Merge release-20201208.0-95-gfc153750e (automated)

5 files changed, 525 insertions, 525 deletions

diff --git a/pkg/sentry/arch/arch_abi_autogen_unsafe.go b/pkg/sentry/arch/arch_abi_autogen_unsafe.go
index 2ddabb10b..fe68f921d 100644
--- a/pkg/sentry/arch/arch_abi_autogen_unsafe.go
+++ b/pkg/sentry/arch/arch_abi_autogen_unsafe.go
@@ -23,53 +23,71 @@ var _ marshal.Marshallable = (*SignalStack)(nil)
 var _ marshal.Marshallable = (*linux.SignalSet)(nil)
 
 // SizeBytes implements marshal.Marshallable.SizeBytes.
-func (s *SignalStack) SizeBytes() int {
-    return 24
+func (s *SignalAct) SizeBytes() int {
+    return 24 +
+        (*linux.SignalSet)(nil).SizeBytes()
 }
 
 // MarshalBytes implements marshal.Marshallable.MarshalBytes.
-func (s *SignalStack) MarshalBytes(dst []byte) {
-    usermem.ByteOrder.PutUint64(dst[:8], uint64(s.Addr))
+func (s *SignalAct) MarshalBytes(dst []byte) {
+    usermem.ByteOrder.PutUint64(dst[:8], uint64(s.Handler))
     dst = dst[8:]
-    usermem.ByteOrder.PutUint32(dst[:4], uint32(s.Flags))
-    dst = dst[4:]
-    // Padding: dst[:sizeof(uint32)] ~= uint32(0)
-    dst = dst[4:]
-    usermem.ByteOrder.PutUint64(dst[:8], uint64(s.Size))
+    usermem.ByteOrder.PutUint64(dst[:8], uint64(s.Flags))
     dst = dst[8:]
+    usermem.ByteOrder.PutUint64(dst[:8], uint64(s.Restorer))
+    dst = dst[8:]
+    s.Mask.MarshalBytes(dst[:s.Mask.SizeBytes()])
+    dst = dst[s.Mask.SizeBytes():]
 }
 
 // UnmarshalBytes implements marshal.Marshallable.UnmarshalBytes.
-func (s *SignalStack) UnmarshalBytes(src []byte) {
-    s.Addr = uint64(usermem.ByteOrder.Uint64(src[:8]))
+func (s *SignalAct) UnmarshalBytes(src []byte) {
+    s.Handler = uint64(usermem.ByteOrder.Uint64(src[:8]))
     src = src[8:]
-    s.Flags = uint32(usermem.ByteOrder.Uint32(src[:4]))
-    src = src[4:]
-    // Padding: var _ uint32 ~= src[:sizeof(uint32)]
-    src = src[4:]
-    s.Size = uint64(usermem.ByteOrder.Uint64(src[:8]))
+    s.Flags = uint64(usermem.ByteOrder.Uint64(src[:8]))
+    src = src[8:]
+    s.Restorer = uint64(usermem.ByteOrder.Uint64(src[:8]))
     src = src[8:]
+    s.Mask.UnmarshalBytes(src[:s.Mask.SizeBytes()])
+    src = src[s.Mask.SizeBytes():]
 }
 
 // Packed implements marshal.Marshallable.Packed.
 //go:nosplit
-func (s *SignalStack) Packed() bool {
-    return true
+func (s *SignalAct) Packed() bool {
+    return s.Mask.Packed()
 }
 
 // MarshalUnsafe implements marshal.Marshallable.MarshalUnsafe.
-func (s *SignalStack) MarshalUnsafe(dst []byte) {
-    safecopy.CopyIn(dst, unsafe.Pointer(s))
+func (s *SignalAct) MarshalUnsafe(dst []byte) {
+    if s.Mask.Packed() {
+        safecopy.CopyIn(dst, unsafe.Pointer(s))
+    } else {
+        // Type SignalAct doesn't have a packed layout in memory, fallback to MarshalBytes.
+        s.MarshalBytes(dst)
+    }
 }
 
 // UnmarshalUnsafe implements marshal.Marshallable.UnmarshalUnsafe.
-func (s *SignalStack) UnmarshalUnsafe(src []byte) {
-    safecopy.CopyOut(unsafe.Pointer(s), src)
+func (s *SignalAct) UnmarshalUnsafe(src []byte) {
+    if s.Mask.Packed() {
+        safecopy.CopyOut(unsafe.Pointer(s), src)
+    } else {
+        // Type SignalAct doesn't have a packed layout in memory, fallback to UnmarshalBytes.
+        s.UnmarshalBytes(src)
+    }
 }
 
 // CopyOutN implements marshal.Marshallable.CopyOutN.
 //go:nosplit
-func (s *SignalStack) CopyOutN(cc marshal.CopyContext, addr usermem.Addr, limit int) (int, error) {
+func (s *SignalAct) CopyOutN(cc marshal.CopyContext, addr usermem.Addr, limit int) (int, error) {
+    if !s.Mask.Packed() {
+        // Type SignalAct doesn't have a packed layout in memory, fall back to MarshalBytes.
+        buf := cc.CopyScratchBuffer(s.SizeBytes()) // escapes: okay.
+        s.MarshalBytes(buf) // escapes: fallback.
+        return cc.CopyOutBytes(addr, buf[:limit]) // escapes: okay.
+    }
+
     // Construct a slice backed by dst's underlying memory.
     var buf []byte
     hdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
@@ -86,13 +104,23 @@ func (s *SignalStack) CopyOutN(cc marshal.CopyContext, addr usermem.Addr, limit
 
 // CopyOut implements marshal.Marshallable.CopyOut.
 //go:nosplit
-func (s *SignalStack) CopyOut(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
+func (s *SignalAct) CopyOut(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
     return s.CopyOutN(cc, addr, s.SizeBytes())
 }
 
 // CopyIn implements marshal.Marshallable.CopyIn.
 //go:nosplit
-func (s *SignalStack) CopyIn(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
+func (s *SignalAct) CopyIn(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
+    if !s.Mask.Packed() {
+        // Type SignalAct doesn't have a packed layout in memory, fall back to UnmarshalBytes.
+        buf := cc.CopyScratchBuffer(s.SizeBytes()) // escapes: okay.
+        length, err := cc.CopyInBytes(addr, buf) // escapes: okay.
+        // Unmarshal unconditionally. If we had a short copy-in, this results in a
+        // partially unmarshalled struct.
+        s.UnmarshalBytes(buf) // escapes: fallback.
+        return length, err
+    }
+
     // Construct a slice backed by dst's underlying memory.
     var buf []byte
     hdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
@@ -108,7 +136,15 @@ func (s *SignalStack) CopyIn(cc marshal.CopyContext, addr usermem.Addr) (int, er
 }
 
 // WriteTo implements io.WriterTo.WriteTo.
-func (s *SignalStack) WriteTo(writer io.Writer) (int64, error) {
+func (s *SignalAct) WriteTo(writer io.Writer) (int64, error) {
+    if !s.Mask.Packed() {
+        // Type SignalAct doesn't have a packed layout in memory, fall back to MarshalBytes.
+        buf := make([]byte, s.SizeBytes())
+        s.MarshalBytes(buf)
+        length, err := writer.Write(buf)
+        return int64(length), err
+    }
+
     // Construct a slice backed by dst's underlying memory.
     var buf []byte
     hdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
@@ -124,62 +160,53 @@ func (s *SignalStack) WriteTo(writer io.Writer) (int64, error) {
 }
 
 // SizeBytes implements marshal.Marshallable.SizeBytes.
-func (s *SignalInfo) SizeBytes() int {
-    return 16 +
-        1*(128-16)
+func (s *SignalStack) SizeBytes() int {
+    return 24
 }
 
 // MarshalBytes implements marshal.Marshallable.MarshalBytes.
-func (s *SignalInfo) MarshalBytes(dst []byte) {
-    usermem.ByteOrder.PutUint32(dst[:4], uint32(s.Signo))
-    dst = dst[4:]
-    usermem.ByteOrder.PutUint32(dst[:4], uint32(s.Errno))
-    dst = dst[4:]
-    usermem.ByteOrder.PutUint32(dst[:4], uint32(s.Code))
+func (s *SignalStack) MarshalBytes(dst []byte) {
+    usermem.ByteOrder.PutUint64(dst[:8], uint64(s.Addr))
+    dst = dst[8:]
+    usermem.ByteOrder.PutUint32(dst[:4], uint32(s.Flags))
     dst = dst[4:]
     // Padding: dst[:sizeof(uint32)] ~= uint32(0)
     dst = dst[4:]
-    for idx := 0; idx < (128-16); idx++ {
-        dst[0] = byte(s.Fields[idx])
-        dst = dst[1:]
-    }
+    usermem.ByteOrder.PutUint64(dst[:8], uint64(s.Size))
+    dst = dst[8:]
 }
 
