Index: configure.ac
--- configure.ac.orig
+++ configure.ac
@@ -1078,6 +1078,54 @@ if test "$nettle_cv_asm_x86_gnu_property" = yes; then
 	.popsection'
 fi
 
+dnl  Define
+dnl  1. ASM_X86_ENDBR for bti.
+dnl  2. ASM_X86_MARK_CET to add a .note.gnu.property section to mark
+dnl  Arm BTI support if needed.
+AC_CACHE_CHECK([if Arm BTI is enabled],
+  [nettle_cv_asm_arm_bti],
+  [AC_TRY_COMPILE([
+#ifndef __ARM_FEATURE_BTI_DEFAULT
+#error Arm BTI is not enabled
+#endif
+  ], [],
+  [nettle_cv_asm_arm_bti=yes],
+  [nettle_cv_asm_arm_bti=no])])
+if test "$nettle_cv_asm_arm_bti" = yes; then
+  ASM_X86_ENDBR="bti c"
+  AC_CACHE_CHECK([if .note.gnu.property section is needed],
+    [nettle_cv_asm_arm_gnu_property],
+    [AC_TRY_COMPILE([
+#if !defined __ELF__ || !defined __ARM_FEATURE_BTI_DEFAULT
+#error GNU property is not needed
+#endif
+    ], [],
+    [nettle_cv_asm_arm_gnu_property=yes],
+    [nettle_cv_asm_arm_gnu_property=no])])
+else
+  nettle_cv_asm_arm_gnu_property=no
+fi
+if test "$nettle_cv_asm_arm_gnu_property" = yes; then
+  ASM_X86_MARK_CET='
+	.pushsection ".note.gnu.property", "a"
+	.p2align 3
+	.long 1f - 0f
+	.long 4f - 1f
+	.long 5
+0:
+	.asciz "GNU"
+1:
+	.p2align 3
+	.long 0xc0000000
+	.long 3f - 2f
+2:
+	.long 1
+3:
+	.p2align 3
+4:
+	.popsection'
+fi
+
 AC_SUBST(ASM_SYMBOL_PREFIX)
 AC_SUBST(ASM_ELF_STYLE)
 AC_SUBST(ASM_COFF_STYLE)