blob: db6072b5ce719bcaf54c99f5c13902c2d2548cbc [file] [log] [blame]
// 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.
#include "runtime.h"
#include "arch.h"
#include "defs.h"
#include "malloc.h"
#include "os.h"
#include "stack.h"
bool runtime·iscgo;
static void unwindstack(G*, byte*);
typedef struct Sched Sched;
M runtime·m0;
G runtime·g0; // idle goroutine for m0
static int32 debug = 0;
int32 runtime·gcwaiting;
// Go scheduler
//
// The go scheduler's job is to match ready-to-run goroutines (`g's)
// with waiting-for-work schedulers (`m's). If there are ready gs
// and no waiting ms, ready() will start a new m running in a new
// OS thread, so that all ready gs can run simultaneously, up to a limit.
// For now, ms never go away.
//
// By default, Go keeps only one kernel thread (m) running user code
// at a single time; other threads may be blocked in the operating system.
// Setting the environment variable $GOMAXPROCS or calling
// runtime.GOMAXPROCS() will change the number of user threads
// allowed to execute simultaneously. $GOMAXPROCS is thus an
// approximation of the maximum number of cores to use.
//
// Even a program that can run without deadlock in a single process
// might use more ms if given the chance. For example, the prime
// sieve will use as many ms as there are primes (up to runtime·sched.mmax),
// allowing different stages of the pipeline to execute in parallel.
// We could revisit this choice, only kicking off new ms for blocking
// system calls, but that would limit the amount of parallel computation
// that go would try to do.
//
// In general, one could imagine all sorts of refinements to the
// scheduler, but the goal now is just to get something working on
// Linux and OS X.
struct Sched {
Lock;
G *gfree; // available gs (status == Gdead)
G *ghead; // gs waiting to run
G *gtail;
int32 gwait; // number of gs waiting to run
int32 gcount; // number of gs that are alive
M *mhead; // ms waiting for work
int32 mwait; // number of ms waiting for work
int32 mcount; // number of ms that have been created
int32 mcpu; // number of ms executing on cpu
int32 mcpumax; // max number of ms allowed on cpu
int32 msyscall; // number of ms in system calls
int32 predawn; // running initialization, don't run new gs.
Note stopped; // one g can wait here for ms to stop
int32 waitstop; // after setting this flag
};
Sched runtime·sched;
int32 gomaxprocs;
// Scheduling helpers. Sched must be locked.
static void gput(G*); // put/get on ghead/gtail
static G* gget(void);
static void mput(M*); // put/get on mhead
static M* mget(G*);
static void gfput(G*); // put/get on gfree
static G* gfget(void);
static void matchmg(void); // match ms to gs
static void readylocked(G*); // ready, but sched is locked
static void mnextg(M*, G*);
// Scheduler loop.
static void scheduler(void);
// The bootstrap sequence is:
//
// call osinit
// call schedinit
// make & queue new G
// call runtime·mstart
//
// The new G does:
//
// call main·init_function
// call initdone
// call main·main
void
runtime·schedinit(void)
{
int32 n;
byte *p;
runtime·allm = m;
m->nomemprof++;
runtime·mallocinit();
runtime·goargs();
runtime·goenvs();
// For debugging:
// Allocate internal symbol table representation now,
// so that we don't need to call malloc when we crash.
// runtime·findfunc(0);
runtime·gomaxprocs = 1;
p = runtime·getenv("GOMAXPROCS");
if(p != nil && (n = runtime·atoi(p)) != 0)
runtime·gomaxprocs = n;
runtime·sched.mcpumax = runtime·gomaxprocs;
runtime·sched.mcount = 1;
runtime·sched.predawn = 1;
m->nomemprof--;
}
// Called after main·init_function; main·main will be called on return.
void
runtime·initdone(void)
{
// Let's go.
runtime·sched.predawn = 0;
mstats.enablegc = 1;
// If main·init_function started other goroutines,
// kick off new ms to handle them, like ready
// would have, had it not been pre-dawn.
runtime·lock(&runtime·sched);
matchmg();
runtime·unlock(&runtime·sched);
}
void
runtime·goexit(void)
{
g->status = Gmoribund;
runtime·gosched();
}
void
runtime·tracebackothers(G *me)
{
G *g;
for(g = runtime·allg; g != nil; g = g->alllink) {
if(g == me || g->status == Gdead)
continue;
runtime·printf("\ngoroutine %d [%d]:\n", g->goid, g->status);
runtime·traceback(g->sched.pc, g->sched.sp, 0, g);
}
}
// Mark this g as m's idle goroutine.
