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linux-next/include/linux/compiler_attributes.h
Jan Hendrik Farr f06e108a3d Compiler Attributes: disable __counted_by for clang < 19.1.3 
This patch disables __counted_by for clang versions < 19.1.3 because
of the two issues listed below. It does this by introducing
CONFIG_CC_HAS_COUNTED_BY.

1. clang < 19.1.2 has a bug that can lead to __bdos returning 0:
https://github.com/llvm/llvm-project/pull/110497

2. clang < 19.1.3 has a bug that can lead to __bdos being off by 4:
https://github.com/llvm/llvm-project/pull/112636

Fixes: c8248faf3c ("Compiler Attributes: counted_by: Adjust name and identifier expansion")
Cc: stable@vger.kernel.org # 6.6.x: 16c31dd7fd: Compiler Attributes: counted_by: bump min gcc version
Cc: stable@vger.kernel.org # 6.6.x: 2993eb7a8d: Compiler Attributes: counted_by: fixup clang URL
Cc: stable@vger.kernel.org # 6.6.x: 231dc3f0c9: lkdtm/bugs: Improve warning message for compilers without counted_by support
Cc: stable@vger.kernel.org # 6.6.x
Reported-by: Nathan Chancellor <nathan@kernel.org>
Closes: https://lore.kernel.org/all/20240913164630.GA4091534@thelio-3990X/
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202409260949.a1254989-oliver.sang@intel.com
Link: https://lore.kernel.org/all/Zw8iawAF5W2uzGuh@archlinux/T/#m204c09f63c076586a02d194b87dffc7e81b8de7b
Suggested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Jan Hendrik Farr <kernel@jfarr.cc>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Miguel Ojeda <ojeda@kernel.org>
Reviewed-by: Thorsten Blum <thorsten.blum@linux.dev>
Link: https://lore.kernel.org/r/20241029140036.577804-2-kernel@jfarr.cc
Signed-off-by: Kees Cook <kees@kernel.org>
2024-11-19 08:48:27 -08:00

