Support creation of module BTF along with distilled base BTF; the latter is stored in a .BTF.base ELF section and supplements split BTF references to base BTF with information about base types, allowing for later relocation of split BTF with a (possibly changed) base. resolve_btfids uses the "-B" option to specify that the BTF.ids section should be populated with split BTF relative to the added .BTF.base section rather than relative to the vmlinux base. Modules will be built with a distilled .BTF.base section for external module build, i.e. make -C. -M=path2/module ...while in-tree module build as part of a normal kernel build will not generate distilled base BTF; this is because in-tree modules change with the kernel and do not require BTF relocation for the running vmlinux. Signed-off-by: Alan Maguire <alan.maguire@xxxxxxxxxx> --- scripts/Makefile.btf | 7 +++++++ scripts/Makefile.modfinal | 4 ++-- 2 files changed, 9 insertions(+), 2 deletions(-) diff --git a/scripts/Makefile.btf b/scripts/Makefile.btf index bca8a8f26ea4..9f1e3163e718 100644 --- a/scripts/Makefile.btf +++ b/scripts/Makefile.btf @@ -21,8 +21,15 @@ else # Switch to using --btf_features for v1.26 and later. pahole-flags-$(call test-ge, $(pahole-ver), 126) = -j --btf_features=encode_force,var,float,enum64,decl_tag,type_tag,optimized_func,consistent_func +ifneq ($(KBUILD_EXTMOD),) +module-pahole-flags-$(call test-ge, $(pahole-ver), 126) += --btf_features=distilled_base +module-resolve-btfids-flags-$(call test-ge, $(pahole-ver), 126) = -B +endif + endif pahole-flags-$(CONFIG_PAHOLE_HAS_LANG_EXCLUDE) += --lang_exclude=rust export PAHOLE_FLAGS := $(pahole-flags-y) +export MODULE_PAHOLE_FLAGS := $(module-pahole-flags-y) +export MODULE_RESOLVE_BTFIDS_FLAGS := $(module-resolve-btfids-flags-y) diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal index 79fcf2731686..86189ddf39e8 100644 --- a/scripts/Makefile.modfinal +++ b/scripts/Makefile.modfinal @@ -39,8 +39,8 @@ quiet_cmd_btf_ko = BTF [M] $@ if [ ! -f vmlinux ]; then \ printf "Skipping BTF generation for %s due to unavailability of vmlinux\n" $@ 1>&2; \ else \ - LLVM_OBJCOPY="$(OBJCOPY)" $(PAHOLE) -J $(PAHOLE_FLAGS) --btf_base vmlinux $@; \ - $(RESOLVE_BTFIDS) -b vmlinux $@; \ + LLVM_OBJCOPY="$(OBJCOPY)" $(PAHOLE) -J $(PAHOLE_FLAGS) $(MODULE_PAHOLE_FLAGS) --btf_base vmlinux $@; \ + $(RESOLVE_BTFIDS) $(MODULE_RESOLVE_BTFIDS_FLAGS) -b vmlinux $@; \ fi; # Same as newer-prereqs, but allows to exclude specified extra dependencies -- 2.31.1
