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2021-09-19kbuild: Fix comment typo in scripts/Makefile.modpostRamji Jiyani
Change comment "create one <module>.mod.c file pr. module" to "create one <module>.mod.c file per module" Signed-off-by: Ramji Jiyani <ramjiyani@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-09-03kbuild: Fix TRIM_UNUSED_KSYMS with LTO_CLANGSami Tolvanen
With CONFIG_LTO_CLANG, we currently link modules into native code just before modpost, which means with TRIM_UNUSED_KSYMS enabled, we still look at the LLVM bitcode in the .o files when generating the list of used symbols. As the bitcode doesn't yet have calls to compiler intrinsics and llvm-nm doesn't see function references that only exist in function-level inline assembly, we currently need a whitelist for TRIM_UNUSED_KSYMS to work with LTO. This change moves module LTO linking to happen earlier, and thus avoids the issue with LLVM bitcode and TRIM_UNUSED_KSYMS entirely, allowing us to also drop the whitelist from gen_autoksyms.sh. Link: https://github.com/ClangBuiltLinux/linux/issues/1369 Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Alexander Lobakin <alobakin@pm.me> Tested-by: Alexander Lobakin <alobakin@pm.me> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-04-25kbuild: fix false-positive modpost warning when all symbols are trimmedMasahiro Yamada
Nathan reports that the mips defconfig emits the following warning: WARNING: modpost: Symbol info of vmlinux is missing. Unresolved symbol check will be entirely skipped. This false-positive happens when CONFIG_TRIM_UNUSED_KSYMS is enabled, but no CONFIG option is set to 'm'. Commit a0590473c5e6 ("nfs: fix PNFS_FLEXFILE_LAYOUT Kconfig default") turned the last 'm' into 'y' for the mips defconfig, and uncovered this issue. In this case, the module feature itself is enabled, but we have no module to build. As a result, CONFIG_TRIM_UNUSED_KSYMS drops all the instances of EXPORT_SYMBOL. Then, modpost wrongly assumes vmlinux is missing because vmlinux.symvers is empty. (As another false-positive case, you can create a module that does not use any symbol of vmlinux). The current behavior is to entirely suppress the unresolved symbol warnings when vmlinux is missing just because there are too many. I found the origin of this code in the historical git tree. [1] If this is a matter of noisiness, I think modpost can display the first 10 warnings, and the number of suppressed warnings at the end. You will get a bit noisier logs when you run 'make modules' without vmlinux, but such warnings are better to show because you never know the resulting modules are actually loadable or not. This commit changes the following: - If any of input *.symver files is missing, pass -w option to let the module build keep going with warnings instead of errors. - If there are too many (10+) unresolved symbol warnings, show only the first 10, and also the number of suppressed warnings. [1]: https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/commit/?id=1cc0e0529569bf6a94f6d49770aa6d4b599d2c46 Reported-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-04-25kbuild: do not set -w for vmlinux.o modpostMasahiro Yamada
The -w option is meaningless for the first pass of modpost (vmlinux.o). We know there are unresolved symbols in vmlinux.o, hence we skip check_exports() and other checks when mod->is_vmlinux is set. See the following part in the for-loop. if (mod->is_vmlinux || mod->from_dump) continue; Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-04-25kbuild: generate Module.symvers only when vmlinux existsMasahiro Yamada
The external module build shows the following warning if Module.symvers is missing in the kernel tree. WARNING: Symbol version dump "Module.symvers" is missing. Modules may not have dependencies or modversions. I think this is an important heads-up because the resulting modules may not work as expected. This happens when you did not build the entire kernel tree, for example, you might have prepared the minimal setups for external modules by 'make defconfig && make modules_preapre'. A problem is that 'make modules' creates Module.symvers even without vmlinux. In this case, that warning is suppressed since Module.symvers already exists in spite of its incomplete content. The incomplete (i.e. invalid) Module.symvers should not be created. This commit changes the second pass of modpost to dump symbols into modules-only.symvers. The final Module.symvers is created by concatenating vmlinux.symvers and modules-only.symvers if both exist. Module.symvers is supposed to collect symbols from both vmlinux and modules. It might be a bit confusing, and I am not quite sure if it is an official interface, but presumably it is difficult to rename it because some tools (e.g. kmod) parse it. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-03-15kbuild: prefix $(srctree)/ to some included MakefilesMasahiro Yamada
