[dev.garbage] all: merge dev.cc (493ad916c3b1) into dev.garbage

[gostls13.git] / src / runtime / runtime2.go

// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package runtime

import "unsafe"

/*
 * defined constants
 */
const (
        // G status
        //
        // If you add to this list, add to the list
        // of "okay during garbage collection" status
        // in mgc0.c too.
        _Gidle            = iota // 0
        _Grunnable               // 1 runnable and on a run queue
        _Grunning                // 2
        _Gsyscall                // 3
        _Gwaiting                // 4
        _Gmoribund_unused        // 5 currently unused, but hardcoded in gdb scripts
        _Gdead                   // 6
        _Genqueue                // 7 Only the Gscanenqueue is used.
        _Gcopystack              // 8 in this state when newstack is moving the stack
        // the following encode that the GC is scanning the stack and what to do when it is done
        _Gscan = 0x1000 // atomicstatus&~Gscan = the non-scan state,
        // _Gscanidle =     _Gscan + _Gidle,      // Not used. Gidle only used with newly malloced gs
        _Gscanrunnable = _Gscan + _Grunnable //  0x1001 When scanning complets make Grunnable (it is already on run queue)
        _Gscanrunning  = _Gscan + _Grunning  //  0x1002 Used to tell preemption newstack routine to scan preempted stack.
        _Gscansyscall  = _Gscan + _Gsyscall  //  0x1003 When scanning completes make is Gsyscall
        _Gscanwaiting  = _Gscan + _Gwaiting  //  0x1004 When scanning completes make it Gwaiting
        // _Gscanmoribund_unused,               //  not possible
        // _Gscandead,                          //  not possible
        _Gscanenqueue = _Gscan + _Genqueue //  When scanning completes make it Grunnable and put on runqueue
)

const (
        // P status
        _Pidle = iota
        _Prunning
        _Psyscall
        _Pgcstop
        _Pdead
)

// The next line makes 'go generate' write the zgen_*.go files with
// per-OS and per-arch information, including constants
// named goos_$GOOS and goarch_$GOARCH for every
// known GOOS and GOARCH. The constant is 1 on the
// current system, 0 otherwise; multiplying by them is
// useful for defining GOOS- or GOARCH-specific constants.
//go:generate go run gengoos.go

type mutex struct {
        // Futex-based impl treats it as uint32 key,
        // while sema-based impl as M* waitm.
        // Used to be a union, but unions break precise GC.
        key uintptr
}

type note struct {
        // Futex-based impl treats it as uint32 key,
        // while sema-based impl as M* waitm.
        // Used to be a union, but unions break precise GC.
        key uintptr
}

type _string struct {
        str *byte
        len int
}

type funcval struct {
        fn uintptr
        // variable-size, fn-specific data here
}

type iface struct {
        tab  *itab
        data unsafe.Pointer
}

type eface struct {
        _type *_type
        data  unsafe.Pointer
}

type slice struct {
        array *byte // actual data
        len   uint  // number of elements
        cap   uint  // allocated number of elements
}

type gobuf struct {
        // The offsets of sp, pc, and g are known to (hard-coded in) libmach.
        sp   uintptr
        pc   uintptr
        g    *g
        ctxt unsafe.Pointer // this has to be a pointer so that gc scans it
        ret  uintreg
        lr   uintptr
}

// Known to compiler.
// Changes here must also be made in src/cmd/gc/select.c's selecttype.
type sudog struct {
        g           *g
        selectdone  *uint32
        next        *sudog
        prev        *sudog
        elem        unsafe.Pointer // data element
        releasetime int64
        nrelease    int32  // -1 for acquire
        waitlink    *sudog // g.waiting list
}

type gcstats struct {
        // the struct must consist of only uint64's,
        // because it is casted to uint64[].
        nhandoff    uint64
        nhandoffcnt uint64
        nprocyield  uint64
        nosyield    uint64
        nsleep      uint64
}

type libcall struct {
        fn   uintptr
        n    uintptr // number of parameters
        args uintptr // parameters
        r1   uintptr // return values
        r2   uintptr
        err  uintptr // error number
}

// describes how to handle callback
type wincallbackcontext struct {
        gobody       unsafe.Pointer // go function to call
        argsize      uintptr        // callback arguments size (in bytes)
        restorestack uintptr        // adjust stack on return by (in bytes) (386 only)
        cleanstack   bool
}

// Stack describes a Go execution stack.
// The bounds of the stack are exactly [lo, hi),
// with no implicit data structures on either side.
type stack struct {
        lo uintptr
        hi uintptr
}

type g struct {
        // Stack parameters.
        // stack describes the actual stack memory: [stack.lo, stack.hi).
        // stackguard0 is the stack pointer compared in the Go stack growth prologue.
        // It is stack.lo+StackGuard normally, but can be StackPreempt to trigger a preemption.
        // stackguard1 is the stack pointer compared in the C stack growth prologue.
        // It is stack.lo+StackGuard on g0 and gsignal stacks.
        // It is ~0 on other goroutine stacks, to trigger a call to morestackc (and crash).
        stack       stack   // offset known to runtime/cgo
        stackguard0 uintptr // offset known to liblink
        stackguard1 uintptr // offset known to liblink

