Merge changes I93edfd61,Icd23b542,I58c84607,Icfa73a75

* changes:
  Pass -fno-sanitize=vptr,function for musl
  Use musl rust prebuilts for USE_HOST_MUSL=true
  Don't package host cross modules in javaFuzzPackager
  Add rust musl arm and arm64 toolchains
diff --git a/android/arch.go b/android/arch.go
index 382a7df..e72614c 100644
--- a/android/arch.go
+++ b/android/arch.go
@@ -1825,7 +1825,9 @@
 	for _, t := range targets {
 		if _, found := set[t.Os.String()]; !found {
 			set[t.Os.String()] = true
-			ret = append(ret, commonTargetMap[t.Os.String()])
+			common := commonTargetMap[t.Os.String()]
+			common.HostCross = t.HostCross
+			ret = append(ret, common)
 		}
 	}
 
diff --git a/cc/sanitize.go b/cc/sanitize.go
index 8e0813d..86472a2 100644
--- a/cc/sanitize.go
+++ b/cc/sanitize.go
@@ -710,8 +710,13 @@
 			// Host sanitizers only link symbols in the final executable, so
 			// there will always be undefined symbols in intermediate libraries.
 			_, flags.Global.LdFlags = removeFromList("-Wl,--no-undefined", flags.Global.LdFlags)
+		}
 
-			// non-Bionic toolchain prebuilts are missing UBSan's vptr and function san
+		if !ctx.toolchain().Bionic() {
+			// non-Bionic toolchain prebuilts are missing UBSan's vptr and function san.
+			// Musl toolchain prebuilts have vptr and function sanitizers, but enabling them
+			// implicitly enables RTTI which causes RTTI mismatch issues with dependencies.
+
 			flags.Local.CFlags = append(flags.Local.CFlags, "-fno-sanitize=vptr,function")
 		}
 
diff --git a/java/fuzz.go b/java/fuzz.go
index b306991..d0f369f 100644
--- a/java/fuzz.go
+++ b/java/fuzz.go
@@ -171,6 +171,10 @@
 			return
 		}
 
+		if javaFuzzModule.Target().HostCross {
+			return
+		}
+
 		fuzzModuleValidator := fuzz.FuzzModule{
 			javaFuzzModule.ModuleBase,
 			javaFuzzModule.DefaultableModuleBase,
diff --git a/rust/bindgen.go b/rust/bindgen.go
index b4626a0..4d723d6 100644
--- a/rust/bindgen.go
+++ b/rust/bindgen.go
@@ -41,10 +41,25 @@
 
 	//TODO(b/160803703) Use a prebuilt bindgen instead of the built bindgen.
 	_ = pctx.HostBinToolVariable("bindgenCmd", "bindgen")
+	_ = pctx.VariableFunc("bindgenHostPrebuiltTag", func(ctx android.PackageVarContext) string {
+		if ctx.Config().UseHostMusl() {
+			// This is a hack to use the glibc bindgen binary until we have a musl version checked in.
+			return "linux-x86"
+		} else {
+			return "${config.HostPrebuiltTag}"
+		}
+	})
+	_ = pctx.VariableFunc("bindgenClangLibdir", func(ctx android.PackageVarContext) string {
+		if ctx.Config().UseHostMusl() {
+			return "musl/lib64/"
+		} else {
+			return "lib64/"
+		}
+	})
 	_ = pctx.SourcePathVariable("bindgenClang",
-		"${cc_config.ClangBase}/${config.HostPrebuiltTag}/${bindgenClangVersion}/bin/clang")
+		"${cc_config.ClangBase}/${bindgenHostPrebuiltTag}/${bindgenClangVersion}/bin/clang")
 	_ = pctx.SourcePathVariable("bindgenLibClang",
-		"${cc_config.ClangBase}/${config.HostPrebuiltTag}/${bindgenClangVersion}/lib64/")
+		"${cc_config.ClangBase}/${bindgenHostPrebuiltTag}/${bindgenClangVersion}/${bindgenClangLibdir}")
 
