kernel/linux.git/lib/Kconfig.kcsan, branch v6.6.131

Merge tag 'kcsan.2023.02.24a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

2023-02-25T21:02:20+00:00

Pull kernel concurrency sanitizer (KCSAN) updates from Paul McKenney: "This fixes gcc-11 errors for x86_64 KCSAN-enabled kernel builds by selecting the CONSTRUCTORS Kconfig option" * tag 'kcsan.2023.02.24a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: kcsan: select CONFIG_CONSTRUCTORS

kcsan: select CONFIG_CONSTRUCTORS

2023-02-22T18:28:20+00:00

Building a kcsan enabled kernel for x86_64 with gcc-11 results in a lot of build warnings or errors without CONFIG_CONSTRUCTORS: x86_64-linux-ld: error: unplaced orphan section `.ctors.65436' from `arch/x86/lib/copy_mc.o' x86_64-linux-ld: error: unplaced orphan section `.ctors.65436' from `arch/x86/lib/cpu.o' x86_64-linux-ld: error: unplaced orphan section `.ctors.65436' from `arch/x86/lib/csum-partial_64.o' x86_64-linux-ld: error: unplaced orphan section `.ctors.65436' from `arch/x86/lib/csum-wrappers_64.o' x86_64-linux-ld: error: unplaced orphan section `.ctors.65436' from `arch/x86/lib/insn-eval.o' x86_64-linux-ld: error: unplaced orphan section `.ctors.65436' from `arch/x86/lib/insn.o' x86_64-linux-ld: error: unplaced orphan section `.ctors.65436' from `arch/x86/lib/misc.o' The same thing has been reported for mips64. I can't reproduce it for any other compiler version, so I don't know if constructors are always required here or if this is a gcc-11 specific implementation detail. I see no harm in always enabling constructors here, and this reliably fixes the build warnings for me. Link: https://lore.kernel.org/lkml/202204181801.r3MMkwJv-lkp@intel.com/T/ Cc: Kees Cook See-also: 3e6631485fae ("vmlinux.lds.h: Keep .ctors.* with .ctors") Signed-off-by: Arnd Bergmann Reviewed-by: Marco Elver Signed-off-by: Paul E. McKenney

lib: Kconfig: fix spellos

2023-01-25T00:21:26+00:00

Fix spelling in lib/ Kconfig files. (reported by codespell) Link: https://lkml.kernel.org/r/20230124181655.16269-1-rdunlap@infradead.org Cc: Andrew Morton Cc: Marco Elver Cc: Dmitry Vyukov Cc: kasan-dev@googlegroups.com Reviewed-by: Marco Elver Signed-off-by: Randy Dunlap Signed-off-by: Steven Rostedt (Google)

kcsan: Fix trivial typo in Kconfig help comments

2022-10-18T22:07:33+00:00

Fix trivial typo in Kconfig help comments in KCSAN_SKIP_WATCH and KCSAN_SKIP_WATCH_RANDOMIZE Signed-off-by: Ryosuke Yasuoka Reviewed-by: Marco Elver Signed-off-by: Paul E. McKenney

objtool: Make noinstr hacks optional

2022-04-22T10:32:04+00:00

Objtool has some hacks in place to workaround toolchain limitations which otherwise would break no-instrumentation rules. Make the hacks explicit (and optional for other arches) by turning it into a cmdline option and kernel config option. Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Miroslav Benes Link: https://lkml.kernel.org/r/b326eeb9c33231b9dfbb925f194ed7ee40edcd7c.1650300597.git.jpoimboe@redhat.com

objtool: Add CONFIG_OBJTOOL

2022-04-22T10:32:03+00:00

Now that stack validation is an optional feature of objtool, add CONFIG_OBJTOOL and replace most usages of CONFIG_STACK_VALIDATION with it. CONFIG_STACK_VALIDATION can now be considered to be frame-pointer specific. CONFIG_UNWINDER_ORC is already inherently valid for live patching, so no need to "validate" it. Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Miroslav Benes Link: https://lkml.kernel.org/r/939bf3d85604b2a126412bf11af6e3bd3b872bcb.1650300597.git.jpoimboe@redhat.com

