4 files changed, 43 insertions, 10 deletions
diff --git a/pkg/sentry/platform/ptrace/subprocess.go b/pkg/sentry/platform/ptrace/subprocess.go
index 4f8f9c5d9..9f0ecfbe4 100644
--- a/pkg/sentry/platform/ptrace/subprocess.go
+++ b/pkg/sentry/platform/ptrace/subprocess.go
@@ -267,7 +267,7 @@ func (s *subprocess) newThread() *thread {
 
 // attach attaches to the thread.
 func (t *thread) attach() {
-	if _, _, errno := syscall.RawSyscall(syscall.SYS_PTRACE, syscall.PTRACE_ATTACH, uintptr(t.tid), 0); errno != 0 {
+	if _, _, errno := syscall.RawSyscall6(syscall.SYS_PTRACE, syscall.PTRACE_ATTACH, uintptr(t.tid), 0, 0, 0, 0); errno != 0 {
 		panic(fmt.Sprintf("unable to attach: %v", errno))
 	}
 
@@ -417,7 +417,7 @@ func (t *thread) syscall(regs *syscall.PtraceRegs) (uintptr, error) {
 
 	for {
 		// Execute the syscall instruction.
-		if _, _, errno := syscall.RawSyscall(syscall.SYS_PTRACE, syscall.PTRACE_SYSCALL, uintptr(t.tid), 0); errno != 0 {
+		if _, _, errno := syscall.RawSyscall6(syscall.SYS_PTRACE, syscall.PTRACE_SYSCALL, uintptr(t.tid), 0, 0, 0, 0); errno != 0 {
 			panic(fmt.Sprintf("ptrace syscall-enter failed: %v", errno))
 		}
 
@@ -435,7 +435,7 @@ func (t *thread) syscall(regs *syscall.PtraceRegs) (uintptr, error) {
 	}
 
 	// Complete the actual system call.
-	if _, _, errno := syscall.RawSyscall(syscall.SYS_PTRACE, syscall.PTRACE_SYSCALL, uintptr(t.tid), 0); errno != 0 {
+	if _, _, errno := syscall.RawSyscall6(syscall.SYS_PTRACE, syscall.PTRACE_SYSCALL, uintptr(t.tid), 0, 0, 0, 0); errno != 0 {
 		panic(fmt.Sprintf("ptrace syscall-enter failed: %v", errno))
 	}
 
@@ -526,17 +526,17 @@ func (s *subprocess) switchToApp(c *context, ac arch.Context) bool {
 	for {
 		// Start running until the next system call.
 		if isSingleStepping(regs) {
-			if _, _, errno := syscall.RawSyscall(
+			if _, _, errno := syscall.RawSyscall6(
 				syscall.SYS_PTRACE,
 				syscall.PTRACE_SYSEMU_SINGLESTEP,
-				uintptr(t.tid), 0); errno != 0 {
+				uintptr(t.tid), 0, 0, 0, 0); errno != 0 {
 				panic(fmt.Sprintf("ptrace sysemu failed: %v", errno))
 			}
 		} else {
-			if _, _, errno := syscall.RawSyscall(
+			if _, _, errno := syscall.RawSyscall6(
 				syscall.SYS_PTRACE,
 				syscall.PTRACE_SYSEMU,
-				uintptr(t.tid), 0); errno != 0 {
+				uintptr(t.tid), 0, 0, 0, 0); errno != 0 {
 				panic(fmt.Sprintf("ptrace sysemu failed: %v", errno))
 			}
 		}
diff --git a/pkg/sentry/platform/ptrace/subprocess_linux.go b/pkg/sentry/platform/ptrace/subprocess_linux.go
index f09b0b3d0..c075b5f91 100644
--- a/pkg/sentry/platform/ptrace/subprocess_linux.go
+++ b/pkg/sentry/platform/ptrace/subprocess_linux.go
@@ -53,7 +53,7 @@ func probeSeccomp() bool {
 
 	for {
 		// Attempt an emulation.
-		if _, _, errno := syscall.RawSyscall(syscall.SYS_PTRACE, syscall.PTRACE_SYSEMU, uintptr(t.tid), 0); errno != 0 {
+		if _, _, errno := syscall.RawSyscall6(syscall.SYS_PTRACE, syscall.PTRACE_SYSEMU, uintptr(t.tid), 0, 0, 0, 0); errno != 0 {
 			panic(fmt.Sprintf("ptrace syscall-enter failed: %v", errno))
 		}
 
