this by performing 528 // scan work. We track this in bytes to make it fast to update 529 // and check for debt in the malloc hot path. The assist ratio 530 // determines how this corresponds to scan work debt. 531 gcAssistBytes int64 532 } 533 534 // gTrackingPeriod is the number of transitions out of _Grunning between 535 // latency tracking runs. 536 const gTrackingPeriod = 8 537 538 const ( 539 // tlsSlots is the number of pointer-sized slots reserved for TLS on some platforms, 540 // like Windows. 541 tlsSlots = 6 542 tlsSize = tlsSlots * goarch.PtrSize 543 ) 544 545 // Values for m.freeWait. 546 const ( 547 freeMStack = 0 // M done, free stack and reference. 548 freeMRef = 1 // M done, free reference. 549 freeMWait = 2 // M still in use. 550 ) 551 552 type m struct { 553 g0 *g // goroutine with scheduling stack 554 morebuf gobuf // gobuf arg to morestack 555 divmod uint32 // div/mod denominator for arm - known to liblink 556 _ uint32 // align next field to 8 bytes 557 558 // Fields not known to debuggers. 559 procid uint64 // for debuggers, but offset not hard-coded 560 gsignal *g // signal-handling g 561 goSigStack gsignalStack // Go-allocated signal handling stack 562 sigmask sigset // storage for saved signal mask 563 tls [tlsSlots]uintptr // thread-local storage (for x86 extern register) 564 mstartfn func() 565 curg *g // current running goroutine 566 caughtsig guintptr // goroutine running during fatal signal 567 p puintptr // attached p for executing go code (nil if not executing go code) 568 nextp puintptr 569 oldp puintptr // the p that was attached before executing a syscall 570 id int64 571 mallocing int32 572 throwing throwType 573 preemptoff string // if != "", keep curg running on this m 574 locks int32 575 dying int32 576 profilehz int32 577 spinning bool // m is out of work and is actively looking for work 578 blocked bool // m is blocked on a note 579 newSigstack bool // minit on C thread called sigaltstack 580 printlock int8 581 incgo bool // m is executing a cgo call 582 isextra bool // m is an extra m 583 isExtraInC bool // m is an extra m that is not executing Go code 584 isExtraInSig bool // m is an extra m in a signal handler 585 freeWait atomic.Uint32 // Whether it is safe to free g0 and delete m (one of freeMRef, freeMStack, freeMWait) 586 needextram bool 587 traceback uint8 588 ncgocall uint64 // number of cgo calls in total 589 ncgo int32 // number of cgo calls currently in progress 590 cgoCallersUse atomic.Uint32 // if non-zero, cgoCallers in use temporarily 591 cgoCallers *cgoCallers // cgo traceback if crashing in cgo call 592 park note 593 alllink *m // on allm 594 schedlink muintptr 595 lockedg guintptr 596 createstack [32]uintptr // stack that created this thread, it's used for StackRecord.Stack0, so it must align with it. 597 lockedExt uint32 // tracking for external LockOSThread 598 lockedInt uint32 // tracking for internal lockOSThread 599 nextwaitm muintptr // next m waiting for lock 600 601 mLockProfile mLockProfile // fields relating to runtime.lock contention 602 603 // wait* are used to carry arguments from gopark into park_m, because 604 // there's no stack to put them on. That is their sole purpose. 605 waitunlockf func(*g, unsafe.Pointer) bool 606 waitlock unsafe.Pointer 607 waitTraceSkip int 608 waitTraceBlockReason traceBlockReason 609 610 syscalltick uint32 611 freelink *m // on sched.freem 612 trace mTraceState 613 614 // these are here because they are too large to be on the stack 615 // of low-level NOSPLIT functions. 