VPATH is used in Kbuild to make pattern rules search for prerequisites in both $(objtree) and $(srctree). Some of *.c, *.S files are not real sources, but generated by tools such as flex, bison, perl. In contrast, I doubt the benefit of --include-dir=$(abs_srctree) because it is always clear which Makefiles are real sources, and which are not. So, my hope is to add $(srctree)/ prefix to all check-in Makefiles, then remove --include-dir=$(abs_srctree) flag in the future. I am touching only some Kbuild core parts for now. Treewide fixes will be needed to achieve this goal. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-01-14kbuild: lto: fix module versioningSami Tolvanen
With CONFIG_MODVERSIONS, version information is linked into each compilation unit that exports symbols. With LTO, we cannot use this method as all C code is compiled into LLVM bitcode instead. This change collects symbol versions into .symversions files and merges them in link-vmlinux.sh where they are all linked into vmlinux.o at the same time. Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20201211184633.3213045-4-samitolvanen@google.com
2021-01-14kbuild: add support for Clang LTOSami Tolvanen
This change adds build system support for Clang's Link Time Optimization (LTO). With -flto, instead of ELF object files, Clang produces LLVM bitcode, which is compiled into native code at link time, allowing the final binary to be optimized globally. For more details, see: https://llvm.org/docs/LinkTimeOptimization.html The Kconfig option CONFIG_LTO_CLANG is implemented as a choice, which defaults to LTO being disabled. To use LTO, the architecture must select ARCH_SUPPORTS_LTO_CLANG and support: - compiling with Clang, - compiling all assembly code with Clang's integrated assembler, - and linking with LLD. While using CONFIG_LTO_CLANG_FULL results in the best runtime performance, the compilation is not scalable in time or memory. CONFIG_LTO_CLANG_THIN enables ThinLTO, which allows parallel optimization and faster incremental builds. ThinLTO is used by default if the architecture also selects ARCH_SUPPORTS_LTO_CLANG_THIN: https://clang.llvm.org/docs/ThinLTO.html To enable LTO, LLVM tools must be used to handle bitcode files, by passing LLVM=1 and LLVM_IAS=1 options to make: $ make LLVM=1 LLVM_IAS=1 defconfig $ scripts/config -e LTO_CLANG_THIN $ make LLVM=1 LLVM_IAS=1 To prepare for LTO support with other compilers, common parts are gated behind the CONFIG_LTO option, and LTO can be disabled for specific files by filtering out CC_FLAGS_LTO. Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20201211184633.3213045-3-samitolvanen@google.com
2020-08-02kbuild: remove redundant FORCE definition in scripts/Makefile.modpostMasahiro Yamada
The same code exists a few lines above. Fixes: 436b2ac603d5 ("modpost: invoke modpost only when input files are updated") Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-06-06modpost: move -d option in scripts/Makefile.modpostMasahiro Yamada
Collect options for modules into a single place. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-06-06modpost: remove -s optionMasahiro Yamada
The -s option was added by commit 8d8d8289df65 ("kbuild: do not do section mismatch checks on vmlinux in 2nd pass"). Now that the second pass does not parse vmlinux, this option is unneeded. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-06-06modpost: show warning if any of symbol dump files is missingMasahiro Yamada
If modpost fails to load a symbol dump file, it cannot check unresolved symbols, hence module dependency will not be added. Nor CRCs can be added. Currently, external module builds check only $(objtree)/Module.symvers, but it should check files specified by KBUILD_EXTRA_SYMBOLS as well. Move the warning message from the top Makefile to scripts/Makefile.modpost and print the warning if any dump file is missing. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-06-06modpost: invoke modpost only when input files are updatedMasahiro Yamada
Currently, the second pass of modpost is always invoked when you run 'make' or 'make modules' even if none of modules is changed. Use if_changed to invoke it only when it is necessary. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-06-06modpost: generate vmlinux.symvers and reuse it for the second modpostMasahiro Yamada
