uaccess_pt.c 12 KB

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  1. /*
  2. * User access functions based on page table walks for enhanced
  3. * system layout without hardware support.
  4. *
  5. * Copyright IBM Corp. 2006, 2012
  6. * Author(s): Gerald Schaefer (gerald.schaefer@de.ibm.com)
  7. */
  8. #include <linux/errno.h>
  9. #include <linux/hardirq.h>
  10. #include <linux/mm.h>
  11. #include <linux/hugetlb.h>
  12. #include <asm/uaccess.h>
  13. #include <asm/futex.h>
  14. #include "uaccess.h"
  15. #ifndef CONFIG_64BIT
  16. #define AHI "ahi"
  17. #define SLR "slr"
  18. #else
  19. #define AHI "aghi"
  20. #define SLR "slgr"
  21. #endif
  22. static size_t strnlen_kernel(size_t count, const char __user *src)
  23. {
  24. register unsigned long reg0 asm("0") = 0UL;
  25. unsigned long tmp1, tmp2;
  26. asm volatile(
  27. " la %2,0(%1)\n"
  28. " la %3,0(%0,%1)\n"
  29. " "SLR" %0,%0\n"
  30. "0: srst %3,%2\n"
  31. " jo 0b\n"
  32. " la %0,1(%3)\n" /* strnlen_kernel results includes \0 */
  33. " "SLR" %0,%1\n"
  34. "1:\n"
  35. EX_TABLE(0b,1b)
  36. : "+a" (count), "+a" (src), "=a" (tmp1), "=a" (tmp2)
  37. : "d" (reg0) : "cc", "memory");
  38. return count;
  39. }
  40. static size_t copy_in_kernel(size_t count, void __user *to,
  41. const void __user *from)
  42. {
  43. unsigned long tmp1;
  44. asm volatile(
  45. " "AHI" %0,-1\n"
  46. " jo 5f\n"
  47. " bras %3,3f\n"
  48. "0:"AHI" %0,257\n"
  49. "1: mvc 0(1,%1),0(%2)\n"
  50. " la %1,1(%1)\n"
  51. " la %2,1(%2)\n"
  52. " "AHI" %0,-1\n"
  53. " jnz 1b\n"
  54. " j 5f\n"
  55. "2: mvc 0(256,%1),0(%2)\n"
  56. " la %1,256(%1)\n"
  57. " la %2,256(%2)\n"
  58. "3:"AHI" %0,-256\n"
  59. " jnm 2b\n"
  60. "4: ex %0,1b-0b(%3)\n"
  61. "5:"SLR" %0,%0\n"
  62. "6:\n"
  63. EX_TABLE(1b,6b) EX_TABLE(2b,0b) EX_TABLE(4b,0b)
  64. : "+a" (count), "+a" (to), "+a" (from), "=a" (tmp1)
  65. : : "cc", "memory");
  66. return count;
  67. }
  68. /*
  69. * Returns kernel address for user virtual address. If the returned address is
  70. * >= -4095 (IS_ERR_VALUE(x) returns true), a fault has occured and the address
  71. * contains the (negative) exception code.
  72. */
  73. #ifdef CONFIG_64BIT
  74. static unsigned long follow_table(struct mm_struct *mm,
  75. unsigned long address, int write)
  76. {
  77. unsigned long *table = (unsigned long *)__pa(mm->pgd);
  78. switch (mm->context.asce_bits & _ASCE_TYPE_MASK) {
  79. case _ASCE_TYPE_REGION1:
  80. table = table + ((address >> 53) & 0x7ff);
  81. if (unlikely(*table & _REGION_ENTRY_INV))
  82. return -0x39UL;
  83. table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
  84. /* fallthrough */
  85. case _ASCE_TYPE_REGION2:
  86. table = table + ((address >> 42) & 0x7ff);
  87. if (unlikely(*table & _REGION_ENTRY_INV))
  88. return -0x3aUL;
  89. table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
  90. /* fallthrough */
  91. case _ASCE_TYPE_REGION3:
  92. table = table + ((address >> 31) & 0x7ff);
  93. if (unlikely(*table & _REGION_ENTRY_INV))
  94. return -0x3bUL;
  95. table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
  96. /* fallthrough */
  97. case _ASCE_TYPE_SEGMENT:
  98. table = table + ((address >> 20) & 0x7ff);
  99. if (unlikely(*table & _SEGMENT_ENTRY_INV))
  100. return -0x10UL;
  101. if (unlikely(*table & _SEGMENT_ENTRY_LARGE)) {
  102. if (write && (*table & _SEGMENT_ENTRY_RO))
  103. return -0x04UL;
  104. return (*table & _SEGMENT_ENTRY_ORIGIN_LARGE) +
  105. (address & ~_SEGMENT_ENTRY_ORIGIN_LARGE);
  106. }
  107. table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
