livepatch: Change unsigned long old_addr -> void *old_func in struct klp_func

The address of the to be patched function and new function is stored
in struct klp_func as:

	void *new_func;
	unsigned long old_addr;

The different naming scheme and type are derived from the way
the addresses are set. @old_addr is assigned at runtime using
kallsyms-based search. @new_func is statically initialized,
for example:

  static struct klp_func funcs[] = {
	{
		.old_name = "cmdline_proc_show",
		.new_func = livepatch_cmdline_proc_show,
	}, { }
  };

This patch changes unsigned long old_addr -> void *old_func. It removes
some confusion when these address are later used in the code. It is
motivated by a followup patch that adds special NOP struct klp_func
where we want to assign func->new_func = func->old_addr respectively
func->new_func = func->old_func.

This patch does not modify the existing behavior.

Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Alice Ferrazzi <alice.ferrazzi@gmail.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

5 files changed, 19 insertions, 17 deletions

diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index aec44b1d9582..634e13876380 100644
--- a/include/linux/livepatch.h
+++ b/include/linux/livepatch.h
@@ -40,7 +40,7 @@
  * @new_func:   pointer to the patched function code
  * @old_sympos: a hint indicating which symbol position the old function
  *              can be found (optional)
- * @old_addr:   the address of the function being patched
+ * @old_func:   pointer to the function being patched
  * @kobj:       kobject for sysfs resources
  * @stack_node: list node for klp_ops func_stack list
  * @old_size:   size of the old function
@@ -77,7 +77,7 @@ struct klp_func {
         unsigned long old_sympos;
 
         /* internal */
-        unsigned long old_addr;
+        void *old_func;
         struct kobject kobj;
         struct list_head stack_node;
         unsigned long old_size, new_size;
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 5b77a7314e01..cb59c7fb94cb 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -648,7 +648,7 @@ static void klp_free_object_loaded(struct klp_object *obj)
         obj->mod = NULL;
 
         klp_for_each_func(obj, func)
-                func->old_addr = 0;
+                func->old_func = NULL;
 }
 
 /*
@@ -721,11 +721,11 @@ static int klp_init_object_loaded(struct klp_patch *patch,
         klp_for_each_func(obj, func) {
                 ret = klp_find_object_symbol(obj->name, func->old_name,
                                              func->old_sympos,
-                                             &func->old_addr);
+                                             (unsigned long *)&func->old_func);
                 if (ret)
                         return ret;
 
-                ret = kallsyms_lookup_size_offset(func->old_addr,
+                ret = kallsyms_lookup_size_offset((unsigned long)func->old_func,
                                                   &func->old_size, NULL);
                 if (!ret) {
                         pr_err("kallsyms size lookup failed for '%s'\n",
diff --git a/kernel/livepatch/patch.c b/kernel/livepatch/patch.c
index 7702cb4064fc..825022d70912 100644
--- a/kernel/livepatch/patch.c
+++ b/kernel/livepatch/patch.c
@@ -34,7 +34,7 @@
 
 static LIST_HEAD(klp_ops);
 
-struct klp_ops *klp_find_ops(unsigned long old_addr)
+struct klp_ops *klp_find_ops(void *old_func)
 {
         struct klp_ops *ops;
         struct klp_func *func;
@@ -42,7 +42,7 @@ struct klp_ops *klp_find_ops(unsigned long old_addr)
         list_for_each_entry(ops, &klp_ops, node) {
                 func = list_first_entry(&ops->func_stack, struct klp_func,
                                         stack_node);
-                if (func->old_addr == old_addr)
+                if (func->old_func == old_func)
                         return ops;
         }
 
@@ -142,17 +142,18 @@ static void klp_unpatch_func(struct klp_func *func)
 
         if (WARN_ON(!func->patched))
                 return;
-        if (WARN_ON(!func->old_addr))
+        if (WARN_ON(!func->old_func))
                 return;
 
-        ops = klp_find_ops(func->old_addr);
+        ops = klp_find_ops(func->old_func);
         if (WARN_ON(!ops))
                 return;
 
         if (list_is_singular(&ops->func_stack)) {
                 unsigned long ftrace_loc;
 
-                ftrace_loc = klp_get_ftrace_location(func->old_addr);
+                ftrace_loc =
+                        klp_get_ftrace_location((unsigned long)func->old_func);
                 if (WARN_ON(!ftrace_loc))
                         return;
 
@@ -174,17 +175,18 @@ static int klp_patch_func(struct klp_func *func)
         struct klp_ops *ops;
         int ret;
 
-        if (WARN_ON(!func->old_addr))
+        if (WARN_ON(!func->old_func))
                 return -EINVAL;
 
         if (WARN_ON(func->patched))
                 return -EINVAL;
 
-        ops = klp_find_ops(func->old_addr);
+        ops = klp_find_ops(func->old_func);
         if (!ops) {
                 unsigned long ftrace_loc;
 
-                ftrace_loc = klp_get_ftrace_location(func->old_addr);
+                ftrace_loc =
+                        klp_get_ftrace_location((unsigned long)func->old_func);
                 if (!ftrace_loc) {
                         pr_err("failed to find location for function '%s'\n",
                                 func->old_name);
diff --git a/kernel/livepatch/patch.h b/kernel/livepatch/patch.h
index e72d8250d04b..a9b16e513656 100644
--- a/kernel/livepatch/patch.h
+++ b/kernel/livepatch/patch.h
@@ -10,7 +10,7 @@
  * struct klp_ops - structure for tracking registered ftrace ops structs
  *
  * A single ftrace_ops is shared between all enabled replacement functions
- * (klp_func structs) which have the same old_addr.  This allows the switch
+ * (klp_func structs) which have the same old_func.  This allows the switch
  * between function versions to happen instantaneously by updating the klp_ops
  * struct's func_stack list.  The winner is the klp_func at the top of the
  * func_stack (front of the list).
@@ -25,7 +25,7 @@ struct klp_ops {
         struct ftrace_ops fops;
 };
 
-struct klp_ops *klp_find_ops(unsigned long old_addr);
+struct klp_ops *klp_find_ops(void *old_func);
 
 int klp_patch_object(struct klp_object *obj);
 void klp_unpatch_object(struct klp_object *obj);
diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index 304d5eb8a98c..f27a378ad5e1 100644
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -224,11 +224,11 @@ static int klp_check_stack_func(struct klp_func *func,
                          * Check for the to-be-patched function
                          * (the previous func).
                          */
-                        ops = klp_find_ops(func->old_addr);
+                        ops = klp_find_ops(func->old_func);
 
                         if (list_is_singular(&ops->func_stack)) {
                                 /* original function */
-                                func_addr = func->old_addr;
+                                func_addr = (unsigned long)func->old_func;
                                 func_size = func->old_size;
                         } else {
                                 /* previously patched function */