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Viktor Malik a6de3213c4 kbuild,bpf: Add module-specific pahole flags for distilled base BTF
JIRA: https://issues.redhat.com/browse/RHEL-30774

Conflicts: changed context due to missing upstream commits
           2f7ab1267dc9b ("Kbuild: add Rust support")
           41bdc6decda07 ("btf, scripts: rust: drop is_rust_module.sh")

commit 46fb0b62ea29c0dbcb3e44f1d67aafe79bc6e045
Author: Alan Maguire <alan.maguire@oracle.com>
Date:   Thu Jun 20 10:17:32 2024 +0100

    kbuild,bpf: Add module-specific pahole flags for distilled base BTF

    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@oracle.com>
    Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
    Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
    Link: https://lore.kernel.org/bpf/20240620091733.1967885-6-alan.maguire@oracle.com

Signed-off-by: Viktor Malik <vmalik@redhat.com>
2024-11-26 15:55:10 +01:00

82 lines
2.7 KiB
Makefile

# SPDX-License-Identifier: GPL-2.0-only
# ===========================================================================
# Module final link
# ===========================================================================
PHONY := __modfinal
__modfinal:
include include/config/auto.conf
include $(srctree)/scripts/Kbuild.include
# for c_flags
include $(srctree)/scripts/Makefile.lib
# find all modules listed in modules.order
modules := $(sort $(shell cat $(MODORDER)))
__modfinal: $(modules)
@:
# modname and part-of-module are set to make c_flags define proper module flags
modname = $(notdir $(@:.mod.o=))
part-of-module = y
quiet_cmd_cc_o_c = CC [M] $@
cmd_cc_o_c = $(CC) $(filter-out $(CC_FLAGS_CFI) $(CFLAGS_GCOV), $(c_flags)) -c -o $@ $<
%.mod.o: %.mod.c FORCE
$(call if_changed_dep,cc_o_c)
ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)
quiet_cmd_ld_ko_o = LD [M] $@
cmd_ld_ko_o += \
$(LD) -r $(KBUILD_LDFLAGS) \
$(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE) \
-T scripts/module.lds -o $@ $(filter %.o, $^); \
$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
quiet_cmd_btf_ko = BTF [M] $@
cmd_btf_ko = \
if [ -f vmlinux ]; then \
LLVM_OBJCOPY="$(OBJCOPY)" $(PAHOLE) -J $(PAHOLE_FLAGS) $(MODULE_PAHOLE_FLAGS) --btf_base vmlinux $@; \
$(RESOLVE_BTFIDS) -b vmlinux $@; \
else \
printf "Skipping BTF generation for %s due to unavailability of vmlinux\n" $@ 1>&2; \
fi;
# Same as newer-prereqs, but allows to exclude specified extra dependencies
newer_prereqs_except = $(filter-out $(PHONY) $(1),$?)
# Same as if_changed, but allows to exclude specified extra dependencies
if_changed_except = $(if $(call newer_prereqs_except,$(2))$(cmd-check), \
$(cmd); \
printf '%s\n' 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd, @:)
# Re-generate module BTFs if either module's .ko or vmlinux changed
$(modules): %.ko: %.o %.mod.o scripts/module.lds $(if $(KBUILD_BUILTIN),vmlinux) FORCE
+$(call if_changed_except,ld_ko_o,vmlinux)
ifdef CONFIG_DEBUG_INFO_BTF_MODULES
+$(if $(newer-prereqs),$(call cmd,btf_ko))
endif
targets += $(modules) $(modules:.ko=.mod.o)
# Add FORCE to the prequisites of a target to force it to be always rebuilt.
# ---------------------------------------------------------------------------
PHONY += FORCE
FORCE:
# Read all saved command lines and dependencies for the $(targets) we
# may be building above, using $(if_changed{,_dep}). As an
# optimization, we don't need to read them if the target does not
# exist, we will rebuild anyway in that case.
existing-targets := $(wildcard $(sort $(targets)))
-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
.PHONY: $(PHONY)