 	//TODO(ivanlozano) Switch this to RuleBuilder
 	bindgen = pctx.AndroidStaticRule("bindgen",
diff --git a/rust/compiler.go b/rust/compiler.go
index bcd58c8..365f1e0 100644
--- a/rust/compiler.go
+++ b/rust/compiler.go
@@ -372,7 +372,7 @@
 	if !Bool(compiler.Properties.No_stdlibs) {
 		for _, stdlib := range config.Stdlibs {
 			// If we're building for the build host, use the prebuilt stdlibs
-			if ctx.Target().Os == android.Linux || ctx.Target().Os == android.Darwin {
+			if ctx.Host() && !ctx.Target().HostCross {
 				stdlib = "prebuilt_" + stdlib
 			}
 			deps.Stdlibs = append(deps.Stdlibs, stdlib)
diff --git a/rust/config/Android.bp b/rust/config/Android.bp
index 7757c79..ba40cb0 100644
--- a/rust/config/Android.bp
+++ b/rust/config/Android.bp
@@ -11,6 +11,7 @@
     ],
     srcs: [
         "arm_device.go",
+        "arm_linux_host.go",
         "arm64_device.go",
         "global.go",
         "lints.go",
diff --git a/rust/config/arm_linux_host.go b/rust/config/arm_linux_host.go
new file mode 100644
index 0000000..22bdaee
--- /dev/null
+++ b/rust/config/arm_linux_host.go
@@ -0,0 +1,147 @@
+// Copyright 2022 Google Inc. All rights reserved.
+//
+// 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 config
+
+import (
+	"strings"
+
+	"android/soong/android"
+)
+
+var (
+	linuxArmRustflags   = []string{}
+	linuxArmLinkflags   = []string{}
+	linuxArm64Rustflags = []string{}
+	linuxArm64Linkflags = []string{}
+)
+
+func init() {
+	registerToolchainFactory(android.LinuxMusl, android.Arm64, linuxMuslArm64ToolchainFactory)
+	registerToolchainFactory(android.LinuxMusl, android.Arm, linuxMuslArmToolchainFactory)
+
+	pctx.StaticVariable("LinuxToolchainArmRustFlags", strings.Join(linuxArmRustflags, " "))
+	pctx.StaticVariable("LinuxToolchainArmLinkFlags", strings.Join(linuxArmLinkflags, " "))
+	pctx.StaticVariable("LinuxToolchainArm64RustFlags", strings.Join(linuxArm64Rustflags, " "))
+	pctx.StaticVariable("LinuxToolchainArm64LinkFlags", strings.Join(linuxArm64Linkflags, " "))
+}
+
+// Base 64-bit linux rust toolchain
+type toolchainLinuxArm64 struct {
+	toolchain64Bit
+}
+
+func (toolchainLinuxArm64) Supported() bool {
+	return true
+}
+
+func (toolchainLinuxArm64) Bionic() bool {
+	return false
+}
+
+func (t *toolchainLinuxArm64) Name() string {
+	return "arm64"
+}
+
+func (t *toolchainLinuxArm64) ToolchainLinkFlags() string {
+	// Prepend the lld flags from cc_config so we stay in sync with cc
+	return "${cc_config.LinuxLldflags} ${cc_config.LinuxArm64Lldflags} " +
+		"${config.LinuxToolchainLinkFlags} ${config.LinuxToolchainArm64LinkFlags}"
+}
+
+func (t *toolchainLinuxArm64) ToolchainRustFlags() string {
+	return "${config.LinuxToolchainRustFlags} ${config.LinuxToolchainArm64RustFlags}"
+}
+
+// Specialization of the 64-bit linux rust toolchain for musl.  Adds the musl rust triple and
+// linker flags to avoid using the host sysroot.
+type toolchainLinuxMuslArm64 struct {
+	toolchainLinuxArm64
+}
+
+func (t *toolchainLinuxMuslArm64) RustTriple() string {
+	return "aarch64-unknown-linux-musl"
+}
+
+func (t *toolchainLinuxMuslArm64) ToolchainLinkFlags() string {
+	return t.toolchainLinuxArm64.ToolchainLinkFlags() + " " + "${config.LinuxMuslToolchainLinkFlags}"
+}
+
+func (t *toolchainLinuxMuslArm64) ToolchainRustFlags() string {
+	return t.toolchainLinuxArm64.ToolchainRustFlags() + " " + "${config.LinuxMuslToolchainRustFlags}"
+}
+
+func linuxMuslArm64ToolchainFactory(arch android.Arch) Toolchain {
+	return toolchainLinuxMuslArm64Singleton
+}
+
+// Base 32-bit linux rust toolchain
+type toolchainLinuxArm struct {
+	toolchain32Bit
+}
+
+func (toolchainLinuxArm) Supported() bool {
+	return true
+}
+
+func (toolchainLinuxArm) Bionic() bool {
+	return false
+}
+
+func (t *toolchainLinuxArm) Name() string {
+	return "arm"
+}
+
+func (toolchainLinuxArm) LibclangRuntimeLibraryArch() string {
+	return "arm"
+}
+
+func (toolchainLinuxArm64) LibclangRuntimeLibraryArch() string {
+	return "arm64"
+}
+
+func (t *toolchainLinuxArm) ToolchainLinkFlags() string {
+	// Prepend the lld flags from cc_config so we stay in sync with cc
+	return "${cc_config.LinuxLldflags} ${cc_config.LinuxArmLldflags} " +
+		"${config.LinuxToolchainLinkFlags} ${config.LinuxToolchainArmLinkFlags}"
+}
+
+func (t *toolchainLinuxArm) ToolchainRustFlags() string {
+	return "${config.LinuxToolchainRustFlags} ${config.LinuxToolchainArmRustFlags}"
+}
+
+// Specialization of the 32-bit linux rust toolchain for musl.  Adds the musl rust triple and
+// linker flags to avoid using the host sysroot.
+type toolchainLinuxMuslArm struct {
+	toolchainLinuxArm
+}
+
+func (t *toolchainLinuxMuslArm) RustTriple() string {
+	return "arm-unknown-linux-musleabihf"
+}
+
+func (t *toolchainLinuxMuslArm) ToolchainLinkFlags() string {
+	return t.toolchainLinuxArm.ToolchainLinkFlags() + " " + "${config.LinuxMuslToolchainLinkFlags}"
+}
+
+func (t *toolchainLinuxMuslArm) ToolchainRustFlags() string {
+	return t.toolchainLinuxArm.ToolchainRustFlags() + " " + "${config.LinuxMuslToolchainRustFlags}"
+}
+
+func linuxMuslArmToolchainFactory(arch android.Arch) Toolchain {
+	return toolchainLinuxMuslArmSingleton
+}
+
+var toolchainLinuxMuslArm64Singleton Toolchain = &toolchainLinuxMuslArm64{}
+var toolchainLinuxMuslArmSingleton Toolchain = &toolchainLinuxMuslArm{}
diff --git a/rust/config/global.go b/rust/config/global.go
index e9751fd..3ef0ecb 100644
--- a/rust/config/global.go
+++ b/rust/config/global.go
@@ -78,7 +78,13 @@
 
