Commit 19514910 authored by Petr Mladek's avatar Petr Mladek Committed by Jiri Kosina
Browse files

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: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: default avatarPetr Mladek <pmladek@suse.com>
Acked-by: default avatarMiroslav Benes <mbenes@suse.cz>
Acked-by: default avatarJoe Lawrence <joe.lawrence@redhat.com>
Acked-by: default avatarAlice Ferrazzi <alice.ferrazzi@gmail.com>
Acked-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
parent 1686cc1a

include/linux/livepatch.h

+2 −2
Original line number Diff line number Diff line
@@ -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;

kernel/livepatch/core.c

+3 −3
Original line number Diff line number Diff line
@@ -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",

kernel/livepatch/patch.c

+10 −8
Original line number Diff line number Diff line
@@ -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);

kernel/livepatch/patch.h

+2 −2
Original line number Diff line number Diff line
@@ -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);

kernel/livepatch/transition.c

+2 −2
Original line number Diff line number Diff line
@@ -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 */

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