 // UnmarshalBytes implements marshal.Marshallable.UnmarshalBytes.
-func (s *SignalInfo) UnmarshalBytes(src []byte) {
-    s.Signo = int32(usermem.ByteOrder.Uint32(src[:4]))
-    src = src[4:]
-    s.Errno = int32(usermem.ByteOrder.Uint32(src[:4]))
-    src = src[4:]
-    s.Code = int32(usermem.ByteOrder.Uint32(src[:4]))
+func (s *SignalStack) UnmarshalBytes(src []byte) {
+    s.Addr = uint64(usermem.ByteOrder.Uint64(src[:8]))
+    src = src[8:]
+    s.Flags = uint32(usermem.ByteOrder.Uint32(src[:4]))
     src = src[4:]
     // Padding: var _ uint32 ~= src[:sizeof(uint32)]
     src = src[4:]
-    for idx := 0; idx < (128-16); idx++ {
-        s.Fields[idx] = src[0]
-        src = src[1:]
-    }
+    s.Size = uint64(usermem.ByteOrder.Uint64(src[:8]))
+    src = src[8:]
 }
 
 // Packed implements marshal.Marshallable.Packed.
 //go:nosplit
-func (s *SignalInfo) Packed() bool {
+func (s *SignalStack) Packed() bool {
     return true
 }
 
 // MarshalUnsafe implements marshal.Marshallable.MarshalUnsafe.
-func (s *SignalInfo) MarshalUnsafe(dst []byte) {
+func (s *SignalStack) MarshalUnsafe(dst []byte) {
     safecopy.CopyIn(dst, unsafe.Pointer(s))
 }
 
 // UnmarshalUnsafe implements marshal.Marshallable.UnmarshalUnsafe.
-func (s *SignalInfo) UnmarshalUnsafe(src []byte) {
+func (s *SignalStack) UnmarshalUnsafe(src []byte) {
     safecopy.CopyOut(unsafe.Pointer(s), src)
 }
 
 // CopyOutN implements marshal.Marshallable.CopyOutN.
 //go:nosplit
-func (s *SignalInfo) CopyOutN(cc marshal.CopyContext, addr usermem.Addr, limit int) (int, error) {
+func (s *SignalStack) CopyOutN(cc marshal.CopyContext, addr usermem.Addr, limit int) (int, error) {
     // Construct a slice backed by dst's underlying memory.
     var buf []byte
     hdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
@@ -196,13 +223,13 @@ func (s *SignalInfo) CopyOutN(cc marshal.CopyContext, addr usermem.Addr, limit i
 
 // CopyOut implements marshal.Marshallable.CopyOut.
 //go:nosplit
-func (s *SignalInfo) CopyOut(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
+func (s *SignalStack) CopyOut(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
     return s.CopyOutN(cc, addr, s.SizeBytes())
 }
 
 // CopyIn implements marshal.Marshallable.CopyIn.
 //go:nosplit
-func (s *SignalInfo) CopyIn(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
+func (s *SignalStack) CopyIn(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
     // Construct a slice backed by dst's underlying memory.
     var buf []byte
     hdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
@@ -218,7 +245,7 @@ func (s *SignalInfo) CopyIn(cc marshal.CopyContext, addr usermem.Addr) (int, err
 }
 
 // WriteTo implements io.WriterTo.WriteTo.
-func (s *SignalInfo) WriteTo(writer io.Writer) (int64, error) {
+func (s *SignalStack) WriteTo(writer io.Writer) (int64, error) {
     // Construct a slice backed by dst's underlying memory.
     var buf []byte
     hdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
@@ -234,71 +261,62 @@ func (s *SignalInfo) WriteTo(writer io.Writer) (int64, error) {
 }
 
 // SizeBytes implements marshal.Marshallable.SizeBytes.
-func (s *SignalAct) SizeBytes() int {
-    return 24 +
-        (*linux.SignalSet)(nil).SizeBytes()
+func (s *SignalInfo) SizeBytes() int {
+    return 16 +
+        1*(128-16)
 }
 
 // MarshalBytes implements marshal.Marshallable.MarshalBytes.
-func (s *SignalAct) MarshalBytes(dst []byte) {
-    usermem.ByteOrder.PutUint64(dst[:8], uint64(s.Handler))
-    dst = dst[8:]
-    usermem.ByteOrder.PutUint64(dst[:8], uint64(s.Flags))
-    dst = dst[8:]
-    usermem.ByteOrder.PutUint64(dst[:8], uint64(s.Restorer))
-    dst = dst[8:]
-    s.Mask.MarshalBytes(dst[:s.Mask.SizeBytes()])
-    dst = dst[s.Mask.SizeBytes():]
+func (s *SignalInfo) MarshalBytes(dst []byte) {
+    usermem.ByteOrder.PutUint32(dst[:4], uint32(s.Signo))
+    dst = dst[4:]
+    usermem.ByteOrder.PutUint32(dst[:4], uint32(s.Errno))
+    dst = dst[4:]
+    usermem.ByteOrder.PutUint32(dst[:4], uint32(s.Code))
+    dst = dst[4:]
+    // Padding: dst[:sizeof(uint32)] ~= uint32(0)
+    dst = dst[4:]
+    for idx := 0; idx < (128-16); idx++ {
+        dst[0] = byte(s.Fields[idx])
+        dst = dst[1:]
+    }
 }
 
 // UnmarshalBytes implements marshal.Marshallable.UnmarshalBytes.
-func (s *SignalAct) UnmarshalBytes(src []byte) {
-    s.Handler = uint64(usermem.ByteOrder.Uint64(src[:8]))
-    src = src[8:]
-    s.Flags = uint64(usermem.ByteOrder.Uint64(src[:8]))
-    src = src[8:]
-    s.Restorer = uint64(usermem.ByteOrder.Uint64(src[:8]))
-    src = src[8:]
-    s.Mask.UnmarshalBytes(src[:s.Mask.SizeBytes()])
-    src = src[s.Mask.SizeBytes():]
+func (s *SignalInfo) UnmarshalBytes(src []byte) {
+    s.Signo = int32(usermem.ByteOrder.Uint32(src[:4]))
+    src = src[4:]
+    s.Errno = int32(usermem.ByteOrder.Uint32(src[:4]))
+    src = src[4:]
+    s.Code = int32(usermem.ByteOrder.Uint32(src[:4]))
+    src = src[4:]
+    // Padding: var _ uint32 ~= src[:sizeof(uint32)]
+    src = src[4:]
+    for idx := 0; idx < (128-16); idx++ {
+        s.Fields[idx] = src[0]
+        src = src[1:]
+    }
 }
 
 // Packed implements marshal.Marshallable.Packed.
 //go:nosplit
-func (s *SignalAct) Packed() bool {
-    return s.Mask.Packed()
+func (s *SignalInfo) Packed() bool {
+    return true
 }
 
 // MarshalUnsafe implements marshal.Marshallable.MarshalUnsafe.
-func (s *SignalAct) MarshalUnsafe(dst []byte) {
-    if s.Mask.Packed() {
-        safecopy.CopyIn(dst, unsafe.Pointer(s))
-    } else {
-        // Type SignalAct doesn't have a packed layout in memory, fallback to MarshalBytes.
-        s.MarshalBytes(dst)
-    }
+func (s *SignalInfo) MarshalUnsafe(dst []byte) {
+    safecopy.CopyIn(dst, unsafe.Pointer(s))
 }
 
 // UnmarshalUnsafe implements marshal.Marshallable.UnmarshalUnsafe.
-func (s *SignalAct) UnmarshalUnsafe(src []byte) {
-    if s.Mask.Packed() {
-        safecopy.CopyOut(unsafe.Pointer(s), src)
-    } else {
-        // Type SignalAct doesn't have a packed layout in memory, fallback to UnmarshalBytes.
-        s.UnmarshalBytes(src)
-    }
+func (s *SignalInfo) UnmarshalUnsafe(src []byte) {
+    safecopy.CopyOut(unsafe.Pointer(s), src)
 }
 
 // CopyOutN implements marshal.Marshallable.CopyOutN.
 //go:nosplit
-func (s *SignalAct) CopyOutN(cc marshal.CopyContext, addr usermem.Addr, limit int) (int, error) {
-    if !s.Mask.Packed() {
-        // Type SignalAct doesn't have a packed layout in memory, fall back to MarshalBytes.
-        buf := cc.CopyScratchBuffer(s.SizeBytes()) // escapes: okay.
-        s.MarshalBytes(buf) // escapes: fallback.
-        return cc.CopyOutBytes(addr, buf[:limit]) // escapes: okay.
-    }
-
+func (s *SignalInfo) CopyOutN(cc marshal.CopyContext, addr usermem.Addr, limit int) (int, error) {
     // Construct a slice backed by dst's underlying memory.
     var buf []byte
     hdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
@@ -315,23 +333,13 @@ func (s *SignalAct) CopyOutN(cc marshal.CopyContext, addr usermem.Addr, limit in
 
 // CopyOut implements marshal.Marshallable.CopyOut.
 //go:nosplit
-func (s *SignalAct) CopyOut(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
+func (s *SignalInfo) CopyOut(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
     return s.CopyOutN(cc, addr, s.SizeBytes())
 }
 
