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The Compiler Attributes series

Browse Source 
This is an effort to disentangle the include/linux/compiler*.h headers
 and bring them up to date.
 
 The main idea behind the series is to use feature checking macros
 (i.e. __has_attribute) instead of compiler version checks (e.g. GCC_VERSION),
 which are compiler-agnostic (so they can be shared, reducing the size
 of compiler-specific headers) and version-agnostic.
 
 Other related improvements have been performed in the headers as well,
 which on top of the use of __has_attribute it has amounted to a significant
 simplification of these headers (e.g. GCC_VERSION is now only guarding
 a few non-attribute macros).
 
 This series should also help the efforts to support compiling the kernel
 with clang and icc. A fair amount of documentation and comments have also
 been added, clarified or removed; and the headers are now more readable,
 which should help kernel developers in general.
 
 The series was triggered due to the move to gcc >= 4.6. In turn, this series
 has also triggered Sparse to gain the ability to recognize __has_attribute
 on its own.
 
 Finally, the __nonstring variable attribute series has been also applied
 on top; plus two related patches from Nick Desaulniers for unreachable()
 that came a bit afterwards.
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Merge tag 'compiler-attributes-for-linus-4.20-rc1' of https://github.com/ojeda/linux

Pull compiler attribute updates from Miguel Ojeda:
 "This is an effort to disentangle the include/linux/compiler*.h headers
  and bring them up to date.

  The main idea behind the series is to use feature checking macros
  (i.e. __has_attribute) instead of compiler version checks (e.g.
  GCC_VERSION), which are compiler-agnostic (so they can be shared,
  reducing the size of compiler-specific headers) and version-agnostic.

  Other related improvements have been performed in the headers as well,
  which on top of the use of __has_attribute it has amounted to a
  significant simplification of these headers (e.g. GCC_VERSION is now
  only guarding a few non-attribute macros).

  This series should also help the efforts to support compiling the
  kernel with clang and icc. A fair amount of documentation and comments
  have also been added, clarified or removed; and the headers are now
  more readable, which should help kernel developers in general.

  The series was triggered due to the move to gcc >= 4.6. In turn, this
  series has also triggered Sparse to gain the ability to recognize
  __has_attribute on its own.

  Finally, the __nonstring variable attribute series has been also
  applied on top; plus two related patches from Nick Desaulniers for
  unreachable() that came a bit afterwards"

* tag 'compiler-attributes-for-linus-4.20-rc1' of https://github.com/ojeda/linux:
  compiler-gcc: remove comment about gcc 4.5 from unreachable()
  compiler.h: update definition of unreachable()
  Compiler Attributes: ext4: remove local __nonstring definition
  Compiler Attributes: auxdisplay: panel: use __nonstring
  Compiler Attributes: enable -Wstringop-truncation on W=1 (gcc >= 8)
  Compiler Attributes: add support for __nonstring (gcc >= 8)
  Compiler Attributes: add MAINTAINERS entry
  Compiler Attributes: add Doc/process/programming-language.rst
  Compiler Attributes: remove uses of __attribute__ from compiler.h
  Compiler Attributes: KENTRY used twice the "used" attribute
  Compiler Attributes: use feature checks instead of version checks
  Compiler Attributes: add missing SPDX ID in compiler_types.h
  Compiler Attributes: remove unneeded sparse (__CHECKER__) tests
  Compiler Attributes: homogenize __must_be_array
  Compiler Attributes: remove unneeded tests
  Compiler Attributes: always use the extra-underscores syntax
  Compiler Attributes: remove unused attributes
This commit is contained in:
Linus Torvalds 2018-11-01 18:34:46 -07:00
commit e468f5c06b
12 changed files with 348 additions and 191 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
Documentation/process/index.rst
View File

@ -25,6 +25,7 @@ Below are the essential guides that every developer should read.
code-of-conduct-interpretation
development-process
submitting-patches
programming-language
coding-style
maintainer-pgp-guide
email-clients

