arm64/sme: Provide storage for ZT0
When the system supports SME2 there is an additional register ZT0 which
we must store when the task is using SME. Since ZT0 is accessible only
when PSTATE.ZA is set just like ZA we allocate storage for it along with
ZA, increasing the allocation size for the memory region where we store
ZA and storing the data for ZT after that for ZA.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20221208-arm64-sme2-v4-9-f2fa0aef982f@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 4ce0c43..71d59b5 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -307,11 +307,11 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
/*
* In the unlikely event that we create a new thread with ZA
- * enabled we should retain the ZA state so duplicate it here.
- * This may be shortly freed if we exec() or if CLONE_SETTLS
- * but it's simpler to do it here. To avoid confusing the rest
- * of the code ensure that we have a sve_state allocated
- * whenever sme_state is allocated.
+ * enabled we should retain the ZA and ZT state so duplicate
+ * it here. This may be shortly freed if we exec() or if
+ * CLONE_SETTLS but it's simpler to do it here. To avoid
+ * confusing the rest of the code ensure that we have a
+ * sve_state allocated whenever sme_state is allocated.
*/
if (thread_za_enabled(&src->thread)) {
dst->thread.sve_state = kzalloc(sve_state_size(src),
