On Thu, Mar 3, 2016 at 6:40 PM, Mark Rutland <mark.rutland@xxxxxxx> wrote: > Hi, > > On Thu, Mar 03, 2016 at 06:17:31PM +0100, Alexander Potapenko wrote: >> Please replace "ASAN" with "KASAN". >> >> On Thu, Mar 3, 2016 at 5:54 PM, Mark Rutland <mark.rutland@xxxxxxx> wrote: >> > Functions which the compiler has instrumented for ASAN place poison on >> > the stack shadow upon entry and remove this poison prior to returning. >> > >> > In some cases (e.g. hotplug and idle), CPUs may exit the kernel a number >> > of levels deep in C code. If there are any instrumented functions on >> > this critical path, these will leave portions of the idle thread stack >> > shadow poisoned. >> > >> > If a CPU returns to the kernel via a different path (e.g. a cold entry), >> > then depending on stack frame layout subsequent calls to instrumented >> > functions may use regions of the stack with stale poison, resulting in >> > (spurious) KASAN splats to the console. >> > >> > Contemporary GCCs always add stack shadow poisoning when ASAN is >> > enabled, even when asked to not instrument a function [1], so we can't >> > simply annotate functions on the critical path to avoid poisoning. >> > >> > Instead, this series explicitly removes any stale poison before it can >> > be hit. In the common hotplug case we clear the entire stack shadow in >> > common code, before a CPU is brought online. >> > >> > On architectures which perform a cold return as part of cpu idle may >> > retain an architecture-specific amount of stack contents. To retain the >> > poison for this retained context, the arch code must call the core KASAN >> > code, passing a "watermark" stack pointer value beyond which shadow will >> > be cleared. Architectures which don't perform a cold return as part of >> > idle do not need any additional code. > > For the above, and the rest of the series, ASAN consistently refers to > the compiler AddressSanitizer feature, and KASAN consistently refers to > the Linux-specific infrastructure. A simple s/[^K]ASAN/KASAN/ would > arguably be wrong (e.g. when referring to GCC behaviour above). I don't think there's been any convention about the compiler feature name, we usually talked about ASan as a userspace tool and KASAN as a kernel-space one, although they share the compiler part. > If there is a this needs rework, then I'm happy to s/[^K]ASAN/ASan/ to > follow the usual ASan naming convention and avoid confusion. Otherwise, > spinning a v3 is simply churn. I don't insist on changing this, I should've chimed in before. Feel free to retain the above patch description. > Thanks, > Mark. -- Alexander Potapenko Software Engineer Google Germany GmbH Erika-Mann-Straße, 33 80636 München Geschäftsführer: Matthew Scott Sucherman, Paul Terence Manicle Registergericht und -nummer: Hamburg, HRB 86891 Sitz der Gesellschaft: Hamburg Diese E-Mail ist vertraulich. Wenn Sie nicht der richtige Adressat sind, leiten Sie diese bitte nicht weiter, informieren Sie den Absender und löschen Sie die E-Mail und alle Anhänge. Vielen Dank. This e-mail is confidential. If you are not the right addressee please do not forward it, please inform the sender, and please erase this e-mail including any attachments. Thanks. -- 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
