On 26.11.2021 15:28, Andrew Cooper wrote: > On 26/11/2021 14:21, Jan Beulich wrote: >> On 26.11.2021 13:33, Andrew Cooper wrote: >>> Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com> >> I understand there's not much to say here, but the title saying just >> "annotate" without any context as to the purpose of the annotation >> is too little information imo. I guess this then goes for many more >> titles in this series. > > I really couldn't think of anything useful to say. Lots of these > patches are entirely mechanical.
Them being mechanical is imo unrelated to having a subject which is halfway meaningful even if one looks at a shortlog in a couple of years time. All it would take to disambiguate the titles would look to be "...: Annotate fnptr targets for CET-IBT". Arguably this arch- specific feature may be a little odd to encounter in common code logs, but that's still better than being entirely unspecific about the purpose of the annotations. >>> --- a/xen/include/xen/hypercall.h >>> +++ b/xen/include/xen/hypercall.h >>> @@ -18,12 +18,12 @@ >>> #include <asm/hypercall.h> >>> #include <xsm/xsm.h> >>> >>> -extern long >>> +extern long cf_check >>> do_sched_op( >>> int cmd, >>> XEN_GUEST_HANDLE_PARAM(void) arg); >> What purpose does the attribute serve on a declaration? On the surface >> I would consider it meaningful only on definitions, like e.g. __init. > > Because GCC treats cf_check (and nocf_check) as part of the function > type. Simply getting it wrong will yield a "definition doesn't match > prototype" error. > > Furthermore, it needs to be visible across translation units so one TU > can spot (and complain at) creating a function pointer to a non-local > non-endbr'd function. Hmm, it might well be that way, but that's not what the doc (for 11.2) says. While suggesting things are along the lines of what you say for "nocf_check", for "cf_check" it really only talks about code generation: "The cf_check attribute on a function is used to inform the compiler that ENDBR instruction should be placed at the function entry when ‘-fcf-protection=branch’ is enabled." And even for "nocf_check" it talks about extra compile time checks only when the attribute is applied to a function pointer variable/field, not when applied to a function. Jan
