1 files changed, 342 insertions, 0 deletions
diff --git a/src/runtime/os_linux.c b/src/runtime/os_linux.c
new file mode 100644
index 000000000..0d8ffc995
--- /dev/null
+++ b/src/runtime/os_linux.c
@@ -0,0 +1,342 @@
+// 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_GOOS_GOARCH.h"
+#include "os_GOOS.h"
+#include "signal_unix.h"
+#include "stack.h"
+#include "textflag.h"
+
+extern SigTab runtime·sigtab[];
+
+static Sigset sigset_none;
+static Sigset sigset_all = { ~(uint32)0, ~(uint32)0 };
+
+// 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
+{
+	FUTEX_WAIT = 0,
+	FUTEX_WAKE = 1,
+};
+
+// Atomically,
+//	if(*addr == val) sleep
+// Might be woken up spuriously; that's allowed.
+// Don't sleep longer than ns; ns < 0 means forever.
+#pragma textflag NOSPLIT
+void
+runtime·futexsleep(uint32 *addr, uint32 val, int64 ns)
+{
+	Timespec 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.
+
+	if(ns < 0) {
+		runtime·futex(addr, FUTEX_WAIT, val, nil, nil, 0);
+		return;
+	}
+	// NOTE: tv_nsec is int64 on amd64, so this assumes a little-endian system.
+	ts.tv_nsec = 0;
+	ts.tv_sec = runtime·timediv(ns, 1000000000LL, (int32*)&ts.tv_nsec);
+	runtime·futex(addr, FUTEX_WAIT, val, &ts, nil, 0);
+}
+
+static void badfutexwakeup(void);
+
+// If any procs are sleeping on addr, wake up at most cnt.
+#pragma textflag NOSPLIT
+void
+runtime·futexwakeup(uint32 *addr, uint32 cnt)
+{
+	int64 ret;
+	void (*fn)(void);
+
+	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.
+	g->m->ptrarg[0] = addr;
+	g->m->scalararg[0] = (int32)ret; // truncated but fine
+	fn = badfutexwakeup;
+	if(g == g->m->gsignal)
+		fn();
+	else
+		runtime·onM(&fn);
+	*(int32*)0x1006 = 0x1006;
+}
+
+static void
+badfutexwakeup(void)
+{
+	void *addr;
+	int64 ret;
+	
+	addr = g->m->ptrarg[0];
+	ret = (int32)g->m->scalararg[0];
+	runtime·printf("futexwakeup addr=%p returned %D\n", addr, ret);
+}
+
+extern runtime·sched_getaffinity(uintptr pid, uintptr len, uintptr *buf);
+static int32
+getproccount(void)
+{
+	uintptr buf[16], t;
+	int32 r, cnt, i;
+
+	cnt = 0;
+	r = runtime·sched_getaffinity(0, sizeof(buf), buf);
+	if(r > 0)
+	for(i = 0; i < r/sizeof(buf[0]); i++) {
+		t = buf[i];
+		t = t - ((t >> 1) & 0x5555555555555555ULL);
+		t = (t & 0x3333333333333333ULL) + ((t >> 2) & 0x3333333333333333ULL);
+		cnt += (int32)((((t + (t >> 4)) & 0xF0F0F0F0F0F0F0FULL) * 0x101010101010101ULL) >> 56);
+	}
+
+	return cnt ? cnt : 1;
+}
+
+// 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 *mp, void *stk)
+{
+	int32 ret;
+	int32 flags;
+	Sigset oset;
+
+	/*
+	 * 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 */
+		;
+
+	mp->tls[0] = mp->id;	// so 386 asm can find it
+	if(0){
+		runtime·printf("newosproc stk=%p m=%p g=%p clone=%p id=%d/%d ostk=%p\n",
+			stk, mp, mp->g0, runtime·clone, mp->id, (int32)mp->tls[0], &mp);
+	}
+
+	// Disable signals during clone, so that the new thread starts
+	// with signals disabled.  It will enable them in minit.
+	runtime·rtsigprocmask(SIG_SETMASK, &sigset_all, &oset, sizeof oset);
+	ret = runtime·clone(flags, stk, mp, mp->g0, runtime·mstart);
+	runtime·rtsigprocmask(SIG_SETMASK, &oset, nil, sizeof oset);
+
+	if(ret < 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)
+{
+	runtime·ncpu = getproccount();
+}
+
+// Random bytes initialized at startup.  These come
+// from the ELF AT_RANDOM auxiliary vector (vdso_linux_amd64.c).
