2 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3 * Licensed under the GPL
7 #include <linux/highmem.h>
9 #include <linux/sched.h>
10 #include <asm/current.h>
12 #include <asm/pgtable.h>
13 #include "kern_util.h"
16 pte_t *virt_to_pte(struct mm_struct *mm, unsigned long addr)
25 pgd = pgd_offset(mm, addr);
26 if (!pgd_present(*pgd))
29 pud = pud_offset(pgd, addr);
30 if (!pud_present(*pud))
33 pmd = pmd_offset(pud, addr);
34 if (!pmd_present(*pmd))
37 return pte_offset_kernel(pmd, addr);
40 static pte_t *maybe_map(unsigned long virt, int is_write)
42 pte_t *pte = virt_to_pte(current->mm, virt);
45 if ((pte == NULL) || !pte_present(*pte) ||
46 (is_write && !pte_write(*pte))) {
47 err = handle_page_fault(virt, 0, is_write, 1, &dummy_code);
50 pte = virt_to_pte(current->mm, virt);
52 if (!pte_present(*pte))
58 static int do_op_one_page(unsigned long addr, int len, int is_write,
59 int (*op)(unsigned long addr, int len, void *arg), void *arg)
66 pte = maybe_map(addr, is_write);
70 page = pte_page(*pte);
71 addr = (unsigned long) kmap_atomic(page, KM_UML_USERCOPY) +
74 current->thread.fault_catcher = &buf;
76 faulted = UML_SETJMP(&buf);
78 n = (*op)(addr, len, arg);
82 current->thread.fault_catcher = NULL;
84 kunmap_atomic(page, KM_UML_USERCOPY);
89 static int buffer_op(unsigned long addr, int len, int is_write,
90 int (*op)(unsigned long, int, void *), void *arg)
94 size = min(PAGE_ALIGN(addr) - addr, (unsigned long) len);
97 n = do_op_one_page(addr, size, is_write, op, arg);
99 remain = (n < 0 ? remain : 0);
108 while (addr < ((addr + remain) & PAGE_MASK)) {
109 n = do_op_one_page(addr, PAGE_SIZE, is_write, op, arg);
111 remain = (n < 0 ? remain : 0);
121 n = do_op_one_page(addr, remain, is_write, op, arg);
123 remain = (n < 0 ? remain : 0);
132 static int copy_chunk_from_user(unsigned long from, int len, void *arg)
134 unsigned long *to_ptr = arg, to = *to_ptr;
136 memcpy((void *) to, (void *) from, len);
141 int copy_from_user(void *to, const void __user *from, int n)
143 if (segment_eq(get_fs(), KERNEL_DS)) {
144 memcpy(to, (__force void*)from, n);
148 return access_ok(VERIFY_READ, from, n) ?
149 buffer_op((unsigned long) from, n, 0, copy_chunk_from_user, &to):
153 static int copy_chunk_to_user(unsigned long to, int len, void *arg)
155 unsigned long *from_ptr = arg, from = *from_ptr;
157 memcpy((void *) to, (void *) from, len);
162 int copy_to_user(void __user *to, const void *from, int n)
164 if (segment_eq(get_fs(), KERNEL_DS)) {
165 memcpy((__force void *) to, from, n);
169 return access_ok(VERIFY_WRITE, to, n) ?
170 buffer_op((unsigned long) to, n, 1, copy_chunk_to_user, &from) :
174 static int strncpy_chunk_from_user(unsigned long from, int len, void *arg)
176 char **to_ptr = arg, *to = *to_ptr;
179 strncpy(to, (void *) from, len);
180 n = strnlen(to, len);
188 int strncpy_from_user(char *dst, const char __user *src, int count)
193 if (segment_eq(get_fs(), KERNEL_DS)) {
194 strncpy(dst, (__force void *) src, count);
195 return strnlen(dst, count);
198 if (!access_ok(VERIFY_READ, src, 1))
201 n = buffer_op((unsigned long) src, count, 0, strncpy_chunk_from_user,
205 return strnlen(dst, count);
208 static int clear_chunk(unsigned long addr, int len, void *unused)
210 memset((void *) addr, 0, len);
214 int __clear_user(void __user *mem, int len)
216 return buffer_op((unsigned long) mem, len, 1, clear_chunk, NULL);
219 int clear_user(void __user *mem, int len)
221 if (segment_eq(get_fs(), KERNEL_DS)) {
222 memset((__force void*)mem, 0, len);
226 return access_ok(VERIFY_WRITE, mem, len) ?
227 buffer_op((unsigned long) mem, len, 1, clear_chunk, NULL) : len;
230 static int strnlen_chunk(unsigned long str, int len, void *arg)
232 int *len_ptr = arg, n;
234 n = strnlen((void *) str, len);
242 int strnlen_user(const void __user *str, int len)
246 if (segment_eq(get_fs(), KERNEL_DS))
247 return strnlen((__force char*)str, len) + 1;
249 n = buffer_op((unsigned long) str, len, 0, strnlen_chunk, &count);