616 libcall libcall 617 libcallpc uintptr // for cpu profiler 618 libcallsp uintptr 619 libcallg guintptr 620 winsyscall winlibcall // stores syscall parameters on windows 621 622 vdsoSP uintptr // SP for traceback while in VDSO call (0 if not in call) 623 vdsoPC uintptr // PC for traceback while in VDSO call 624 625 // preemptGen counts the number of completed preemption 626 // signals. This is used to detect when a preemption is 627 // requested, but fails. 628 preemptGen atomic.Uint32 629 630 // Whether this is a pending preemption signal on this M. 631 signalPending atomic.Uint32 632 633 // pcvalue lookup cache 634 pcvalueCache pcvalueCache 635 636 dlogPerM 637 638 mOS 639 640 chacha8 chacha8rand.State 641 cheaprand uint64 642 643 // Up to 10 locks held by this m, maintained by the lock ranking code. 644 locksHeldLen int 645 locksHeld [10]heldLockInfo 646 } 647 648 type p struct { 649 id int32 650 status uint32 // one of pidle/prunning/... 651 link puintptr 652 schedtick uint32 // incremented on every scheduler call 653 syscalltick uint32 // incremented on every system call 654 sysmontick sysmontick // last tick observed by sysmon 655 m muintptr // back-link to associated m (nil if idle) 656 mcache *mcache 657 pcache pageCache 658 raceprocctx uintptr 659 660 deferpool []*_defer // pool of available defer structs (see panic.go) 661 deferpoolbuf [32]*_defer 662 663 // Cache of goroutine ids, amortizes accesses to runtime·sched.goidgen. 664 goidcache uint64 665 goidcacheend uint64 666 667 // Queue of runnable goroutines. Accessed without lock. 668 runqhead uint32 669 runqtail uint32 670 runq [256]guintptr 671 // runnext, if non-nil, is a runnable G that was ready'd by 672 // the current G and should be run next instead of what's in 673 // runq if there's time remaining in the running G's time 674 // slice. It will inherit the time left in the current time 675 // slice. If a set of goroutines is locked in a 676 // communicate-and-wait pattern, this schedules that set as a 677 // unit and eliminates the (potentially large) scheduling 678 // latency that otherwise arises from adding the ready'd 679 // goroutines to the end of the run queue. 680 // 681 // Note that while other P's may atomically CAS this to zero, 682 // only the owner P can CAS it to a valid G. 683 runnext guintptr 684 685 // Available G's (status == Gdead) 686 gFree struct { 687 gList 688 n int32 689 } 690 691 sudogcache []*sudog 692 sudogbuf [128]*sudog 693 694 // Cache of mspan objects from the heap. 695 mspancache struct { 696 // We need an explicit length here because this field is used 697 // in allocation codepaths where write barriers are not allowed, 698 // and eliminating the write barrier/keeping it eliminated from 699 // slice updates is tricky, more so than just managing the length 700 // ourselves. 701 len int 702 buf [128]*mspan 703 } 704 705 // Cache of a single pinner object to reduce allocations from repeated 706 // pinner creation. 707 pinnerCache *pinner 708 709 trace pTraceState 710 711 palloc persistentAlloc // per-P to avoid mutex 712 713 // Per-P GC state 714 gcAssistTime int64 // Nanoseconds in assistAlloc 715 gcFractionalMarkTime int64 // Nanoseconds in fractional mark worker (atomic) 716 717 // limiterEvent tracks events for the GC CPU limiter. 718 limiterEvent limiterEvent 719 720 // gcMarkWorkerMode is the mode for the next mark worker to run in. 721 // That is, this is used to communicate with the worker goroutine 722 // selected for immediate execution by 723 // gcController.findRunnableGCWorker. When scheduling other goroutines, 724 // this field must be set to gcMarkWorkerNotWorker. 