[PATCH v3 3/7] arm64/Kconfig: add LSUI Kconfig

[Yeoreum Yun]

Since Armv9.6, FEAT_LSUI supplies the load/store instructions for
previleged level to access to access user memory without clearing
PSTATE.PAN bit.
It's enough to add CONFIG_AS_HAS_LSUI only because the code for LUSI uses
indiviual `.arch_extension` entries.

Signed-off-by: Yeoreum Yun <yeoreum.yun at arm.com>
---
 arch/arm64/Kconfig | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 55fc331af337..769fbb507996 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -2237,6 +2237,15 @@ config ARM64_GCS
 
 endmenu # "v9.4 architectural features"
 
+config AS_HAS_LSUI
+	def_bool $(as-instr,.arch_extension lsui)
+	help
+	 Unprivileged Load Store is an extension to introduce unprivileged
+	 variants of load and store instructions so that clearing PSTATE.PAN
+	 is never required in privileged mode.
+	 This feature is available with clang version 20 and later and not yet
+	 supported by gcc.
+
 config ARM64_SVE
 	bool "ARM Scalable Vector Extension support"
 	default y
-- 
LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}