libgo/runtime/runtime.h

   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 #include "config.h"
   6
   7 #include "go-assert.h"
   8 #include <complex.h>
   9 #include <signal.h>
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include <string.h>
  13 #include <sys/types.h>
  14 #include <sys/stat.h>
  15 #include <fcntl.h>
  16 #include <unistd.h>
  17 #include <pthread.h>
  18 #include <semaphore.h>
  19 #include <ucontext.h>
  20
  21 #ifdef HAVE_SYS_MMAN_H
  22 #include <sys/mman.h>
  23 #endif
  24
  25 #include "interface.h"
  26 #include "go-alloc.h"
  27
  28 #define _STRINGIFY2_(x) #x
  29 #define _STRINGIFY_(x) _STRINGIFY2_(x)
  30 #define GOSYM_PREFIX _STRINGIFY_(__USER_LABEL_PREFIX__)
  31
  32 /* This file supports C files copied from the 6g runtime library.
  33    This is a version of the 6g runtime.h rewritten for gccgo's version
  34    of the code.  */
  35
  36 typedef signed int   int8    __attribute__ ((mode (QI)));
  37 typedef unsigned int uint8   __attribute__ ((mode (QI)));
  38 typedef signed int   int16   __attribute__ ((mode (HI)));
  39 typedef unsigned int uint16  __attribute__ ((mode (HI)));
  40 typedef signed int   int32   __attribute__ ((mode (SI)));
  41 typedef unsigned int uint32  __attribute__ ((mode (SI)));
  42 typedef signed int   int64   __attribute__ ((mode (DI)));
  43 typedef unsigned int uint64  __attribute__ ((mode (DI)));
  44 typedef float        float32 __attribute__ ((mode (SF)));
  45 typedef double       float64 __attribute__ ((mode (DF)));
  46 typedef signed int   intptr __attribute__ ((mode (pointer)));
  47 typedef unsigned int uintptr __attribute__ ((mode (pointer)));
  48
  49 typedef intptr          intgo; // Go's int
  50 typedef uintptr         uintgo; // Go's uint
  51
  52 /* Defined types.  */
  53
  54 typedef uint8                   bool;
  55 typedef uint8                   byte;
  56 typedef struct  Func            Func;
  57 typedef struct  G               G;
  58 typedef struct  Lock            Lock;
  59 typedef struct  M               M;
  60 typedef struct  P               P;
  61 typedef struct  Note            Note;
  62 typedef struct  String          String;
  63 typedef struct  FuncVal         FuncVal;
  64 typedef struct  SigTab          SigTab;
  65 typedef struct  MCache          MCache;
  66 typedef struct  FixAlloc        FixAlloc;
  67 typedef struct  Hchan           Hchan;
  68 typedef struct  Timers          Timers;
  69 typedef struct  Timer           Timer;
  70 typedef struct  GCStats         GCStats;
  71 typedef struct  LFNode          LFNode;
  72 typedef struct  ParFor          ParFor;
  73 typedef struct  ParForThread    ParForThread;
  74 typedef struct  CgoMal          CgoMal;
  75 typedef struct  PollDesc        PollDesc;
  76 typedef struct  DebugVars       DebugVars;
  77
  78 typedef struct  __go_open_array         Slice;
  79 typedef struct  __go_interface          Iface;
  80 typedef struct  __go_empty_interface    Eface;
  81 typedef struct  __go_type_descriptor    Type;
  82 typedef struct  __go_defer_stack        Defer;
  83 typedef struct  __go_panic_stack        Panic;
  84
  85 typedef struct  __go_ptr_type           PtrType;
  86 typedef struct  __go_func_type          FuncType;
  87 typedef struct  __go_interface_type     InterfaceType;
  88 typedef struct  __go_map_type           MapType;
  89 typedef struct  __go_channel_type       ChanType;
  90
  91 typedef struct  Traceback       Traceback;
  92
  93 typedef struct  Location        Location;
  94
  95 /*
  96  * Per-CPU declaration.
