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![Kees Cook](/assets/img/avatar_default.png)
GCC and Clang can use the "alloc_size" attribute to better inform the results of __builtin_object_size() (for compile-time constant values). Clang can additionally use alloc_size to inform the results of __builtin_dynamic_object_size() (for run-time values). Because GCC sees the frequent use of struct_size() as an allocator size argument, and notices it can return SIZE_MAX (the overflow indication), it complains about these call sites overflowing (since SIZE_MAX is greater than the default -Walloc-size-larger-than=PTRDIFF_MAX). This isn't helpful since we already know a SIZE_MAX will be caught at run-time (this was an intentional design). To deal with this, we must disable this check as it is both a false positive and redundant. (Clang does not have this warning option.) Unfortunately, just checking the -Wno-alloc-size-larger-than is not sufficient to make the __alloc_size attribute behave correctly under older GCC versions. The attribute itself must be disabled in those situations too, as there appears to be no way to reliably silence the SIZE_MAX constant expression cases for GCC versions less than 9.1: In file included from ./include/linux/resource_ext.h:11, from ./include/linux/pci.h:40, from drivers/net/ethernet/intel/ixgbe/ixgbe.h:9, from drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c:4: In function 'kmalloc_node', inlined from 'ixgbe_alloc_q_vector' at ./include/linux/slab.h:743:9: ./include/linux/slab.h:618:9: error: argument 1 value '18446744073709551615' exceeds maximum object size 9223372036854775807 [-Werror=alloc-size-larger-than=] return __kmalloc_node(size, flags, node); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ./include/linux/slab.h: In function 'ixgbe_alloc_q_vector': ./include/linux/slab.h:455:7: note: in a call to allocation function '__kmalloc_node' declared here void *__kmalloc_node(size_t size, gfp_t flags, int node) __assume_slab_alignment __malloc; ^~~~~~~~~~~~~~ Specifically: '-Wno-alloc-size-larger-than' is not correctly handled by GCC < 9.1 https://godbolt.org/z/hqsfG7q84 (doesn't disable) https://godbolt.org/z/P9jdrPTYh (doesn't admit to not knowing about option) https://godbolt.org/z/465TPMWKb (only warns when other warnings appear) '-Walloc-size-larger-than=18446744073709551615' is not handled by GCC < 8.2 https://godbolt.org/z/73hh1EPxz (ignores numeric value) Since anything marked with __alloc_size would also qualify for marking with __malloc, just include __malloc along with it to avoid redundant markings. (Suggested by Linus Torvalds.) Finally, make sure checkpatch.pl doesn't get confused about finding the __alloc_size attribute on functions. (Thanks to Joe Perches.) Link: https://lkml.kernel.org/r/20210930222704.2631604-3-keescook@chromium.org Signed-off-by: Kees Cook <keescook@chromium.org> Tested-by: Randy Dunlap <rdunlap@infradead.org> Cc: Andy Whitcroft <apw@canonical.com> Cc: Christoph Lameter <cl@linux.com> Cc: Daniel Micay <danielmicay@gmail.com> Cc: David Rientjes <rientjes@google.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Dwaipayan Ray <dwaipayanray1@gmail.com> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Alexandre Bounine <alex.bou9@gmail.com> Cc: Gustavo A. R. Silva <gustavoars@kernel.org> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Jing Xiangfeng <jingxiangfeng@huawei.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: kernel test robot <lkp@intel.com> Cc: Matt Porter <mporter@kernel.crashing.org> Cc: Miguel Ojeda <ojeda@kernel.org> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Souptick Joarder <jrdr.linux@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
318 lines
13 KiB
C
318 lines
13 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __LINUX_COMPILER_ATTRIBUTES_H
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#define __LINUX_COMPILER_ATTRIBUTES_H
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/*
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* The attributes in this file are unconditionally defined and they directly
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* map to compiler attribute(s), unless one of the compilers does not support
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* the attribute. In that case, __has_attribute is used to check for support
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* and the reason is stated in its comment ("Optional: ...").
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*
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* Any other "attributes" (i.e. those that depend on a configuration option,
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* on a compiler, on an architecture, on plugins, on other attributes...)
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* should be defined elsewhere (e.g. compiler_types.h or compiler-*.h).
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* The intention is to keep this file as simple as possible, as well as
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* compiler- and version-agnostic (e.g. avoiding GCC_VERSION checks).
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*
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* This file is meant to be sorted (by actual attribute name,
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* not by #define identifier). Use the __attribute__((__name__)) syntax
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* (i.e. with underscores) to avoid future collisions with other macros.