45
Documentation/process/programming-language.rst Normal file
View File

@ -0,0 +1,45 @@
.. _programming_language:
Programming Language
====================
The kernel is written in the C programming language [c-language]_.
More precisely, the kernel is typically compiled with ``gcc`` [gcc]_
under ``-std=gnu89`` [gcc-c-dialect-options]_: the GNU dialect of ISO C90
(including some C99 features).
This dialect contains many extensions to the language [gnu-extensions]_,
and many of them are used within the kernel as a matter of course.
There is some support for compiling the kernel with ``clang`` [clang]_
and ``icc`` [icc]_ for several of the architectures, although at the time
of writing it is not completed, requiring third-party patches.
Attributes
----------
One of the common extensions used throughout the kernel are attributes
[gcc-attribute-syntax]_. Attributes allow to introduce
implementation-defined semantics to language entities (like variables,
functions or types) without having to make significant syntactic changes
to the language (e.g. adding a new keyword) [n2049]_.
In some cases, attributes are optional (i.e. a compiler not supporting them
should still produce proper code, even if it is slower or does not perform
as many compile-time checks/diagnostics).
The kernel defines pseudo-keywords (e.g. ``__pure``) instead of using
directly the GNU attribute syntax (e.g. ``__attribute__((__pure__))``)
in order to feature detect which ones can be used and/or to shorten the code.
Please refer to ``include/linux/compiler_attributes.h`` for more information.
.. [c-language] http://www.open-std.org/jtc1/sc22/wg14/www/standards
.. [gcc] https://gcc.gnu.org
.. [clang] https://clang.llvm.org
.. [icc] https://software.intel.com/en-us/c-compilers
.. [gcc-c-dialect-options] https://gcc.gnu.org/onlinedocs/gcc/C-Dialect-Options.html
.. [gnu-extensions] https://gcc.gnu.org/onlinedocs/gcc/C-Extensions.html
.. [gcc-attribute-syntax] https://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html
.. [n2049] http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2049.pdf

5
MAINTAINERS
View File

@ -3737,6 +3737,11 @@ L: platform-driver-x86@vger.kernel.org
S: Maintained
F: drivers/platform/x86/compal-laptop.c
COMPILER ATTRIBUTES
M: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
S: Maintained
F: include/linux/compiler_attributes.h
CONEXANT ACCESSRUNNER USB DRIVER
L: accessrunner-general@lists.sourceforge.net
W: http://accessrunner.sourceforge.net/

7
drivers/auxdisplay/panel.c
View File

@ -155,10 +155,9 @@ struct logical_input {
int release_data;
} std;
struct { /* valid when type == INPUT_TYPE_KBD */
/* strings can be non null-terminated */
char press_str[sizeof(void *) + sizeof(int)];
char repeat_str[sizeof(void *) + sizeof(int)];
char release_str[sizeof(void *) + sizeof(int)];
char press_str[sizeof(void *) + sizeof(int)] __nonstring;
char repeat_str[sizeof(void *) + sizeof(int)] __nonstring;
char release_str[sizeof(void *) + sizeof(int)] __nonstring;
} kbd;
} u;
};

9
fs/ext4/ext4.h
View File

@ -45,15 +45,6 @@
#include <linux/compiler.h>
/* Until this gets included into linux/compiler-gcc.h */
#ifndef __nonstring
#if defined(GCC_VERSION) && (GCC_VERSION >= 80000)
#define __nonstring __attribute__((nonstring))
#else
#define __nonstring
#endif
#endif
/*
* The fourth extended filesystem constants/structures
*/

5
include/linux/compiler-clang.h
View File

@ -21,8 +21,6 @@
#define __SANITIZE_ADDRESS__
#endif
#define __no_sanitize_address __attribute__((no_sanitize("address")))
/*
* Not all versions of clang implement the the type-generic versions
* of the builtin overflow checkers. Fortunately, clang implements
@ -41,6 +39,3 @@
* compilers, like ICC.
*/
#define barrier() __asm__ __volatile__("" : : : "memory")
#define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
#define __assume_aligned(a, ...) \
__attribute__((__assume_aligned__(a, ## __VA_ARGS__)))

