2 * User access functions based on page table walks for enhanced
3 * system layout without hardware support.
5 * Copyright IBM Corp. 2006, 2012
6 * Author(s): Gerald Schaefer (gerald.schaefer@de.ibm.com)
9 #include <linux/errno.h>
10 #include <linux/hardirq.h>
12 #include <linux/hugetlb.h>
13 #include <asm/uaccess.h>
14 #include <asm/futex.h>
25 static unsigned long strnlen_kernel(const char __user *src, unsigned long count)
27 register unsigned long reg0 asm("0") = 0UL;
28 unsigned long tmp1, tmp2;
36 " la %0,1(%3)\n" /* strnlen_kernel results includes \0 */
40 : "+a" (count), "+a" (src), "=a" (tmp1), "=a" (tmp2)
41 : "d" (reg0) : "cc", "memory");
45 static unsigned long copy_in_kernel(void __user *to, const void __user *from,
55 "1: mvc 0(1,%1),0(%2)\n"
61 "2: mvc 0(256,%1),0(%2)\n"
66 "4: ex %0,1b-0b(%3)\n"
69 EX_TABLE(1b,6b) EX_TABLE(2b,0b) EX_TABLE(4b,0b)
70 : "+a" (count), "+a" (to), "+a" (from), "=a" (tmp1)
76 * Returns kernel address for user virtual address. If the returned address is
77 * >= -4095 (IS_ERR_VALUE(x) returns true), a fault has occurred and the
78 * address contains the (negative) exception code.
82 static unsigned long follow_table(struct mm_struct *mm,
83 unsigned long address, int write)
85 unsigned long *table = (unsigned long *)__pa(mm->pgd);
87 if (unlikely(address > mm->context.asce_limit - 1))
89 switch (mm->context.asce_bits & _ASCE_TYPE_MASK) {
90 case _ASCE_TYPE_REGION1:
91 table = table + ((address >> 53) & 0x7ff);
92 if (unlikely(*table & _REGION_ENTRY_INVALID))
94 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
96 case _ASCE_TYPE_REGION2:
97 table = table + ((address >> 42) & 0x7ff);
98 if (unlikely(*table & _REGION_ENTRY_INVALID))
100 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
102 case _ASCE_TYPE_REGION3:
103 table = table + ((address >> 31) & 0x7ff);
104 if (unlikely(*table & _REGION_ENTRY_INVALID))
106 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
108 case _ASCE_TYPE_SEGMENT:
109 table = table + ((address >> 20) & 0x7ff);
110 if (unlikely(*table & _SEGMENT_ENTRY_INVALID))
112 if (unlikely(*table & _SEGMENT_ENTRY_LARGE)) {
113 if (write && (*table & _SEGMENT_ENTRY_PROTECT))
115 return (*table & _SEGMENT_ENTRY_ORIGIN_LARGE) +
116 (address & ~_SEGMENT_ENTRY_ORIGIN_LARGE);
118 table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
120 table = table + ((address >> 12) & 0xff);
121 if (unlikely(*table & _PAGE_INVALID))
123 if (write && (*table & _PAGE_PROTECT))
125 return (*table & PAGE_MASK) + (address & ~PAGE_MASK);
128 #else /* CONFIG_64BIT */
130 static unsigned long follow_table(struct mm_struct *mm,
131 unsigned long address, int write)
133 unsigned long *table = (unsigned long *)__pa(mm->pgd);
135 table = table + ((address >> 20) & 0x7ff);
136 if (unlikely(*table & _SEGMENT_ENTRY_INVALID))
138 table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
139 table = table + ((address >> 12) & 0xff);
140 if (unlikely(*table & _PAGE_INVALID))
142 if (write && (*table & _PAGE_PROTECT))
144 return (*table & PAGE_MASK) + (address & ~PAGE_MASK);
147 #endif /* CONFIG_64BIT */
149 static inline unsigned long __user_copy_pt(unsigned long uaddr, void *kptr,
150 unsigned long n, int write_user)
152 struct mm_struct *mm = current->mm;
153 unsigned long offset, done, size, kaddr;
160 spin_lock(&mm->page_table_lock);
162 kaddr = follow_table(mm, uaddr, write_user);
163 if (IS_ERR_VALUE(kaddr))
166 offset = uaddr & ~PAGE_MASK;
167 size = min(n - done, PAGE_SIZE - offset);
172 from = (void *) kaddr;
175 memcpy(to, from, size);
179 spin_unlock(&mm->page_table_lock);
182 spin_unlock(&mm->page_table_lock);
183 if (__handle_fault(uaddr, -kaddr, write_user))
189 * Do DAT for user address by page table walk, return kernel address.
