Miguel Ojeda wrote on Fri, Aug 31, 2018: > Instead of using version checks per-compiler to define (or not) > each attribute, use __has_attribute to test for them, following > the cleanup started with commit 815f0ddb346c > ("include/linux/compiler*.h: make compiler-*.h mutually exclusive"). > > All the attributes that are fairly common/standard (i.e. those that > do not require extra logic to define them) have been moved > to a new file include/linux/compiler_attributes.h. > > In an effort to make the file as regular as possible, comments > stating the purpose of attributes have been removed. Instead, > links to the compiler docs have been added (i.e. to gcc and, > if available, to clang as well). In addition, they have been sorted. > > Finally, if an attribute is optional (i.e. if it is guarded > by __has_attribute), the reason has been stated for future reference. > > Cc: Eli Friedman <efrie...@codeaurora.org> > Cc: Christopher Li <spa...@chrisli.org> > Cc: Kees Cook <keesc...@chromium.org> > Cc: Ingo Molnar <mi...@kernel.org> > Cc: Geert Uytterhoeven <ge...@linux-m68k.org> > Cc: Arnd Bergmann <a...@arndb.de> > Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org> > Cc: Masahiro Yamada <yamada.masah...@socionext.com> > Cc: Joe Perches <j...@perches.com> > Cc: Dominique Martinet <asmad...@codewreck.org> > Cc: Nick Desaulniers <ndesaulni...@google.com> > Cc: Linus Torvalds <torva...@linux-foundation.org> > Signed-off-by: Miguel Ojeda <miguel.ojeda.sando...@gmail.com>
Nice work! Since I'm being Cc'd I took the time to test this as well, and have no problem with libbcc-building-with-clang (or native x86 gcc build) Nick already made many comments so I only have one more. > [...] > diff --git a/include/linux/compiler_attributes.h > b/include/linux/compiler_attributes.h > new file mode 100644 > index 000000000000..a9dfafc8fd19 > --- /dev/null > +++ b/include/linux/compiler_attributes.h > [...] > +/* > + * To check for optional attributes, we use __has_attribute, which is > supported > + * on gcc >= 5, clang >= 2.9 and icc >= 17. In the meantime, to support > + * 4.6 <= gcc < 5, we implement __has_attribute by hand. > + */ > +#ifndef __has_attribute > +#define __has_attribute(x) __GCC4_has_attribute_##x > +#define __GCC4_has_attribute_externally_visible 1 > +#define __GCC4_has_attribute_noclone 1 > +#define __GCC4_has_attribute_optimize 1 > +#if __GNUC_MINOR__ >= 8 > +#define __GCC4_has_attribute_no_sanitize_address 1 > +#endif > +#if __GNUC_MINOR__ >= 9 > +#define __GCC4_has_attribute_assume_aligned 1 > +#endif > +#endif Hmm, if this is in this file and not compiler-gcc, I am not sure about using GNUC_MINOR without checking the major -- I have no idea what kind of versions e.g. icc will use (or what attributes ancients version of clang or old icc support, actually) It's a bit of research work but I think it'd be cleaner to define similar macros for all three compilers, if we care about the old versions... Or actually.. For clang you've implicitely required clang >= 3.0 in patch 3 of this serie, so presumabely it wouldn't need this compat macro at all. For icc I think icc 17 is still fairly recent... But I just abused work to test and linux fails to compile with icc 15/17/18 for other reasons (unrelated to this patch), so unless anyone helps with this I'm tempted to suggest leaving it at it, and whoever that is will probably have a better idea of how far back they want to make icc work / what attributes are defined there. It's a bit of a shame there's no linux-compilers list to reach out to :) (this would need to move the include of this file after the compiler-specific headers, but from what I can see there is no problem with that) -- Dominique