2 * arch/s390/lib/uaccess_pt.c
4 * User access functions based on page table walks for enhanced
5 * system layout without hardware support.
7 * Copyright IBM Corp. 2006
8 * Author(s): Gerald Schaefer (gerald.schaefer@de.ibm.com)
11 #include <linux/errno.h>
12 #include <linux/hardirq.h>
14 #include <asm/uaccess.h>
15 #include <asm/futex.h>
18 static inline pte_t *follow_table(struct mm_struct *mm, unsigned long addr)
24 pgd = pgd_offset(mm, addr);
25 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
26 return (pte_t *) 0x3a;
28 pud = pud_offset(pgd, addr);
29 if (pud_none(*pud) || unlikely(pud_bad(*pud)))
30 return (pte_t *) 0x3b;
32 pmd = pmd_offset(pud, addr);
33 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
34 return (pte_t *) 0x10;
36 return pte_offset_map(pmd, addr);
39 static __always_inline size_t __user_copy_pt(unsigned long uaddr, void *kptr,
40 size_t n, int write_user)
42 struct mm_struct *mm = current->mm;
43 unsigned long offset, pfn, done, size;
49 spin_lock(&mm->page_table_lock);
51 pte = follow_table(mm, uaddr);
52 if ((unsigned long) pte < 0x1000)
54 if (!pte_present(*pte)) {
57 } else if (write_user && !pte_write(*pte)) {
63 offset = uaddr & (PAGE_SIZE - 1);
64 size = min(n - done, PAGE_SIZE - offset);
66 to = (void *)((pfn << PAGE_SHIFT) + offset);
69 from = (void *)((pfn << PAGE_SHIFT) + offset);
72 memcpy(to, from, size);
76 spin_unlock(&mm->page_table_lock);
79 spin_unlock(&mm->page_table_lock);
80 if (__handle_fault(uaddr, (unsigned long) pte, write_user))
86 * Do DAT for user address by page table walk, return kernel address.
87 * This function needs to be called with current->mm->page_table_lock held.
89 static __always_inline unsigned long __dat_user_addr(unsigned long uaddr)
91 struct mm_struct *mm = current->mm;
97 pte = follow_table(mm, uaddr);
98 if ((unsigned long) pte < 0x1000)
100 if (!pte_present(*pte)) {
101 pte = (pte_t *) 0x11;
106 return (pfn << PAGE_SHIFT) + (uaddr & (PAGE_SIZE - 1));
108 spin_unlock(&mm->page_table_lock);
109 rc = __handle_fault(uaddr, (unsigned long) pte, 0);
110 spin_lock(&mm->page_table_lock);
116 size_t copy_from_user_pt(size_t n, const void __user *from, void *to)
120 if (segment_eq(get_fs(), KERNEL_DS)) {
121 memcpy(to, (void __kernel __force *) from, n);
124 rc = __user_copy_pt((unsigned long) from, to, n, 0);
126 memset(to + n - rc, 0, rc);
130 size_t copy_to_user_pt(size_t n, void __user *to, const void *from)
132 if (segment_eq(get_fs(), KERNEL_DS)) {
133 memcpy((void __kernel __force *) to, from, n);
136 return __user_copy_pt((unsigned long) to, (void *) from, n, 1);
139 static size_t clear_user_pt(size_t n, void __user *to)
141 long done, size, ret;
143 if (segment_eq(get_fs(), KERNEL_DS)) {
144 memset((void __kernel __force *) to, 0, n);
149 if (n - done > PAGE_SIZE)
153 ret = __user_copy_pt((unsigned long) to + done,
154 &empty_zero_page, size, 1);
157 return ret + n - done;
162 static size_t strnlen_user_pt(size_t count, const char __user *src)
165 unsigned long uaddr = (unsigned long) src;
166 struct mm_struct *mm = current->mm;
167 unsigned long offset, pfn, done, len;
171 if (segment_eq(get_fs(), KERNEL_DS))
172 return strnlen((const char __kernel __force *) src, count) + 1;
175 spin_lock(&mm->page_table_lock);
177 pte = follow_table(mm, uaddr);
178 if ((unsigned long) pte < 0x1000)
180 if (!pte_present(*pte)) {
181 pte = (pte_t *) 0x11;
186 offset = uaddr & (PAGE_SIZE-1);
187 addr = (char *)(pfn << PAGE_SHIFT) + offset;
188 len = min(count - done, PAGE_SIZE - offset);
189 len_str = strnlen(addr, len);
192 } while ((len_str == len) && (done < count));
193 spin_unlock(&mm->page_table_lock);
196 spin_unlock(&mm->page_table_lock);
197 if (__handle_fault(uaddr, (unsigned long) pte, 0))
202 static size_t strncpy_from_user_pt(size_t count, const char __user *src,
205 size_t n = strnlen_user_pt(count, src);
211 if (segment_eq(get_fs(), KERNEL_DS)) {
212 memcpy(dst, (const char __kernel __force *) src, n);
213 if (dst[n-1] == '\0')
