Hi Andrey,
On Tue, Jul 23, 2019 at 08:03:29PM +0200, Andrey Konovalov wrote:
On Tue, Jul 23, 2019 at 7:59 PM Andrey Konovalov andreyknvl@google.com wrote:
=== Overview
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.
Right now the kernel is already able to handle user faults with tagged pointers, due to these patches:
- 81cddd65 ("arm64: traps: fix userspace cache maintenance emulation on a tagged pointer")
- 7dcd9dd8 ("arm64: hw_breakpoint: fix watchpoint matching for tagged pointers")
- 276e9327 ("arm64: entry: improve data abort handling of tagged pointers")
This patchset extends tagged pointer support to syscall arguments.
[...]
Do you think this is ready to be merged?
Should this go through the mm or the arm tree?
I would certainly prefer to take at least the arm64 bits via the arm64 tree (i.e. patches 1, 2 and 15). We also need a Documentation patch describing the new ABI.
Will