1 files changed, 67 insertions, 0 deletions
diff --git a/include/lmkd_hooks.h b/include/lmkd_hooks.h
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+++ b/include/lmkd_hooks.h
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+/*
+ *  Copyright 2022 Google, Inc
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+/*
+ * This file defines no-op hook functions for LMKD. To override these
+ * definitions, enable the use_lmkd_hooks product variable and create a library
+ * "liblmkdhooks" that supplies definitions for the hook functions in your
+ * vendor folder.
+ */
+
+#ifndef _LMKD_HOOKS_H_
+#define _LMKD_HOOKS_H_
+
+#include <sys/types.h>
+
+__BEGIN_DECLS
+
+#ifdef LMKD_USE_HOOKS
+
+/*
+ * Initialize all necessary Android props and perform any necessary validation
+ * on the values. Called before lmkd_init_hook() and will be called again
+ * whenever LMKD receives the LMK_UPDATE_PROPS command. Returns true on success,
+ * false otherwise.
+ */
+bool lmkd_update_props_hook();
+/*
+ * Perform any necessary initialization for the hooks. Called only once at the
+ * end of LMKD's init(). Returns true on success, false otherwise.
+ */
+bool lmkd_init_hook();
+/*
+ * Allows for interception of a kill by LMKD. This hook may attempt to free
+ * memory elsewhere to avoid the specified process being killed. Returns 0 to
+ * proceed with the kill, or the number of memory pages freed elsewhere to skip
+ * the kill.
+ */
+int lmkd_free_memory_before_kill_hook(struct proc* procp, int proc_size_pages,
+                                      int proc_oom_score, int kill_reason);
+
+#else /* LMKD_USE_HOOKS */
+
+static inline bool lmkd_update_props_hook() { return true; }
+static inline bool lmkd_init_hook() { return true; }
+static inline int lmkd_free_memory_before_kill_hook(struct proc*, int, int,
+                                                    int) {
+  return 0;
+}
+
+#endif /* LMKD_USE_HOOKS */
+
+__END_DECLS
+
+#endif