// This functionality might be used in environments where programs
// are limited to a single thread, to simulate a select-driven
// network server. It is not exposed via the standard runtime API.
void
runtime·idlegoroutine(void)
{
if(g->idlem != nil)
runtime·throw("g is already an idle goroutine");
g->idlem = m;
}
// Put on `g' queue. Sched must be locked.
static void
gput(G *g)
{
M *m;
// If g is wired, hand it off directly.
if(runtime·sched.mcpu < runtime·sched.mcpumax && (m = g->lockedm) != nil) {
mnextg(m, g);
return;
}
// If g is the idle goroutine for an m, hand it off.
if(g->idlem != nil) {
if(g->idlem->idleg != nil) {
runtime·printf("m%d idle out of sync: g%d g%d\n",
g->idlem->id,
g->idlem->idleg->goid, g->goid);
runtime·throw("runtime: double idle");
}
g->idlem->idleg = g;
return;
}
g->schedlink = nil;
if(runtime·sched.ghead == nil)
runtime·sched.ghead = g;
else
runtime·sched.gtail->schedlink = g;
runtime·sched.gtail = g;
runtime·sched.gwait++;
}
// Get from `g' queue. Sched must be locked.
static G*
gget(void)
{
G *g;
g = runtime·sched.ghead;
if(g){
runtime·sched.ghead = g->schedlink;
if(runtime·sched.ghead == nil)
runtime·sched.gtail = nil;
runtime·sched.gwait--;
} else if(m->idleg != nil) {
g = m->idleg;
m->idleg = nil;
}
return g;
}
// Put on `m' list. Sched must be locked.
static void
mput(M *m)
{
m->schedlink = runtime·sched.mhead;
runtime·sched.mhead = m;
runtime·sched.mwait++;
}
// Get an `m' to run `g'. Sched must be locked.
static M*
mget(G *g)
{
M *m;
// if g has its own m, use it.
if((m = g->lockedm) != nil)
return m;
// otherwise use general m pool.
if((m = runtime·sched.mhead) != nil){
runtime·sched.mhead = m->schedlink;
runtime·sched.mwait--;
}
return m;
}
// Mark g ready to run.
void
runtime·ready(G *g)
{
runtime·lock(&runtime·sched);
readylocked(g);
runtime·unlock(&runtime·sched);
}
// Mark g ready to run. Sched is already locked.
// G might be running already and about to stop.
// The sched lock protects g->status from changing underfoot.
static void
readylocked(G *g)
{
if(g->m){
// Running on another machine.
// Ready it when it stops.
g->readyonstop = 1;
return;
}
// Mark runnable.
if(g->status == Grunnable || g->status == Grunning || g->status == Grecovery || g->status == Gstackalloc) {
runtime·printf("goroutine %d has status %d\n", g->goid, g->status);
runtime·throw("bad g->status in ready");
}
g->status = Grunnable;
gput(g);
if(!runtime·sched.predawn)
matchmg();
}
static void
nop(void)
{
}
// Same as readylocked but a different symbol so that
// debuggers can set a breakpoint here and catch all
// new goroutines.
static void
newprocreadylocked(G *g)
{
nop(); // avoid inlining in 6l
readylocked(g);
}
// Pass g to m for running.
static void
mnextg(M *m, G *g)
{
runtime·sched.mcpu++;
m->nextg = g;
if(m->waitnextg) {
m->waitnextg = 0;
runtime·notewakeup(&m->havenextg);
}
}
// Get the next goroutine that m should run.
// Sched must be locked on entry, is unlocked on exit.
// Makes sure that at most $GOMAXPROCS gs are
// running on cpus (not in system calls) at any given time.
static G*
nextgandunlock(void)
{
G *gp;
if(runtime·sched.mcpu < 0)
runtime·throw("negative runtime·sched.mcpu");
// If there is a g waiting as m->nextg,
// mnextg took care of the runtime·sched.mcpu++.
if(m->nextg != nil) {
gp = m->nextg;
m->nextg = nil;
runtime·unlock(&runtime·sched);
return gp;
}
if(m->lockedg != nil) {
// We can only run one g, and it's not available.
