1 files changed, 29 insertions, 0 deletions
diff --git a/clang/docs/AllocToken.rst b/clang/docs/AllocToken.rst
index 7f3a128..bda8466 100644
--- a/clang/docs/AllocToken.rst
+++ b/clang/docs/AllocToken.rst
@@ -122,6 +122,35 @@ which encodes the token ID hint in the allocation function name.
 This ABI provides a more efficient alternative where
 ``-falloc-token-max`` is small.
 
+Instrumenting Non-Standard Allocation Functions
+-----------------------------------------------
+
+By default, AllocToken only instruments standard library allocation functions.
+This simplifies adoption, as a compatible allocator only needs to provide
+token-enabled variants for a well-defined set of standard functions.
+
+To extend instrumentation to custom allocation functions, enable broader
+coverage with ``-fsanitize-alloc-token-extended``. Such functions require being
+marked with the `malloc
+<https://clang.llvm.org/docs/AttributeReference.html#malloc>`_ or `alloc_size
+<https://clang.llvm.org/docs/AttributeReference.html#alloc-size>`_ attributes
+(or a combination).
+
+For example:
+
+.. code-block:: c
+
+    void *custom_malloc(size_t size) __attribute__((malloc));
+    void *my_malloc(size_t size) __attribute__((alloc_size(1)));
+
+    // Original:
+    ptr1 = custom_malloc(size);
+    ptr2 = my_malloc(size);
+
+    // Instrumented:
+    ptr1 = __alloc_token_custom_malloc(size, token_id);
+    ptr2 = __alloc_token_my_malloc(size, token_id);
+
 Disabling Instrumentation
 -------------------------