75
include/linux/compiler-gcc.h
View File

@ -68,31 +68,20 @@
*/
#define uninitialized_var(x) x = x
#ifdef __CHECKER__
#define __must_be_array(a) 0
#else
/* &a[0] degrades to a pointer: a different type from an array */
#define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
#endif
#ifdef RETPOLINE
#define __noretpoline __attribute__((indirect_branch("keep")))
#define __noretpoline __attribute__((__indirect_branch__("keep")))
#endif
#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
#define __optimize(level) __attribute__((__optimize__(level)))
#define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
#ifndef __CHECKER__
#define __compiletime_warning(message) __attribute__((warning(message)))
#define __compiletime_error(message) __attribute__((error(message)))
#define __compiletime_warning(message) __attribute__((__warning__(message)))
#define __compiletime_error(message) __attribute__((__error__(message)))
#ifdef LATENT_ENTROPY_PLUGIN
#if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__)
#define __latent_entropy __attribute__((latent_entropy))
#endif
#endif /* __CHECKER__ */
/*
* calling noreturn functions, __builtin_unreachable() and __builtin_trap()
@ -107,10 +96,6 @@
* Mark a position in code as unreachable. This can be used to
* suppress control flow warnings after asm blocks that transfer
* control elsewhere.
*
* Early snapshots of gcc 4.5 don't support this and we can't detect
* this in the preprocessor, but we can live with this because they're
* unreleased. Really, we need to have autoconf for the kernel.
*/
#define unreachable() \
do { \
@ -119,9 +104,6 @@
__builtin_unreachable(); \
} while (0)
/* Mark a function definition as prohibited from being cloned. */
#define __noclone __attribute__((__noclone__, __optimize__("no-tracer")))
#if defined(RANDSTRUCT_PLUGIN) && !defined(__CHECKER__)
#define __randomize_layout __attribute__((randomize_layout))
#define __no_randomize_layout __attribute__((no_randomize_layout))
@ -130,32 +112,6 @@
#define randomized_struct_fields_end } __randomize_layout;
#endif
/*
* When used with Link Time Optimization, gcc can optimize away C functions or
* variables which are referenced only from assembly code. __visible tells the
* optimizer that something else uses this function or variable, thus preventing
* this.
*/
#define __visible __attribute__((externally_visible))
/* gcc version specific checks */
#if GCC_VERSION >= 40900 && !defined(__CHECKER__)
/*
* __assume_aligned(n, k): Tell the optimizer that the returned
* pointer can be assumed to be k modulo n. The second argument is
* optional (default 0), so we use a variadic macro to make the
* shorthand.
*
* Beware: Do not apply this to functions which may return
* ERR_PTRs. Also, it is probably unwise to apply it to functions
* returning extra information in the low bits (but in that case the
* compiler should see some alignment anyway, when the return value is
* massaged by 'flags = ptr & 3; ptr &= ~3;').
*/
#define __assume_aligned(a, ...) __attribute__((__assume_aligned__(a, ## __VA_ARGS__)))
#endif
/*
* GCC 'asm goto' miscompiles certain code sequences:
*
@ -187,39 +143,22 @@
#define KASAN_ABI_VERSION 3
#endif
#if GCC_VERSION >= 40902
/*
* Tell the compiler that address safety instrumentation (KASAN)
* should not be applied to that function.
* Conflicts with inlining: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368
* Because __no_sanitize_address conflicts with inlining:
* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368
* we do one or the other.
*/
#define __no_sanitize_address __attribute__((no_sanitize_address))
#ifdef CONFIG_KASAN
#define __no_sanitize_address_or_inline \
__no_sanitize_address __maybe_unused notrace
#else
#define __no_sanitize_address_or_inline inline
#endif
#endif
#if GCC_VERSION >= 50100
/*
* Mark structures as requiring designated initializers.
* https://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html
*/
#define __designated_init __attribute__((designated_init))
#define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1
#endif
#if !defined(__noclone)
#define __noclone /* not needed */
#endif
#if !defined(__no_sanitize_address)
#define __no_sanitize_address
#define __no_sanitize_address_or_inline inline
#endif
/*
* Turn individual warnings and errors on and off locally, depending
* on version.

