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* kbuild: rename KBUILD_ENABLE_EXTRA_GCC_CHECKS to KBUILD_EXTRA_WARNMasahiro Yamada2019-09-061-1/+1
| | | | | | | | | | | | | | | | | | KBUILD_ENABLE_EXTRA_GCC_CHECKS started as a switch to add extra warning options for GCC, but now it is a historical misnomer since we use it also for Clang, DTC, and even kernel-doc. Rename it to more sensible, shorter KBUILD_EXTRA_WARN. For the backward compatibility, KBUILD_ENABLE_EXTRA_GCC_CHECKS is still supported (but not advertised in the documentation). I also fixed up 'make help', and updated the documentation. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com>
* kbuild: move modkern_{c,a}flags to Makefile.lib from Makefile.buildMasahiro Yamada2019-08-211-13/+0
| | | | | | | | | Makefile.lib is included by Makefile.modfinal as well as Makefile.build. Move modkern_cflags to Makefile.lib in order to simplify cmd_cc_o_c in Makefile.modfinal. Move modkern_cflags as well for consistency. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
* kbuild: add CONFIG_ASM_MODVERSIONSMasahiro Yamada2019-08-211-6/+1
| | | | | | | | | | | | | Add CONFIG_ASM_MODVERSIONS. This allows to remove one if-conditional nesting in scripts/Makefile.build. scripts/Makefile.build is run every time Kbuild descends into a sub-directory. So, I want to avoid $(wildcard ...) evaluation where possible although computing $(wildcard ...) is so cheap that it may not make measurable performance difference. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
* kbuild: make single targets work more correctlyMasahiro Yamada2019-08-211-6/+39
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, the single target build directly descends into the directory of the target. For example, $ make foo/bar/baz.o ... directly descends into foo/bar/. On the other hand, the normal build usually descends one directory at a time, i.e. descends into foo/, and then foo/bar/. This difference causes some problems. [1] miss subdir-asflags-y, subdir-ccflags-y in upper Makefiles The options in subdir-{as,cc}flags-y take effect in the current and its sub-directories. In other words, they are inherited downward. In the example above, the single target will miss subdir-{as,cc}flags-y if they are defined in foo/Makefile. [2] could be built in a different directory As Documentation/kbuild/modules.rst section 4.3 says, Kbuild can handle files that are spread over several sub-directories. The build rule of foo/bar/baz.o may not necessarily be specified in foo/bar/Makefile. It might be specifies in foo/Makefile as follows: [foo/Makefile] obj-y := bar/baz.o This often happens when a module is so big that its source files are divided into sub-directories. In this case, there is no Makefile in the foo/bar/ directory, yet the single target descends into foo/bar/, then fails due to the missing Makefile. You can still do 'make foo/bar/' for partial building, but cannot do 'make foo/bar/baz.s'. I believe the single target '%.s' is a useful feature for inspecting the compiler output. Some modules work around this issue by putting an empty Makefile in every sub-directory. This commit fixes those problems by making the single target build descend in the same way as the normal build does. Another change is the single target build will observe the CONFIG options. Previously, it allowed users to build the foo.o even when the corresponding CONFIG_FOO is disabled: obj-$(CONFIG_FOO) += foo.o In the new behavior, the single target build will just fail and show "No rule to make target ..." (or "Nothing to be done for ..." if the stale object already exists, but cannot be updated). The disadvantage of this commit is the build speed. Now that the single target build visits every directory and parses lots of Makefiles, it is slower than before. (But, I hope it will not be too slow.) Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
* kbuild: fix modkern_aflags implementationMasahiro Yamada2019-08-141-4/+3
| | | | | | | | | | | | | | | For the single target building %.symtypes from %.S, $(a_flags) is expanded into the _KERNEL flags even if the object is a part of a module. $(real-obj-m:.o=.symtypes): modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE) ... would fix the issue, but it is not nice to duplicate similar code for every suffix. Implement modkern_aflags in the same way as modkern_cflags. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
* kbuild: refactor part-of-module moreMasahiro Yamada2019-08-141-2/+1
| | | | | | Make it even shorter. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
* kbuild: use $(basename ...) for cmd_asn1_compilerMasahiro Yamada2019-08-131-2/+2
| | | | | | | | | | | | | | | | | | | | | | $(basename ...) trims the last suffix. Using it is more intuitive in my opinion. This pattern rule makes %.asn1.c and %.asn1.h at the same time. Previously, the short log showed only either of them, depending on the target file in question. To clarify that two files are being generated by the single recipe, I changed the log as follows: Before: ASN.1 crypto/asymmetric_keys/x509.asn1.c After: ASN.1 crypto/asymmetric_keys/x509.asn1.[ch] Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