218 if (__user_copy_pt((unsigned long) src, dst, n, 0))
220 if (dst[n-1] == '\0')
226 static size_t copy_in_user_pt(size_t n, void __user *to,
227 const void __user *from)
229 struct mm_struct *mm = current->mm;
230 unsigned long offset_from, offset_to, offset_max, pfn_from, pfn_to,
231 uaddr, done, size, error_code;
232 unsigned long uaddr_from = (unsigned long) from;
233 unsigned long uaddr_to = (unsigned long) to;
234 pte_t *pte_from, *pte_to;
237 if (segment_eq(get_fs(), KERNEL_DS)) {
238 memcpy((void __force *) to, (void __force *) from, n);
243 spin_lock(&mm->page_table_lock);
247 pte_from = follow_table(mm, uaddr_from);
248 error_code = (unsigned long) pte_from;
249 if (error_code < 0x1000)
251 if (!pte_present(*pte_from)) {
258 pte_to = follow_table(mm, uaddr_to);
259 error_code = (unsigned long) pte_to;
260 if (error_code < 0x1000)
262 if (!pte_present(*pte_to)) {
265 } else if (!pte_write(*pte_to)) {
270 pfn_from = pte_pfn(*pte_from);
271 pfn_to = pte_pfn(*pte_to);
272 offset_from = uaddr_from & (PAGE_SIZE-1);
273 offset_to = uaddr_from & (PAGE_SIZE-1);
274 offset_max = max(offset_from, offset_to);
275 size = min(n - done, PAGE_SIZE - offset_max);
277 memcpy((void *)(pfn_to << PAGE_SHIFT) + offset_to,
278 (void *)(pfn_from << PAGE_SHIFT) + offset_from, size);
283 spin_unlock(&mm->page_table_lock);
286 spin_unlock(&mm->page_table_lock);
287 if (__handle_fault(uaddr, error_code, write_user))
292 #define __futex_atomic_op(insn, ret, oldval, newval, uaddr, oparg) \
293 asm volatile("0: l %1,0(%6)\n" \
295 "2: cs %1,%2,0(%6)\n" \
299 EX_TABLE(0b,4b) EX_TABLE(2b,4b) EX_TABLE(3b,4b) \
300 : "=d" (ret), "=&d" (oldval), "=&d" (newval), \
302 : "0" (-EFAULT), "d" (oparg), "a" (uaddr), \
303 "m" (*uaddr) : "cc" );
305 static int __futex_atomic_op_pt(int op, int __user *uaddr, int oparg, int *old)
307 int oldval = 0, newval, ret;
311 __futex_atomic_op("lr %2,%5\n",
312 ret, oldval, newval, uaddr, oparg);
315 __futex_atomic_op("lr %2,%1\nar %2,%5\n",
316 ret, oldval, newval, uaddr, oparg);
319 __futex_atomic_op("lr %2,%1\nor %2,%5\n",
320 ret, oldval, newval, uaddr, oparg);
323 __futex_atomic_op("lr %2,%1\nnr %2,%5\n",
324 ret, oldval, newval, uaddr, oparg);
327 __futex_atomic_op("lr %2,%1\nxr %2,%5\n",
328 ret, oldval, newval, uaddr, oparg);
338 int futex_atomic_op_pt(int op, int __user *uaddr, int oparg, int *old)
342 if (segment_eq(get_fs(), KERNEL_DS))
343 return __futex_atomic_op_pt(op, uaddr, oparg, old);
344 spin_lock(¤t->mm->page_table_lock);
345 uaddr = (int __user *) __dat_user_addr((unsigned long) uaddr);
347 spin_unlock(¤t->mm->page_table_lock);
350 get_page(virt_to_page(uaddr));
351 spin_unlock(¤t->mm->page_table_lock);
352 ret = __futex_atomic_op_pt(op, uaddr, oparg, old);
353 put_page(virt_to_page(uaddr));
357 static int __futex_atomic_cmpxchg_pt(int __user *uaddr, int oldval, int newval)
361 asm volatile("0: cs %1,%4,0(%5)\n"
364 EX_TABLE(0b,2b) EX_TABLE(1b,2b)
365 : "=d" (ret), "+d" (oldval), "=m" (*uaddr)
366 : "0" (-EFAULT), "d" (newval), "a" (uaddr), "m" (*uaddr)
371 int futex_atomic_cmpxchg_pt(int __user *uaddr, int oldval, int newval)
375 if (segment_eq(get_fs(), KERNEL_DS))
376 return __futex_atomic_cmpxchg_pt(uaddr, oldval, newval);
377 spin_lock(¤t->mm->page_table_lock);
378 uaddr = (int __user *) __dat_user_addr((unsigned long) uaddr);
380 spin_unlock(¤t->mm->page_table_lock);
383 get_page(virt_to_page(uaddr));
384 spin_unlock(¤t->mm->page_table_lock);
385 ret = __futex_atomic_cmpxchg_pt(uaddr, oldval, newval);
386 put_page(virt_to_page(uaddr));
390 struct uaccess_ops uaccess_pt = {
391 .copy_from_user = copy_from_user_pt,
392 .copy_from_user_small = copy_from_user_pt,
393 .copy_to_user = copy_to_user_pt,
394 .copy_to_user_small = copy_to_user_pt,
395 .copy_in_user = copy_in_user_pt,
396 .clear_user = clear_user_pt,
397 .strnlen_user = strnlen_user_pt,
398 .strncpy_from_user = strncpy_from_user_pt,
399 .futex_atomic_op = futex_atomic_op_pt,
400 .futex_atomic_cmpxchg = futex_atomic_cmpxchg_pt,