190 * This function needs to be called with current->mm->page_table_lock held.
192 static inline unsigned long __dat_user_addr(unsigned long uaddr, int write)
194 struct mm_struct *mm = current->mm;
199 kaddr = follow_table(mm, uaddr, write);
200 if (IS_ERR_VALUE(kaddr))
205 spin_unlock(&mm->page_table_lock);
206 rc = __handle_fault(uaddr, -kaddr, write);
207 spin_lock(&mm->page_table_lock);
213 unsigned long copy_from_user_pt(void *to, const void __user *from, unsigned long n)
217 if (segment_eq(get_fs(), KERNEL_DS))
218 return copy_in_kernel((void __user *) to, from, n);
219 rc = __user_copy_pt((unsigned long) from, to, n, 0);
221 memset(to + n - rc, 0, rc);
225 unsigned long copy_to_user_pt(void __user *to, const void *from, unsigned long n)
227 if (segment_eq(get_fs(), KERNEL_DS))
228 return copy_in_kernel(to, (void __user *) from, n);
229 return __user_copy_pt((unsigned long) to, (void *) from, n, 1);
232 unsigned long clear_user_pt(void __user *to, unsigned long n)
234 void *zpage = (void *) empty_zero_page;
235 unsigned long done, size, ret;
239 if (n - done > PAGE_SIZE)
243 if (segment_eq(get_fs(), KERNEL_DS))
244 ret = copy_in_kernel(to, (void __user *) zpage, n);
246 ret = __user_copy_pt((unsigned long) to, zpage, size, 1);
250 return ret + n - done;
255 unsigned long strnlen_user_pt(const char __user *src, unsigned long count)
257 unsigned long uaddr = (unsigned long) src;
258 struct mm_struct *mm = current->mm;
259 unsigned long offset, done, len, kaddr;
260 unsigned long len_str;
262 if (unlikely(!count))
264 if (segment_eq(get_fs(), KERNEL_DS))
265 return strnlen_kernel(src, count);
270 spin_lock(&mm->page_table_lock);
272 kaddr = follow_table(mm, uaddr, 0);
273 if (IS_ERR_VALUE(kaddr))
276 offset = uaddr & ~PAGE_MASK;
277 len = min(count - done, PAGE_SIZE - offset);
278 len_str = strnlen((char *) kaddr, len);
281 } while ((len_str == len) && (done < count));
282 spin_unlock(&mm->page_table_lock);
285 spin_unlock(&mm->page_table_lock);
286 if (__handle_fault(uaddr, -kaddr, 0))
291 long strncpy_from_user_pt(char *dst, const char __user *src, long count)
293 unsigned long done, len, offset, len_str;
295 if (unlikely(count <= 0))
299 offset = (unsigned long)src & ~PAGE_MASK;
300 len = min(count - done, PAGE_SIZE - offset);
301 if (segment_eq(get_fs(), KERNEL_DS)) {
302 if (copy_in_kernel((void __user *) dst, src, len))
305 if (__user_copy_pt((unsigned long) src, dst, len, 0))
308 len_str = strnlen(dst, len);
312 } while ((len_str == len) && (done < count));
316 unsigned long copy_in_user_pt(void __user *to, const void __user *from,
319 struct mm_struct *mm = current->mm;
320 unsigned long offset_max, uaddr, done, size, error_code;
321 unsigned long uaddr_from = (unsigned long) from;
322 unsigned long uaddr_to = (unsigned long) to;
323 unsigned long kaddr_to, kaddr_from;
326 if (segment_eq(get_fs(), KERNEL_DS))