  108. }
  109. table = table + ((address >> 12) & 0xff);
  110. if (unlikely(*table & _PAGE_INVALID))
  111. return -0x11UL;
  112. if (write && (*table & _PAGE_RO))
  113. return -0x04UL;
  114. return (*table & PAGE_MASK) + (address & ~PAGE_MASK);
  115. }
  116. #else /* CONFIG_64BIT */
  117. static unsigned long follow_table(struct mm_struct *mm,
  118. unsigned long address, int write)
  119. {
  120. unsigned long *table = (unsigned long *)__pa(mm->pgd);
  121. table = table + ((address >> 20) & 0x7ff);
  122. if (unlikely(*table & _SEGMENT_ENTRY_INV))
  123. return -0x10UL;
  124. table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
  125. table = table + ((address >> 12) & 0xff);
  126. if (unlikely(*table & _PAGE_INVALID))
  127. return -0x11UL;
  128. if (write && (*table & _PAGE_RO))
  129. return -0x04UL;
  130. return (*table & PAGE_MASK) + (address & ~PAGE_MASK);
  131. }
  132. #endif /* CONFIG_64BIT */
  133. static __always_inline size_t __user_copy_pt(unsigned long uaddr, void *kptr,
  134. size_t n, int write_user)
  135. {
  136. struct mm_struct *mm = current->mm;
  137. unsigned long offset, done, size, kaddr;
  138. void *from, *to;
  139. done = 0;
  140. retry:
  141. spin_lock(&mm->page_table_lock);
  142. do {
  143. kaddr = follow_table(mm, uaddr, write_user);
  144. if (IS_ERR_VALUE(kaddr))
  145. goto fault;
  146. offset = uaddr & ~PAGE_MASK;
  147. size = min(n - done, PAGE_SIZE - offset);
  148. if (write_user) {
  149. to = (void *) kaddr;
  150. from = kptr + done;
  151. } else {
  152. from = (void *) kaddr;
  153. to = kptr + done;
  154. }
  155. memcpy(to, from, size);
  156. done += size;
  157. uaddr += size;
  158. } while (done < n);
  159. spin_unlock(&mm->page_table_lock);
  160. return n - done;
  161. fault:
  162. spin_unlock(&mm->page_table_lock);
  163. if (__handle_fault(uaddr, -kaddr, write_user))
  164. return n - done;
  165. goto retry;
  166. }
  167. /*
  168. * Do DAT for user address by page table walk, return kernel address.
  169. * This function needs to be called with current->mm->page_table_lock held.
  170. */
  171. static __always_inline unsigned long __dat_user_addr(unsigned long uaddr,
  172. int write)
  173. {
  174. struct mm_struct *mm = current->mm;
  175. unsigned long kaddr;
  176. int rc;
  177. retry:
  178. kaddr = follow_table(mm, uaddr, write);
  179. if (IS_ERR_VALUE(kaddr))
  180. goto fault;
  181. return kaddr;
  182. fault:
  183. spin_unlock(&mm->page_table_lock);
  184. rc = __handle_fault(uaddr, -kaddr, write);
  185. spin_lock(&mm->page_table_lock);
  186. if (!rc)
  187. goto retry;
  188. return 0;
  189. }
  190. size_t copy_from_user_pt(size_t n, const void __user *from, void *to)
  191. {
  192. size_t rc;
  193. if (segment_eq(get_fs(), KERNEL_DS))
  194. return copy_in_kernel(n, (void __user *) to, from);
  195. rc = __user_copy_pt((unsigned long) from, to, n, 0);
  196. if (unlikely(rc))
  197. memset(to + n - rc, 0, rc);
  198. return rc;
  199. }
  200. size_t copy_to_user_pt(size_t n, void __user *to, const void *from)
  201. {
  202. if (segment_eq(get_fs(), KERNEL_DS))
  203. return copy_in_kernel(n, to, (void __user *) from);
  204. return __user_copy_pt((unsigned long) to, (void *) from, n, 1);
  205. }
  206. static size_t clear_user_pt(size_t n, void __user *to)
  207. {
  208. void *zpage = (void *) empty_zero_page;
  209. long done, size, ret;
  210. done = 0;
  211. do {
  212. if (n - done > PAGE_SIZE)
  213. size = PAGE_SIZE;
  214. else
  215. size = n - done;
  216. if (segment_eq(get_fs(), KERNEL_DS))
