From 893ab00439a45513cae55781fc8e3b7108ee1cda Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Sat, 27 Jun 2020 03:59:12 +0900 Subject: kbuild: remove cc-option test of -fno-stack-protector Some Makefiles already pass -fno-stack-protector unconditionally. For example, arch/arm64/kernel/vdso/Makefile, arch/x86/xen/Makefile. No problem report so far about hard-coding this option. So, we can assume all supported compilers know -fno-stack-protector. GCC 4.8 and Clang support this option (https://godbolt.org/z/_HDGzN) Get rid of cc-option from -fno-stack-protector. Remove CONFIG_CC_HAS_STACKPROTECTOR_NONE, which is always 'y'. Note: arch/mips/vdso/Makefile adds -fno-stack-protector twice, first unconditionally, and second conditionally. I removed the second one. Signed-off-by: Masahiro Yamada Reviewed-by: Kees Cook Acked-by: Ard Biesheuvel Reviewed-by: Nick Desaulniers --- Documentation/kbuild/kconfig-language.rst | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'Documentation/kbuild') diff --git a/Documentation/kbuild/kconfig-language.rst b/Documentation/kbuild/kconfig-language.rst index a1601ec3317b..2538e7cb08e6 100644 --- a/Documentation/kbuild/kconfig-language.rst +++ b/Documentation/kbuild/kconfig-language.rst @@ -540,8 +540,8 @@ followed by a test macro:: If you need to expose a compiler capability to makefiles and/or C source files, `CC_HAS_` is the recommended prefix for the config option:: - config CC_HAS_STACKPROTECTOR_NONE - def_bool $(cc-option,-fno-stack-protector) + config CC_HAS_ASM_GOTO + def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC)) Build as module only ~~~~~~~~~~~~~~~~~~~~ -- cgit From 15d5761ad31dfb194ebe76554e6af0437eb20424 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Tue, 7 Jul 2020 18:21:16 +0900 Subject: kbuild: introduce ccflags-remove-y and asflags-remove-y CFLAGS_REMOVE_.o filters out flags when compiling a particular object, but there is no convenient way to do that for every object in a directory. Add ccflags-remove-y and asflags-remove-y to make it easily. Use ccflags-remove-y to clean up some Makefiles. The add/remove order works as follows: [1] KBUILD_CFLAGS specifies compiler flags used globally [2] ccflags-y adds compiler flags for all objects in the current Makefile [3] ccflags-remove-y removes compiler flags for all objects in the current Makefile (New feature) [4] CFLAGS_ adds compiler flags per file. [5] CFLAGS_REMOVE_ removes compiler flags per file. Having [3] before [4] allows us to remove flags from most (but not all) objects in the current Makefile. For example, kernel/trace/Makefile removes $(CC_FLAGS_FTRACE) from all objects in the directory, then adds it back to trace_selftest_dynamic.o and CFLAGS_trace_kprobe_selftest.o The same applies to lib/livepatch/Makefile. Please note ccflags-remove-y has no effect to the sub-directories. In contrast, the previous notation got rid of compiler flags also from all the sub-directories. The following are not affected because they have no sub-directories: arch/arm/boot/compressed/ arch/powerpc/xmon/ arch/sh/ kernel/trace/ However, lib/ has several sub-directories. To keep the behavior, I added ccflags-remove-y to all Makefiles in subdirectories of lib/, except the following: lib/vdso/Makefile - Kbuild does not descend into this Makefile lib/raid/test/Makefile - This is not used for the kernel build I think commit 2464a609ded0 ("ftrace: do not trace library functions") excluded too much. In the next commit, I will remove ccflags-remove-y from the sub-directories of lib/. Suggested-by: Sami Tolvanen Signed-off-by: Masahiro Yamada Acked-by: Steven Rostedt (VMware) Acked-by: Michael Ellerman (powerpc) Acked-by: Brendan Higgins (KUnit) Tested-by: Anders Roxell --- Documentation/kbuild/makefiles.rst | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'Documentation/kbuild') diff --git a/Documentation/kbuild/makefiles.rst