        _panic       *_panic // innermost panic - offset known to liblink
        _defer       *_defer // innermost defer
        sched        gobuf
        syscallsp    uintptr        // if status==gsyscall, syscallsp = sched.sp to use during gc
        syscallpc    uintptr        // if status==gsyscall, syscallpc = sched.pc to use during gc
        param        unsafe.Pointer // passed parameter on wakeup
        atomicstatus uint32
        goid         int64
        waitsince    int64  // approx time when the g become blocked
        waitreason   string // if status==gwaiting
        schedlink    *g
        issystem     bool // do not output in stack dump, ignore in deadlock detector
        preempt      bool // preemption signal, duplicates stackguard0 = stackpreempt
        paniconfault bool // panic (instead of crash) on unexpected fault address
        preemptscan  bool // preempted g does scan for gc
        gcworkdone   bool // debug: cleared at begining of gc work phase cycle, set by gcphasework, tested at end of cycle
        throwsplit   bool // must not split stack
        raceignore   int8 // ignore race detection events
        m            *m   // for debuggers, but offset not hard-coded
        lockedm      *m
        sig          uint32
        writebuf     []byte
        sigcode0     uintptr
        sigcode1     uintptr
        sigpc        uintptr
        gopc         uintptr // pc of go statement that created this goroutine
        racectx      uintptr
        waiting      *sudog // sudog structures this g is waiting on (that have a valid elem ptr)
        end          [0]byte
}

type mts struct {
        tv_sec  int64
        tv_nsec int64
}

type mscratch struct {
        v [6]uintptr
}

type m struct {
        g0      *g    // goroutine with scheduling stack
        morebuf gobuf // gobuf arg to morestack

        // Fields not known to debuggers.
        procid        uint64         // for debuggers, but offset not hard-coded
        gsignal       *g             // signal-handling g
        tls           [4]uintptr     // thread-local storage (for x86 extern register)
        mstartfn      unsafe.Pointer // todo go func()
        curg          *g             // current running goroutine
        caughtsig     *g             // goroutine running during fatal signal
        p             *p             // attached p for executing go code (nil if not executing go code)
        nextp         *p
        id            int32
        mallocing     int32
        throwing      int32
        gcing         int32
        locks         int32
        softfloat     int32
        dying         int32
        profilehz     int32
        helpgc        int32
        spinning      bool // m is out of work and is actively looking for work
        blocked       bool // m is blocked on a note
        inwb          bool // m is executing a write barrier
        printlock     int8
        fastrand      uint32
        ncgocall      uint64 // number of cgo calls in total
        ncgo          int32  // number of cgo calls currently in progress
        cgomal        *cgomal
        park          note
        alllink       *m // on allm
        schedlink     *m
        machport      uint32 // return address for mach ipc (os x)
        mcache        *mcache
        lockedg       *g
        createstack   [32]uintptr // stack that created this thread.
        freglo        [16]uint32  // d[i] lsb and f[i]
        freghi        [16]uint32  // d[i] msb and f[i+16]
        fflag         uint32      // floating point compare flags
        locked        uint32      // tracking for lockosthread
        nextwaitm     *m          // next m waiting for lock
        waitsema      uintptr     // semaphore for parking on locks
        waitsemacount uint32
        waitsemalock  uint32
        gcstats       gcstats
        needextram    bool
        traceback     uint8
        waitunlockf   unsafe.Pointer // todo go func(*g, unsafe.pointer) bool
        waitlock      unsafe.Pointer
        //#ifdef GOOS_windows
        thread uintptr // thread handle
        // these are here because they are too large to be on the stack
        // of low-level NOSPLIT functions.
        libcall   libcall
        libcallpc uintptr // for cpu profiler
        libcallsp uintptr
        libcallg  *g
        //#endif
        //#ifdef GOOS_solaris
        perrno *int32 // pointer to tls errno
        // these are here because they are too large to be on the stack
        // of low-level NOSPLIT functions.
        //LibCall       libcall;
        ts      mts
        scratch mscratch
        //#endif
        //#ifdef GOOS_plan9
        notesig *int8
        errstr  *byte
        //#endif
        end [0]byte
}

type p struct {
        lock mutex

        id          int32
        status      uint32 // one of pidle/prunning/...
        link        *p
        schedtick   uint32 // incremented on every scheduler call
        syscalltick uint32 // incremented on every system call
        m           *m     // back-link to associated m (nil if idle)
        mcache      *mcache
        deferpool   [5]*_defer // pool of available defer structs of different sizes (see panic.c)

