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 detects the presence of a .BTF.base section and will use it instead of the base BTF it is passed in BTF id resolution. 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> Reviewed-by: Eduard Zingerman <eddyz87@xxxxxxxxx> --- scripts/Makefile.btf | 5 +++++ scripts/Makefile.modfinal | 2 +- 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/scripts/Makefile.btf b/scripts/Makefile.btf index 2597e3d4d6e0..b75f09f3f424 100644 --- a/scripts/Makefile.btf +++ b/scripts/Makefile.btf @@ -21,8 +21,13 @@ else # Switch to using --btf_features for v1.26 and later. pahole-flags-$(call test-ge, $(pahole-ver), 126) = -j --btf_features=encode_force,var,float,enum64,decl_tag,type_tag,optimized_func,consistent_func,decl_tag_kfuncs +ifneq ($(KBUILD_EXTMOD),) +module-pahole-flags-$(call test-ge, $(pahole-ver), 126) += --btf_features=distilled_base +endif + endif pahole-flags-$(CONFIG_PAHOLE_HAS_LANG_EXCLUDE) += --lang_exclude=rust export PAHOLE_FLAGS := $(pahole-flags-y) +export MODULE_PAHOLE_FLAGS := $(module-pahole-flags-y) diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal index 3bec9043e4f3..1fa98b5e952b 100644 --- a/scripts/Makefile.modfinal +++ b/scripts/Makefile.modfinal @@ -41,7 +41,7 @@ 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 $@; \ + LLVM_OBJCOPY="$(OBJCOPY)" $(PAHOLE) -J $(PAHOLE_FLAGS) $(MODULE_PAHOLE_FLAGS) --btf_base vmlinux $@; \ $(RESOLVE_BTFIDS) -b vmlinux $@; \ fi; -- 2.31.1