b/Documentation/kbuild/makefiles.rst index 6515ebc12b6f..14d8e7d23c04 100644 --- a/Documentation/kbuild/makefiles.rst +++ b/Documentation/kbuild/makefiles.rst @@ -368,6 +368,14 @@ more details, with real examples. subdir-ccflags-y := -Werror + ccflags-remove-y, asflags-remove-y + These flags are used to remove particular flags for the compiler, + assembler invocations. + + Example:: + + ccflags-remove-$(CONFIG_MCOUNT) += -pg + CFLAGS_$@, AFLAGS_$@ CFLAGS_$@ and AFLAGS_$@ only apply to commands in current kbuild makefile. @@ -375,6 +383,9 @@ more details, with real examples. $(CFLAGS_$@) specifies per-file options for $(CC). The $@ part has a literal value which specifies the file that it is for. + CFLAGS_$@ has the higher priority than ccflags-remove-y; CFLAGS_$@ + can re-add compiler flags that were removed by ccflags-remove-y. + Example:: # drivers/scsi/Makefile @@ -387,6 +398,9 @@ more details, with real examples. $(AFLAGS_$@) is a similar feature for source files in assembly languages. + AFLAGS_$@ has the higher priority than asflags-remove-y; AFLAGS_$@ + can re-add assembler flags that were removed by asflags-remove-y. + Example:: # arch/arm/kernel/Makefile -- cgit From 16a122c743b327f714606eff2cd8ff31c206bafc Mon Sep 17 00:00:00 2001 From: "Alexander A. Klimov" Date: Sun, 19 Jul 2020 21:46:02 +0200 Subject: kbuild: Replace HTTP links with HTTPS ones Rationale: Reduces attack surface on kernel devs opening the links for MITM as HTTPS traffic is much harder to manipulate. Deterministic algorithm: For each file: If not .svg: For each line: If doesn't contain `\bxmlns\b`: For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`: If neither `\bgnu\.org/license`, nor `\bmozilla\.org/MPL\b`: If both the HTTP and HTTPS versions return 200 OK and serve the same content: Replace HTTP with HTTPS. Signed-off-by: Alexander A. Klimov Signed-off-by: Masahiro Yamada --- Documentation/kbuild/Kconfig.recursion-issue-02 | 2 +- Documentation/kbuild/kconfig-language.rst | 14 +++++++------- Documentation/kbuild/llvm.rst | 2 +- 3 files changed, 9 insertions(+), 9 deletions(-) (limited to 'Documentation/kbuild') diff --git a/Documentation/kbuild/Kconfig.recursion-issue-02 b/Documentation/kbuild/Kconfig.recursion-issue-02 index b9fd56c4b57e..df245fd7670d 100644 --- a/Documentation/kbuild/Kconfig.recursion-issue-02 +++ b/Documentation/kbuild/Kconfig.recursion-issue-02 @@ -42,7 +42,7 @@ # "select FW_LOADER" [0], in the end the simple alternative solution to this # problem consisted on matching semantics with newly introduced features. # -# [0] http://lkml.kernel.org/r/1432241149-8762-1-git-send-email-mcgrof@do-not-panic.com +# [0] https://lkml.kernel.org/r/1432241149-8762-1-git-send-email-mcgrof@do-not-panic.com mainmenu "Simple example to demo cumulative kconfig recursive dependency implication" diff --git a/Documentation/kbuild/kconfig-language.rst b/Documentation/kbuild/kconfig-language.rst index 2538e7cb08e6..d918c7ed7336 100644 --- a/Documentation/kbuild/kconfig-language.rst +++ b/Documentation/kbuild/kconfig-language.rst @@ -688,10 +688,10 @@ and real world requirements were not well understood. As it stands though only reverse engineering techniques have been used to deduce semantics from variability modeling languages such as Kconfig [3]_. -.. [0] http://www.eng.uwaterloo.ca/~shshe/kconfig_semantics.pdf -.. [1] http://gsd.uwaterloo.ca/sites/default/files/vm-2013-berger.pdf -.. [2] http://gsd.uwaterloo.ca/sites/default/files/ase241-berger_0.pdf -.. [3] http://gsd.uwaterloo.ca/sites/default/files/icse2011.pdf +.. [0] https://www.eng.uwaterloo.ca/~shshe/kconfig_semantics.pdf +.. [1] https://gsd.uwaterloo.ca/sites/default/files/vm-2013-berger.pdf +.. [2] https://gsd.uwaterloo.ca/sites/default/files/ase241-berger_0.pdf +.. [3] https://gsd.uwaterloo.ca/sites/default/files/icse2011.pdf Full SAT solver for Kconfig ~~~~~~~~~~~~~~~~~~~~~~~~~~~ @@ -710,10 +710,10 @@ such efforts