Commit b9976fa4 authored by Josh Poimboeuf's avatar Josh Poimboeuf
Browse files

livepatch: Introduce source code helpers for livepatch modules 



Add some helper macros which can be used by livepatch source .patch
files to register callbacks, convert static calls to regular calls where
needed, and patch syscalls.

Acked-by: default avatarPetr Mladek <pmladek@suse.com>
Tested-by: default avatarJoe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
parent 78be9fac

include/linux/livepatch_helpers.h

0 → 100644
+77 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

#ifndef _LINUX_LIVEPATCH_HELPERS_H

#define _LINUX_LIVEPATCH_HELPERS_H



/*

 * Interfaces for use by livepatch patches

 */



#include <linux/syscalls.h>

#include <linux/livepatch.h>



#ifdef MODULE

#define KLP_OBJNAME __KBUILD_MODNAME

#else

#define KLP_OBJNAME vmlinux

#endif



/* Livepatch callback registration */



#define KLP_CALLBACK_PTRS ".discard.klp_callback_ptrs"



#define KLP_PRE_PATCH_CALLBACK(func)						\

	klp_pre_patch_t __used __section(KLP_CALLBACK_PTRS)			\

		__PASTE(__KLP_PRE_PATCH_PREFIX, KLP_OBJNAME) = func



#define KLP_POST_PATCH_CALLBACK(func)						\

	klp_post_patch_t __used __section(KLP_CALLBACK_PTRS)			\

		__PASTE(__KLP_POST_PATCH_PREFIX, KLP_OBJNAME) = func



#define KLP_PRE_UNPATCH_CALLBACK(func)						\

	klp_pre_unpatch_t __used __section(KLP_CALLBACK_PTRS)			\

		__PASTE(__KLP_PRE_UNPATCH_PREFIX, KLP_OBJNAME) = func



#define KLP_POST_UNPATCH_CALLBACK(func)						\

	klp_post_unpatch_t __used __section(KLP_CALLBACK_PTRS)			\

		__PASTE(__KLP_POST_UNPATCH_PREFIX, KLP_OBJNAME) = func



/*

 * Replace static_call() usage with this macro when create-diff-object

 * recommends it due to the original static call key living in a module.

 *

 * This converts the static call to a regular indirect call.

 */

#define KLP_STATIC_CALL(name) \

	((typeof(STATIC_CALL_TRAMP(name))*)(STATIC_CALL_KEY(name).func))



/* Syscall patching */



#define KLP_SYSCALL_DEFINE1(name, ...) KLP_SYSCALL_DEFINEx(1, _##name, __VA_ARGS__)

#define KLP_SYSCALL_DEFINE2(name, ...) KLP_SYSCALL_DEFINEx(2, _##name, __VA_ARGS__)

#define KLP_SYSCALL_DEFINE3(name, ...) KLP_SYSCALL_DEFINEx(3, _##name, __VA_ARGS__)

#define KLP_SYSCALL_DEFINE4(name, ...) KLP_SYSCALL_DEFINEx(4, _##name, __VA_ARGS__)

#define KLP_SYSCALL_DEFINE5(name, ...) KLP_SYSCALL_DEFINEx(5, _##name, __VA_ARGS__)

#define KLP_SYSCALL_DEFINE6(name, ...) KLP_SYSCALL_DEFINEx(6, _##name, __VA_ARGS__)



#define KLP_SYSCALL_DEFINEx(x, sname, ...)				\

	__KLP_SYSCALL_DEFINEx(x, sname, __VA_ARGS__)



#ifdef CONFIG_X86_64

// TODO move this to arch/x86/include/asm/syscall_wrapper.h and share code

#define __KLP_SYSCALL_DEFINEx(x, name, ...)			\

	static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__));	\

	static inline long __klp_do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\

	__X64_SYS_STUBx(x, name, __VA_ARGS__)				\

	__IA32_SYS_STUBx(x, name, __VA_ARGS__)				\

	static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__))	\

	{								\

		long ret = __klp_do_sys##name(__MAP(x,__SC_CAST,__VA_ARGS__));\

		__MAP(x,__SC_TEST,__VA_ARGS__);				\

		__PROTECT(x, ret,__MAP(x,__SC_ARGS,__VA_ARGS__));	\

		return ret;						\

	}								\

	static inline long __klp_do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))



#endif



#endif /* _LINUX_LIVEPATCH_HELPERS_H */