1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_HIGHMEM_H
3 #define _LINUX_HIGHMEM_H
4 
5 #include <linux/fs.h>
6 #include <linux/kernel.h>
7 #include <linux/bug.h>
8 #include <linux/mm.h>
9 #include <linux/uaccess.h>
10 #include <linux/hardirq.h>
11 
12 #include <asm/cacheflush.h>
13 
14 #ifndef ARCH_HAS_FLUSH_ANON_PAGE
flush_anon_page(struct vm_area_struct * vma,struct page * page,unsigned long vmaddr)15 static inline void flush_anon_page(struct vm_area_struct *vma, struct page *page, unsigned long vmaddr)
16 {
17 }
18 #endif
19 
20 #ifndef ARCH_HAS_FLUSH_KERNEL_DCACHE_PAGE
flush_kernel_dcache_page(struct page * page)21 static inline void flush_kernel_dcache_page(struct page *page)
22 {
23 }
flush_kernel_vmap_range(void * vaddr,int size)24 static inline void flush_kernel_vmap_range(void *vaddr, int size)
25 {
26 }
invalidate_kernel_vmap_range(void * vaddr,int size)27 static inline void invalidate_kernel_vmap_range(void *vaddr, int size)
28 {
29 }
30 #endif
31 
32 #include <asm/kmap_types.h>
33 
34 #ifdef CONFIG_HIGHMEM
35 #include <asm/highmem.h>
36 
37 /* declarations for linux/mm/highmem.c */
38 unsigned int nr_free_highpages(void);
39 extern unsigned long totalhigh_pages;
40 
41 void kmap_flush_unused(void);
42 
43 struct page *kmap_to_page(void *addr);
44 
45 #else /* CONFIG_HIGHMEM */
46 
nr_free_highpages(void)47 static inline unsigned int nr_free_highpages(void) { return 0; }
48 
kmap_to_page(void * addr)49 static inline struct page *kmap_to_page(void *addr)
50 {
51 	return virt_to_page(addr);
52 }
53 
54 #define totalhigh_pages 0UL
55 
56 #ifndef ARCH_HAS_KMAP
kmap(struct page * page)57 static inline void *kmap(struct page *page)
58 {
59 	might_sleep();
60 	return page_address(page);
61 }
62 
kunmap(struct page * page)63 static inline void kunmap(struct page *page)
64 {
65 }
66 
kmap_atomic(struct page * page)67 static inline void *kmap_atomic(struct page *page)
68 {
69 	preempt_disable();
70 	pagefault_disable();
71 	return page_address(page);
72 }
73 #define kmap_atomic_prot(page, prot)	kmap_atomic(page)
74 
__kunmap_atomic(void * addr)75 static inline void __kunmap_atomic(void *addr)
76 {
77 	pagefault_enable();
78 	preempt_enable();
79 }
80 
81 #define kmap_atomic_pfn(pfn)	kmap_atomic(pfn_to_page(pfn))
82 
83 #define kmap_flush_unused()	do {} while(0)
84 #endif
85 
86 #endif /* CONFIG_HIGHMEM */
87 
88 #if defined(CONFIG_HIGHMEM) || defined(CONFIG_X86_32)
89 
90 DECLARE_PER_CPU(int, __kmap_atomic_idx);
91 
kmap_atomic_idx_push(void)92 static inline int kmap_atomic_idx_push(void)
93 {
94 	int idx = __this_cpu_inc_return(__kmap_atomic_idx) - 1;
95 
96 #ifdef CONFIG_DEBUG_HIGHMEM
97 	WARN_ON_ONCE(in_irq() && !irqs_disabled());
98 	BUG_ON(idx >= KM_TYPE_NR);
99 #endif
100 	return idx;
101 }
102 
kmap_atomic_idx(void)103 static inline int kmap_atomic_idx(void)
104 {
105 	return __this_cpu_read(__kmap_atomic_idx) - 1;
106 }
107 
kmap_atomic_idx_pop(void)108 static inline void kmap_atomic_idx_pop(void)
109 {
110 #ifdef CONFIG_DEBUG_HIGHMEM
111 	int idx = __this_cpu_dec_return(__kmap_atomic_idx);
112 
113 	BUG_ON(idx < 0);
114 #else
115 	__this_cpu_dec(__kmap_atomic_idx);
116 #endif
117 }
118 
119 #endif
120 
121 /*
122  * Prevent people trying to call kunmap_atomic() as if it were kunmap()
123  * kunmap_atomic() should get the return value of kmap_atomic, not the page.
