From: Joao Moreira <jmoreira@xxxxxxx> For automatic resolution of livepatch relocations, a file called symbols.klp is used. This file maps symbols within every compiled kernel object allowing the identification of symbols whose name is unique, thus relocation can be automatically inferred, or providing information that helps developers when code annotation is required for solving the matter. Add support for creating symbols.klp in the main Makefile. First, ensure that built-in is compiled when CONFIG_LIVEPATCH is enabled (as required to achieve a complete symbols.klp file). Define the command to build symbols.klp (cmd_klp_map) and hook it in the modules rule. As it is undesirable to have symbols from livepatch objects inside symbols.klp, make livepatches discernible by modifying scripts/Makefile.build to create a .livepatch file for each livepatch in $(MODVERDIR). This file then used by cmd_klp_map to identify and bypass livepatches. For identifying livepatches during the build process, a flag variable LIVEPATCH_$(basetarget).o is considered in scripts/Makefile.build. This way, set this flag for the livepatch sample Makefile in samples/livepatch/Makefile. Finally, Add a clean rule to ensure that symbols.klp is removed during clean. Notes: To achieve a correct symbols.klp file, all kernel objects must be considered, thus, its construction require these objects to be priorly built. On the other hand, invoking scripts/Makefile.modpost without having a complete symbols.klp in place would occasionally lead to in-tree livepatches being post-processed incorrectly. To prevent this from becoming a circular dependency, the construction of symbols.klp uses non-post-processed kernel objects and such does not cause harm as the symbols normally referenced from within livepatches are visible at this stage. Also due to these requirements, the spot in-between modules compilation and the invocation of scripts/Makefile.modpost was picked for hooking cmd_klp_map. The approach based on .livepatch files was proposed as an alternative to using MODULE_INFO statements. This approach was originally proposed by Miroslav Benes as a workaround for identifying livepathes without depending on modinfo during the modpost stage. It was moved to this patch as the approach also shown to be useful while building symbols.klp. Signed-off-by: Joao Moreira <jmoreira@xxxxxxx> Signed-off-by: Joe Lawrence <joe.lawrence@xxxxxxxxxx> --- .gitignore | 1 + Documentation/dontdiff | 1 + Makefile | 24 ++++++++++++++++++++++-- 3 files changed, 24 insertions(+), 2 deletions(-) diff --git a/.gitignore b/.gitignore index 7afd412dadd2..50638a15a527 100644 --- a/.gitignore +++ b/.gitignore @@ -61,6 +61,7 @@ modules.order /vmlinux.symvers /vmlinux-gdb.py /vmlinuz +/symbols.klp /System.map /Module.markers /modules.builtin diff --git a/Documentation/dontdiff b/Documentation/dontdiff index 910b30a2a7d9..25c656fdd99f 100644 --- a/Documentation/dontdiff +++ b/Documentation/dontdiff @@ -76,6 +76,7 @@ Module.markers Module.symvers PENDING SCCS +symbols.klp System.map* TAGS aconf diff --git a/Makefile b/Makefile index 0fb4f94a6885..64ec4bc8172c 100644 --- a/Makefile +++ b/Makefile @@ -639,8 +639,13 @@ KBUILD_MODULES := KBUILD_BUILTIN := 1 # If we have only "make modules", don't compile built-in objects. +# When we're building livepatch modules, we need to consider the +# built-in objects during the descend as well, as built-in objects may +# hold symbols which are referenced from livepatches and are required by +# klp-convert post-processing tool for resolving these cases. + ifeq ($(MAKECMDGOALS),modules) - KBUILD_BUILTIN := + KBUILD_BUILTIN := $(if $(CONFIG_LIVEPATCH),1) endif # If we have "make <whatever> modules", compile modules @@ -1487,7 +1492,7 @@ MRPROPER_FILES += include/config include/generated \ arch/$(SRCARCH)/include/generated .tmp_objdiff \ debian snap tar-install \ .config .config.old .version \ - Module.symvers \ + Module.symvers symbols.klp \ certs/signing_key.pem \ certs/x509.genkey \ vmlinux-gdb.py \ @@ -1742,7 +1747,22 @@ PHONY += modules modules_install ifdef CONFIG_MODULES +quiet_cmd_klp_map = KLP symbols.klp + +define cmd_klp_map + $(shell echo "klp-convert-symbol-data.0.1" > $(objtree)/symbols.klp) \ + $(shell echo "*vmlinux" >> $(objtree)/symbols.klp) \ + $(shell nm -f posix $(objtree)/vmlinux | cut -d\ -f1 >> $(objtree)/symbols.klp) \ + $(foreach ko, $(sort $(shell cat modules.order)), \ + $(eval mod = $(patsubst %.ko,%.mod,$(ko))) \ + $(eval obj = $(patsubst %.ko,%.o,$(ko))) \ + $(if $(shell grep -o LIVEPATCH $(mod)),, \ + $(shell echo "*$(shell basename -s .ko $(ko))" >> $(objtree)/symbols.klp) \ + $(shell nm -f posix $(obj) | cut -d\ -f1 >> $(objtree)/symbols.klp))) +endef + modules: modules_check + $(if $(CONFIG_LIVEPATCH), $(call cmd,klp_map)) $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost PHONY += modules_check -- 2.26.3