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* Provide links to the documentation of each supported compiler, if it exists.
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*/
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/*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-alias-function-attribute
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*/
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#define __alias(symbol) __attribute__((__alias__(#symbol)))
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/*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-aligned-function-attribute
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-aligned-type-attribute
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-aligned-variable-attribute
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*/
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#define __aligned(x) __attribute__((__aligned__(x)))
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#define __aligned_largest __attribute__((__aligned__))
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/*
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* Note: do not use this directly. Instead, use __alloc_size() since it is conditionally
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* available and includes other attributes.
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*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-alloc_005fsize-function-attribute
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* clang: https://clang.llvm.org/docs/AttributeReference.html#alloc-size
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*/
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#define __alloc_size__(x, ...) __attribute__((__alloc_size__(x, ## __VA_ARGS__)))
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/*
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* Note: users of __always_inline currently do not write "inline" themselves,
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* which seems to be required by gcc to apply the attribute according
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* to its docs (and also "warning: always_inline function might not be
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* inlinable [-Wattributes]" is emitted).
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*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-always_005finline-function-attribute
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* clang: mentioned
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*/
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#define __always_inline inline __attribute__((__always_inline__))
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/*
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* The second argument is optional (default 0), so we use a variadic macro
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* to make the shorthand.
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*
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* Beware: Do not apply this to functions which may return
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* ERR_PTRs. Also, it is probably unwise to apply it to functions
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* returning extra information in the low bits (but in that case the
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* compiler should see some alignment anyway, when the return value is
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* massaged by 'flags = ptr & 3; ptr &= ~3;').
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*
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* Optional: not supported by icc
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*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-assume_005faligned-function-attribute
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* clang: https://clang.llvm.org/docs/AttributeReference.html#assume-aligned
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*/
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#if __has_attribute(__assume_aligned__)
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# define __assume_aligned(a, ...) __attribute__((__assume_aligned__(a, ## __VA_ARGS__)))
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#else
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# define __assume_aligned(a, ...)
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#endif
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/*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-cold-function-attribute
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Label-Attributes.html#index-cold-label-attribute
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*/
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#define __cold __attribute__((__cold__))
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/*
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* Note the long name.
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*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-const-function-attribute
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*/
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#define __attribute_const__ __attribute__((__const__))
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/*
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* Optional: only supported since gcc >= 9
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* Optional: not supported by clang
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* Optional: not supported by icc
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*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-copy-function-attribute
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*/
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#if __has_attribute(__copy__)
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# define __copy(symbol) __attribute__((__copy__(symbol)))
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#else
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# define __copy(symbol)
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#endif
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/*
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* Don't. Just don't. See commit 771c035372a0 ("deprecate the '__deprecated'
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* attribute warnings entirely and for good") for more information.
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*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-deprecated-function-attribute
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-deprecated-type-attribute
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-deprecated-variable-attribute
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Enumerator-Attributes.html#index-deprecated-enumerator-attribute
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* clang: https://clang.llvm.org/docs/AttributeReference.html#deprecated
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*/
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#define __deprecated
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/*
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* Optional: only supported since gcc >= 5.1
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* Optional: not supported by clang
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* Optional: not supported by icc
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*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-designated_005finit-type-attribute
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*/
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#if __has_attribute(__designated_init__)
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# define __designated_init __attribute__((__designated_init__))
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#else
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# define __designated_init
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#endif
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/*
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* Optional: only supported since clang >= 14.0
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*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-error-function-attribute
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*/
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#if __has_attribute(__error__)
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# define __compiletime_error(msg) __attribute__((__error__(msg)))
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#else
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# define __compiletime_error(msg)
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#endif
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/*
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* Optional: not supported by clang
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*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-externally_005fvisible-function-attribute
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*/
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#if __has_attribute(__externally_visible__)
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# define __visible __attribute__((__externally_visible__))
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#else
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# define __visible
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#endif
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/*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-format-function-attribute
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* clang: https://clang.llvm.org/docs/AttributeReference.html#format
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*/
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#define __printf(a, b) __attribute__((__format__(printf, a, b)))
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#define __scanf(a, b) __attribute__((__format__(scanf, a, b)))
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/*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-gnu_005finline-function-attribute
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* clang: https://clang.llvm.org/docs/AttributeReference.html#gnu-inline
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*/
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#define __gnu_inline __attribute__((__gnu_inline__))
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/*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-malloc-function-attribute
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* clang: https://clang.llvm.org/docs/AttributeReference.html#malloc
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*/
