internal/runtime/syscall: rename to internal/runtime/syscall/linux

All code in internal/runtime/syscall is Linux-specific, so better
move it to a new linux sub-directory. This way it will be easier
to factor out runtime syscall code from other platforms, e.g.
Windows.

Updates #51087.

Change-Id: Idd2a52444b33bf3ad576b47fd232e990cdc8ae75
Reviewed-on: https://go-review.googlesource.com/c/go/+/689155
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

src/cmd/internal/objabi/pkgspecial.go

@@ -56,7 +56,7 @@ var runtimePkgs = []string{
 	"internal/runtime/math",
 	"internal/runtime/strconv",
 	"internal/runtime/sys",
-	"internal/runtime/syscall",
+	"internal/runtime/syscall/linux",
 
 	"internal/abi",
 	"internal/bytealg",
@@ -94,7 +94,7 @@ var allowAsmABIPkgs = []string{
 	"syscall",
 	"internal/bytealg",
 	"internal/chacha8rand",
-	"internal/runtime/syscall",
+	"internal/runtime/syscall/linux",
 	"internal/runtime/startlinetest",
 }
 

src/go/build/deps_test.go

@@ -91,7 +91,7 @@ var depsRules = `
 	< internal/msan
 	< internal/asan
 	< internal/runtime/sys
-	< internal/runtime/syscall
+	< internal/runtime/syscall/linux
 	< internal/runtime/atomic
 	< internal/runtime/exithook
 	< internal/runtime/gc

src/internal/coverage/pkid.go

@@ -31,7 +31,7 @@ package coverage
 //    slot: 6 path='internal/runtime/math'  hard-coded id: 6
 //    slot: 7 path='internal/bytealg'  hard-coded id: 7
 //    slot: 8 path='internal/goexperiment'
-//    slot: 9 path='internal/runtime/syscall'  hard-coded id: 8
+//    slot: 9 path='internal/runtime/syscall/linux'  hard-coded id: 8
 //    slot: 10 path='runtime'  hard-coded id: 9
 //    fatal error: runtime.addCovMeta
 //
@@ -66,7 +66,7 @@ var rtPkgs = [...]string{
 	"internal/runtime/strconv",
 	"internal/runtime/sys",
 	"internal/runtime/maps",
-	"internal/runtime/syscall",
+	"internal/runtime/syscall/linux",
 	"internal/runtime/cgroup",
 	"internal/stringslite",
 	"runtime",

src/internal/runtime/cgroup/cgroup_linux.go

@@ -7,7 +7,7 @@ package cgroup
 import (
 	"internal/bytealg"
 	"internal/runtime/strconv"
-	"internal/runtime/syscall"
+	"internal/runtime/syscall/linux"
 )
 
 var (
@@ -77,10 +77,10 @@ type CPU struct {
 func (c CPU) Close() {
 	switch c.version {
 	case V1:
-		syscall.Close(c.quotaFD)
+		linux.Close(c.quotaFD)
-		syscall.Close(c.periodFD)
+		linux.Close(c.periodFD)
 	case V2:
-		syscall.Close(c.quotaFD)
+		linux.Close(c.quotaFD)
 	default:
 		throw("impossible cgroup version")
 	}
@@ -112,7 +112,7 @@ func OpenCPU(scratch []byte) (CPU, error) {
 	case 1:
 		n2 := copy(base[n:], v1QuotaFile)
 		path := base[:n+n2]
-		quotaFD, errno := syscall.Open(&path[0], syscall.O_RDONLY|syscall.O_CLOEXEC, 0)
+		quotaFD, errno := linux.Open(&path[0], linux.O_RDONLY|linux.O_CLOEXEC, 0)
 		if errno != 0 {
 			// This may fail if this process was migrated out of
 			// the cgroup found by FindCPU and that cgroup has been
@@ -122,7 +122,7 @@ func OpenCPU(scratch []byte) (CPU, error) {
 
