kselftest/arm64/mte: Add address tag related macro and function

Add address tag related macro and function to test MTE_FAR feature.

Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20250618084513.1761345-8-yeoreum.yun@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Author: LeviYeoReum

tools/testing/selftests/arm64/mte/mte_common_util.c

@@ -6,6 +6,7 @@
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <time.h>
 #include <unistd.h>
 
 #include <linux/auxvec.h>
@@ -130,6 +131,19 @@ void mte_clear_tags(void *ptr, size_t size)
 	mte_clear_tag_address_range(ptr, size);
 }
 
+void *mte_insert_atag(void *ptr)
+{
+	unsigned char atag;
+
+	atag =  mtefar_support ? (random() % MT_ATAG_MASK) + 1 : 0;
+	return (void *)MT_SET_ATAG((unsigned long)ptr, atag);
+}
+
+void *mte_clear_atag(void *ptr)
+{
+	return (void *)MT_CLEAR_ATAG((unsigned long)ptr);
+}
+
 static void *__mte_allocate_memory_range(size_t size, int mem_type, int mapping,
 					 size_t range_before, size_t range_after,
 					 bool tags, int fd)
@@ -330,6 +344,9 @@ int mte_default_setup(void)
 	unsigned long en = 0;
 	int ret;
 
+	/* To generate random address tag */
+	srandom(time(NULL));
+
 	if (!(hwcaps2 & HWCAP2_MTE))
 		ksft_exit_skip("MTE features unavailable\n");
 

tools/testing/selftests/arm64/mte/mte_common_util.h

@@ -56,6 +56,8 @@ void mte_free_memory_tag_range(void *ptr, size_t size, int mem_type,
 			       size_t range_before, size_t range_after);
 void *mte_insert_tags(void *ptr, size_t size);
 void mte_clear_tags(void *ptr, size_t size);
+void *mte_insert_atag(void *ptr);
+void *mte_clear_atag(void *ptr);
 int mte_default_setup(void);
 void mte_restore_setup(void);
 int mte_switch_mode(int mte_option, unsigned long incl_mask);

tools/testing/selftests/arm64/mte/mte_def.h

@@ -42,13 +42,21 @@
 #define MT_TAG_COUNT		16
 #define MT_INCLUDE_TAG_MASK	0xFFFF
 #define MT_EXCLUDE_TAG_MASK	0x0
+#define MT_ATAG_SHIFT		60
+#define MT_ATAG_MASK		0xFUL
 
 #define MT_ALIGN_GRANULE	(MT_GRANULE_SIZE - 1)
 #define MT_CLEAR_TAG(x)		((x) & ~(MT_TAG_MASK << MT_TAG_SHIFT))
 #define MT_SET_TAG(x, y)	((x) | (y << MT_TAG_SHIFT))
 #define MT_FETCH_TAG(x)		((x >> MT_TAG_SHIFT) & (MT_TAG_MASK))
 #define MT_ALIGN_UP(x)		((x + MT_ALIGN_GRANULE) & ~(MT_ALIGN_GRANULE))
 
+#define MT_CLEAR_ATAG(x)	((x) & ~(MT_TAG_MASK << MT_ATAG_SHIFT))
+#define MT_SET_ATAG(x, y)	((x) | (((y) & MT_ATAG_MASK) << MT_ATAG_SHIFT))
+#define MT_FETCH_ATAG(x)	((x >> MT_ATAG_SHIFT) & (MT_ATAG_MASK))
+
+#define MT_CLEAR_TAGS(x) 	(MT_CLEAR_ATAG(MT_CLEAR_TAG(x)))
+
 #define MT_PSTATE_TCO_SHIFT	25
 #define MT_PSTATE_TCO_MASK	~(0x1 << MT_PSTATE_TCO_SHIFT)
 #define MT_PSTATE_TCO_EN	1