* kbuild: show hint if subdir-y/m is used to visit module MakefileMasahiro Yamada2019-08-091-0/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since commit ff9b45c55b26 ("kbuild: modpost: read modules.order instead of $(MODVERDIR)/*.mod"), a module is no longer built in the following pattern: [Makefile] subdir-y := some-module [some-module/Makefile] obj-m := some-module.o You cannot write Makefile this way in upstream because modules.order is not correctly generated. subdir-y is used to descend to a sub-directory that builds tools, device trees, etc. For external modules, the modules order does not matter. So, the Makefile above was known to work. I believe the Makefile should be re-written as follows: [Makefile] obj-m := some-module/ [some-module/Makefile] obj-m := some-module.o However, people will have no idea if their Makefile suddenly stops working. In fact, I received questions from multiple people. Show a warning for a while if obj-m is specified in a Makefile visited by subdir-y or subdir-m. I touched the %/ rule to avoid false-positive warnings for the single target. Cc: Jan Kiszka <jan.kiszka@siemens.com> Cc: Tom Stonecypher <thomas.edwardx.stonecypher@intel.com> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Tested-by: Jan Kiszka <jan.kiszka@siemens.com>
* kbuild: generate modules.order only in directories visited by obj-y/mMasahiro Yamada2019-08-091-1/+2
| | | | | | | | | | The modules.order files in directories visited by the chain of obj-y or obj-m are merged to the upper-level ones, and become parts of the top-level modules.order. On the other hand, there is no need to generate modules.order in directories visited by subdir-y or subdir-m since they would become orphan anyway. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
* kbuild: fix false-positive need-builtin calculationMasahiro Yamada2019-08-091-1/+2
| | | | | | | | | | | | The current implementation of need-builtin is false-positive, for example, in the following Makefile: obj-m := foo/ obj-y := foo/bar/ ..., where foo/built-in.a is not required. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
* kbuild: split out *.mod out of {single,multi}-used-m rulesMasahiro Yamada2019-07-171-9/+13
| | | | | | | | | | | | Currently, *.mod is created as a side-effect of obj-m. Split out *.mod as a dedicated build rule, which allows to unify the %.c -> %.o rule, and remove the single-used-m rule. This also makes the incremental build of allmodconfig faster because it saves $(NM) invocation when there is no change in the module. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
* kbuild: remove the first line of *.mod filesMasahiro Yamada2019-07-171-2/+2
| | | | | | | | | | | | | | | | The current format of *.mod is like this: line 1: directory path to the .ko file line 2: a list of objects linked into this module line 3: unresolved symbols (only when CONFIG_TRIM_UNUSED_KSYMS=y) Now that *.mod and *.ko are created in the same directory, the line 1 provides no valuable information. It can be derived by replacing the extension .mod with .ko. In fact, nobody uses the first line any more. Cut down the first line. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
* kbuild: create *.mod with full directory path and remove MODVERDIRMasahiro Yamada2019-07-171-12/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* kbuild: remove duplication from modules.order in sub-directoriesMasahiro Yamada2019-07-171-6/+3
| | | | | | | | | | | | | Currently, only the top-level modules.order drops duplicated entries. The modules.order files in sub-directories potentially contain duplication. To list out the paths of all modules, I want to use modules.order instead of parsing *.mod files in $(MODVERDIR). To achieve this, I want to rip off duplication from modules.order of external modules too. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
* kbuild: get rid of kernel/ prefix from in-tree modules.{order,builtin}Masahiro Yamada2019-07-171-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | Removing the 'kernel/' prefix will make our life easier because we can simply do 'cat modules.order' to get all built modules with full paths. Currently, we parse the first line of '*.mod' files in $(MODVERDIR). Since we have duplicated functionality here, I plan to remove MODVERDIR entirely. In fact, modules.order is generated also for external modules in a broken format. It adds the 'kernel/' prefix to the absolute path of the module, like this: kernel//path/to/your/external/module/foo.ko This is fine for now since modules.order is not used for external modules. However, I want to sanitize the format everywhere towards the goal of removing MODVERDIR. We cannot change the format of installed module.{order,builtin}. So, 'make modules_install' will add the 'kernel/' prefix while copying them to $(MODLIB)/. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
* kbuild: do not create empty modules.order in the prepare stageMasahiro Yamada2019-07-171-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, $(objtree)/modules.order is touched in two places. In the 'prepare0' rule, scripts/Makefile.build creates an empty modules.order while processing 'obj=.' In the 'modules' rule, the top-level Makefile overwrites it with the correct list of modules. While this might be a good side-effect that modules.order is made empty every time (probably this is not intended functionality), I personally do not like this behavior. Create modules.order only when it is sensible to do so. This avoids creating the following pointless files: scripts/basic/modules.order scripts/dtc/modules.order scripts/gcc-plugins/modules.order scripts/genksyms/modules.order scripts/mod/modules.order scripts/modules.order scripts/selinux/genheaders/modules.order scripts/selinux/mdp/modules.order scripts/selinux/modules.order Going forward, $(objtree)/modules.order lists the modules that was built in the last successful build. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
