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.
Unified · Split
| @@ -21,8 +21,13 @@ else · 20 unmodified lines | ||
| 21 | 21 | # Switch to using --btf_features for v1.26 and later. |
| 22 | 22 | pahole-flags-$(call test-ge, $(pahole-ver), 126) = -j --btf_features=encode_force,var,float,enum64,decl_tag,type_tag,optimized_func,consistent_func,decl_tag_kfuncs |
| 23 | 23 | |
| 24 | +ifneq ($(KBUILD_EXTMOD),) | |
| 25 | +module-pahole-flags-$(call test-ge, $(pahole-ver), 126) += --btf_features=distilled_base | |
| 26 | +endif | |
| 27 | + | |
| 24 | 28 | endif |
| 25 | 29 | |
| 26 | 30 | pahole-flags-$(CONFIG_PAHOLE_HAS_LANG_EXCLUDE) += --lang_exclude=rust |
| 27 | 31 | |
| 28 | 32 | export PAHOLE_FLAGS := $(pahole-flags-y) |
| 33 | +export MODULE_PAHOLE_FLAGS := $(module-pahole-flags-y) | |
| @@ -41,7 +41,7 @@ quiet_cmd_btf_ko = BTF [M] $@ · 40 unmodified lines | ||
| 41 | 41 | if [ ! -f vmlinux ]; then \ |
| 42 | 42 | printf "Skipping BTF generation for %s due to unavailability of vmlinux\n" $@ 1>&2; \ |
| 43 | 43 | else \ |
| 44 | − LLVM_OBJCOPY="$(OBJCOPY)" $(PAHOLE) -J $(PAHOLE_FLAGS) --btf_base vmlinux $@; \ | |
| 44 | + LLVM_OBJCOPY="$(OBJCOPY)" $(PAHOLE) -J $(PAHOLE_FLAGS) $(MODULE_PAHOLE_FLAGS) --btf_base vmlinux $@; \ | |
| 45 | 45 | $(RESOLVE_BTFIDS) -b vmlinux $@; \ |
| 46 | 46 | fi; |
| 47 | 47 | |