 // CopyIn implements marshal.Marshallable.CopyIn.
 //go:nosplit
-func (s *SignalAct) CopyIn(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
-    if !s.Mask.Packed() {
-        // Type SignalAct doesn't have a packed layout in memory, fall back to UnmarshalBytes.
-        buf := cc.CopyScratchBuffer(s.SizeBytes()) // escapes: okay.
-        length, err := cc.CopyInBytes(addr, buf) // escapes: okay.
-        // Unmarshal unconditionally. If we had a short copy-in, this results in a
-        // partially unmarshalled struct.
-        s.UnmarshalBytes(buf) // escapes: fallback.
-        return length, err
-    }
-
+func (s *SignalInfo) CopyIn(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
     // Construct a slice backed by dst's underlying memory.
     var buf []byte
     hdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
@@ -347,15 +355,7 @@ func (s *SignalAct) CopyIn(cc marshal.CopyContext, addr usermem.Addr) (int, erro
 }
 
 // WriteTo implements io.WriterTo.WriteTo.
-func (s *SignalAct) WriteTo(writer io.Writer) (int64, error) {
-    if !s.Mask.Packed() {
-        // Type SignalAct doesn't have a packed layout in memory, fall back to MarshalBytes.
-        buf := make([]byte, s.SizeBytes())
-        s.MarshalBytes(buf)
-        length, err := writer.Write(buf)
-        return int64(length), err
-    }
-
+func (s *SignalInfo) WriteTo(writer io.Writer) (int64, error) {
     // Construct a slice backed by dst's underlying memory.
     var buf []byte
     hdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
diff --git a/pkg/sentry/arch/arch_amd64_abi_autogen_unsafe.go b/pkg/sentry/arch/arch_amd64_abi_autogen_unsafe.go
index 466bf889a..cdbc88377 100644
--- a/pkg/sentry/arch/arch_amd64_abi_autogen_unsafe.go
+++ b/pkg/sentry/arch/arch_amd64_abi_autogen_unsafe.go
@@ -25,6 +25,149 @@ var _ marshal.Marshallable = (*UContext64)(nil)
 var _ marshal.Marshallable = (*linux.SignalSet)(nil)
 
 // SizeBytes implements marshal.Marshallable.SizeBytes.
+func (u *UContext64) SizeBytes() int {
+    return 16 +
+        (*SignalStack)(nil).SizeBytes() +
+        (*SignalContext64)(nil).SizeBytes() +
+        (*linux.SignalSet)(nil).SizeBytes()
+}
+
+// MarshalBytes implements marshal.Marshallable.MarshalBytes.
+func (u *UContext64) MarshalBytes(dst []byte) {
+    usermem.ByteOrder.PutUint64(dst[:8], uint64(u.Flags))
+    dst = dst[8:]
+    usermem.ByteOrder.PutUint64(dst[:8], uint64(u.Link))
+    dst = dst[8:]
+    u.Stack.MarshalBytes(dst[:u.Stack.SizeBytes()])
+    dst = dst[u.Stack.SizeBytes():]
+    u.MContext.MarshalBytes(dst[:u.MContext.SizeBytes()])
+    dst = dst[u.MContext.SizeBytes():]
+    u.Sigset.MarshalBytes(dst[:u.Sigset.SizeBytes()])
+    dst = dst[u.Sigset.SizeBytes():]
+}
+
+// UnmarshalBytes implements marshal.Marshallable.UnmarshalBytes.
+func (u *UContext64) UnmarshalBytes(src []byte) {
+    u.Flags = uint64(usermem.ByteOrder.Uint64(src[:8]))
+    src = src[8:]
+    u.Link = uint64(usermem.ByteOrder.Uint64(src[:8]))
+    src = src[8:]
+    u.Stack.UnmarshalBytes(src[:u.Stack.SizeBytes()])
+    src = src[u.Stack.SizeBytes():]
+    u.MContext.UnmarshalBytes(src[:u.MContext.SizeBytes()])
+    src = src[u.MContext.SizeBytes():]
+    u.Sigset.UnmarshalBytes(src[:u.Sigset.SizeBytes()])
+    src = src[u.Sigset.SizeBytes():]
+}
+
+// Packed implements marshal.Marshallable.Packed.
+//go:nosplit
+func (u *UContext64) Packed() bool {
+    return u.MContext.Packed() && u.Sigset.Packed() && u.Stack.Packed()
+}
+
+// MarshalUnsafe implements marshal.Marshallable.MarshalUnsafe.
+func (u *UContext64) MarshalUnsafe(dst []byte) {
+    if u.MContext.Packed() && u.Sigset.Packed() && u.Stack.Packed() {
+        safecopy.CopyIn(dst, unsafe.Pointer(u))
+    } else {
+        // Type UContext64 doesn't have a packed layout in memory, fallback to MarshalBytes.
+        u.MarshalBytes(dst)
+    }
+}
+
+// UnmarshalUnsafe implements marshal.Marshallable.UnmarshalUnsafe.
+func (u *UContext64) UnmarshalUnsafe(src []byte) {
+    if u.MContext.Packed() && u.Sigset.Packed() && u.Stack.Packed() {
+        safecopy.CopyOut(unsafe.Pointer(u), src)
+    } else {
+        // Type UContext64 doesn't have a packed layout in memory, fallback to UnmarshalBytes.
+        u.UnmarshalBytes(src)
+    }
+}
+
+// CopyOutN implements marshal.Marshallable.CopyOutN.
+//go:nosplit
+func (u *UContext64) CopyOutN(cc marshal.CopyContext, addr usermem.Addr, limit int) (int, error) {
+    if !u.MContext.Packed() && u.Sigset.Packed() && u.Stack.Packed() {
+        // Type UContext64 doesn't have a packed layout in memory, fall back to MarshalBytes.
+        buf := cc.CopyScratchBuffer(u.SizeBytes()) // escapes: okay.
+        u.MarshalBytes(buf) // escapes: fallback.
+        return cc.CopyOutBytes(addr, buf[:limit]) // escapes: okay.
+    }
+
+    // Construct a slice backed by dst's underlying memory.
+    var buf []byte
+    hdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
+    hdr.Data = uintptr(gohacks.Noescape(unsafe.Pointer(u)))
+    hdr.Len = u.SizeBytes()
+    hdr.Cap = u.SizeBytes()
+
+    length, err := cc.CopyOutBytes(addr, buf[:limit]) // escapes: okay.
+    // Since we bypassed the compiler's escape analysis, indicate that u
+    // must live until the use above.
+    runtime.KeepAlive(u) // escapes: replaced by intrinsic.
+    return length, err
+}
+
+// CopyOut implements marshal.Marshallable.CopyOut.
+//go:nosplit
+func (u *UContext64) CopyOut(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
+    return u.CopyOutN(cc, addr, u.SizeBytes())
+}
+
+// CopyIn implements marshal.Marshallable.CopyIn.
+//go:nosplit
+func (u *UContext64) CopyIn(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
+    if !u.MContext.Packed() && u.Sigset.Packed() && u.Stack.Packed() {
+        // Type UContext64 doesn't have a packed layout in memory, fall back to UnmarshalBytes.
+        buf := cc.CopyScratchBuffer(u.SizeBytes()) // escapes: okay.
+        length, err := cc.CopyInBytes(addr, buf) // escapes: okay.
+        // Unmarshal unconditionally. If we had a short copy-in, this results in a
+        // partially unmarshalled struct.
+        u.UnmarshalBytes(buf) // escapes: fallback.
+        return length, err
+    }
+
+    // Construct a slice backed by dst's underlying memory.
+    var buf []byte
+    hdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
+    hdr.Data = uintptr(gohacks.Noescape(unsafe.Pointer(u)))
+    hdr.Len = u.SizeBytes()
+    hdr.Cap = u.SizeBytes()
+
+    length, err := cc.CopyInBytes(addr, buf) // escapes: okay.
+    // Since we bypassed the compiler's escape analysis, indicate that u
+    // must live until the use above.
+    runtime.KeepAlive(u) // escapes: replaced by intrinsic.
+    return length, err
+}
+
+// WriteTo implements io.WriterTo.WriteTo.
+func (u *UContext64) WriteTo(writer io.Writer) (int64, error) {
+    if !u.MContext.Packed() && u.Sigset.Packed() && u.Stack.Packed() {
+        // Type UContext64 doesn't have a packed layout in memory, fall back to MarshalBytes.
+        buf := make([]byte, u.SizeBytes())
+        u.MarshalBytes(buf)
+        length, err := writer.Write(buf)
+        return int64(length), err
+    }
+
+    // Construct a slice backed by dst's underlying memory.
+    var buf []byte
+    hdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
+    hdr.Data = uintptr(gohacks.Noescape(unsafe.Pointer(u)))
+    hdr.Len = u.SizeBytes()
+    hdr.Cap = u.SizeBytes()
+
+    length, err := writer.Write(buf)
+    // Since we bypassed the compiler's escape analysis, indicate that u
+    // must live until the use above.
+    runtime.KeepAlive(u) // escapes: replaced by intrinsic.
+    return int64(length), err
+}
+
+// SizeBytes implements marshal.Marshallable.SizeBytes.
 func (s *SignalContext64) SizeBytes() int {
     return 184 +
         (*linux.SignalSet)(nil).SizeBytes() +
@@ -262,146 +405,3 @@ func (s *SignalContext64) WriteTo(writer io.Writer) (int64, error) {
     return int64(length), err
 }
 