  97  */
  98 extern M*       runtime_m(void);
  99 extern G*       runtime_g(void);
 100
 101 extern M        runtime_m0;
 102 extern G        runtime_g0;
 103
 104 /*
 105  * defined constants
 106  */
 107 enum
 108 {
 109         // G status
 110         //
 111         // If you add to this list, add to the list
 112         // of "okay during garbage collection" status
 113         // in mgc0.c too.
 114         Gidle,
 115         Grunnable,
 116         Grunning,
 117         Gsyscall,
 118         Gwaiting,
 119         Gmoribund_unused,  // currently unused, but hardcoded in gdb scripts
 120         Gdead,
 121 };
 122 enum
 123 {
 124         // P status
 125         Pidle,
 126         Prunning,
 127         Psyscall,
 128         Pgcstop,
 129         Pdead,
 130 };
 131 enum
 132 {
 133         true    = 1,
 134         false   = 0,
 135 };
 136 enum
 137 {
 138         PtrSize = sizeof(void*),
 139 };
 140 enum
 141 {
 142         // Per-M stack segment cache size.
 143         StackCacheSize = 32,
 144         // Global <-> per-M stack segment cache transfer batch size.
 145         StackCacheBatch = 16,
 146 };
 147 /*
 148  * structures
 149  */
 150 struct  Lock
 151 {
 152         // Futex-based impl treats it as uint32 key,
 153         // while sema-based impl as M* waitm.
 154         // Used to be a union, but unions break precise GC.
 155         uintptr key;
 156 };
 157 struct  Note
 158 {
 159         // Futex-based impl treats it as uint32 key,
 160         // while sema-based impl as M* waitm.
 161         // Used to be a union, but unions break precise GC.
 162         uintptr key;
 163 };
 164 struct String
 165 {
 166         const byte*     str;
 167         intgo           len;
 168 };
 169 struct FuncVal
 170 {
 171         void    (*fn)(void);
 172         // variable-size, fn-specific data here
 173 };
 174 struct  GCStats
 175 {
 176         // the struct must consist of only uint64's,
 177         // because it is casted to uint64[].
 178         uint64  nhandoff;
 179         uint64  nhandoffcnt;
 180         uint64  nprocyield;
 181         uint64  nosyield;
 182         uint64  nsleep;
 183 };
 184
 185 // A location in the program, used for backtraces.
 186 struct  Location
 187 {
 188         uintptr pc;
 189         String  filename;
 190         String  function;
 191         intgo   lineno;
 192 };
 193
 194 struct  G
 195 {
 196         void*   closure;        // Closure value.
 197         Defer*  defer;
 198         Panic*  panic;
 199         void*   exception;      // current exception being thrown
 200         bool    is_foreign;     // whether current exception from other language
 201         void    *gcstack;       // if status==Gsyscall, gcstack = stackbase to use during gc
 202         uintptr gcstack_size;
 203         void*   gcnext_segment;
 204         void*   gcnext_sp;
 205         void*   gcinitial_sp;
 206         ucontext_t gcregs;
 207         byte*   entry;          // initial function
 208         void*   param;          // passed parameter on wakeup
 209         bool    fromgogo;       // reached from gogo
 210         int16   status;
 211         uint32  selgen;         // valid sudog pointer
 212         int64   goid;
 213         int64   waitsince;      // approx time when the G become blocked
 214         const char*     waitreason;     // if status==Gwaiting
 215         G*      schedlink;
 216         bool    ispanic;
 217         bool    issystem;       // do not output in stack dump
 218         bool    isbackground;   // ignore in deadlock detector
 219         M*      m;              // for debuggers, but offset not hard-coded
 220         M*      lockedm;
 221         int32   sig;
 222         int32   writenbuf;
 223         byte*   writebuf;
 224         uintptr sigcode0;
 225         uintptr sigcode1;
 226         // uintptr      sigpc;
 227         uintptr gopc;   // pc of go statement that created this goroutine
 228
 229         int32   ncgo;
 230         CgoMal* cgomal;
 231
 232         Traceback* traceback;
 233
 234         ucontext_t      context;
 235         void*           stack_context[10];
 236 };
 237
 238 struct  M
 239 {
 240         G*      g0;             // goroutine with scheduling stack
 241         G*      gsignal;        // signal-handling G
 242         byte*   gsignalstack;
 243         size_t  gsignalstacksize;
 244         void    (*mstartfn)(void);
 245         G*      curg;           // current running goroutine
 246         G*      caughtsig;      // goroutine running during fatal signal
 247         P*      p;              // attached P for executing Go code (nil if not executing Go code)
 248         P*      nextp;
 249         int32   id;
 250         int32   mallocing;
 251         int32   throwing;
 252         int32   gcing;
 253         int32   locks;
 254         int32   dying;
 255         int32   profilehz;
 256         int32   helpgc;
 257         bool    spinning;       // M is out of work and is actively looking for work
 258         bool    blocked;        // M is blocked on a Note
 259         uint32  fastrand;