9
include/linux/compiler-intel.h
View File

@ -29,17 +29,8 @@
*/
#define OPTIMIZER_HIDE_VAR(var) barrier()
/* Intel ECC compiler doesn't support __builtin_types_compatible_p() */
#define __must_be_array(a) 0
#endif
/* icc has this, but it's called _bswap16 */
#define __HAVE_BUILTIN_BSWAP16__
#define __builtin_bswap16 _bswap16
/* The following are for compatibility with GCC, from compiler-gcc.h,
* and may be redefined here because they should not be shared with other
* compilers, like clang.
*/
#define __visible __attribute__((externally_visible))

24
include/linux/compiler.h
View File

@ -23,8 +23,8 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
#define __branch_check__(x, expect, is_constant) ({ \
long ______r; \
static struct ftrace_likely_data \
__attribute__((__aligned__(4))) \
__attribute__((section("_ftrace_annotated_branch"))) \
__aligned(4) \
__section("_ftrace_annotated_branch") \
______f = { \
.data.func = __func__, \
.data.file = __FILE__, \
@ -59,8 +59,8 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
({ \
int ______r; \
static struct ftrace_branch_data \
__attribute__((__aligned__(4))) \
__attribute__((section("_ftrace_branch"))) \
__aligned(4) \
__section("_ftrace_branch") \
______f = { \
.func = __func__, \
.file = __FILE__, \
@ -115,7 +115,10 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
# define ASM_UNREACHABLE
#endif
#ifndef unreachable
# define unreachable() do { annotate_reachable(); do { } while (1); } while (0)
# define unreachable() do { \
annotate_unreachable(); \
__builtin_unreachable(); \
} while (0)
#endif
/*
@ -137,7 +140,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
extern typeof(sym) sym; \
static const unsigned long __kentry_##sym \
__used \
__attribute__((section("___kentry" "+" #sym ), used)) \
__section("___kentry" "+" #sym ) \
= (unsigned long)&sym;
#endif
@ -278,7 +281,7 @@ unsigned long read_word_at_a_time(const void *addr)
* visible to the compiler.
*/
#define __ADDRESSABLE(sym) \
static void * __attribute__((section(".discard.addressable"), used)) \
static void * __section(".discard.addressable") __used \
__PASTE(__addressable_##sym, __LINE__) = (void *)&sym;
/**
@ -331,10 +334,6 @@ static inline void *offset_to_ptr(const int *off)
#endif /* __KERNEL__ */
#endif /* __ASSEMBLY__ */
#ifndef __optimize
# define __optimize(level)
#endif
/* Compile time object size, -1 for unknown */
#ifndef __compiletime_object_size
# define __compiletime_object_size(obj) -1
@ -376,4 +375,7 @@ static inline void *offset_to_ptr(const int *off)
compiletime_assert(__native_word(t), \
"Need native word sized stores/loads for atomicity.")
/* &a[0] degrades to a pointer: a different type from an array */
#define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
#endif /* __LINUX_COMPILER_H */

