Merge branch 'topic/livepatch' of git://git.kernel.org/pub/scm/linux/kernel/git/power...

[cascardo/linux.git] / kernel / livepatch / core.c

diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 28c37fa..a19f195 100644 (file)
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -334,6 +334,19 @@ unlock:
        rcu_read_unlock();
 }
 
+/*
+ * Convert a function address into the appropriate ftrace location.
+ *
+ * Usually this is just the address of the function, but on some architectures
+ * it's more complicated so allow them to provide a custom behaviour.
+ */
+#ifndef klp_get_ftrace_location
+static unsigned long klp_get_ftrace_location(unsigned long faddr)
+{
+       return faddr;
+}
+#endif
+
 static void klp_disable_func(struct klp_func *func)
 {
        struct klp_ops *ops;
@@ -348,8 +361,14 @@ static void klp_disable_func(struct klp_func *func)
                return;
 
        if (list_is_singular(&ops->func_stack)) {
+               unsigned long ftrace_loc;
+
+               ftrace_loc = klp_get_ftrace_location(func->old_addr);
+               if (WARN_ON(!ftrace_loc))
+                       return;
+
                WARN_ON(unregister_ftrace_function(&ops->fops));
-               WARN_ON(ftrace_set_filter_ip(&ops->fops, func->old_addr, 1, 0));
+               WARN_ON(ftrace_set_filter_ip(&ops->fops, ftrace_loc, 1, 0));
 
                list_del_rcu(&func->stack_node);
                list_del(&ops->node);
@@ -374,6 +393,15 @@ static int klp_enable_func(struct klp_func *func)
 
        ops = klp_find_ops(func->old_addr);
        if (!ops) {
+               unsigned long ftrace_loc;
+
+               ftrace_loc = klp_get_ftrace_location(func->old_addr);
+               if (!ftrace_loc) {
+                       pr_err("failed to find location for function '%s'\n",
+                               func->old_name);
+                       return -EINVAL;
+               }
+
                ops = kzalloc(sizeof(*ops), GFP_KERNEL);
                if (!ops)
                        return -ENOMEM;
@@ -388,7 +416,7 @@ static int klp_enable_func(struct klp_func *func)
                INIT_LIST_HEAD(&ops->func_stack);
                list_add_rcu(&func->stack_node, &ops->func_stack);
 
-               ret = ftrace_set_filter_ip(&ops->fops, func->old_addr, 0, 0);
+               ret = ftrace_set_filter_ip(&ops->fops, ftrace_loc, 0, 0);
                if (ret) {
                        pr_err("failed to set ftrace filter for function '%s' (%d)\n",
                               func->old_name, ret);
@@ -399,7 +427,7 @@ static int klp_enable_func(struct klp_func *func)
                if (ret) {
                        pr_err("failed to register ftrace handler for function '%s' (%d)\n",
                               func->old_name, ret);
-                       ftrace_set_filter_ip(&ops->fops, func->old_addr, 1, 0);
+                       ftrace_set_filter_ip(&ops->fops, ftrace_loc, 1, 0);
                        goto err;
                }