 260         uint64  ncgocall;       // number of cgo calls in total
 261         int32   ncgo;           // number of cgo calls currently in progress
 262         CgoMal* cgomal;
 263         Note    park;
 264         M*      alllink;        // on allm
 265         M*      schedlink;
 266         MCache  *mcache;
 267         G*      lockedg;
 268         Location createstack[32];       // Stack that created this thread.
 269         uint32  locked; // tracking for LockOSThread
 270         M*      nextwaitm;      // next M waiting for lock
 271         uintptr waitsema;       // semaphore for parking on locks
 272         uint32  waitsemacount;
 273         uint32  waitsemalock;
 274         GCStats gcstats;
 275         bool    racecall;
 276         bool    needextram;
 277         bool    dropextram;     // for gccgo: drop after call is done.
 278         bool    (*waitunlockf)(G*, void*);
 279         void*   waitlock;
 280
 281         uintptr settype_buf[1024];
 282         uintptr settype_bufsize;
 283
 284         uintptr end[];
 285 };
 286
 287 struct P
 288 {
 289         Lock;
 290
 291         int32   id;
 292         uint32  status;         // one of Pidle/Prunning/...
 293         P*      link;
 294         uint32  schedtick;      // incremented on every scheduler call
 295         uint32  syscalltick;    // incremented on every system call
 296         M*      m;              // back-link to associated M (nil if idle)
 297         MCache* mcache;
 298         Defer*  deferpool;      // pool of available Defer structs (see panic.c)
 299
 300         // Cache of goroutine ids, amortizes accesses to runtime_sched.goidgen.
 301         uint64  goidcache;
 302         uint64  goidcacheend;
 303
 304         // Queue of runnable goroutines.
 305         uint32  runqhead;
 306         uint32  runqtail;
 307         G*      runq[256];
 308
 309         // Available G's (status == Gdead)
 310         G*      gfree;
 311         int32   gfreecnt;
 312
 313         byte    pad[64];
 314 };
 315
 316 // The m->locked word holds two pieces of state counting active calls to LockOSThread/lockOSThread.
 317 // The low bit (LockExternal) is a boolean reporting whether any LockOSThread call is active.
 318 // External locks are not recursive; a second lock is silently ignored.
 319 // The upper bits of m->lockedcount record the nesting depth of calls to lockOSThread
 320 // (counting up by LockInternal), popped by unlockOSThread (counting down by LockInternal).
 321 // Internal locks can be recursive. For instance, a lock for cgo can occur while the main
 322 // goroutine is holding the lock during the initialization phase.
 323 enum
 324 {
 325         LockExternal = 1,
 326         LockInternal = 2,
 327 };
 328
 329 struct  SigTab
 330 {
 331         int32   sig;
 332         int32   flags;
 333 };
 334 enum
 335 {
 336         SigNotify = 1<<0,       // let signal.Notify have signal, even if from kernel
 337         SigKill = 1<<1,         // if signal.Notify doesn't take it, exit quietly
 338         SigThrow = 1<<2,        // if signal.Notify doesn't take it, exit loudly
 339         SigPanic = 1<<3,        // if the signal is from the kernel, panic
 340         SigDefault = 1<<4,      // if the signal isn't explicitly requested, don't monitor it
 341         SigHandling = 1<<5,     // our signal handler is registered
 342         SigIgnored = 1<<6,      // the signal was ignored before we registered for it
 343 };
 344
 345 // Layout of in-memory per-function information prepared by linker
 346 // See http://golang.org/s/go12symtab.
