1/* 2 * arch/s390/lib/uaccess_pt.c 3 * 4 * User access functions based on page table walks for enhanced 5 * system layout without hardware support. 6 * 7 * Copyright IBM Corp. 2006 8 * Author(s): Gerald Schaefer (gerald.schaefer@de.ibm.com) 9 */ 10 11#include <linux/errno.h> 12#include <linux/hardirq.h> 13#include <linux/mm.h> 14#include <asm/uaccess.h> 15#include <asm/futex.h> 16#include "uaccess.h" 17 18static inline pte_t *follow_table(struct mm_struct *mm, unsigned long addr) 19{ 20 pgd_t *pgd; 21 pud_t *pud; 22 pmd_t *pmd; 23 24 pgd = pgd_offset(mm, addr); 25 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) 26 return (pte_t *) 0x3a; 27 28 pud = pud_offset(pgd, addr); 29 if (pud_none(*pud) || unlikely(pud_bad(*pud))) 30 return (pte_t *) 0x3b; 31 32 pmd = pmd_offset(pud, addr); 33 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) 34 return (pte_t *) 0x10; 35 36 return pte_offset_map(pmd, addr); 37} 38 39static __always_inline size_t __user_copy_pt(unsigned long uaddr, void *kptr, 40 size_t n, int write_user) 41{ 42 struct mm_struct *mm = current->mm; 43 unsigned long offset, pfn, done, size; 44 pte_t *pte; 45 void *from, *to; 46 47 done = 0; 48retry: 49 spin_lock(&mm->page_table_lock); 50 do { 51 pte = follow_table(mm, uaddr); 52 if ((unsigned long) pte < 0x1000) 53 goto fault; 54 if (!pte_present(*pte)) { 55 pte = (pte_t *) 0x11; 56 goto fault; 57 } else if (write_user && !pte_write(*pte)) { 58 pte = (pte_t *) 0x04; 59 goto fault; 60 } 61 62 pfn = pte_pfn(*pte); 63 offset = uaddr & (PAGE_SIZE - 1); 64 size = min(n - done, PAGE_SIZE - offset); 65 if (write_user) { 66 to = (void *)((pfn << PAGE_SHIFT) + offset); 67 from = kptr + done; 68 } else { 69 from = (void *)((pfn << PAGE_SHIFT) + offset); 70 to = kptr + done; 71 } 72 memcpy(to, from, size); 73 done += size; 74 uaddr += size; 75 } while (done < n); 76 spin_unlock(&mm->page_table_lock); 77 return n - done; 78fault: 79 spin_unlock(&mm->page_table_lock); 80 if (__handle_fault(uaddr, (unsigned long) pte, write_user)) 81 return n - done; 82 goto retry; 83} 84 85/* 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. 88 */ 89static __always_inline unsigned long __dat_user_addr(unsigned long uaddr) 90{ 91 struct mm_struct *mm = current->mm; 92 unsigned long pfn; 93 pte_t *pte; 94 int rc; 95 96retry: 97 pte = follow_table(mm, uaddr); 98 if ((unsigned long) pte < 0x1000) 99 goto fault; 100 if (!pte_present(*pte)) { 101 pte = (pte_t *) 0x11; 102 goto fault; 103 } 104 105 pfn = pte_pfn(*pte); 106 return (pfn << PAGE_SHIFT) + (uaddr & (PAGE_SIZE - 1)); 107fault: 108 spin_unlock(&mm->page_table_lock); 109 rc = __handle_fault(uaddr, (unsigned long) pte, 0); 110 spin_lock(&mm->page_table_lock); 111 if (!rc) 112 goto retry; 113 return 0; 114} 115 116size_t copy_from_user_pt(size_t n, const void __user *from, void *to) 117{ 118 size_t rc; 119 120 if (segment_eq(get_fs(), KERNEL_DS)) { 121 memcpy(to, (void __kernel __force *) from, n); 122 return 0; 123 } 124 rc = __user_copy_pt((unsigned long) from, to, n, 0); 