From: Zheng Zengkai zhengzengkai@huawei.com
hulk inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I8LQBH
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We intruduce kabi helper macros which derived from RHEL "include/linux/rh_kabi.h", tried to standardize the kabi work on openEuler.
Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com Signed-off-by: Xie XiuQi xiexiuqi@huawei.com Reviewed-by: Cheng Jian cj.chengjian@huawei.com Signed-off-by: Jialin Zhang zhangjialin11@huawei.com --- include/linux/kabi.h | 499 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 499 insertions(+) create mode 100644 include/linux/kabi.h
diff --git a/include/linux/kabi.h b/include/linux/kabi.h new file mode 100644 index 000000000000..0f25a84809c3 --- /dev/null +++ b/include/linux/kabi.h @@ -0,0 +1,499 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * kabi.h - openEuler kABI abstraction header + * + * 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 + * Copyright (c) 2021 Xie XiuQi xiexiuqi@huawei.com + * + * This file is released under the GPLv2. + * See the file COPYING for more details. + * + * These kabi macros hide the changes from the kabi checker and from the + * process that computes the exported symbols' checksums. + * They have 2 variants: one (defined under __GENKSYMS__) used when + * generating the checksums, and the other used when building the kernel's + * binaries. + * + * The use of these macros does not guarantee that the usage and modification + * of code is correct. As with all openEuler only changes, an engineer must + * explain why the use of the macro is valid in the patch containing the + * changes. + * + * The macro helpers are derived from RHEL "include/linux/rh_kabi.h" + * Mostly debrand from RHEL. + */ + +#ifndef _LINUX_KABI_H +#define _LINUX_KABI_H + +#include <linux/compiler.h> +#include <linux/stringify.h> + +/* + * NOTE + * Unless indicated otherwise, don't use ';' after these macros as it + * messes up the kABI checker by changing what the resulting token string + * looks like. Instead let the macros add the ';' so it can be properly + * hidden from the kABI checker (mainly for KABI_EXTEND, but applied to + * most macros for uniformity). + * + * KABI_CONST + * Adds a new const modifier to a function parameter preserving the old + * checksum. + * + * KABI_ADD_MODIFIER + * Adds a new modifier to a function parameter or a typedef, preserving + * the old checksum. Useful e.g. for adding rcu annotations or changing + * int to unsigned. Beware that this may change the semantics; if you're + * sure this is safe, always explain why binary compatibility with 3rd + * party modules is retained. + * + * KABI_DEPRECATE + * Marks the element as deprecated and make it unusable by modules while + * keeping a hole in its place to preserve binary compatibility. + * + * # define KABI_BROKEN_INSERT_ENUM(_new) _new, + * # define KABI_BROKEN_REMOVE_ENUM(_orig) + * KABI_DEPRECATE_FN + * Marks the function pointer as deprecated and make it unusable by modules + * while keeping a hole in its place to preserve binary compatibility. + * + * KABI_EXTEND + * Adds a new field to a struct. This must always be added to the end of + * the struct. Before using this macro, make sure this is actually safe + * to do - there is a number of conditions under which it is *not* safe. + * In particular (but not limited to), this macro cannot be used: + * - if the struct in question is embedded in another struct, or + * - if the struct is allocated by drivers either statically or + * dynamically, or + * - if the struct is allocated together with driver data (an example of + * such behavior is struct net_device or struct request). + * + * KABI_EXTEND_WITH_SIZE + * Adds a new element (usually a struct) to a struct and reserves extra + * space for the new element. The provided 'size' is the total space to + * be added in longs (i.e. it's 8 * 'size' bytes), including the size of + * the added