Changes in Makefile

ab09da75 - um: let 'make clean' properly clean underlying SUBARCH as well

Wed, 07 May 2025 07:49:33 +0000

um: let 'make clean' properly clean underlying SUBARCH as wellBuilding the kernel with O= is affected by stale in-tree build artifacts.So, if the source tree is not clean, Kbuild displays the following: $ make ARCH=um O=build defconfig make[1]: Entering directory '/.../linux/build' *** *** The source tree is not clean, please run 'make ARCH=um mrproper' *** in /.../linux *** make[2]: *** [/.../linux/Makefile:673: outputmakefile] Error 1 make[1]: *** [/.../linux/Makefile:248: __sub-make] Error 2 make[1]: Leaving directory '/.../linux/build' make: *** [Makefile:248: __sub-make] Error 2Usually, running 'make mrproper' is sufficient for cleaning the sourcetree for out-of-tree builds.However, building UML generates build artifacts not only in arch/um/,but also in the SUBARCH directory (i.e., arch/x86/). If in-tree stalefiles remain under arch/x86/, Kbuild will reuse them instead of creatingnew ones under the specified build directory.This commit makes 'make ARCH=um clean' recurse into the SUBARCH directory.Reported-by: Shuah Khan Closes: https://lore.kernel.org/lkml/20250502172459.14175-1-skhan@linuxfoundation.org/Signed-off-by: Masahiro Yamada Acked-by: Johannes Berg Reviewed-by: David Gow Reviewed-by: Shuah Khan List of files: /linux-6.15/arch/um/Makefile

2f278b59 - um: always include kconfig.h and compiler-version.h

Sun, 03 Nov 2024 15:05:03 +0000

um: always include kconfig.h and compiler-version.hSince commit a95b37e20db9 ("kbuild: get out of") we can safely include these files in userspace code.Doing so simplifies matters as options do not need to be exported viaasm-offsets.h anymore.Signed-off-by: Benjamin Berg Link: https://patch.msgid.link/20241103150506.1367695-2-benjamin@sipsolutions.netSigned-off-by: Johannes Berg List of files: /linux-6.15/arch/um/Makefile

32e8eaf2 - um: use execveat to create userspace MMs

Thu, 19 Sep 2024 12:45:03 +0000

um: use execveat to create userspace MMsUsing clone will not undo features that have been enabled by libc. Anexample of this already happening is rseq, which could cause the kernelto read/write memory of the userspace process. In the future thestandard library might also use mseal by default to protect itself,which would also thwart our attempts at unmapping everything.Solve all this by taking a step back and doing an execve into a tinystatic binary that sets up the minimal environment required for thestub without using any standard library. That way we have a cleanexecution environment that is fully under the control of UML.Note that this changes things a bit as the FDs are not anymore sharedwith the kernel. Instead, we explicitly share the FDs for the physicalmemory and all existing iomem regions. Doing this is fine, as iomemregions cannot be added at runtime.Signed-off-by: Benjamin Berg Link: https://patch.msgid.link/20240919124511.282088-3-benjamin@sipsolutions.net[use pipe() instead of pipe2(), remove unneeded close() calls]Signed-off-by: Johannes Berg List of files: /linux-6.15/arch/um/Makefile

19ee6923 - um: Makefile: use bash from the environment

Sat, 23 Mar 2024 17:44:25 +0000

um: Makefile: use bash from the environmentSet Makefile SHELL to bash instead of /bin/bash for better portability.Some systems do not install binaries to /bin, and therefore do notprovide /bin/bash. This includes Linux distros which intentionally avoidimplementing the Filesystem Hierarchy Standard (FHS), such as NixOS andGuix System.The recipies inside arch/um/Makefile don't require top-level Bash tobuild, and setting "SHELL" to "bash" makes Make pick the Bash executablefrom the environment, hence this patch.Changes since last roll:- Rebase onto a more recent commit on the master branch.- Remove a dangling in-text citation from the change log.- Reword the change log.Signed-off-by: Yueh-Shun Li Reviewed-by: Johannes Berg List of files: /linux-6.15/arch/um/Makefile