258
include/linux/compiler_attributes.h Normal file
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@ -0,0 +1,258 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __LINUX_COMPILER_ATTRIBUTES_H
#define __LINUX_COMPILER_ATTRIBUTES_H
/*
* The attributes in this file are unconditionally defined and they directly
* map to compiler attribute(s) -- except those that are optional.
*
* Any other "attributes" (i.e. those that depend on a configuration option,
* on a compiler, on an architecture, on plugins, on other attributes...)
* should be defined elsewhere (e.g. compiler_types.h or compiler-*.h).
*
* This file is meant to be sorted (by actual attribute name,
* not by #define identifier). Use the __attribute__((__name__)) syntax
* (i.e. with underscores) to avoid future collisions with other macros.
* If an attribute is optional, state the reason in the comment.
*/
/*
* To check for optional attributes, we use __has_attribute, which is supported
* on gcc >= 5, clang >= 2.9 and icc >= 17. In the meantime, to support
* 4.6 <= gcc < 5, we implement __has_attribute by hand.
*
* sparse does not support __has_attribute (yet) and defines __GNUC_MINOR__
* depending on the compiler used to build it; however, these attributes have
* no semantic effects for sparse, so it does not matter. Also note that,
* in order to avoid sparse's warnings, even the unsupported ones must be
* defined to 0.
*/
#ifndef __has_attribute
# define __has_attribute(x) __GCC4_has_attribute_##x
# define __GCC4_has_attribute___assume_aligned__ (__GNUC_MINOR__ >= 9)
# define __GCC4_has_attribute___designated_init__ 0
# define __GCC4_has_attribute___externally_visible__ 1
# define __GCC4_has_attribute___noclone__ 1
# define __GCC4_has_attribute___optimize__ 1
# define __GCC4_has_attribute___nonstring__ 0
# define __GCC4_has_attribute___no_sanitize_address__ (__GNUC_MINOR__ >= 8)
#endif
/*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-alias-function-attribute
*/
#define __alias(symbol) __attribute__((__alias__(#symbol)))
/*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-aligned-function-attribute
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-aligned-type-attribute
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-aligned-variable-attribute
*/
#define __aligned(x) __attribute__((__aligned__(x)))
#define __aligned_largest __attribute__((__aligned__))
/*
* Note: users of __always_inline currently do not write "inline" themselves,
* which seems to be required by gcc to apply the attribute according
* to its docs (and also "warning: always_inline function might not be
* inlinable [-Wattributes]" is emitted).
*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-always_005finline-function-attribute
* clang: mentioned
*/
#define __always_inline inline __attribute__((__always_inline__))
/*
* The second argument is optional (default 0), so we use a variadic macro
* to make the shorthand.
*
* Beware: Do not apply this to functions which may return
* ERR_PTRs. Also, it is probably unwise to apply it to functions
* returning extra information in the low bits (but in that case the
* compiler should see some alignment anyway, when the return value is
* massaged by 'flags = ptr & 3; ptr &= ~3;').
*
* Optional: only supported since gcc >= 4.9
* Optional: not supported by icc
*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-assume_005faligned-function-attribute
* clang: https://clang.llvm.org/docs/AttributeReference.html#assume-aligned
*/
#if __has_attribute(__assume_aligned__)
# define __assume_aligned(a, ...) __attribute__((__assume_aligned__(a, ## __VA_ARGS__)))
#else
# define __assume_aligned(a, ...)
#endif
/*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-cold-function-attribute
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Label-Attributes.html#index-cold-label-attribute
*/
#define __cold __attribute__((__cold__))
/*
* Note the long name.
*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-const-function-attribute
*/
#define __attribute_const__ __attribute__((__const__))
/*
* Don't. Just don't. See commit 771c035372a0 ("deprecate the '__deprecated'
* attribute warnings entirely and for good") for more information.
*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-deprecated-function-attribute
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-deprecated-type-attribute
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-deprecated-variable-attribute
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Enumerator-Attributes.html#index-deprecated-enumerator-attribute
* clang: https://clang.llvm.org/docs/AttributeReference.html#deprecated
*/
#define __deprecated
/*
* Optional: only supported since gcc >= 5.1
* Optional: not supported by clang
