84 lines
1.9 KiB
C
84 lines
1.9 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 "defs.h"
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#include "signal_unix.h"
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// Linux futex.
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//
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// futexsleep(uint32 *addr, uint32 val)
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// futexwakeup(uint32 *addr)
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//
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// Futexsleep atomically checks if *addr == val and if so, sleeps on addr.
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// Futexwakeup wakes up threads sleeping on addr.
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// Futexsleep is allowed to wake up spuriously.
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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;
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int32 nsec;
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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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if(ns < 0) {
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syscall(__NR_futex, addr, FUTEX_WAIT, val, nil, nil, 0);
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return;
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}
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ts.tv_sec = runtime_timediv(ns, 1000000000LL, &nsec);
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ts.tv_nsec = nsec;
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syscall(__NR_futex, addr, FUTEX_WAIT, val, &ts, 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 %D\n", addr, ret);
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*(int32*)0x1006 = 0x1006;
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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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void
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runtime_goenvs(void)
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{
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runtime_goenvs_unix();
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}
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