On Mon, Sep 26, 2022, at 11:07 PM, Kees Cook wrote: > On Mon, Sep 26, 2022 at 01:17:18PM -0700, Nick Desaulniers wrote: >> + Arnd >> >> On Mon, Sep 26, 2022 at 12:11 PM Kees Cook <keescook@xxxxxxxxxxxx> wrote: >> > --- >> > v2: >> > - fix comment typo >> > - wrap clang pragma to avoid GCC warnings >> > - style nit cleanups >> > - rename __castable_to_type() to castable_to_type() >> > - remove prior overflows_type() definition >> > v1: https://lore.kernel.org/lkml/20220926003743.409911-1-keescook@xxxxxxxxxxxx >> > diff --git a/lib/overflow_kunit.c b/lib/overflow_kunit.c >> > index f385ca652b74..fffc3f86181d 100644 >> > --- a/lib/overflow_kunit.c >> > +++ b/lib/overflow_kunit.c >> > @@ -16,6 +16,11 @@ >> > #include <linux/types.h> >> > #include <linux/vmalloc.h> >> > >> > +/* We're expecting to do a lot of "always true" or "always false" tests. */ >> > +#ifdef CONFIG_CC_IS_CLANG >> > +#pragma clang diagnostic ignored "-Wtautological-constant-out-of-range-compare" >> > +#endif >> >> Any chance we can reuse parts of __diag_ignore or __diag_clang from >> include/linux/compiler_types.h or include/linux/compiler-clang.h >> respectively? > > Hm, I'm not sure how those are supposed to be used. Those defines don't > seem to be used externally? We use them in a couple of places. When I originally introduced them, the idea was to add more infrastructure around these to replace the various -Wno-... flags in local makefiles with more targetted annotations, and then have a way to control the warning levels (W=1 W=2 E=1 etc) per directory and per file, but I never completed the work to add the interesting bits. >> Those are needed for pragmas within preprocessor macros, which we >> don't have here, but I suspect they may be more concise to use here. > > Yeah, I was surprised when I had to wrap it in #ifdef given "clang" is > part of the string. > >> >> > +#define TEST_SAME_TYPE(t1, t2, same) do { \ >> > + typeof(t1) __t1h = type_max(t1); \ >> > + typeof(t1) __t1l = type_min(t1); \ >> > + typeof(t2) __t2h = type_max(t2); \ >> > + typeof(t2) __t2l = type_min(t2); \ >> >> Can we use __auto_type here rather than typeof(macro expansion)? > > I'd rather it stay explicit -- otherwise we start to wander into "oops, > we got lucky" territory for what should be a really distinct test case. The idea of __auto_type is to avoid the more deeply nested macros. If the preprocessed file turns into an absolute mess, adding a temporary variable may help. Not sure if that applies here. Arnd