// Make sure some other cpu is running to handle
// the ordinary run queue.
if(runtime·sched.gwait != 0)
matchmg();
} else {
// Look for work on global queue.
while(runtime·sched.mcpu < runtime·sched.mcpumax && (gp=gget()) != nil) {
if(gp->lockedm) {
mnextg(gp->lockedm, gp);
continue;
}
runtime·sched.mcpu++; // this m will run gp
runtime·unlock(&runtime·sched);
return gp;
}
// Otherwise, wait on global m queue.
mput(m);
}
if(runtime·sched.mcpu == 0 && runtime·sched.msyscall == 0)
runtime·throw("all goroutines are asleep - deadlock!");
m->nextg = nil;
m->waitnextg = 1;
runtime·noteclear(&m->havenextg);
if(runtime·sched.waitstop && runtime·sched.mcpu <= runtime·sched.mcpumax) {
runtime·sched.waitstop = 0;
runtime·notewakeup(&runtime·sched.stopped);
}
runtime·unlock(&runtime·sched);
runtime·notesleep(&m->havenextg);
if((gp = m->nextg) == nil)
runtime·throw("bad m->nextg in nextgoroutine");
m->nextg = nil;
return gp;
}
// TODO(rsc): Remove. This is only temporary,
// for the mark and sweep collector.
void
runtime·stoptheworld(void)
{
runtime·lock(&runtime·sched);
runtime·gcwaiting = 1;
runtime·sched.mcpumax = 1;
while(runtime·sched.mcpu > 1) {
// It would be unsafe for multiple threads to be using
// the stopped note at once, but there is only
// ever one thread doing garbage collection,
// so this is okay.
runtime·noteclear(&runtime·sched.stopped);
runtime·sched.waitstop = 1;
runtime·unlock(&runtime·sched);
runtime·notesleep(&runtime·sched.stopped);
runtime·lock(&runtime·sched);
}
runtime·unlock(&runtime·sched);
}
// TODO(rsc): Remove. This is only temporary,
// for the mark and sweep collector.
void
runtime·starttheworld(void)
{
runtime·lock(&runtime·sched);
runtime·gcwaiting = 0;
runtime·sched.mcpumax = runtime·gomaxprocs;
matchmg();
runtime·unlock(&runtime·sched);
}
// Called to start an M.
void
runtime·mstart(void)
{
if(g != m->g0)
runtime·throw("bad runtime·mstart");
if(m->mcache == nil)
m->mcache = runtime·allocmcache();
runtime·minit();
scheduler();
}
// When running with cgo, we call libcgo_thread_start
// to start threads for us so that we can play nicely with
// foreign code.
void (*libcgo_thread_start)(void*);
typedef struct CgoThreadStart CgoThreadStart;
struct CgoThreadStart
{
M *m;
G *g;
void (*fn)(void);
};
// Kick off new ms as needed (up to mcpumax).
// There are already `other' other cpus that will
// start looking for goroutines shortly.
// Sched is locked.
static void
matchmg(void)
{
G *g;
if(m->mallocing || m->gcing)
return;
while(runtime·sched.mcpu < runtime·sched.mcpumax && (g = gget()) != nil){
M *m;
// Find the m that will run g.
if((m = mget(g)) == nil){
m = runtime·malloc(sizeof(M));
// Add to runtime·allm so garbage collector doesn't free m
// when it is just in a register (R14 on amd64).
m->alllink = runtime·allm;
runtime·allm = m;
m->id = runtime·sched.mcount++;
if(runtime·iscgo) {
CgoThreadStart ts;
if(libcgo_thread_start == nil)
runtime·throw("libcgo_thread_start missing");
// pthread_create will make us a stack.
m->g0 = runtime·malg(-1);
ts.m = m;
ts.g = m->g0;
ts.fn = runtime·mstart;
runtime·runcgo(libcgo_thread_start, &ts);
} else {
if(Windows)
// windows will layout sched stack on os stack
m->g0 = runtime·malg(-1);
else
m->g0 = runtime·malg(8192);
runtime·newosproc(m, m->g0, m->g0->stackbase, runtime·mstart);
}
}
mnextg(m, g);
}
}
// Scheduler loop: find g to run, run it, repeat.
static void
scheduler(void)
{
G* gp;
runtime·lock(&runtime·sched);
if(runtime·gosave(&m->sched) != 0){
gp = m->curg;
if(gp->status == Grecovery) {
// switched to scheduler to get stack unwound.
