This patch set adds BTF generation for kernel modules using a compact split BTF approach. Respective patches have all the details. Kernel module BTFs rely on pahole's split BTF support, which is added in [0] and will be available starting from v1.19. Support for it is detected automatically during kernel build time. This patch set implements in-kernel support for split BTF loading and validation. It also extends GET_OBJ_INFO API for BTFs to return BTF's module name and a flag whether BTF itself is in-kernel or user-provided. vmlinux BTF is also exposed to user-space through the same BTF object iteration APIs. Follow up patch set will utilize the fact that vmlinux and module BTFs now have associated ID to provide ability to attach BPF fentry/fexit/etc programs to functions defined in kernel modules. bpftool is also extended to show module/vmlinux BTF's name. [0] https://patchwork.kernel.org/project/netdevbpf/list/?series=378699&state=* v2->v1: - drop WARNs, add fewer pr_warn()'s instead (Greg); - properly initialize sysfs binary attribute structure (Greg); - add __maybe_unused to any_section_objs, used conditionally by module BTF; rfc->v1: - CONFIG_DEBUG_INFO_BTF_MODULES is derived automatically (Alexei); - vmlinux BTF now has explicit "vmlinux" name (Alexei); - added sysfs ABI documentation for /sys/kernel/btf/<module> (Greg). Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Andrii Nakryiko (5): bpf: add in-kernel split BTF support bpf: assign ID to vmlinux BTF and return extra info for BTF in GET_OBJ_INFO kbuild: build kernel module BTFs if BTF is enabled and pahole supports it bpf: load and verify kernel module BTFs tools/bpftool: add support for in-kernel and named BTF in `btf show` Documentation/ABI/testing/sysfs-kernel-btf | 8 + include/linux/bpf.h | 2 + include/linux/module.h | 4 + include/uapi/linux/bpf.h | 3 + kernel/bpf/btf.c | 413 ++++++++++++++++++--- kernel/bpf/sysfs_btf.c | 2 +- kernel/module.c | 32 ++ lib/Kconfig.debug | 9 + scripts/Makefile.modfinal | 20 +- tools/bpf/bpftool/btf.c | 28 +- tools/include/uapi/linux/bpf.h | 3 + 11 files changed, 467 insertions(+), 57 deletions(-) -- 2.24.1
