runtime: restructured os1_linux.go, added mips64 support

Linux/mips64 uses a different type of sigset. To deal with it, related
functions in os1_linux.go is refactored to os1_linux_generic.go
(used for non-mips64 architectures), and os1_linux_mips64x.go (only used
in mips64{,le}), to avoid code copying.

Change-Id: I5cadfccd86bfc4b30bf97e12607c3c614903ea4c
Reviewed-on: https://go-review.googlesource.com/14991
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/runtime/os1_linux.go

@@ -6,8 +6,6 @@ package runtime
 
 import "unsafe"
 
-var sigset_all sigset = sigset{^uint32(0), ^uint32(0)}
-
 // Linux futex.
 //
 //	futexsleep(uint32 *addr, uint32 val)
@@ -221,7 +219,7 @@ func minit() {
 	nmask := *(*sigset)(unsafe.Pointer(&_g_.m.sigmask))
 	for i := range sigtable {
 		if sigtable[i].flags&_SigUnblock != 0 {
-			nmask[(i-1)/32] &^= 1 << ((uint32(i) - 1) & 31)
+			sigdelset(&nmask, i)
 		}
 	}
 	rtsigprocmask(_SIG_SETMASK, &nmask, nil, int32(unsafe.Sizeof(nmask)))
@@ -281,7 +279,7 @@ func setsig(i int32, fn uintptr, restart bool) {
 	if restart {
 		sa.sa_flags |= _SA_RESTART
 	}
-	sa.sa_mask = ^uint64(0)
+	sigfillset(&sa.sa_mask)
 	// Although Linux manpage says "sa_restorer element is obsolete and
 	// should not be used". x86_64 kernel requires it. Only use it on
 	// x86.
@@ -338,12 +336,12 @@ func signalstack(s *stack) {
 
 func updatesigmask(m sigmask) {
 	var mask sigset
-	copy(mask[:], m[:])
+	sigcopyset(&mask, m)
 	rtsigprocmask(_SIG_SETMASK, &mask, nil, int32(unsafe.Sizeof(mask)))
 }
 
 func unblocksig(sig int32) {
 	var mask sigset
-	mask[(sig-1)/32] |= 1 << ((uint32(sig) - 1) & 31)
+	sigaddset(&mask, int(sig))
 	rtsigprocmask(_SIG_UNBLOCK, &mask, nil, int32(unsafe.Sizeof(mask)))
 }

src/runtime/os1_linux_generic.go

@@ -0,0 +1,27 @@
+// 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.
+
+// +build !mips64
+// +build !mips64le
+// +build linux
+
+package runtime
+
+var sigset_all = sigset{^uint32(0), ^uint32(0)}
+
+func sigaddset(mask *sigset, i int) {
+	(*mask)[(i-1)/32] |= 1 << ((uint32(i) - 1) & 31)
+}
+
+func sigdelset(mask *sigset, i int) {
+	(*mask)[(i-1)/32] &^= 1 << ((uint32(i) - 1) & 31)
+}
+
+func sigfillset(mask *uint64) {
+	*mask = ^uint64(0)
+}
+
+func sigcopyset(mask *sigset, m sigmask) {
+	copy((*mask)[:], m[:])
+}

src/runtime/os1_linux_mips64x.go

@@ -0,0 +1,26 @@
+// Copyright 2015 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.
+
+// +build mips64 mips64le
+// +build linux
+
+package runtime
+
+var sigset_all = sigset{^uint64(0), ^uint64(0)}
+
+func sigaddset(mask *sigset, i int) {
+	(*mask)[(i-1)/64] |= 1 << ((uint32(i) - 1) & 63)
+}
+
+func sigdelset(mask *sigset, i int) {
+	(*mask)[(i-1)/64] &^= 1 << ((uint32(i) - 1) & 63)
+}
+
+func sigfillset(mask *[2]uint64) {
+	(*mask)[0], (*mask)[1] = ^uint64(0), ^uint64(0)
+}
+
+func sigcopyset(mask *sigset, m sigmask) {
+	(*mask)[0] = uint64(m[0]) | uint64(m[1])<<32
+}