On Mon, Aug 31, 2015 at 8:55 PM, Brian Gerst <brge...@gmail.com> wrote: > On Mon, Aug 31, 2015 at 6:01 PM, Andy Lutomirski <l...@amacapital.net> wrote: >> On Mon, Aug 31, 2015 at 2:47 PM, Brian Gerst <brge...@gmail.com> wrote: >>> On Mon, Aug 31, 2015 at 5:00 PM, Andy Lutomirski <l...@amacapital.net> >>> wrote: >>>> Why not just a struct? Also, why is this all tangled up in gsbase >>>> initialization? >>> >>> It has to do with the fact that the GCC stackprotector is hardcoded to >>> look for the canary at %gs:40. Since we also use %gs for the percpu >>> segment, we have to make sure that the canary is placed at the start >>> of the percpu section. Overlaying it onto the bottom of the IRQ stack >>> and was the most convenient way to do it, with a side benefit that >>> overflowing the stack will trip the canary. >> >> Would a struct not make more sense, then? > > Why would it? A union shows the overlay better.
I guess you're thinking of it as an overlay and I'm thinking of it as the layout being the IRQ stack directly above the stack canary. --Andy > > -- > Brian Gerst -- Andy Lutomirski AMA Capital Management, LLC -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
