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Linux/lib/ioremap.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  * Re-map IO memory to kernel address space so that we can access it.
  4  * This is needed for high PCI addresses that aren't mapped in the
  5  * 640k-1MB IO memory area on PC's
  6  *
  7  * (C) Copyright 1995 1996 Linus Torvalds
  8  */
  9 #include <linux/vmalloc.h>
 10 #include <linux/mm.h>
 11 #include <linux/sched.h>
 12 #include <linux/io.h>
 13 #include <linux/export.h>
 14 #include <asm/cacheflush.h>
 15 #include <asm/pgtable.h>
 16 
 17 #ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
 18 static int __read_mostly ioremap_p4d_capable;
 19 static int __read_mostly ioremap_pud_capable;
 20 static int __read_mostly ioremap_pmd_capable;
 21 static int __read_mostly ioremap_huge_disabled;
 22 
 23 static int __init set_nohugeiomap(char *str)
 24 {
 25         ioremap_huge_disabled = 1;
 26         return 0;
 27 }
 28 early_param("nohugeiomap", set_nohugeiomap);
 29 
 30 void __init ioremap_huge_init(void)
 31 {
 32         if (!ioremap_huge_disabled) {
 33                 if (arch_ioremap_p4d_supported())
 34                         ioremap_p4d_capable = 1;
 35                 if (arch_ioremap_pud_supported())
 36                         ioremap_pud_capable = 1;
 37                 if (arch_ioremap_pmd_supported())
 38                         ioremap_pmd_capable = 1;
 39         }
 40 }
 41 
 42 static inline int ioremap_p4d_enabled(void)
 43 {
 44         return ioremap_p4d_capable;
 45 }
 46 
 47 static inline int ioremap_pud_enabled(void)
 48 {
 49         return ioremap_pud_capable;
 50 }
 51 
 52 static inline int ioremap_pmd_enabled(void)
 53 {
 54         return ioremap_pmd_capable;
 55 }
 56 
 57 #else   /* !CONFIG_HAVE_ARCH_HUGE_VMAP */
 58 static inline int ioremap_p4d_enabled(void) { return 0; }
 59 static inline int ioremap_pud_enabled(void) { return 0; }
 60 static inline int ioremap_pmd_enabled(void) { return 0; }
 61 #endif  /* CONFIG_HAVE_ARCH_HUGE_VMAP */
 62 
 63 static int ioremap_pte_range(pmd_t *pmd, unsigned long addr,
 64                 unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
 65 {
 66         pte_t *pte;
 67         u64 pfn;
 68 
 69         pfn = phys_addr >> PAGE_SHIFT;
 70         pte = pte_alloc_kernel(pmd, addr);
 71         if (!pte)
 72                 return -ENOMEM;
 73         do {
 74                 BUG_ON(!pte_none(*pte));
 75                 set_pte_at(&init_mm, addr, pte, pfn_pte(pfn, prot));
 76                 pfn++;
 77         } while (pte++, addr += PAGE_SIZE, addr != end);
 78         return 0;
 79 }
 80 
 81 static int ioremap_try_huge_pmd(pmd_t *pmd, unsigned long addr,
 82                                 unsigned long end, phys_addr_t phys_addr,
 83                                 pgprot_t prot)
 84 {
 85         if (!ioremap_pmd_enabled())
 86                 return 0;
 87 
 88         if ((end - addr) != PMD_SIZE)
 89                 return 0;
 90 
 91         if (!IS_ALIGNED(addr, PMD_SIZE))
 92                 return 0;
 93 
 94         if (!IS_ALIGNED(phys_addr, PMD_SIZE))
 95                 return 0;
 96 
 97         if (pmd_present(*pmd) && !pmd_free_pte_page(pmd, addr))
 98                 return 0;
 99 
100         return pmd_set_huge(pmd, phys_addr, prot);
101 }
102 
103 static inline int ioremap_pmd_range(pud_t *pud, unsigned long addr,
104                 unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
105 {
106         pmd_t *pmd;
107         unsigned long next;
108 
109         pmd = pmd_alloc(&init_mm, pud, addr);
110         if (!pmd)
111                 return -ENOMEM;
112         do {
113                 next = pmd_addr_end(addr, end);
114 
115                 if (ioremap_try_huge_pmd(pmd, addr, next, phys_addr, prot))
116                         continue;
117 
118                 if (ioremap_pte_range(pmd, addr, next, phys_addr, prot))
119                         return -ENOMEM;
120         } while (pmd++, phys_addr += (next - addr), addr = next, addr != end);
121         return 0;
122 }
123 
124 static int ioremap_try_huge_pud(pud_t *pud, unsigned long addr,
125                                 unsigned long end, phys_addr_t phys_addr,
126                                 pgprot_t prot)
127 {
128         if (!ioremap_pud_enabled())
129                 return 0;
130 
131         if ((end - addr) != PUD_SIZE)
132                 return 0;
133 
134         if (!IS_ALIGNED(addr, PUD_SIZE))
135                 return 0;
136 
