On Thu, Aug 30, 2018 at 1:41 PM, Andrey Konovalov <andreyknvl@xxxxxxxxxx> wrote: > 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. > > Thanks! > > [1] http://clang.llvm.org/docs/HardwareAssistedAddressSanitizerDesign.html > > Changes in v6: > - Added annotations for user pointer casts found by sparse. Hi Catalin, I've added annotations for the user pointer casts pointed by the new sparse flag -Wcast-from-as as you asked. I've used __force casts instead of adding specialized macros. There are also non annotated casts for other pointer types (iomem, rcu) which are detected with the new flag, should I annotate those as well? I'm not sure though what value would that bring though, as there are ~3000 various sparse warnings produced with the default flags anyway. WDYT? Thanks! [1] https://github.com/lucvoo/sparse-dev/commit/5f960cb10f56ec2017c128ef9d16060e0145f292