The full build runs modpost twice, first for vmlinux.o and second for modules. The first pass dumps all the vmlinux symbols into Module.symvers, but the second pass parses vmlinux again instead of reusing the dump file, presumably because it needs to avoid accumulating stale symbols. Loading symbol info from a dump file is faster than parsing an ELF object. Besides, modpost deals with various issues to parse vmlinux in the second pass. A solution is to make the first pass dumps symbols into a separate file, vmlinux.symvers. The second pass reads it, and parses module .o files. The merged symbol information is dumped into Module.symvers in the same way as before. This makes further modpost cleanups possible. Also, it fixes the problem of 'make vmlinux', which previously overwrote Module.symvers, throwing away module symbols. I slightly touched scripts/link-vmlinux.sh so that vmlinux is re-linked when you cross this commit. Otherwise, vmlinux.symvers would not be generated. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-06-06modpost: refactor -i option calculationMasahiro Yamada
Prepare to use -i for in-tree modpost as well. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-06-06modpost: print symbol dump file as the build target in short logMasahiro Yamada
The symbol dump *.symvers is the output of modpost. Print it in the short log. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-06-06modpost: re-add -e to set external_module flagMasahiro Yamada
Previously, the -i option had two functions; load a symbol dump file, and set the external_module flag. I want to assign a dedicate option for each of them. Going forward, the -i is used to load a symbol dump file, and the -e to set the external_module flag. With this, we will be able to use -i for loading in-kernel symbols. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-06-06modpost: allow to pass -i option multiple times to remove -e optionMasahiro Yamada
Now that there is no difference between -i and -e, they can be unified. Make modpost accept the -i option multiple times, then remove -e. I will reuse -e for a different purpose. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-06-03modpost: pass -N option only for modules modpostMasahiro Yamada
The built-in only code is not required to have MODULE_IMPORT_NS() to use symbols. So, the namespace is not checked for vmlinux(.o). Do not pass the meaningless -N option to the first pass of modpost. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-06-03modpost: move -T option close to the modpost commandMasahiro Yamada
The '-T -' option reads the file list from stdin. It is clearer to put it close to the piped command. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-06-03modpost: fix -i (--ignore-errors) MAKEFLAGS detectionMasahiro Yamada
$(filter -i,$(MAKEFLAGS)) works only in limited use-cases. The representation of $(MAKEFLAGS) depends on various factors: - GNU Make version (version 3.8x or version 4.x) - The presence of other flags like -j In my experiments, $(MAKEFLAGS) is expanded as follows: * GNU Make 3.8x: * without -j option: --no-print-directory -Rri * with -j option: --no-print-directory -Rr --jobserver-fds=3,4 -j -i * GNU Make 4.x: * without -j option: irR --no-print-directory * with -j option: irR -j --jobserver-fds=3,4 --no-print-directory For GNU Make 4.x, the flags are grouped as 'irR', which does not work. For the single thread build with GNU Make 3.8x, the flags are grouped as '-Rri', which does not work either. To make it work for all cases, do likewise as commit 6f0fa58e4596 ("kbuild: simplify silent build (-s) detection"). BTW, since commit ff9b45c55b26 ("kbuild: modpost: read modules.order instead of $(MODVERDIR)/*.mod"), you also need to pass -k option to build final *.ko files. 'make -i -k' ignores compile errors in modules, and build as many remaining *.ko as possible. Please note this feature is kind of dangerous if other modules depend on the broken module because the generated modules will lack the correct module dependency or CRC. Honestly, I am not a big fan of it, but I am keeping this feature. Fixes: eed380f3f593 ("modpost: Optionally ignore secondary errors seen if a single module build fails") Cc: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-29kbuild: disallow multi-word in M= or KBUILD_EXTMODMasahiro Yamada