725 gcMarkWorkerMode gcMarkWorkerMode 726 // gcMarkWorkerStartTime is the nanotime() at which the most recent 727 // mark worker started. 728 gcMarkWorkerStartTime int64 729 730 // gcw is this P's GC work buffer cache. The work buffer is 731 // filled by write barriers, drained by mutator assists, and 732 // disposed on certain GC state transitions. 733 gcw gcWork 734 735 // wbBuf is this P's GC write barrier buffer. 736 // 737 // TODO: Consider caching this in the running G. 738 wbBuf wbBuf 739 740 runSafePointFn uint32 // if 1, run sched.safePointFn at next safe point 741 742 // statsSeq is a counter indicating whether this P is currently 743 // writing any stats. Its value is even when not, odd when it is. 744 statsSeq atomic.Uint32 745 746 // Timer heap. 747 timers timers 748 749 // maxStackScanDelta accumulates the amount of stack space held by 750 // live goroutines (i.e. those eligible for stack scanning). 751 // Flushed to gcController.maxStackScan once maxStackScanSlack 752 // or -maxStackScanSlack is reached. 753 maxStackScanDelta int64 754 755 // gc-time statistics about current goroutines 756 // Note that this differs from maxStackScan in that this 757 // accumulates the actual stack observed to be used at GC time (hi - sp), 758 // not an instantaneous measure of the total stack size that might need 759 // to be scanned (hi - lo). 760 scannedStackSize uint64 // stack size of goroutines scanned by this P 761 scannedStacks uint64 // number of goroutines scanned by this P 762 763 // preempt is set to indicate that this P should be enter the 764 // scheduler ASAP (regardless of what G is running on it). 765 preempt bool 766 767 // gcStopTime is the nanotime timestamp that this P last entered _Pgcstop. 768 gcStopTime int64 769 770 // pageTraceBuf is a buffer for writing out page allocation/free/scavenge traces. 771 // 772 // Used only if GOEXPERIMENT=pagetrace. 773 pageTraceBuf pageTraceBuf 774 775 // Padding is no longer needed. False sharing is now not a worry because p is large enough 776 // that its size class is an integer multiple of the cache line size (for any of our architectures). 777 } 778 779 type schedt struct { 780 goidgen atomic.Uint64 781 lastpoll atomic.Int64 // time of last network poll, 0 if currently polling 782 pollUntil atomic.Int64 // time to which current poll is sleeping 783 784 lock mutex 785 786 // When increasing nmidle, nmidlelocked, nmsys, or nmfreed, be 787 // sure to call checkdead(). 788 789 midle muintptr // idle m's waiting for work 790 nmidle int32 // number of idle m's waiting for work 791 nmidlelocked int32 // number of locked m's waiting for work 792 mnext int64 // number of m's that have been created and next M ID 793 maxmcount int32 // maximum number of m's allowed (or die) 794 nmsys int32 // number of system m's not counted for deadlock 795 nmfreed int64 // cumulative number of freed m's 796 797 ngsys atomic.Int32 // number of system goroutines 798 799 pidle puintptr // idle p's 800 npidle atomic.Int32 801 nmspinning atomic.Int32 // See "Worker thread parking/unparking" comment in proc.go. 802 needspinning atomic.Uint32 // See "Delicate dance" comment in proc.go. Boolean. Must hold sched.lock to set to 1. 803 804 // Global runnable queue. 805 runq gQueue 806 runqsize int32 807 808 // disable controls selective disabling of the scheduler. 809 // 810 // Use schedEnableUser to control this. 811 // 812 // disable is protected by sched.lock. 813 disable struct { 814 // user disables scheduling of user goroutines. 