* Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote: > Hi Andrey, > > On Fri, Mar 2, 2018 at 8:44 PM, Andrey Konovalov <andreyknvl@xxxxxxxxxx> wrote: > > This patchset adds a new mode to KASAN, which is called KHWASAN (Kernel > > HardWare assisted Address SANitizer). There's still some work to do and > > there are a few TODOs in the code, so I'm publishing this as a RFC to > > collect some initial feedback. > > > > The plan is to implement HWASan [1] for the kernel with the incentive, > > that it's going to have comparable performance, but in the same time > > consume much less memory, trading that off for somewhat imprecise bug > > detection and being supported only for arm64. > > > > The overall idea of the approach used by KHWASAN is the following: > > > > 1. By using the Top Byte Ignore arm64 CPU feature, we can store pointer > > tags in the top byte of each kernel pointer. > > And for how long will this be OK? Firstly it's not for production kernels, it's a hardware accelerator for an intrusive debug feature, so it shouldn't really matter, right? Secondly, if the top byte is lost and the other 56 bits can still be used that gives a virtual memory space of up to 65,536 TB, which should be enough for a few years in the arm64 space, right? > Remembering: > - AmigaBasic, > - MacOS, > - Emacs, > - ... > They all tried to use the same trick, and did regret... > (AmigaBasic never survived this failure). The 64-bit address space is really a lot larger, and it's a debug-info feature in any case. Thanks, Ingo -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
