diff --git a/Documentation/arm64/elf_hwcaps.rst b/Documentation/arm64/elf_hwcaps.rst
index 9ee7f8f..7fa3d21 100644
--- a/Documentation/arm64/elf_hwcaps.rst
+++ b/Documentation/arm64/elf_hwcaps.rst
@@ -155,6 +155,9 @@
 HWCAP_SSBS
     Functionality implied by ID_AA64PFR1_EL1.SSBS == 0b0010.
 
+HWCAP_SB
+    Functionality implied by ID_AA64ISAR1_EL1.SB == 0b0001.
+
 HWCAP_PACA
     Functionality implied by ID_AA64ISAR1_EL1.APA == 0b0001 or
     ID_AA64ISAR1_EL1.API == 0b0001, as described by