* kbuild: compile-test headers listed in header-test-m as wellMasahiro Yamada2019-07-171-1/+1
| | | | | | | | | | It will be useful to control the header-test by a tristate option. If CONFIG_FOO is a tristate option, you can write like this: header-test-$(CONFIG_FOO) += foo.h Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
* kbuild: replace KBUILD_SRCTREE with boolean building_out_of_srctreeMasahiro Yamada2019-07-101-1/+1
| | | | | | | | | | | | | | Commit 25b146c5b8ce ("kbuild: allow Kbuild to start from any directory") deprecated KBUILD_SRCTREE. It is only used in tools/testing/selftest/ to distinguish out-of-tree build. Replace it with a new boolean flag, building_out_of_srctree. I also replaced the conditional ($(srctree),.) because the next commit will allow an absolute path to be used for $(srctree) even when building in the source tree. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
* kbuild: do not create wrappers for header-test-yMasahiro Yamada2019-07-091-5/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | header-test-y does not work with headers in sub-directories. For example, you may want to write a Makefile, like this: include/linux/Kbuild: header-test-y += mtd/nand.h This entry will create a wrapper include/linux/mtd/nand.hdrtest.c with the following content: #include "mtd/nand.h" To make this work, we need to add $(srctree)/include/linux to the header search path. It would be tedious to add ccflags-y. Instead, we could change the *.hdrtest.c rule to wrap: #include "nand.h" This works for in-tree build since #include "..." searches in the relative path from the header with this directive. For O=... build, we need to add $(srctree)/include/linux/mtd to the header search path, which will be even more tedious. After all, I thought it would be handier to compile headers directly without creating wrappers. I added a new build rule to compile %.h into %.h.s The target is %.h.s instead of %.h.o because it is slightly faster. Also, as for GCC, an empty assembly is smaller than an empty object. I wrote the build rule: $(CC) $(c_flags) -S -o $@ -x c /dev/null -include $< instead of: $(CC) $(c_flags) -S -o $@ -x c $< Both work fine with GCC, but the latter is bad for Clang. This comes down to the difference in the -Wunused-function policy. GCC does not warn about unused 'static inline' functions at all. Clang does not warn about the ones in included headers, but does about the ones in the source. So, we should handle headers as headers, not as source files. In fact, this has been hidden since commit abb2ea7dfd82 ("compiler, clang: suppress warning for unused static inline functions"), but we should not rely on that. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Acked-by: Jani Nikula <jani.nikula@intel.com> Tested-by: Jani Nikula <jani.nikula@intel.com>
* kbuild: add support for ensuring headers are self-containedJani Nikula2019-06-151-0/+9
| | | | | | | | | | | | | | Sometimes it's useful to be able to explicitly ensure certain headers remain self-contained, i.e. that they are compilable as standalone units, by including and/or forward declaring everything they depend on. Add special target header-test-y where individual Makefiles can add headers to be tested if CONFIG_HEADER_TEST is enabled. This will generate a dummy C file per header that gets built as part of extra-y. Signed-off-by: Jani Nikula <jani.nikula@intel.com> Reviewed-by: Sam Ravnborg <sam@ravnborg.org> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
* Merge tag 'kbuild-v5.2' of ↵Linus Torvalds2019-05-081-1/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild Pull Kbuild updates from Masahiro Yamada: - allow users to invoke 'make' out of the source tree - refactor scripts/mkmakefile - deprecate KBUILD_SRC, which was used to track the source tree location for O= build. - fix recordmcount.pl in case objdump output is localized - turn unresolved symbols in external modules to errors from warnings by default; pass KBUILD_MODPOST_WARN=1 to get them back to warnings - generate modules.builtin.modinfo to collect .modinfo data from built-in modules - misc Makefile cleanups * tag 'kbuild-v5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (21 commits) .gitignore: add more all*.config patterns moduleparam: Save information about built-in modules in separate file Remove MODULE_ALIAS() calls that take undefined macro .gitignore: add leading and trailing slashes to generated directories scripts/tags.sh: fix direct execution of scripts/tags.sh scripts: override locale from environment when running recordmcount.pl samples: kobject: allow CONFIG_SAMPLE_KOBJECT to become y samples: seccomp: turn CONFIG_SAMPLE_SECCOMP into a bool option kbuild: move Documentation to vmlinux-alldirs kbuild: move samples/ to KBUILD_VMLINUX_OBJS modpost: make KBUILD_MODPOST_WARN also configurable for external modules kbuild: check arch/$(SRCARCH)/include/generated before out-of-tree build kbuild: remove unneeded dependency for include/config/kernel.release memory: squash drivers/memory/Makefile.asm-offsets kbuild: use $(srctree) instead of KBUILD_SRC to check out-of-tree build kbuild: mkmakefile: generate a simple wrapper of top Makefile kbuild: mkmakefile: do not check the generated Makefile marker kbuild: allow Kbuild to start from any directory kbuild: pass $(MAKECMDGOALS) to sub-make as is kbuild: fix warning "overriding recipe for target 'Makefile'" ...