137         if (!IS_ALIGNED(phys_addr, PUD_SIZE))
138                 return 0;
139 
140         if (pud_present(*pud) && !pud_free_pmd_page(pud, addr))
141                 return 0;
142 
143         return pud_set_huge(pud, phys_addr, prot);
144 }
145 
146 static inline int ioremap_pud_range(p4d_t *p4d, unsigned long addr,
147                 unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
148 {
149         pud_t *pud;
150         unsigned long next;
151 
152         pud = pud_alloc(&init_mm, p4d, addr);
153         if (!pud)
154                 return -ENOMEM;
155         do {
156                 next = pud_addr_end(addr, end);
157 
158                 if (ioremap_try_huge_pud(pud, addr, next, phys_addr, prot))
159                         continue;
160 
161                 if (ioremap_pmd_range(pud, addr, next, phys_addr, prot))
162                         return -ENOMEM;
163         } while (pud++, phys_addr += (next - addr), addr = next, addr != end);
164         return 0;
165 }
166 
167 static int ioremap_try_huge_p4d(p4d_t *p4d, unsigned long addr,
168                                 unsigned long end, phys_addr_t phys_addr,
169                                 pgprot_t prot)
170 {
171         if (!ioremap_p4d_enabled())
172                 return 0;
173 
174         if ((end - addr) != P4D_SIZE)
175                 return 0;
176 
177         if (!IS_ALIGNED(addr, P4D_SIZE))
178                 return 0;
179 
180         if (!IS_ALIGNED(phys_addr, P4D_SIZE))
181                 return 0;
182 
183         if (p4d_present(*p4d) && !p4d_free_pud_page(p4d, addr))
184                 return 0;
185 
186         return p4d_set_huge(p4d, phys_addr, prot);
187 }
188 
189 static inline int ioremap_p4d_range(pgd_t *pgd, unsigned long addr,
190                 unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
191 {
192         p4d_t *p4d;
193         unsigned long next;
194 
195         p4d = p4d_alloc(&init_mm, pgd, addr);
196         if (!p4d)
197                 return -ENOMEM;
198         do {
199                 next = p4d_addr_end(addr, end);
200 
201                 if (ioremap_try_huge_p4d(p4d, addr, next, phys_addr, prot))
202                         continue;
203 
204                 if (ioremap_pud_range(p4d, addr, next, phys_addr, prot))
205                         return -ENOMEM;
206         } while (p4d++, phys_addr += (next - addr), addr = next, addr != end);
207         return 0;
208 }
209 
210 int ioremap_page_range(unsigned long addr,
211                        unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
212 {
213         pgd_t *pgd;
214         unsigned long start;
215         unsigned long next;
216         int err;
217 
218         might_sleep();
219         BUG_ON(addr >= end);
220 
221         start = addr;
222         pgd = pgd_offset_k(addr);
223         do {
224                 next = pgd_addr_end(addr, end);
225                 err = ioremap_p4d_range(pgd, addr, next, phys_addr, prot);
226                 if (err)
227                         break;
228         } while (pgd++, phys_addr += (next - addr), addr = next, addr != end);
229 
230         flush_cache_vmap(start, end);
231 
232         return err;
233 }
234 
235 #ifdef CONFIG_GENERIC_IOREMAP
236 void __iomem *ioremap_prot(phys_addr_t addr, size_t size, unsigned long prot)
237 {
238         unsigned long offset, vaddr;
239         phys_addr_t last_addr;
240         struct vm_struct *area;
241 
242         /* Disallow wrap-around or zero size */
243         last_addr = addr + size - 1;
244         if (!size || last_addr < addr)
245                 return NULL;
246 
247         /* Page-align mappings */
248         offset = addr & (~PAGE_MASK);
249         addr -= offset;
250         size = PAGE_ALIGN(size + offset);
251 
252         area = get_vm_area_caller(size, VM_IOREMAP,
253                         __builtin_return_address(0));
254         if (!area)
255                 return NULL;
256         vaddr = (unsigned long)area->addr;
257 
258         if (ioremap_page_range(vaddr, vaddr + size, addr, __pgprot(prot))) {
259                 free_vm_area(area);
260                 return NULL;
261         }
262 
263         return (void __iomem *)(vaddr + offset);
264 }
265 EXPORT_SYMBOL(ioremap_prot);
266 
267 void iounmap(volatile void __iomem *addr)
268 {
269         vunmap((void *)((unsigned long)addr & PAGE_MASK));
270 }
271 EXPORT_SYMBOL(iounmap);
272 #endif /* CONFIG_GENERIC_IOREMAP */
273 

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