-// SizeBytes implements marshal.Marshallable.SizeBytes.
-func (u *UContext64) SizeBytes() int {
-    return 16 +
-        (*SignalStack)(nil).SizeBytes() +
-        (*SignalContext64)(nil).SizeBytes() +
-        (*linux.SignalSet)(nil).SizeBytes()
-}
-
-// MarshalBytes implements marshal.Marshallable.MarshalBytes.
-func (u *UContext64) MarshalBytes(dst []byte) {
-    usermem.ByteOrder.PutUint64(dst[:8], uint64(u.Flags))
-    dst = dst[8:]
-    usermem.ByteOrder.PutUint64(dst[:8], uint64(u.Link))
-    dst = dst[8:]
-    u.Stack.MarshalBytes(dst[:u.Stack.SizeBytes()])
-    dst = dst[u.Stack.SizeBytes():]
-    u.MContext.MarshalBytes(dst[:u.MContext.SizeBytes()])
-    dst = dst[u.MContext.SizeBytes():]
-    u.Sigset.MarshalBytes(dst[:u.Sigset.SizeBytes()])
-    dst = dst[u.Sigset.SizeBytes():]
-}
-
-// UnmarshalBytes implements marshal.Marshallable.UnmarshalBytes.
-func (u *UContext64) UnmarshalBytes(src []byte) {
-    u.Flags = uint64(usermem.ByteOrder.Uint64(src[:8]))
-    src = src[8:]
-    u.Link = uint64(usermem.ByteOrder.Uint64(src[:8]))
-    src = src[8:]
-    u.Stack.UnmarshalBytes(src[:u.Stack.SizeBytes()])
-    src = src[u.Stack.SizeBytes():]
-    u.MContext.UnmarshalBytes(src[:u.MContext.SizeBytes()])
-    src = src[u.MContext.SizeBytes():]
-    u.Sigset.UnmarshalBytes(src[:u.Sigset.SizeBytes()])
-    src = src[u.Sigset.SizeBytes():]
-}
-
-// Packed implements marshal.Marshallable.Packed.
-//go:nosplit
-func (u *UContext64) Packed() bool {
-    return u.MContext.Packed() && u.Sigset.Packed() && u.Stack.Packed()
-}
-
-// MarshalUnsafe implements marshal.Marshallable.MarshalUnsafe.
-func (u *UContext64) MarshalUnsafe(dst []byte) {
-    if u.MContext.Packed() && u.Sigset.Packed() && u.Stack.Packed() {
-        safecopy.CopyIn(dst, unsafe.Pointer(u))
-    } else {
-        // Type UContext64 doesn't have a packed layout in memory, fallback to MarshalBytes.
-        u.MarshalBytes(dst)
-    }
-}
-
-// UnmarshalUnsafe implements marshal.Marshallable.UnmarshalUnsafe.
-func (u *UContext64) UnmarshalUnsafe(src []byte) {
-    if u.MContext.Packed() && u.Sigset.Packed() && u.Stack.Packed() {
-        safecopy.CopyOut(unsafe.Pointer(u), src)
-    } else {
-        // Type UContext64 doesn't have a packed layout in memory, fallback to UnmarshalBytes.
-        u.UnmarshalBytes(src)
-    }
-}
-
-// CopyOutN implements marshal.Marshallable.CopyOutN.
-//go:nosplit
-func (u *UContext64) CopyOutN(cc marshal.CopyContext, addr usermem.Addr, limit int) (int, error) {
-    if !u.MContext.Packed() && u.Sigset.Packed() && u.Stack.Packed() {
-        // Type UContext64 doesn't have a packed layout in memory, fall back to MarshalBytes.
-        buf := cc.CopyScratchBuffer(u.SizeBytes()) // escapes: okay.
-        u.MarshalBytes(buf) // escapes: fallback.
-        return cc.CopyOutBytes(addr, buf[:limit]) // escapes: okay.
-    }
-
-    // Construct a slice backed by dst's underlying memory.
-    var buf []byte
-    hdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
-    hdr.Data = uintptr(gohacks.Noescape(unsafe.Pointer(u)))
-    hdr.Len = u.SizeBytes()
-    hdr.Cap = u.SizeBytes()
-
-    length, err := cc.CopyOutBytes(addr, buf[:limit]) // escapes: okay.
-    // Since we bypassed the compiler's escape analysis, indicate that u
-    // must live until the use above.
-    runtime.KeepAlive(u) // escapes: replaced by intrinsic.
-    return length, err
-}
-
-// CopyOut implements marshal.Marshallable.CopyOut.
-//go:nosplit
-func (u *UContext64) CopyOut(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
-    return u.CopyOutN(cc, addr, u.SizeBytes())
-}
-
-// CopyIn implements marshal.Marshallable.CopyIn.
-//go:nosplit
-func (u *UContext64) CopyIn(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
-    if !u.MContext.Packed() && u.Sigset.Packed() && u.Stack.Packed() {
-        // Type UContext64 doesn't have a packed layout in memory, fall back to UnmarshalBytes.
-        buf := cc.CopyScratchBuffer(u.SizeBytes()) // escapes: okay.
-        length, err := cc.CopyInBytes(addr, buf) // escapes: okay.
-        // Unmarshal unconditionally. If we had a short copy-in, this results in a
-        // partially unmarshalled struct.
-        u.UnmarshalBytes(buf) // escapes: fallback.
-        return length, err
-    }
-
-    // Construct a slice backed by dst's underlying memory.
-    var buf []byte
-    hdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
-    hdr.Data = uintptr(gohacks.Noescape(unsafe.Pointer(u)))
-    hdr.Len = u.SizeBytes()
-    hdr.Cap = u.SizeBytes()
-
-    length, err := cc.CopyInBytes(addr, buf) // escapes: okay.
-    // Since we bypassed the compiler's escape analysis, indicate that u
-    // must live until the use above.
-    runtime.KeepAlive(u) // escapes: replaced by intrinsic.
-    return length, err
-}
-
-// WriteTo implements io.WriterTo.WriteTo.
-func (u *UContext64) WriteTo(writer io.Writer) (int64, error) {
-    if !u.MContext.Packed() && u.Sigset.Packed() && u.Stack.Packed() {
-        // Type UContext64 doesn't have a packed layout in memory, fall back to MarshalBytes.
-        buf := make([]byte, u.SizeBytes())
-        u.MarshalBytes(buf)
-        length, err := writer.Write(buf)
-        return int64(length), err
-    }
-
-    // Construct a slice backed by dst's underlying memory.
-    var buf []byte
-    hdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
-    hdr.Data = uintptr(gohacks.Noescape(unsafe.Pointer(u)))
-    hdr.Len = u.SizeBytes()
-    hdr.Cap = u.SizeBytes()
-
-    length, err := writer.Write(buf)
-    // Since we bypassed the compiler's escape analysis, indicate that u
-    // must live until the use above.
-    runtime.KeepAlive(u) // escapes: replaced by intrinsic.
-    return int64(length), err
-}
-
diff --git a/pkg/sentry/kernel/auth/auth_abi_autogen_unsafe.go b/pkg/sentry/kernel/auth/auth_abi_autogen_unsafe.go
index d0c9ec652..da6aad4a5 100644
--- a/pkg/sentry/kernel/auth/auth_abi_autogen_unsafe.go
+++ b/pkg/sentry/kernel/auth/auth_abi_autogen_unsafe.go
@@ -19,6 +19,95 @@ var _ marshal.Marshallable = (*UID)(nil)
 