125 if (unlikely(rc)) 126 memset(to + n - rc, 0, rc); 127 return rc; 128} 129 130size_t copy_to_user_pt(size_t n, void __user *to, const void *from) 131{ 132 if (segment_eq(get_fs(), KERNEL_DS)) { 133 memcpy((void __kernel __force *) to, from, n); 134 return 0; 135 } 136 return __user_copy_pt((unsigned long) to, (void *) from, n, 1); 137} 138 139static size_t clear_user_pt(size_t n, void __user *to) 140{ 141 long done, size, ret; 142 143 if (segment_eq(get_fs(), KERNEL_DS)) { 144 memset((void __kernel __force *) to, 0, n); 145 return 0; 146 } 147 done = 0; 148 do { 149 if (n - done > PAGE_SIZE) 150 size = PAGE_SIZE; 151 else 152 size = n - done; 153 ret = __user_copy_pt((unsigned long) to + done, 154 &empty_zero_page, size, 1); 155 done += size; 156 if (ret) 157 return ret + n - done; 158 } while (done < n); 159 return 0; 160} 161 162static size_t strnlen_user_pt(size_t count, const char __user *src) 163{ 164 char *addr; 165 unsigned long uaddr = (unsigned long) src; 166 struct mm_struct *mm = current->mm; 167 unsigned long offset, pfn, done, len; 168 pte_t *pte; 169 size_t len_str; 170 171 if (segment_eq(get_fs(), KERNEL_DS)) 172 return strnlen((const char __kernel __force *) src, count) + 1; 173 done = 0; 174retry: 175 spin_lock(&mm->page_table_lock); 176 do { 177 pte = follow_table(mm, uaddr); 178 if ((unsigned long) pte < 0x1000) 179 goto fault; 180 if (!pte_present(*pte)) { 181 pte = (pte_t *) 0x11; 182 goto fault; 183 } 184 185 pfn = pte_pfn(*pte); 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); 190 done += len_str; 191 uaddr += len_str; 192 } while ((len_str == len) && (done < count)); 193 spin_unlock(&mm->page_table_lock); 194 return done + 1; 195fault: 196 spin_unlock(&mm->page_table_lock); 197 if (__handle_fault(uaddr, (unsigned long) pte, 0)) 198 return 0; 199 goto retry; 200} 201 202static size_t strncpy_from_user_pt(size_t count, const char __user *src, 203 char *dst) 204{ 205 size_t n = strnlen_user_pt(count, src); 206 207 if (!n) 208 return -EFAULT; 209 if (n > count) 210 n = count; 211 if (segment_eq(get_fs(), KERNEL_DS)) { 212 memcpy(dst, (const char __kernel __force *) src, n); 213 if (dst[n-1] == '\0') 214 return n-1; 215 else 216 return n; 217 } 218 if (__user_copy_pt((unsigned long) src, dst, n, 0)) 219 return -EFAULT; 220 if (dst[n-1] == '\0') 221 return n-1; 222 else 223 return n; 224} 225 226static size_t copy_in_user_pt(size_t n, void __user *to, 227 const void __user *from) 228{ 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; 235 int write_user; 236 237 if (segment_eq(get_fs(), KERNEL_DS)) { 238 memcpy((void __force *) to, (void __force *) from, n); 239 return 0; 240 } 241 done = 0; 242retry: 243 spin_lock(&mm->page_table_lock); 244 do { 245 write_user = 0; 246 uaddr = uaddr_from; 247 pte_from = follow_table(mm, uaddr_from); 248 error_code = (unsigned long) pte_from; 249 if (error_code < 0x1000) 250 goto fault; 251 if (!pte_present(*pte_from)) { 252 error_code = 0x11; 253 goto fault; 254 } 255 256 write_user = 1; 257 uaddr = uaddr_to; 258 pte_to = follow_table(mm, uaddr_to); 259 error_code = (unsigned long) pte_to; 260 if (error_code < 0x1000) 261 goto fault; 262 if (!pte_present(*pte_to)) { 263 error_code = 0x11; 264 goto fault; 265 } else if (!pte_write(*pte_to)) { 266 error_code = 0x04; 267 goto fault; 268 } 269 270 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); 276 277 memcpy((void *)(pfn_to << PAGE_SHIFT) + offset_to, 278 (void *)(pfn_from << PAGE_SHIFT) + offset_from, size); 279 done += size; 280 uaddr_from += size; 281 uaddr_to += size; 282 } while (done < n); 283 spin_unlock(&mm->page_table_lock); 284 return n - done; 285fault: 286 spin_unlock(&mm->page_table_lock); 287 if (__handle_fault(uaddr, error_code, write_user)) 288 return n - done; 289 goto retry; 290} 291 292#define __futex_atomic_op(insn, ret, oldval, newval, uaddr, oparg) \ 293 asm volatile("0: l %1,0(%6)\n" \ 294 "1: " insn \ 295 "2: cs %1,%2,0(%6)\n" \ 296 "3: jl 1b\n" \ 297 " lhi %0,0\n" \ 298 "4:\n" \ 299 EX_TABLE(0b,4b) EX_TABLE(2b,4b) EX_TABLE(3b,4b) \ 300 : "=d" (ret), "=&d" (oldval), "=&d" (newval), \ 301 "=m" (*uaddr) \ 302 : "0" (-EFAULT), "d" (oparg), "a" (uaddr), \ 303 "m" (*uaddr) : "cc" ); 304 305static int __futex_atomic_op_pt(int op, int __user *uaddr, int oparg, int *old) 306{ 307 int oldval = 0, newval, ret; 308 309 switch (op) { 310 case FUTEX_OP_SET: 311 __futex_atomic_op("lr %2,%5\n", 312 ret, oldval, newval, uaddr, oparg); 313 break; 314 case FUTEX_OP_ADD: 315 __futex_atomic_op("lr %2,%1\nar %2,%5\n", 316 ret, oldval, newval, uaddr, oparg); 317 break; 318 case FUTEX_OP_OR: 319 __futex_atomic_op("lr %2,%1\nor %2,%5\n", 320 ret, oldval, newval, uaddr, oparg); 321 break; 322 case FUTEX_OP_ANDN: 323 __futex_atomic_op("lr %2,%1\nnr %2,%5\n", 324 ret, oldval, newval, uaddr, oparg); 325 break; 326 case FUTEX_OP_XOR: 327 __futex_atomic_op("lr %2,%1\nxr %2,%5\n", 328 ret, oldval, newval, uaddr, oparg); 329 break; 330 default: 331 ret = -ENOSYS; 332 } 333 if (ret == 0) 334 *old = oldval; 335 return ret; 336} 337 338int futex_atomic_op_pt(int op, int __user *uaddr, int oparg, int *old) 339{ 340 int ret; 341 342 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); 346 if (!uaddr) { 347 spin_unlock(¤t->mm->page_table_lock); 348 return -EFAULT; 349 } 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)); 354 return ret; 355} 356 357static int __futex_atomic_cmpxchg_pt(int __user *uaddr, int oldval, int newval) 358{ 359 int ret; 360 361 asm volatile("0: cs %1,%4,0(%5)\n" 362 "1: lr %0,%1\n" 363 "2:\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) 367 : "cc", "memory" ); 368 return ret; 369} 370 371int futex_atomic_cmpxchg_pt(int __user *uaddr, int oldval, int newval) 372{ 373 int ret; 374 375 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); 379 if (!uaddr) { 380 spin_unlock(¤t->mm->page_table_lock); 381 return -EFAULT; 382 } 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)); 387 return ret; 388} 389 390struct 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, 401}; 402