 347 // Keep in sync with linker and with ../../libmach/sym.c
 348 // and with package debug/gosym.
 349 struct  Func
 350 {
 351         String  name;
 352         uintptr entry;  // entry pc
 353 };
 354
 355 #ifdef GOOS_windows
 356 enum {
 357    Windows = 1
 358 };
 359 #else
 360 enum {
 361    Windows = 0
 362 };
 363 #endif
 364 #ifdef GOOS_solaris
 365 enum {
 366    Solaris = 1
 367 };
 368 #else
 369 enum {
 370    Solaris = 0
 371 };
 372 #endif
 373
 374 struct  Timers
 375 {
 376         Lock;
 377         G       *timerproc;
 378         bool            sleeping;
 379         bool            rescheduling;
 380         Note    waitnote;
 381         Timer   **t;
 382         int32   len;
 383         int32   cap;
 384 };
 385
 386 // Package time knows the layout of this structure.
 387 // If this struct changes, adjust ../time/sleep.go:/runtimeTimer.
 388 struct  Timer
 389 {
 390         int32   i;      // heap index
 391
 392         // Timer wakes up at when, and then at when+period, ... (period > 0 only)
 393         // each time calling f(now, arg) in the timer goroutine, so f must be
 394         // a well-behaved function and not block.
 395         int64   when;
 396         int64   period;
 397         FuncVal *fv;
 398         Eface   arg;
 399 };
 400
 401 // Lock-free stack node.
 402 struct LFNode
 403 {
 404         LFNode  *next;
 405         uintptr pushcnt;
 406 };
 407
 408 // Parallel for descriptor.
 409 struct ParFor
 410 {
 411         void (*body)(ParFor*, uint32);  // executed for each element
 412         uint32 done;                    // number of idle threads
 413         uint32 nthr;                    // total number of threads
 414         uint32 nthrmax;                 // maximum number of threads
 415         uint32 thrseq;                  // thread id sequencer
 416         uint32 cnt;                     // iteration space [0, cnt)
 417         void *ctx;                      // arbitrary user context
 418         bool wait;                      // if true, wait while all threads finish processing,
 419                                         // otherwise parfor may return while other threads are still working
 420         ParForThread *thr;              // array of thread descriptors
 421         uint32 pad;                     // to align ParForThread.pos for 64-bit atomic operations
 422         // stats
 423         uint64 nsteal;
 424         uint64 nstealcnt;
 425         uint64 nprocyield;
 426         uint64 nosyield;
 427         uint64 nsleep;
 428 };
 429
 430 // Track memory allocated by code not written in Go during a cgo call,
 431 // so that the garbage collector can see them.
 432 struct CgoMal
 433 {
 434         CgoMal  *next;
 435         void    *alloc;
 436 };
 437
 438 // Holds variables parsed from GODEBUG env var.
 439 struct DebugVars
 440 {
 441         int32   allocfreetrace;
 442         int32   efence;
 443         int32   gctrace;
 444         int32   scheddetail;
 445         int32   schedtrace;
 446 };
 447
 448 extern bool runtime_precisestack;
 449
 450 /*
 451  * defined macros
 452  *    you need super-gopher-guru privilege
 453  *    to add this list.