 // SizeBytes implements marshal.Marshallable.SizeBytes.
 //go:nosplit
+func (uid *UID) SizeBytes() int {
+    return 4
+}
+
+// MarshalBytes implements marshal.Marshallable.MarshalBytes.
+func (uid *UID) MarshalBytes(dst []byte) {
+    usermem.ByteOrder.PutUint32(dst[:4], uint32(*uid))
+}
+
+// UnmarshalBytes implements marshal.Marshallable.UnmarshalBytes.
+func (uid *UID) UnmarshalBytes(src []byte) {
+    *uid = UID(uint32(usermem.ByteOrder.Uint32(src[:4])))
+}
+
+// Packed implements marshal.Marshallable.Packed.
+//go:nosplit
+func (uid *UID) Packed() bool {
+    // Scalar newtypes are always packed.
+    return true
+}
+
+// MarshalUnsafe implements marshal.Marshallable.MarshalUnsafe.
+func (uid *UID) MarshalUnsafe(dst []byte) {
+    safecopy.CopyIn(dst, unsafe.Pointer(uid))
+}
+
+// UnmarshalUnsafe implements marshal.Marshallable.UnmarshalUnsafe.
+func (uid *UID) UnmarshalUnsafe(src []byte) {
+    safecopy.CopyOut(unsafe.Pointer(uid), src)
+}
+
+// CopyOutN implements marshal.Marshallable.CopyOutN.
+//go:nosplit
+func (uid *UID) CopyOutN(cc marshal.CopyContext, addr usermem.Addr, limit int) (int, error) {
+    // Construct a slice backed by dst's underlying memory.
+    var buf []byte
+    hdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
+    hdr.Data = uintptr(gohacks.Noescape(unsafe.Pointer(uid)))
+    hdr.Len = uid.SizeBytes()
+    hdr.Cap = uid.SizeBytes()
+
+    length, err := cc.CopyOutBytes(addr, buf[:limit]) // escapes: okay.
+    // Since we bypassed the compiler's escape analysis, indicate that uid
+    // must live until the use above.
+    runtime.KeepAlive(uid) // escapes: replaced by intrinsic.
+    return length, err
+}
+
+// CopyOut implements marshal.Marshallable.CopyOut.
+//go:nosplit
+func (uid *UID) CopyOut(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
+    return uid.CopyOutN(cc, addr, uid.SizeBytes())
+}
+
+// CopyIn implements marshal.Marshallable.CopyIn.
+//go:nosplit
+func (uid *UID) CopyIn(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
+    // Construct a slice backed by dst's underlying memory.
+    var buf []byte
+    hdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
+    hdr.Data = uintptr(gohacks.Noescape(unsafe.Pointer(uid)))
+    hdr.Len = uid.SizeBytes()
+    hdr.Cap = uid.SizeBytes()
+
+    length, err := cc.CopyInBytes(addr, buf) // escapes: okay.
+    // Since we bypassed the compiler's escape analysis, indicate that uid
+    // must live until the use above.
+    runtime.KeepAlive(uid) // escapes: replaced by intrinsic.
+    return length, err
+}
+
+// WriteTo implements io.WriterTo.WriteTo.
+func (uid *UID) WriteTo(w io.Writer) (int64, error) {
+    // Construct a slice backed by dst's underlying memory.
+    var buf []byte
+    hdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
+    hdr.Data = uintptr(gohacks.Noescape(unsafe.Pointer(uid)))
+    hdr.Len = uid.SizeBytes()
+    hdr.Cap = uid.SizeBytes()
+
+    length, err := w.Write(buf)
+    // Since we bypassed the compiler's escape analysis, indicate that uid
+    // must live until the use above.
+    runtime.KeepAlive(uid) // escapes: replaced by intrinsic.
+    return int64(length), err
+}
+
+// SizeBytes implements marshal.Marshallable.SizeBytes.
+//go:nosplit
 func (gid *GID) SizeBytes() int {
     return 4
 }
@@ -194,92 +283,3 @@ func UnmarshalUnsafeGIDSlice(dst []GID, src []byte) (int, error) {
     return length, err
 }
 
-// SizeBytes implements marshal.Marshallable.SizeBytes.
-//go:nosplit
-func (uid *UID) SizeBytes() int {
-    return 4
-}
-
-// MarshalBytes implements marshal.Marshallable.MarshalBytes.
-func (uid *UID) MarshalBytes(dst []byte) {
-    usermem.ByteOrder.PutUint32(dst[:4], uint32(*uid))
-}
-
-// UnmarshalBytes implements marshal.Marshallable.UnmarshalBytes.
-func (uid *UID) UnmarshalBytes(src []byte) {
-    *uid = UID(uint32(usermem.ByteOrder.Uint32(src[:4])))
-}
-
-// Packed implements marshal.Marshallable.Packed.
-//go:nosplit
-func (uid *UID) Packed() bool {
-    // Scalar newtypes are always packed.
-    return true
-}
-
-// MarshalUnsafe implements marshal.Marshallable.MarshalUnsafe.
-func (uid *UID) MarshalUnsafe(dst []byte) {
-    safecopy.CopyIn(dst, unsafe.Pointer(uid))
-}
-
-// UnmarshalUnsafe implements marshal.Marshallable.UnmarshalUnsafe.
-func (uid *UID) UnmarshalUnsafe(src []byte) {
-    safecopy.CopyOut(unsafe.Pointer(uid), src)
-}
-
-// CopyOutN implements marshal.Marshallable.CopyOutN.
-//go:nosplit
-func (uid *UID) CopyOutN(cc marshal.CopyContext, addr usermem.Addr, limit int) (int, error) {
-    // Construct a slice backed by dst's underlying memory.
-    var buf []byte
-    hdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
-    hdr.Data = uintptr(gohacks.Noescape(unsafe.Pointer(uid)))
-    hdr.Len = uid.SizeBytes()
-    hdr.Cap = uid.SizeBytes()
-
-    length, err := cc.CopyOutBytes(addr, buf[:limit]) // escapes: okay.
-    // Since we bypassed the compiler's escape analysis, indicate that uid
-    // must live until the use above.
-    runtime.KeepAlive(uid) // escapes: replaced by intrinsic.
-    return length, err
-}
-
-// CopyOut implements marshal.Marshallable.CopyOut.
-//go:nosplit
-func (uid *UID) CopyOut(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
-    return uid.CopyOutN(cc, addr, uid.SizeBytes())
-}
-
-// CopyIn implements marshal.Marshallable.CopyIn.
-//go:nosplit
-func (uid *UID) CopyIn(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
-    // Construct a slice backed by dst's underlying memory.
-    var buf []byte
-    hdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
-    hdr.Data = uintptr(gohacks.Noescape(unsafe.Pointer(uid)))
-    hdr.Len = uid.SizeBytes()
-    hdr.Cap = uid.SizeBytes()
-
-    length, err := cc.CopyInBytes(addr, buf) // escapes: okay.
-    // Since we bypassed the compiler's escape analysis, indicate that uid
-    // must live until the use above.
-    runtime.KeepAlive(uid) // escapes: replaced by intrinsic.
-    return length, err
-}
-
-// WriteTo implements io.WriterTo.WriteTo.
-func (uid *UID) WriteTo(w io.Writer) (int64, error) {
-    // Construct a slice backed by dst's underlying memory.
-    var buf []byte
-    hdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
-    hdr.Data = uintptr(gohacks.Noescape(unsafe.Pointer(uid)))
-    hdr.Len = uid.SizeBytes()
-    hdr.Cap = uid.SizeBytes()
-
-    length, err := w.Write(buf)
-    // Since we bypassed the compiler's escape analysis, indicate that uid
-    // must live until the use above.
-    runtime.KeepAlive(uid) // escapes: replaced by intrinsic.
-    return int64(length), err
-}
-
diff --git a/pkg/sentry/syscalls/linux/linux_abi_autogen_unsafe.go b/pkg/sentry/syscalls/linux/linux_abi_autogen_unsafe.go
index 956643160..862c286d9 100644
--- a/pkg/sentry/syscalls/linux/linux_abi_autogen_unsafe.go
+++ b/pkg/sentry/syscalls/linux/linux_abi_autogen_unsafe.go
@@ -23,156 +23,156 @@ var _ marshal.Marshallable = (*rlimit64)(nil)
 var _ marshal.Marshallable = (*userSockFprog)(nil)
 
 // SizeBytes implements marshal.Marshallable.SizeBytes.
-func (o *oldDirentHdr) SizeBytes() int {
-    return 18
+func (d *direntHdr) SizeBytes() int {
+    return 1 +
+        (*oldDirentHdr)(nil).SizeBytes()
 }
 
 // MarshalBytes implements marshal.Marshallable.MarshalBytes.
-func (o *oldDirentHdr) MarshalBytes(dst []byte) {
-    usermem.ByteOrder.PutUint64(dst[:8], uint64(o.Ino))
-    dst = dst[8:]
-    usermem.ByteOrder.PutUint64(dst[:8], uint64(o.Off))
-    dst = dst[8:]
-    usermem.ByteOrder.PutUint16(dst[:2], uint16(o.Reclen))
-    dst = dst[2:]
+func (d *direntHdr) MarshalBytes(dst []byte) {
+    d.OldHdr.MarshalBytes(dst[:d.OldHdr.SizeBytes()])
+    dst = dst[d.OldHdr.SizeBytes():]
+    dst[0] = byte(d.Typ)
+    dst = dst[1:]
 }
 
 // UnmarshalBytes implements marshal.Marshallable.UnmarshalBytes.
-func (o *oldDirentHdr) UnmarshalBytes(src []byte) {
-    o.Ino = uint64(usermem.ByteOrder.Uint64(src[:8]))
-    src = src[8:]
-    o.Off = uint64(usermem.ByteOrder.Uint64(src[:8]))
-    src = src[8:]
-    o.Reclen = uint16(usermem.ByteOrder.Uint16(src[:2]))
-    src = src[2:]
+func (d *direntHdr) UnmarshalBytes(src []byte) {
+    d.OldHdr.UnmarshalBytes(src[:d.OldHdr.SizeBytes()])
+    src = src[d.OldHdr.SizeBytes():]
+    d.Typ = uint8(src[0])
+    src = src[1:]
 }
 