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/* 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), unless one of the compilers does not support
* the attribute. In that case, __has_attribute is used to check for support
* and the reason is stated in its comment ("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).
* The intention is to keep this file as simple as possible, as well as
* compiler- and version-agnostic (e.g. avoiding GCC_VERSION checks).
*
* 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.
* Provide links to the documentation of each supported compiler, if it exists.
*/
/*
* 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: do not use this directly. Instead, use __alloc_size() since it is conditionally
* available and includes other attributes. For GCC < 9.1, __alloc_size__ gets undefined
* in compiler-gcc.h, due to misbehaviors.
*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-alloc_005fsize-function-attribute
* clang: https://clang.llvm.org/docs/AttributeReference.html#alloc-size
*/
#define __alloc_size__(x, ...) __attribute__((__alloc_size__(x, ## __VA_ARGS__)))
/*
* 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;').
*
* 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
*/
#define __assume_aligned(a, ...) __attribute__((__assume_aligned__(a, ## __VA_ARGS__)))
/*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-cleanup-variable-attribute
* clang: https://clang.llvm.org/docs/AttributeReference.html#cleanup
*/
#define __cleanup(func) __attribute__((__cleanup__(func)))
/*
* Note the long name.
*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-const-function-attribute
*/
#define __attribute_const__ __attribute__((__const__))
/*
* Optional: only supported since gcc >= 9
* Optional: not supported by clang
*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-copy-function-attribute
*/
#if __has_attribute(__copy__)
# define __copy(symbol) __attribute__((__copy__(symbol)))
#else
# define __copy(symbol)
#endif
/*
* Optional: not supported by gcc
* Optional: only supported since clang >= 14.0
*
* clang: https://clang.llvm.org/docs/AttributeReference.html#diagnose_as_builtin
*/
#if __has_attribute(__diagnose_as_builtin__)
# define __diagnose_as(builtin...) __attribute__((__diagnose_as_builtin__(builtin)))
#else
# define __diagnose_as(builtin...)
#endif
/*
* 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: not supported by clang
*
* 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: only supported since clang >= 14.0
*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-error-function-attribute
*/
#if __has_attribute(__error__)
# define __compiletime_error(msg) __attribute__((__error__(msg)))
#else
# define __compiletime_error(msg)
#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
* clang: https://clang.llvm.org/docs/AttributeReference.html#malloc
*/
#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: only supported since gcc >= 7
*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/x86-Function-Attributes.html#index-no_005fcaller_005fsaved_005fregisters-function-attribute_002c-x86
* clang: https://clang.llvm.org/docs/AttributeReference.html#no-caller-saved-registers
*/
#if __has_attribute(__no_caller_saved_registers__)
# define __no_caller_saved_registers __attribute__((__no_caller_saved_registers__))
#else
# define __no_caller_saved_registers
#endif
/*
* Optional: not supported by clang
*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noclone-function-attribute
*/
#if __has_attribute(__noclone__)
# define __noclone __attribute__((__noclone__))
#else
# define __noclone
#endif
/*
* Add the pseudo keyword 'fallthrough' so case statement blocks
* must end with any of these keywords:
* break;
* fallthrough;
* continue;
* goto <label>;
* return [expression];
*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Statement-Attributes.html#Statement-Attributes
*/
#if __has_attribute(__fallthrough__)
# define fallthrough __attribute__((__fallthrough__))
#else
# define fallthrough do {} while (0) /* fallthrough */
#endif
/*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#Common-Function-Attributes
* clang: https://clang.llvm.org/docs/AttributeReference.html#flatten
*/
# define __flatten __attribute__((flatten))
/*
* 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
*
* 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
/*
* Optional: only supported since GCC >= 7.1, clang >= 13.0.
*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-no_005fprofile_005finstrument_005ffunction-function-attribute
* clang: https://clang.llvm.org/docs/AttributeReference.html#no-profile-instrument-function
*/
#if __has_attribute(__no_profile_instrument_function__)
# define __no_profile __attribute__((__no_profile_instrument_function__))
#else
# define __no_profile
#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 >= 11.1, clang >= 7.0.
*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-no_005fstack_005fprotector-function-attribute
* clang: https://clang.llvm.org/docs/AttributeReference.html#no-stack-protector-safebuffers
*/
#if __has_attribute(__no_stack_protector__)
# define __no_stack_protector __attribute__((__no_stack_protector__))
#else
# define __no_stack_protector
#endif
/*
* Optional: not supported by gcc.
*
* clang: https://clang.llvm.org/docs/AttributeReference.html#overloadable
*/
#if __has_attribute(__overloadable__)
# define __overloadable __attribute__((__overloadable__))
#else
# define __overloadable
#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__))
/*
* Note: the "type" argument should match any __builtin_object_size(p, type) usage.
*
* Optional: not supported by gcc.
*
* clang: https://clang.llvm.org/docs/AttributeReference.html#pass-object-size-pass-dynamic-object-size
*/
#if __has_attribute(__pass_dynamic_object_size__)
# define __pass_dynamic_object_size(type) __attribute__((__pass_dynamic_object_size__(type)))
#else
# define __pass_dynamic_object_size(type)
#endif
#if __has_attribute(__pass_object_size__)
# define __pass_object_size(type) __attribute__((__pass_object_size__(type)))
#else
# define __pass_object_size(type)
#endif
/*
* 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(section) __attribute__((__section__(section)))
/*
* Optional: only supported since gcc >= 12
*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-uninitialized-variable-attribute
* clang: https://clang.llvm.org/docs/AttributeReference.html#uninitialized
*/
#if __has_attribute(__uninitialized__)
# define __uninitialized __attribute__((__uninitialized__))
#else
# define __uninitialized
#endif
/*
* 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__))
/*
* The __used attribute guarantees that the attributed variable will be
* always emitted by a compiler. It doesn't prevent the compiler from
* throwing 'unused' warnings when it can't detect how the variable is
* actually used. It's a compiler implementation details either emit
* the warning in that case or not.
*
* The combination of both 'used' and 'unused' attributes ensures that
* the variable would be emitted, and will not trigger 'unused' warnings.
* The attribute is applicable for functions, static and global variables.
*/
#define __always_used __used __maybe_unused
/*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-warn_005funused_005fresult-function-attribute
* clang: https://clang.llvm.org/docs/AttributeReference.html#nodiscard-warn-unused-result
*/
#define __must_check __attribute__((__warn_unused_result__))
/*
* Optional: only supported since clang >= 14.0
*
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-warning-function-attribute
*/
#if __has_attribute(__warning__)
# define __compiletime_warning(msg) __attribute__((__warning__(msg)))
#else
# define __compiletime_warning(msg)
#endif
/*
* Optional: only supported since clang >= 14.0
*
* clang: https://clang.llvm.org/docs/AttributeReference.html#disable-sanitizer-instrumentation
*
* disable_sanitizer_instrumentation is not always similar to
* no_sanitize((<sanitizer-name>)): the latter may still let specific sanitizers
* insert code into functions to prevent false positives. Unlike that,
* disable_sanitizer_instrumentation prevents all kinds of instrumentation to
* functions with the attribute.
*/
#if __has_attribute(disable_sanitizer_instrumentation)
# define __disable_sanitizer_instrumentation \
__attribute__((disable_sanitizer_instrumentation))
#else
# define __disable_sanitizer_instrumentation
#endif
/*
* 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__))
/*
* Used by functions that use '__builtin_return_address'. These function
* don't want to be splited or made inline, which can make
* the '__builtin_return_address' get unexpected address.
*/
#define __fix_address noinline __noclone
#endif /* __LINUX_COMPILER_ATTRIBUTES_H */
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