| * kbuild: use $(srctree) instead of KBUILD_SRC to check out-of-tree buildMasahiro Yamada2019-04-021-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | KBUILD_SRC was conventionally used for some different purposes: [1] To remember the source tree path [2] As a flag to check if sub-make is already done [3] As a flag to check if Kbuild runs out of tree For [1], we do not need to remember it because the top Makefile can compute it by $(realpath $(dir $(lastword $(MAKEFILE_LIST)))) [2] has been replaced with self-commenting 'sub_make_done'. For [3], we can distinguish in-tree/out-of-tree by comparing $(srctree) and '.' This commit converts [3] to prepare for the KBUILD_SRC removal. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
* | objtool: Add UACCESS validationPeter Zijlstra2019-04-031-0/+3
|/ | | | | | | | | | | | | | | | | | | | | | | | | It is important that UACCESS regions are as small as possible; furthermore the UACCESS state is not scheduled, so doing anything that might directly call into the scheduler will cause random code to be ran with UACCESS enabled. Teach objtool too track UACCESS state and warn about any CALL made while UACCESS is enabled. This very much includes the __fentry__() and __preempt_schedule() calls. Note that exceptions _do_ save/restore the UACCESS state, and therefore they can drive preemption. This also means that all exception handlers must have an otherwise redundant UACCESS disable instruction; therefore ignore this warning for !STT_FUNC code (exception handlers are not normal functions). Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
* kbuild: strip whitespace in cmd_record_mcount findstringJoe Lawrence2019-03-281-5/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | CC_FLAGS_FTRACE may contain trailing whitespace that interferes with findstring. For example, commit 6977f95e63b9 ("powerpc: avoid -mno-sched-epilog on GCC 4.9 and newer") introduced a change such that on my ppc64le box, CC_FLAGS_FTRACE="-pg -mprofile-kernel ". (Note the trailing space.) When cmd_record_mcount is now invoked, findstring fails as the ftrace flags were found at very end of _c_flags, without the trailing space. _c_flags=" ... -pg -mprofile-kernel" CC_FLAGS_FTRACE="-pg -mprofile-kernel " ^ findstring is looking for this extra space Remove the redundant whitespaces from CC_FLAGS_FTRACE in cmd_record_mcount to avoid this problem. [masahiro.yamada: This issue only happens in the released versions of GNU Make. CC_FLAGS_FTRACE will not contain the trailing space if you use the latest GNU Make, which contains commit b90fabc8d6f3 ("* NEWS: Do not insert a space during '+=' if the value is empty.") ] Suggested-by: Masahiro Yamada <yamada.masahiro@socionext.com> (refactoring) Fixes: 6977f95e63b9 ("powerpc: avoid -mno-sched-epilog on GCC 4.9 and newer"). Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
* kbuild: move archive command to scripts/Makefile.libMasahiro Yamada2019-03-131-5/+1
| | | | | | | | | scripts/Makefile.build and arch/s390/boot/Makefile use the same command (thin archiving with symbol table creation). Avoid the code duplication, and move it to scripts/Makefile.lib. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
* kbuild: hardcode genksyms path and remove GENKSYMS variableMasahiro Yamada2019-02-271-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The genksyms source was integrated into the kernel tree in 2003. I do not expect anybody still using the external /sbin/genksyms. Kbuild does not need to provide the ability to override GENKSYMS. Let's remove the GENKSYMS variable, and use the hardcoded path. Since it occurred in the pre-git era, I attached the commit message in case somebody is interested in the historical background. | Author: Kai Germaschewski <kai@tp1.ruhr-uni-bochum.de> | Date: Wed Feb 19 04:17:28 2003 -0600 | | kbuild: [PATCH] put genksyms in scripts dir | | This puts genksyms into scripts/genksyms/. | | genksyms used to be maintained externally, though the only possible user | was the kernel build. Moving it into the kernel sources makes it easier to | keep it uptodate, like for example updating it to generate linker scripts | directly instead of postprocessing the generated header file fragments | with sed, as we do currently. | | Also, genksyms does not handle __typeof__, which needs to be fixed since | some of the exported symbol in the kernel are defined using __typeof__. | | (Rusty Russell/me) Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
* kbuild: generate modules.order only when CONFIG_MODULES=yMasahiro Yamada2019-02-201-0/+2
