Add support for cross-compiling via the Makefile (#80)

Dockerfile

@@ -2,14 +2,19 @@ FROM debian:testing
 
 WORKDIR /agent
 
-ARG arch=amd64
-
-RUN apt-get update -y && apt-get dist-upgrade -y && apt-get install -y \
-    curl wget cmake dwz lsb-release software-properties-common gnupg git clang-16 llvm \
-    golang unzip jq && apt-get clean autoclean && apt-get autoremove --yes
-
-RUN wget -qO- https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s -- -b $(go env GOPATH)/bin v1.56.2
-
+# cross_debian_arch: amd64 or arm64
+# cross_pkg_arch: x86-64 or aarch64
+RUN cross_debian_arch=$(uname -m | sed -e 's/aarch64/amd64/'  -e 's/x86_64/arm64/'); \
+    cross_pkg_arch=$(uname -m | sed -e 's/aarch64/x86-64/' -e 's/x86_64/aarch64/'); \
+    apt-get update -y && \
+    apt-get dist-upgrade -y && \
+    apt-get install -y wget make git clang-16 golang unzip \
+        gcc-${cross_pkg_arch}-linux-gnu libc6-${cross_debian_arch}-cross && \
+    apt-get clean autoclean && \
+    apt-get autoremove --yes
+
+RUN wget -qO- https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh \
+    | sh -s -- -b $(go env GOPATH)/bin v1.56.2
 
 # gRPC dependencies
 RUN go install google.golang.org/protobuf/cmd/[email protected]
@@ -20,7 +25,7 @@ RUN
   PB_FILE="protoc-24.4-linux-x86_64.zip";                                      \
   INSTALL_DIR="/usr/local";                                                        \
                                                                                    \
-  curl -LO "$PB_URL/$PB_FILE"                                                      \
+  wget -q "$PB_URL/$PB_FILE"                                                       \
     && unzip "$PB_FILE" -d "$INSTALL_DIR" 'bin/*' 'include/*'                      \
     && chmod +xr "$INSTALL_DIR/bin/protoc"                                         \
     && find "$INSTALL_DIR/include" -type d -exec chmod +x {} \;                    \

Makefile

@@ -3,16 +3,48 @@
 
 SHELL := /usr/bin/env bash
 
+# Detect native architecture and translate to GOARCH.
+NATIVE_ARCH := $(shell uname -m)
+ifeq ($(NATIVE_ARCH),x86_64)
+NATIVE_ARCH := amd64
+else ifneq (,$(filter $(NATIVE_ARCH),aarch64 arm64))
+NATIVE_ARCH := arm64
+else
+$(error Unsupported architecture: $(NATIVE_ARCH))
+endif
+
+# Valid values are: amd64, arm64.
+TARGET_ARCH ?= $(NATIVE_ARCH)
+
+ifeq ($(NATIVE_ARCH),$(TARGET_ARCH))
+ARCH_PREFIX :=
+else ifeq ($(TARGET_ARCH),arm64)
+ARCH_PREFIX := aarch64-linux-gnu-
+else ifeq ($(TARGET_ARCH),amd64)
+ARCH_PREFIX := x86_64-linux-gnu-
+else
+$(error Unsupported architecture: $(TARGET_ARCH))
+endif
+
+export TARGET_ARCH
+export CGO_ENABLED = 1
+export GOARCH = $(TARGET_ARCH)
+export CC = $(ARCH_PREFIX)gcc
+export OBJCOPY = $(ARCH_PREFIX)objcopy
+
 BRANCH = $(shell git rev-parse --abbrev-ref HEAD | tr -d '-' | tr '[:upper:]' '[:lower:]')
 COMMIT_SHORT_SHA = $(shell git rev-parse --short=8 HEAD)
 
 VERSION ?= v0.0.0
 BUILD_TIMESTAMP ?= $(shell date +%s)
 REVISION ?= $(BRANCH)-$(COMMIT_SHORT_SHA)
 