// don't go through the full scheduling logic.
Defer *d;
d = gp->defer;
gp->defer = d->link;
// unwind to the stack frame with d's arguments in it.
unwindstack(gp, d->argp);
// make the deferproc for this d return again,
// this time returning 1. function will jump to
// standard return epilogue.
// the -2*sizeof(uintptr) makes up for the
// two extra words that are on the stack at
// each call to deferproc.
// (the pc we're returning to does pop pop
// before it tests the return value.)
// on the arm there are 2 saved LRs mixed in too.
if(thechar == '5')
gp->sched.sp = (byte*)d->argp - 4*sizeof(uintptr);
else
gp->sched.sp = (byte*)d->argp - 2*sizeof(uintptr);
gp->sched.pc = d->pc;
gp->status = Grunning;
runtime·free(d);
runtime·gogo(&gp->sched, 1);
}
if(gp->status == Gstackalloc) {
// switched to scheduler stack to call stackalloc.
gp->param = runtime·stackalloc((uintptr)gp->param);
gp->status = Grunning;
runtime·gogo(&gp->sched, 1);
}
// Jumped here via runtime·gosave/gogo, so didn't
// execute lock(&runtime·sched) above.
runtime·lock(&runtime·sched);
if(runtime·sched.predawn)
runtime·throw("init sleeping");
// Just finished running gp.
gp->m = nil;
runtime·sched.mcpu--;
if(runtime·sched.mcpu < 0)
runtime·throw("runtime·sched.mcpu < 0 in scheduler");
switch(gp->status){
case Grunnable:
case Gdead:
case Grecovery:
case Gstackalloc:
// Shouldn't have been running!
runtime·throw("bad gp->status in sched");
case Grunning:
gp->status = Grunnable;
gput(gp);
break;
case Gmoribund:
gp->status = Gdead;
if(gp->lockedm) {
gp->lockedm = nil;
m->lockedg = nil;
}
gp->idlem = nil;
unwindstack(gp, nil);
gfput(gp);
if(--runtime·sched.gcount == 0)
runtime·exit(0);
break;
}
if(gp->readyonstop){
gp->readyonstop = 0;
readylocked(gp);
}
}
// Find (or wait for) g to run. Unlocks runtime·sched.
gp = nextgandunlock();
gp->readyonstop = 0;
gp->status = Grunning;
m->curg = gp;
gp->m = m;
if(gp->sched.pc == (byte*)runtime·goexit) { // kickoff
runtime·gogocall(&gp->sched, (void(*)(void))gp->entry);
}
runtime·gogo(&gp->sched, 1);
}
// Enter scheduler. If g->status is Grunning,
// re-queues g and runs everyone else who is waiting
// before running g again. If g->status is Gmoribund,
// kills off g.
void
runtime·gosched(void)
{
if(m->locks != 0)
runtime·throw("gosched holding locks");
if(g == m->g0)
runtime·throw("gosched of g0");
if(runtime·gosave(&g->sched) == 0)
runtime·gogo(&m->sched, 1);
}
// The goroutine g is about to enter a system call.
// Record that it's not using the cpu anymore.
// This is called only from the go syscall library and cgocall,
// not from the low-level system calls used by the runtime.
// Entersyscall cannot split the stack: the runtime·gosave must
// make g->sched refer to the caller's stack pointer.
#pragma textflag 7
void
runtime·entersyscall(void)
{
runtime·lock(&runtime·sched);
// Leave SP around for gc and traceback.
// Do before notewakeup so that gc
// never sees Gsyscall with wrong stack.
runtime·gosave(&g->sched);
if(runtime·sched.predawn) {
runtime·unlock(&runtime·sched);
return;
}
g->status = Gsyscall;
runtime·sched.mcpu--;
runtime·sched.msyscall++;
if(runtime·sched.gwait != 0)
matchmg();
if(runtime·sched.waitstop && runtime·sched.mcpu <= runtime·sched.mcpumax) {
runtime·sched.waitstop = 0;
runtime·notewakeup(&runtime·sched.stopped);
}
runtime·unlock(&runtime·sched);
}
// The goroutine g exited its system call.