327 return copy_in_kernel(to, from, n);
332 spin_lock(&mm->page_table_lock);
336 kaddr_from = follow_table(mm, uaddr_from, 0);
337 error_code = kaddr_from;
338 if (IS_ERR_VALUE(error_code))
343 kaddr_to = follow_table(mm, uaddr_to, 1);
344 error_code = (unsigned long) kaddr_to;
345 if (IS_ERR_VALUE(error_code))
348 offset_max = max(uaddr_from & ~PAGE_MASK,
349 uaddr_to & ~PAGE_MASK);
350 size = min(n - done, PAGE_SIZE - offset_max);
352 memcpy((void *) kaddr_to, (void *) kaddr_from, size);
357 spin_unlock(&mm->page_table_lock);
360 spin_unlock(&mm->page_table_lock);
361 if (__handle_fault(uaddr, -error_code, write_user))
366 #define __futex_atomic_op(insn, ret, oldval, newval, uaddr, oparg) \
367 asm volatile("0: l %1,0(%6)\n" \
369 "2: cs %1,%2,0(%6)\n" \
373 EX_TABLE(0b,4b) EX_TABLE(2b,4b) EX_TABLE(3b,4b) \
374 : "=d" (ret), "=&d" (oldval), "=&d" (newval), \
376 : "0" (-EFAULT), "d" (oparg), "a" (uaddr), \
377 "m" (*uaddr) : "cc" );
379 static int __futex_atomic_op_pt(int op, u32 __user *uaddr, int oparg, int *old)
381 int oldval = 0, newval, ret;
385 __futex_atomic_op("lr %2,%5\n",
386 ret, oldval, newval, uaddr, oparg);
389 __futex_atomic_op("lr %2,%1\nar %2,%5\n",
390 ret, oldval, newval, uaddr, oparg);
393 __futex_atomic_op("lr %2,%1\nor %2,%5\n",
394 ret, oldval, newval, uaddr, oparg);
397 __futex_atomic_op("lr %2,%1\nnr %2,%5\n",
398 ret, oldval, newval, uaddr, oparg);
401 __futex_atomic_op("lr %2,%1\nxr %2,%5\n",
402 ret, oldval, newval, uaddr, oparg);
412 int __futex_atomic_op_inuser(int op, u32 __user *uaddr, int oparg, int *old)
416 if (segment_eq(get_fs(), KERNEL_DS))
417 return __futex_atomic_op_pt(op, uaddr, oparg, old);
418 if (unlikely(!current->mm))
420 spin_lock(¤t->mm->page_table_lock);
421 uaddr = (u32 __force __user *)
422 __dat_user_addr((__force unsigned long) uaddr, 1);
424 spin_unlock(¤t->mm->page_table_lock);
427 get_page(virt_to_page(uaddr));
428 spin_unlock(¤t->mm->page_table_lock);
429 ret = __futex_atomic_op_pt(op, uaddr, oparg, old);
430 put_page(virt_to_page(uaddr));
434 static int __futex_atomic_cmpxchg_pt(u32 *uval, u32 __user *uaddr,
435 u32 oldval, u32 newval)
439 asm volatile("0: cs %1,%4,0(%5)\n"
442 EX_TABLE(0b,2b) EX_TABLE(1b,2b)
443 : "=d" (ret), "+d" (oldval), "=m" (*uaddr)
444 : "0" (-EFAULT), "d" (newval), "a" (uaddr), "m" (*uaddr)
450 int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
451 u32 oldval, u32 newval)
455 if (segment_eq(get_fs(), KERNEL_DS))
456 return __futex_atomic_cmpxchg_pt(uval, uaddr, oldval, newval);
457 if (unlikely(!current->mm))
459 spin_lock(¤t->mm->page_table_lock);
460 uaddr = (u32 __force __user *)
461 __dat_user_addr((__force unsigned long) uaddr, 1);
463 spin_unlock(¤t->mm->page_table_lock);
466 get_page(virt_to_page(uaddr));
467 spin_unlock(¤t->mm->page_table_lock);
468 ret = __futex_atomic_cmpxchg_pt(uval, uaddr, oldval, newval);
469 put_page(virt_to_page(uaddr));