Revert "ubsan, kcsan: Don't combine sanitizer with kcov on clang"

2022-03-24T02:00:35+00:00

This reverts commit ea91a1d45d19469001a4955583187b0d75915759. Since df05c0e9496c ("Documentation: Raise the minimum supported version of LLVM to 11.0.0") the minimum Clang version is now 11.0, which fixed the UBSAN/KCSAN vs. KCOV incompatibilities. Link: https://bugs.llvm.org/show_bug.cgi?id=45831 Link: https://lkml.kernel.org/r/YaodyZzu0MTCJcvO@elver.google.com Link: https://lkml.kernel.org/r/20220128105631.509772-1-elver@google.com Signed-off-by: Marco Elver Reviewed-by: Nathan Chancellor Reviewed-by: Kees Cook Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: Nathan Chancellor Cc: Nick Desaulniers Cc: Arnd Bergmann Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kcsan: Support WEAK_MEMORY with Clang where no objtool support exists

2021-12-10T00:42:28+00:00

Clang and GCC behave a little differently when it comes to the __no_sanitize_thread attribute, which has valid reasons, and depending on context either one could be right. Traditionally, user space ThreadSanitizer [1] still expects instrumented builtin atomics (to avoid false positives) and __tsan_func_{entry,exit} (to generate meaningful stack traces), even if the function has the attribute no_sanitize("thread"). [1] https://clang.llvm.org/docs/ThreadSanitizer.html#attribute-no-sanitize-thread GCC doesn't follow the same policy (for better or worse), and removes all kinds of instrumentation if no_sanitize is added. Arguably, since this may be a problem for user space ThreadSanitizer, we expect this may change in future. Since KCSAN != ThreadSanitizer, the likelihood of false positives even without barrier instrumentation everywhere, is much lower by design. At least for Clang, however, to fully remove all sanitizer instrumentation, we must add the disable_sanitizer_instrumentation attribute, which is available since Clang 14.0. Signed-off-by: Marco Elver Signed-off-by: Paul E. McKenney

kcsan: Add core support for a subset of weak memory modeling

2021-12-10T00:42:26+00:00

Add support for modeling a subset of weak memory, which will enable detection of a subset of data races due to missing memory barriers. KCSAN's approach to detecting missing memory barriers is based on modeling access reordering, and enabled if `CONFIG_KCSAN_WEAK_MEMORY=y`, which depends on `CONFIG_KCSAN_STRICT=y`. The feature can be enabled or disabled at boot and runtime via the `kcsan.weak_memory` boot parameter. Each memory access for which a watchpoint is set up, is also selected for simulated reordering within the scope of its function (at most 1 in-flight access). We are limited to modeling the effects of "buffering" (delaying the access), since the runtime cannot "prefetch" accesses (therefore no acquire modeling). Once an access has been selected for reordering, it is checked along every other access until the end of the function scope. If an appropriate memory barrier is encountered, the access will no longer be considered for reordering. When the result of a memory operation should be ordered by a barrier, KCSAN can then detect data races where the conflict only occurs as a result of a missing barrier due to reordering accesses. Suggested-by: Dmitry Vyukov Signed-off-by: Marco Elver Signed-off-by: Paul E. McKenney

kcsan: Make strict mode imply interruptible watchers

2021-07-20T20:49:44+00:00

If CONFIG_KCSAN_STRICT=y, select CONFIG_KCSAN_INTERRUPT_WATCHER as well. With interruptible watchers, we'll also report same-CPU data races; if we requested strict mode, we might as well show these, too. Suggested-by: Paul E. McKenney Signed-off-by: Marco Elver Signed-off-by: Paul E. McKenney