Add introspection for Linux/AMD64 syscalls

Adds simple introspection for syscall compatibility information to Linux/AMD64.
Syscalls registered in the syscall table now have associated metadata like
name, support level, notes, and URLs to relevant issues.

Syscall information can be exported as a table, JSON, or CSV using the new
'runsc help syscalls' command. Users can use this info to debug and get info
on the compatibility of the version of runsc they are running or to generate
documentation.

PiperOrigin-RevId: 252558304

1 files changed, 74 insertions, 14 deletions

diff --git a/pkg/sentry/syscalls/syscalls.go b/pkg/sentry/syscalls/syscalls.go
index 5d10b3824..48c114232 100644
--- a/pkg/sentry/syscalls/syscalls.go
+++ b/pkg/sentry/syscalls/syscalls.go
@@ -25,37 +25,97 @@
 package syscalls
 
 import (
+	"fmt"
+	"syscall"
+
 	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/arch"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel"
 	"gvisor.googlesource.com/gvisor/pkg/syserror"
 )
 
+// Supported returns a syscall that is fully supported.
+func Supported(name string, fn kernel.SyscallFn) kernel.Syscall {
+	return kernel.Syscall{
+		Name:         name,
+		Fn:           fn,
+		SupportLevel: kernel.SupportFull,
+		Note:         "Full Support",
+	}
+}
+
+// Undocumented returns a syscall that is undocumented.
+func Undocumented(name string, fn kernel.SyscallFn) kernel.Syscall {
+	return kernel.Syscall{
+		Name:         name,
+		Fn:           fn,
+		SupportLevel: kernel.SupportUndocumented,
+	}
+}
+
+// PartiallySupported returns a syscall that has a partial implementation.
+func PartiallySupported(name string, fn kernel.SyscallFn, note string, urls []string) kernel.Syscall {
+	return kernel.Syscall{
+		Name:         name,
+		Fn:           fn,
+		SupportLevel: kernel.SupportPartial,
+		Note:         note,
+		URLs:         urls,
+	}
+}
+
 // Error returns a syscall handler that will always give the passed error.
-func Error(err error) kernel.SyscallFn {
-	return func(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
-		return 0, nil, err
+func Error(name string, err syscall.Errno, note string, urls []string) kernel.Syscall {
+	if note != "" {
+		note = note + "; "
+	}
+	return kernel.Syscall{
+		Name: name,
+		Fn: func(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+			return 0, nil, err
+		},
+		SupportLevel: kernel.SupportUnimplemented,
+		Note:         fmt.Sprintf("%sReturns %q", note, err.Error()),
+		URLs:         urls,
 	}
 }
 
 // ErrorWithEvent gives a syscall function that sends an unimplemented
 // syscall event via the event channel and returns the passed error.
-func ErrorWithEvent(err error) kernel.SyscallFn {
-	return func(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
-		t.Kernel().EmitUnimplementedEvent(t)
-		return 0, nil, err
+func ErrorWithEvent(name string, err syscall.Errno, note string, urls []string) kernel.Syscall {
+	if note != "" {
+		note = note + "; "
+	}
+	return kernel.Syscall{
+		Name: name,
+		Fn: func(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+			t.Kernel().EmitUnimplementedEvent(t)
+			return 0, nil, err
+		},
+		SupportLevel: kernel.SupportUnimplemented,
+		Note:         fmt.Sprintf("%sReturns %q", note, err.Error()),
+		URLs:         urls,
 	}
 }
 
 // CapError gives a syscall function that checks for capability c.  If the task
 // has the capability, it returns ENOSYS, otherwise EPERM. To unprivileged
 // tasks, it will seem like there is an implementation.
-func CapError(c linux.Capability) kernel.SyscallFn {
-	return func(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
-		if !t.HasCapability(c) {
-			return 0, nil, syserror.EPERM
-		}
-		t.Kernel().EmitUnimplementedEvent(t)
-		return 0, nil, syserror.ENOSYS
+func CapError(name string, c linux.Capability, note string, urls []string) kernel.Syscall {
+	if note != "" {
+		note = note + "; "
+	}
+	return kernel.Syscall{
+		Name: name,
+		Fn: func(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+			if !t.HasCapability(c) {
+				return 0, nil, syserror.EPERM
+			}
+			t.Kernel().EmitUnimplementedEvent(t)
+			return 0, nil, syserror.ENOSYS
+		},
+		SupportLevel: kernel.SupportUnimplemented,
+		Note:         fmt.Sprintf("%sReturns %q if the process does not have %s; %q otherwise", note, syserror.EPERM, c.String(), syserror.ENOSYS),
+		URLs:         urls,
 	}
 }