diff --git a/Documentation/riscv/uabi.rst b/Documentation/riscv/uabi.rst
index 21a82cfb6c4dd..2ebec4c522308 100644
--- a/Documentation/riscv/uabi.rst
+++ b/Documentation/riscv/uabi.rst
@@ -3,4 +3,46 @@
 RISC-V Linux User ABI
 =====================
 
+ISA string ordering in /proc/cpuinfo
+------------------------------------
+
+The canonical order of ISA extension names in the ISA string is defined in
+chapter 27 of the unprivileged specification.
+The specification uses vague wording, such as should, when it comes to ordering,
+so for our purposes the following rules apply:
+
+#. Single-letter extensions come first, in canonical order.
+   The canonical order is "IMAFDQLCBKJTPVH".
+
+#. All multi-letter extensions will be separated from other extensions by an
+   underscore.
+
+#. Additional standard extensions (starting with 'Z') will be sorted after
+   single-letter extensions and before any higher-privileged extensions.
+
+#. For additional standard extensions, the first letter following the 'Z'
+  conventionally indicates the most closely related alphabetical
+  extension category. If multiple 'Z' extensions are named, they will be ordered
+  first by category, in canonical order, as listed above, then alphabetically
+  within a category.
+
+#. Standard supervisor-level extensions (starting with 'S') will be listed
+   after standard unprivileged extensions.  If multiple supervisor-level
+   extensions are listed, they will be ordered alphabetically.
+
+#. Standard machine-level extensions (starting with 'Zxm') will be listed
+   after any lower-privileged, standard extensions. If multiple machine-level
+   extensions are listed, they will be ordered alphabetically.
+
+#. Non-standard extensions (starting with 'X') will be listed after all standard
+   extensions. If multiple non-standard extensions are listed, they will be
+   ordered alphabetically.
+
+An example string following the order is::
+
+   rv64imadc_zifoo_zigoo_zafoo_sbar_scar_zxmbaz_xqux_xrux
+
+Misaligned accesses
+-------------------
+
 Misaligned accesses are supported in userspace, but they may perform poorly.
diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
index 86328e3acb02e..57439da71c775 100644
--- a/arch/riscv/include/asm/hwcap.h
+++ b/arch/riscv/include/asm/hwcap.h
@@ -51,14 +51,15 @@ extern unsigned long elf_hwcap;
  * RISCV_ISA_EXT_MAX. 0-25 range is reserved for single letter
  * extensions while all the multi-letter extensions should define the next
  * available logical extension id.
+ * Entries are sorted alphabetically.
  */
 enum riscv_isa_ext_id {
 	RISCV_ISA_EXT_SSCOFPMF = RISCV_ISA_EXT_BASE,
+	RISCV_ISA_EXT_SSTC,
+	RISCV_ISA_EXT_SVINVAL,
 	RISCV_ISA_EXT_SVPBMT,
 	RISCV_ISA_EXT_ZICBOM,
 	RISCV_ISA_EXT_ZIHINTPAUSE,
-	RISCV_ISA_EXT_SSTC,
-	RISCV_ISA_EXT_SVINVAL,
 	RISCV_ISA_EXT_ID_MAX
 };
 static_assert(RISCV_ISA_EXT_ID_MAX <= RISCV_ISA_EXT_MAX);
@@ -67,11 +68,12 @@ static_assert(RISCV_ISA_EXT_ID_MAX <= RISCV_ISA_EXT_MAX);
  * This enum represents the logical ID for each RISC-V ISA extension static
  * keys. We can use static key to optimize code path if some ISA extensions
  * are available.
+ * Entries are sorted alphabetically.
  */
 enum riscv_isa_ext_key {
 	RISCV_ISA_EXT_KEY_FPU,		/* For 'F' and 'D' */
-	RISCV_ISA_EXT_KEY_ZIHINTPAUSE,
 	RISCV_ISA_EXT_KEY_SVINVAL,
+	RISCV_ISA_EXT_KEY_ZIHINTPAUSE,
 	RISCV_ISA_EXT_KEY_MAX,
 };
 
