Add some hostarch.Addr methods.

PiperOrigin-RevId: 582093671

pkg/hostarch/BUILD

@@ -34,6 +34,7 @@ go_library(
         "addr.go",
         "addr_range.go",
         "addr_range_seq_unsafe.go",
+        "addr_unsafe.go",
         "hostarch.go",
         "hostarch_arm64.go",
         "hostarch_x86.go",

pkg/hostarch/addr.go

@@ -33,9 +33,10 @@ type Addr uintptr
 // expected to ever come up in practice.
 func (v Addr) AddLength(length uint64) (end Addr, ok bool) {
 	end = v + Addr(length)
-	// The second half of the following check is needed in case uintptr is
-	// smaller than 64 bits.
-	ok = end >= v && length <= uint64(^Addr(0))
+	// As of this writing (Go 1.21), addrAtLeast64b is required to prevent the
+	// compiler from generating a tautological `length <= MaxUint64` check on
+	// 64-bit architectures.
+	ok = end >= v && (addrAtLeast64b || length <= uint64(^Addr(0)))
 	return
 }
 
@@ -64,6 +65,11 @@ func (v Addr) HugeRoundUp() (Addr, bool) {
 	return HugePageRoundUp(v)
 }
 
+// MustHugeRoundUp is equivalent to function MustHugePageRoundUp.
+func (v Addr) MustHugeRoundUp() Addr {
+	return MustHugePageRoundUp(v)
+}
+
 // PageOffset is equivalent to function PageOffset, except that it casts the
 // result to uint64.
 func (v Addr) PageOffset() uint64 {
@@ -75,6 +81,16 @@ func (v Addr) IsPageAligned() bool {
 	return IsPageAligned(v)
 }
 
+// HugePageOffset is equivalent to function HugePageOffset.
+func (v Addr) HugePageOffset() uint64 {
+	return uint64(HugePageOffset(v))
+}
+
+// IsHugePageAligned is equivalent to function IsHugePageAligned.
+func (v Addr) IsHugePageAligned() bool {
+	return IsHugePageAligned(v)
+}
+
 // AddrRange is a range of Addrs.
 //
 // type AddrRange <generated by go_generics>
@@ -91,6 +107,12 @@ func (ar AddrRange) IsPageAligned() bool {
 	return ar.Start.IsPageAligned() && ar.End.IsPageAligned()
 }
 
+// IsHugePageAligned returns true if ar.Start.IsHugePageAligned() and
+// ar.End.IsHugePageAligned().
+func (ar AddrRange) IsHugePageAligned() bool {
+	return ar.Start.IsHugePageAligned() && ar.End.IsHugePageAligned()
+}
+
 // String implements fmt.Stringer.String.
 func (ar AddrRange) String() string {
 	return fmt.Sprintf("[%#x, %#x)", ar.Start, ar.End)

pkg/hostarch/addr_unsafe.go

@@ -0,0 +1,22 @@
+// Copyright 2023 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 hostarch
+
+import (
+	"unsafe"
+)
+
+// This is used in addr.go:Addr.AddLength().
+const addrAtLeast64b = unsafe.Sizeof(Addr(0)) >= 8