 		n2 = copy(base[n:], v1PeriodFile)
 		path = base[:n+n2]
-		periodFD, errno := syscall.Open(&path[0], syscall.O_RDONLY|syscall.O_CLOEXEC, 0)
+		periodFD, errno := linux.Open(&path[0], linux.O_RDONLY|linux.O_CLOEXEC, 0)
 		if errno != 0 {
 			// This may fail if this process was migrated out of
 			// the cgroup found by FindCPU and that cgroup has been
@@ -139,7 +139,7 @@ func OpenCPU(scratch []byte) (CPU, error) {
 	case 2:
 		n2 := copy(base[n:], v2MaxFile)
 		path := base[:n+n2]
-		maxFD, errno := syscall.Open(&path[0], syscall.O_RDONLY|syscall.O_CLOEXEC, 0)
+		maxFD, errno := linux.Open(&path[0], linux.O_RDONLY|linux.O_CLOEXEC, 0)
 		if errno != 0 {
 			// This may fail if this process was migrated out of
 			// the cgroup found by FindCPU and that cgroup has been
@@ -200,7 +200,7 @@ func readV1Number(fd int) (int64, error) {
 	//
 	// Always read from the beginning of the file to get a fresh value.
 	var b [64]byte
-	n, errno := syscall.Pread(fd, b[:], 0)
+	n, errno := linux.Pread(fd, b[:], 0)
 	if errno != 0 {
 		return 0, errSyscallFailed
 	}
@@ -248,7 +248,7 @@ func readV2Limit(fd int) (float64, bool, error) {
 	//
 	// Always read from the beginning of the file to get a fresh value.
 	var b [64]byte
-	n, errno := syscall.Pread(fd, b[:], 0)
+	n, errno := linux.Pread(fd, b[:], 0)
 	if errno != 0 {
 		return 0, false, errSyscallFailed
 	}
@@ -345,8 +345,8 @@ func FindCPU(out []byte, scratch []byte) (int, Version, error) {
 // Returns ErrNoCgroup if the process is not in a CPU cgroup.
 func FindCPURelativePath(out []byte, scratch []byte) (int, Version, error) {
 	path := []byte("/proc/self/cgroup\x00")
-	fd, errno := syscall.Open(&path[0], syscall.O_RDONLY|syscall.O_CLOEXEC, 0)
+	fd, errno := linux.Open(&path[0], linux.O_RDONLY|linux.O_CLOEXEC, 0)
-	if errno == syscall.ENOENT {
+	if errno == linux.ENOENT {
 		return 0, 0, ErrNoCgroup
 	} else if errno != 0 {
 		return 0, 0, errSyscallFailed
@@ -354,13 +354,13 @@ func FindCPURelativePath(out []byte, scratch []byte) (int, Version, error) {
 
 	// The relative path always starts with /, so we can directly append it
 	// to the mount point.
-	n, version, err := parseCPURelativePath(fd, syscall.Read, out[:], scratch)
+	n, version, err := parseCPURelativePath(fd, linux.Read, out[:], scratch)
 	if err != nil {
-		syscall.Close(fd)
+		linux.Close(fd)
 		return 0, 0, err
 	}
 
-	syscall.Close(fd)
+	linux.Close(fd)
 	return n, version, nil
 }
 
@@ -489,19 +489,19 @@ func FindCPUMountPoint(out []byte, scratch []byte) (int, error) {
 	checkBufferSize(scratch, ParseSize)
 
 	path := []byte("/proc/self/mountinfo\x00")
-	fd, errno := syscall.Open(&path[0], syscall.O_RDONLY|syscall.O_CLOEXEC, 0)
+	fd, errno := linux.Open(&path[0], linux.O_RDONLY|linux.O_CLOEXEC, 0)
-	if errno == syscall.ENOENT {
+	if errno == linux.ENOENT {
 		return 0, ErrNoCgroup
 	} else if errno != 0 {
 		return 0, errSyscallFailed
 	}
 
-	n, err := parseCPUMount(fd, syscall.Read, out, scratch)
+	n, err := parseCPUMount(fd, linux.Read, out, scratch)
 	if err != nil {
-		syscall.Close(fd)
+		linux.Close(fd)
 		return 0, err
 	}
-	syscall.Close(fd)
+	linux.Close(fd)
 
 	return n, nil
 }

src/internal/runtime/cgroup/line_reader.go

@@ -55,7 +55,7 @@ type lineReader struct {
 // remainder of the line skipped. See next for more details.
 //
 // read is the function used to read more bytes from fd. This is usually
-// internal/runtime/syscall.Read. Note that this follows syscall semantics (not
+// internal/runtime/syscall/linux.Read. Note that this follows syscall semantics (not
 // io.Reader), so EOF is indicated with n=0, errno=0.
 func newLineReader(fd int, scratch []byte, read func(fd int, b []byte) (n int, errno uintptr)) *lineReader {
 	return &lineReader{

src/internal/runtime/syscall/linux/defs_linux.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package syscall
+package linux
 
 const (
 	AT_FDCWD = -0x64

src/internal/runtime/syscall/linux/defs_linux_386.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package syscall
+package linux
 
 const (
 	SYS_CLOSE         = 6

src/internal/runtime/syscall/linux/defs_linux_amd64.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package syscall
+package linux
 
 const (
 	SYS_CLOSE         = 3

src/internal/runtime/syscall/linux/defs_linux_arm.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package syscall
+package linux
 
 const (
 	SYS_CLOSE         = 6

src/internal/runtime/syscall/linux/defs_linux_arm64.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package syscall
+package linux
 
 const (
 	SYS_CLOSE         = 57

src/internal/runtime/syscall/linux/defs_linux_loong64.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package syscall
+package linux
 
 const (
 	SYS_CLOSE         = 57

src/internal/runtime/syscall/linux/defs_linux_mips64x.go

@@ -4,7 +4,7 @@
 
 //go:build linux && (mips64 || mips64le)
 