815 user bool 816 runnable gQueue // pending runnable Gs 817 n int32 // length of runnable 818 } 819 820 // Global cache of dead G's. 821 gFree struct { 822 lock mutex 823 stack gList // Gs with stacks 824 noStack gList // Gs without stacks 825 n int32 826 } 827 828 // Central cache of sudog structs. 829 sudoglock mutex 830 sudogcache *sudog 831 832 // Central pool of available defer structs. 833 deferlock mutex 834 deferpool *_defer 835 836 // freem is the list of m's waiting to be freed when their 837 // m.exited is set. Linked through m.freelink. 838 freem *m 839 840 gcwaiting atomic.Bool // gc is waiting to run 841 stopwait int32 842 stopnote note 843 sysmonwait atomic.Bool 844 sysmonnote note 845 846 // safePointFn should be called on each P at the next GC 847 // safepoint if p.runSafePointFn is set. 848 safePointFn func(*p) 849 safePointWait int32 850 safePointNote note 851 852 profilehz int32 // cpu profiling rate 853 854 procresizetime int64 // nanotime() of last change to gomaxprocs 855 totaltime int64 // ∫gomaxprocs dt up to procresizetime 856 857 // sysmonlock protects sysmon's actions on the runtime. 858 // 859 // Acquire and hold this mutex to block sysmon from interacting 860 // with the rest of the runtime. 861 sysmonlock mutex 862 863 // timeToRun is a distribution of scheduling latencies, defined 864 // as the sum of time a G spends in the _Grunnable state before 865 // it transitions to _Grunning. 866 timeToRun timeHistogram 867 868 // idleTime is the total CPU time Ps have "spent" idle. 869 // 870 // Reset on each GC cycle. 871 idleTime atomic.Int64 872 873 // totalMutexWaitTime is the sum of time goroutines have spent in _Gwaiting 874 // with a waitreason of the form waitReasonSync{RW,}Mutex{R,}Lock. 875 totalMutexWaitTime atomic.Int64 876 877 // stwStoppingTimeGC/Other are distributions of stop-the-world stopping 878 // latencies, defined as the time taken by stopTheWorldWithSema to get 879 // all Ps to stop. stwStoppingTimeGC covers all GC-related STWs, 880 // stwStoppingTimeOther covers the others. 881 stwStoppingTimeGC timeHistogram 882 stwStoppingTimeOther timeHistogram 883 884 // stwTotalTimeGC/Other are distributions of stop-the-world total 885 // latencies, defined as the total time from stopTheWorldWithSema to 886 // startTheWorldWithSema. This is a superset of 887 // stwStoppingTimeGC/Other. stwTotalTimeGC covers all GC-related STWs, 888 // stwTotalTimeOther covers the others. 889 stwTotalTimeGC timeHistogram 890 stwTotalTimeOther timeHistogram 891 892 // totalRuntimeLockWaitTime (plus the value of lockWaitTime on each M in 893 // allm) is the sum of time goroutines have spent in _Grunnable and with an 894 // M, but waiting for locks within the runtime. This field stores the value 895 // for Ms that have exited. 896 totalRuntimeLockWaitTime atomic.Int64 897 } 898 899 // Values for the flags field of a sigTabT. 900 const ( 901 _SigNotify = 1 << iota // let signal.Notify have signal, even if from kernel 902 _SigKill // if signal.Notify doesn't take it, exit quietly 903 _SigThrow // if signal.Notify doesn't take it, exit loudly 904 _SigPanic // if the signal is from the kernel, panic 905 _SigDefault // if the signal isn't explicitly requested, don't monitor it 906 _SigGoExit // cause all runtime procs to exit (only used on Plan 9). 907 _SigSetStack // Don't explicitly install handler, but add SA_ONSTACK to existing libc handler 908 _SigUnblock // always unblock; see blockableSig 909 _SigIgn // _SIG_DFL action is to ignore the signal 910 ) 911 912 // Layout of in-memory per-function information prepared by linker 913 // See https://golang.org/s/go12symtab. 