        // Cache of goroutine ids, amortizes accesses to runtime·sched.goidgen.
        goidcache    uint64
        goidcacheend uint64

        // Queue of runnable goroutines.
        runqhead uint32
        runqtail uint32
        runq     [256]*g

        // Available G's (status == Gdead)
        gfree    *g
        gfreecnt int32

        pad [64]byte
}

const (
        // The max value of GOMAXPROCS.
        // There are no fundamental restrictions on the value.
        _MaxGomaxprocs = 1 << 8
)

type schedt struct {
        lock mutex

        goidgen uint64

        midle        *m    // idle m's waiting for work
        nmidle       int32 // number of idle m's waiting for work
        nmidlelocked int32 // number of locked m's waiting for work
        mcount       int32 // number of m's that have been created
        maxmcount    int32 // maximum number of m's allowed (or die)

        pidle      *p // idle p's
        npidle     uint32
        nmspinning uint32

        // Global runnable queue.
        runqhead *g
        runqtail *g
        runqsize int32

        // Global cache of dead G's.
        gflock mutex
        gfree  *g
        ngfree int32

        gcwaiting  uint32 // gc is waiting to run
        stopwait   int32
        stopnote   note
        sysmonwait uint32
        sysmonnote note
        lastpoll   uint64

        profilehz int32 // cpu profiling rate
}

// The m->locked word holds two pieces of state counting active calls to LockOSThread/lockOSThread.
// The low bit (LockExternal) is a boolean reporting whether any LockOSThread call is active.
// External locks are not recursive; a second lock is silently ignored.
// The upper bits of m->lockedcount record the nesting depth of calls to lockOSThread
// (counting up by LockInternal), popped by unlockOSThread (counting down by LockInternal).
// Internal locks can be recursive. For instance, a lock for cgo can occur while the main
// goroutine is holding the lock during the initialization phase.
const (
        _LockExternal = 1
        _LockInternal = 2
)

type sigtabtt struct {
        flags int32
        name  *int8
}

const (
        _SigNotify   = 1 << 0 // let signal.Notify have signal, even if from kernel
        _SigKill     = 1 << 1 // if signal.Notify doesn't take it, exit quietly
        _SigThrow    = 1 << 2 // if signal.Notify doesn't take it, exit loudly
        _SigPanic    = 1 << 3 // if the signal is from the kernel, panic
        _SigDefault  = 1 << 4 // if the signal isn't explicitly requested, don't monitor it
        _SigHandling = 1 << 5 // our signal handler is registered
        _SigIgnored  = 1 << 6 // the signal was ignored before we registered for it
        _SigGoExit   = 1 << 7 // cause all runtime procs to exit (only used on Plan 9).
)

// Layout of in-memory per-function information prepared by linker
// See http://golang.org/s/go12symtab.
// Keep in sync with linker and with ../../libmach/sym.c
// and with package debug/gosym and with symtab.go in package runtime.
type _func struct {
        entry   uintptr // start pc
        nameoff int32   // function name

        args  int32 // in/out args size
        frame int32 // legacy frame size; use pcsp if possible

        pcsp      int32
        pcfile    int32
        pcln      int32
        npcdata   int32
        nfuncdata int32
}

// layout of Itab known to compilers
// allocated in non-garbage-collected memory
type itab struct {
        inter  *interfacetype
        _type  *_type
        link   *itab
        bad    int32
        unused int32
        fun    [0]uintptr
}

// Lock-free stack node.
// // Also known to export_test.go.
type lfnode struct {
        next    uint64
        pushcnt uintptr
}

// Parallel for descriptor.
type parfor struct {
        body    unsafe.Pointer // go func(*parfor, uint32), executed for each element
        done    uint32         // number of idle threads
        nthr    uint32         // total number of threads
        nthrmax uint32         // maximum number of threads
        thrseq  uint32         // thread id sequencer
        cnt     uint32         // iteration space [0, cnt)
        ctx     unsafe.Pointer // arbitrary user context
        wait    bool           // if true, wait while all threads finish processing,
        // otherwise parfor may return while other threads are still working
        thr *parforthread // array of thread descriptors
        pad uint32        // to align parforthread.pos for 64-bit atomic operations
        // stats
        nsteal     uint64
        nstealcnt  uint64
        nprocyield uint64
        nosyield   uint64
        nsleep     uint64
}

// Track memory allocated by code not written in Go during a cgo call,
// so that the garbage collector can see them.
type cgomal struct {
        next  *cgomal
        alloc unsafe.Pointer
}

// Holds variables parsed from GODEBUG env var.
type debugvars struct {
        allocfreetrace int32
        efence         int32
        gctrace        int32
        gcdead         int32
        scheddetail    int32
        schedtrace     int32
        scavenge       int32
}

