whiterose

linux unikernel
Log | Files | Refs | README | LICENSE | git clone https://git.ne02ptzero.me/git/whiterose

commit e468f5c06b5ebef3f6f3c187e51aa6daab667e57
parent baa888d25ea64d0c59344d474284ca99cfdd449a
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date:   Thu,  1 Nov 2018 18:34:46 -0700

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

Diffstat:
MDocumentation/process/index.rst | 1+
ADocumentation/process/programming-language.rst | 45+++++++++++++++++++++++++++++++++++++++++++++
MMAINTAINERS | 5+++++
Mdrivers/auxdisplay/panel.c | 7+++----
Mfs/ext4/ext4.h | 9---------
Minclude/linux/compiler-clang.h | 5-----
Minclude/linux/compiler-gcc.h | 75+++++++--------------------------------------------------------------------
Minclude/linux/compiler-intel.h | 9---------
Minclude/linux/compiler.h | 24+++++++++++++-----------
Ainclude/linux/compiler_attributes.h | 258+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Minclude/linux/compiler_types.h | 100++++++++++++-------------------------------------------------------------------
Mscripts/Makefile.extrawarn | 1+
12 files changed, 348 insertions(+), 191 deletions(-)

diff --git a/Documentation/process/index.rst b/Documentation/process/index.rst @@ -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 diff --git a/Documentation/process/programming-language.rst b/Documentation/process/programming-language.rst @@ -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 + diff --git a/MAINTAINERS b/MAINTAINERS @@ -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/ diff --git a/drivers/auxdisplay/panel.c b/drivers/auxdisplay/panel.c @@ -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; }; diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h @@ -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 */ diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h @@ -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__))) diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h @@ -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)) @@ -131,32 +113,6 @@ #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: * * http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670 @@ -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. diff --git a/include/linux/compiler-intel.h b/include/linux/compiler-intel.h @@ -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)) diff --git a/include/linux/compiler.h b/include/linux/compiler.h @@ -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 */ diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h @@ -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 */ diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h @@ -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 /* @@ -231,23 +175,11 @@ 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 * -Wunused-function. This turns out to avoid the need for complex #ifdef @@ -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 diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn @@ -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)