 // Packed implements marshal.Marshallable.Packed.
 //go:nosplit
-func (o *oldDirentHdr) Packed() bool {
+func (d *direntHdr) Packed() bool {
     return false
 }
 
 // MarshalUnsafe implements marshal.Marshallable.MarshalUnsafe.
-func (o *oldDirentHdr) MarshalUnsafe(dst []byte) {
-    // Type oldDirentHdr doesn't have a packed layout in memory, fallback to MarshalBytes.
-    o.MarshalBytes(dst)
+func (d *direntHdr) MarshalUnsafe(dst []byte) {
+    // Type direntHdr doesn't have a packed layout in memory, fallback to MarshalBytes.
+    d.MarshalBytes(dst)
 }
 
 // UnmarshalUnsafe implements marshal.Marshallable.UnmarshalUnsafe.
-func (o *oldDirentHdr) UnmarshalUnsafe(src []byte) {
-    // Type oldDirentHdr doesn't have a packed layout in memory, fallback to UnmarshalBytes.
-    o.UnmarshalBytes(src)
+func (d *direntHdr) UnmarshalUnsafe(src []byte) {
+    // Type direntHdr doesn't have a packed layout in memory, fallback to UnmarshalBytes.
+    d.UnmarshalBytes(src)
 }
 
 // CopyOutN implements marshal.Marshallable.CopyOutN.
 //go:nosplit
-func (o *oldDirentHdr) CopyOutN(cc marshal.CopyContext, addr usermem.Addr, limit int) (int, error) {
-    // Type oldDirentHdr doesn't have a packed layout in memory, fall back to MarshalBytes.
-    buf := cc.CopyScratchBuffer(o.SizeBytes()) // escapes: okay.
-    o.MarshalBytes(buf) // escapes: fallback.
+func (d *direntHdr) CopyOutN(cc marshal.CopyContext, addr usermem.Addr, limit int) (int, error) {
+    // Type direntHdr doesn't have a packed layout in memory, fall back to MarshalBytes.
+    buf := cc.CopyScratchBuffer(d.SizeBytes()) // escapes: okay.
+    d.MarshalBytes(buf) // escapes: fallback.
     return cc.CopyOutBytes(addr, buf[:limit]) // escapes: okay.
 }
 
 // CopyOut implements marshal.Marshallable.CopyOut.
 //go:nosplit
-func (o *oldDirentHdr) CopyOut(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
-    return o.CopyOutN(cc, addr, o.SizeBytes())
+func (d *direntHdr) CopyOut(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
+    return d.CopyOutN(cc, addr, d.SizeBytes())
 }
 
 // CopyIn implements marshal.Marshallable.CopyIn.
 //go:nosplit
-func (o *oldDirentHdr) CopyIn(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
-    // Type oldDirentHdr doesn't have a packed layout in memory, fall back to UnmarshalBytes.
-    buf := cc.CopyScratchBuffer(o.SizeBytes()) // escapes: okay.
+func (d *direntHdr) CopyIn(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
+    // Type direntHdr doesn't have a packed layout in memory, fall back to UnmarshalBytes.
+    buf := cc.CopyScratchBuffer(d.SizeBytes()) // escapes: okay.
     length, err := cc.CopyInBytes(addr, buf) // escapes: okay.
     // Unmarshal unconditionally. If we had a short copy-in, this results in a
     // partially unmarshalled struct.
-    o.UnmarshalBytes(buf) // escapes: fallback.
+    d.UnmarshalBytes(buf) // escapes: fallback.
     return length, err
 }
 
 // WriteTo implements io.WriterTo.WriteTo.
-func (o *oldDirentHdr) WriteTo(writer io.Writer) (int64, error) {
-    // Type oldDirentHdr doesn't have a packed layout in memory, fall back to MarshalBytes.
-    buf := make([]byte, o.SizeBytes())
-    o.MarshalBytes(buf)
+func (d *direntHdr) WriteTo(writer io.Writer) (int64, error) {
+    // Type direntHdr doesn't have a packed layout in memory, fall back to MarshalBytes.
+    buf := make([]byte, d.SizeBytes())
+    d.MarshalBytes(buf)
     length, err := writer.Write(buf)
     return int64(length), err
 }
 
 // SizeBytes implements marshal.Marshallable.SizeBytes.
-func (d *direntHdr) SizeBytes() int {
-    return 1 +
-        (*oldDirentHdr)(nil).SizeBytes()
+func (o *oldDirentHdr) SizeBytes() int {
+    return 18
 }
 
 // MarshalBytes implements marshal.Marshallable.MarshalBytes.
-func (d *direntHdr) MarshalBytes(dst []byte) {
-    d.OldHdr.MarshalBytes(dst[:d.OldHdr.SizeBytes()])
-    dst = dst[d.OldHdr.SizeBytes():]
-    dst[0] = byte(d.Typ)
-    dst = dst[1:]
+func (o *oldDirentHdr) MarshalBytes(dst []byte) {
+    usermem.ByteOrder.PutUint64(dst[:8], uint64(o.Ino))
+    dst = dst[8:]
+    usermem.ByteOrder.PutUint64(dst[:8], uint64(o.Off))
+    dst = dst[8:]
+    usermem.ByteOrder.PutUint16(dst[:2], uint16(o.Reclen))
+    dst = dst[2:]
 }
 
 // UnmarshalBytes implements marshal.Marshallable.UnmarshalBytes.
-func (d *direntHdr) UnmarshalBytes(src []byte) {
-    d.OldHdr.UnmarshalBytes(src[:d.OldHdr.SizeBytes()])
-    src = src[d.OldHdr.SizeBytes():]
-    d.Typ = uint8(src[0])
-    src = src[1:]
+func (o *oldDirentHdr) UnmarshalBytes(src []byte) {
+    o.Ino = uint64(usermem.ByteOrder.Uint64(src[:8]))
+    src = src[8:]
+    o.Off = uint64(usermem.ByteOrder.Uint64(src[:8]))
+    src = src[8:]
+    o.Reclen = uint16(usermem.ByteOrder.Uint16(src[:2]))
+    src = src[2:]
 }
 
 // Packed implements marshal.Marshallable.Packed.
 //go:nosplit
-func (d *direntHdr) Packed() bool {
+func (o *oldDirentHdr) Packed() bool {
     return false
 }
 
 // MarshalUnsafe implements marshal.Marshallable.MarshalUnsafe.
-func (d *direntHdr) MarshalUnsafe(dst []byte) {
-    // Type direntHdr doesn't have a packed layout in memory, fallback to MarshalBytes.
-    d.MarshalBytes(dst)
+func (o *oldDirentHdr) MarshalUnsafe(dst []byte) {
+    // Type oldDirentHdr doesn't have a packed layout in memory, fallback to MarshalBytes.
+    o.MarshalBytes(dst)
 }
 
 // UnmarshalUnsafe implements marshal.Marshallable.UnmarshalUnsafe.
-func (d *direntHdr) UnmarshalUnsafe(src []byte) {
-    // Type direntHdr doesn't have a packed layout in memory, fallback to UnmarshalBytes.
-    d.UnmarshalBytes(src)
+func (o *oldDirentHdr) UnmarshalUnsafe(src []byte) {
+    // Type oldDirentHdr doesn't have a packed layout in memory, fallback to UnmarshalBytes.
+    o.UnmarshalBytes(src)
 }
 
 // CopyOutN implements marshal.Marshallable.CopyOutN.
 //go:nosplit
-func (d *direntHdr) CopyOutN(cc marshal.CopyContext, addr usermem.Addr, limit int) (int, error) {
-    // Type direntHdr doesn't have a packed layout in memory, fall back to MarshalBytes.
-    buf := cc.CopyScratchBuffer(d.SizeBytes()) // escapes: okay.
-    d.MarshalBytes(buf) // escapes: fallback.
+func (o *oldDirentHdr) CopyOutN(cc marshal.CopyContext, addr usermem.Addr, limit int) (int, error) {
+    // Type oldDirentHdr doesn't have a packed layout in memory, fall back to MarshalBytes.
+    buf := cc.CopyScratchBuffer(o.SizeBytes()) // escapes: okay.
+    o.MarshalBytes(buf) // escapes: fallback.
     return cc.CopyOutBytes(addr, buf[:limit]) // escapes: okay.
 }
 
 // CopyOut implements marshal.Marshallable.CopyOut.
 //go:nosplit
-func (d *direntHdr) CopyOut(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
-    return d.CopyOutN(cc, addr, d.SizeBytes())
+func (o *oldDirentHdr) CopyOut(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
+    return o.CopyOutN(cc, addr, o.SizeBytes())
 }
 