 454  */
 455 #define nelem(x)        (sizeof(x)/sizeof((x)[0]))
 456 #define nil             ((void*)0)
 457 #define USED(v)         ((void) v)
 458 #define ROUND(x, n)     (((x)+(n)-1)&~(uintptr)((n)-1)) /* all-caps to mark as macro: it evaluates n twice */
 459
 460 byte*   runtime_startup_random_data;
 461 uint32  runtime_startup_random_data_len;
 462 void    runtime_get_random_data(byte**, int32*);
 463
 464 enum {
 465         // hashinit wants this many random bytes
 466         HashRandomBytes = 32
 467 };
 468 void    runtime_hashinit(void);
 469
 470 void    runtime_traceback(void);
 471 void    runtime_tracebackothers(G*);
 472 enum
 473 {
 474         // The maximum number of frames we print for a traceback
 475         TracebackMaxFrames = 100,
 476 };
 477
 478 /*
 479  * external data
 480  */
 481 extern  uintptr runtime_zerobase;
 482 extern  G**     runtime_allg;
 483 extern  uintptr runtime_allglen;
 484 extern  G*      runtime_lastg;
 485 extern  M*      runtime_allm;
 486 extern  P**     runtime_allp;
 487 extern  int32   runtime_gomaxprocs;
 488 extern  uint32  runtime_needextram;
 489 extern  uint32  runtime_panicking;
 490 extern  int8*   runtime_goos;
 491 extern  int32   runtime_ncpu;
 492 extern  void    (*runtime_sysargs)(int32, uint8**);
 493 extern  DebugVars       runtime_debug;
 494 extern  uintptr runtime_maxstacksize;
 495
 496 /*
 497  * common functions and data
 498  */
 499 #define runtime_strcmp(s1, s2) __builtin_strcmp((s1), (s2))
 500 #define runtime_strstr(s1, s2) __builtin_strstr((s1), (s2))
 501 intgo   runtime_findnull(const byte*);
 502 intgo   runtime_findnullw(const uint16*);
 503 void    runtime_dump(byte*, int32);
 504
 505 void    runtime_gogo(G*);
 506 struct __go_func_type;
 507 void    runtime_args(int32, byte**);
 508 void    runtime_osinit();
 509 void    runtime_goargs(void);
 510 void    runtime_goenvs(void);
 511 void    runtime_goenvs_unix(void);
 512 void    runtime_throw(const char*) __attribute__ ((noreturn));
 513 void    runtime_panicstring(const char*) __attribute__ ((noreturn));
 514 void    runtime_prints(const char*);
 515 void    runtime_printf(const char*, ...);
 516 #define runtime_mcmp(a, b, s) __builtin_memcmp((a), (b), (s))
 517 #define runtime_memmove(a, b, s) __builtin_memmove((a), (b), (s))
 518 void*   runtime_mal(uintptr);
 519 String  runtime_gostring(const byte*);
 520 String  runtime_gostringnocopy(const byte*);
 521 void    runtime_schedinit(void);
 522 void    runtime_initsig(void);
 523 void    runtime_sigenable(uint32 sig);
 524 void    runtime_sigdisable(uint32 sig);
 525 int32   runtime_gotraceback(bool *crash);
 526 void    runtime_goroutineheader(G*);
 527 void    runtime_printtrace(Location*, int32, bool);
 528 #define runtime_open(p, f, m) open((p), (f), (m))
 529 #define runtime_read(d, v, n) read((d), (v), (n))
 530 #define runtime_write(d, v, n) write((d), (v), (n))
 531 #define runtime_close(d) close(d)
 532 void    runtime_ready(G*);
 533 const byte*     runtime_getenv(const char*);
 534 int32   runtime_atoi(const byte*);
 535 void*   runtime_mstart(void*);
 536 G*      runtime_malg(int32, byte**, size_t*);
 537 void    runtime_mpreinit(M*);
 538 void    runtime_minit(void);
 539 void    runtime_unminit(void);
 540 void    runtime_needm(void);
 541 void    runtime_dropm(void);
 542 void    runtime_signalstack(byte*, int32);
 543 MCache* runtime_allocmcache(void);
 544 void    runtime_freemcache(MCache*);
 545 void    runtime_mallocinit(void);
 546 void    runtime_mprofinit(void);
 547 #define runtime_malloc(s) __go_alloc(s)
 548 #define runtime_free(p) __go_free(p)
 549 #define runtime_getcallersp(p) __builtin_frame_address(1)
 550 int32   runtime_mcount(void);
 551 int32   runtime_gcount(void);
 552 void    runtime_mcall(void(*)(G*));
 553 uint32  runtime_fastrand1(void);
 554 int32   runtime_timediv(int64, int32, int32*);
 555
 556 // atomic operations
 557 #define runtime_cas(pval, old, new) __sync_bool_compare_and_swap (pval, old, new)
 558 #define runtime_cas64(pval, old, new) __sync_bool_compare_and_swap (pval, old, new)
 559 #define runtime_casp(pval, old, new) __sync_bool_compare_and_swap (pval, old, new)
 560 // Don't confuse with XADD x86 instruction,
 561 // this one is actually 'addx', that is, add-and-fetch.