element. It is automatically checked that the new element + * does not overflow the reserved space, now nor in the future. However, + * no attempt is done to check the content of the added element (struct) + * for kABI conformance - kABI checking inside the added element is + * effectively switched off. + * For any struct being added by KABI_EXTEND_WITH_SIZE, it is + * recommended its content to be documented as not covered by kABI + * guarantee. + * + * KABI_FILL_HOLE + * Fills a hole in a struct. + * + * Warning: only use if a hole exists for _all_ arches. Use pahole to verify. + * + * KABI_RENAME + * Renames an element without changing its type. This macro can be used in + * bitfields, for example. + * + * NOTE: does not include the final ';' + * + * KABI_REPLACE + * Replaces the _orig field by the _new field. The size of the occupied + * space is preserved, it's fine if the _new field is smaller than the + * _orig field. If a _new field is larger or has a different alignment, + * compilation will abort. + * + * + * KABI_HIDE_INCLUDE + * Hides the given include file from kABI checksum computations. This is + * used when a newly added #include makes a previously opaque struct + * visible. + * + * Example usage: + * #include KABI_HIDE_INCLUDE(<linux/poll.h>) + * + * KABI_FAKE_INCLUDE + * Pretends inclusion of the given file for kABI checksum computations. + * This is used when upstream removed a particular #include but that made + * some structures opaque that were previously visible and is causing kABI + * checker failures. + * + * Example usage: + * #include KABI_FAKE_INCLUDE(<linux/rhashtable.h>) + * + * KABI_RESERVE + * Adds a reserved field to a struct. This is done prior to kABI freeze + * for structs that cannot be expanded later using KABI_EXTEND (for + * example because they are embedded in another struct or because they are + * allocated by drivers or because they use unusual memory layout). The + * size of the reserved field is 'unsigned long' and is assumed to be + * 8 bytes. + * + * The argument is a number unique for the given struct; usually, multiple + * KABI_RESERVE macros are added to a struct with numbers starting from + * one. + * + * Example usage: + * struct foo { + * int a; + * KABI_RESERVE(1) + * KABI_RESERVE(2) + * }; + * + * KABI_USE + * Simple wrappers to replace standard openEuler reserved elements. + * + * KABI_AUX_EMBED + * KABI_AUX_PTR + * Adds an extension of a struct in the form of "auxiliary structure". + * This is done prior to kABI freeze for structs that cannot be expanded + * later using KABI_EXTEND. See also KABI_RESERVED, these two + * approaches can (and often are) combined. + * + * To use this for 'struct foo' (the "base structure"), define a new + * structure called 'struct foo_rh'; this new struct is called "auxiliary + * structure". Then add KABI_AUX_EMBED or KABI_AUX_PTR to the end + * of the base structure. The argument is the name of the base structure, + * without the 'struct' keyword. + * + * KABI_AUX_PTR stores a pointer to the aux structure in the base + * struct. The lifecycle of the aux struct needs to be properly taken + * care of. + * + * KABI_AUX_EMBED embeds the aux struct into the base struct. This + * cannot be used when the base struct is itself embedded into another + * struct, allocated in an array, etc. + * + * Both approaches (ptr and embed) work correctly even when the aux struct + * is allocated by modules. To ensure this, the code responsible for + * allocation/assignment of the aux struct has to properly set the size of + * the aux struct; see the KABI_AUX_SET_SIZE and KABI_AUX_INIT_SIZE + * macros. + * + * New fields can be later added to the auxiliary structure, always to its + * end. Note the auxiliary structure cannot be shrunk in size later (i.e., + * fields cannot be removed, only deprecated). Any code accessing fields + * from the aux struct must guard the access using the KABI_AUX macro. + * The access itself