846cfbee - um: Fix adding '-no-pie' for clang

Tue, 23 Jan 2024 22:59:54 +0000

um: Fix adding '-no-pie' for clangThe kernel builds with -fno-PIE, so commit 883354afbc10 ("um: linkvmlinux with -no-pie") added the compiler linker flag '-no-pie' viacc-option because '-no-pie' was only supported in GCC 6.1.0 and newer.While this works for GCC, this does not work for clang because cc-optionuses '-c', which stops the pipeline right before linking, so '-no-pie'is unconsumed and clang warns, causing cc-option to fail just as itwould if the option was entirely unsupported: $ clang -Werror -no-pie -c -o /dev/null -x c /dev/null clang-16: error: argument unused during compilation: '-no-pie' [-Werror,-Wunused-command-line-argument]A recent version of clang exposes this because it generates a relocationunder '-mcmodel=large' that is not supported in PIE mode: /usr/sbin/ld: init/main.o: relocation R_X86_64_32 against symbol `saved_command_line' can not be used when making a PIE object; recompile with -fPIE /usr/sbin/ld: failed to set dynamic section sizes: bad value clang: error: linker command failed with exit code 1 (use -v to see invocation)Remove the cc-option check altogether. It is wasteful to invoke thecompiler to check for '-no-pie' because only one supported compilerversion does not support it, GCC 5.x (as it is supported with theminimum version of clang and GCC 6.1.0+). Use a combination of thegcc-min-version macro and CONFIG_CC_IS_CLANG to unconditionally add'-no-pie' with CONFIG_LD_SCRIPT_DYN=y, so that it is enabled with allcompilers that support this. Furthermore, using gcc-min-version can helpturn this back into LINK-$(CONFIG_LD_SCRIPT_DYN) += -no-piewhen the minimum version of GCC is bumped past 6.1.0.Cc: stable@vger.kernel.orgCloses: https://github.com/ClangBuiltLinux/linux/issues/1982Signed-off-by: Nathan Chancellor Signed-off-by: Masahiro Yamada List of files: /linux-6.15/arch/um/Makefile

8f85f93b - um: use obj-y to descend into arch/um/*/

Fri, 21 Jul 2023 17:18:57 +0000

um: use obj-y to descend into arch/um/*/The single build rule does not work with the core-y syntax. [1]Use the standard obj-y syntax.[1]: https://lore.kernel.org/linux-kbuild/d57ba55f-20a3-b836-783d-b49c8a161b6e@kernel.org/T/#m7bc402e1e038f00ebcf2e92ed7fcb8a52fc1ea44Signed-off-by: Masahiro Yamada Tested-by: Jiri Slaby Reviewed-by: Nick Desaulniers Tested-by: Nick Desaulniers Signed-off-by: Richard Weinberger List of files: /linux-6.15/arch/um/Makefile

d32df108 - um: Hard-code the result of 'uname -s'

Fri, 21 Jul 2023 17:18:56 +0000

um: Hard-code the result of 'uname -s'We rely on 'uname -s' returning 'Linux' because there are os-Linux/directories, but no other os-*/.Supporting a non-Linux host is unlikely to happen.Let's hard-code 'Linux'.Signed-off-by: Masahiro Yamada Signed-off-by: Richard Weinberger List of files: /linux-6.15/arch/um/Makefile

a5a319ec - um: Use HOST_DIR for mrproper

Tue, 06 Jun 2023 22:24:45 +0000

um: Use HOST_DIR for mrproperWhen HEADER_ARCH was introduced, the MRPROPER_FILES (then MRPROPER_DIRS)list wasn't adjusted, leaving SUBARCH as part of the path argument.This resulted in the "mrproper" target not cleaning up arch/x86/... whenSUBARCH was specified. Since HOST_DIR is arch/$(HEADER_ARCH), use itinstead to get the correct path.Cc: Richard Weinberger Cc: Anton Ivanov Cc: Johannes Berg Cc: Azeem Shaikh Cc: linux-um@lists.infradead.orgFixes: 7bbe7204e937 ("um: merge Makefile-{i386,x86_64}")Cc: stable@vger.kernel.orgSigned-off-by: Kees Cook Link: https://lore.kernel.org/r/20230606222442.never.807-kees@kernel.org List of files: /linux-6.15/arch/um/Makefile

83e913f5 - um: Support LTO

Fri, 13 Jan 2023 17:03:00 +0000

um: Support LTOOnly a handful of changes are necessary to get it to work.Signed-off-by: Peter Foley Signed-off-by: Richard Weinberger List of files: /linux-6.15/arch/um/Makefile

