🛸 Sync 2026-07-04 19:06:12

2026-09-11 19:05:11 +08:00 · 2026-07-04 19:06:12 +08:00
parent 0ec008c9bf
commit 673a352ca1
20 changed files with 126 additions and 676 deletions
@@ -0,0 +1,125 @@
+# SPDX-License-Identifier: GPL-3.0-only
+#
+# Detached kernel BTF for CO-RE eBPF (dae/daed) on firmware whose kernel was
+# built without CONFIG_DEBUG_INFO_BTF. Builds a shadow kernel from the same
+# OpenWrt source + .config with BTF enabled, then pahole-encodes a detached
+# vmlinux.btf. cilium/ebpf finds it at /usr/lib/debug/boot/vmlinux-<release>.
+
+include $(TOPDIR)/rules.mk
+include $(INCLUDE_DIR)/kernel.mk
+
+PKG_NAME:=vmlinux-btf
+PKG_VERSION:=$(LINUX_VERSION)
+PKG_RELEASE:=1
+
+include $(INCLUDE_DIR)/package.mk
+
+PKG_BUILD_PARALLEL:=1
+
+define Package/vmlinux-btf
+  SECTION:=kernel
+  CATEGORY:=Kernel
+  TITLE:=Kernel vmlinux.btf for CO-RE compatibility
+endef
+
+define Package/vmlinux-btf/description
+  Supplies detached kernel BTF so CO-RE eBPF programs (dae/daed) load on
+  kernels built without CONFIG_DEBUG_INFO_BTF. Builds a shadow kernel from the
+  OpenWrt kernel source with BTF enabled and encodes a detached vmlinux.btf.
+endef
+
+define Package/vmlinux-btf/postinst
+#!/bin/sh
+if [ -z "$${IPKG_INSTROOT}" ]; then
+	ln -sf /usr/lib/debug/boot/vmlinux /usr/lib/debug/boot/vmlinux-$$(uname -r)
+fi
+endef
+
+define Package/vmlinux-btf/prerm
+#!/bin/sh
+if [ -z "$${IPKG_INSTROOT}" ]; then
+	rm -f /usr/lib/debug/boot/vmlinux-$$(uname -r)
+fi
+endef
+
+PAHOLE_JOBS := $(if $(filter -j%,$(PKG_JOBS)),$(patsubst -j%,%,$(filter -j%,$(PKG_JOBS))),1)
+
+# The SDK ships an extracted kernel but no dl/ tarball, so fetch vanilla source.
+KERNEL_MAJOR:=$(firstword $(subst ., ,$(LINUX_VERSION)))
+LINUX_TARBALL_URL:=https://cdn.kernel.org/pub/linux/kernel/v$(KERNEL_MAJOR).x/$(LINUX_SOURCE)
+
+define Build/Prepare
+	mkdir -p $(PKG_BUILD_DIR) $(DL_DIR)
+	[ -f "$(DL_DIR)/$(LINUX_SOURCE)" ] || \
+		wget -nv -O "$(DL_DIR)/$(LINUX_SOURCE)" "$(LINUX_TARBALL_URL)"
+	$(TAR) -C $(PKG_BUILD_DIR) -xf $(DL_DIR)/$(LINUX_SOURCE)
+	mv $(PKG_BUILD_DIR)/linux-$(LINUX_VERSION) $(PKG_BUILD_DIR)/shadow-kernel
+	cp $(LINUX_DIR)/.config $(PKG_BUILD_DIR)/shadow-kernel/.config
+endef
+
+define Build/Compile
+	$(PKG_BUILD_DIR)/shadow-kernel/scripts/config \
+		--file $(PKG_BUILD_DIR)/shadow-kernel/.config \
+		--disable WERROR \
+		--enable CGROUPS \
+		--enable CGROUP_BPF \
+		--enable SOCK_CGROUP_DATA \
+		--enable KALLSYMS \
+		--enable PERF_EVENTS \
+		--enable TRACEPOINTS \
+		--enable KPROBES \
+		--enable UPROBES \
+		--enable BPF \
+		--enable BPF_SYSCALL \
+		--enable BPF_JIT \
+		--enable BPF_JIT_DEFAULT_ON \
+		--enable INET \
+		--enable NET_INGRESS \
+		--enable NET_EGRESS \
+		--enable BPF_STREAM_PARSER \
+		--enable XDP_SOCKETS \
+		--enable NET_SCHED \
+		--enable NET_SCH_INGRESS \
+		--enable NET_CLS \
+		--enable NET_CLS_ACT \
+		--enable KPROBE_EVENTS \
+		--enable UPROBE_EVENTS \
+		--enable BPF_EVENTS \
+		--enable DEBUG_KERNEL \
+		--enable DEBUG_INFO \
+		--disable DEBUG_INFO_NONE \
+		--enable DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT \
+		--disable DEBUG_INFO_REDUCED \
+		--disable DEBUG_INFO_SPLIT \
+		--enable DEBUG_INFO_BTF \
+		--set-str EXTRA_FIRMWARE "" \
+		--set-str INITRAMFS_SOURCE ""
+
+	$(MAKE) -C $(PKG_BUILD_DIR)/shadow-kernel \
+		$(KERNEL_MAKE_FLAGS) \
+		KBUILD_HOSTLDFLAGS="$(KBUILD_HOSTLDFLAGS) -lz" \
+		olddefconfig
+
+	$(MAKE) -C $(PKG_BUILD_DIR)/shadow-kernel \
+		$(KERNEL_MAKE_FLAGS) \
+		$(PKG_JOBS) \
+		KBUILD_HOSTLDFLAGS="-L$(STAGING_DIR_HOST)/lib -lz" \
+		vmlinux
+
+	pahole \
+		--jobs=$(PAHOLE_JOBS) \
+		--btf_encode_detached=$(PKG_BUILD_DIR)/vmlinux-btf \
+		$(PKG_BUILD_DIR)/shadow-kernel/vmlinux
+endef
+
+define Build/Clean
+	rm -rf $(PKG_BUILD_DIR)
+endef
+
+define Package/vmlinux-btf/install
+	$(INSTALL_DIR) $(1)/usr/lib/debug/boot
+	$(INSTALL_DATA) $(PKG_BUILD_DIR)/vmlinux-btf $(1)/usr/lib/debug/boot/vmlinux
+	$(LN) vmlinux $(1)/usr/lib/debug/boot/vmlinux-$(LINUX_VERSION)
+endef
+
+$(eval $(call BuildPackage,vmlinux-btf))