1 files changed, 320 insertions, 0 deletions
diff --git a/src/pkg/runtime/linux/thread.c b/src/pkg/runtime/linux/thread.c
new file mode 100644
index 000000000..4878a00f2
--- /dev/null
+++ b/src/pkg/runtime/linux/thread.c
@@ -0,0 +1,320 @@
+// 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"
+#include "os.h"
+#include "stack.h"
+
+extern SigTab runtime·sigtab[];
+static int32 proccount;
+
+int32 runtime·open(uint8*, int32, int32);
+int32 runtime·close(int32);
+int32 runtime·read(int32, void*, int32);
+
+// 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.
+
+enum
+{
+	MUTEX_UNLOCKED = 0,
+	MUTEX_LOCKED = 1,
+	MUTEX_SLEEPING = 2,
+
+	ACTIVE_SPIN = 4,
+	ACTIVE_SPIN_CNT = 30,
+	PASSIVE_SPIN = 1,
+
+	FUTEX_WAIT = 0,
+	FUTEX_WAKE = 1,
+
+	EINTR = 4,
+	EAGAIN = 11,
+};
+
+// TODO(rsc): I tried using 1<<40 here but futex woke up (-ETIMEDOUT).
+// I wonder if the timespec that gets to the kernel
+// actually has two 32-bit numbers in it, so that
+// a 64-bit 1<<40 ends up being 0 seconds,
+// 1<<8 nanoseconds.
+static Timespec longtime =
+{
+	1<<30,	// 34 years
+	0
+};
+
+// Atomically,
+//	if(*addr == val) sleep
+// Might be woken up spuriously; that's allowed.
+static void
+futexsleep(uint32 *addr, uint32 val)
+{
+	// 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.
+	runtime·futex(addr, FUTEX_WAIT, val, &longtime, nil, 0);
+}
+
+// If any procs are sleeping on addr, wake up at most cnt.
+static void
+futexwakeup(uint32 *addr, uint32 cnt)
+{
+	int64 ret;
+
+	ret = runtime·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;
+}
+
+static int32
+getproccount(void)
+{
+	int32 fd, rd, cnt, cpustrlen;
+	byte *cpustr, *pos, *bufpos;
+	byte buf[256];
+
+	fd = runtime·open((byte*)"/proc/stat", O_RDONLY|O_CLOEXEC, 0);
+	if(fd == -1)
+		return 1;
+	cnt = 0;
+	bufpos = buf;
+	cpustr = (byte*)"\ncpu";
+	cpustrlen = runtime·findnull(cpustr);
+	for(;;) {
+		rd = runtime·read(fd, bufpos, sizeof(buf)-cpustrlen);
+		if(rd == -1)
+			break;
+		bufpos[rd] = 0;
+		for(pos=buf; pos=runtime·strstr(pos, cpustr); cnt++, pos++) {
+		}
+		if(rd < cpustrlen)
+			break;
+		runtime·memmove(buf, bufpos+rd-cpustrlen+1, cpustrlen-1);
+		bufpos = buf+cpustrlen-1;
+	}
+	runtime·close(fd);
+	return cnt ? cnt : 1;
+}
+
+// Possible lock states are MUTEX_UNLOCKED, MUTEX_LOCKED and MUTEX_SLEEPING.
+// MUTEX_SLEEPING means that there is presumably at least one sleeping thread.
+// Note that there can be spinning threads during all states - they do not
+// affect mutex's state.
+static void
+futexlock(Lock *l)
+{
+	uint32 i, v, wait, spin;
+
+	// Speculative grab for lock.
+	v = runtime·xchg(&l->key, MUTEX_LOCKED);
+	if(v == MUTEX_UNLOCKED)
+		return;
+
+	// wait is either MUTEX_LOCKED or MUTEX_SLEEPING
+	// depending on whether there is a thread sleeping
+	// on this mutex.  If we ever change l->key from
+	// MUTEX_SLEEPING to some other value, we must be
+	// careful to change it back to MUTEX_SLEEPING before
+	// returning, to ensure that the sleeping thread gets
+	// its wakeup call.
+	wait = v;
+
+	if(proccount == 0)
+		proccount = getproccount();
+
+	// On uniprocessor's, no point spinning.
+	// On multiprocessors, spin for ACTIVE_SPIN attempts.
+	spin = 0;
+	if(proccount > 1)
+		spin = ACTIVE_SPIN;
+
+	for(;;) {
+		// Try for lock, spinning.
+		for(i = 0; i < spin; i++) {
+			while(l->key == MUTEX_UNLOCKED)
+				if(runtime·cas(&l->key, MUTEX_UNLOCKED, wait))
+						return;
+			runtime·procyield(ACTIVE_SPIN_CNT);
+		}
+
+		// Try for lock, rescheduling.
+		for(i=0; i < PASSIVE_SPIN; i++) {
+			while(l->key == MUTEX_UNLOCKED)
+				if(runtime·cas(&l->key, MUTEX_UNLOCKED, wait))
+					return;
+			runtime·osyield();
+		}
+
+		// Sleep.
