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2021-05-17kbuild: dummy-tools: adjust to stricter stackprotector checkMichal Kubecek1-1/+5
Commit 3fb0fdb3bbe7 ("x86/stackprotector/32: Make the canary into a regular percpu variable") modified the stackprotector check on 32-bit x86 to check if gcc supports using %fs as canary. Adjust dummy-tools gcc script to pass this new test by returning "%fs" rather than "%gs" if it detects -mstack-protector-guard-reg=fs on command line. Fixes: 3fb0fdb3bbe7 ("x86/stackprotector/32: Make the canary into a regular percpu variable") Signed-off-by: Michal Kubecek <mkubecek@suse.cz> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-04-24kbuild: check the minimum assembler version in KconfigMasahiro Yamada1-0/+6
Documentation/process/changes.rst defines the minimum assembler version (binutils version), but we have never checked it in the build time. Kbuild never invokes 'as' directly because all assembly files in the kernel tree are *.S, hence must be preprocessed. I do not expect raw assembly source files (*.s) would be added to the kernel tree. Therefore, we always use $(CC) as the assembler driver, and commit aa824e0c962b ("kbuild: remove AS variable") removed 'AS'. However, we are still interested in the version of the assembler acting behind. As usual, the --version option prints the version string. $ as --version | head -n 1 GNU assembler (GNU Binutils for Ubuntu) 2.35.1 But, we do not have $(AS). So, we can add the -Wa prefix so that $(CC) passes --version down to the backing assembler. $ gcc -Wa,--version | head -n 1 gcc: fatal error: no input files compilation terminated. OK, we need to input something to satisfy gcc. $ gcc -Wa,--version -c -x assembler /dev/null -o /dev/null | head -n 1 GNU assembler (GNU Binutils for Ubuntu) 2.35.1 The combination of Clang and GNU assembler works in the same way: $ clang -no-integrated-as -Wa,--version -c -x assembler /dev/null -o /dev/null | head -n 1 GNU assembler (GNU Binutils for Ubuntu) 2.35.1 Clang with the integrated assembler fails like this: $ clang -integrated-as -Wa,--version -c -x assembler /dev/null -o /dev/null | head -n 1 clang: error: unsupported argument '--version' to option 'Wa,' For the last case, checking the error message is fragile. If the proposal for -Wa,--version support [1] is accepted, this may not be even an error in the future. One easy way is to check if -integrated-as is present in the passed arguments. We did not pass -integrated-as to CLANG_FLAGS before, but we can make it explicit. Nathan pointed out -integrated-as is the default for all of the architectures/targets that the kernel cares about, but it goes along with "explicit is better than implicit" policy. [2] With all this in my mind, I implemented scripts/as-version.sh to check the assembler version in Kconfig time. $ scripts/as-version.sh gcc GNU 23501 $ scripts/as-version.sh clang -no-integrated-as GNU 23501 $ scripts/as-version.sh clang -integrated-as LLVM 0 [1]: https://github.com/ClangBuiltLinux/linux/issues/1320 [2]: https://lore.kernel.org/linux-kbuild/20210307044253.v3h47ucq6ng25iay@archlinux-ax161/ Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nathan Chancellor <nathan@kernel.org>
2021-03-11kbuild: dummy-tools: adjust to scripts/cc-version.shMasahiro Yamada1-2/+2
Commit aec6c60a01d3 ("kbuild: check the minimum compiler version in Kconfig") changed how the script detects the compiler version. Get 'make CROSS_COMPILE=scripts/dummy-tools/' back working again. Fixes: aec6c60a01d3 ("kbuild: check the minimum compiler version in Kconfig") Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Nathan Chancellor <nathan@kernel.org> Acked-by: Miguel Ojeda <ojeda@kernel.org>
2021-03-11kbuild: dummy-tools: support MPROFILE_KERNEL checks for ppcJiri Slaby1-0/+9
ppc64le checks for -mprofile-kernel to define MPROFILE_KERNEL Kconfig. Kconfig calls arch/powerpc/tools/gcc-check-mprofile-kernel.sh for that purpose. This script performs two checks: 1) build with -mprofile-kernel should contain "_mcount" 2) build with -mprofile-kernel with a function marked as "notrace" should not produce "_mcount" So support this in dummy-tools' gcc, so that we have MPROFILE_KERNEL always true. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-03-09kbuild: dummy-tools: fix inverted tests for gccJiri Slaby1-0/+5
There is a test in Kconfig which takes inverted value of a compiler check: * config CC_HAS_INT128 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) This results in CC_HAS_INT128 not being in super-config generated by dummy-tools. So take this into account in the gcc script. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-01-23kbuild: simplify GCC_PLUGINS enablement in dummy-tools/gccMasahiro Yamada1-7/+3
With commit 1e860048c53e ("gcc-plugins: simplify GCC plugin-dev capability test") applied, this hunk can be way simplified because now scripts/gcc-plugins/Kconfig only checks plugin-version.h Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-04-08kbuild: add dummy toolchains to enable all cc-option etc. in KconfigMasahiro Yamada4-0/+123
Staring v4.18, Kconfig evaluates compiler capabilities, and hides CONFIG options your compiler does not support. This works well if you configure and build the kernel on the same host machine. It is inconvenient if you prepare the .config that is carried to a different build environment (typically this happens when you package the kernel for distros) because using a different compiler potentially produces different CONFIG options than the real build environment. So, you probably want to make as many options visible as possible. In other words, you need to create a super-set of CONFIG options that cover any build environment. If some of the CONFIG options turned out to be unsupported on the build machine, they are automatically disabled by the nature of Kconfig. However, it is not feasible to get a full-featured compiler for every arch. This issue was discussed here: https://lkml.org/lkml/2019/12/9/620 Other than distros, savedefconfig is also a problem. Some arch sub-systems periodically resync defconfig files. If you use a less-capable compiler for savedefconfig, options that do not meet 'depends on $(cc-option,...)' will be forcibly disabled. So, 'make defconfig && make savedefconfig' may silently change the behavior. This commit adds a set of dummy toolchains that pretend to support any feature. Most of compiler features are tested by cc-option, which simply checks the exit code of $(CC). The dummy tools are shell scripts that always exit with 0. So, $(cc-option, ...) is evaluated as 'y'. There are more complicated checks such as: scripts/gcc-x86_{32,64}-has-stack-protector.sh scripts/gcc-plugin.sh scripts/tools-support-relr.sh scripts/dummy-tools/gcc passes all checks. From the top directory of the source tree, you can do: $ make CROSS_COMPILE=scripts/dummy-tools/ oldconfig Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Philipp Rudo <prudo@linux.ibm.com> Tested-by: Jeremy Cline <jcline@redhat.com>