-VC_LDFLAGS := -X github.com/elastic/otel-profiling-agent/vc.version=$(VERSION) \
+LDFLAGS := -X github.com/elastic/otel-profiling-agent/vc.version=$(VERSION) \
 	-X github.com/elastic/otel-profiling-agent/vc.revision=$(REVISION) \
-	-X github.com/elastic/otel-profiling-agent/vc.buildTimestamp=$(BUILD_TIMESTAMP)
+	-X github.com/elastic/otel-profiling-agent/vc.buildTimestamp=$(BUILD_TIMESTAMP) \
+	-extldflags=-static
+
+GO_FLAGS := -buildvcs=false -ldflags="$(LDFLAGS)" -tags osusergo,netgo
 
 all: generate ebpf binary
 
@@ -25,11 +57,10 @@ clean:
 	@rm -rf go .cache
 
 generate:
-	go install github.com/florianl/[email protected]
 	go generate ./...
 
 binary:
-	go build -buildvcs=false -ldflags="$(VC_LDFLAGS) -extldflags=-static" -tags osusergo,netgo
+	go build $(GO_FLAGS)
 
 ebpf:
 	$(MAKE) -j$(shell nproc) -C support/ebpf
@@ -40,7 +71,7 @@ lint: generate
 	golangci-lint run --timeout 10m
 
 test: generate ebpf test-deps
-	go test ./...
+	go test $(GO_FLAGS) ./...
 
 TESTDATA_DIRS:= \
 	nativeunwind/elfunwindinfo/testdata \
@@ -62,23 +93,12 @@ integration-test-binaries: generate ebpf
 			./$(test_name)) || exit ; \
 	)
 
-# Detect native architecture.
-UNAME_NATIVE_ARCH:=$(shell uname -m)
-
-ifeq ($(UNAME_NATIVE_ARCH),x86_64)
-NATIVE_ARCH:=amd64
-else ifneq (,$(filter $(UNAME_NATIVE_ARCH),aarch64 arm64))
-NATIVE_ARCH:=arm64
-else
-$(error Unsupported architecture: $(UNAME_NATIVE_ARCH))
-endif
-
 docker-image:
-	docker build -t profiling-agent --build-arg arch=$(NATIVE_ARCH) -f Dockerfile .
+	docker build -t profiling-agent -f Dockerfile .
 
 agent:
 	docker run -v "$$PWD":/agent -it --rm --user $(shell id -u):$(shell id -g) profiling-agent \
-		make VERSION=$(VERSION) REVISION=$(REVISION) BUILD_TIMESTAMP=$(BUILD_TIMESTAMP)
+	   "make TARGET_ARCH=$(TARGET_ARCH) VERSION=$(VERSION) REVISION=$(REVISION) BUILD_TIMESTAMP=$(BUILD_TIMESTAMP)"
 
 legal:
 	@go install go.elastic.co/go-licence-detector@latest

README.md

@@ -1,5 +1,5 @@
-> [!NOTE] 
-> 
+> [!NOTE]
+>
 > Please be aware that we currently won't merge 3rd party PRs because this repository
 > is temporary. We are waiting for the decision of the OpenTelemetry technical
 > commitee on the donation of this repository.
@@ -42,8 +42,8 @@ agent to OpenTelementry.
 
 ## Building
 
-> [!NOTE] 
-> 
+> [!NOTE]
+>
 > If you simply wish to take the agent for a spin with minimal effort, you can
 > also immediately jump to the ["Visualizing data locally"
 > section](#visualizing-data-locally), launch devfiler and follow the download
@@ -60,7 +60,11 @@ make docker-image
 
 Then, you can build the agent:
 ```sh
+# Build for architecture of current machine:
 make agent
+
+# OR, cross-compile an agent for another architecture:
+make agent TARGET_ARCH=arm64 # accepted: amd64, arm64
 ```
 
 The resulting binary will be in the current directory as `otel-profiling-agent`.
@@ -86,7 +90,7 @@ captured traces to the backend.
 ## Visualizing data locally
 
 We created a desktop application called "devfiler" that allows visualizing the
-profiling agent's output locally, making it very convenient for development use. 
+profiling agent's output locally, making it very convenient for development use.
 devfiler spins up a local server that listens on `0.0.0.0:11000`.
 
