syscall: add syscall support for openbsd/riscv64 port

Updates #55999

Change-Id: I5b8452207e951e543b9be42ebcb7d62c0c023f08
Reviewed-on: https://go-review.googlesource.com/c/go/+/518627
Reviewed-by: Ian Lance Taylor <[email protected]>
Run-TryBot: Joel Sing <[email protected]>
Reviewed-by: Michael Pratt <[email protected]>
Reviewed-by: Aaron Bieber <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>

src/syscall/asm_openbsd_riscv64.s

@@ -0,0 +1,32 @@
+// Copyright 2023 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 "textflag.h"
+
+//
+// System call support for RISCV64, OpenBSD
+//
+
+// Provide these function names via assembly so they are provided as ABI0,
+// rather than ABIInternal.
+
+// func Syscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno)
+TEXT	·Syscall(SB),NOSPLIT,$0-56
+	JMP	·syscallInternal(SB)
+
+// func Syscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno)
+TEXT	·Syscall6(SB),NOSPLIT,$0-80
+	JMP	·syscall6Internal(SB)
+
+// func RawSyscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno)
+TEXT	·RawSyscall(SB),NOSPLIT,$0-56
+	JMP	·rawSyscallInternal(SB)
+
+// func RawSyscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno)
+TEXT	·RawSyscall6(SB),NOSPLIT,$0-80
+	JMP	·rawSyscall6Internal(SB)
+
+// func Syscall9(trap, a1, a2, a3, a4, a5, a6, a7, a8, a9 uintptr) (r1, r2 uintptr, err Errno)
+TEXT	·Syscall9(SB),NOSPLIT,$0-104
+	JMP	·syscall9Internal(SB)

src/syscall/mkall.sh

@@ -367,6 +367,17 @@ openbsd_ppc64)
 	# API consistent between platforms.
 	mktypes="GOARCH=$GOARCH go tool cgo -godefs -- -fsigned-char"
 	mkasm="go run mkasm.go"
+openbsd_riscv64)
+	GOOSARCH_in="syscall_openbsd_libc.go syscall_openbsd_$GOARCH.go"
+	mkerrors="$mkerrors -m64"
+	mksyscall="./mksyscall.pl -openbsd -libc"
+	mksysctl="./mksysctl_openbsd.pl"
+	zsysctl="zsysctl_openbsd.go"
+	mksysnum="curl -s 'http://cvsweb.openbsd.org/cgi-bin/cvsweb/~checkout~/src/sys/kern/syscalls.master' | ./mksysnum_openbsd.pl"
+	# Let the type of C char be signed to make the bare syscall
+	# API consistent between platforms.
+	mktypes="GOARCH=$GOARCH go tool cgo -godefs -- -fsigned-char"
+	mkasm="go run mkasm.go"
 	;;
 plan9_386)
 	mkerrors=

src/syscall/syscall_openbsd_riscv64.go

@@ -0,0 +1,38 @@
+// Copyright 2023 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.
+
+package syscall
+
+func setTimespec(sec, nsec int64) Timespec {
+	return Timespec{Sec: sec, Nsec: nsec}
+}
+
+func setTimeval(sec, usec int64) Timeval {
+	return Timeval{Sec: sec, Usec: usec}
+}
+
+func SetKevent(k *Kevent_t, fd, mode, flags int) {
+	k.Ident = uint64(fd)
+	k.Filter = int16(mode)
+	k.Flags = uint16(flags)
+}
+
+func (iov *Iovec) SetLen(length int) {
+	iov.Len = uint64(length)
+}
+
+func (msghdr *Msghdr) SetControllen(length int) {
+	msghdr.Controllen = uint32(length)
+}
+
+func (cmsg *Cmsghdr) SetLen(length int) {
+	cmsg.Len = uint32(length)
+}
+
+// RTM_LOCK only exists in OpenBSD 6.3 and earlier.
+const RTM_LOCK = 0x8
+
+// SYS___SYSCTL only exists in OpenBSD 5.8 and earlier, when it was
+// was renamed to SYS_SYSCTL.
+const SYS___SYSCTL = SYS_SYSCTL