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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (C) 2024 Google LLC
*
* Example macros for maintaining kABI stability.
*
* This file is based on android_kabi.h, which has the following notice:
*
* Heavily influenced by rh_kabi.h which came from the RHEL/CENTOS kernel
* and was:
* Copyright (c) 2014 Don Zickus
* Copyright (c) 2015-2018 Jiri Benc
* Copyright (c) 2015 Sabrina Dubroca, Hannes Frederic Sowa
* Copyright (c) 2016-2018 Prarit Bhargava
* Copyright (c) 2017 Paolo Abeni, Larry Woodman
*/
#ifndef __KABI_H__
#define __KABI_H__
/* Kernel macros for userspace testing. */
#ifndef __aligned
#define __aligned(x) __attribute__((__aligned__(x)))
#endif
#ifndef __used
#define __used __attribute__((__used__))
#endif
#ifndef __section
#define __section(section) __attribute__((__section__(section)))
#endif
#ifndef __PASTE
#define ___PASTE(a, b) a##b
#define __PASTE(a, b) ___PASTE(a, b)
#endif
#ifndef __stringify
#define __stringify_1(x...) #x
#define __stringify(x...) __stringify_1(x)
#endif
#define __KABI_RULE(hint, target, value) \
static const char __PASTE(__gendwarfksyms_rule_, \
__COUNTER__)[] __used __aligned(1) \
__section(".discard.gendwarfksyms.kabi_rules") = \
"1\0" #hint "\0" #target "\0" #value
#define __KABI_NORMAL_SIZE_ALIGN(_orig, _new) \
union { \
_Static_assert( \
sizeof(struct { _new; }) <= sizeof(struct { _orig; }), \
__FILE__ ":" __stringify(__LINE__) ": " __stringify( \
_new) " is larger than " __stringify(_orig)); \
_Static_assert( \
__alignof__(struct { _new; }) <= \
__alignof__(struct { _orig; }), \
__FILE__ ":" __stringify(__LINE__) ": " __stringify( \
_orig) " is not aligned the same as " __stringify(_new)); \
}
#define __KABI_REPLACE(_orig, _new) \
union { \
_new; \
struct { \
_orig; \
}; \
__KABI_NORMAL_SIZE_ALIGN(_orig, _new); \
}
/*
* KABI_DECLONLY(fqn)
* Treat the struct/union/enum fqn as a declaration, i.e. even if
* a definition is available, don't expand the contents.
*/
#define KABI_DECLONLY(fqn) __KABI_RULE(declonly, fqn, )
/*
* KABI_ENUMERATOR_IGNORE(fqn, field)
* When expanding enum fqn, skip the provided field. This makes it
* possible to hide added enum fields from versioning.
*/
#define KABI_ENUMERATOR_IGNORE(fqn, field) \
__KABI_RULE(enumerator_ignore, fqn field, )
/*
* KABI_ENUMERATOR_VALUE(fqn, field, value)
* When expanding enum fqn, use the provided value for the
* specified field. This makes it possible to override enumerator
* values when calculating versions.
*/
#define KABI_ENUMERATOR_VALUE(fqn, field, value) \
__KABI_RULE(enumerator_value, fqn field, value)
/*
* KABI_RESERVE
* Reserve some "padding" in a structure for use by LTS backports.
* This is normally placed at the end of a structure.
* number: the "number" of the padding variable in the structure. Start with
* 1 and go up.
*/
#define KABI_RESERVE(n) unsigned long __kabi_reserved##n
/*
* KABI_RESERVE_ARRAY
* Same as _BACKPORT_RESERVE but allocates an array with the specified
* size in bytes.
*/
#define KABI_RESERVE_ARRAY(n, s) \
unsigned char __aligned(8) __kabi_reserved##n[s]
/*
* KABI_IGNORE
* Add a new field that's ignored in versioning.
*/
#define KABI_IGNORE(n, _new) \
union { \
_new; \
unsigned char __kabi_ignored##n; \
}
/*
* KABI_REPLACE
* Replace a field with a compatible new field.
*/
#define KABI_REPLACE(_oldtype, _oldname, _new) \
__KABI_REPLACE(_oldtype __kabi_renamed##_oldname, struct { _new; })
/*
* KABI_USE(number, _new)
* Use a previous padding entry that was defined with KABI_RESERVE
* number: the previous "number" of the padding variable
* _new: the variable to use now instead of the padding variable
*/
#define KABI_USE(number, _new) __KABI_REPLACE(KABI_RESERVE(number), _new)
/*
* KABI_USE2(number, _new1, _new2)
* Use a previous padding entry that was defined with KABI_RESERVE for
* two new variables that fit into 64 bits. This is good for when you do not
* want to "burn" a 64bit padding variable for a smaller variable size if not
* needed.
*/
#define KABI_USE2(number, _new1, _new2) \
__KABI_REPLACE( \
KABI_RESERVE(number), struct { \
_new1; \
_new2; \
})
/*
* KABI_USE_ARRAY(number, bytes, _new)
* Use a previous padding entry that was defined with KABI_RESERVE_ARRAY
* number: the previous "number" of the padding variable
* bytes: the size in bytes reserved for the array
* _new: the variable to use now instead of the padding variable
*/
#define KABI_USE_ARRAY(number, bytes, _new) \
__KABI_REPLACE(KABI_RESERVE_ARRAY(number, bytes), _new)
#endif /* __KABI_H__ */
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