 562 #define runtime_xadd(p, v) __sync_add_and_fetch (p, v)
 563 #define runtime_xadd64(p, v) __sync_add_and_fetch (p, v)
 564 #define runtime_xchg(p, v) __atomic_exchange_n (p, v, __ATOMIC_SEQ_CST)
 565 #define runtime_xchg64(p, v) __atomic_exchange_n (p, v, __ATOMIC_SEQ_CST)
 566 #define runtime_xchgp(p, v) __atomic_exchange_n (p, v, __ATOMIC_SEQ_CST)
 567 #define runtime_atomicload(p) __atomic_load_n (p, __ATOMIC_SEQ_CST)
 568 #define runtime_atomicstore(p, v) __atomic_store_n (p, v, __ATOMIC_SEQ_CST)
 569 #define runtime_atomicstore64(p, v) __atomic_store_n (p, v, __ATOMIC_SEQ_CST)
 570 #define runtime_atomicload64(p) __atomic_load_n (p, __ATOMIC_SEQ_CST)
 571 #define runtime_atomicloadp(p) __atomic_load_n (p, __ATOMIC_SEQ_CST)
 572 #define runtime_atomicstorep(p, v) __atomic_store_n (p, v, __ATOMIC_SEQ_CST)
 573
 574 void runtime_setmg(M*, G*);
 575 void runtime_newextram(void);
 576 #define runtime_exit(s) exit(s)
 577 #define runtime_breakpoint() __builtin_trap()
 578 void    runtime_gosched(void);
 579 void    runtime_gosched0(G*);
 580 void    runtime_schedtrace(bool);
 581 void    runtime_park(bool(*)(G*, void*), void*, const char*);
 582 void    runtime_parkunlock(Lock*, const char*);
 583 void    runtime_tsleep(int64, const char*);
 584 M*      runtime_newm(void);
 585 void    runtime_goexit(void);
 586 void    runtime_entersyscall(void) __asm__ (GOSYM_PREFIX "syscall.Entersyscall");
 587 void    runtime_entersyscallblock(void);
 588 void    runtime_exitsyscall(void) __asm__ (GOSYM_PREFIX "syscall.Exitsyscall");
 589 G*      __go_go(void (*pfn)(void*), void*);
 590 void    siginit(void);
 591 bool    __go_sigsend(int32 sig);
 592 int32   runtime_callers(int32, Location*, int32);
 593 int64   runtime_nanotime(void);
 594 void    runtime_dopanic(int32) __attribute__ ((noreturn));
 595 void    runtime_startpanic(void);
 596 void    runtime_freezetheworld(void);
 597 void    runtime_unwindstack(G*, byte*);
 598 void    runtime_sigprof();
 599 void    runtime_resetcpuprofiler(int32);
 600 void    runtime_setcpuprofilerate(void(*)(uintptr*, int32), int32);
 601 void    runtime_usleep(uint32);
 602 int64   runtime_cputicks(void);
 603 int64   runtime_tickspersecond(void);
 604 void    runtime_blockevent(int64, int32);
 605 extern int64 runtime_blockprofilerate;
 606 void    runtime_addtimer(Timer*);
 607 bool    runtime_deltimer(Timer*);
 608 G*      runtime_netpoll(bool);
 609 void    runtime_netpollinit(void);
 610 int32   runtime_netpollopen(uintptr, PollDesc*);
 611 int32   runtime_netpollclose(uintptr);
 612 void    runtime_netpollready(G**, PollDesc*, int32);
 613 uintptr runtime_netpollfd(PollDesc*);
 614 void    runtime_netpollarm(uintptr, int32);
 615 void    runtime_crash(void);
 616 void    runtime_parsedebugvars(void);
 617 void    _rt0_go(void);
 618 void*   runtime_funcdata(Func*, int32);
 619 int32   runtime_setmaxthreads(int32);
 620
 621 void    runtime_stoptheworld(void);
 622 void    runtime_starttheworld(void);
 623 extern uint32 runtime_worldsema;
 624
 625 /*
 626  * mutual exclusion locks.  in the uncontended case,
 627  * as fast as spin locks (just a few user-level instructions),
 628  * but on the contention path they sleep in the kernel.