6aa56115 - um: Use CFLAGS_vmlinux

Fri, 13 Jan 2023 04:49:10 +0000

um: Use CFLAGS_vmlinuxlink-vmlinux.sh doesn't use LDFLAGS_vmlinux when linking the kernel forUML. Move the LDFLAGS_EXESTACK options into CFLAGS_vmlinux so they'reactually respected.e.g./usr/lib/gcc/x86_64-pc-linux-gnu/12/../../../../x86_64-pc-linux-gnu/bin/ld: warning: .tmp_vmlinux.kallsyms3.o: missing .note.GNU-stack section implies executable stack/usr/lib/gcc/x86_64-pc-linux-gnu/12/../../../../x86_64-pc-linux-gnu/bin/ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker/usr/lib/gcc/x86_64-pc-linux-gnu/12/../../../../x86_64-pc-linux-gnu/bin/ld: warning: vmlinux has a LOAD segment with RWX permissionsReviewed-by: David Gow Signed-off-by: Peter Foley Signed-off-by: Richard Weinberger List of files: /linux-6.15/arch/um/Makefile

905a7707 - rust: arch/um: Use 'pie' relocation mode under UML

Sat, 17 Dec 2022 04:44:34 +0000

rust: arch/um: Use 'pie' relocation mode under UMLUML expects a position independent executable for some reason, so tellrustc to generate pie objects. Otherwise we get a bunch of relocationswe can't deal with in libcore.Signed-off-by: David Gow Signed-off-by: Richard Weinberger List of files: /linux-6.15/arch/um/Makefile

bd71558d - arch: um: Mark the stack non-executable to fix a binutils warning

Wed, 21 Sep 2022 06:48:55 +0000

arch: um: Mark the stack non-executable to fix a binutils warningSince binutils 2.39, ld will print a warning if any stack section isexecutable, which is the default for stack sections on files without a.note.GNU-stack section.This was fixed for x86 in commit ffcf9c5700e4 ("x86: link vdso and boot with -z noexecstack --no-warn-rwx-segments"),but remained broken for UML, resulting in several warnings:/usr/bin/ld: warning: arch/x86/um/vdso/vdso.o: missing .note.GNU-stack section implies executable stack/usr/bin/ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker/usr/bin/ld: warning: .tmp_vmlinux.kallsyms1 has a LOAD segment with RWX permissions/usr/bin/ld: warning: .tmp_vmlinux.kallsyms1.o: missing .note.GNU-stack section implies executable stack/usr/bin/ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker/usr/bin/ld: warning: .tmp_vmlinux.kallsyms2 has a LOAD segment with RWX permissions/usr/bin/ld: warning: .tmp_vmlinux.kallsyms2.o: missing .note.GNU-stack section implies executable stack/usr/bin/ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker/usr/bin/ld: warning: vmlinux has a LOAD segment with RWX permissionsLink both the VDSO and vmlinux with -z noexecstack, fixing the warningsabout .note.GNU-stack sections. In addition, pass --no-warn-rwx-segmentsto dodge the remaining warnings about LOAD segments with RWX permissionsin the kallsyms objects. (Note that this flag is apparently notavailable on lld, so hide it behind a test for BFD, which is what thex86 patch does.)Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ffcf9c5700e49c0aee42dcba9a12ba21338e8136Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=ba951afb99912da01a6e8434126b8fac7aa75107Signed-off-by: David Gow Reviewed-by: Lukas Straub Tested-by: Lukas Straub Acked-by: Randy Dunlap # build-testedSigned-off-by: Richard Weinberger List of files: /linux-6.15/arch/um/Makefile

1e39036d - Revert "um: clang: Strip out -mno-global-merge from USER_CFLAGS"

Wed, 30 Mar 2022 23:45:28 +0000

Revert "um: clang: Strip out -mno-global-merge from USER_CFLAGS"This reverts commit 6580c5c18fb3df2b11c5e0452372f815deeff895.This patch is buggy, as noted in the patch linked below. The root causehas been solved by removing '-mno-global-merge' for the entire kernel.Link: https://lore.kernel.org/r/20220322173547.677760-1-nathan@kernel.org/Signed-off-by: Nathan Chancellor Reviewed-by: David Gow Reviewed-by: Kees Cook Signed-off-by: Masahiro Yamada List of files: /linux-6.15/arch/um/Makefile

6580c5c1 - um: clang: Strip out -mno-global-merge from USER_CFLAGS

Thu, 03 Mar 2022 09:06:42 +0000

um: clang: Strip out -mno-global-merge from USER_CFLAGSThe things built with USER_CFLAGS don't seem to recognise it as acompiler option, and print a warning:clang: warning: argument unused during compilation: '-mno-global-merge' [-Wunused-command-line-argument]Fixes: 744814d2fa ("um: Allow builds with Clang")Signed-off-by: David Gow Reviewed-by: Nathan Chancellor Signed-off-by: Richard Weinberger List of files: /linux-6.15/arch/um/Makefile

d8285639 - kbuild: do not require sub-make for separate output tree builds

Sat, 24 Jul 2021 18:35:56 +0000

kbuild: do not require sub-make for separate output tree buildsAs explained in commit 3204a7fb98a3 ("kbuild: prefix $(srctree)/ to someincluded Makefiles"), I want to stop using --include-dir some day.I already fixed up the top Makefile, but some arch Makefiles (mips, um,x86) still include check-in Makefiles without $(srctree)/.Fix them up so 'need-sub-make := 1' can go away for this case.Signed-off-by: Masahiro Yamada List of files: /linux-6.15/arch/um/Makefile