 func init() {
 	pctx.SourcePathVariable("RustDefaultBase", RustDefaultBase)
-	pctx.VariableConfigMethod("HostPrebuiltTag", android.Config.PrebuiltOS)
+	pctx.VariableConfigMethod("HostPrebuiltTag", func(config android.Config) string {
+		if config.UseHostMusl() {
+			return "linux-musl-x86"
+		} else {
+			return config.PrebuiltOS()
+		}
+	})
 
 	pctx.VariableFunc("RustBase", func(ctx android.PackageVarContext) string {
 		if override := ctx.Config().Getenv("RUST_PREBUILTS_BASE"); override != "" {
diff --git a/rust/sanitize.go b/rust/sanitize.go
index 536fcbd..a3c5cb5 100644
--- a/rust/sanitize.go
+++ b/rust/sanitize.go
@@ -174,7 +174,7 @@
 	}
 
 	// Enable Memtag for all components in the include paths (for Aarch64 only)
-	if ctx.Arch().ArchType == android.Arm64 {
+	if ctx.Arch().ArchType == android.Arm64 && ctx.Os().Bionic() {
 		if ctx.Config().MemtagHeapSyncEnabledForPath(ctx.ModuleDir()) {
 			if s.Memtag_heap == nil {
 				s.Memtag_heap = proptools.BoolPtr(true)
@@ -200,7 +200,7 @@
 	}
 
 	// HWASan requires AArch64 hardware feature (top-byte-ignore).
-	if ctx.Arch().ArchType != android.Arm64 {
+	if ctx.Arch().ArchType != android.Arm64 || !ctx.Os().Bionic() {
 		s.Hwaddress = nil
 	}
 
@@ -215,7 +215,7 @@
 	}
 
 	// Memtag_heap is only implemented on AArch64.
-	if ctx.Arch().ArchType != android.Arm64 {
+	if ctx.Arch().ArchType != android.Arm64 || !ctx.Os().Bionic() {
 		s.Memtag_heap = nil
 	}
 
@@ -234,7 +234,7 @@
 	}
 	if Bool(sanitize.Properties.Sanitize.Fuzzer) {
 		flags.RustFlags = append(flags.RustFlags, fuzzerFlags...)
-		if ctx.Arch().ArchType == android.Arm64 {
+		if ctx.Arch().ArchType == android.Arm64 && ctx.Os().Bionic() {
 			flags.RustFlags = append(flags.RustFlags, hwasanFlags...)
 		} else {
 			flags.RustFlags = append(flags.RustFlags, asanFlags...)
@@ -282,13 +282,13 @@
 		var deps []string
 
 		if mod.IsSanitizerEnabled(cc.Asan) ||
-			(mod.IsSanitizerEnabled(cc.Fuzzer) && mctx.Arch().ArchType != android.Arm64) {
+			(mod.IsSanitizerEnabled(cc.Fuzzer) && (mctx.Arch().ArchType != android.Arm64 || !mctx.Os().Bionic())) {
 			variations = append(variations,
 				blueprint.Variation{Mutator: "link", Variation: "shared"})
 			depTag = cc.SharedDepTag()
 			deps = []string{config.LibclangRuntimeLibrary(mod.toolchain(mctx), "asan")}
 		} else if mod.IsSanitizerEnabled(cc.Hwasan) ||
-			(mod.IsSanitizerEnabled(cc.Fuzzer) && mctx.Arch().ArchType == android.Arm64) {
+			(mod.IsSanitizerEnabled(cc.Fuzzer) && mctx.Arch().ArchType == android.Arm64 && mctx.Os().Bionic()) {
 			// TODO(b/204776996): HWASan for static Rust binaries isn't supported yet.
 			if binary, ok := mod.compiler.(binaryInterface); ok {
 				if binary.staticallyLinked() {