  217. ret = copy_in_kernel(n, to, (void __user *) zpage);
  218. else
  219. ret = __user_copy_pt((unsigned long) to, zpage, size, 1);
  220. done += size;
  221. to += size;
  222. if (ret)
  223. return ret + n - done;
  224. } while (done < n);
  225. return 0;
  226. }
  227. static size_t strnlen_user_pt(size_t count, const char __user *src)
  228. {
  229. unsigned long uaddr = (unsigned long) src;
  230. struct mm_struct *mm = current->mm;
  231. unsigned long offset, done, len, kaddr;
  232. size_t len_str;
  233. if (unlikely(!count))
  234. return 0;
  235. if (segment_eq(get_fs(), KERNEL_DS))
  236. return strnlen_kernel(count, src);
  237. done = 0;
  238. retry:
  239. spin_lock(&mm->page_table_lock);
  240. do {
  241. kaddr = follow_table(mm, uaddr, 0);
  242. if (IS_ERR_VALUE(kaddr))
  243. goto fault;
  244. offset = uaddr & ~PAGE_MASK;
  245. len = min(count - done, PAGE_SIZE - offset);
  246. len_str = strnlen((char *) kaddr, len);
  247. done += len_str;
  248. uaddr += len_str;
  249. } while ((len_str == len) && (done < count));
  250. spin_unlock(&mm->page_table_lock);
  251. return done + 1;
  252. fault:
  253. spin_unlock(&mm->page_table_lock);
  254. if (__handle_fault(uaddr, -kaddr, 0))
  255. return 0;
  256. goto retry;
  257. }
  258. static size_t strncpy_from_user_pt(size_t count, const char __user *src,
  259. char *dst)
  260. {
  261. size_t done, len, offset, len_str;
  262. if (unlikely(!count))
  263. return 0;
  264. done = 0;
  265. do {
  266. offset = (size_t)src & ~PAGE_MASK;
  267. len = min(count - done, PAGE_SIZE - offset);
  268. if (segment_eq(get_fs(), KERNEL_DS)) {
  269. if (copy_in_kernel(len, (void __user *) dst, src))
  270. return -EFAULT;
  271. } else {
  272. if (__user_copy_pt((unsigned long) src, dst, len, 0))
  273. return -EFAULT;
  274. }
  275. len_str = strnlen(dst, len);
  276. done += len_str;
  277. src += len_str;
  278. dst += len_str;
  279. } while ((len_str == len) && (done < count));
  280. return done;
  281. }
  282. static size_t copy_in_user_pt(size_t n, void __user *to,
  283. const void __user *from)
  284. {
  285. struct mm_struct *mm = current->mm;
  286. unsigned long offset_max, uaddr, done, size, error_code;
  287. unsigned long uaddr_from = (unsigned long) from;
  288. unsigned long uaddr_to = (unsigned long) to;
  289. unsigned long kaddr_to, kaddr_from;
  290. int write_user;
  291. if (segment_eq(get_fs(), KERNEL_DS))
  292. return copy_in_kernel(n, to, from);
  293. done = 0;
  294. retry:
  295. spin_lock(&mm->page_table_lock);
  296. do {
  297. write_user = 0;
  298. uaddr = uaddr_from;
  299. kaddr_from = follow_table(mm, uaddr_from, 0);
  300. error_code = kaddr_from;
  301. if (IS_ERR_VALUE(error_code))
  302. goto fault;
  303. write_user = 1;
  304. uaddr = uaddr_to;
  305. kaddr_to = follow_table(mm, uaddr_to, 1);
  306. error_code = (unsigned long) kaddr_to;
  307. if (IS_ERR_VALUE(error_code))
  308. goto fault;
  309. offset_max = max(uaddr_from & ~PAGE_MASK,
  310. uaddr_to & ~PAGE_MASK);
  311. size = min(n - done, PAGE_SIZE - offset_max);
  312. memcpy((void *) kaddr_to, (void *) kaddr_from, size);
  313. done += size;
  314. uaddr_from += size;
  315. uaddr_to += size;
  316. } while (done < n);
  317. spin_unlock(&mm->page_table_lock);
  318. return n - done;
  319. fault:
  320. spin_unlock(&mm->page_table_lock);
  321. if (__handle_fault(uaddr, -error_code, write_user))
  322. return n - done;
  323. goto retry;
  324. }
  325. #define __futex_atomic_op(insn, ret, oldval, newval, uaddr, oparg) \
