On 25 Nov 2015 at 10:13, Mathias Krause wrote: > I myself had some educating experience seeing my machine triple fault > when resuming from a S3 sleep. The root cause was a variable that was > annotated __read_only but that was (unnecessarily) modified during CPU > bring-up phase. Debugging that kind of problems is sort of a PITA, you > could imagine. actually the kernel could silently recover from this given how the page fault handler could easily determine that the fault address fell into the data..read_only section and just silently undo the read-only property, log the event to dmesg and retry the faulting access. > So, prior extending the usage of the __read_only annotation some > toolchain support is needed. Maybe a gcc plugin that'll warn/error on > code that writes to such a variable but is not __init itself. this is exactly what i suggested earlier in the constify thread ;). note that this will produce false positives because __init* annotations are not propagated everywhere they could be. > The initify and checker plugins from the PaX patch might be worth to > look at for that purpose, as they're doing similar things already. one of our plans for initify is to add the discovery and propagation of _init* annotations as well, it'd not only fix the false positives mentioned above but also help reduce the kernel size (code/data/rodata). -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