@@ -266,7 +266,7 @@ func attachedThread(flags uintptr, defaultAction linux.BPFAction) (*thread, erro
 
 	// Enable cpuid-faulting; this may fail on older kernels or hardware,
 	// so we just disregard the result. Host CPUID will be enabled.
-	syscall.RawSyscall(syscall.SYS_ARCH_PRCTL, linux.ARCH_SET_CPUID, 0, 0)
+	syscall.RawSyscall6(syscall.SYS_ARCH_PRCTL, linux.ARCH_SET_CPUID, 0, 0, 0, 0, 0)
 
 	// Call the stub; should not return.
 	stubCall(stubStart, ppid)
diff --git a/pkg/sentry/syscalls/linux/linux64.go b/pkg/sentry/syscalls/linux/linux64.go
index 18d24ab61..61acd0abd 100644
--- a/pkg/sentry/syscalls/linux/linux64.go
+++ b/pkg/sentry/syscalls/linux/linux64.go
@@ -232,7 +232,7 @@ var AMD64 = &kernel.SyscallTable{
 		184: syscalls.Error("tuxcall", syserror.ENOSYS, "Not implemented in Linux.", nil),
 		185: syscalls.Error("security", syserror.ENOSYS, "Not implemented in Linux.", nil),
 		186: syscalls.Supported("gettid", Gettid),
-		187: syscalls.ErrorWithEvent("readahead", syserror.ENOSYS, "", []string{"gvisor.dev/issue/261"}), // TODO(b/29351341)
+		187: syscalls.Supported("readahead", Readahead),
 		188: syscalls.Error("setxattr", syserror.ENOTSUP, "Requires filesystem support.", nil),
 		189: syscalls.Error("lsetxattr", syserror.ENOTSUP, "Requires filesystem support.", nil),
 		190: syscalls.Error("fsetxattr", syserror.ENOTSUP, "Requires filesystem support.", nil),
diff --git a/pkg/sentry/syscalls/linux/sys_read.go b/pkg/sentry/syscalls/linux/sys_read.go
index 3ab54271c..cd31e0649 100644
--- a/pkg/sentry/syscalls/linux/sys_read.go
+++ b/pkg/sentry/syscalls/linux/sys_read.go
@@ -72,6 +72,39 @@ func Read(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallC
 	return uintptr(n), nil, handleIOError(t, n != 0, err, kernel.ERESTARTSYS, "read", file)
 }
 
+// Readahead implements readahead(2).
+func Readahead(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	fd := args[0].Int()
+	offset := args[1].Int64()
+	size := args[2].SizeT()
+
+	file := t.GetFile(fd)
+	if file == nil {
+		return 0, nil, syserror.EBADF
+	}
+	defer file.DecRef()
+
+	// Check that the file is readable.
+	if !file.Flags().Read {
+		return 0, nil, syserror.EBADF
+	}
+
+	// Check that the size is valid.
+	if int(size) < 0 {
+		return 0, nil, syserror.EINVAL
+	}
+
+	// Check that the offset is legitimate.
+	if offset < 0 {
+		return 0, nil, syserror.EINVAL
+	}
+
+	// Return EINVAL; if the underlying file type does not support readahead,
+	// then Linux will return EINVAL to indicate as much. In the future, we
+	// may extend this function to actually support readahead hints.
+	return 0, nil, syserror.EINVAL
+}
+
 // Pread64 implements linux syscall pread64(2).
 func Pread64(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
 	fd := args[0].Int()