$(firstword ...) in scripts/Makefile.modpost was added by commit 3f3fd3c05585 ("[PATCH] kbuild: allow multi-word $M in Makefile.modpost") to build multiple external module directories. It was a solution to resolve symbol dependencies when an external module depends on another external module. Commit 0d96fb20b7ed ("kbuild: Add new Kbuild variable KBUILD_EXTRA_SYMBOLS") introduced another solution by passing symbol info via KBUILD_EXTRA_SYMBOLS, then broke the multi-word M= support. include $(if $(wildcard $(KBUILD_EXTMOD)/Kbuild), \ $(KBUILD_EXTMOD)/Kbuild, $(KBUILD_EXTMOD)/Makefile) ... does not work if KBUILD_EXTMOD contains multiple words. This feature has been broken for more than a decade. Remove the bitrotten code, and stop parsing if M or KBUILD_EXTMOD contains multiple words. As Documentation/kbuild/modules.rst explains, if your module depends on another one, there are two solutions: - add a common top-level Kbuild file - use KBUILD_EXTRA_SYMBOLS Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-03-13modpost: return error if module is missing ns imports and ↵Jessica Yu
MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS=n Currently when CONFIG_MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS=n, modpost only warns when a module is missing namespace imports. Under this configuration, such a module cannot be loaded into the kernel anyway, as the module loader would reject it. We might as well return a build error when a module is missing namespace imports under CONFIG_MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS=n, so that the build warning does not go ignored/unnoticed. Signed-off-by: Jessica Yu <jeyu@kernel.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-01-16kbuild: remove 'Building modules, stage 2.' logMasahiro Yamada
This log is displayed every time modules are built, but it is not so important. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2019-11-11scripts/nsdeps: support nsdeps for external module buildsMasahiro Yamada
scripts/nsdeps is written to take care of only in-tree modules. Perhaps, this is not a bug, but just a design. At least, Documentation/core-api/symbol-namespaces.rst focuses on in-tree modules. Having said that, some people already tried nsdeps for external modules. So, it would be nice to support it. Reported-by: Steve French <smfrench@gmail.com> Reported-by: Jessica Yu <jeyu@kernel.org> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Tested-by: Jessica Yu <jeyu@kernel.org> Acked-by: Jessica Yu <jeyu@kernel.org> Reviewed-by: Matthias Maennich <maennich@google.com> Tested-by: Matthias Maennich <maennich@google.com>
2019-11-11modpost: dump missing namespaces into a single modules.nsdeps fileMasahiro Yamada
The modpost, with the -d option given, generates per-module .ns_deps files. Kbuild generates per-module .mod files to carry module information. This is convenient because Make handles multiple jobs in parallel when the -j option is given. On the other hand, the modpost always runs as a single thread. I do not see a strong reason to produce separate .ns_deps files. This commit changes the modpost to generate just one file, modules.nsdeps, each line of which has the following format: <module_name>: <list of missing namespaces> Please note it contains *missing* namespaces instead of required ones. So, modules.nsdeps is empty if the namespace dependency is all good. This will work more efficiently because spatch will no longer process already imported namespaces. I removed the '(if needed)' from the nsdeps log since spatch is invoked only when needed. This also solves the stale .ns_deps problem reported by Jessica Yu: https://lkml.org/lkml/2019/10/28/467 Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Tested-by: Jessica Yu <jeyu@kernel.org> Acked-by: Jessica Yu <jeyu@kernel.org> Reviewed-by: Matthias Maennich <maennich@google.com> Tested-by: Matthias Maennich <maennich@google.com>
2019-11-11modpost: do not invoke extra modpost for nsdepsMasahiro Yamada
'make nsdeps' invokes the modpost three times at most; before linking vmlinux, before building modules, and finally for generating .ns_deps files. Running the modpost again and again is not efficient. The last two can be unified. When the -d option is given, the modpost still does the usual job, and in addition, generates .ns_deps files. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Tested-by: Matthias Maennich <maennich@google.com> Reviewed-by: Matthias Maennich <maennich@google.com>
2019-11-11kbuild: do not read $(KBUILD_EXTMOD)/Module.symversMasahiro Yamada
