kernel/linux.git/init/Kconfig, branch v5.15.209

sched/isolation: Make CONFIG_CPU_ISOLATION depend on CONFIG_SMP

2025-05-02T05:44:36+00:00

[ Upstream commit 975776841e689dd8ba36df9fa72ac3eca3c2957a ] kernel/sched/isolation.c obviously makes no sense without CONFIG_SMP, but the Kconfig entry we have right now: config CPU_ISOLATION bool "CPU isolation" depends on SMP || COMPILE_TEST allows the creation of pointless .config's which cause build failures. Reported-by: kernel test robot Signed-off-by: Oleg Nesterov Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20250330134955.GA7910@redhat.com Closes: https://lore.kernel.org/oe-kbuild-all/202503260646.lrUqD3j5-lkp@intel.com/ Signed-off-by: Sasha Levin

module: sign with sha512 instead of sha1 by default

2025-05-02T05:44:25+00:00

commit f3b93547b91ad849b58eb5ab2dd070950ad7beb3 upstream. Switch away from using sha1 for module signing by default and use the more modern sha512 instead, which is what among others Arch, Fedora, RHEL, and Ubuntu are currently using for their kernels. Sha1 has not been considered secure against well-funded opponents since 2005[1]; since 2011 the NIST and other organizations furthermore recommended its replacement[2]. This is why OpenSSL on RHEL9, Fedora Linux 41+[3], and likely some other current and future distributions reject the creation of sha1 signatures, which leads to a build error of allmodconfig configurations: 80A20474797F0000:error:03000098:digital envelope routines:do_sigver_init:invalid digest:crypto/evp/m_sigver.c:342: make[4]: *** [.../certs/Makefile:53: certs/signing_key.pem] Error 1 make[4]: *** Deleting file 'certs/signing_key.pem' make[4]: *** Waiting for unfinished jobs.... make[3]: *** [.../scripts/Makefile.build:478: certs] Error 2 make[2]: *** [.../Makefile:1936: .] Error 2 make[1]: *** [.../Makefile:224: __sub-make] Error 2 make[1]: Leaving directory '...' make: *** [Makefile:224: __sub-make] Error 2 This change makes allmodconfig work again and sets a default that is more appropriate for current and future users, too. Link: https://www.schneier.com/blog/archives/2005/02/cryptanalysis_o.html [1] Link: https://csrc.nist.gov/projects/hash-functions [2] Link: https://fedoraproject.org/wiki/Changes/OpenSSLDistrustsha1SigVer [3] Signed-off-by: Thorsten Leemhuis Reviewed-by: Sami Tolvanen Tested-by: kdevops [0] Link: https://github.com/linux-kdevops/linux-modules-kpd/actions/runs/11420092929/job/31775404330 [0] Link: https://lore.kernel.org/r/52ee32c0c92afc4d3263cea1f8a1cdc809728aff.1729088288.git.linux@leemhuis.info Signed-off-by: Petr Pavlu Signed-off-by: Greg Kroah-Hartman

kbuild: Add CONFIG_PAHOLE_VERSION

2023-02-25T11:06:45+00:00

commit 613fe169237785a4bb1d06397b52606b2967da53 upstream. There are a few different places where pahole's version is turned into a three digit form with the exact same command. Move this command into scripts/pahole-version.sh to reduce the amount of duplication across the tree. Create CONFIG_PAHOLE_VERSION so the version code can be used in Kconfig to enable and disable configuration options based on the pahole version, which is already done in a couple of places. Signed-off-by: Nathan Chancellor Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20220201205624.652313-3-nathan@kernel.org Signed-off-by: Matthias Maennich Signed-off-by: Greg Kroah-Hartman

init/Kconfig: fix CC_HAS_ASM_GOTO_TIED_OUTPUT test with dash

2022-12-02T16:41:08+00:00

[ Upstream commit 534bd70374d646f17e2cebe0e6e4cdd478ce4f0c ] When using dash as /bin/sh, the CC_HAS_ASM_GOTO_TIED_OUTPUT test fails with a syntax error which is not the one we are looking for: : In function ‘foo’: :1:29: warning: missing terminating " character :1:29: error: missing terminating " character :2:5: error: expected ‘:’ before ‘+’ token :2:7: warning: missing terminating " character :2:7: error: missing terminating " character :2:5: error: expected declaration or statement at end of input Removing '\n' solves this. Fixes: 1aa0e8b144b6 ("Kconfig: Add option for asm goto w/ tied outputs to workaround clang-13 bug") Signed-off-by: Alexandre Belloni Reviewed-by: Sean Christopherson Signed-off-by: Masahiro Yamada Signed-off-by: Sasha Levin

Kconfig: Add option for asm goto w/ tied outputs to workaround clang-13 bug

2022-06-09T08:23:26+00:00

commit 1aa0e8b144b6474c4914439d232d15bfe883636b upstream. Add a config option to guard (future) usage of asm_volatile_goto() that includes "tied outputs", i.e. "+" constraints that specify both an input and output parameter. clang-13 has a bug[1] that causes compilation of such inline asm to fail, and KVM wants to use a "+m" constraint to implement a uaccess form of CMPXCHG[2]. E.g. the test code fails with :1:29: error: invalid operand in inline asm: '.long (${1:l}) - .' int foo(int *x) { asm goto (".long (%l[bar]) - .\n": "+m"(*x) ::: bar); return *x; bar: return 0; } ^ :1:29: error: unknown token in expression :1:9: note: instantiated into assembly here .long () - . ^ 2 errors generated. on clang-13, but passes on gcc (with appropriate asm goto support). The bug is fixed in clang-14, but won't be backported to clang-13 as the changes are too invasive/risky. gcc also had a similar bug[3], fixed in gcc-11, where gcc failed to account for its behavior of assigning two numbers to tied outputs (one for input, one for output) when evaluating symbolic references. [1] https://github.com/ClangBuiltLinux/linux/issues/1512 [2] https://lore.kernel.org/all/YfMruK8%2F1izZ2VHS@google.com [3] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98096 Suggested-by: Nick Desaulniers Reviewed-by: Nick Desaulniers Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson Message-Id: <20220202004945.2540433-2-seanjc@google.com> Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman

