On Thu, May 14, 2020 at 02:51:32PM +0200, Thomas Gleixner wrote: > Peter Zijlstra <[email protected]> writes: > > On Wed, May 13, 2020 at 09:57:52PM -0700, Andy Lutomirski wrote: > >> On Tue, May 5, 2020 at 7:15 AM Thomas Gleixner <[email protected]> wrote: > >> > > >> > From: Peter Zijlstra <[email protected]> > >> > > >> > Use arch_atomic_*() and READ_ONCE_NOCHECK() to ensure nothing untoward > >> > creeps in and ruins things. > >> > > >> > That is; this is the INT3 text poke handler, strictly limit the code > >> > that runs in it, lest it inadvertenly hits yet another INT3. > >> > >> > >> Acked-by: Andy Lutomirski <[email protected]> > >> > >> Does objtool catch this error? > > > > It does not. I'll put it on the (endless) todo list.. > > Well, at least it detects when that code calls out into something which > is not in the non-instrumentable section.
True, but the more specific problem is that noinstr code can use jump_label/static_call just fine. So a more specific test is validating none of that happens in the INT3 handler before poke_int3_handler(). Which is what I think Andy was after.