@@ -91,10 +93,10 @@ static __always_inline int riscv_isa_ext2key(int num)
 		return RISCV_ISA_EXT_KEY_FPU;
 	case RISCV_ISA_EXT_d:
 		return RISCV_ISA_EXT_KEY_FPU;
-	case RISCV_ISA_EXT_ZIHINTPAUSE:
-		return RISCV_ISA_EXT_KEY_ZIHINTPAUSE;
 	case RISCV_ISA_EXT_SVINVAL:
 		return RISCV_ISA_EXT_KEY_SVINVAL;
+	case RISCV_ISA_EXT_ZIHINTPAUSE:
+		return RISCV_ISA_EXT_KEY_ZIHINTPAUSE;
 	default:
 		return -EINVAL;
 	}
diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
index 1b9a5a66e55ab..0bf1c7f663fc6 100644
--- a/arch/riscv/kernel/cpu.c
+++ b/arch/riscv/kernel/cpu.c
@@ -144,30 +144,53 @@ arch_initcall(riscv_cpuinfo_init);
 		.uprop = #UPROP,				\
 		.isa_ext_id = EXTID,				\
 	}
+
 /*
- * Here are the ordering rules of extension naming defined by RISC-V
- * specification :
- * 1. All extensions should be separated from other multi-letter extensions
- *    by an underscore.
- * 2. The first letter following the 'Z' conventionally indicates the most
+ * The canonical order of ISA extension names in the ISA string is defined in
+ * chapter 27 of the unprivileged specification.
+ *
+ * Ordinarily, for in-kernel data structures, this order is unimportant but
+ * isa_ext_arr defines the order of the ISA string in /proc/cpuinfo.
+ *
+ * The specification uses vague wording, such as should, when it comes to
+ * ordering, so for our purposes the following rules apply:
+ *
+ * 1. All multi-letter extensions must be separated from other extensions by an
+ *    underscore.
+ *
+ * 2. Additional standard extensions (starting with 'Z') must be sorted after
+ *    single-letter extensions and before any higher-privileged extensions.
+
+ * 3. The first letter following the 'Z' conventionally indicates the most
  *    closely related alphabetical extension category, IMAFDQLCBKJTPVH.
- *    If multiple 'Z' extensions are named, they should be ordered first
- *    by category, then alphabetically within a category.
- * 3. Standard supervisor-level extensions (starts with 'S') should be
- *    listed after standard unprivileged extensions.  If multiple
- *    supervisor-level extensions are listed, they should be ordered
+ *    If multiple 'Z' extensions are named, they must be ordered first by
+ *    category, then alphabetically within a category.
+ *
+ * 3. Standard supervisor-level extensions (starting with 'S') must be listed
+ *    after standard unprivileged extensions.  If multiple supervisor-level
+ *    extensions are listed, they must be ordered alphabetically.
+ *
+ * 4. Standard machine-level extensions (starting with 'Zxm') must be listed
+ *    after any lower-privileged, standard extensions.  If multiple
+ *    machine-level extensions are listed, they must be ordered
  *    alphabetically.
- * 4. Non-standard extensions (starts with 'X') must be listed after all
- *    standard extensions. They must be separated from other multi-letter
- *    extensions by an underscore.
+ *
+ * 5. Non-standard extensions (starting with 'X') must be listed after all
+ *    standard extensions. If multiple non-standard extensions are listed, they
+ *    must be ordered alphabetically.
+ *
+ * An example string following the order is:
+ *    rv64imadc_zifoo_zigoo_zafoo_sbar_scar_zxmbaz_xqux_xrux
+ *
+ * New entries to this struct should follow the ordering rules described above.
  */
 static struct riscv_isa_ext_data isa_ext_arr[] = {
+	__RISCV_ISA_EXT_DATA(zicbom, RISCV_ISA_EXT_ZICBOM),
+	__RISCV_ISA_EXT_DATA(zihintpause, RISCV_ISA_EXT_ZIHINTPAUSE),
 	__RISCV_ISA_EXT_DATA(sscofpmf, RISCV_ISA_EXT_SSCOFPMF),
 	__RISCV_ISA_EXT_DATA(sstc, RISCV_ISA_EXT_SSTC),
 	__RISCV_ISA_EXT_DATA(svinval, RISCV_ISA_EXT_SVINVAL),
 	__RISCV_ISA_EXT_DATA(svpbmt, RISCV_ISA_EXT_SVPBMT),
-	__RISCV_ISA_EXT_DATA(zicbom, RISCV_ISA_EXT_ZICBOM),
-	__RISCV_ISA_EXT_DATA(zihintpause, RISCV_ISA_EXT_ZIHINTPAUSE),
 	__RISCV_ISA_EXT_DATA("", RISCV_ISA_EXT_MAX),
 };
 
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 205bbd6b1fce0..dde0e91d76688 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -222,12 +222,13 @@ void __init riscv_fill_hwcap(void)
 					set_bit(nr, this_isa);
 				}
 			} else {
+				/* sorted alphabetically */
 				SET_ISA_EXT_MAP("sscofpmf", RISCV_ISA_EXT_SSCOFPMF);
+				SET_ISA_EXT_MAP("sstc", RISCV_ISA_EXT_SSTC);
+				SET_ISA_EXT_MAP("svinval", RISCV_ISA_EXT_SVINVAL);
 				SET_ISA_EXT_MAP("svpbmt", RISCV_ISA_EXT_SVPBMT);
 				SET_ISA_EXT_MAP("zicbom", RISCV_ISA_EXT_ZICBOM);
 				SET_ISA_EXT_MAP("zihintpause", RISCV_ISA_EXT_ZIHINTPAUSE);
-				SET_ISA_EXT_MAP("sstc", RISCV_ISA_EXT_SSTC);
-				SET_ISA_EXT_MAP("svinval", RISCV_ISA_EXT_SVINVAL);
 			}
 #undef SET_ISA_EXT_MAP
 		}
@@ -307,6 +308,7 @@ static bool __init_or_module cpufeature_probe_zicbom(unsigned int stage)
  * This code may also be executed before kernel relocation, so we cannot use
  * addresses generated by the address-of operator as they won't be valid in
  * this context.
+ * Tests, unless otherwise required, are to be added in alphabetical order.
  */
 static u32 __init_or_module cpufeature_probe(unsigned int stage)
 {