// Indicates to write barrier and sychronization task to preform.
const (
        _GCoff             = iota // GC not running, write barrier disabled
        _GCquiesce                // unused state
        _GCstw                    // unused state
        _GCscan                   // GC collecting roots into workbufs, write barrier disabled
        _GCmark                   // GC marking from workbufs, write barrier ENABLED
        _GCmarktermination        // GC mark termination: allocate black, P's help GC, write barrier ENABLED
        _GCsweep                  // GC mark completed; sweeping in background, write barrier disabled
)

type forcegcstate struct {
        lock mutex
        g    *g
        idle uint32
}

var gcphase uint32

/*
 * known to compiler
 */
const (
        _Structrnd = regSize
)

var startup_random_data *byte
var startup_random_data_len uint32

var invalidptr int32

const (
        // hashinit wants this many random bytes
        _HashRandomBytes = 32
)

/*
 * deferred subroutine calls
 */
type _defer struct {
        siz     int32
        started bool
        argp    uintptr // where args were copied from
        pc      uintptr
        fn      *funcval
        _panic  *_panic // panic that is running defer
        link    *_defer
}

/*
 * panics
 */
type _panic struct {
        argp      unsafe.Pointer // pointer to arguments of deferred call run during panic; cannot move - known to liblink
        arg       interface{}    // argument to panic
        link      *_panic        // link to earlier panic
        recovered bool           // whether this panic is over
        aborted   bool           // the panic was aborted
}

/*
 * stack traces
 */

type stkframe struct {
        fn       *_func     // function being run
        pc       uintptr    // program counter within fn
        continpc uintptr    // program counter where execution can continue, or 0 if not
        lr       uintptr    // program counter at caller aka link register
        sp       uintptr    // stack pointer at pc
        fp       uintptr    // stack pointer at caller aka frame pointer
        varp     uintptr    // top of local variables
        argp     uintptr    // pointer to function arguments
        arglen   uintptr    // number of bytes at argp
        argmap   *bitvector // force use of this argmap
}

const (
        _TraceRuntimeFrames = 1 << 0 // include frames for internal runtime functions.
        _TraceTrap          = 1 << 1 // the initial PC, SP are from a trap, not a return PC from a call
)

const (
        // The maximum number of frames we print for a traceback
        _TracebackMaxFrames = 100
)

var (
        emptystring string
        allg        **g
        allglen     uintptr
        lastg       *g
        allm        *m
        allp        [_MaxGomaxprocs + 1]*p
        gomaxprocs  int32
        needextram  uint32
        panicking   uint32
        goos        *int8
        ncpu        int32
        iscgo       bool
        cpuid_ecx   uint32
        cpuid_edx   uint32
        debug       debugvars
        signote     note
        forcegc     forcegcstate
        sched       schedt
        newprocs    int32
)

/*
 * mutual exclusion locks.  in the uncontended case,
 * as fast as spin locks (just a few user-level instructions),
 * but on the contention path they sleep in the kernel.
 * a zeroed Mutex is unlocked (no need to initialize each lock).
 */

/*
 * sleep and wakeup on one-time events.
 * before any calls to notesleep or notewakeup,
 * must call noteclear to initialize the Note.
 * then, exactly one thread can call notesleep
 * and exactly one thread can call notewakeup (once).
 * once notewakeup has been called, the notesleep
 * will return.  future notesleep will return immediately.
 * subsequent noteclear must be called only after
 * previous notesleep has returned, e.g. it's disallowed
 * to call noteclear straight after notewakeup.
 *
 * notetsleep is like notesleep but wakes up after
 * a given number of nanoseconds even if the event
 * has not yet happened.  if a goroutine uses notetsleep to
 * wake up early, it must wait to call noteclear until it
 * can be sure that no other goroutine is calling
 * notewakeup.
 *
 * notesleep/notetsleep are generally called on g0,
 * notetsleepg is similar to notetsleep but is called on user g.
 */
// bool runtime·notetsleep(Note*, int64);  // false - timeout
// bool runtime·notetsleepg(Note*, int64);  // false - timeout

/*
 * Lock-free stack.
 * Initialize uint64 head to 0, compare with 0 to test for emptiness.
 * The stack does not keep pointers to nodes,
 * so they can be garbage collected if there are no other pointers to nodes.
 */

/*
 * Parallel for over [0, n).
 * body() is executed for each iteration.
 * nthr - total number of worker threads.
 * ctx - arbitrary user context.
 * if wait=true, threads return from parfor() when all work is done;
 * otherwise, threads can return while other threads are still finishing processing.
 */

// for mmap, we only pass the lower 32 bits of file offset to the
// assembly routine; the higher bits (if required), should be provided
// by the assembly routine as 0.