 ![Screenshot of devfiler UI](./doc/devfiler.png)
@@ -104,7 +108,7 @@ The archive contains a build for each of the following platforms:
 - Linux AppImage (x86_64)
 - Linux AppImage (aarch64)
 
-> [!NOTE] 
+> [!NOTE]
 > devfiler is currently in an experimental preview stage.
 
 ### macOS

libpf/pfelf/testdata/Makefile

@@ -1,5 +1,8 @@
 .PHONY: all
 
+CC ?= cc
+OBJCOPY ?= objcopy
+
 BINARIES=fixed-address \
 	go-binary \
 	kernel-image \
@@ -15,18 +18,18 @@ clean:
 	rm -f $(BINARIES)
 
 with-debug-syms: test.c
-	gcc $< -g -o $@
+	$(CC) $< -g -o $@
 
 without-debug-syms: test.c
-	gcc $< -s -o $@
+	$(CC) $< -s -o $@
 
 separate-debug-file: with-debug-syms
-	objcopy --only-keep-debug $< $@
+	$(OBJCOPY) --only-keep-debug $< $@
 
 fixed-address: fixed-address.c fixed-address.ld
 	# The following command will likely print a warning (about a missing -T option), which should be ignored.
 	# Removing the warning would require passing a fully-fledged linker script to bypass gcc's default.
-	gcc $^ -o $@
+	$(CC) $^ -o $@
 
 # Write an ELF notes file with a build ID
 the_notorious_build_id:
@@ -36,12 +39,12 @@ the_notorious_build_id:
 	bash -c "echo -en 'somedata\x04\x00\x00\x00\x14\x00\x00\x00\x03\x00\x00\x00GNU\x00_notorious_build_id_\x00somedata' > $@"
 
 kernel-image: test.c
-	gcc $< -s -o $@ -DLINUX_VERSION="\"Linux version 1.2.3\\n\""
+	$(CC) $< -s -o $@ -DLINUX_VERSION="\"Linux version 1.2.3\\n\""
 
 ubuntu-kernel-image: test.c
-	gcc $< -s -o $@ -DLINUX_VERSION="\"Linux version 1.2.3 (Ubuntu 4.5.6)\\n\""
+	$(CC) $< -s -o $@ -DLINUX_VERSION="\"Linux version 1.2.3 (Ubuntu 4.5.6)\\n\""
 
 # A fake go binary (with a .gopclntab section)
 go-binary: without-debug-syms
-	objcopy --add-section .gopclntab=/dev/null $< $@
+	$(OBJCOPY) --add-section .gopclntab=/dev/null $< $@
 

reporter/testdata/Makefile

@@ -1,7 +1,7 @@
 .PHONY: all
 
-CC=gcc
-CFLAGS=-Wl,--build-id
+CC ?= cc
+CFLAGS = -Wl,--build-id
 
 all: test
 

support/ebpf/Makefile

@@ -1,28 +1,24 @@
 SHELL ?= bash
-
-CLANG ?= clang-16
-LINK ?= llvm-link-16
+BPF_CLANG ?= clang-16
+BPF_LINK ?= llvm-link-16
 LLC ?= llc-16
 
