support/testing: add bpftrace test

This commit adds a simple bpftrace test that ensures that not only it
builds fine, but it also runs properly on a minimal test scenario.

Assisted-by: GPT-5.6
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
[Julien:
 - reindent emulator.boot() options
 - add a call to "bpftrace --version"
]
Signed-off-by: Julien Olivain <ju.o@free.fr>

DEVELOPERS

@@ -3304,6 +3304,8 @@ F:	support/testing/tests/package/sample_python_flask_expects_json.py
 F:	support/testing/tests/package/sample_python_git.py
 F:	support/testing/tests/package/sample_python_pyudev.py
 F:	support/testing/tests/package/sample_python_unittest_xml_reporting.py
+F:	support/testing/tests/package/test_bpftrace.py
+F:	support/testing/tests/package/test_bpftrace/linux-bpftrace.fragment
 F:	support/testing/tests/package/test_nodejs.py
 F:	support/testing/tests/package/test_python_augeas.py
 F:	support/testing/tests/package/test_python_crccheck.py

support/testing/tests/package/test_bpftrace.py

@@ -0,0 +1,65 @@
+import os
+
+import infra.basetest
+
+
+# gitlab-runner: 2xlarge
+class TestBpftrace(infra.basetest.BRTest):
+    kern_fragment = infra.filepath(
+        "tests/package/test_bpftrace/linux-bpftrace.fragment"
+    )
+    config = f"""
+        BR2_aarch64=y
+        BR2_TOOLCHAIN_EXTERNAL=y
+        BR2_TARGET_GENERIC_GETTY_PORT="ttyAMA0"
+        BR2_LINUX_KERNEL=y
+        BR2_LINUX_KERNEL_CUSTOM_VERSION=y
+        BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="6.6.32"
+        BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG=y
+        BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="board/qemu/aarch64-virt/linux.config"
+        BR2_LINUX_KERNEL_CONFIG_FRAGMENT_FILES="{kern_fragment}"
+        BR2_LINUX_KERNEL_NEEDS_HOST_OPENSSL=y
+        BR2_PACKAGE_BUSYBOX_SHOW_OTHERS=y
+        BR2_PACKAGE_BPFTRACE=y
+        BR2_PACKAGE_TAR=y
+        BR2_TARGET_ROOTFS_EXT2=y
+        BR2_TARGET_ROOTFS_EXT2_4=y
+        BR2_TARGET_ROOTFS_EXT2_SIZE="256M"
+        # BR2_TARGET_ROOTFS_TAR is not set
+        """
+
+    def test_run(self):
+        drive = os.path.join(self.builddir, "images", "rootfs.ext4")
+        kern = os.path.join(self.builddir, "images", "Image")
+        self.emulator.boot(
+            arch="aarch64",
+            kernel=kern,
+            kernel_cmdline=["root=/dev/vda console=ttyAMA0"],
+            options=[
+                "-M", "virt",
+                "-cpu", "cortex-a57",
+                "-m", "256M",
+                "-drive", f"file={drive},if=virtio,format=raw"
+            ]
+        )
+        self.emulator.login()
+
+        self.assertRunOk("mount -t debugfs none /sys/kernel/debug/")
+
+        # Check the program can run.
+        self.assertRunOk("bpftrace --version")
+
+        # Check that bpftrace can find a syscall tracepoint.
+        self.assertRunOk("bpftrace -l 'tracepoint:syscalls:sys_enter_execve'")
+
+        # Compile and attach a tracepoint program, then trigger it with the
+        # command executed by bpftrace. The marker avoids matching volatile
+        # fields such as PIDs or command names.
+        cmd = (
+            "bpftrace -e 'tracepoint:syscalls:sys_enter_execve "
+            '{ printf("buildroot-bpftrace-test\\n"); exit(); }\' '
+            "-c /bin/true"
+        )
+        output, ret = self.emulator.run(cmd)
+        self.assertEqual(ret, 0)
+        self.assertIn("buildroot-bpftrace-test", "\n".join(output))

support/testing/tests/package/test_bpftrace/linux-bpftrace.fragment

@@ -0,0 +1,4 @@
+CONFIG_FTRACE=y
+CONFIG_FTRACE_SYSCALLS=y
+CONFIG_FUNCTION_TRACER=y
+CONFIG_KPROBES=y