 // CopyIn implements marshal.Marshallable.CopyIn.
 //go:nosplit
-func (d *direntHdr) CopyIn(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
-    // Type direntHdr doesn't have a packed layout in memory, fall back to UnmarshalBytes.
-    buf := cc.CopyScratchBuffer(d.SizeBytes()) // escapes: okay.
+func (o *oldDirentHdr) CopyIn(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
+    // Type oldDirentHdr doesn't have a packed layout in memory, fall back to UnmarshalBytes.
+    buf := cc.CopyScratchBuffer(o.SizeBytes()) // escapes: okay.
     length, err := cc.CopyInBytes(addr, buf) // escapes: okay.
     // Unmarshal unconditionally. If we had a short copy-in, this results in a
     // partially unmarshalled struct.
-    d.UnmarshalBytes(buf) // escapes: fallback.
+    o.UnmarshalBytes(buf) // escapes: fallback.
     return length, err
 }
 
 // WriteTo implements io.WriterTo.WriteTo.
-func (d *direntHdr) WriteTo(writer io.Writer) (int64, error) {
-    // Type direntHdr doesn't have a packed layout in memory, fall back to MarshalBytes.
-    buf := make([]byte, d.SizeBytes())
-    d.MarshalBytes(buf)
+func (o *oldDirentHdr) WriteTo(writer io.Writer) (int64, error) {
+    // Type oldDirentHdr doesn't have a packed layout in memory, fall back to MarshalBytes.
+    buf := make([]byte, o.SizeBytes())
+    o.MarshalBytes(buf)
     length, err := writer.Write(buf)
     return int64(length), err
 }
diff --git a/pkg/sentry/syscalls/linux/vfs2/vfs2_abi_autogen_unsafe.go b/pkg/sentry/syscalls/linux/vfs2/vfs2_abi_autogen_unsafe.go
index 516ea1842..ccd56285a 100644
--- a/pkg/sentry/syscalls/linux/vfs2/vfs2_abi_autogen_unsafe.go
+++ b/pkg/sentry/syscalls/linux/vfs2/vfs2_abi_autogen_unsafe.go
@@ -112,26 +112,49 @@ func (s *sigSetWithSize) WriteTo(writer io.Writer) (int64, error) {
 }
 
 // SizeBytes implements marshal.Marshallable.SizeBytes.
-func (m *multipleMessageHeader64) SizeBytes() int {
-    return 8 +
-        (*MessageHeader64)(nil).SizeBytes()
+func (m *MessageHeader64) SizeBytes() int {
+    return 56
 }
 
 // MarshalBytes implements marshal.Marshallable.MarshalBytes.
-func (m *multipleMessageHeader64) MarshalBytes(dst []byte) {
-    m.msgHdr.MarshalBytes(dst[:m.msgHdr.SizeBytes()])
-    dst = dst[m.msgHdr.SizeBytes():]
-    usermem.ByteOrder.PutUint32(dst[:4], uint32(m.msgLen))
+func (m *MessageHeader64) MarshalBytes(dst []byte) {
+    usermem.ByteOrder.PutUint64(dst[:8], uint64(m.Name))
+    dst = dst[8:]
+    usermem.ByteOrder.PutUint32(dst[:4], uint32(m.NameLen))
+    dst = dst[4:]
+    // Padding: dst[:sizeof(uint32)] ~= uint32(0)
+    dst = dst[4:]
+    usermem.ByteOrder.PutUint64(dst[:8], uint64(m.Iov))
+    dst = dst[8:]
+    usermem.ByteOrder.PutUint64(dst[:8], uint64(m.IovLen))
+    dst = dst[8:]
+    usermem.ByteOrder.PutUint64(dst[:8], uint64(m.Control))
+    dst = dst[8:]
+    usermem.ByteOrder.PutUint64(dst[:8], uint64(m.ControlLen))
+    dst = dst[8:]
+    usermem.ByteOrder.PutUint32(dst[:4], uint32(m.Flags))
     dst = dst[4:]
     // Padding: dst[:sizeof(int32)] ~= int32(0)
     dst = dst[4:]
 }
 
 // UnmarshalBytes implements marshal.Marshallable.UnmarshalBytes.
-func (m *multipleMessageHeader64) UnmarshalBytes(src []byte) {
-    m.msgHdr.UnmarshalBytes(src[:m.msgHdr.SizeBytes()])
-    src = src[m.msgHdr.SizeBytes():]
-    m.msgLen = uint32(usermem.ByteOrder.Uint32(src[:4]))
+func (m *MessageHeader64) UnmarshalBytes(src []byte) {
+    m.Name = uint64(usermem.ByteOrder.Uint64(src[:8]))
+    src = src[8:]
+    m.NameLen = uint32(usermem.ByteOrder.Uint32(src[:4]))
+    src = src[4:]
+    // Padding: var _ uint32 ~= src[:sizeof(uint32)]
+    src = src[4:]
+    m.Iov = uint64(usermem.ByteOrder.Uint64(src[:8]))
+    src = src[8:]
+    m.IovLen = uint64(usermem.ByteOrder.Uint64(src[:8]))
+    src = src[8:]
+    m.Control = uint64(usermem.ByteOrder.Uint64(src[:8]))
+    src = src[8:]
+    m.ControlLen = uint64(usermem.ByteOrder.Uint64(src[:8]))
+    src = src[8:]
+    m.Flags = int32(usermem.ByteOrder.Uint32(src[:4]))
     src = src[4:]
     // Padding: var _ int32 ~= src[:sizeof(int32)]
     src = src[4:]
@@ -139,40 +162,23 @@ func (m *multipleMessageHeader64) UnmarshalBytes(src []byte) {
 
 // Packed implements marshal.Marshallable.Packed.
 //go:nosplit
-func (m *multipleMessageHeader64) Packed() bool {
-    return m.msgHdr.Packed()
+func (m *MessageHeader64) Packed() bool {
+    return true
 }
 
 // MarshalUnsafe implements marshal.Marshallable.MarshalUnsafe.
-func (m *multipleMessageHeader64) MarshalUnsafe(dst []byte) {
-    if m.msgHdr.Packed() {
-        safecopy.CopyIn(dst, unsafe.Pointer(m))
-    } else {
-        // Type multipleMessageHeader64 doesn't have a packed layout in memory, fallback to MarshalBytes.
-        m.MarshalBytes(dst)
-    }
+func (m *MessageHeader64) MarshalUnsafe(dst []byte) {
+    safecopy.CopyIn(dst, unsafe.Pointer(m))
 }
 
 // UnmarshalUnsafe implements marshal.Marshallable.UnmarshalUnsafe.
-func (m *multipleMessageHeader64) UnmarshalUnsafe(src []byte) {
-    if m.msgHdr.Packed() {
-        safecopy.CopyOut(unsafe.Pointer(m), src)
-    } else {
-        // Type multipleMessageHeader64 doesn't have a packed layout in memory, fallback to UnmarshalBytes.
-        m.UnmarshalBytes(src)
-    }
+func (m *MessageHeader64) UnmarshalUnsafe(src []byte) {
+    safecopy.CopyOut(unsafe.Pointer(m), src)
 }
 
 // CopyOutN implements marshal.Marshallable.CopyOutN.
 //go:nosplit
-func (m *multipleMessageHeader64) CopyOutN(cc marshal.CopyContext, addr usermem.Addr, limit int) (int, error) {
-    if !m.msgHdr.Packed() {
-        // Type multipleMessageHeader64 doesn't have a packed layout in memory, fall back to MarshalBytes.
-        buf := cc.CopyScratchBuffer(m.SizeBytes()) // escapes: okay.
-        m.MarshalBytes(buf) // escapes: fallback.
-        return cc.CopyOutBytes(addr, buf[:limit]) // escapes: okay.
-    }
-
+func (m *MessageHeader64) CopyOutN(cc marshal.CopyContext, addr usermem.Addr, limit int) (int, error) {
     // Construct a slice backed by dst's underlying memory.
     var buf []byte
     hdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
@@ -189,23 +195,13 @@ func (m *multipleMessageHeader64) CopyOutN(cc marshal.CopyContext, addr usermem.
 