 DEBUG_FLAGS = -DOPTI_DEBUG -g
 
-# Detect native architecture.
-NATIVE_ARCH:=$(shell uname -m)
-
+# Detect native architecture and translate to GOARCH.
+NATIVE_ARCH := $(shell uname -m)
 ifeq ($(NATIVE_ARCH),x86_64)
-NATIVE_ARCH:=x86
-else ifeq ($(NATIVE_ARCH),aarch64)
-NATIVE_ARCH:=arm64
+NATIVE_ARCH := amd64
+else ifneq (,$(filter $(NATIVE_ARCH),aarch64 arm64))
+NATIVE_ARCH := arm64
 else
 $(error Unsupported architecture: $(NATIVE_ARCH))
 endif
 
-# This can be passed-in, valid values are: x86, arm64.
-target_arch ?= $(NATIVE_ARCH)
+# Valid values are: amd64, arm64.
+TARGET_ARCH ?= $(NATIVE_ARCH)
 
-# Set default values.
-TARGET_ARCH = $(target_arch)
-TRACER_NAME = tracer.ebpf.$(TARGET_ARCH)
+TRACER_NAME ?= tracer.ebpf.$(TARGET_ARCH)
 
 ifeq ($(TARGET_ARCH),arm64)
 TARGET_FLAGS = -target aarch64-linux-gnu
@@ -53,28 +49,28 @@ all: $(TRACER_NAME)
 debug: TARGET_FLAGS+=$(DEBUG_FLAGS)
 debug: all
 
-x86:
-	$(MAKE) target_arch=x86 all
+amd64:
+	$(MAKE) TARGET_ARCH=amd64 all
 
 arm64:
-	$(MAKE) target_arch=arm64 all
+	$(MAKE) TARGET_ARCH=arm64 all
 
-debug-x86:
-	$(MAKE) target_arch=x86 debug
+debug-amd64:
+	$(MAKE) TARGET_ARCH=amd64 debug
 
 debug-arm64:
-	$(MAKE) target_arch=arm64 debug
+	$(MAKE) TARGET_ARCH=arm64 debug
 
 errors.h: ../../tools/errors-codegen/errors.json
 	go run ../../tools/errors-codegen/main.go bpf $@
 
 %.ebpf.c: errors.h ;
 
 %.ebpf.$(TARGET_ARCH).o: %.ebpf.c
-	$(CLANG) $(FLAGS) -o $@
+	$(BPF_CLANG) $(FLAGS) -o $@
 
 $(TRACER_NAME): $(OBJS)
-	$(LINK) $^ -o - | $(LLC) -march=bpf -mcpu=v2 -filetype=obj -o $@
+	$(BPF_LINK) $^ -o - | $(LLC) -march=bpf -mcpu=v2 -filetype=obj -o $@
 	@./print_instruction_count.sh $@
 
 baseline: $(TRACER_NAME)

support/support_amd64.go

@@ -12,5 +12,5 @@ import (
 	_ "embed"
 )
 
-//go:embed ebpf/tracer.ebpf.x86
+//go:embed ebpf/tracer.ebpf.amd64
 var tracerData []byte

tools/fake-apm-agent/Makefile

@@ -1,5 +1,7 @@
 .PHONY: clean all
 
+CC ?= cc
+
 ARCH=$(shell uname -m)
 LIB_NAME=elastic-jvmti-linux-$(ARCH).so
 
@@ -12,10 +14,10 @@ endif
 all: fake-apm-agent $(LIB_NAME)
 
 $(LIB_NAME): fake-apm-agent-lib.c
-	cc $< -g -shared -fPIC -mtls-dialect=$(TLS_DIALECT) -ftls-model=global-dynamic -o $@
+	$(CC) $< -g -shared -fPIC -mtls-dialect=$(TLS_DIALECT) -ftls-model=global-dynamic -o $@
 
 fake-apm-agent: fake-apm-agent.c
-	cc $< -g -DLIB_NAME='"$(LIB_NAME)"' -o $@
+	$(CC) $< -g -DLIB_NAME='"$(LIB_NAME)"' -o $@
 
 clean:
 	rm elastic-jvmti-linux-$(ARCH).so