+		v = runtime·xchg(&l->key, MUTEX_SLEEPING);
+		if(v == MUTEX_UNLOCKED)
+			return;
+		wait = MUTEX_SLEEPING;
+		futexsleep(&l->key, MUTEX_SLEEPING);
+	}
+}
+
+static void
+futexunlock(Lock *l)
+{
+	uint32 v;
+
+	v = runtime·xchg(&l->key, MUTEX_UNLOCKED);
+	if(v == MUTEX_UNLOCKED)
+		runtime·throw("unlock of unlocked lock");
+	if(v == MUTEX_SLEEPING)
+		futexwakeup(&l->key, 1);
+}
+
+void
+runtime·lock(Lock *l)
+{
+	if(m->locks++ < 0)
+		runtime·throw("runtime·lock: lock count");
+	futexlock(l);
+}
+
+void
+runtime·unlock(Lock *l)
+{
+	if(--m->locks < 0)
+		runtime·throw("runtime·unlock: lock count");
+	futexunlock(l);
+}
+
+
+// One-time notifications.
+void
+runtime·noteclear(Note *n)
+{
+	n->state = 0;
+}
+
+void
+runtime·notewakeup(Note *n)
+{
+	runtime·xchg(&n->state, 1);
+	futexwakeup(&n->state, 1<<30);
+}
+
+void
+runtime·notesleep(Note *n)
+{
+	while(runtime·atomicload(&n->state) == 0)
+		futexsleep(&n->state, 0);
+}
+
+
+// Clone, the Linux rfork.
+enum
+{
+	CLONE_VM = 0x100,
+	CLONE_FS = 0x200,
+	CLONE_FILES = 0x400,
+	CLONE_SIGHAND = 0x800,
+	CLONE_PTRACE = 0x2000,
+	CLONE_VFORK = 0x4000,
+	CLONE_PARENT = 0x8000,
+	CLONE_THREAD = 0x10000,
+	CLONE_NEWNS = 0x20000,
+	CLONE_SYSVSEM = 0x40000,
+	CLONE_SETTLS = 0x80000,
+	CLONE_PARENT_SETTID = 0x100000,
+	CLONE_CHILD_CLEARTID = 0x200000,
+	CLONE_UNTRACED = 0x800000,
+	CLONE_CHILD_SETTID = 0x1000000,
+	CLONE_STOPPED = 0x2000000,
+	CLONE_NEWUTS = 0x4000000,
+	CLONE_NEWIPC = 0x8000000,
+};
+
+void
+runtime·newosproc(M *m, G *g, void *stk, void (*fn)(void))
+{
+	int32 ret;
+	int32 flags;
+
+	/*
+	 * note: strace gets confused if we use CLONE_PTRACE here.
+	 */
+	flags = CLONE_VM	/* share memory */
+		| CLONE_FS	/* share cwd, etc */
+		| CLONE_FILES	/* share fd table */
+		| CLONE_SIGHAND	/* share sig handler table */
+		| CLONE_THREAD	/* revisit - okay for now */
+		;
+
+	m->tls[0] = m->id;	// so 386 asm can find it
+	if(0){
+		runtime·printf("newosproc stk=%p m=%p g=%p fn=%p clone=%p id=%d/%d ostk=%p\n",
+			stk, m, g, fn, runtime·clone, m->id, m->tls[0], &m);
+	}
+
+	if((ret = runtime·clone(flags, stk, m, g, fn)) < 0) {
+		runtime·printf("runtime: failed to create new OS thread (have %d already; errno=%d)\n", runtime·mcount(), -ret);
+		runtime·throw("runtime.newosproc");
+	}
+}
+
+void
+runtime·osinit(void)
+{
+}
+
+void
+runtime·goenvs(void)
+{
+	runtime·goenvs_unix();
+}
+
+// Called to initialize a new m (including the bootstrap m).
+void
+runtime·minit(void)
+{
+	// Initialize signal handling.
+	m->gsignal = runtime·malg(32*1024);	// OS X wants >=8K, Linux >=2K
+	runtime·signalstack(m->gsignal->stackguard - StackGuard, 32*1024);
+}
+
+void
+runtime·sigpanic(void)
+{
+	switch(g->sig) {
+	case SIGBUS:
+		if(g->sigcode0 == BUS_ADRERR && g->sigcode1 < 0x1000)
+			runtime·panicstring("invalid memory address or nil pointer dereference");
+		runtime·printf("unexpected fault address %p\n", g->sigcode1);
+		runtime·throw("fault");
+	case SIGSEGV:
+		if((g->sigcode0 == 0 || g->sigcode0 == SEGV_MAPERR || g->sigcode0 == SEGV_ACCERR) && g->sigcode1 < 0x1000)
+			runtime·panicstring("invalid memory address or nil pointer dereference");
+		runtime·printf("unexpected fault address %p\n", g->sigcode1);
+		runtime·throw("fault");
+	case SIGFPE:
+		switch(g->sigcode0) {
+		case FPE_INTDIV:
+			runtime·panicstring("integer divide by zero");
+		case FPE_INTOVF:
+			runtime·panicstring("integer overflow");
+		}
+		runtime·panicstring("floating point error");
+	}
+	runtime·panicstring(runtime·sigtab[g->sig].name);
+}