 629  * a zeroed Lock is unlocked (no need to initialize each lock).
 630  */
 631 void    runtime_lock(Lock*);
 632 void    runtime_unlock(Lock*);
 633
 634 /*
 635  * sleep and wakeup on one-time events.
 636  * before any calls to notesleep or notewakeup,
 637  * must call noteclear to initialize the Note.
 638  * then, exactly one thread can call notesleep
 639  * and exactly one thread can call notewakeup (once).
 640  * once notewakeup has been called, the notesleep
 641  * will return.  future notesleep will return immediately.
 642  * subsequent noteclear must be called only after
 643  * previous notesleep has returned, e.g. it's disallowed
 644  * to call noteclear straight after notewakeup.
 645  *
 646  * notetsleep is like notesleep but wakes up after
 647  * a given number of nanoseconds even if the event
 648  * has not yet happened.  if a goroutine uses notetsleep to
 649  * wake up early, it must wait to call noteclear until it
 650  * can be sure that no other goroutine is calling
 651  * notewakeup.
 652  *
 653  * notesleep/notetsleep are generally called on g0,
 654  * notetsleepg is similar to notetsleep but is called on user g.
 655  */
 656 void    runtime_noteclear(Note*);
 657 void    runtime_notesleep(Note*);
 658 void    runtime_notewakeup(Note*);
 659 bool    runtime_notetsleep(Note*, int64);  // false - timeout
 660 bool    runtime_notetsleepg(Note*, int64);  // false - timeout
 661
 662 /*
 663  * low-level synchronization for implementing the above
 664  */
 665 uintptr runtime_semacreate(void);
 666 int32   runtime_semasleep(int64);
 667 void    runtime_semawakeup(M*);
 668 // or
 669 void    runtime_futexsleep(uint32*, uint32, int64);
 670 void    runtime_futexwakeup(uint32*, uint32);
 671
 672 /*
 673  * Lock-free stack.
 674  * Initialize uint64 head to 0, compare with 0 to test for emptiness.
 675  * The stack does not keep pointers to nodes,
 676  * so they can be garbage collected if there are no other pointers to nodes.
 677  */
 678 void    runtime_lfstackpush(uint64 *head, LFNode *node)
 679   __asm__ (GOSYM_PREFIX "runtime.lfstackpush");
 680 LFNode* runtime_lfstackpop(uint64 *head);
 681
 682 /*
 683  * Parallel for over [0, n).
 684  * body() is executed for each iteration.
 685  * nthr - total number of worker threads.
 686  * ctx - arbitrary user context.
 687  * if wait=true, threads return from parfor() when all work is done;
 688  * otherwise, threads can return while other threads are still finishing processing.
 689  */
 690 ParFor* runtime_parforalloc(uint32 nthrmax);
 691 void    runtime_parforsetup(ParFor *desc, uint32 nthr, uint32 n, void *ctx, bool wait, void (*body)(ParFor*, uint32));
 692 void    runtime_parfordo(ParFor *desc);
 693 void    runtime_parforiters(ParFor*, uintptr, uintptr*, uintptr*);
 694
 695 /*
 696  * low level C-called
 697  */
 698 #define runtime_mmap mmap
 699 #define runtime_munmap munmap
 700 #define runtime_madvise madvise
 701 #define runtime_memclr(buf, size) __builtin_memset((buf), 0, (size))
 702 #define runtime_getcallerpc(p) __builtin_return_address(0)
 703
 704 #ifdef __rtems__
 705 void __wrap_rtems_task_variable_add(void **);
 706 #endif
 707
 708 /*
 709  * Names generated by gccgo.
