On 8/1/19 5:38 AM, Kevin Brodsky wrote: > This patch series only changes what is allowed or not at the syscall > interface. It does not change the address space size. On arm64, TBI (Top > Byte Ignore) has always been enabled for userspace, so it has never been > possible to use the upper 8 bits of user pointers for addressing. Oh, so does the address space that's available already chop that out? > If other architectures were to support a similar functionality, then I > agree that a common and more generic interface (if needed) would be > helpful, but as it stands this is an arm64-specific prctl, and on arm64 > the address tag is defined by the architecture as bits [63:56]. It should then be an arch_prctl(), no?