is then done via a '_rh' field in the base struct. + * + * The auxiliary structure is not guaranteed for access by modules unless + * explicitly commented as such in the declaration of the aux struct + * itself or some of its elements. + * + * Example: + * + * struct foo_rh { + * int newly_added; + * }; + * + * struct foo { + * bool big_hammer; + * KABI_AUX_PTR(foo) + * }; + * + * void use(struct foo *f) + * { + * if (KABI_AUX(f, foo, newly_added)) + * f->_rh->newly_added = 123; + * else + * // the field 'newly_added' is not present in the passed + * // struct, fall back to old behavior + * f->big_hammer = true; + * } + * + * static struct foo_rh my_foo_rh { + * .newly_added = 0; + * } + * + * static struct foo my_foo = { + * .big_hammer = false, + * ._rh = &my_foo_rh, + * KABI_AUX_INIT_SIZE(foo) + * }; + * + * KABI_USE_AUX_PTR + * Creates an auxiliary structure post kABI freeze. This works by using + * two reserved fields (thus there has to be two reserved fields still + * available) and converting them to KABI_AUX_PTR. + * + * Example: + * + * struct foo_rh { + * }; + * + * struct foo { + * int a; + * KABI_RESERVE(1) + * KABI_USE_AUX_PTR(2, 3, foo) + * }; + * + * KABI_AUX_SET_SIZE + * KABI_AUX_INIT_SIZE + * Calculates and stores the size of the auxiliary structure. + * + * KABI_AUX_SET_SIZE is for dynamically allocated base structs, + * KABI_AUX_INIT_SIZE is for statically allocated case structs. + * + * These macros must be called from the allocation (KABI_AUX_SET_SIZE) + * or declaration (KABI_AUX_INIT_SIZE) site, regardless of whether + * that happens in the kernel or in a module. Without calling one of + * these macros, the aux struct will appear to have no fields to the + * kernel. + * + * Note: since KABI_AUX_SET_SIZE is intended to be invoked outside of + * a struct definition, it does not add the semicolon and must be + * terminated by semicolon by the caller. + * + * KABI_AUX + * Verifies that the given field exists in the given auxiliary structure. + * This MUST be called prior to accessing that field; failing to do that + * may lead to invalid memory access. + * + * The first argument is a pointer to the base struct, the second argument + * is the name of the base struct (without the 'struct' keyword), the + * third argument is the field name. + * + * This macro works for structs extended by either of KABI_AUX_EMBED, + * KABI_AUX_PTR and KABI_USE_AUX_PTR. + * + * 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. + * + * 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. + * + * KABI_EXCLUDE + * !!! WARNING: DANGEROUS, DO NOT USE unless you are aware of all the !!! + * !!! implications. This should be used ONLY EXCEPTIONALLY and only !!! + * !!! under specific circumstances. Very likely, this macro does not !!! + * !!! do what you expect it to do. Note that any usage of this macro !!! + * !!! MUST be paired with a KABI_FORCE_CHANGE annotation of !!! + * !!! a suitable symbol (or an equivalent safeguard) and the commit !!! + * !!! log MUST explain why the chosen solution is appropriate. !!! + * + * Exclude the element from checksum generation. Any such element is + * considered not to be part of the kABI whitelist and may be changed at + * will. Note however that it's the responsibility of the developer + * changing the element to ensure 3rd party drivers using this element + * won't panic, for example by not allowing them to be loaded. That can + * be achieved by changing another, non-whitelisted symbol they use, + * either by nature of the change or by using KABI_FORCE_CHANGE. + * + * Also note that any change to the element must preserve its size. Change + * of the size is not allowed and would constitute a silent kABI breakage. + * Beware that the KABI_EXCLUDE macro does not do any size checks. + * + * KABI_BROKEN_INSERT + * KABI_BROKEN_REMOVE + * Insert a field to the middle of a struct / delete a field from a struct. + * Note that this breaks kABI! It can be