-package syscall
+package linux
 
 const (
 	SYS_CLOSE         = 5003

src/internal/runtime/syscall/linux/defs_linux_mipsx.go

@@ -4,7 +4,7 @@
 
 //go:build linux && (mips || mipsle)
 
-package syscall
+package linux
 
 const (
 	SYS_CLOSE         = 4006

src/internal/runtime/syscall/linux/defs_linux_ppc64x.go

@@ -4,7 +4,7 @@
 
 //go:build linux && (ppc64 || ppc64le)
 
-package syscall
+package linux
 
 const (
 	SYS_CLOSE         = 6

src/internal/runtime/syscall/linux/defs_linux_riscv64.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package syscall
+package linux
 
 const (
 	SYS_CLOSE         = 57

src/internal/runtime/syscall/linux/defs_linux_s390x.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package syscall
+package linux
 
 const (
 	SYS_CLOSE         = 6

src/internal/runtime/syscall/linux/syscall_linux.go

@@ -2,16 +2,15 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Package syscall provides the syscall primitives required for the runtime.
+// Package linux provides the syscall primitives required for the runtime.
-package syscall
+package linux
 
 import (
 	"internal/goarch"
 	"unsafe"
 )
 
-// TODO(https://go.dev/issue/51087): This package is incomplete and currently
+// TODO(https://go.dev/issue/51087): Move remaining syscalls to this package.
-// only contains very minimal support for Linux.
 
 // Syscall6 calls system call number 'num' with arguments a1-6.
 func Syscall6(num, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, errno uintptr)

src/internal/runtime/syscall/linux/syscall_linux_test.go

@@ -2,15 +2,15 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package syscall_test
+package linux_test
 
 import (
-	"internal/runtime/syscall"
+	"internal/runtime/syscall/linux"
 	"testing"
 )
 
 func TestEpollctlErrorSign(t *testing.T) {
-	v := syscall.EpollCtl(-1, 1, -1, &syscall.EpollEvent{})
+	v := linux.EpollCtl(-1, 1, -1, &linux.EpollEvent{})
 
 	const EBADF = 0x09
 	if v != EBADF {

src/runtime/netpoll_epoll.go

@@ -8,7 +8,7 @@ package runtime
 
 import (
 	"internal/runtime/atomic"
-	"internal/runtime/syscall"
+	"internal/runtime/syscall/linux"
 	"unsafe"
 )
 
@@ -20,21 +20,21 @@ var (
 
 func netpollinit() {
 	var errno uintptr
-	epfd, errno = syscall.EpollCreate1(syscall.EPOLL_CLOEXEC)
+	epfd, errno = linux.EpollCreate1(linux.EPOLL_CLOEXEC)
 	if errno != 0 {
 		println("runtime: epollcreate failed with", errno)
 		throw("runtime: netpollinit failed")
 	}
-	efd, errno := syscall.Eventfd(0, syscall.EFD_CLOEXEC|syscall.EFD_NONBLOCK)
+	efd, errno := linux.Eventfd(0, linux.EFD_CLOEXEC|linux.EFD_NONBLOCK)
 	if errno != 0 {
 		println("runtime: eventfd failed with", -errno)
 		throw("runtime: eventfd failed")
 	}
-	ev := syscall.EpollEvent{
+	ev := linux.EpollEvent{
-		Events: syscall.EPOLLIN,
+		Events: linux.EPOLLIN,
 	}
 	*(**uintptr)(unsafe.Pointer(&ev.Data)) = &netpollEventFd
-	errno = syscall.EpollCtl(epfd, syscall.EPOLL_CTL_ADD, efd, &ev)
+	errno = linux.EpollCtl(epfd, linux.EPOLL_CTL_ADD, efd, &ev)
 	if errno != 0 {
 		println("runtime: epollctl failed with", errno)
 		throw("runtime: epollctl failed")
@@ -47,16 +47,16 @@ func netpollIsPollDescriptor(fd uintptr) bool {
 }
 