| | | | | | | Do not generate pointless modules.order when the module support is disabled. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
* kbuild: Disable extra debugging info in .s outputMasahiro Yamada2019-02-201-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Modern gcc adds view assignments, reset assertion checking in .loc directives and a couple more additional debug markers, which clutters the asm output unnecessarily: For example: bsp_resume: .LFB3466: .loc 1 1868 1 is_stmt 1 view -0 .cfi_startproc .loc 1 1869 2 view .LVU73 # arch/x86/kernel/cpu/common.c:1869: if (this_cpu->c_bsp_resume) .loc 1 1869 14 is_stmt 0 view .LVU74 movq this_cpu(%rip), %rax # this_cpu, this_cpu movq 64(%rax), %rax # this_cpu.94_1->c_bsp_resume, _2 # arch/x86/kernel/cpu/common.c:1869: if (this_cpu->c_bsp_resume) .loc 1 1869 5 view .LVU75 testq %rax, %rax # _2 je .L8 #, .loc 1 1870 3 is_stmt 1 view .LVU76 movq $boot_cpu_data, %rdi #, jmp __x86_indirect_thunk_rax or .loc 2 57 9 view .LVU478 .loc 2 57 9 view .LVU479 .loc 2 57 9 view .LVU480 .loc 2 57 9 view .LVU481 .LBB1385: .LBB1383: .LBB1379: .LBB1377: .LBB1375: .loc 2 57 9 view .LVU482 .loc 2 57 9 view .LVU483 movl %edi, %edx # cpu, cpu .LVL87: .loc 2 57 9 is_stmt 0 view .LVU484 That MOV in there is drowned in debugging information and latter makes it hard to follow the asm. And that DWARF info is not really needed for asm output staring. Disable the debug information generation which clutters the asm output unnecessarily: bsp_resume: # arch/x86/kernel/cpu/common.c:1869: if (this_cpu->c_bsp_resume) movq this_cpu(%rip), %rax # this_cpu, this_cpu movq 64(%rax), %rax # this_cpu.94_1->c_bsp_resume, _2 # arch/x86/kernel/cpu/common.c:1869: if (this_cpu->c_bsp_resume) testq %rax, %rax # _2 je .L8 #, # arch/x86/kernel/cpu/common.c:1870: this_cpu->c_bsp_resume(&boot_cpu_data); movq $boot_cpu_data, %rdi #, jmp __x86_indirect_thunk_rax .L8: # arch/x86/kernel/cpu/common.c:1871: } rep ret .size bsp_resume, .-bsp_resume [ bp: write commit message. ] Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Signed-off-by: Borislav Petkov <bp@suse.de>
* kbuild: remove unnecessary in-subshell executionMasahiro Yamada2019-01-281-2/+2
| | | | | | | The commands surrounded by ( ) are executed in a subshell, but in most cases, we do not need to spawn an extra subshell. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
* kbuild: add real-prereqs shorthand for $(filter-out FORCE,$^)Masahiro Yamada2019-01-281-3/+6
| | | | | | | | | | | | | | | | | | | 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>
* kbuild: remove top-level built-in.aMasahiro Yamada2019-01-281-6/+2
| | | | | | | | | | | | | | The symbol table in the final archive is unneeded; the linker does not require the symbol table after the --whole-archive option. Every object file in the archive is included in the link anyway. Pass thin archives from subdirectories directly to the linker, and remove the final archiving step. Fix up the document and comments as well. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Acked-by: Nicholas Piggin <npiggin@gmail.com>
* Merge tag 'kbuild-v4.21' of ↵Linus Torvalds2018-12-291-79/+49
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild Pull Kbuild updates from Masahiro Yamada: "Kbuild core: - remove unneeded $(call cc-option,...) switches - consolidate Clang compiler flags into CLANG_FLAGS - announce the deprecation of SUBDIRS - fix single target build for external module - simplify the dependencies of 'prepare' stage targets - allow fixdep to directly write to .*.cmd files - simplify dependency generation for CONFIG_TRIM_UNUSED_KSYMS - change if_changed_rule to accept multi-line recipe - move .SECONDARY special target to scripts/Kbuild.include - remove redundant 'set -e' - improve parallel execution for CONFIG_HEADERS_CHECK - misc cleanups Treewide fixes and cleanups - set Clang flags correctly for PowerPC boot images - fix UML build error with CONFIG_GCC_PLUGINS - remove unneeded patterns from .gitignore files - refactor firmware/Makefile - remove unneeded rules for *offsets.s - avoid unneeded regeneration of intermediate .s files - clean up ./Kbuild Modpost: - remove unused -M, -K options - fix false positive warnings about section mismatch - use simple devtable lookup instead of linker magic - misc cleanups Coccinelle: - relax boolinit.cocci checks for overall consistency - fix warning messages of boolinit.cocci Other tools: - improve -dirty check of scripts/setlocalversion - add a tool to generate compile_commands.json from .