Since commit 040fcc819a2e ("kbuild: improved modversioning support for external modules"), the external module build reads Module.symvers in the directory of the module itself, then dumps symbols back into it. It accumulates stale symbols in the file when you build an external module incrementally. The idea behind it was, as the commit log explained, you can copy Modules.symvers from one module to another when you need to pass symbol information between two modules. However, the manual copy of the file sounds questionable to me, and containing stale symbols is a downside. Some time later, commit 0d96fb20b7ed ("kbuild: Add new Kbuild variable KBUILD_EXTRA_SYMBOLS") introduced a saner approach. So, this commit removes the former one. Going forward, the external module build dumps symbols into Module.symvers to be carried via KBUILD_EXTRA_SYMBOLS, but never reads it automatically. With the -I option removed, there is no one to set the external_module flag unless KBUILD_EXTRA_SYMBOLS is passed. Now the -i option does it instead. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2019-11-11modpost: do not parse vmlinux for external module buildsMasahiro Yamada
When building external modules, $(objtree)/Module.symvers is scanned for symbol information of vmlinux and in-tree modules. Additionally, vmlinux is parsed if it exists in $(objtree)/. This is totally redundant since all the necessary information is contained in $(objtree)/Module.symvers. Do not parse vmlinux at all for external module builds. This makes sense because vmlinux is deleted by 'make clean'. 'make clean' leaves all the build artifacts for building external modules. vmlinux is unneeded for that. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2019-11-11kbuild: update comments in scripts/Makefile.modpostMasahiro Yamada
The comment line "When building external modules ..." explains the same thing as "Include the module's Makefile ..." a few lines below. The comment "they may be used when building the .mod.c file" is no longer true; .mod.c file is compiled in scripts/Makefile.modfinal since commit 9b9a3f20cbe0 ("kbuild: split final module linking out into Makefile.modfinal"). I still keep the code in case $(obj) or $(src) is used in the external module Makefile. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2019-09-22Merge tag 'modules-for-v5.4' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux Pull modules updates from Jessica Yu: "The main bulk of this pull request introduces a new exported symbol namespaces feature. The number of exported symbols is increasingly growing with each release (we're at about 31k exports as of 5.3-rc7) and we currently have no way of visualizing how these symbols are "clustered" or making sense of this huge export surface. Namespacing exported symbols allows kernel developers to more explicitly partition and categorize exported symbols, as well as more easily limiting the availability of namespaced symbols to other parts of the kernel. For starters, we have introduced the USB_STORAGE namespace to demonstrate the API's usage. I have briefly summarized the feature and its main motivations in the tag below. Summary: - Introduce exported symbol namespaces. This new feature allows subsystem maintainers to partition and categorize their exported symbols into explicit namespaces. Module authors are now required to import the namespaces they need. Some of the main motivations of this feature include: allowing kernel developers to better manage the export surface, allow subsystem maintainers to explicitly state that usage of some exported symbols should only be limited to certain users (think: inter-module or inter-driver symbols, debugging symbols, etc), as well as more easily limiting the availability of namespaced symbols to other parts of the kernel. With the module import requirement, it is also easier to spot the misuse of exported symbols during patch review. Two new macros are introduced: EXPORT_SYMBOL_NS() and EXPORT_SYMBOL_NS_GPL(). The API is thoroughly documented in Documentation/kbuild/namespaces.rst. - Some small code and kbuild cleanups here and there" * tag 'modules-for-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux: module: Remove leftover '#undef' from export header module: remove unneeded casts in cmp_name() module: move CONFIG_UNUSED_SYMBOLS to the sub-menu of MODULES module: remove redundant 'depends on MODULES' module: Fix link failure due to invalid relocation on namespace offset usb-storage: export symbols in USB_STORAGE namespace usb-storage: remove single-use define for debugging docs: Add documentation for Symbol Namespaces scripts: Coccinelle script for namespace dependencies. modpost: add support for generating namespace dependencies export: allow definition default namespaces in Makefiles or sources module: add config option MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS modpost: add support for symbol namespaces module: add support for symbol namespaces. export: explicitly align struct kernel_symbol module: support reading multiple values per modinfo tag
2019-09-10scripts: Coccinelle script for namespace dependencies.Matthias Maennich
