On Wed, Apr 18, 2018 at 08:53:09PM +0200, Andrey Konovalov wrote: > Hi! > > arm64 has a feature called Top Byte Ignore, which allows to embed pointer > tags into the top byte of each pointer. Userspace programs (such as > HWASan, a memory debugging tool [1]) might use this feature and pass > tagged user pointers to the kernel through syscalls or other interfaces. > > This patch makes a few of the kernel interfaces accept tagged user > pointers. The kernel is already able to handle user faults with tagged > pointers and has the untagged_addr macro, which this patchset reuses. > > We're not trying to cover all possible ways the kernel accepts user > pointers in one patchset, so this one should be considered as a start. How many changes do you anticipate? This patchset looks small and reasonable, but I see a potential to become a boilerplate. Would we need to change every driver which implements ioctl() to strip these bits? -- Kirill A. Shutemov
