runtime: implement part of library initialization in Go

All architectures supporting c-shared and c-archive share the same
initialization code in assembly, and most of it can be implemented in
pure Go.

Cq-Include-Trybots: luci.golang.try:gotip-darwin-arm64-longtest,gotip-linux-ppc64le_power10,gotip-linux-riscv64,gotip-linux-loong64,gotip-linux-s390x
Change-Id: Iaa9fb7d6f9ca8785f1098461646d607ef6b00d47
Reviewed-on: https://go-review.googlesource.com/c/go/+/706417
Auto-Submit: Quim Muntal <quimmuntal@gmail.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>

1 files changed, 21 insertions, 0 deletions

diff --git a/src/runtime/proc.go b/src/runtime/proc.go
index db4febace9..71e80e9cb7 100644
--- a/src/runtime/proc.go
+++ b/src/runtime/proc.go
@@ -8156,3 +8156,24 @@ func doInit1(t *initTask) {
 		t.state = 2 // initialization done
 	}
 }
+
+// libInit is common startup code for most architectures when
+// using -buildmode=c-archive or -buildmode=c-shared.
+//
+// May run with m.p==nil, so write barriers are not allowed.
+//
+//go:nowritebarrierrec
+//go:nosplit
+func libInit() {
+	// Synchronous initialization.
+	libpreinit()
+
+	// Asynchronous initialization.
+	// Prefer creating a thread via cgo if it is available.
+	if _cgo_sys_thread_create != nil {
+		asmcgocall(_cgo_sys_thread_create, unsafe.Pointer(abi.FuncPCABIInternal(rt0_lib_go)))
+	} else {
+		const stackSize = 0x800000 // 8192KB
+		newosproc0(stackSize, unsafe.Pointer(abi.FuncPCABIInternal(rt0_lib_go)))
+	}
+}