kbuild: Only default to -Werror if COMPILE_TEST

2021-09-08T01:47:04+00:00

The cross-product of the kernel's supported toolchains, architectures, and configuration options is large. So large, that it's generally accepted to be infeasible to enumerate and build+test them all (many compile-testers rely on randomly generated configs). Without the possibility to enumerate all possible combinations of toolchains, architectures, and configuration options, it is inevitable that compiler warnings in this space exist. With -Werror, this means that an innumerable set of kernels are now broken, yet had been perfectly usable before (confused compilers, code with warnings unused, or luck). Distributors will necessarily pick a point in the toolchain X arch X config space, and if unlucky, will have a broken build. Granted, those will likely disable CONFIG_WERROR and move on. The kernel's default configuration is unlikely to be suitable for all users, but it's inappropriate to force many users to set CONFIG_WERROR=n. This also holds for CI systems which are focused on runtime testing, where the odd warning in some subsystem will disrupt testing of the rest of the kernel. Many of those runtime-focused CI systems run tests or fuzz the kernel using runtime debugging tools. Runtime testing of different subsystems can proceed in parallel, and potentially uncover serious bugs; halting runtime testing of the entire kernel because of the odd warning (now error) in a subsystem or driver is simply inappropriate. Therefore, runtime-focused CI systems will likely choose CONFIG_WERROR=n as well. The appropriate usecase for -Werror is therefore compile-test focused builds (often done by developers or CI systems). Reflect this in the Kconfig option by making the default value of WERROR match COMPILE_TEST. Signed-off-by: Marco Elver Acked-by: Guenter Roeck Acked-by: Randy Dunlap Reviwed-by: Mark Brown Reviewed-by: Nathan Chancellor Signed-off-by: Linus Torvalds

Enable '-Werror' by default for all kernel builds

2021-09-05T18:24:05+00:00

... but make it a config option so that broken environments can disable it when required. We really should always have a clean build, and will disable specific over-eager warnings as required, if we can't fix them. But while I fairly religiously enforce that in my own tree, it doesn't get enforced by various build robots that don't necessarily report warnings. So this just makes '-Werror' a default compiler flag, but allows people to disable it for their configuration if they have some particular issues. Occasionally, new compiler versions end up enabling new warnings, and it can take a while before we have them fixed (or the warnings disabled if that is what it takes), so the config option allows for that situation. Hopefully this will mean that I get fewer pull requests that have new warnings that were not noticed by various automation we have in place. Knock wood. Signed-off-by: Linus Torvalds

Merge tag 'printk-for-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux

2021-09-02T01:41:13+00:00

Pull printk updates from Petr Mladek: - Optionally, provide an index of possible printk messages via /printk/index/. It can be used when monitoring important kernel messages on a farm of various hosts. The monitor has to be updated when some messages has changed or are not longer available by a newly deployed kernel. - Add printk.console_no_auto_verbose boot parameter. It allows to generate crash dump even with slow consoles in a reasonable time frame. - Remove printk_safe buffers. The messages are always stored directly to the main logbuffer, even in NMI or recursive context. Also it allows to serialize syslog operations by a mutex instead of a spin lock. - Misc clean up and build fixes. * tag 'printk-for-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: printk/index: Fix -Wunused-function warning lib/nmi_backtrace: Serialize even messages about idle CPUs printk: Add printk.console_no_auto_verbose boot parameter printk: Remove console_silent() lib/test_scanf: Handle n_bits == 0 in random tests printk: syslog: close window between wait and read printk: convert @syslog_lock to mutex printk: remove NMI tracking printk: remove safe buffers printk: track/limit recursion lib/nmi_backtrace: explicitly serialize banner and regs printk: Move the printk() kerneldoc comment to its new home printk/index: Fix warning about missing prototypes MIPS/asm/printk: Fix build failure caused by printk printk: index: Add indexing support to dev_printk printk: Userspace format indexing support printk: Rework parse_prefix into printk_parse_prefix printk: Straighten out log_flags into printk_info_flags string_helpers: Escape double quotes in escape_special printk/console: Check consistent sequence number when handling race in console_unlock()

Merge branch 'rework/printk_safe-removal' into for-linus

2021-08-30T14:36:10+00:00

printk: remove NMI tracking

2021-07-26T13:09:44+00:00

All NMI contexts are handled the same as the safe context: store the message and defer printing. There is no need to have special NMI context tracking for this. Using in_nmi() is enough. There are several parts of the kernel that are manually calling into the printk NMI context tracking in order to cause general printk deferred printing: arch/arm/kernel/smp.c arch/powerpc/kexec/crash.c kernel/trace/trace.c For arm/kernel/smp.c and powerpc/kexec/crash.c, provide a new function pair printk_deferred_enter/exit that explicitly achieves the same objective. For ftrace, remove the printk context manipulation completely. It was added in commit 03fc7f9c99c1 ("printk/nmi: Prevent deadlock when accessing the main log buffer in NMI"). The purpose was to enforce storing messages directly into the ring buffer even in NMI context. It really should have only modified the behavior in NMI context. There is no need for a special behavior any longer. All messages are always stored directly now. The console deferring is handled transparently in vprintk(). Signed-off-by: John Ogness [pmladek@suse.com: Remove special handling in ftrace.c completely. Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/20210715193359.25946-5-john.ogness@linutronix.de