// Arrange for it to run on a cpu again.
// This is called only from the go syscall library, not
// from the low-level system calls used by the runtime.
void
runtime·exitsyscall(void)
{
runtime·lock(&runtime·sched);
if(runtime·sched.predawn) {
runtime·unlock(&runtime·sched);
return;
}
runtime·sched.msyscall--;
runtime·sched.mcpu++;
// Fast path - if there's room for this m, we're done.
if(runtime·sched.mcpu <= runtime·sched.mcpumax) {
g->status = Grunning;
runtime·unlock(&runtime·sched);
return;
}
// Tell scheduler to put g back on the run queue:
// mostly equivalent to g->status = Grunning,
// but keeps the garbage collector from thinking
// that g is running right now, which it's not.
g->readyonstop = 1;
runtime·unlock(&runtime·sched);
// Slow path - all the cpus are taken.
// The scheduler will ready g and put this m to sleep.
// When the scheduler takes g away from m,
// it will undo the runtime·sched.mcpu++ above.
runtime·gosched();
}
// Restore the position of m's scheduler stack if we unwind the stack
// through a cgo callback.
static void
runtime·unwindcgocallback(void **spaddr, void *sp)
{
*spaddr = sp;
}
// Start scheduling g1 again for a cgo callback.
void
runtime·startcgocallback(G* g1)
{
Defer *d;
runtime·lock(&runtime·sched);
g1->status = Grunning;
runtime·sched.msyscall--;
runtime·sched.mcpu++;
runtime·unlock(&runtime·sched);
// Add an entry to the defer stack which restores the old
// position of m's scheduler stack. This is so that if the
// code we are calling panics, we won't lose the space on the
// scheduler stack. Note that we are locked to this m here.
d = runtime·malloc(sizeof(*d) + 2*sizeof(void*) - sizeof(d->args));
d->fn = (byte*)runtime·unwindcgocallback;
d->siz = 2 * sizeof(uintptr);
((void**)d->args)[0] = &m->sched.sp;
((void**)d->args)[1] = m->sched.sp;
d->link = g1->defer;
g1->defer = d;
}
// Stop scheduling g1 after a cgo callback.
void
runtime·endcgocallback(G* g1)
{
Defer *d;
runtime·lock(&runtime·sched);
g1->status = Gsyscall;
runtime·sched.mcpu--;
runtime·sched.msyscall++;
runtime·unlock(&runtime·sched);
// Remove the entry on the defer stack added by
// startcgocallback.
d = g1->defer;
if (d == nil || d->fn != (byte*)runtime·unwindcgocallback)
runtime·throw("bad defer entry in endcgocallback");
g1->defer = d->link;
runtime·free(d);
}
void
runtime·oldstack(void)
{
Stktop *top, old;
uint32 argsize;
byte *sp;
G *g1;
static int32 goid;
//printf("oldstack m->cret=%p\n", m->cret);
g1 = m->curg;
top = (Stktop*)g1->stackbase;
sp = (byte*)top;
old = *top;
argsize = old.argsize;
if(argsize > 0) {
sp -= argsize;
runtime·mcpy(top->argp, sp, argsize);
}
goid = old.gobuf.g->goid; // fault if g is bad, before gogo
if(old.free != 0)
runtime·stackfree(g1->stackguard - StackGuard - StackSystem, old.free);
g1->stackbase = old.stackbase;
g1->stackguard = old.stackguard;
runtime·gogo(&old.gobuf, m->cret);
}
void
runtime·newstack(void)
{
int32 framesize, argsize;
Stktop *top;
byte *stk, *sp;
G *g1;
Gobuf label;
bool reflectcall;
uintptr free;
framesize = m->moreframesize;
argsize = m->moreargsize;
g1 = m->curg;
if(m->morebuf.sp < g1->stackguard - StackGuard) {
runtime·printf("runtime: split stack overflow: %p < %p\n", m->morebuf.sp, g1->stackguard - StackGuard);
runtime·throw("runtime: split stack overflow");
}
reflectcall = framesize==1;
if(reflectcall)
framesize = 0;
if(reflectcall && m->morebuf.sp - sizeof(Stktop) - argsize - 32 > g1->stackguard) {
// special case: called from reflect.call (framesize==1)
// to call code with an arbitrary argument size,
// and we have enough space on the current stack.
