Makefile: fix Android builds

There are 2 known problems with current Android support:
1. It does not work with newer NDK
(happens on every NDK update).
2. Dynamic Go binaries do not start on Android emulator.

Drop special Android support and just build static linux binaries.

For context see:
https://groups.google.com/forum/#!msg/syzkaller/etg1ZJmTMzg/NYE-yjxxAQAJ
https://groups.google.com/d/msg/syzkaller/8KjCYWslTFY/1oTXn5tTAgAJ

Fixes #478

1 files changed, 10 insertions, 41 deletions

diff --git a/Makefile b/Makefile
index 1494d9328..a68edf5fd 100644
--- a/Makefile
+++ b/Makefile
@@ -17,9 +17,9 @@
 # To test x86 compat syscalls, run:
 #    make TARGETVMARCH=amd64 TARGETARCH=386
 #
-# There is a special case for Android builds:
-#    NDK=/path/to/android/ndk make TARGETOS=android TARGETARCH=arm64
-# But you still need to specify "target": "linux/arm64" in syz-manager config.
+# There is one special case for extracting constants for Android
+# (you don't need this unless you update system call descriptions):
+#    make extract TARGETOS=android SOURCEDIR=/path/to/android/checkout
 
 BUILDOS := $(shell go env GOOS)
 BUILDARCH := $(shell go env GOARCH)
@@ -28,7 +28,6 @@ HOSTARCH ?= $(BUILDARCH)
 TARGETOS ?= $(HOSTOS)
 TARGETARCH ?= $(HOSTARCH)
 TARGETVMARCH ?= $(TARGETARCH)
-EXTRACTOS := $(TARGETOS)
 GO := go
 EXE :=
 
@@ -46,40 +45,6 @@ else ifeq ("$(TARGETARCH)", "ppc64le")
 	CC = "powerpc64le-linux-gnu-gcc"
 endif
 
-ifeq ("$(TARGETOS)", "android")
-	EXTRACTOS = android
-	override TARGETOS = linux
-	ANDROID_API = 24
-	BUILDGCCARCH = ""
-	ANDROIDARCH = ""
-	TOOLCHAIN = ""
-	GCCBIN = ""
-	ifeq ("$(TARGETARCH)", "amd64")
-		ANDROIDARCH = "x86_64"
-		TOOLCHAIN = "x86_64-4.9"
-		GCCBIN = "x86_64-linux-android-g++"
-	else ifeq ("$(TARGETARCH)", "386")
-		ANDROIDARCH = "x86"
-		TOOLCHAIN = "x86-4.9"
-		GCCBIN = "i686-linux-android-g++"
-	else ifeq ("$(TARGETARCH)", "arm64")
-		ANDROIDARCH = "arm64"
-		TOOLCHAIN = "aarch64-linux-android-4.9"
-		GCCBIN = "aarch64-linux-android-g++"
-	else ifeq ("$(TARGETARCH)", "arm")
-		ANDROIDARCH = "arm"
-		TOOLCHAIN = "arm-linux-androideabi-4.9"
-		GCCBIN = "arm-linux-androideabi-g++"
-	endif
-	ifeq ("$(BUILDARCH)", "amd64")
-		BUILDGCCARCH = "x86_64"
-	else ifeq ("$(BUILDARCH)", "arm64")
-		BUILDGCCARCH = "aarch64"
-	endif
-	CC = $(NDK)/toolchains/$(TOOLCHAIN)/prebuilt/$(BUILDOS)-$(BUILDGCCARCH)/bin/$(GCCBIN)
-	CFLAGS = -I $(NDK)/sources/cxx-stl/llvm-libc++/include --sysroot=$(NDK)/platforms/android-$(ANDROID_API)/arch-$(ANDROIDARCH) -static
-endif
-
 ifeq ("$(TARGETOS)", "fuchsia")
 	# SOURCEDIR should point to fuchsia checkout.
 	GO = $(SOURCEDIR)/buildtools/go
@@ -122,6 +87,9 @@ endif
 # That's only needed if you use gdb or nm.
 # If you need that, build manually without these flags.
 GOFLAGS := "-ldflags=-s -w -X github.com/google/syzkaller/sys.GitRevision=$(REV)"
+# Build all Go binaries as static. We don't need cgo and it is known to cause
+# problems at least on Android emulator.
+export CGO_ENABLED=0
 ifneq ("$(GOTAGS)", "")
 	GOFLAGS += "-tags=$(GOTAGS)"
 endif
@@ -188,7 +156,7 @@ upgrade:
 	GOOS=$(HOSTOS) GOARCH=$(HOSTARCH) $(GO) build $(GOFLAGS) -o ./bin/syz-upgrade github.com/google/syzkaller/tools/syz-upgrade
 
 extract: bin/syz-extract
-	bin/syz-extract -build -os=$(EXTRACTOS) -sourcedir=$(SOURCEDIR)
+	bin/syz-extract -build -os=$(TARGETOS) -sourcedir=$(SOURCEDIR)
 bin/syz-extract:
 	$(GO) build $(GOFLAGS) -o $@ ./sys/syz-extract
 
@@ -219,8 +187,9 @@ tidy:
 	$(CC) executor/test_executor.cc -c -o /dev/null -Wparentheses -Wno-unused -Wall
 
 test:
-	$(GO) test -short ./...
-	$(GO) test -short -race -bench=.* ./...
+	# Executor tests use cgo.
+	env CGO_ENABLED=1 $(GO) test -short ./...
+	env CGO_ENABLED=1 $(GO) test -short -race -bench=.* ./...
 
 arch:
 	env GOOG=darwin GOARCH=amd64 go install github.com/google/syzkaller/syz-manager