kselftest/arm64/mte: Check MTE_FAR feature is supported

To run the MTE_FAR test when cpu supports MTE_FAR feature,
check the MTE_FAR feature is supported in mte test.

Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20250618084513.1761345-7-yeoreum.yun@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Author: LeviYeoReum

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

@@ -26,6 +26,7 @@
 #define INIT_BUFFER_SIZE       256
 
 struct mte_fault_cxt cur_mte_cxt;
+bool mtefar_support;
 static unsigned int mte_cur_mode;
 static unsigned int mte_cur_pstate_tco;
 
@@ -325,12 +326,15 @@ int mte_switch_mode(int mte_option, unsigned long incl_mask)
 int mte_default_setup(void)
 {
 	unsigned long hwcaps2 = getauxval(AT_HWCAP2);
+	unsigned long hwcaps3 = getauxval(AT_HWCAP3);
 	unsigned long en = 0;
 	int ret;
 
 	if (!(hwcaps2 & HWCAP2_MTE))
 		ksft_exit_skip("MTE features unavailable\n");
 
+	mtefar_support = !!(hwcaps3 & HWCAP3_MTE_FAR);
+
 	/* Get current mte mode */
 	ret = prctl(PR_GET_TAGGED_ADDR_CTRL, en, 0, 0, 0);
 	if (ret < 0) {

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

@@ -37,6 +37,7 @@ struct mte_fault_cxt {
 };
 
 extern struct mte_fault_cxt cur_mte_cxt;
+extern bool mtefar_support;
 
 /* MTE utility functions */
 void mte_default_handler(int signum, siginfo_t *si, void *uc);