On 3/16/21 10:12 AM, Yu, Yu-cheng wrote: > On 3/16/2021 8:49 AM, Dave Hansen wrote: ... >> Is "#ifdef __i386__" the right thing to use here? I guess ENDBR only >> ends up getting used in the VDSO, but there's a lot of >> non-userspace-exposed stuff in calling.h. It seems a bit weird to have >> the normally userspace-only __i386__ in there. >> >> I don't see any existing direct use of __i386__ in arch/x86/entry/vdso. > > Good point. My thought was, __i386__ comes from the compiler having the > -m32 command-line option, and it is not dependent on anything else. > > Alternatively, there is another compiler-defined macro _CET_ENDBR that > can be used. We can put the following in calling.h: > > #ifdef __CET__ > #include <cet.h> > #else > #define _CET_ENDBR > #endif > > and then use _CET_ENDBR in other files. How is that? > > In the future, in case we have kernel-mode IBT, ENDBR macros are also > needed for other assembly files. First of all, I think putting the macro in calling.h is wrong if it will be used exclusively in the VDSO. If it's VDSO-only, please put it in a local header in the vdso/ directory, maybe even a new cet.h. Also, Boris asked for two *different* macros for 32 and 64-bit: https://lore.kernel.org/linux-api/20210310231731.GK23521@xxxxxxx/ Could you do that in the next version, please?