914 // Keep in sync with linker (../cmd/link/internal/ld/pcln.go:/pclntab) 915 // and with package debug/gosym and with symtab.go in package runtime. 916 type _func struct { 917 sys.NotInHeap // Only in static data 918 919 entryOff uint32 // start pc, as offset from moduledata.text/pcHeader.textStart 920 nameOff int32 // function name, as index into moduledata.funcnametab. 921 922 args int32 // in/out args size 923 deferreturn uint32 // offset of start of a deferreturn call instruction from entry, if any. 924 925 pcsp uint32 926 pcfile uint32 927 pcln uint32 928 npcdata uint32 929 cuOffset uint32 // runtime.cutab offset of this function's CU 930 startLine int32 // line number of start of function (func keyword/TEXT directive) 931 funcID abi.FuncID // set for certain special runtime functions 932 flag abi.FuncFlag 933 _ [1]byte // pad 934 nfuncdata uint8 // must be last, must end on a uint32-aligned boundary 935 936 // The end of the struct is followed immediately by two variable-length 937 // arrays that reference the pcdata and funcdata locations for this 938 // function. 939 940 // pcdata contains the offset into moduledata.pctab for the start of 941 // that index's table. e.g., 942 // &moduledata.pctab[_func.pcdata[_PCDATA_UnsafePoint]] is the start of 943 // the unsafe point table. 944 // 945 // An offset of 0 indicates that there is no table. 946 // 947 // pcdata [npcdata]uint32 948 949 // funcdata contains the offset past moduledata.gofunc which contains a 950 // pointer to that index's funcdata. e.g., 951 // *(moduledata.gofunc + _func.funcdata[_FUNCDATA_ArgsPointerMaps]) is 952 // the argument pointer map. 953 // 954 // An offset of ^uint32(0) indicates that there is no entry. 955 // 956 // funcdata [nfuncdata]uint32 957 } 958 959 // Pseudo-Func that is returned for PCs that occur in inlined code. 960 // A *Func can be either a *_func or a *funcinl, and they are distinguished 961 // by the first uintptr. 962 // 963 // TODO(austin): Can we merge this with inlinedCall? 964 type funcinl struct { 965 ones uint32 // set to ^0 to distinguish from _func 966 entry uintptr // entry of the real (the "outermost") frame 967 name string 968 file string 969 line int32 970 startLine int32 971 } 972 973 type itab = abi.ITab 974 975 // Lock-free stack node. 976 // Also known to export_test.go. 977 type lfnode struct { 978 next uint64 979 pushcnt uintptr 980 } 981 982 type forcegcstate struct { 983 lock mutex 984 g *g 985 idle atomic.Bool 986 } 987 988 // A _defer holds an entry on the list of deferred calls. 989 // If you add a field here, add code to clear it in deferProcStack. 990 // This struct must match the code in cmd/compile/internal/ssagen/ssa.go:deferstruct 991 // and cmd/compile/internal/ssagen/ssa.go:(*state).call. 992 // Some defers will be allocated on the stack and some on the heap. 993 // All defers are logically part of the stack, so write barriers to 994 // initialize them are not required. All defers must be manually scanned, 995 // and for heap defers, marked. 996 type _defer struct { 997 heap bool 998 rangefunc bool // true for rangefunc list 999 sp uintptr // sp at time of defer 1000 pc uintptr // pc at time of defer 1001 fn func() // can be nil for open-coded defers 1002 link *_defer // next defer on G; can point to either heap or stack! 1003 1004 // If rangefunc is true, *head is the head of the atomic linked list 1005 // during a range-over-func execution. 1006 head *atomic.Pointer[_defer] 1007 } 1008 1009 // A _panic holds information about an active panic. 