*.cmd files" * tag 'kbuild-v4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (51 commits) kbuild: remove unused cmd_gentimeconst kbuild: remove $(obj)/ prefixes in ./Kbuild treewide: add intermediate .s files to targets treewide: remove explicit rules for *offsets.s firmware: refactor firmware/Makefile firmware: remove unnecessary patterns from .gitignore scripts: remove unnecessary ihex2fw and check-lc_ctypes from .gitignore um: remove unused filechk_gen_header in Makefile scripts: add a tool to produce a compile_commands.json file kbuild: add -Werror=implicit-int flag unconditionally kbuild: add -Werror=strict-prototypes flag unconditionally kbuild: add -fno-PIE flag unconditionally scripts: coccinelle: Correct warning message scripts: coccinelle: only suggest true/false in files that already use them kbuild: handle part-of-module correctly for *.ll and *.symtypes kbuild: refactor part-of-module kbuild: refactor quiet_modtag kbuild: remove redundant quiet_modtag for $(obj-m) kbuild: refactor Makefile.asm-generic user/Makefile: Fix typo and capitalization in comment section ...
| * kbuild: handle part-of-module correctly for *.ll and *.symtypesMasahiro Yamada2018-12-161-1/+1
| | | | | | | | | | | | | | The single targets *.ll and *.symtypes have never been treated as a module. Fix it. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
| * kbuild: refactor part-of-moduleMasahiro Yamada2018-12-161-5/+3
| | | | | | | | | | | | Use $(foreach ...) to make it shorter. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
| * kbuild: refactor quiet_modtagMasahiro Yamada2018-12-161-6/+1
| | | | | | | | | | | | | | part-of-module and quiet_modtag are set for the same targets. Define quiet_modtag based on part-of-module. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
| * kbuild: remove redundant quiet_modtag for $(obj-m)Masahiro Yamada2018-12-161-2/+0
| | | | | | | | | | | | | | | | | | | | | | All objects in $(obj-m) are contained in $(real-obj-m) as well. It is true composite objects are only contained in $(obj-m), but [M] is hard-coded in quiet_cmd_link_multi-m. This line is redundant. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
| * kbuild: move .SECONDARY special target to Kbuild.includeMasahiro Yamada2018-12-021-4/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In commit 54a702f70589 ("kbuild: mark $(targets) as .SECONDARY and remove .PRECIOUS markers"), I missed one important feature of the .SECONDARY target: .SECONDARY with no prerequisites causes all targets to be treated as secondary. ... which agrees with the policy of Kbuild. Let's move it to scripts/Kbuild.include, with no prerequisites. Note: If an intermediate file is generated by $(call if_changed,...), you still need to add it to "targets" so its .*.cmd file is included. The arm/arm64 crypto files are generated by $(call cmd,shipped), so they do not need to be added to "targets", but need to be added to "clean-files" so "make clean" can properly clean them away. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
| * kbuild: remove redundant 'set -e' from cmd_* definesMasahiro Yamada2018-12-011-2/+0
| | | | | | | | | | | | | | | | | | These three cmd_* are invoked in the $(call cmd,*) form. Now that 'set -e' moved to the 'cmd' macro, they do not need to explicitly give 'set -e'. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
| * kbuild: remove trailing semicolon from cmd_* passed to if_changed_ruleMasahiro Yamada2018-12-011-8/+8
| | | | | | | | | | | | | | With the change of rule_cc_o_c / rule_as_o_S in the last commit, each command is executed in a separate subshell. Rip off unneeded semicolons. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
| * kbuild: change if_changed_rule for multi-line recipeMasahiro Yamada2018-12-011-11/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The 'define' ... 'endef' directive is useful to confine a series of shell commands into a single macro: define foo [action1] [action2] [action3] endif Each action is executed in a separate subshell. However, rule_cc_o_c and rule_as_o_S in scripts/Makefile.build are written as follows (with a trailing semicolon in each cmd_*): define rule_cc_o_c [action1] ; \ [action2] ; \ [action3] ; endef All shell commands are concatenated with '; \' so that it looks like a single command from the Makefile point of view. This does not exploit the benefits of 'define' ... 