prctl: Introduce PR_MTE_STORE_ONLY

PR_MTE_STORE_ONLY is used to restrict the MTE tag check for store
opeartion only.

Signed-off-by: Yeoreum Yun <[email protected]>
Reviewed-by: Mark Brown <[email protected]>
Tested-by: Mark Brown <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Catalin Marinas <[email protected]>

Author: LeviYeoReum

include/uapi/linux/prctl.h

@@ -244,6 +244,8 @@ struct prctl_mm_map {
 # define PR_MTE_TAG_MASK		(0xffffUL << PR_MTE_TAG_SHIFT)
 /* Unused; kept only for source compatibility */
 # define PR_MTE_TCF_SHIFT		1
+/* MTE tag check store only */
+# define PR_MTE_STORE_ONLY		(1UL << 19)
 /* RISC-V pointer masking tag length */
 # define PR_PMLEN_SHIFT			24
 # define PR_PMLEN_MASK			(0x7fUL << PR_PMLEN_SHIFT)