runtime: convert openbsd/amd64 locking to libc

Switch openbsd/amd64 to locking via libc, rather than performing direct
system calls.

Update #36435

Change-Id: I5e92bd70ce557b78ff385577088a9775cc468ea9
Reviewed-on: https://go-review.googlesource.com/c/go/+/270378
Trust: Joel Sing <joel@sing.id.au>
Run-TryBot: Joel Sing <joel@sing.id.au>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

src/runtime/os_openbsd.go

@@ -46,14 +46,6 @@ func raiseproc(sig uint32)
 func getthrid() int32
 func thrkill(tid int32, sig int)
 
-//go:noescape
-func thrsleep(ident uintptr, clock_id int32, tsp *timespec, lock uintptr, abort *uint32) int32
-
-//go:noescape
-func thrwakeup(ident uintptr, n int32) int32
-
-func osyield()
-
 func kqueue() int32
 
 //go:noescape

src/runtime/os_openbsd_syscall1.go

@@ -0,0 +1,15 @@
+// Copyright 2011 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 openbsd,!amd64
+
+package runtime
+
+//go:noescape
+func thrsleep(ident uintptr, clock_id int32, tsp *timespec, lock uintptr, abort *uint32) int32
+
+//go:noescape
+func thrwakeup(ident uintptr, n int32) int32
+
+func osyield()

src/runtime/sys_openbsd1.go

@@ -0,0 +1,34 @@
+// Copyright 2020 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 openbsd,amd64
+
+package runtime
+
+import "unsafe"
+
+//go:nosplit
+//go:cgo_unsafe_args
+func thrsleep(ident uintptr, clock_id int32, tsp *timespec, lock uintptr, abort *uint32) int32 {
+	return libcCall(unsafe.Pointer(funcPC(thrsleep_trampoline)), unsafe.Pointer(&ident))
+}
+func thrsleep_trampoline()
+
+//go:nosplit
+//go:cgo_unsafe_args
+func thrwakeup(ident uintptr, n int32) int32 {
+	return libcCall(unsafe.Pointer(funcPC(thrwakeup_trampoline)), unsafe.Pointer(&ident))
+}
+func thrwakeup_trampoline()
+
+func osyield() {
+	libcCall(unsafe.Pointer(funcPC(sched_yield_trampoline)), unsafe.Pointer(nil))
+}
+func sched_yield_trampoline()
+
+//go:cgo_import_dynamic libc_thrsleep __thrsleep "libc.so"
+//go:cgo_import_dynamic libc_thrwakeup __thrwakeup "libc.so"
+//go:cgo_import_dynamic libc_sched_yield sched_yield "libc.so"
+
+//go:cgo_import_dynamic _ _ "libc.so"

src/runtime/sys_openbsd_amd64.s

@@ -168,28 +168,32 @@ TEXT runtime·pthread_kill_trampoline(SB),NOSPLIT,$0
 	POPQ	BP
 	RET
 
-TEXT runtime·osyield(SB),NOSPLIT,$0
+TEXT runtime·thrsleep_trampoline(SB),NOSPLIT,$0
-	MOVL	$298, AX		// sys_sched_yield
+	PUSHQ	BP
-	SYSCALL
+	MOVQ	SP, BP
+	MOVL	8(DI), SI		// arg 2 - clock_id
+	MOVQ	16(DI), DX		// arg 3 - abstime
+	MOVQ	24(DI), CX		// arg 3 - lock
+	MOVQ	32(DI), R8		// arg 4 - abort
+	MOVQ	0(DI), DI		// arg 1 - id
+	CALL	libc_thrsleep(SB)
+	POPQ	BP
 	RET
 
-TEXT runtime·thrsleep(SB),NOSPLIT,$0
+TEXT runtime·thrwakeup_trampoline(SB),NOSPLIT,$0
-	MOVQ	ident+0(FP), DI		// arg 1 - ident
+	PUSHQ	BP
-	MOVL	clock_id+8(FP), SI		// arg 2 - clock_id
+	MOVQ	SP, BP
-	MOVQ	tsp+16(FP), DX		// arg 3 - tp
+	MOVL	8(DI), SI		// arg 2 - count
-	MOVQ	lock+24(FP), R10		// arg 4 - lock
+	MOVQ	0(DI), DI		// arg 1 - id
-	MOVQ	abort+32(FP), R8		// arg 5 - abort
+	CALL	libc_thrwakeup(SB)
-	MOVL	$94, AX			// sys___thrsleep
+	POPQ	BP
-	SYSCALL
-	MOVL	AX, ret+40(FP)
 	RET
 
-TEXT runtime·thrwakeup(SB),NOSPLIT,$0
+TEXT runtime·sched_yield_trampoline(SB),NOSPLIT,$0
-	MOVQ	ident+0(FP), DI		// arg 1 - ident
+	PUSHQ	BP
-	MOVL	n+8(FP), SI		// arg 2 - n
+	MOVQ	SP, BP
-	MOVL	$301, AX		// sys___thrwakeup
+	CALL	libc_sched_yield(SB)
-	SYSCALL
+	POPQ	BP
-	MOVL	AX, ret+16(FP)
 	RET
 
 // Exit the entire program (like C exit)