1010 // 1011 // A _panic value must only ever live on the stack. 1012 // 1013 // The argp and link fields are stack pointers, but don't need special 1014 // handling during stack growth: because they are pointer-typed and 1015 // _panic values only live on the stack, regular stack pointer 1016 // adjustment takes care of them. 1017 type _panic struct { 1018 argp unsafe.Pointer // pointer to arguments of deferred call run during panic; cannot move - known to liblink 1019 arg any // argument to panic 1020 link *_panic // link to earlier panic 1021 1022 // startPC and startSP track where _panic.start was called. 1023 startPC uintptr 1024 startSP unsafe.Pointer 1025 1026 // The current stack frame that we're running deferred calls for. 1027 sp unsafe.Pointer 1028 lr uintptr 1029 fp unsafe.Pointer 1030 1031 // retpc stores the PC where the panic should jump back to, if the 1032 // function last returned by _panic.next() recovers the panic. 1033 retpc uintptr 1034 1035 // Extra state for handling open-coded defers. 1036 deferBitsPtr *uint8 1037 slotsPtr unsafe.Pointer 1038 1039 recovered bool // whether this panic has been recovered 1040 goexit bool 1041 deferreturn bool 1042 } 1043 1044 // savedOpenDeferState tracks the extra state from _panic that's 1045 // necessary for deferreturn to pick up where gopanic left off, 1046 // without needing to unwind the stack. 1047 type savedOpenDeferState struct { 1048 retpc uintptr 1049 deferBitsOffset uintptr 1050 slotsOffset uintptr 1051 } 1052 1053 // ancestorInfo records details of where a goroutine was started. 1054 type ancestorInfo struct { 1055 pcs []uintptr // pcs from the stack of this goroutine 1056 goid uint64 // goroutine id of this goroutine; original goroutine possibly dead 1057 gopc uintptr // pc of go statement that created this goroutine 1058 } 1059 1060 // A waitReason explains why a goroutine has been stopped. 1061 // See gopark. Do not re-use waitReasons, add new ones. 1062 type waitReason uint8 1063 1064 const ( 1065 waitReasonZero waitReason = iota // "" 1066 waitReasonGCAssistMarking // "GC assist marking" 1067 waitReasonIOWait // "IO wait" 1068 waitReasonChanReceiveNilChan // "chan receive (nil chan)" 1069 waitReasonChanSendNilChan // "chan send (nil chan)" 1070 waitReasonDumpingHeap // "dumping heap" 1071 waitReasonGarbageCollection // "garbage collection" 1072 waitReasonGarbageCollectionScan // "garbage collection scan" 1073 waitReasonPanicWait // "panicwait" 1074 waitReasonSelect // "select" 1075 waitReasonSelectNoCases // "select (no cases)" 1076 waitReasonGCAssistWait // "GC assist wait" 1077 waitReasonGCSweepWait // "GC sweep wait" 1078 waitReasonGCScavengeWait // "GC scavenge wait" 1079 waitReasonChanReceive // "chan receive" 1080 waitReasonChanSend // "chan send" 1081 waitReasonFinalizerWait // "finalizer wait" 1082 waitReasonForceGCIdle // "force gc (idle)" 1083 waitReasonSemacquire // "semacquire" 1084 waitReasonSleep // "sleep" 1085 waitReasonSyncCondWait // "sync.Cond.Wait" 1086 waitReasonSyncMutexLock // "sync.Mutex.Lock" 1087 waitReasonSyncRWMutexRLock // "sync.RWMutex.RLock" 1088 waitReasonSyncRWMutexLock // "sync.RWMutex.Lock" 1089 waitReasonTraceReaderBlocked // "trace reader (blocked)" 1090 waitReasonWaitForGCCycle // "wait for GC cycle" 1091 waitReasonGCWorkerIdle // "GC worker (idle)" 1092 waitReasonGCWorkerActive // "GC worker (active)" 1093 waitReasonPreempted // "preempted" 1094 waitReasonDebugCall // "debug call" 1095 waitReasonGCMarkTermination // "GC mark termination" 1096 waitReasonStoppingTheWorld // "stopping the world" 