  326. asm volatile("0: l %1,0(%6)\n" \
  327. "1: " insn \
  328. "2: cs %1,%2,0(%6)\n" \
  329. "3: jl 1b\n" \
  330. " lhi %0,0\n" \
  331. "4:\n" \
  332. EX_TABLE(0b,4b) EX_TABLE(2b,4b) EX_TABLE(3b,4b) \
  333. : "=d" (ret), "=&d" (oldval), "=&d" (newval), \
  334. "=m" (*uaddr) \
  335. : "0" (-EFAULT), "d" (oparg), "a" (uaddr), \
  336. "m" (*uaddr) : "cc" );
  337. static int __futex_atomic_op_pt(int op, u32 __user *uaddr, int oparg, int *old)
  338. {
  339. int oldval = 0, newval, ret;
  340. switch (op) {
  341. case FUTEX_OP_SET:
  342. __futex_atomic_op("lr %2,%5\n",
  343. ret, oldval, newval, uaddr, oparg);
  344. break;
  345. case FUTEX_OP_ADD:
  346. __futex_atomic_op("lr %2,%1\nar %2,%5\n",
  347. ret, oldval, newval, uaddr, oparg);
  348. break;
  349. case FUTEX_OP_OR:
  350. __futex_atomic_op("lr %2,%1\nor %2,%5\n",
  351. ret, oldval, newval, uaddr, oparg);
  352. break;
  353. case FUTEX_OP_ANDN:
  354. __futex_atomic_op("lr %2,%1\nnr %2,%5\n",
  355. ret, oldval, newval, uaddr, oparg);
  356. break;
  357. case FUTEX_OP_XOR:
  358. __futex_atomic_op("lr %2,%1\nxr %2,%5\n",
  359. ret, oldval, newval, uaddr, oparg);
  360. break;
  361. default:
  362. ret = -ENOSYS;
  363. }
  364. if (ret == 0)
  365. *old = oldval;
  366. return ret;
  367. }
  368. int futex_atomic_op_pt(int op, u32 __user *uaddr, int oparg, int *old)
  369. {
  370. int ret;
  371. if (segment_eq(get_fs(), KERNEL_DS))
  372. return __futex_atomic_op_pt(op, uaddr, oparg, old);
  373. spin_lock(&current->mm->page_table_lock);
  374. uaddr = (u32 __force __user *)
  375. __dat_user_addr((__force unsigned long) uaddr, 1);
  376. if (!uaddr) {
  377. spin_unlock(&current->mm->page_table_lock);
  378. return -EFAULT;
  379. }
  380. get_page(virt_to_page(uaddr));
  381. spin_unlock(&current->mm->page_table_lock);
  382. ret = __futex_atomic_op_pt(op, uaddr, oparg, old);
  383. put_page(virt_to_page(uaddr));
  384. return ret;
  385. }
  386. static int __futex_atomic_cmpxchg_pt(u32 *uval, u32 __user *uaddr,
  387. u32 oldval, u32 newval)
  388. {
  389. int ret;
  390. asm volatile("0: cs %1,%4,0(%5)\n"
  391. "1: la %0,0\n"
  392. "2:\n"
  393. EX_TABLE(0b,2b) EX_TABLE(1b,2b)
  394. : "=d" (ret), "+d" (oldval), "=m" (*uaddr)
  395. : "0" (-EFAULT), "d" (newval), "a" (uaddr), "m" (*uaddr)
  396. : "cc", "memory" );
  397. *uval = oldval;
  398. return ret;
  399. }
  400. int futex_atomic_cmpxchg_pt(u32 *uval, u32 __user *uaddr,
  401. u32 oldval, u32 newval)
  402. {
  403. int ret;
  404. if (segment_eq(get_fs(), KERNEL_DS))
  405. return __futex_atomic_cmpxchg_pt(uval, uaddr, oldval, newval);
  406. spin_lock(&current->mm->page_table_lock);
  407. uaddr = (u32 __force __user *)
  408. __dat_user_addr((__force unsigned long) uaddr, 1);
  409. if (!uaddr) {
  410. spin_unlock(&current->mm->page_table_lock);
  411. return -EFAULT;
  412. }
  413. get_page(virt_to_page(uaddr));
  414. spin_unlock(&current->mm->page_table_lock);
  415. ret = __futex_atomic_cmpxchg_pt(uval, uaddr, oldval, newval);
  416. put_page(virt_to_page(uaddr));
  417. return ret;
  418. }
  419. struct uaccess_ops uaccess_pt = {
  420. .copy_from_user = copy_from_user_pt,
  421. .copy_from_user_small = copy_from_user_pt,
  422. .copy_to_user = copy_to_user_pt,
  423. .copy_to_user_small = copy_to_user_pt,
  424. .copy_in_user = copy_in_user_pt,
  425. .clear_user = clear_user_pt,
  426. .strnlen_user = strnlen_user_pt,
  427. .strncpy_from_user = strncpy_from_user_pt,
  428. .futex_atomic_op = futex_atomic_op_pt,
  429. .futex_atomic_cmpxchg = futex_atomic_cmpxchg_pt,
  430. };