i915_ptr_util.h

 1/* SPDX-License-Identifier: MIT */
 2/* Copyright © 2025 Intel Corporation */
 3
 4#ifndef __I915_PTR_UTIL_H__
 5#define __I915_PTR_UTIL_H__
 6
 7#include <linux/types.h>
 8
 9#define ptr_mask_bits(ptr, n) ({					\
10	unsigned long __v = (unsigned long)(ptr);			\
11	(typeof(ptr))(__v & -BIT(n));					\
12})
13
14#define ptr_unmask_bits(ptr, n) ((unsigned long)(ptr) & (BIT(n) - 1))
15
16#define ptr_unpack_bits(ptr, bits, n) ({				\
17	unsigned long __v = (unsigned long)(ptr);			\
18	*(bits) = __v & (BIT(n) - 1);					\
19	(typeof(ptr))(__v & -BIT(n));					\
20})
21
22#define ptr_pack_bits(ptr, bits, n) ({					\
23	unsigned long __bits = (bits);					\
24	GEM_BUG_ON(__bits & -BIT(n));					\
25	((typeof(ptr))((unsigned long)(ptr) | __bits));			\
26})
27
28#define ptr_dec(ptr) ({							\
29	unsigned long __v = (unsigned long)(ptr);			\
30	(typeof(ptr))(__v - 1);						\
31})
32
33#define ptr_inc(ptr) ({							\
34	unsigned long __v = (unsigned long)(ptr);			\
35	(typeof(ptr))(__v + 1);						\
36})
37
38#define page_mask_bits(ptr) ptr_mask_bits(ptr, PAGE_SHIFT)
39#define page_unmask_bits(ptr) ptr_unmask_bits(ptr, PAGE_SHIFT)
40#define page_pack_bits(ptr, bits) ptr_pack_bits(ptr, bits, PAGE_SHIFT)
41#define page_unpack_bits(ptr, bits) ptr_unpack_bits(ptr, bits, PAGE_SHIFT)
42
43static __always_inline ptrdiff_t ptrdiff(const void *a, const void *b)
44{
45	return a - b;
46}
47
48#define u64_to_ptr(T, x) ({						\
49	typecheck(u64, x);						\
50	(T *)(uintptr_t)(x);						\
51})
52
53/*
54 * container_of_user: Extract the superclass from a pointer to a member.
55 *
56 * Exactly like container_of() with the exception that it plays nicely
57 * with sparse for __user @ptr.
58 */
59#define container_of_user(ptr, type, member) ({				\
60	void __user *__mptr = (void __user *)(ptr);			\
61	BUILD_BUG_ON_MSG(!__same_type(*(ptr), typeof_member(type, member)) && \
62			 !__same_type(*(ptr), void),			\
63			 "pointer type mismatch in container_of()");	\
64	((type __user *)(__mptr - offsetof(type, member))); })
65
66#endif /* __I915_PTR_UTIL_H__ */