* Optional: not supported by icc
*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-designated_005finit-type-attribute
*/
#if __has_attribute(__designated_init__)
# define __designated_init __attribute__((__designated_init__))
#else
# define __designated_init
#endif
/*
* Optional: not supported by clang
*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-externally_005fvisible-function-attribute
*/
#if __has_attribute(__externally_visible__)
# define __visible __attribute__((__externally_visible__))
#else
# define __visible
#endif
/*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-format-function-attribute
* clang: https://clang.llvm.org/docs/AttributeReference.html#format
*/
#define __printf(a, b) __attribute__((__format__(printf, a, b)))
#define __scanf(a, b) __attribute__((__format__(scanf, a, b)))
/*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-gnu_005finline-function-attribute
* clang: https://clang.llvm.org/docs/AttributeReference.html#gnu-inline
*/
#define __gnu_inline __attribute__((__gnu_inline__))
/*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-malloc-function-attribute
*/
#define __malloc __attribute__((__malloc__))
/*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-mode-type-attribute
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-mode-variable-attribute
*/
#define __mode(x) __attribute__((__mode__(x)))
/*
* Optional: not supported by clang
* Note: icc does not recognize gcc's no-tracer
*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noclone-function-attribute
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-optimize-function-attribute
*/
#if __has_attribute(__noclone__)
# if __has_attribute(__optimize__)
# define __noclone __attribute__((__noclone__, __optimize__("no-tracer")))
# else
# define __noclone __attribute__((__noclone__))
# endif
#else
# define __noclone
#endif
/*
* Note the missing underscores.
*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noinline-function-attribute
* clang: mentioned
*/
#define noinline __attribute__((__noinline__))
/*
* Optional: only supported since gcc >= 8
* Optional: not supported by clang
* Optional: not supported by icc
*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-nonstring-variable-attribute
*/
#if __has_attribute(__nonstring__)
# define __nonstring __attribute__((__nonstring__))
#else
# define __nonstring
#endif
/*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noreturn-function-attribute
* clang: https://clang.llvm.org/docs/AttributeReference.html#noreturn
* clang: https://clang.llvm.org/docs/AttributeReference.html#id1
*/
#define __noreturn __attribute__((__noreturn__))
/*
* Optional: only supported since gcc >= 4.8
* Optional: not supported by icc
*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-no_005fsanitize_005faddress-function-attribute
* clang: https://clang.llvm.org/docs/AttributeReference.html#no-sanitize-address-no-address-safety-analysis
*/
#if __has_attribute(__no_sanitize_address__)
# define __no_sanitize_address __attribute__((__no_sanitize_address__))
#else
# define __no_sanitize_address
#endif
/*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-packed-type-attribute
* clang: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-packed-variable-attribute
*/
#define __packed __attribute__((__packed__))
/*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-pure-function-attribute
*/
#define __pure __attribute__((__pure__))
/*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-section-function-attribute
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-section-variable-attribute
* clang: https://clang.llvm.org/docs/AttributeReference.html#section-declspec-allocate
*/
#define __section(S) __attribute__((__section__(#S)))
/*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-unused-function-attribute
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-unused-type-attribute
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-unused-variable-attribute
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Label-Attributes.html#index-unused-label-attribute
* clang: https://clang.llvm.org/docs/AttributeReference.html#maybe-unused-unused
*/
#define __always_unused __attribute__((__unused__))
#define __maybe_unused __attribute__((__unused__))
/*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-used-function-attribute
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-used-variable-attribute
*/
#define __used __attribute__((__used__))
/*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-weak-function-attribute
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-weak-variable-attribute
*/
#define __weak __attribute__((__weak__))
#endif /* __LINUX_COMPILER_ATTRIBUTES_H */