'endef' form because a single shell command can be more simply written, like this: rule_cc_o_c = \ [action1] ; \ [action2] ; \ [action3] ; I guess the intention for the command concatenation was to let the '@set -e' in if_changed_rule cover all the commands. We can improve the readability by moving '@set -e' to the 'cmd' macro. The combo of $(call echo-cmd,*) $(cmd_*) in rule_cc_o_c and rule_as_o_S have been replaced with $(call cmd,*). The trailing back-slashes have been removed. Here is a note about the performance: the commands in rule_cc_o_c and rule_as_o_S were previously executed all together in a single subshell, but now each line in a separate subshell. This means Make will spawn extra subshells [1]. I measured the build performance for x86_64_defconfig + CONFIG_MODVERSIONS + CONFIG_TRIM_UNUSED_KSYMS and I saw slight performance regression, but I believe code readability and maintainability wins. [1] Precisely, GNU Make may optimize this by executing the command directly instead of forking a subshell, if no shell special characters are found in the command line and omitting the subshell will not change the behavior. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
| * kbuild: simplify dependency generation for CONFIG_TRIM_UNUSED_KSYMSMasahiro Yamada2018-12-011-0/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | My main motivation of this commit is to clean up scripts/Kbuild.include and scripts/Makefile.build. Currently, CONFIG_TRIM_UNUSED_KSYMS works with a tricky gimmick; possibly exported symbols are detected by letting $(CPP) replace EXPORT_SYMBOL* with a special string '=== __KSYM_*===', which is post-processed by sed, and passed to fixdep. The extra preprocessing is costly, and hacking cmd_and_fixdep is ugly. I came up with a new way to find exported symbols; insert a dummy symbol __ksym_marker_* to each potentially exported symbol. Those dummy symbols are picked up by $(NM), post-processed by sed, then appended to .*.cmd files. I collected the post-process part to a new shell script scripts/gen_ksymdeps.sh for readability. The dummy symbols are put into the .discard.* section so that the linker script rips them off the final vmlinux or modules. A nice side-effect is building with CONFIG_TRIM_UNUSED_KSYMS will be much faster. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Reviewed-by: Nicolas Pitre <nico@linaro.org>
| * kbuild: refactor modversions build rulesMasahiro Yamada2018-12-011-37/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Let $(CC) compile objects into normal files *.o instead of .tmp_*.o whether CONFIG_MODVERSIONS is enabled or not. With this, the input file for objtool is always *.o so objtool_o can go away. I guess the reason of using .tmp_*.o for intermediate objects was to avoid leaving incomplete *.o file (, whose timestamp says it is up-to-date) when the genksyms tool failed for some reasons. It no longer matters because any targets are deleted on errors since commit 9c2af1c7377a ("kbuild: add .DELETE_ON_ERROR special target"). Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
| * kbuild: remove redundant 'set -e' from sub_cmd_record_mcountMasahiro Yamada2018-12-011-1/+1
| | | | | | | | | | | | | | This is executed inside the if_changed_rule, which already sets 'set -e'. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
| * kbuild: let fixdep directly write to .*.cmd filesMasahiro Yamada2018-12-011-7/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, fixdep writes dependencies to .*.tmp, which is renamed to .*.cmd after everything succeeds. This is a very safe way to avoid corrupted .*.cmd files. The if_changed_dep has carried this safety mechanism since it was added in 2002. If fixdep fails for some reasons or a user terminates the build while fixdep is running, the incomplete output from the fixdep could be troublesome. This is my insight about some bad scenarios: [1] If the compiler succeeds to generate *.o file, but fixdep fails to write necessary dependencies to .*.cmd file, Make will miss to rebuild the object when headers or CONFIG options are changed. In this case, fixdep should not generate .*.cmd file at all so that 'arg-check' will surely trigger the rebuild of the object. [2] A partially constructed .*.cmd file may not be a syntactically correct makefile. The next time Make runs, it would include it, then fail to parse it. Once this happens, 'make clean' is be the only way to fix it. In fact, [1] is no longer a problem since commit 9c2af1c7377a ("kbuild: add .DELETE_ON_ERROR special target"). Make deletes a target file on any failure in its recipe. Because fixdep is a part of the recipe of *.o target, if it fails, the *.o is deleted anyway. However, I am a bit worried about the slight possibility of [2]. So, here is a solution. Let fixdep directly write to a .*.cmd file, but allow makefiles to include it only when its corresponding target exists. This effectively reverts commit 2982c953570b ("kbuild: remove redundant $(wildcard ...) for cmd_files calculation"), and commit 00d78ab2ba75 ("kbuild: remove dead code in cmd_files calculation in top Makefile") because now we must check the presence of targets. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