 func netpollopen(fd uintptr, pd *pollDesc) uintptr {
-	var ev syscall.EpollEvent
+	var ev linux.EpollEvent
-	ev.Events = syscall.EPOLLIN | syscall.EPOLLOUT | syscall.EPOLLRDHUP | syscall.EPOLLET
+	ev.Events = linux.EPOLLIN | linux.EPOLLOUT | linux.EPOLLRDHUP | linux.EPOLLET
 	tp := taggedPointerPack(unsafe.Pointer(pd), pd.fdseq.Load())
 	*(*taggedPointer)(unsafe.Pointer(&ev.Data)) = tp
-	return syscall.EpollCtl(epfd, syscall.EPOLL_CTL_ADD, int32(fd), &ev)
+	return linux.EpollCtl(epfd, linux.EPOLL_CTL_ADD, int32(fd), &ev)
 }
 
 func netpollclose(fd uintptr) uintptr {
-	var ev syscall.EpollEvent
+	var ev linux.EpollEvent
-	return syscall.EpollCtl(epfd, syscall.EPOLL_CTL_DEL, int32(fd), &ev)
+	return linux.EpollCtl(epfd, linux.EPOLL_CTL_DEL, int32(fd), &ev)
 }
 
 func netpollarm(pd *pollDesc, mode int) {
@@ -114,9 +114,9 @@ func netpoll(delay int64) (gList, int32) {
 		// 1e9 ms == ~11.5 days.
 		waitms = 1e9
 	}
-	var events [128]syscall.EpollEvent
+	var events [128]linux.EpollEvent
 retry:
-	n, errno := syscall.EpollWait(epfd, events[:], int32(len(events)), waitms)
+	n, errno := linux.EpollWait(epfd, events[:], int32(len(events)), waitms)
 	if errno != 0 {
 		if errno != _EINTR {
 			println("runtime: epollwait on fd", epfd, "failed with", errno)
@@ -138,7 +138,7 @@ retry:
 		}
 
 		if *(**uintptr)(unsafe.Pointer(&ev.Data)) == &netpollEventFd {
-			if ev.Events != syscall.EPOLLIN {
+			if ev.Events != linux.EPOLLIN {
 				println("runtime: netpoll: eventfd ready for", ev.Events)
 				throw("runtime: netpoll: eventfd ready for something unexpected")
 			}
@@ -156,10 +156,10 @@ retry:
 		}
 
 		var mode int32
-		if ev.Events&(syscall.EPOLLIN|syscall.EPOLLRDHUP|syscall.EPOLLHUP|syscall.EPOLLERR) != 0 {
+		if ev.Events&(linux.EPOLLIN|linux.EPOLLRDHUP|linux.EPOLLHUP|linux.EPOLLERR) != 0 {
 			mode += 'r'
 		}
-		if ev.Events&(syscall.EPOLLOUT|syscall.EPOLLHUP|syscall.EPOLLERR) != 0 {
+		if ev.Events&(linux.EPOLLOUT|linux.EPOLLHUP|linux.EPOLLERR) != 0 {
 			mode += 'w'
 		}
 		if mode != 0 {
@@ -167,7 +167,7 @@ retry:
 			pd := (*pollDesc)(tp.pointer())
 			tag := tp.tag()
 			if pd.fdseq.Load() == tag {
-				pd.setEventErr(ev.Events == syscall.EPOLLERR, tag)
+				pd.setEventErr(ev.Events == linux.EPOLLERR, tag)
 				delta += netpollready(&toRun, pd, mode)
 			}
 		}

src/runtime/os_linux.go

@@ -9,7 +9,7 @@ import (
 	"internal/goarch"
 	"internal/runtime/atomic"
 	"internal/runtime/strconv"
-	"internal/runtime/syscall"
+	"internal/runtime/syscall/linux"
 	"unsafe"
 )
 
@@ -470,7 +470,7 @@ func pipe2(flags int32) (r, w int32, errno int32)
 
 //go:nosplit
 func fcntl(fd, cmd, arg int32) (ret int32, errno int32) {
-	r, _, err := syscall.Syscall6(syscall.SYS_FCNTL, uintptr(fd), uintptr(cmd), uintptr(arg), 0, 0, 0)
+	r, _, err := linux.Syscall6(linux.SYS_FCNTL, uintptr(fd), uintptr(cmd), uintptr(arg), 0, 0, 0)
 	return int32(r), int32(err)
 }
 
@@ -773,7 +773,7 @@ func syscall_runtime_doAllThreadsSyscall(trap, a1, a2, a3, a4, a5, a6 uintptr) (
 	// ensuring all threads execute system calls from multiple calls in the
 	// same order.
 
