On Thu, Aug 22, 2024 at 02:15:23AM +0100, Mark Brown wrote: > There are two registers controlling the GCS state of EL0, GCSPR_EL0 which > is the current GCS pointer and GCSCRE0_EL1 which has enable bits for the > specific GCS functionality enabled for EL0. Manage these on context switch > and process lifetime events, GCS is reset on exec(). Also ensure that > any changes to the GCS memory are visible to other PEs and that changes > from other PEs are visible on this one by issuing a GCSB DSYNC when > moving to or from a thread with GCS. > > Since the current GCS configuration of a thread will be visible to > userspace we store the configuration in the format used with userspace > and provide a helper which configures the system register as needed. > > On systems that support GCS we always allow access to GCSPR_EL0, this > facilitates reporting of GCS faults if userspace implements disabling of > GCS on error - the GCS can still be discovered and examined even if GCS > has been disabled. > > Signed-off-by: Mark Brown <broonie@xxxxxxxxxx> We could do with a bit more code comments around GCSB DSYNC but otherwise it looks fine now. Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
