runtime, os/signal: use //go:linkname instead of assembly stubs to get access to runtime functions

os/signal depends on a few unexported runtime functions. This removes the
assembly stubs it used to get access to these in favour of using
//go:linkname in runtime to make the functions accessible to os/signal.

This is motivated by ppc64le shared libraries, where you cannot BR to a symbol
defined in a shared library (only BL), but it seems like an improvment anyway.

Change-Id: I09361203ce38070bd3f132f6dc5ac212f2dc6f58
Reviewed-on: https://go-review.googlesource.com/15871
Run-TryBot: Michael Hudson-Doyle <michael.hudson@canonical.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>

1 files changed, 4 insertions, 0 deletions

diff --git a/src/runtime/sigqueue.go b/src/runtime/sigqueue.go
index e6e1a84063..f28067f3f9 100644
--- a/src/runtime/sigqueue.go
+++ b/src/runtime/sigqueue.go
@@ -90,6 +90,7 @@ Send:
 
 // Called to receive the next queued signal.
 // Must only be called from a single goroutine at a time.
+//go:linkname signal_recv os/signal.signal_recv
 func signal_recv() uint32 {
 	for {
 		// Serve any signals from local copy.
@@ -127,6 +128,7 @@ func signal_recv() uint32 {
 }
 
 // Must only be called from a single goroutine at a time.
+//go:linkname signal_enable os/signal.signal_enable
 func signal_enable(s uint32) {
 	if !sig.inuse {
 		// The first call to signal_enable is for us
@@ -145,6 +147,7 @@ func signal_enable(s uint32) {
 }
 
 // Must only be called from a single goroutine at a time.
+//go:linkname signal_disable os/signal.signal_disable
 func signal_disable(s uint32) {
 	if s >= uint32(len(sig.wanted)*32) {
 		return
@@ -154,6 +157,7 @@ func signal_disable(s uint32) {
 }
 
 // Must only be called from a single goroutine at a time.
+//go:linkname signal_ignore os/signal.signal_ignore
 func signal_ignore(s uint32) {
 	if s >= uint32(len(sig.wanted)*32) {
 		return