106 lines
2.3 KiB
C
106 lines
2.3 KiB
C
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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#include "runtime.h"
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#include <errno.h>
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#include <string.h>
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#include <time.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <syscall.h>
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#include <linux/futex.h>
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typedef struct timespec Timespec;
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// Atomically,
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// if(*addr == val) sleep
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// Might be woken up spuriously; that's allowed.
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// Don't sleep longer than ns; ns < 0 means forever.
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void
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runtime_futexsleep(uint32 *addr, uint32 val, int64 ns)
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{
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Timespec ts, *tsp;
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if(ns < 0)
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tsp = nil;
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else {
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ts.tv_sec = ns/1000000000LL;
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ts.tv_nsec = ns%1000000000LL;
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// Avoid overflow
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if(ts.tv_sec > 1<<30)
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ts.tv_sec = 1<<30;
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tsp = &ts;
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}
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// Some Linux kernels have a bug where futex of
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// FUTEX_WAIT returns an internal error code
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// as an errno. Libpthread ignores the return value
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// here, and so can we: as it says a few lines up,
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// spurious wakeups are allowed.
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syscall(__NR_futex, addr, FUTEX_WAIT, val, tsp, nil, 0);
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}
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// If any procs are sleeping on addr, wake up at most cnt.
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void
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runtime_futexwakeup(uint32 *addr, uint32 cnt)
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{
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int64 ret;
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ret = syscall(__NR_futex, addr, FUTEX_WAKE, cnt, nil, nil, 0);
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if(ret >= 0)
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return;
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// I don't know that futex wakeup can return
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// EAGAIN or EINTR, but if it does, it would be
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// safe to loop and call futex again.
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runtime_printf("futexwakeup addr=%p returned %lld\n", addr, (long long)ret);
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*(int32*)0x1006 = 0x1006;
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}
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#ifndef O_CLOEXEC
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#define O_CLOEXEC 0
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#endif
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static int32
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getproccount(void)
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{
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int32 fd, rd, cnt, cpustrlen;
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const char *cpustr;
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const byte *pos;
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byte *bufpos;
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byte buf[256];
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fd = open("/proc/stat", O_RDONLY|O_CLOEXEC, 0);
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if(fd == -1)
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return 1;
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cnt = 0;
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bufpos = buf;
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cpustr = "\ncpu";
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cpustrlen = strlen(cpustr);
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for(;;) {
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rd = read(fd, bufpos, sizeof(buf)-cpustrlen);
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if(rd == -1)
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break;
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bufpos[rd] = 0;
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for(pos=buf; (pos=(const byte*)strstr((const char*)pos, cpustr)) != nil; cnt++, pos++) {
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}
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if(rd < cpustrlen)
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break;
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memmove(buf, bufpos+rd-cpustrlen+1, cpustrlen-1);
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bufpos = buf+cpustrlen-1;
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}
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close(fd);
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return cnt ? cnt : 1;
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}
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void
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runtime_osinit(void)
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{
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runtime_ncpu = getproccount();
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}
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