Port eventfd to VFS2.

And move sys_timerfd.go to just timerfd.go for consistency.

Updates #1475.

PiperOrigin-RevId: 309835029

4 files changed, 63 insertions, 3 deletions

diff --git a/pkg/sentry/syscalls/linux/vfs2/BUILD b/pkg/sentry/syscalls/linux/vfs2/BUILD
index f6fb0f219..ffca627d4 100644
--- a/pkg/sentry/syscalls/linux/vfs2/BUILD
+++ b/pkg/sentry/syscalls/linux/vfs2/BUILD
@@ -6,6 +6,7 @@ go_library(
     name = "vfs2",
     srcs = [
         "epoll.go",
+        "eventfd.go",
         "execve.go",
         "fd.go",
         "filesystem.go",
@@ -26,7 +27,7 @@ go_library(
         "stat_amd64.go",
         "stat_arm64.go",
         "sync.go",
-        "sys_timerfd.go",
+        "timerfd.go",
         "xattr.go",
     ],
     marshal = True,
diff --git a/pkg/sentry/syscalls/linux/vfs2/eventfd.go b/pkg/sentry/syscalls/linux/vfs2/eventfd.go
new file mode 100644
index 000000000..bd2194972
--- /dev/null
+++ b/pkg/sentry/syscalls/linux/vfs2/eventfd.go
@@ -0,0 +1,59 @@
+// Copyright 2018 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package vfs2
+
+import (
+	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/sentry/arch"
+	"gvisor.dev/gvisor/pkg/sentry/kernel"
+	"gvisor.dev/gvisor/pkg/syserror"
+)
+
+// Eventfd2 implements linux syscall eventfd2(2).
+func Eventfd2(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	initVal := uint64(args[0].Uint())
+	flags := uint(args[1].Uint())
+	allOps := uint(linux.EFD_SEMAPHORE | linux.EFD_NONBLOCK | linux.EFD_CLOEXEC)
+
+	if flags & ^allOps != 0 {
+		return 0, nil, syserror.EINVAL
+	}
+
+	fileFlags := uint32(linux.O_RDWR)
+	if flags&linux.EFD_NONBLOCK != 0 {
+		fileFlags |= linux.O_NONBLOCK
+	}
+	semMode := flags&linux.EFD_SEMAPHORE != 0
+	eventfd, err := t.Kernel().VFS().NewEventFD(initVal, semMode, fileFlags)
+	if err != nil {
+		return 0, nil, err
+	}
+	defer eventfd.DecRef()
+
+	fd, err := t.NewFDFromVFS2(0, eventfd, kernel.FDFlags{
+		CloseOnExec: flags&linux.EFD_CLOEXEC != 0,
+	})
+	if err != nil {
+		return 0, nil, err
+	}
+
+	return uintptr(fd), nil, nil
+}
+
+// Eventfd implements linux syscall eventfd(2).
+func Eventfd(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	args[1].Value = 0
+	return Eventfd2(t, args)
+}
diff --git a/pkg/sentry/syscalls/linux/vfs2/linux64_override_amd64.go b/pkg/sentry/syscalls/linux/vfs2/linux64_override_amd64.go
index 74920f785..074f58e5d 100644
--- a/pkg/sentry/syscalls/linux/vfs2/linux64_override_amd64.go
+++ b/pkg/sentry/syscalls/linux/vfs2/linux64_override_amd64.go
@@ -141,14 +141,14 @@ func Override(table map[uintptr]kernel.Syscall) {
 	table[281] = syscalls.Supported("epoll_pwait", EpollPwait)
 	delete(table, 282) // signalfd
 	table[283] = syscalls.Supported("timerfd_create", TimerfdCreate)
-	delete(table, 284) // eventfd
+	table[284] = syscalls.Supported("eventfd", Eventfd)
 	delete(table, 285) // fallocate
 	table[286] = syscalls.Supported("timerfd_settime", TimerfdSettime)
 	table[287] = syscalls.Supported("timerfd_gettime", TimerfdGettime)
 	// TODO(gvisor.dev/issue/1485): Port all socket variants to VFS2.
 	table[288] = syscalls.PartiallySupported("accept4", Accept4, "In process of porting socket syscalls to VFS2.", nil)
 	delete(table, 289) // signalfd4
-	delete(table, 290) // eventfd2
+	table[290] = syscalls.Supported("eventfd2", Eventfd2)
 	table[291] = syscalls.Supported("epoll_create1", EpollCreate1)
 	table[292] = syscalls.Supported("dup3", Dup3)
 	table[293] = syscalls.Supported("pipe2", Pipe2)
diff --git a/pkg/sentry/syscalls/linux/vfs2/sys_timerfd.go b/pkg/sentry/syscalls/linux/vfs2/timerfd.go
index 7938a5249..7938a5249 100644
--- a/pkg/sentry/syscalls/linux/vfs2/sys_timerfd.go
+++ b/pkg/sentry/syscalls/linux/vfs2/timerfd.go