Messages in this thread | | | From | Marco Elver <> | Date | Tue, 2 Jun 2020 21:25:47 +0200 | Subject | Re: [PATCH -tip 1/2] Kconfig: Bump required compiler version of KASAN and UBSAN |
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On Tue, 2 Jun 2020 at 21:19, Peter Zijlstra <peterz@infradead.org> wrote: > > On Tue, Jun 02, 2020 at 11:57:15AM -0700, Nick Desaulniers wrote: > > On Tue, Jun 2, 2020 at 11:44 AM 'Marco Elver' via Clang Built Linux > > <clang-built-linux@googlegroups.com> wrote: > > > > > > Adds config variable CC_HAS_WORKING_NOSANITIZE, which will be true if we > > > have a compiler that does not fail builds due to no_sanitize functions. > > > This does not yet mean they work as intended, but for automated > > > build-tests, this is the minimum requirement. > > > > > > For example, we require that __always_inline functions used from > > > no_sanitize functions do not generate instrumentation. On GCC <= 7 this > > > fails to build entirely, therefore we make the minimum version GCC 8. > > > > > > For KCSAN this is a non-functional change, however, we should add it in > > > case this variable changes in future. > > > > > > Link: https://lkml.kernel.org/r/20200602175859.GC2604@hirez.programming.kicks-ass.net > > > Suggested-by: Peter Zijlstra <peterz@infradead.org> > > > Signed-off-by: Marco Elver <elver@google.com> > > > > Is this a problem only for x86? If so, that's quite a jump in minimal > > compiler versions for a feature that I don't think is currently > > problematic for other architectures? (Based on > > https://lore.kernel.org/lkml/20200529171104.GD706518@hirez.programming.kicks-ass.net/ > > ) > > Currently x86 only, but I know other arch maintainers are planning to > have a hard look at their code based on our findings.
I've already spotted a bunch of 'noinstr' outside arch/x86 e.g. in kernel/{locking,rcu}, and a bunch of these functions use atomic_*, all of which are __always_inline. The noinstr uses outside arch/x86 would break builds on all architecture with GCC <= 7 when using sanitizers. At least that's what led me to conclude we need this for all architectures.
Thanks, -- Marco
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