122 lines
2.6 KiB
C
122 lines
2.6 KiB
C
// 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 "defs.h"
|
|
|
|
// Linux futex.
|
|
//
|
|
// futexsleep(uint32 *addr, uint32 val)
|
|
// futexwakeup(uint32 *addr)
|
|
//
|
|
// Futexsleep atomically checks if *addr == val and if so, sleeps on addr.
|
|
// Futexwakeup wakes up threads sleeping on addr.
|
|
// Futexsleep is allowed to wake up spuriously.
|
|
|
|
#include <errno.h>
|
|
#include <string.h>
|
|
#include <time.h>
|
|
#include <sys/types.h>
|
|
#include <sys/stat.h>
|
|
#include <fcntl.h>
|
|
#include <unistd.h>
|
|
#include <syscall.h>
|
|
#include <linux/futex.h>
|
|
|
|
typedef struct timespec Timespec;
|
|
|
|
// Atomically,
|
|
// if(*addr == val) sleep
|
|
// Might be woken up spuriously; that's allowed.
|
|
// Don't sleep longer than ns; ns < 0 means forever.
|
|
void
|
|
runtime_futexsleep(uint32 *addr, uint32 val, int64 ns)
|
|
{
|
|
Timespec ts, *tsp;
|
|
|
|
if(ns < 0)
|
|
tsp = nil;
|
|
else {
|
|
ts.tv_sec = ns/1000000000LL;
|
|
ts.tv_nsec = ns%1000000000LL;
|
|
// Avoid overflow
|
|
if(ts.tv_sec > 1<<30)
|
|
ts.tv_sec = 1<<30;
|
|
tsp = &ts;
|
|
}
|
|
|
|
// Some Linux kernels have a bug where futex of
|
|
// FUTEX_WAIT returns an internal error code
|
|
// as an errno. Libpthread ignores the return value
|
|
// here, and so can we: as it says a few lines up,
|
|
// spurious wakeups are allowed.
|
|
syscall(__NR_futex, addr, FUTEX_WAIT, val, tsp, nil, 0);
|
|
}
|
|
|
|
// If any procs are sleeping on addr, wake up at most cnt.
|
|
void
|
|
runtime_futexwakeup(uint32 *addr, uint32 cnt)
|
|
{
|
|
int64 ret;
|
|
|
|
ret = syscall(__NR_futex, addr, FUTEX_WAKE, cnt, nil, nil, 0);
|
|
|
|
if(ret >= 0)
|
|
return;
|
|
|
|
// I don't know that futex wakeup can return
|
|
// EAGAIN or EINTR, but if it does, it would be
|
|
// safe to loop and call futex again.
|
|
runtime_printf("futexwakeup addr=%p returned %D\n", addr, ret);
|
|
*(int32*)0x1006 = 0x1006;
|
|
}
|
|
|
|
#ifndef O_CLOEXEC
|
|
#define O_CLOEXEC 0
|
|
#endif
|
|
|
|
static int32
|
|
getproccount(void)
|
|
{
|
|
int32 fd, rd, cnt, cpustrlen;
|
|
const char *cpustr;
|
|
const byte *pos;
|
|
byte *bufpos;
|
|
byte buf[256];
|
|
|
|
fd = open("/proc/stat", O_RDONLY|O_CLOEXEC, 0);
|
|
if(fd == -1)
|
|
return 1;
|
|
cnt = 0;
|
|
bufpos = buf;
|
|
cpustr = "\ncpu";
|
|
cpustrlen = strlen(cpustr);
|
|
for(;;) {
|
|
rd = read(fd, bufpos, sizeof(buf)-cpustrlen);
|
|
if(rd == -1)
|
|
break;
|
|
bufpos[rd] = 0;
|
|
for(pos=buf; (pos=(const byte*)strstr((const char*)pos, cpustr)) != nil; cnt++, pos++) {
|
|
}
|
|
if(rd < cpustrlen)
|
|
break;
|
|
memmove(buf, bufpos+rd-cpustrlen+1, cpustrlen-1);
|
|
bufpos = buf+cpustrlen-1;
|
|
}
|
|
close(fd);
|
|
return cnt ? cnt : 1;
|
|
}
|
|
|
|
void
|
|
runtime_osinit(void)
|
|
{
|
|
runtime_ncpu = getproccount();
|
|
}
|
|
|
|
void
|
|
runtime_goenvs(void)
|
|
{
|
|
runtime_goenvs_unix();
|
|
}
|