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ff61f0791c
Move the x86 documentation under Documentation/arch/ as a way of cleaning up the top-level directory and making the structure of our docs more closely match the structure of the source directories it describes. All in-kernel references to the old paths have been updated. Acked-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: linux-arch@vger.kernel.org Cc: x86@kernel.org Cc: Borislav Petkov <bp@alien8.de> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/lkml/20230315211523.108836-1-corbet@lwn.net/ Signed-off-by: Jonathan Corbet <corbet@lwn.net>
75 lines
2 KiB
C
75 lines
2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __TOOLS_LINUX_ERR_H
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#define __TOOLS_LINUX_ERR_H
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#include <linux/compiler.h>
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#include <linux/types.h>
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#include <asm/errno.h>
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/*
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* Original kernel header comment:
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*
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* Kernel pointers have redundant information, so we can use a
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* scheme where we can return either an error code or a normal
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* pointer with the same return value.
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*
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* This should be a per-architecture thing, to allow different
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* error and pointer decisions.
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*
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* Userspace note:
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* The same principle works for userspace, because 'error' pointers
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* fall down to the unused hole far from user space, as described
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* in Documentation/arch/x86/x86_64/mm.rst for x86_64 arch:
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*
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* 0000000000000000 - 00007fffffffffff (=47 bits) user space, different per mm hole caused by [48:63] sign extension
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* ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole
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*
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* It should be the same case for other architectures, because
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* this code is used in generic kernel code.
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*/
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#define MAX_ERRNO 4095
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#define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO)
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static inline void * __must_check ERR_PTR(long error_)
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{
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return (void *) error_;
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}
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static inline long __must_check PTR_ERR(__force const void *ptr)
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{
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return (long) ptr;
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}
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static inline bool __must_check IS_ERR(__force const void *ptr)
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{
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return IS_ERR_VALUE((unsigned long)ptr);
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}
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static inline bool __must_check IS_ERR_OR_NULL(__force const void *ptr)
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{
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return unlikely(!ptr) || IS_ERR_VALUE((unsigned long)ptr);
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}
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static inline int __must_check PTR_ERR_OR_ZERO(__force const void *ptr)
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{
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if (IS_ERR(ptr))
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return PTR_ERR(ptr);
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else
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return 0;
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}
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/**
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* ERR_CAST - Explicitly cast an error-valued pointer to another pointer type
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* @ptr: The pointer to cast.
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*
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* Explicitly cast an error-valued pointer to another pointer type in such a
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* way as to make it clear that's what's going on.
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*/
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static inline void * __must_check ERR_CAST(__force const void *ptr)
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{
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/* cast away the const */
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return (void *) ptr;
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}
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#endif /* _LINUX_ERR_H */
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