+byte*	runtime·startup_random_data;
+uint32	runtime·startup_random_data_len;
+
+#pragma textflag NOSPLIT
+void
+runtime·get_random_data(byte **rnd, int32 *rnd_len)
+{
+	if(runtime·startup_random_data != nil) {
+		*rnd = runtime·startup_random_data;
+		*rnd_len = runtime·startup_random_data_len;
+	} else {
+		#pragma dataflag NOPTR
+		static byte urandom_data[HashRandomBytes];
+		int32 fd;
+		fd = runtime·open("/dev/urandom", 0 /* O_RDONLY */, 0);
+		if(runtime·read(fd, urandom_data, HashRandomBytes) == HashRandomBytes) {
+			*rnd = urandom_data;
+			*rnd_len = HashRandomBytes;
+		} else {
+			*rnd = nil;
+			*rnd_len = 0;
+		}
+		runtime·close(fd);
+	}
+}
+
+void
+runtime·goenvs(void)
+{
+	runtime·goenvs_unix();
+}
+
+// Called to initialize a new m (including the bootstrap m).
+// Called on the parent thread (main thread in case of bootstrap), can allocate memory.
+void
+runtime·mpreinit(M *mp)
+{
+	mp->gsignal = runtime·malg(32*1024);	// OS X wants >=8K, Linux >=2K
+	mp->gsignal->m = mp;
+}
+
+// Called to initialize a new m (including the bootstrap m).
+// Called on the new thread, can not allocate memory.
+void
+runtime·minit(void)
+{
+	// Initialize signal handling.
+	runtime·signalstack((byte*)g->m->gsignal->stack.lo, 32*1024);
+	runtime·rtsigprocmask(SIG_SETMASK, &sigset_none, nil, sizeof(Sigset));
+}
+
+// Called from dropm to undo the effect of an minit.
+void
+runtime·unminit(void)
+{
+	runtime·signalstack(nil, 0);
+}
+
+uintptr
+runtime·memlimit(void)
+{
+	Rlimit rl;
+	extern byte runtime·text[], runtime·end[];
+	uintptr used;
+
+	if(runtime·getrlimit(RLIMIT_AS, &rl) != 0)
+		return 0;
+	if(rl.rlim_cur >= 0x7fffffff)
+		return 0;
+
+	// Estimate our VM footprint excluding the heap.
+	// Not an exact science: use size of binary plus
+	// some room for thread stacks.
+	used = runtime·end - runtime·text + (64<<20);
+	if(used >= rl.rlim_cur)
+		return 0;
+
+	// If there's not at least 16 MB left, we're probably
+	// not going to be able to do much.  Treat as no limit.
+	rl.rlim_cur -= used;
+	if(rl.rlim_cur < (16<<20))
+		return 0;
+
+	return rl.rlim_cur - used;
+}
+
+#ifdef GOARCH_386
+#define sa_handler k_sa_handler
+#endif
+
+/*
+ * This assembler routine takes the args from registers, puts them on the stack,
+ * and calls sighandler().
+ */
+extern void runtime·sigtramp(void);
+extern void runtime·sigreturn(void);	// calls rt_sigreturn, only used with SA_RESTORER
+
+void
+runtime·setsig(int32 i, GoSighandler *fn, bool restart)
+{
+	SigactionT sa;
+
+	runtime·memclr((byte*)&sa, sizeof sa);
+	sa.sa_flags = SA_ONSTACK | SA_SIGINFO | SA_RESTORER;
+	if(restart)
+		sa.sa_flags |= SA_RESTART;
+	sa.sa_mask = ~0ULL;
+	// Although Linux manpage says "sa_restorer element is obsolete and
+	// should not be used". x86_64 kernel requires it. Only use it on
+	// x86.
+#ifdef GOARCH_386
+	sa.sa_restorer = (void*)runtime·sigreturn;
+#endif
+#ifdef GOARCH_amd64
+	sa.sa_restorer = (void*)runtime·sigreturn;
+#endif
+	if(fn == runtime·sighandler)
+		fn = (void*)runtime·sigtramp;
+	sa.sa_handler = fn;
+	if(runtime·rt_sigaction(i, &sa, nil, sizeof(sa.sa_mask)) != 0)
+		runtime·throw("rt_sigaction failure");
+}
+
+GoSighandler*
+runtime·getsig(int32 i)
+{
+	SigactionT sa;
+
+	runtime·memclr((byte*)&sa, sizeof sa);
+	if(runtime·rt_sigaction(i, nil, &sa, sizeof(sa.sa_mask)) != 0)
+		runtime·throw("rt_sigaction read failure");
+	if((void*)sa.sa_handler == runtime·sigtramp)
+		return runtime·sighandler;
+	return (void*)sa.sa_handler;
+}
+
+void
+runtime·signalstack(byte *p, int32 n)
+{
+	SigaltstackT st;
+
+	st.ss_sp = p;
+	st.ss_size = n;
+	st.ss_flags = 0;
+	if(p == nil)
+		st.ss_flags = SS_DISABLE;
+	runtime·sigaltstack(&st, nil);
+}
+
+void
+runtime·unblocksignals(void)
+{
+	runtime·rtsigprocmask(SIG_SETMASK, &sigset_none, nil, sizeof sigset_none);
+}
+
+#pragma textflag NOSPLIT
+int8*
+runtime·signame(int32 sig)
+{
+	return runtime·sigtab[sig].name;
+}