1097 waitReasonFlushProcCaches // "flushing proc caches" 1098 waitReasonTraceGoroutineStatus // "trace goroutine status" 1099 waitReasonTraceProcStatus // "trace proc status" 1100 waitReasonPageTraceFlush // "page trace flush" 1101 waitReasonCoroutine // "coroutine" 1102 ) 1103 1104 var waitReasonStrings = [...]string{ 1105 waitReasonZero: "", 1106 waitReasonGCAssistMarking: "GC assist marking", 1107 waitReasonIOWait: "IO wait", 1108 waitReasonChanReceiveNilChan: "chan receive (nil chan)", 1109 waitReasonChanSendNilChan: "chan send (nil chan)", 1110 waitReasonDumpingHeap: "dumping heap", 1111 waitReasonGarbageCollection: "garbage collection", 1112 waitReasonGarbageCollectionScan: "garbage collection scan", 1113 waitReasonPanicWait: "panicwait", 1114 waitReasonSelect: "select", 1115 waitReasonSelectNoCases: "select (no cases)", 1116 waitReasonGCAssistWait: "GC assist wait", 1117 waitReasonGCSweepWait: "GC sweep wait", 1118 waitReasonGCScavengeWait: "GC scavenge wait", 1119 waitReasonChanReceive: "chan receive", 1120 waitReasonChanSend: "chan send", 1121 waitReasonFinalizerWait: "finalizer wait", 1122 waitReasonForceGCIdle: "force gc (idle)", 1123 waitReasonSemacquire: "semacquire", 1124 waitReasonSleep: "sleep", 1125 waitReasonSyncCondWait: "sync.Cond.Wait", 1126 waitReasonSyncMutexLock: "sync.Mutex.Lock", 1127 waitReasonSyncRWMutexRLock: "sync.RWMutex.RLock", 1128 waitReasonSyncRWMutexLock: "sync.RWMutex.Lock", 1129 waitReasonTraceReaderBlocked: "trace reader (blocked)", 1130 waitReasonWaitForGCCycle: "wait for GC cycle", 1131 waitReasonGCWorkerIdle: "GC worker (idle)", 1132 waitReasonGCWorkerActive: "GC worker (active)", 1133 waitReasonPreempted: "preempted", 1134 waitReasonDebugCall: "debug call", 1135 waitReasonGCMarkTermination: "GC mark termination", 1136 waitReasonStoppingTheWorld: "stopping the world", 1137 waitReasonFlushProcCaches: "flushing proc caches", 1138 waitReasonTraceGoroutineStatus: "trace goroutine status", 1139 waitReasonTraceProcStatus: "trace proc status", 1140 waitReasonPageTraceFlush: "page trace flush", 1141 waitReasonCoroutine: "coroutine", 1142 } 1143 1144 func (w waitReason) String() string { 1145 if w < 0 || w >= waitReason(len(waitReasonStrings)) { 1146 return "unknown wait reason" 1147 } 1148 return waitReasonStrings[w] 1149 } 1150 1151 func (w waitReason) isMutexWait() bool { 1152 return w == waitReasonSyncMutexLock || 1153 w == waitReasonSyncRWMutexRLock || 1154 w == waitReasonSyncRWMutexLock 1155 } 1156 1157 func (w waitReason) isWaitingForGC() bool { 1158 return isWaitingForGC[w] 1159 } 1160 1161 // isWaitingForGC indicates that a goroutine is only entering _Gwaiting and 1162 // setting a waitReason because it needs to be able to let the GC take ownership 1163 // of its stack. The G is always actually executing on the system stack, in 1164 // these cases. 1165 // 1166 // TODO(mknyszek): Consider replacing this with a new dedicated G status. 1167 var isWaitingForGC = [len(waitReasonStrings)]bool{ 1168 waitReasonStoppingTheWorld: true, 1169 waitReasonGCMarkTermination: true, 1170 waitReasonGarbageCollection: true, 1171 waitReasonGarbageCollectionScan: true, 1172 waitReasonTraceGoroutineStatus: true, 1173 waitReasonTraceProcStatus: true, 1174 waitReasonPageTraceFlush: true, 1175 waitReasonGCAssistMarking: true, 1176 waitReasonGCWorkerActive: true, 1177 waitReasonFlushProcCaches: true, 1178 } 1179 1180 var ( 1181 allm *m 1182 gomaxprocs int32 1183 ncpu int32 1184 forcegc forcegcstate 1185 sched schedt 1186 newprocs int32 1187 ) 1188 1189 var ( 1190 // allpLock protects P-less reads and size changes of allp, idlepMask, 1191 // and timerpMask, and all writes to allp. 1192 allpLock mutex 1193 1194 // len(allp) == gomaxprocs; may change at safe points, otherwise 1195 // immutable. 