// the new Stktop* is necessary to unwind, but
// we don't need to create a new segment.
top = (Stktop*)(m->morebuf.sp - sizeof(*top));
stk = g1->stackguard - StackGuard - StackSystem;
free = 0;
} else {
// allocate new segment.
framesize += argsize;
framesize += StackExtra; // room for more functions, Stktop.
if(framesize < StackMin)
framesize = StackMin;
framesize += StackSystem;
stk = runtime·stackalloc(framesize);
top = (Stktop*)(stk+framesize-sizeof(*top));
free = framesize;
}
//runtime·printf("newstack framesize=%d argsize=%d morepc=%p moreargp=%p gobuf=%p, %p top=%p old=%p\n",
//framesize, argsize, m->morepc, m->moreargp, m->morebuf.pc, m->morebuf.sp, top, g1->stackbase);
top->stackbase = g1->stackbase;
top->stackguard = g1->stackguard;
top->gobuf = m->morebuf;
top->argp = m->moreargp;
top->argsize = argsize;
top->free = free;
// copy flag from panic
top->panic = g1->ispanic;
g1->ispanic = false;
g1->stackbase = (byte*)top;
g1->stackguard = stk + StackGuard + StackSystem;
sp = (byte*)top;
if(argsize > 0) {
sp -= argsize;
runtime·mcpy(sp, m->moreargp, argsize);
}
if(thechar == '5') {
// caller would have saved its LR below args.
sp -= sizeof(void*);
*(void**)sp = nil;
}
// Continue as if lessstack had just called m->morepc
// (the PC that decided to grow the stack).
label.sp = sp;
label.pc = (byte*)runtime·lessstack;
label.g = m->curg;
runtime·gogocall(&label, m->morepc);
*(int32*)345 = 123; // never return
}
G*
runtime·malg(int32 stacksize)
{
G *newg;
byte *stk;
int32 oldstatus;
newg = runtime·malloc(sizeof(G));
if(stacksize >= 0) {
if(g == m->g0) {
// running on scheduler stack already.
stk = runtime·stackalloc(StackSystem + stacksize);
} else {
// have to call stackalloc on scheduler stack.
oldstatus = g->status;
g->param = (void*)(StackSystem + stacksize);
g->status = Gstackalloc;
// next two lines are runtime·gosched without the check
// of m->locks. we're almost certainly holding a lock,
// but this is not a real rescheduling so it's okay.
if(runtime·gosave(&g->sched) == 0)
runtime·gogo(&m->sched, 1);
stk = g->param;
g->param = nil;
g->status = oldstatus;
}
newg->stack0 = stk;
newg->stackguard = stk + StackSystem + StackGuard;
newg->stackbase = stk + StackSystem + stacksize - sizeof(Stktop);
runtime·memclr(newg->stackbase, sizeof(Stktop));
}
return newg;
}
/*
* Newproc and deferproc need to be textflag 7
* (no possible stack split when nearing overflow)
* because they assume that the arguments to fn
* are available sequentially beginning at &arg0.
* If a stack split happened, only the one word
* arg0 would be copied. It's okay if any functions
* they call split the stack below the newproc frame.
*/
#pragma textflag 7
void
runtime·newproc(int32 siz, byte* fn, ...)