A script that uses the '<module>.ns_deps' files generated by modpost to automatically add the required symbol namespace dependencies to each module. Usage: 1) Move some symbols to a namespace with EXPORT_SYMBOL_NS() or define DEFAULT_SYMBOL_NAMESPACE 2) Run 'make' (or 'make modules') and get warnings about modules not importing that namespace. 3) Run 'make nsdeps' to automatically add required import statements to said modules. This makes it easer for subsystem maintainers to introduce and maintain symbol namespaces into their codebase. Co-developed-by: Martijn Coenen <maco@android.com> Signed-off-by: Martijn Coenen <maco@android.com> Acked-by: Julia Lawall <julia.lawall@lip6.fr> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Matthias Maennich <maennich@google.com> Signed-off-by: Jessica Yu <jeyu@kernel.org>
2019-08-22kbuild: split final module linking out into Makefile.modfinalMasahiro Yamada
I think splitting the modpost and linking modules into separate Makefiles will be useful especially when more complex build steps come in. The main motivation of this commit is to integrate the proposed klp-convert feature cleanly. I moved the logging 'Building modules, stage 2.' to Makefile.modpost to avoid the code duplication although I do not know whether or not this message is needed in the first place. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2019-08-21kbuild: rebuild modules when module linker scripts are updatedMasahiro Yamada
Currently, the timestamp of module linker scripts are not checked. Add them to the dependency of modules so they are correctly rebuilt. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2019-08-14kbuild: add [M] marker for build log of *.mod.oMasahiro Yamada
This builds module objects, so [M] makes sense. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2019-08-14Kbuild: Handle PREEMPT_RT for version string and magicThomas Gleixner
Update the build scripts and the version magic to reflect when CONFIG_PREEMPT_RT is enabled in the same way as CONFIG_PREEMPT is treated. The resulting version strings: Linux m 5.3.0-rc1+ #100 SMP Fri Jul 26 ... Linux m 5.3.0-rc1+ #101 SMP PREEMPT Fri Jul 26 ... Linux m 5.3.0-rc1+ #102 SMP PREEMPT_RT Fri Jul 26 ... The module vermagic: 5.3.0-rc1+ SMP mod_unload modversions 5.3.0-rc1+ SMP preempt mod_unload modversions 5.3.0-rc1+ SMP preempt_rt mod_unload modversions Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2019-08-10kbuild: revive single target %.koMasahiro Yamada
I removed the single target %.ko in commit ff9b45c55b26 ("kbuild: modpost: read modules.order instead of $(MODVERDIR)/*.mod") because the modpost stage does not work reliably. For instance, the module dependency, modversion, etc. do not work if we lack symbol information from the other modules. Yet, some people still want to build only one module in their interest, and it may be still useful if it is used within those limitations. Fixes: ff9b45c55b26 ("kbuild: modpost: read modules.order instead of $(MODVERDIR)/*.mod") Reported-by: Don Brace <don.brace@microsemi.com> Reported-by: Arend Van Spriel <arend.vanspriel@broadcom.com> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2019-08-01kbuild: modpost: do not parse unnecessary rules for vmlinux modpostMasahiro Yamada
Since commit ff9b45c55b26 ("kbuild: modpost: read modules.order instead of $(MODVERDIR)/*.mod"), 'make vmlinux' emits a warning, like this: $ make defconfig vmlinux [ snip ] LD vmlinux.o cat: modules.order: No such file or directory MODPOST vmlinux.o MODINFO modules.builtin.modinfo KSYM .tmp_kallsyms1.o KSYM .tmp_kallsyms2.o LD vmlinux SORTEX vmlinux SYSMAP System.map When building only vmlinux, KBUILD_MODULES is not set. Hence, the modules.order is not generated. For the vmlinux modpost, it is not necessary at all. Separate scripts/Makefile.modpost for the vmlinux/modules stages. This works more efficiently because the vmlinux modpost does not need to include .*.cmd files. Fixes: ff9b45c55b26 ("kbuild: modpost: read modules.order instead of $(MODVERDIR)/*.mod") Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2019-08-01kbuild: modpost: remove unnecessary dependency for __modpostMasahiro Yamada
__modpost is a phony target. The dependency on FORCE is pointless. All the objects have been built in the previous stage, so the dependency on the objects are not necessary either. Count the number of modules in a more straightforward way. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2019-08-01kbuild: modpost: handle KBUILD_EXTRA_SYMBOLS only for external modulesMasahiro Yamada
KBUILD_EXTRA_SYMBOLS makes sense only when building external modules. Moreover, the modpost sets 'external_module' if the -e option is given. I replaced $(patsubst %, -e %,...) with simpler $(addprefix -e,...) while I was here. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2019-08-01kbuild: modpost: include .*.cmd files only when targets existMasahiro Yamada