 710  */
 711 #define runtime_printbool       __go_print_bool
 712 #define runtime_printfloat      __go_print_double
 713 #define runtime_printint        __go_print_int64
 714 #define runtime_printiface      __go_print_interface
 715 #define runtime_printeface      __go_print_empty_interface
 716 #define runtime_printstring     __go_print_string
 717 #define runtime_printpointer    __go_print_pointer
 718 #define runtime_printuint       __go_print_uint64
 719 #define runtime_printslice      __go_print_slice
 720 #define runtime_printcomplex    __go_print_complex
 721
 722 /*
 723  * runtime go-called
 724  */
 725 void    runtime_printbool(_Bool);
 726 void    runtime_printbyte(int8);
 727 void    runtime_printfloat(double);
 728 void    runtime_printint(int64);
 729 void    runtime_printiface(Iface);
 730 void    runtime_printeface(Eface);
 731 void    runtime_printstring(String);
 732 void    runtime_printpc(void*);
 733 void    runtime_printpointer(void*);
 734 void    runtime_printuint(uint64);
 735 void    runtime_printhex(uint64);
 736 void    runtime_printslice(Slice);
 737 void    runtime_printcomplex(complex double);
 738 void reflect_call(const struct __go_func_type *, FuncVal *, _Bool, _Bool,
 739                   void **, void **)
 740   __asm__ (GOSYM_PREFIX "reflect.call");
 741 #define runtime_panic __go_panic
 742
 743 /*
 744  * runtime c-called (but written in Go)
 745  */
 746 void    runtime_printany(Eface)
 747      __asm__ (GOSYM_PREFIX "runtime.Printany");
 748 void    runtime_newTypeAssertionError(const String*, const String*, const String*, const String*, Eface*)
 749      __asm__ (GOSYM_PREFIX "runtime.NewTypeAssertionError");
 750 void    runtime_newErrorString(String, Eface*)
 751      __asm__ (GOSYM_PREFIX "runtime.NewErrorString");
 752 void    runtime_newErrorCString(const char*, Eface*)
 753      __asm__ (GOSYM_PREFIX "runtime.NewErrorCString");
 754
 755 /*
 756  * wrapped for go users
 757  */
 758 void    runtime_semacquire(uint32 volatile *, bool);
 759 void    runtime_semrelease(uint32 volatile *);
 760 int32   runtime_gomaxprocsfunc(int32 n);
 761 void    runtime_procyield(uint32);
 762 void    runtime_osyield(void);
 763 void    runtime_lockOSThread(void);
 764 void    runtime_unlockOSThread(void);
 765 bool    runtime_lockedOSThread(void);
 766
 767 bool    runtime_showframe(String, bool);
 768 void    runtime_printcreatedby(G*);
 769
 770 uintptr runtime_memlimit(void);
 771
 772 #define ISNAN(f) __builtin_isnan(f)
 773
 774 enum
 775 {
 776         UseSpanType = 0,
 777 };
 778
 779 #define runtime_setitimer setitimer
 780
 781 void    runtime_check(void);
 782
 783 // A list of global variables that the garbage collector must scan.
 784 struct root_list {
 785         struct root_list *next;
 786         struct root {
 787                 void *decl;
 788                 size_t size;
 789         } roots[];
 790 };
 791
 792 void    __go_register_gc_roots(struct root_list*);
 793
 794 // Size of stack space allocated using Go's allocator.
 795 // This will be 0 when using split stacks, as in that case
 796 // the stacks are allocated by the splitstack library.
 797 extern uintptr runtime_stacks_sys;
 798
 799 struct backtrace_state;
 800 extern struct backtrace_state *__go_get_backtrace_state(void);
 801 extern _Bool __go_file_line(uintptr, String*, String*, intgo *);
 802 extern byte* runtime_progname();
 803 extern void runtime_main(void*);
 804 extern uint32 runtime_in_callers;
 805
 806 int32 getproccount(void);
 807
 808 #define PREFETCH(p) __builtin_prefetch(p)
 809
 810 void    __go_set_closure(void*);
 811 void*   __go_get_closure(void);
 812
 813 bool    runtime_gcwaiting(void);
 814 void    runtime_badsignal(int);
 815 Defer*  runtime_newdefer(void);
 816 void    runtime_freedefer(Defer*);