{
byte *argp;
if(thechar == '5')
argp = (byte*)(&fn+2); // skip caller's saved LR
else
argp = (byte*)(&fn+1);
runtime·newproc1(fn, argp, siz, 0, runtime·getcallerpc(&siz));
}
G*
runtime·newproc1(byte *fn, byte *argp, int32 narg, int32 nret, void *callerpc)
{
byte *sp;
G *newg;
int32 siz;
//printf("newproc1 %p %p narg=%d nret=%d\n", fn, argp, narg, nret);
siz = narg + nret;
siz = (siz+7) & ~7;
if(siz > 1024)
runtime·throw("runtime.newproc: too many args");
runtime·lock(&runtime·sched);
if((newg = gfget()) != nil){
newg->status = Gwaiting;
if(newg->stackguard - StackGuard - StackSystem != newg->stack0)
runtime·throw("invalid stack in newg");
} else {
newg = runtime·malg(StackMin);
newg->status = Gwaiting;
newg->alllink = runtime·allg;
runtime·allg = newg;
}
sp = newg->stackbase;
sp -= siz;
runtime·mcpy(sp, argp, narg);
if(thechar == '5') {
// caller's LR
sp -= sizeof(void*);
*(void**)sp = nil;
}
newg->sched.sp = sp;
newg->sched.pc = (byte*)runtime·goexit;
newg->sched.g = newg;
newg->entry = fn;
newg->gopc = (uintptr)callerpc;
runtime·sched.gcount++;
runtime·goidgen++;
newg->goid = runtime·goidgen;
newprocreadylocked(newg);
runtime·unlock(&runtime·sched);
return newg;
//printf(" goid=%d\n", newg->goid);
}
#pragma textflag 7
uintptr
runtime·deferproc(int32 siz, byte* fn, ...)
{
Defer *d;
d = runtime·malloc(sizeof(*d) + siz - sizeof(d->args));
d->fn = fn;
d->siz = siz;
d->pc = runtime·getcallerpc(&siz);
if(thechar == '5')
d->argp = (byte*)(&fn+2); // skip caller's saved link register
else
d->argp = (byte*)(&fn+1);
runtime·mcpy(d->args, d->argp, d->siz);
d->link = g->defer;
g->defer = d;
// deferproc returns 0 normally.
// a deferred func that stops a panic
// makes the deferproc return 1.
// the code the compiler generates always
// checks the return value and jumps to the
// end of the function if deferproc returns != 0.
return 0;
}
#pragma textflag 7
void
runtime·deferreturn(uintptr arg0)
{
Defer *d;
byte *argp, *fn;
d = g->defer;
if(d == nil)
return;
argp = (byte*)&arg0;
if(d->argp != argp)
return;
runtime·mcpy(argp, d->args, d->siz);
g->defer = d->link;
fn = d->fn;
runtime·free(d);
runtime·jmpdefer(fn, argp);
}
static void
rundefer(void)
{
Defer *d;
while((d = g->defer) != nil) {
g->defer = d->link;
reflect·call(d->fn, d->args, d->siz);
runtime·free(d);
}
}
// Free stack frames until we hit the last one
// or until we find the one that contains the argp.
static void
unwindstack(G *gp, byte *sp)
{
Stktop *top;
byte *stk;
// Must be called from a different goroutine, usually m->g0.
if(g == gp)
runtime·throw("unwindstack on self");
while((top = (Stktop*)gp->stackbase) != nil && top->stackbase != nil) {
stk = gp->stackguard - StackGuard;
if(stk <= sp && sp < gp->stackbase)
break;
gp->stackbase = top->stackbase;
gp->stackguard = top->stackguard;
if(top->free != 0)
runtime·stackfree(stk, top->free);
}
if(sp != nil && (sp < gp->stackguard - StackGuard || gp->stackbase < sp)) {
runtime·printf("recover: %p not in [%p, %p]\n", sp, gp->stackguard - StackGuard, gp->stackbase);
runtime·throw("bad unwindstack");
}
}
static void
printpanics(Panic *p)
{
if(p->link) {
printpanics(p->link);
runtime·printf("\t");
}
runtime·printf("panic: ");
runtime·printany(p->arg);
if(p->recovered)
runtime·printf(" [recovered]");
runtime·printf("\n");
}
void
runtime·panic(Eface e)
{
Defer *d;
Panic *p;
p = runtime·mal(sizeof *p);
p->arg = e;
p->link = g->panic;
p->stackbase = g->stackbase;
g->panic = p;
for(;;) {
d = g->defer;
if(d == nil)
break;
// take defer off list in case of recursive panic
g->defer = d->link;
g->ispanic = true; // rock for newstack, where reflect.call ends up
reflect·call(d->fn, d->args, d->siz);
if(p->recovered) {
g->panic = p->link;
if(g->panic == nil) // must be done with signal
g->sig = 0;
runtime·free(p);
// put recovering defer back on list
// for scheduler to find.
d->link = g->defer;
g->defer = d;
g->status = Grecovery;
runtime·gosched();
runtime·throw("recovery failed"); // gosched should not return
}
runtime·free(d);
}
// ran out of deferred calls - old-school panic now
runtime·startpanic();
printpanics(g->panic);
runtime·dopanic(0);
}
#pragma textflag 7 /* no split, or else g->stackguard is not the stack for fp */
void
runtime·recover(byte *argp, Eface ret)
{
Stktop *top, *oldtop;
Panic *p;
// Must be a panic going on.
if((p = g->panic) == nil || p->recovered)
goto nomatch;
// Frame must be at the top of the stack segment,
// because each deferred call starts a new stack
// segment as a side effect of using reflect.call.