If a build rule fails, the .DELETE_ON_ERROR special target removes the target, but does nothing for the .*.cmd file, which might be corrupted. So, .*.cmd files should be included only when the corresponding targets exist. Commit 392885ee82d3 ("kbuild: let fixdep directly write to .*.cmd files") missed to fix up this file. Fixes: 392885ee82d3 ("kbuild: let fixdep directly write to .*.cmd") Cc: <stable@vger.kernel.org> # v5.0+ Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2019-07-18kbuild: create *.mod with full directory path and remove MODVERDIRMasahiro Yamada
While descending directories, Kbuild produces objects for modules, but do not link final *.ko files; it is done in the modpost. To keep track of modules, Kbuild creates a *.mod file in $(MODVERDIR) for every module it is building. Some post-processing steps read the necessary information from *.mod files. This avoids descending into directories again. This mechanism was introduced in 2003 or so. Later, commit 551559e13af1 ("kbuild: implement modules.order") added modules.order. So, we can simply read it out to know all the modules with directory paths. This is easier than parsing the first line of *.mod files. $(MODVERDIR) has a flat directory structure, that is, *.mod files are named only with base names. This is based on the assumption that the module name is unique across the tree. This assumption is really fragile. Stephen Rothwell reported a race condition caused by a module name conflict: https://lkml.org/lkml/2019/5/13/991 In parallel building, two different threads could write to the same $(MODVERDIR)/*.mod simultaneously. Non-unique module names are the source of all kind of troubles, hence commit 3a48a91901c5 ("kbuild: check uniqueness of module names") introduced a new checker script. However, it is still fragile in the build system point of view because this race happens before scripts/modules-check.sh is invoked. If it happens again, the modpost will emit unclear error messages. To fix this issue completely, create *.mod with full directory path so that two threads never attempt to write to the same file. $(MODVERDIR) is no longer needed. Since modules with directory paths are listed in modules.order, Kbuild is still able to find *.mod files without additional descending. I also killed cmd_secanalysis; scripts/mod/sumversion.c computes MD4 hash for modules with MODULE_VERSION(). When CONFIG_DEBUG_SECTION_MISMATCH=y, it occurs not only in the modpost stage, but also during directory descending, where sumversion.c may parse stale *.mod files. It would emit 'No such file or directory' warning when an object consisting a module is renamed, or when a single-obj module is turned into a multi-obj module or vice versa. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Acked-by: Nicolas Pitre <nico@fluxnic.net>
2019-07-18kbuild: modpost: read modules.order instead of $(MODVERDIR)/*.modMasahiro Yamada
Towards the goal of removing MODVERDIR, read out modules.order to get the list of modules to be processed. This is simpler than parsing *.mod files in $(MODVERDIR). For external modules, $(KBUILD_EXTMOD)/modules.order should be read. I removed the single target %.ko from the top Makefile. To make sure modpost works correctly, vmlinux and the other modules must be built. You cannot build a particular .ko file alone. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2019-04-11modpost: make KBUILD_MODPOST_WARN also configurable for external modulesWiebe, Wladislav (Nokia - DE/Ulm)
Commit ea837f1c0503 ("kbuild: make modpost processing configurable") was intended to give KBUILD_MODPOST_WARN flexibility to be configurable. Right now KBUILD_MODPOST_WARN gets just ignored when KBUILD_EXTMOD is set which happens per default when building modules out of the tree. This change gives the opportunity to define module build behaving also in case of out of tree builds and default will become exit on error. Errors which can be detected by the build should be trapped out of the box there, unless somebody wants to notice broken stuff later at runtime. As this patch changes the default behaving from warning to error, users can consider to fix it for external module builds by: - providing module symbol table via KBUILD_EXTRA_SYMBOLS for modules which are dependent - OR getting old behaving back by passing KBUILD_MODPOST_WARN to the build Signed-off-by: Wladislav Wiebe <wladislav.wiebe@nokia.com> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2019-03-14modpost: always show verbose warning for section mismatchMasahiro Yamada