somehow on Kconfig. There is enough interest from mentors of existing projects to not only help advise how to integrate this work upstream but also help maintain it long term. Interested developers should visit: -http://kernelnewbies.org/KernelProjects/kconfig-sat +https://kernelnewbies.org/KernelProjects/kconfig-sat -.. [4] http://www.cs.cornell.edu/~sabhar/chapters/SATSolvers-KR-Handbook.pdf -.. [5] http://gsd.uwaterloo.ca/sites/default/files/vm-2013-berger.pdf +.. [4] https://www.cs.cornell.edu/~sabhar/chapters/SATSolvers-KR-Handbook.pdf +.. [5] https://gsd.uwaterloo.ca/sites/default/files/vm-2013-berger.pdf .. [6] https://cados.cs.fau.de .. [7] https://vamos.cs.fau.de .. [8] https://undertaker.cs.fau.de diff --git a/Documentation/kbuild/llvm.rst b/Documentation/kbuild/llvm.rst index c776b6eee969..2aac50b97921 100644 --- a/Documentation/kbuild/llvm.rst +++ b/Documentation/kbuild/llvm.rst @@ -76,7 +76,7 @@ Getting Help Getting LLVM ------------- -- http://releases.llvm.org/download.html +- https://releases.llvm.org/download.html - https://github.com/llvm/llvm-project - https://llvm.org/docs/GettingStarted.html - https://llvm.org/docs/CMake.html -- cgit From faabed295cccc2aba2b67f2e7b309f2892d55004 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Sat, 1 Aug 2020 21:27:18 +0900 Subject: kbuild: introduce hostprogs-always-y and userprogs-always-y To build host programs, you need to add the program names to 'hostprogs' to use the necessary build rule, but it is not enough to build them because there is no dependency. There are two types of host programs: built as the prerequisite of another (e.g. gen_crc32table in lib/Makefile), or always built when Kbuild visits the Makefile (e.g. genksyms in scripts/genksyms/Makefile). The latter is typical in Makefiles under scripts/, which contains host programs globally used during the kernel build. To build them, you need to add them to both 'hostprogs' and 'always-y'. This commit adds hostprogs-always-y as a shorthand. The same applies to user programs. net/bpfilter/Makefile builds bpfilter_umh on demand, hence always-y is unneeded. In contrast, programs under samples/ are added to both 'userprogs' and 'always-y' so they are always built when Kbuild visits the Makefiles. userprogs-always-y works as a shorthand. Signed-off-by: Masahiro Yamada Acked-by: Miguel Ojeda --- Documentation/kbuild/makefiles.rst | 31 ++++++++++++++++++++++++++++++- 1 file changed, 30 insertions(+), 1 deletion(-) (limited to 'Documentation/kbuild') diff --git a/Documentation/kbuild/makefiles.rst b/Documentation/kbuild/makefiles.rst index 14d8e7d23c04..b81b8913a5a3 100644 --- a/Documentation/kbuild/makefiles.rst +++ b/Documentation/kbuild/makefiles.rst @@ -749,6 +749,10 @@ Both possibilities are described in the following. hostprogs := lxdialog always-y := $(hostprogs) + Kbuild provides the following shorthand for this: + + hostprogs-always-y := lxdialog + This will tell kbuild to build lxdialog even if not referenced in any rule. @@ -831,7 +835,32 @@ The syntax is quite similar. The difference is to use "userprogs" instead of 5.4 When userspace programs are actually built ---------------------------------------------- - Same as "When host programs are actually built". + Kbuild builds userspace programs only when told to do so. + There are two ways to do this. + + (1) Add it as the prerequisite of another file + + Example:: + + #net/bpfilter/Makefile + userprogs := bpfilter_umh + $(obj)/bpfilter_umh_blob.o: $(obj)/bpfilter_umh + + $(obj)/bpfilter_umh is built before $(obj)/bpfilter_umh_blob.o + + (2) Use always-y + + Example:: + + userprogs := binderfs_example + always-y := $(userprogs) + + Kbuild provides the following shorthand for this: + + userprogs-always-y := binderfs_example + + This will tell Kbuild to build binderfs_example when it visits this + Makefile. 6 Kbuild clean infrastructure ============================= -- cgit