124  */
125 #define kunmap_atomic(addr)                                     \
126 do {                                                            \
127 	BUILD_BUG_ON(__same_type((addr), struct page *));       \
128 	__kunmap_atomic(addr);                                  \
129 } while (0)
130 
131 
132 /* when CONFIG_HIGHMEM is not set these will be plain clear/copy_page */
133 #ifndef clear_user_highpage
clear_user_highpage(struct page * page,unsigned long vaddr)134 static inline void clear_user_highpage(struct page *page, unsigned long vaddr)
135 {
136 	void *addr = kmap_atomic(page);
137 	clear_user_page(addr, vaddr, page);
138 	kunmap_atomic(addr);
139 }
140 #endif
141 
142 #ifndef __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE
143 /**
144  * __alloc_zeroed_user_highpage - Allocate a zeroed HIGHMEM page for a VMA with caller-specified movable GFP flags
145  * @movableflags: The GFP flags related to the pages future ability to move like __GFP_MOVABLE
146  * @vma: The VMA the page is to be allocated for
147  * @vaddr: The virtual address the page will be inserted into
148  *
149  * This function will allocate a page for a VMA but the caller is expected
150  * to specify via movableflags whether the page will be movable in the
151  * future or not
152  *
153  * An architecture may override this function by defining
154  * __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE and providing their own
155  * implementation.
156  */
157 static inline struct page *
__alloc_zeroed_user_highpage(gfp_t movableflags,struct vm_area_struct * vma,unsigned long vaddr)158 __alloc_zeroed_user_highpage(gfp_t movableflags,
159 			struct vm_area_struct *vma,
160 			unsigned long vaddr)
161 {
162 	struct page *page = alloc_page_vma(GFP_HIGHUSER | movableflags,
163 			vma, vaddr);
164 
165 	if (page)
166 		clear_user_highpage(page, vaddr);
167 
168 	return page;
169 }
170 #endif
171 
172 /**
173  * alloc_zeroed_user_highpage_movable - Allocate a zeroed HIGHMEM page for a VMA that the caller knows can move
174  * @vma: The VMA the page is to be allocated for
175  * @vaddr: The virtual address the page will be inserted into
176  *
177  * This function will allocate a page for a VMA that the caller knows will
178  * be able to migrate in the future using move_pages() or reclaimed
179  */
180 static inline struct page *
alloc_zeroed_user_highpage_movable(struct vm_area_struct * vma,unsigned long vaddr)181 alloc_zeroed_user_highpage_movable(struct vm_area_struct *vma,
182 					unsigned long vaddr)
183 {
184 	return __alloc_zeroed_user_highpage(__GFP_MOVABLE, vma, vaddr);
185 }
186 
clear_highpage(struct page * page)187 static inline void clear_highpage(struct page *page)
188 {
189 	void *kaddr = kmap_atomic(page);
190 	clear_page(kaddr);
191 	kunmap_atomic(kaddr);
192 }
193 
zero_user_segments(struct page * page,unsigned start1,unsigned end1,unsigned start2,unsigned end2)194 static inline void zero_user_segments(struct page *page,
195 	unsigned start1, unsigned end1,
196 	unsigned start2, unsigned end2)
197 {
198 	void *kaddr = kmap_atomic(page);
199 
200 	BUG_ON(end1 > PAGE_SIZE || end2 > PAGE_SIZE);
201 
202 	if (end1 > start1)
203 		memset(kaddr + start1, 0, end1 - start1);
204 
205 	if (end2 > start2)
206 		memset(kaddr + start2, 0, end2 - start2);
207 
208 	kunmap_atomic(kaddr);
209 	flush_dcache_page(page);
210 }
211 
zero_user_segment(struct page * page,unsigned start,unsigned end)212 static inline void zero_user_segment(struct page *page,
213 	unsigned start, unsigned end)
214 {
215 	zero_user_segments(page, start, end, 0, 0);
216 }
217 
zero_user(struct page * page,unsigned start,unsigned size)218 static inline void zero_user(struct page *page,
219 	unsigned start, unsigned size)
220 {
221 	zero_user_segments(page, start, start + size, 0, 0);
222 }
223 
224 #ifndef __HAVE_ARCH_COPY_USER_HIGHPAGE
225 
copy_user_highpage(struct page * to,struct page * from,unsigned long vaddr,struct vm_area_struct * vma)226 static inline void copy_user_highpage(struct page *to, struct page *from,
227 	unsigned long vaddr, struct vm_area_struct *vma)
228 {
229 	char *vfrom, *vto;
230 
231 	vfrom = kmap_atomic(from);
232 	vto = kmap_atomic(to);
233 	copy_user_page(vto, vfrom, vaddr, to);
234 	kunmap_atomic(vto);
235 	kunmap_atomic(vfrom);
236 }
237 
238 #endif
239 
240 #ifndef __HAVE_ARCH_COPY_HIGHPAGE
241 
copy_highpage(struct page * to,struct page * from)242 static inline void copy_highpage(struct page *to, struct page *from)
243 {
244 	char *vfrom, *vto;
245 
246 	vfrom = kmap_atomic(from);
247 	vto = kmap_atomic(to);
248 	copy_page(vto, vfrom);
249 	kunmap_atomic(vto);
250 	kunmap_atomic(vfrom);
251 }
252 
253 #endif
254 
255 #endif /* _LINUX_HIGHMEM_H */
256