On 12/18/2017 12:39 PM, Sandra Loosemore wrote: > On 12/17/2017 05:05 PM, Tsimbalist, Igor V wrote: >> -fcf-protection -mcet is incompatible with makecontext family functions >> since they can't properly set up and destroy shadow stack pointer. This >> change provides a mechanism to help detection shadow stack compatibility. >> The current proposal is to add -mcheck-shstk-compat option which will >> predefine __CHECK_SHSTK_COMPAT__ macro. The option will be >> set on by default. Then we can add a code >> >> #if defined __SHSTK__ && defined __CHECK_SHSTK_COMPAT__ >> # error This source is incompatible with -mshstk >> #endif >> >> to <ucontext.h>. > > The functional change here is out of my maintainership domain, but.... > Why does this need a new macro and a new option to control it? If the > code being protected doesn't work properly with -mshstk, it seems like > it would be more robust to do just > > #if defined __SHSTK__ > # error This source is incompatible with -mshstk > #endif > > I don't see any discussion in the bugzilla issue to explain this. I'd tend to agree. Making another option to handle this seems excessive.
jeff