386093c6 - um: allow not setting extra rpaths in the linux binary

Mon, 08 Mar 2021 13:02:37 +0000

um: allow not setting extra rpaths in the linux binaryThere doesn't seem to be any reason for the rpath being set inthe binaries, at on systems that I tested on. On the other hand,setting rpath is actually harming binaries in some cases, e.g.if using nix-based compilation environments where /lib & /lib64are not part of the actual environment.Add a new Kconfig option (under EXPERT, for less user confusion)that allows disabling the rpath additions.Signed-off-by: Johannes Berg Signed-off-by: Richard Weinberger List of files: /linux-6.15/arch/um/Makefile

893ab004 - kbuild: remove cc-option test of -fno-stack-protector

Fri, 26 Jun 2020 18:59:12 +0000

kbuild: remove cc-option test of -fno-stack-protectorSome 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 canassume 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, firstunconditionally, 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 List of files: /linux-6.15/arch/um/Makefile

0663c68c - kbuild: remove {CLEAN,MRPROPER,DISTCLEAN}_DIRS

Mon, 04 May 2020 08:08:07 +0000

kbuild: remove {CLEAN,MRPROPER,DISTCLEAN}_DIRSMerge {CLEAN,MRPROPER,DISTCLEAN}_DIRS into {CLEAN,MRPROPER,DISTCLEAN}_FILESbecause the difference is just the -r option passed to the 'rm' command.Do likewise as commit 1634f2bfdb84 ("kbuild: remove clean-dirs syntax").Signed-off-by: Masahiro Yamada List of files: /linux-6.15/arch/um/Makefile

63ec90f1 - um: ensure `make ARCH=um mrproper` removes arch/$(SUBARCH)/include/generated/

Wed, 22 Apr 2020 00:48:44 +0000

um: ensure `make ARCH=um mrproper` removes arch/$(SUBARCH)/include/generated/In this workflow:$ make ARCH=um defconfig && make ARCH=um -j8 [snip]$ make ARCH=um mrproper [snip]$ make ARCH=um defconfig O=./build_um && make ARCH=um -j8 O=./build_um [snip] CC scripts/mod/empty.oIn file included from ../include/linux/types.h:6, from ../include/linux/mod_devicetable.h:12, from ../scripts/mod/devicetable-offsets.c:3:../include/uapi/linux/types.h:5:10: fatal error: asm/types.h: No such file or directory 5 | #include | ^~~~~~~~~~~~~compilation terminated.make[2]: *** [../scripts/Makefile.build:100: scripts/mod/devicetable-offsets.s] Error 1make[2]: *** Waiting for unfinished jobs....make[1]: *** [/home/iha/sdb/opensource/lkmp/linux-kselftest.git/Makefile:1140: prepare0] Error 2make[1]: Leaving directory '/home/iha/sdb/opensource/lkmp/linux-kselftest.git/build_um'make: *** [Makefile:180: sub-make] Error 2The cause of the error was because arch/$(SUBARCH)/include/generated filesweren't properly cleaned by `make ARCH=um mrproper`.Fixes: a788b2ed81ab ("kbuild: check arch/$(SRCARCH)/include/generated before out-of-tree build")Reported-by: Theodore Ts'o Suggested-by: Masahiro Yamada Signed-off-by: Vitor Massaru Iha Reviewed-by: Brendan Higgins Tested-by: Brendan Higgins Link: https://groups.google.com/forum/#!msg/kunit-dev/QmA27YEgEgI/hvS1kiz2CwAJSigned-off-by: Masahiro Yamada List of files: /linux-6.15/arch/um/Makefile

75dd4747 - kbuild: remove src and obj from the top Makefile

Sat, 06 Jul 2019 03:07:11 +0000

kbuild: remove src and obj from the top MakefileReplace $(src) and $(obj) with $(srctree) and $(objtree), respectively.Signed-off-by: Masahiro Yamada List of files: /linux-6.15/arch/um/Makefile