Unless CONFIG_DEBUG_SECTION_MISMATCH is enabled, modpost only shows the number of section mismatches. If you want to know the symbols causing the issue, you need to rebuild with CONFIG_DEBUG_SECTION_MISMATCH. It is tedious. I think it is fine to show annoying warning when a new section mismatch comes in. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2019-01-28kbuild: add real-prereqs shorthand for $(filter-out FORCE,$^)Masahiro Yamada
In Kbuild, if_changed and friends must have FORCE as a prerequisite. Hence, $(filter-out FORCE,$^) or $(filter-out $(PHONY),$^) is a common idiom to get the names of all the prerequisites except phony targets. Add real-prereqs as a shorthand. Note: We cannot replace $(filter %.o,$^) in cmd_link_multi-m because $^ may include auto-generated dependencies from the .*.cmd file when a single object module is changed into a multi object module. Refer to commit 69ea912fda74 ("kbuild: remove unneeded link_multi_deps"). I added some comment to avoid accidental breakage. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Acked-by: Rob Herring <robh@kernel.org>
2018-08-24kbuild: rename LDFLAGS to KBUILD_LDFLAGSMasahiro Yamada
Commit a0f97e06a43c ("kbuild: enable 'make CFLAGS=...' to add additional options to CC") renamed CFLAGS to KBUILD_CFLAGS. Commit 222d394d30e7 ("kbuild: enable 'make AFLAGS=...' to add additional options to AS") renamed AFLAGS to KBUILD_AFLAGS. Commit 06c5040cdb13 ("kbuild: enable 'make CPPFLAGS=...' to add additional options to CPP") renamed CPPFLAGS to KBUILD_CPPFLAGS. For some reason, LDFLAGS was not renamed. Using a well-known variable like LDFLAGS may result in accidental override of the variable. Kbuild generally uses KBUILD_ prefixed variables for the internally appended options, so here is one more conversion to sanitize the naming convention. I did not touch Makefiles under tools/ since the tools build system is a different world. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
2018-07-06kbuild: remove duplicated comments about PHONYMasahiro Yamada
The comment is the same as in the top-level Makefile. Also, the comments contain typos: - the .PHONY variable -> the PHONY variable - se we can ... -> so we can ... Instead of fixing the typos, just remove the duplicated comments. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2017-11-17Merge tag 'kbuild-v4.15' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild Pull Kbuild updates from Masahiro Yamada: "One of the most remarkable improvements in this cycle is, Kbuild is now able to cache the result of shell commands. Some variables are expensive to compute, for example, $(call cc-option,...) invokes the compiler. It is not efficient to redo this computation every time, even when we are not actually building anything. Kbuild creates a hidden file ".cache.mk" that contains invoked shell commands and their results. The speed-up should be noticeable. Summary: - Fix arch build issues (hexagon, sh) - Clean up various Makefiles and scripts - Fix wrong usage of {CFLAGS,LDFLAGS}_MODULE in arch Makefiles - Cache variables that are expensive to compute - Improve cc-ldopton and ld-option for Clang - Optimize output directory creation" * tag 'kbuild-v4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (30 commits) kbuild: move coccicheck help from scripts/Makefile.help to top Makefile sh: decompressor: add shipped files to .gitignore frv: .gitignore: ignore vmlinux.lds selinux: remove unnecessary assignment to subdir- kbuild: specify FORCE in Makefile.headersinst as .PHONY target kbuild: remove redundant mkdir from ./Kbuild kbuild: optimize object directory creation for incremental build kbuild: create object directories simpler and faster kbuild: filter-out PHONY targets from "targets" kbuild: remove redundant $(wildcard ...) for cmd_files calculation kbuild: create directory for make cache only when necessary sh: select KBUILD_DEFCONFIG depending on ARCH kbuild: fix linker feature test macros when cross compiling with Clang kbuild: shrink .cache.mk when it exceeds 1000 lines kbuild: do not call cc-option before KBUILD_CFLAGS initialization kbuild: Cache a few more calls to the compiler kbuild: Add a cache for generated variables kbuild: add forward declaration of default target to Makefile.asm-generic kbuild: remove KBUILD_SUBDIR_ASFLAGS and KBUILD_SUBDIR_CCFLAGS hexagon/kbuild: replace CFLAGS_MODULE with KBUILD_CFLAGS_MODULE ...
2017-11-16kbuild: remove redundant $(wildcard ...) for cmd_files calculationMasahiro Yamada
I do not see any reason why $(wildcard ...) needs to be called twice for computing cmd_files. Remove the first one. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>