1196 allp []*p 1197 1198 // Bitmask of Ps in _Pidle list, one bit per P. Reads and writes must 1199 // be atomic. Length may change at safe points. 1200 // 1201 // Each P must update only its own bit. In order to maintain 1202 // consistency, a P going idle must the idle mask simultaneously with 1203 // updates to the idle P list under the sched.lock, otherwise a racing 1204 // pidleget may clear the mask before pidleput sets the mask, 1205 // corrupting the bitmap. 1206 // 1207 // N.B., procresize takes ownership of all Ps in stopTheWorldWithSema. 1208 idlepMask pMask 1209 1210 // Bitmask of Ps that may have a timer, one bit per P. Reads and writes 1211 // must be atomic. Length may change at safe points. 1212 // 1213 // Ideally, the timer mask would be kept immediately consistent on any timer 1214 // operations. Unfortunately, updating a shared global data structure in the 1215 // timer hot path adds too much overhead in applications frequently switching 1216 // between no timers and some timers. 1217 // 1218 // As a compromise, the timer mask is updated only on pidleget / pidleput. A 1219 // running P (returned by pidleget) may add a timer at any time, so its mask 1220 // must be set. An idle P (passed to pidleput) cannot add new timers while 1221 // idle, so if it has no timers at that time, its mask may be cleared. 1222 // 1223 // Thus, we get the following effects on timer-stealing in findrunnable: 1224 // 1225 // - Idle Ps with no timers when they go idle are never checked in findrunnable 1226 // (for work- or timer-stealing; this is the ideal case). 1227 // - Running Ps must always be checked. 1228 // - Idle Ps whose timers are stolen must continue to be checked until they run 1229 // again, even after timer expiration. 1230 // 1231 // When the P starts running again, the mask should be set, as a timer may be 1232 // added at any time. 1233 // 1234 // TODO(prattmic): Additional targeted updates may improve the above cases. 1235 // e.g., updating the mask when stealing a timer. 1236 timerpMask pMask 1237 ) 1238 1239 var ( 1240 // Pool of GC parked background workers. Entries are type 1241 // *gcBgMarkWorkerNode. 1242 gcBgMarkWorkerPool lfstack 1243 1244 // Total number of gcBgMarkWorker goroutines. Protected by worldsema. 1245 gcBgMarkWorkerCount int32 1246 1247 // Information about what cpu features are available. 1248 // Packages outside the runtime should not use these 1249 // as they are not an external api. 1250 // Set on startup in asm_{386,amd64}.s 1251 processorVersionInfo uint32 1252 isIntel bool 1253 1254 // set by cmd/link on arm systems 1255 goarm uint8 1256 goarmsoftfp uint8 1257 ) 1258 1259 // Set by the linker so the runtime can determine the buildmode. 1260 var ( 1261 islibrary bool // -buildmode=c-shared 1262 isarchive bool // -buildmode=c-archive 1263 ) 1264 1265 // Must agree with internal/buildcfg.FramePointerEnabled. 1266 const framepointer_enabled = GOARCH == "amd64" || GOARCH == "arm64" 1267 1268 // getcallerfp returns the frame pointer of the caller of the caller 1269 // of this function. 1270 // 1271 //go:nosplit 1272 //go:noinline 1273 func getcallerfp() uintptr { 1274 fp := getfp() // This frame's FP. 1275 if fp != 0 { 1276 fp = *(*uintptr)(unsafe.Pointer(fp)) // The caller's FP. 1277 fp = *(*uintptr)(unsafe.Pointer(fp)) // The caller's caller's FP. 1278 } 1279 return fp 1280 } 1281