* | x86/retpoline: Make CONFIG_RETPOLINE depend on compiler supportZhenzhong Duan2018-11-281-2/+0
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since retpoline capable compilers are widely available, make CONFIG_RETPOLINE hard depend on the compiler capability. Break the build when CONFIG_RETPOLINE is enabled and the compiler does not support it. Emit an error message in that case: "arch/x86/Makefile:226: *** You are building kernel with non-retpoline compiler, please update your compiler.. Stop." [dwmw: Fail the build with non-retpoline compiler] Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: David Woodhouse <dwmw@amazon.co.uk> Cc: Borislav Petkov <bp@suse.de> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Michal Marek <michal.lkml@markovi.net> Cc: <srinivas.eeda@oracle.com> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/cca0cb20-f9e2-4094-840b-fb0f8810cd34@default
* Merge tag 'kbuild-v4.20' of ↵Linus Torvalds2018-10-281-36/+8
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild Pull Kbuild updates from Masahiro Yamada: - optimize kallsyms slightly - remove check for old CFLAGS usage - add some compiler flags unconditionally instead of evaluating $(call cc-option,...) - fix variable shadowing in host tools - refactor scripts/mkmakefile - refactor various makefiles * tag 'kbuild-v4.20' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: modpost: Create macro to avoid variable shadowing ASN.1: Remove unnecessary shadowed local variable kbuild: use 'else ifeq' for checksrc to improve readability kbuild: remove unneeded link_multi_deps kbuild: add -Wno-unused-but-set-variable flag unconditionally kbuild: add -Wdeclaration-after-statement flag unconditionally kbuild: add -Wno-pointer-sign flag unconditionally modpost: remove leftover symbol prefix handling for module device table kbuild: simplify command line creation in scripts/mkmakefile kbuild: do not pass $(objtree) to scripts/mkmakefile kbuild: remove user ID check in scripts/mkmakefile kbuild: remove VERSION and PATCHLEVEL from $(objtree)/Makefile kbuild: add --include-dir flag only for out-of-tree build kbuild: remove dead code in cmd_files calculation in top Makefile kbuild: hide most of targets when running config or mixed targets kbuild: remove old check for CFLAGS use kbuild: prefix Makefile.dtbinst path with $(srctree) unconditionally kallsyms: remove left-over Blackfin code kallsyms: reduce size a little on 64-bit
| * kbuild: use 'else ifeq' for checksrc to improve readabilityMasahiro Yamada2018-10-191-8/+6
| | | | | | | | | | | | | | | | | | | | 'ifeq ... else ifeq ... endif' notation is supported by GNU Make 3.81 or later, which is the requirement for building the kernel since commit 37d69ee30808 ("docs: bump minimal GNU Make version to 3.81"). Use it to improve the readability. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
| * kbuild: remove unneeded link_multi_depsMasahiro Yamada2018-10-191-18/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since commit c8589d1e9e01 ("kbuild: handle multi-objs dependency appropriately"), $^ really represents all the prerequisite of the composite object being built. Hence, $(filter %.o,$^) contains all the objects to link together, which is much simpler than link_multi_deps calculation. Please note $(filter-out FORCE,$^) does not work here. When a single object module is turned into a multi object module, $^ will contain header files that were previously included for building the single object, and recorded in the .*.cmd file. To filter out such headers, $(filter %.o,$^) should be used here. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
| * kbuild: remove old check for CFLAGS useMasahiro Yamada2018-09-121-10/+0
| | | | | | | | | | | | | | | | | | This check has been here for more than a decade since commit 0c53c8e6eb45 ("kbuild: check for wrong use of CFLAGS"). Enough time for migration has passed. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
* | ftrace: Build with CPPFLAGS to get -Qunused-argumentsJoel Stanley2018-09-191-1/+1
|/ | | | | | | | | | | When building to record the mcount locations the kernel uses KBUILD_CFLAGS but not KBUILD_CPPFLAGS. This means it lacks -Qunused-arguments when building with clang, resulting in a lot of noisy warnings. Signed-off-by: Joel Stanley <joel@jms.id.au> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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