// (There has to be some way to remember the
// variable argument frame size, and the segment
// code already takes care of that for us, so we
// reuse it.)
//
// As usual closures complicate things: the fp that
// the closure implementation function claims to have
// is where the explicit arguments start, after the
// implicit pointer arguments and PC slot.
// If we're on the first new segment for a closure,
// then fp == top - top->args is correct, but if
// the closure has its own big argument frame and
// allocated a second segment (see below),
// the fp is slightly above top - top->args.
// That condition can't happen normally though
// (stack pointers go down, not up), so we can accept
// any fp between top and top - top->args as
// indicating the top of the segment.
top = (Stktop*)g->stackbase;
if(argp < (byte*)top - top->argsize || (byte*)top < argp)
goto nomatch;
// The deferred call makes a new segment big enough
// for the argument frame but not necessarily big
// enough for the function's local frame (size unknown
// at the time of the call), so the function might have
// made its own segment immediately. If that's the
// case, back top up to the older one, the one that
// reflect.call would have made for the panic.
//
// The fp comparison here checks that the argument
// frame that was copied during the split (the top->args
// bytes above top->fp) abuts the old top of stack.
// This is a correct test for both closure and non-closure code.
oldtop = (Stktop*)top->stackbase;
if(oldtop != nil && top->argp == (byte*)oldtop - top->argsize)
top = oldtop;
// Now we have the segment that was created to
// run this call. It must have been marked as a panic segment.
if(!top->panic)
goto nomatch;
// Okay, this is the top frame of a deferred call
// in response to a panic. It can see the panic argument.
p->recovered = 1;
ret = p->arg;
FLUSH(&ret);
return;
nomatch:
ret.type = nil;
ret.data = nil;
FLUSH(&ret);
}
// Put on gfree list. Sched must be locked.
static void
gfput(G *g)
{
if(g->stackguard - StackGuard - StackSystem != g->stack0)
runtime·throw("invalid stack in gfput");
g->schedlink = runtime·sched.gfree;
runtime·sched.gfree = g;
}
// Get from gfree list. Sched must be locked.
static G*
gfget(void)
{
G *g;
g = runtime·sched.gfree;
if(g)
runtime·sched.gfree = g->schedlink;
return g;
}
void
runtime·Breakpoint(void)
{
runtime·breakpoint();
}
void
runtime·Goexit(void)
{
rundefer();
runtime·goexit();
}
void
runtime·Gosched(void)
{
runtime·gosched();
}
void
runtime·LockOSThread(void)
{
if(runtime·sched.predawn)
runtime·throw("cannot wire during init");
m->lockedg = g;
g->lockedm = m;
}
// delete when scheduler is stronger
int32
runtime·gomaxprocsfunc(int32 n)
{
int32 ret;
runtime·lock(&runtime·sched);
ret = runtime·gomaxprocs;
if (n <= 0)
n = ret;
runtime·gomaxprocs = n;
runtime·sched.mcpumax = n;
// handle fewer procs?
if(runtime·sched.mcpu > runtime·sched.mcpumax) {
runtime·unlock(&runtime·sched);
// just give up the cpu.
// we'll only get rescheduled once the
// number has come down.
runtime·gosched();
return ret;
}
// handle more procs
matchmg();
runtime·unlock(&runtime·sched);
return ret;
}
void
runtime·UnlockOSThread(void)
{
m->lockedg = nil;
g->lockedm = nil;
}
// for testing of wire, unwire
void
runtime·mid(uint32 ret)
{
ret = m->id;
FLUSH(&ret);
}
void
runtime·Goroutines(int32 ret)
{
ret = runtime·sched.gcount;
FLUSH(&ret);
}
int32
runtime·mcount(void)
{
return runtime·sched.mcount;
}