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-rw-r--r--lib/kunit/static_stub.c123
1 files changed, 123 insertions, 0 deletions
diff --git a/lib/kunit/static_stub.c b/lib/kunit/static_stub.c
new file mode 100644
index 0000000000..92b2cccd5e
--- /dev/null
+++ b/lib/kunit/static_stub.c
@@ -0,0 +1,123 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KUnit function redirection (static stubbing) API.
+ *
+ * Copyright (C) 2022, Google LLC.
+ * Author: David Gow <davidgow@google.com>
+ */
+
+#include <kunit/test.h>
+#include <kunit/static_stub.h>
+#include "hooks-impl.h"
+
+
+/* Context for a static stub. This is stored in the resource data. */
+struct kunit_static_stub_ctx {
+ void *real_fn_addr;
+ void *replacement_addr;
+};
+
+static void __kunit_static_stub_resource_free(struct kunit_resource *res)
+{
+ kfree(res->data);
+}
+
+/* Matching function for kunit_find_resource(). match_data is real_fn_addr. */
+static bool __kunit_static_stub_resource_match(struct kunit *test,
+ struct kunit_resource *res,
+ void *match_real_fn_addr)
+{
+ /* This pointer is only valid if res is a static stub resource. */
+ struct kunit_static_stub_ctx *ctx = res->data;
+
+ /* Make sure the resource is a static stub resource. */
+ if (res->free != &__kunit_static_stub_resource_free)
+ return false;
+
+ return ctx->real_fn_addr == match_real_fn_addr;
+}
+
+/* Hook to return the address of the replacement function. */
+void *__kunit_get_static_stub_address_impl(struct kunit *test, void *real_fn_addr)
+{
+ struct kunit_resource *res;
+ struct kunit_static_stub_ctx *ctx;
+ void *replacement_addr;
+
+ res = kunit_find_resource(test,
+ __kunit_static_stub_resource_match,
+ real_fn_addr);
+
+ if (!res)
+ return NULL;
+
+ ctx = res->data;
+ replacement_addr = ctx->replacement_addr;
+ kunit_put_resource(res);
+ return replacement_addr;
+}
+
+void kunit_deactivate_static_stub(struct kunit *test, void *real_fn_addr)
+{
+ struct kunit_resource *res;
+
+ KUNIT_ASSERT_PTR_NE_MSG(test, real_fn_addr, NULL,
+ "Tried to deactivate a NULL stub.");
+
+ /* Look up the existing stub for this function. */
+ res = kunit_find_resource(test,
+ __kunit_static_stub_resource_match,
+ real_fn_addr);
+
+ /* Error out if the stub doesn't exist. */
+ KUNIT_ASSERT_PTR_NE_MSG(test, res, NULL,
+ "Tried to deactivate a nonexistent stub.");
+
+ /* Free the stub. We 'put' twice, as we got a reference
+ * from kunit_find_resource()
+ */
+ kunit_remove_resource(test, res);
+ kunit_put_resource(res);
+}
+EXPORT_SYMBOL_GPL(kunit_deactivate_static_stub);
+
+/* Helper function for kunit_activate_static_stub(). The macro does
+ * typechecking, so use it instead.
+ */
+void __kunit_activate_static_stub(struct kunit *test,
+ void *real_fn_addr,
+ void *replacement_addr)
+{
+ struct kunit_static_stub_ctx *ctx;
+ struct kunit_resource *res;
+
+ KUNIT_ASSERT_PTR_NE_MSG(test, real_fn_addr, NULL,
+ "Tried to activate a stub for function NULL");
+
+ /* If the replacement address is NULL, deactivate the stub. */
+ if (!replacement_addr) {
+ kunit_deactivate_static_stub(test, replacement_addr);
+ return;
+ }
+
+ /* Look up any existing stubs for this function, and replace them. */
+ res = kunit_find_resource(test,
+ __kunit_static_stub_resource_match,
+ real_fn_addr);
+ if (res) {
+ ctx = res->data;
+ ctx->replacement_addr = replacement_addr;
+
+ /* We got an extra reference from find_resource(), so put it. */
+ kunit_put_resource(res);
+ } else {
+ ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ctx);
+ ctx->real_fn_addr = real_fn_addr;
+ ctx->replacement_addr = replacement_addr;
+ res = kunit_alloc_resource(test, NULL,
+ &__kunit_static_stub_resource_free,
+ GFP_KERNEL, ctx);
+ }
+}
+EXPORT_SYMBOL_GPL(__kunit_activate_static_stub);