done only when it's certain that + * no 3rd party driver can validly reach into the struct. A typical + * example is a struct that is: both (a) referenced only through a long + * chain of pointers from another struct that is part of a whitelisted + * symbol and (b) kernel internal only, it should have never been visible + * to genksyms in the first place. + * + * Another example are structs that are explicitly exempt from kABI + * guarantee but we did not have enough foresight to use KABI_EXCLUDE. + * In this case, the warning for KABI_EXCLUDE applies. + * + * A detailed explanation of correctness of every KABI_BROKEN_* macro + * use is especially important. + * + * KABI_BROKEN_INSERT_BLOCK + * KABI_BROKEN_REMOVE_BLOCK + * A version of KABI_BROKEN_INSERT / REMOVE that allows multiple fields + * to be inserted or removed together. All fields need to be terminated + * by ';' inside(!) the macro parameter. The macro itself must not be + * terminated by ';'. + * + * KABI_BROKEN_REPLACE + * Replace a field by a different one without doing any checking. This + * allows replacing a field by another with a different size. Similarly + * to other KABI_BROKEN macros, use of this indicates a kABI breakage. + * + * KABI_BROKEN_INSERT_ENUM + * KABI_BROKEN_REMOVE_ENUM + * Insert a field to the middle of an enumaration type / delete a field from + * an enumaration type. Note that this can break kABI especially if the + * number of enum fields is used in an array within a structure. It can be + * done only when it is certain that no 3rd party driver will use the + * enumeration type or a structure that embeds an array with size determined + * by an enumeration type. + * + * KABI_EXTEND_ENUM + * Adds a new field to an enumeration type. This must always be added to + * the end of the enum. Before using this macro, make sure this is actually + * safe to do. + */ +#ifdef __GENKSYMS__ + +# define KABI_CONST +# define KABI_ADD_MODIFIER(_new) +# define KABI_EXTEND(_new) +# define KABI_FILL_HOLE(_new) +# define KABI_FORCE_CHANGE(ver) __attribute__((kabi_change ## ver)) +# define KABI_RENAME(_orig, _new) _orig +# define KABI_HIDE_INCLUDE(_file) <linux/kabi.h> +# define KABI_FAKE_INCLUDE(_file) _file +# define KABI_BROKEN_INSERT(_new) +# define KABI_BROKEN_REMOVE(_orig) _orig; +# define KABI_BROKEN_INSERT_BLOCK(_new) +# define KABI_BROKEN_REMOVE_BLOCK(_orig) _orig +# define KABI_BROKEN_REPLACE(_orig, _new) _orig; +# define KABI_BROKEN_INSERT_ENUM(_new) +# define KABI_BROKEN_REMOVE_ENUM(_orig) _orig, +# define KABI_EXTEND_ENUM(_new) + +# define _KABI_DEPRECATE(_type, _orig) _type _orig +# define _KABI_DEPRECATE_FN(_type, _orig, _args...) _type (*_orig)(_args) +# define _KABI_REPLACE(_orig, _new) _orig +# define _KABI_EXCLUDE(_elem) + +#else + +# define KABI_ALIGN_WARNING ". Disable CONFIG_KABI_SIZE_ALIGN_CHECKS if debugging." + +# define KABI_CONST const +# define KABI_ADD_MODIFIER(_new) _new +# define KABI_EXTEND(_new) _new; +# define KABI_FILL_HOLE(_new) _new; +# define KABI_FORCE_CHANGE(ver) +# define KABI_RENAME(_orig, _new) _new +# define KABI_HIDE_INCLUDE(_file) _file +# define KABI_FAKE_INCLUDE(_file) <linux/kabi.h> +# define KABI_BROKEN_INSERT(_new) _new; +# define KABI_BROKEN_REMOVE(_orig) +# define KABI_BROKEN_INSERT_BLOCK(_new) _new +# define KABI_BROKEN_REMOVE_BLOCK(_orig) +# define KABI_BROKEN_REPLACE(_orig, _new) _new; +# define KABI_BROKEN_INSERT_ENUM(_new) _new, +# define KABI_BROKEN_REMOVE_ENUM(_orig) +# define KABI_EXTEND_ENUM(_new) _new, + +#if IS_BUILTIN(CONFIG_KABI_SIZE_ALIGN_CHECKS) +# define __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) KABI_ALIGN_WARNING); \ + _Static_assert(__alignof__(struct{_new;}) <= __alignof__(struct{_orig;}), \ + __FILE__ ":" __stringify(__LINE__) ": " __stringify(_orig) " is not aligned the same as " __stringify(_new) KABI_ALIGN_WARNING); \ + } +# define __ABI_CHECK_SIZE(_item, _size) \ + _Static_assert(sizeof(struct{_item;}) <= _size, \ + __FILE__ ":" __stringify(__LINE__) ": " __stringify(_item) " is larger than the reserved size (" __stringify(_size) " bytes)" KABI_ALIGN_WARNING) +#else +# define __KABI_CHECK_SIZE_ALIGN(_orig, _new) +# define __KABI_CHECK_SIZE(_item, _size) +#endif + +# define _KABI_DEPRECATE(_type, _orig) _type kabi_reserved_##_orig +# define _KABI_DEPRECATE_FN(_type, _orig, _args...) \ + _type (* kabi_reserved_##_orig)(_args) +# define _KABI_REPLACE(_orig, _new) \ + union { \ + _new; \ + struct { \ + _orig; \ + } __UNIQUE_ID(kabi_hide); \ + __KABI_CHECK_SIZE_ALIGN(_orig, _new); \ + } + +# define _KABI_EXCLUDE(_elem) _elem + +#endif /* __GENKSYMS__ */ + +/* semicolon added wrappers for the KABI_REPLACE macros */ +# define KABI_DEPRECATE(_type, _orig) _KABI_DEPRECATE(_type, _orig); +# define KABI_DEPRECATE_FN(_type, _orig, _args...) \ + _KABI_DEPRECATE_FN(_type, _orig, _args); +# define KABI_REPLACE(_orig, _new) _KABI_REPLACE(_orig, _new); +/* + * Macro for breaking up a random element into two smaller chunks using an + * anonymous struct inside an anonymous union. + */ +# define KABI_REPLACE2(orig, _new1, _new2) KABI_REPLACE(orig, struct{ _new1; _new2;}) + +/* + * We tried to standardize on openEuler reserved names. These wrappers + * leverage those common names making it easier to read and find in the + * code. + */ +# define _KABI_RESERVE(n) unsigned long kabi_reserved##n +# define KABI_RESERVE(n) _KABI_RESERVE(n); +/* + * Simple wrappers to replace standard openEuler reserved elements. + */ +# define KABI_USE(n, _new) KABI_REPLACE(_KABI_RESERVE(n), _new) +/* + * Macros for breaking up a reserved element into two smaller chunks using + * an anonymous struct inside an anonymous union. + */ +# define KABI_USE2(n, _new1, _new2) KABI_REPLACE(_KABI_RESERVE(n), struct{ _new1; _new2; }) + +#define KABI_EXCLUDE(_elem) _KABI_EXCLUDE(_elem); + +#define KABI_EXTEND_WITH_SIZE(_new, _size) \ + KABI_EXTEND(union { \ + _new; \ + unsigned long KABI_UNIQUE_ID[_size]; \ + __KABI_CHECK_SIZE(_new, 8 * (_size)); \ + }) + +#define _KABI_AUX_PTR(_struct) \ + size_t _struct##_size_rh; \ + _KABI_EXCLUDE(struct _struct##_rh *_rh) +#define KABI_AUX_PTR(_struct) \ + _KABI_AUX_PTR(_struct); + +#define _KABI_AUX_EMBED(_struct) \ + size_t _struct##_size_rh; \ + _KABI_EXCLUDE(struct _struct##_rh _rh) +#define KABI_AUX_EMBED(_struct) \ + _KABI_AUX_EMBED(_struct); + +#define KABI_USE_AUX_PTR(n1, n2, _struct) \ + KABI_USE(n1, n2, \ + struct { KABI_AUX_PTR(_struct) }) + +/* + * KABI_AUX_SET_SIZE calculates and sets the size of the extended struct and + * stores it in the size_rh field for structs that are dynamically allocated. + * This macro MUST be called when expanding a base struct with + * KABI_SIZE_AND_EXTEND, and it MUST be called from the allocation site + * regardless of being allocated in the kernel or a module. + * Note: since this macro is intended to be invoked outside of a struct, + * a semicolon is necessary at the end of the line where it is invoked. + */ +#define KABI_AUX_SET_SIZE(_name, _struct) ({ \ + (_name)->_struct##_size_rh = sizeof(struct _struct##_rh); \ +}) + +/* + * KABI_AUX_INIT_SIZE calculates and sets the size of the extended struct and + * stores it in the size_rh field for structs that are statically allocated. + * This macro MUST be called when expanding a base struct with + * KABI_SIZE_AND_EXTEND, and it MUST be called from the declaration site + * regardless of being allocated in the kernel or a module. + */ +#define KABI_AUX_INIT_SIZE(_struct) \ + ._struct##_size_rh = sizeof(struct _struct##_rh), + +/* + * KABI_AUX verifies allocated memory exists. This MUST be called to + * verify that memory in the _rh struct is valid, and can be called + * regardless if KABI_SIZE_AND_EXTEND or KABI_SIZE_AND_EXTEND_PTR is + * used. + */ +#define KABI_AUX(_ptr, _struct, _field) ({ \ + size_t __off = offsetof(struct _struct##_rh, _field); \ + (_ptr)->_struct##_size_rh > __off ? true : false; \ +}) + +#endif /* _LINUX_KABI_H */