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authorLinus Torvalds <torvalds@linux-foundation.org>2018-11-01 18:34:46 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-11-01 18:34:46 -0700
commite468f5c06b5ebef3f6f3c187e51aa6daab667e57 (patch)
treebe59927a66ffdf5dec86154a2ccb4ea51602450e
parentbaa888d25ea64d0c59344d474284ca99cfdd449a (diff)
parent1ff2fea5e30ca15752777441ecb64a169fe22e9e (diff)
downloadlinux-e468f5c06b5ebef3f6f3c187e51aa6daab667e57.tar.gz
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
-rw-r--r--Documentation/process/index.rst1
-rw-r--r--Documentation/process/programming-language.rst45
-rw-r--r--MAINTAINERS5
-rw-r--r--drivers/auxdisplay/panel.c7
-rw-r--r--fs/ext4/ext4.h9
-rw-r--r--include/linux/compiler-clang.h5
-rw-r--r--include/linux/compiler-gcc.h75
-rw-r--r--include/linux/compiler-intel.h9
-rw-r--r--include/linux/compiler.h24
-rw-r--r--include/linux/compiler_attributes.h258
-rw-r--r--include/linux/compiler_types.h100
-rw-r--r--scripts/Makefile.extrawarn1
12 files changed, 348 insertions, 191 deletions
diff --git a/Documentation/process/index.rst b/Documentation/process/index.rst
index 757808526d9a..878ebfda7eef 100644
--- 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
new file mode 100644
index 000000000000..e5f5f065dc24
--- /dev/null
+++ 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
index bb97067d0568..f4855974f325 100644
--- 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
index 3b25a643058c..21b9b2f2470a 100644
--- 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
index 12f90d48ba61..3f89d0ab08fc 100644
--- 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
index b1ce500fe8b3..3e7dafb3ea80 100644
--- 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
index 90ddfefb6c2b..c0f5db3a9621 100644
--- 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
index 4c7f9befa9f6..517bd14e1222 100644
--- 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
index 4170fcee5adb..18c80cfa4fc4 100644
--- 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
new file mode 100644
index 000000000000..6b28c1b7310c
--- /dev/null
+++ 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
index 97cfe29b3f0a..3439d7d0249a 100644
--- 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
index 24b2fb1d1297..cf6cd0ef6975 100644
--- 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)