On Mon, Jul 27, 2020 at 01:21:44PM +0200, Ingo Molnar wrote: > > * [email protected] <[email protected]> wrote: > > > > > Abuse the SMAP rules to ensure poke_int3_handler() doesn't call out to > > anything. > > > > Signed-off-by: Peter Zijlstra (Intel) <[email protected]> > > --- > > tools/objtool/check.c | 8 ++++++++ > > 1 file changed, 8 insertions(+) > > > > --- a/tools/objtool/check.c > > +++ b/tools/objtool/check.c > > @@ -551,6 +551,14 @@ static const char *uaccess_safe_builtin[ > > "__memcpy_mcsafe", > > "mcsafe_handle_tail", > > "ftrace_likely_update", /* CONFIG_TRACE_BRANCH_PROFILING */ > > + /* > > + * Abuse alert! > > + * > > + * poke_int3_handler() is not in fact related to uaccess at all, we > > + * abuse the uaccess rules to ensure poke_int3_handler() is self > > + * contained and doesn't CALL out to other code. > > + */ > > + "poke_int3_handler", > > So ->uaccess_safe makes sure that we don't CALL into non-uaccess-safe > functions, but it still allows CALLs into *other* uaccess-safe > functions, right? > > So unless I missed something in the logic, the comment should say > something like "doesn't CALL out to other non-uaccess safe code" or > so? Which is, arguably, like 99% of all functions - but still, a whole > bunch are allowed, such as low level instrumentation and other utility > functions.
Right, so poke_int3_handler() is also noinstr and by that isn't allowed to call out into !noinstr code. The intersection should be small. But yeah, perhaps this is a bad idea and I should add another annotation for this,.. dunno.