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#define __malloc __attribute__((__malloc__))
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/*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-mode-type-attribute
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-mode-variable-attribute
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*/
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#define __mode(x) __attribute__((__mode__(x)))
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/*
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* Optional: only supported since gcc >= 7
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*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/x86-Function-Attributes.html#index-no_005fcaller_005fsaved_005fregisters-function-attribute_002c-x86
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* clang: https://clang.llvm.org/docs/AttributeReference.html#no-caller-saved-registers
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*/
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#if __has_attribute(__no_caller_saved_registers__)
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# define __no_caller_saved_registers __attribute__((__no_caller_saved_registers__))
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#else
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# define __no_caller_saved_registers
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#endif
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/*
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* Optional: not supported by clang
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*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noclone-function-attribute
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*/
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#if __has_attribute(__noclone__)
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# define __noclone __attribute__((__noclone__))
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#else
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# define __noclone
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#endif
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/*
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* Add the pseudo keyword 'fallthrough' so case statement blocks
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* must end with any of these keywords:
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* break;
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* fallthrough;
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* continue;
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* goto <label>;
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* return [expression];
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*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Statement-Attributes.html#Statement-Attributes
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*/
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#if __has_attribute(__fallthrough__)
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# define fallthrough __attribute__((__fallthrough__))
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#else
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# define fallthrough do {} while (0) /* fallthrough */
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#endif
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/*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#Common-Function-Attributes
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* clang: https://clang.llvm.org/docs/AttributeReference.html#flatten
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*/
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# define __flatten __attribute__((flatten))
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/*
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* Note the missing underscores.
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*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noinline-function-attribute
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* clang: mentioned
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*/
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#define noinline __attribute__((__noinline__))
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/*
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* Optional: only supported since gcc >= 8
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* Optional: not supported by clang
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* Optional: not supported by icc
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*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-nonstring-variable-attribute
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*/
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#if __has_attribute(__nonstring__)
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# define __nonstring __attribute__((__nonstring__))
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#else
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# define __nonstring
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#endif
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/*
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* Optional: only supported since GCC >= 7.1, clang >= 13.0.
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*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-no_005fprofile_005finstrument_005ffunction-function-attribute
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* clang: https://clang.llvm.org/docs/AttributeReference.html#no-profile-instrument-function
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*/
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#if __has_attribute(__no_profile_instrument_function__)
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# define __no_profile __attribute__((__no_profile_instrument_function__))
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#else
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# define __no_profile
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#endif
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/*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noreturn-function-attribute
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* clang: https://clang.llvm.org/docs/AttributeReference.html#noreturn
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* clang: https://clang.llvm.org/docs/AttributeReference.html#id1
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*/
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#define __noreturn __attribute__((__noreturn__))
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/*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-packed-type-attribute
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* clang: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-packed-variable-attribute
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*/
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#define __packed __attribute__((__packed__))
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/*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-pure-function-attribute
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*/
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#define __pure __attribute__((__pure__))
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/*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-section-function-attribute
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-section-variable-attribute
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* clang: https://clang.llvm.org/docs/AttributeReference.html#section-declspec-allocate
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*/
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#define __section(section) __attribute__((__section__(section)))
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/*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-unused-function-attribute
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-unused-type-attribute
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-unused-variable-attribute
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Label-Attributes.html#index-unused-label-attribute
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* clang: https://clang.llvm.org/docs/AttributeReference.html#maybe-unused-unused
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*/
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#define __always_unused __attribute__((__unused__))
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#define __maybe_unused __attribute__((__unused__))
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/*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-used-function-attribute
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-used-variable-attribute
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*/
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#define __used __attribute__((__used__))
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/*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-warn_005funused_005fresult-function-attribute
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* clang: https://clang.llvm.org/docs/AttributeReference.html#nodiscard-warn-unused-result
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*/
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#define __must_check __attribute__((__warn_unused_result__))
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/*
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* Optional: only supported since clang >= 14.0
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*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-warning-function-attribute
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*/
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#if __has_attribute(__warning__)
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# define __compiletime_warning(msg) __attribute__((__warning__(msg)))
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#else
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# define __compiletime_warning(msg)
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#endif
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/*
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-weak-function-attribute
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* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-weak-variable-attribute
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*/
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#define __weak __attribute__((__weak__))
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#endif /* __LINUX_COMPILER_ATTRIBUTES_H */
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