-	r1, r2, errno := syscall.Syscall6(trap, a1, a2, a3, a4, a5, a6)
+	r1, r2, errno := linux.Syscall6(trap, a1, a2, a3, a4, a5, a6)
 	if GOARCH == "ppc64" || GOARCH == "ppc64le" {
 		// TODO(https://go.dev/issue/51192 ): ppc64 doesn't use r2.
 		r2 = 0
@@ -884,7 +884,7 @@ func runPerThreadSyscall() {
 	}
 
 	args := perThreadSyscall
-	r1, r2, errno := syscall.Syscall6(args.trap, args.a1, args.a2, args.a3, args.a4, args.a5, args.a6)
+	r1, r2, errno := linux.Syscall6(args.trap, args.a1, args.a2, args.a3, args.a4, args.a5, args.a6)
 	if GOARCH == "ppc64" || GOARCH == "ppc64le" {
 		// TODO(https://go.dev/issue/51192 ): ppc64 doesn't use r2.
 		r2 = 0
@@ -923,6 +923,6 @@ func (c *sigctxt) sigFromSeccomp() bool {
 
 //go:nosplit
 func mprotect(addr unsafe.Pointer, n uintptr, prot int32) (ret int32, errno int32) {
-	r, _, err := syscall.Syscall6(syscall.SYS_MPROTECT, uintptr(addr), n, uintptr(prot), 0, 0, 0)
+	r, _, err := linux.Syscall6(linux.SYS_MPROTECT, uintptr(addr), n, uintptr(prot), 0, 0, 0)
 	return int32(r), int32(err)
 }

src/runtime/os_linux_riscv64.go

@@ -5,7 +5,7 @@
 package runtime
 
 import (
-	"internal/runtime/syscall"
+	"internal/runtime/syscall/linux"
 	"unsafe"
 )
 
@@ -32,6 +32,6 @@ func internal_cpu_riscvHWProbe(pairs []riscvHWProbePairs, flags uint) bool {
 	}
 	// Passing in a cpuCount of 0 and a cpu of nil ensures that only extensions supported by all the
 	// cores are returned, which is the behaviour we want in internal/cpu.
-	_, _, e1 := syscall.Syscall6(sys_RISCV_HWPROBE, uintptr(unsafe.Pointer(&pairs[0])), uintptr(len(pairs)), uintptr(0), uintptr(unsafe.Pointer(nil)), uintptr(flags), 0)
+	_, _, e1 := linux.Syscall6(sys_RISCV_HWPROBE, uintptr(unsafe.Pointer(&pairs[0])), uintptr(len(pairs)), uintptr(0), uintptr(unsafe.Pointer(nil)), uintptr(flags), 0)
 	return e1 == 0
 }

src/runtime/set_vma_name_linux.go

@@ -8,7 +8,7 @@ package runtime
 
 import (
 	"internal/runtime/atomic"
-	"internal/runtime/syscall"
+	"internal/runtime/syscall/linux"
 	"unsafe"
 )
 
@@ -24,7 +24,7 @@ func setVMAName(start unsafe.Pointer, length uintptr, name string) {
 	n := copy(sysName[:], " Go: ")
 	copy(sysName[n:79], name) // leave final byte zero
 
-	_, _, err := syscall.Syscall6(syscall.SYS_PRCTL, syscall.PR_SET_VMA, syscall.PR_SET_VMA_ANON_NAME, uintptr(start), length, uintptr(unsafe.Pointer(&sysName[0])), 0)
+	_, _, err := linux.Syscall6(linux.SYS_PRCTL, linux.PR_SET_VMA, linux.PR_SET_VMA_ANON_NAME, uintptr(start), length, uintptr(unsafe.Pointer(&sysName[0])), 0)
 	if err == _EINVAL {
 		prSetVMAUnsupported.Store(true)
 	}

src/syscall/syscall_linux.go

@@ -13,7 +13,7 @@ package syscall
 
 import (
 	"internal/itoa"
-	runtimesyscall "internal/runtime/syscall"
+	"internal/runtime/syscall/linux"
 	"runtime"
 	"slices"
 	"unsafe"
@@ -62,7 +62,7 @@ func RawSyscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno) {
 //go:linkname RawSyscall6
 func RawSyscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno) {
 	var errno uintptr
-	r1, r2, errno = runtimesyscall.Syscall6(trap, a1, a2, a3, a4, a5, a6)
+	r1, r2, errno = linux.Syscall6(trap, a1, a2, a3, a4, a5, a6)
 	err = Errno(errno)
 	return
 }