 // CopyOut implements marshal.Marshallable.CopyOut.
 //go:nosplit
-func (m *multipleMessageHeader64) CopyOut(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
+func (m *MessageHeader64) CopyOut(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
     return m.CopyOutN(cc, addr, m.SizeBytes())
 }
 
 // CopyIn implements marshal.Marshallable.CopyIn.
 //go:nosplit
-func (m *multipleMessageHeader64) CopyIn(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
-    if !m.msgHdr.Packed() {
-        // Type multipleMessageHeader64 doesn't have a packed layout in memory, fall back to UnmarshalBytes.
-        buf := cc.CopyScratchBuffer(m.SizeBytes()) // escapes: okay.
-        length, err := cc.CopyInBytes(addr, buf) // escapes: okay.
-        // Unmarshal unconditionally. If we had a short copy-in, this results in a
-        // partially unmarshalled struct.
-        m.UnmarshalBytes(buf) // escapes: fallback.
-        return length, err
-    }
-
+func (m *MessageHeader64) CopyIn(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
     // Construct a slice backed by dst's underlying memory.
     var buf []byte
     hdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
@@ -221,15 +217,7 @@ func (m *multipleMessageHeader64) CopyIn(cc marshal.CopyContext, addr usermem.Ad
 }
 
 // WriteTo implements io.WriterTo.WriteTo.
-func (m *multipleMessageHeader64) WriteTo(writer io.Writer) (int64, error) {
-    if !m.msgHdr.Packed() {
-        // Type multipleMessageHeader64 doesn't have a packed layout in memory, fall back to MarshalBytes.
-        buf := make([]byte, m.SizeBytes())
-        m.MarshalBytes(buf)
-        length, err := writer.Write(buf)
-        return int64(length), err
-    }
-
+func (m *MessageHeader64) WriteTo(writer io.Writer) (int64, error) {
     // Construct a slice backed by dst's underlying memory.
     var buf []byte
     hdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
@@ -245,49 +233,26 @@ func (m *multipleMessageHeader64) WriteTo(writer io.Writer) (int64, error) {
 }
 
 // SizeBytes implements marshal.Marshallable.SizeBytes.
-func (m *MessageHeader64) SizeBytes() int {
-    return 56
+func (m *multipleMessageHeader64) SizeBytes() int {
+    return 8 +
+        (*MessageHeader64)(nil).SizeBytes()
 }
 
 // MarshalBytes implements marshal.Marshallable.MarshalBytes.
-func (m *MessageHeader64) MarshalBytes(dst []byte) {
-    usermem.ByteOrder.PutUint64(dst[:8], uint64(m.Name))
-    dst = dst[8:]
-    usermem.ByteOrder.PutUint32(dst[:4], uint32(m.NameLen))
-    dst = dst[4:]
-    // Padding: dst[:sizeof(uint32)] ~= uint32(0)
-    dst = dst[4:]
-    usermem.ByteOrder.PutUint64(dst[:8], uint64(m.Iov))
-    dst = dst[8:]
-    usermem.ByteOrder.PutUint64(dst[:8], uint64(m.IovLen))
-    dst = dst[8:]
-    usermem.ByteOrder.PutUint64(dst[:8], uint64(m.Control))
-    dst = dst[8:]
-    usermem.ByteOrder.PutUint64(dst[:8], uint64(m.ControlLen))
-    dst = dst[8:]
-    usermem.ByteOrder.PutUint32(dst[:4], uint32(m.Flags))
+func (m *multipleMessageHeader64) MarshalBytes(dst []byte) {
+    m.msgHdr.MarshalBytes(dst[:m.msgHdr.SizeBytes()])
+    dst = dst[m.msgHdr.SizeBytes():]
+    usermem.ByteOrder.PutUint32(dst[:4], uint32(m.msgLen))
     dst = dst[4:]
     // Padding: dst[:sizeof(int32)] ~= int32(0)
     dst = dst[4:]
 }
 
 // UnmarshalBytes implements marshal.Marshallable.UnmarshalBytes.
-func (m *MessageHeader64) UnmarshalBytes(src []byte) {
-    m.Name = uint64(usermem.ByteOrder.Uint64(src[:8]))
-    src = src[8:]
-    m.NameLen = uint32(usermem.ByteOrder.Uint32(src[:4]))
-    src = src[4:]
-    // Padding: var _ uint32 ~= src[:sizeof(uint32)]
-    src = src[4:]
-    m.Iov = uint64(usermem.ByteOrder.Uint64(src[:8]))
-    src = src[8:]
-    m.IovLen = uint64(usermem.ByteOrder.Uint64(src[:8]))
-    src = src[8:]
-    m.Control = uint64(usermem.ByteOrder.Uint64(src[:8]))
-    src = src[8:]
-    m.ControlLen = uint64(usermem.ByteOrder.Uint64(src[:8]))
-    src = src[8:]
-    m.Flags = int32(usermem.ByteOrder.Uint32(src[:4]))
+func (m *multipleMessageHeader64) UnmarshalBytes(src []byte) {
+    m.msgHdr.UnmarshalBytes(src[:m.msgHdr.SizeBytes()])
+    src = src[m.msgHdr.SizeBytes():]
+    m.msgLen = uint32(usermem.ByteOrder.Uint32(src[:4]))
     src = src[4:]
     // Padding: var _ int32 ~= src[:sizeof(int32)]
     src = src[4:]
@@ -295,23 +260,40 @@ func (m *MessageHeader64) UnmarshalBytes(src []byte) {
 
 // Packed implements marshal.Marshallable.Packed.
 //go:nosplit
-func (m *MessageHeader64) Packed() bool {
-    return true
+func (m *multipleMessageHeader64) Packed() bool {
+    return m.msgHdr.Packed()
 }
 
 // MarshalUnsafe implements marshal.Marshallable.MarshalUnsafe.
-func (m *MessageHeader64) MarshalUnsafe(dst []byte) {
-    safecopy.CopyIn(dst, unsafe.Pointer(m))
+func (m *multipleMessageHeader64) MarshalUnsafe(dst []byte) {
+    if m.msgHdr.Packed() {
+        safecopy.CopyIn(dst, unsafe.Pointer(m))
+    } else {
+        // Type multipleMessageHeader64 doesn't have a packed layout in memory, fallback to MarshalBytes.
+        m.MarshalBytes(dst)
+    }
 }
 
 // UnmarshalUnsafe implements marshal.Marshallable.UnmarshalUnsafe.
-func (m *MessageHeader64) UnmarshalUnsafe(src []byte) {
-    safecopy.CopyOut(unsafe.Pointer(m), src)
+func (m *multipleMessageHeader64) UnmarshalUnsafe(src []byte) {
+    if m.msgHdr.Packed() {
+        safecopy.CopyOut(unsafe.Pointer(m), src)
+    } else {
+        // Type multipleMessageHeader64 doesn't have a packed layout in memory, fallback to UnmarshalBytes.
+        m.UnmarshalBytes(src)
+    }
 }
 
 // CopyOutN implements marshal.Marshallable.CopyOutN.
 //go:nosplit
-func (m *MessageHeader64) CopyOutN(cc marshal.CopyContext, addr usermem.Addr, limit int) (int, error) {
+func (m *multipleMessageHeader64) CopyOutN(cc marshal.CopyContext, addr usermem.Addr, limit int) (int, error) {
+    if !m.msgHdr.Packed() {
+        // Type multipleMessageHeader64 doesn't have a packed layout in memory, fall back to MarshalBytes.
+        buf := cc.CopyScratchBuffer(m.SizeBytes()) // escapes: okay.
+        m.MarshalBytes(buf) // escapes: fallback.
+        return cc.CopyOutBytes(addr, buf[:limit]) // escapes: okay.
+    }
+
     // Construct a slice backed by dst's underlying memory.
     var buf []byte
     hdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
@@ -328,13 +310,23 @@ func (m *MessageHeader64) CopyOutN(cc marshal.CopyContext, addr usermem.Addr, li
 
 // CopyOut implements marshal.Marshallable.CopyOut.
 //go:nosplit
-func (m *MessageHeader64) CopyOut(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
+func (m *multipleMessageHeader64) CopyOut(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
     return m.CopyOutN(cc, addr, m.SizeBytes())
 }
 
 // CopyIn implements marshal.Marshallable.CopyIn.
 //go:nosplit
-func (m *MessageHeader64) CopyIn(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
+func (m *multipleMessageHeader64) CopyIn(cc marshal.CopyContext, addr usermem.Addr) (int, error) {
+    if !m.msgHdr.Packed() {
+        // Type multipleMessageHeader64 doesn't have a packed layout in memory, fall back to UnmarshalBytes.
+        buf := cc.CopyScratchBuffer(m.SizeBytes()) // escapes: okay.
+        length, err := cc.CopyInBytes(addr, buf) // escapes: okay.
+        // Unmarshal unconditionally. If we had a short copy-in, this results in a
+        // partially unmarshalled struct.
+        m.UnmarshalBytes(buf) // escapes: fallback.
+        return length, err
+    }
+
     // Construct a slice backed by dst's underlying memory.
     var buf []byte
     hdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))
@@ -350,7 +342,15 @@ func (m *MessageHeader64) CopyIn(cc marshal.CopyContext, addr usermem.Addr) (int
 }
 
 // WriteTo implements io.WriterTo.WriteTo.
-func (m *MessageHeader64) WriteTo(writer io.Writer) (int64, error) {
+func (m *multipleMessageHeader64) WriteTo(writer io.Writer) (int64, error) {
+    if !m.msgHdr.Packed() {
+        // Type multipleMessageHeader64 doesn't have a packed layout in memory, fall back to MarshalBytes.
+        buf := make([]byte, m.SizeBytes())
+        m.MarshalBytes(buf)
+        length, err := writer.Write(buf)
+        return int64(length), err
+    }
+
     // Construct a slice backed by dst's underlying memory.
     var buf []byte
     hdr := (*reflect.SliceHeader)(unsafe.Pointer(&buf))