100
include/linux/compiler_types.h
View File

@ -1,3 +1,4 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __LINUX_COMPILER_TYPES_H
#define __LINUX_COMPILER_TYPES_H
@ -54,6 +55,9 @@ extern void __chk_io_ptr(const volatile void __iomem *);
#ifdef __KERNEL__
/* Attributes */
#include <linux/compiler_attributes.h>
/* Compiler specific macros. */
#ifdef __clang__
#include <linux/compiler-clang.h>
@ -78,12 +82,6 @@ extern void __chk_io_ptr(const volatile void __iomem *);
#include <asm/compiler.h>
#endif
/*
* Generic compiler-independent macros required for kernel
* build go below this comment. Actual compiler/compiler version
* specific implementations come from the above header files
*/
struct ftrace_branch_data {
const char *func;
const char *file;
@ -106,10 +104,6 @@ struct ftrace_likely_data {
unsigned long constant;
};
/* Don't. Just don't. */
#define __deprecated
#define __deprecated_for_modules
#endif /* __KERNEL__ */
#endif /* __ASSEMBLY__ */
@ -119,10 +113,6 @@ struct ftrace_likely_data {
* compilers. We don't consider that to be an error, so set them to nothing.
* For example, some of them are for compiler specific plugins.
*/
#ifndef __designated_init
# define __designated_init
#endif
#ifndef __latent_entropy
# define __latent_entropy
#endif
@ -140,17 +130,6 @@ struct ftrace_likely_data {
# define randomized_struct_fields_end
#endif
#ifndef __visible
#define __visible
#endif
/*
* Assume alignment of return value.
*/
#ifndef __assume_aligned
#define __assume_aligned(a, ...)
#endif
/* Are two types/vars the same type (ignoring qualifiers)? */
#define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
@ -159,14 +138,6 @@ struct ftrace_likely_data {
(sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || \
sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long))
#ifndef __attribute_const__
#define __attribute_const__ __attribute__((__const__))
#endif
#ifndef __noclone
#define __noclone
#endif
/* Helpers for emitting diagnostics in pragmas. */
#ifndef __diag
#define __diag(string)
@ -186,43 +157,16 @@ struct ftrace_likely_data {
#define __diag_error(compiler, version, option, comment) \
__diag_ ## compiler(version, error, option)
/*
* From the GCC manual:
*
* Many functions have no effects except the return value and their
* return value depends only on the parameters and/or global
* variables. Such a function can be subject to common subexpression
* elimination and loop optimization just as an arithmetic operator
* would be.
* [...]
*/
#define __pure __attribute__((pure))
#define __aligned(x) __attribute__((aligned(x)))
#define __printf(a, b) __attribute__((format(printf, a, b)))
#define __scanf(a, b) __attribute__((format(scanf, a, b)))
#define __maybe_unused __attribute__((unused))
#define __always_unused __attribute__((unused))
#define __mode(x) __attribute__((mode(x)))
#define __malloc __attribute__((__malloc__))
#define __used __attribute__((__used__))
#define __noreturn __attribute__((noreturn))
#define __packed __attribute__((packed))
#define __weak __attribute__((weak))
#define __alias(symbol) __attribute__((alias(#symbol)))
#define __cold __attribute__((cold))
#define __section(S) __attribute__((__section__(#S)))
#ifdef CONFIG_ENABLE_MUST_CHECK
#define __must_check __attribute__((warn_unused_result))
#define __must_check __attribute__((__warn_unused_result__))
#else
#define __must_check
#endif
#if defined(CC_USING_HOTPATCH) && !defined(__CHECKER__)
#if defined(CC_USING_HOTPATCH)
#define notrace __attribute__((hotpatch(0, 0)))
#else
#define notrace __attribute__((no_instrument_function))
#define notrace __attribute__((__no_instrument_function__))
#endif
/*
@ -231,22 +175,10 @@ struct ftrace_likely_data {
* stack and frame pointer being set up and there is no chance to
* restore the lr register to the value before mcount was called.
*/
#define __naked __attribute__((naked)) notrace
#define __naked __attribute__((__naked__)) notrace
#define __compiler_offsetof(a, b) __builtin_offsetof(a, b)
/*
* Feature detection for gnu_inline (gnu89 extern inline semantics). Either
* __GNUC_STDC_INLINE__ is defined (not using gnu89 extern inline semantics,
* and we opt in to the gnu89 semantics), or __GNUC_STDC_INLINE__ is not
* defined so the gnu89 semantics are the default.
*/
#ifdef __GNUC_STDC_INLINE__
# define __gnu_inline __attribute__((gnu_inline))
#else
# define __gnu_inline
#endif
/*
* Force always-inline if the user requests it so via the .config.
* GCC does not warn about unused static inline functions for
@ -258,22 +190,20 @@ struct ftrace_likely_data {
* semantics rather than c99. This prevents multiple symbol definition errors
* of extern inline functions at link time.
* A lot of inline functions can cause havoc with function tracing.
* Do not use __always_inline here, since currently it expands to inline again
* (which would break users of __always_inline).
*/
#if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \
!defined(CONFIG_OPTIMIZE_INLINING)
#define inline \
inline __attribute__((always_inline, unused)) notrace __gnu_inline
#define inline inline __attribute__((__always_inline__)) __gnu_inline \
__maybe_unused notrace
#else
#define inline inline __attribute__((unused)) notrace __gnu_inline
#define inline inline __gnu_inline \
__maybe_unused notrace
#endif
#define __inline__ inline
#define __inline inline
#define noinline __attribute__((noinline))
#ifndef __always_inline
#define __always_inline inline __attribute__((always_inline))
#endif
#define __inline inline
/*
* Rather then using noinline to prevent stack consumption, use

1
scripts/Makefile.extrawarn
View File

@ -29,6 +29,7 @@ warning-1 += $(call cc-option, -Wmissing-include-dirs)
warning-1 += $(call cc-option, -Wunused-but-set-variable)
warning-1 += $(call cc-option, -Wunused-const-variable)
warning-1 += $(call cc-option, -Wpacked-not-aligned)
warning-1 += $(call cc-option, -Wstringop-truncation)
warning-1 += $(call cc-disable-warning, missing-field-initializers)
warning-1 += $(call cc-disable-warning, sign-compare)