1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
7 #include <linux/highmem.h>
9 #include <linux/module.h>
10 #include <linux/sched.h>
11 #include <asm/current.h>
13 #include <kern_util.h>
16 pte_t *virt_to_pte(struct mm_struct *mm, unsigned long addr)
26 pgd = pgd_offset(mm, addr);
27 if (!pgd_present(*pgd))
30 p4d = p4d_offset(pgd, addr);
31 if (!p4d_present(*p4d))
34 pud = pud_offset(p4d, addr);
35 if (!pud_present(*pud))
38 pmd = pmd_offset(pud, addr);
39 if (!pmd_present(*pmd))
42 return pte_offset_kernel(pmd, addr);
45 static pte_t *maybe_map(unsigned long virt, int is_write)
47 pte_t *pte = virt_to_pte(current->mm, virt);
50 if ((pte == NULL) || !pte_present(*pte) ||
51 (is_write && !pte_write(*pte))) {
52 err = handle_page_fault(virt, 0, is_write, 1, &dummy_code);
55 pte = virt_to_pte(current->mm, virt);
57 if (!pte_present(*pte))
63 static int do_op_one_page(unsigned long addr, int len, int is_write,
64 int (*op)(unsigned long addr, int len, void *arg), void *arg)
70 pte = maybe_map(addr, is_write);
74 page = pte_page(*pte);
77 addr = (unsigned long) page_address(page) +
80 addr = (unsigned long) kmap_atomic(page) +
83 n = (*op)(addr, len, arg);
88 kunmap_atomic((void *)addr);
94 static long buffer_op(unsigned long addr, int len, int is_write,
95 int (*op)(unsigned long, int, void *), void *arg)
99 size = min(PAGE_ALIGN(addr) - addr, (unsigned long) len);
102 n = do_op_one_page(addr, size, is_write, op, arg);
104 remain = (n < 0 ? remain : 0);
113 while (addr < ((addr + remain) & PAGE_MASK)) {
114 n = do_op_one_page(addr, PAGE_SIZE, is_write, op, arg);
116 remain = (n < 0 ? remain : 0);
126 n = do_op_one_page(addr, remain, is_write, op, arg);
128 remain = (n < 0 ? remain : 0);
137 static int copy_chunk_from_user(unsigned long from, int len, void *arg)
139 unsigned long *to_ptr = arg, to = *to_ptr;
141 memcpy((void *) to, (void *) from, len);
146 unsigned long raw_copy_from_user(void *to, const void __user *from, unsigned long n)
148 if (uaccess_kernel()) {
149 memcpy(to, (__force void*)from, n);
153 return buffer_op((unsigned long) from, n, 0, copy_chunk_from_user, &to);
155 EXPORT_SYMBOL(raw_copy_from_user);
157 static int copy_chunk_to_user(unsigned long to, int len, void *arg)
159 unsigned long *from_ptr = arg, from = *from_ptr;
161 memcpy((void *) to, (void *) from, len);
166 unsigned long raw_copy_to_user(void __user *to, const void *from, unsigned long n)
168 if (uaccess_kernel()) {
169 memcpy((__force void *) to, from, n);
173 return buffer_op((unsigned long) to, n, 1, copy_chunk_to_user, &from);
175 EXPORT_SYMBOL(raw_copy_to_user);
177 static int strncpy_chunk_from_user(unsigned long from, int len, void *arg)
179 char **to_ptr = arg, *to = *to_ptr;
182 strncpy(to, (void *) from, len);
183 n = strnlen(to, len);
191 long __strncpy_from_user(char *dst, const char __user *src, long count)
196 if (uaccess_kernel()) {
197 strncpy(dst, (__force void *) src, count);
198 return strnlen(dst, count);
201 n = buffer_op((unsigned long) src, count, 0, strncpy_chunk_from_user,
205 return strnlen(dst, count);
207 EXPORT_SYMBOL(__strncpy_from_user);
209 static int clear_chunk(unsigned long addr, int len, void *unused)
211 memset((void *) addr, 0, len);
215 unsigned long __clear_user(void __user *mem, unsigned long len)
217 if (uaccess_kernel()) {
218 memset((__force void*)mem, 0, len);
222 return buffer_op((unsigned long) mem, len, 1, clear_chunk, NULL);
224 EXPORT_SYMBOL(__clear_user);
226 static int strnlen_chunk(unsigned long str, int len, void *arg)
228 int *len_ptr = arg, n;
230 n = strnlen((void *) str, len);
238 long __strnlen_user(const void __user *str, long len)
242 if (uaccess_kernel())
243 return strnlen((__force char*)str, len) + 1;
245 n = buffer_op((unsigned long) str, len, 0, strnlen_chunk, &count);
250 EXPORT_SYMBOL(__strnlen_user);