Edit File: rh_kabi.h
/* * rh_kabi.h - Red Hat kabi abstraction header * * Copyright (c) 2014 Don Zickus * * This file is released under the GPLv2. * See the file COPYING for more details. * * "Anyone can make KABI pass, not everyone can fix it." * - Don Zickus * * The use of these macros does not guarantee that the usage and modification * of code is correct. As with all Red Hat only changes, an engineer must * explain why the use of the macro is valid in the patch containing the * changes. * */ #ifndef _LINUX_RH_KABI_H #define _LINUX_RH_KABI_H #include <linux/compiler.h> #include <linux/stringify.h> /* * The RH_KABI_REPLACE* macros attempt to add the ability to use the '_new' * element while preserving size alignment and kabi agreement with the '_orig' * element. * * The #ifdef __GENKSYMS__ preserves the kabi agreement, while the anonymous * union structure preserves the size alignment (assuming the '_new' element is * not bigger than the '_orig' element). * * RH_KABI_REPLACE - simple replacement of _orig with a union of _orig and _new * RH_KABI_DEPRECATE - mark the element as deprecated and make it unusable * by modules while preserving kABI checksums * RH_KABI_DEPRECATE_FN - mark the function pointer as deprecated and make it * unusable by modules while preserving kABI checksums * * RH_KABI_EXTEND - simple macro for adding a new element to a struct while * preserving the kabi agreement (by wrapping with GENKSYMS). * RH_KABI_FILL_HOLE - simple macro for filling a hole in a struct while * preserving the kabi agreement (by wrapping with GENKSYMS). * RH_KABI_RENAME - simple macro for renaming an element without changing its type * while preserving thi kabi agreement (by wrapping with GENKSYMS). * This macro can be used in bitfields, for example. * NOTE: does not include the final ';' * RH_KABI_REPLACE_UNSAFE - unsafe version of RH_KABI_REPLACE. Only use for typedefs. * * NOTE NOTE NOTE * Don't use ';' after these macros as it messes up the kabi checker by * changing what the resulting token string looks like. * Instead let this macro add the ';' so it can be properly hidden from * the kabi checker (mainly for RH_KABI_EXTEND, but applied to all macros for * uniformity). * NOTE NOTE NOTE * * RH_KABI_CONST - adds a new const modifier to a function parameter * preserving the old checksum * * This macro does the opposite: it changes the symbol checksum without * actually changing anything about the exported symbol. It is useful for * symbols that are not whitelisted, we're changing them in an incompatible * way and want to prevent 3rd party modules to silently corrupt memory. * Instead, by changing the symbol checksum, such modules won't be loaded by * the kernel. This macro should only be used as a last resort when all other * KABI workarounds have failed. * * RH_KABI_FORCE_CHANGE - Force change of the symbol checksum. The argument * of the macro is a version for cases we need to do * this more than once. */ #ifdef __GENKSYMS__ # define _RH_KABI_REPLACE(_orig, _new) _orig # define _RH_KABI_REPLACE_UNSAFE(_orig, _new) _orig # define _RH_KABI_DEPRECATE(_type, _orig) _type _orig # define _RH_KABI_DEPRECATE_FN(_type, _orig, _args...) _type (*_orig)(_args) # define RH_KABI_EXTEND(_new) # define RH_KABI_FILL_HOLE(_new) # define RH_KABI_RENAME(_orig, _new) _orig # define RH_KABI_CONST # define RH_KABI_FORCE_CHANGE(ver) __attribute__((rh_kabi_change ## ver)) #else #define RH_KABI_ALIGN_WARNING ". Disable CONFIG_RH_KABI_SIZE_ALIGN_CHECKS if debugging." #if IS_BUILTIN(CONFIG_RH_KABI_SIZE_ALIGN_CHECKS) #define __RH_KABI_CHECK_SIZE_ALIGN(_orig, _new) \ union { \ _Static_assert(sizeof(struct{_new;}) <= sizeof(struct{_orig;}), \ __FILE__ ":" __stringify(__LINE__) ": " __stringify(_new) " is larger than " __stringify(_orig) RH_KABI_ALIGN_WARNING); \ _Static_assert(__alignof__(struct{_new;}) <= __alignof__(struct{_orig;}), \ __FILE__ ":" __stringify(__LINE__) ": " __stringify(_orig) " is not aligned the same as " __stringify(_new) RH_KABI_ALIGN_WARNING); \ } #else #define __RH_KABI_CHECK_SIZE_ALIGN(_orig, _new) #endif # define _RH_KABI_REPLACE(_orig, _new) \ union { \ _new; \ struct { \ _orig; \ } __UNIQUE_ID(rh_kabi_hide); \ __RH_KABI_CHECK_SIZE_ALIGN(_orig, _new); \ } #define _RH_KABI_REPLACE_UNSAFE(_orig, _new) _new # define _RH_KABI_DEPRECATE(_type, _orig) _type rh_reserved_##_orig # define _RH_KABI_DEPRECATE_FN(_type, _orig, _args...) \ _type (* rh_reserved_##_orig)(_args) # define RH_KABI_EXTEND(_new) _new; /* Warning, only use if a hole exists for _all_ arches. Use pahole to verify */ # define RH_KABI_FILL_HOLE(_new) _new; # define RH_KABI_RENAME(_orig, _new) _new # define RH_KABI_CONST const # define RH_KABI_FORCE_CHANGE(ver) #endif /* __GENKSYMS__ */ /* colon added wrappers for the RH_KABI_REPLACE macros */ #define RH_KABI_REPLACE(_orig, _new) _RH_KABI_REPLACE(_orig, _new); #define RH_KABI_REPLACE_UNSAFE(_orig, _new) _RH_KABI_REPLACE_UNSAFE(_orig, _new); #define RH_KABI_DEPRECATE(_type, _orig) _RH_KABI_DEPRECATE(_type, _orig); #define RH_KABI_DEPRECATE_FN(_type, _orig, _args...) \ _RH_KABI_DEPRECATE_FN(_type, _orig, _args); /* * We tried to standardize on Red Hat reserved names. These wrappers leverage * those common names making it easier to read and find in the code. */ #define _RH_KABI_RESERVE(n) unsigned long rh_reserved##n #define _RH_KABI_RESERVE_P(n) void (*rh_reserved##n)(void) #define RH_KABI_RESERVE(n) _RH_KABI_RESERVE(n); #define RH_KABI_RESERVE_P(n) _RH_KABI_RESERVE_P(n); /* * Simple wrappers to replace standard Red Hat reserved elements. */ #define RH_KABI_USE(n, _new) RH_KABI_REPLACE(_RH_KABI_RESERVE(n), _new) #define RH_KABI_USE_P(n, _new) RH_KABI_REPLACE(_RH_KABI_RESERVE_P(n), _new) /* * Macros for breaking up a reserved element into two smaller chunks using an * anonymous struct inside an anonymous union. */ #define RH_KABI_USE2(n, _new1, _new2) RH_KABI_REPLACE(_RH_KABI_RESERVE(n), struct{ _new1; _new2; }) #define RH_KABI_USE2_P(n, _new1, _new2) RH_KABI_REPLACE(_RH_KABI_RESERVE_P(n), struct{ _new1; _new2;}) /* * Macro for breaking up a random element into two smaller chunks using an anonymous * struct inside an anonymous union. */ #define RH_KABI_REPLACE2(orig, _new1, _new2) RH_KABI_REPLACE(orig, struct{ _new1; _new2;}) #endif /* _LINUX_RH_KABI_H */