1 /* 2 * unaligned.c: Unaligned load/store trap handling with special 3 * cases for the kernel to do them more quickly. 4 * 5 * Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu) 6 * Copyright (C) 1996 Jakub Jelinek (jj@sunsite.mff.cuni.cz) 7 */ 8 9 10 #include <linux/kernel.h> 11 #include <linux/sched.h> 12 #include <linux/mm.h> 13 #include <linux/module.h> 14 #include <asm/ptrace.h> 15 #include <asm/processor.h> 16 #include <asm/system.h> 17 #include <asm/uaccess.h> 18 #include <linux/smp.h> 19 #include <linux/smp_lock.h> 20 21 /* #define DEBUG_MNA */ 22 23 enum direction { 24 load, /* ld, ldd, ldh, ldsh */ 25 store, /* st, std, sth, stsh */ 26 both, /* Swap, ldstub, etc. */ 27 fpload, 28 fpstore, 29 invalid, 30 }; 31 32 #ifdef DEBUG_MNA 33 static char *dirstrings[] = { 34 "load", "store", "both", "fpload", "fpstore", "invalid" 35 }; 36 #endif 37 38 static inline enum direction decode_direction(unsigned int insn) 39 { 40 unsigned long tmp = (insn >> 21) & 1; 41 42 if(!tmp) 43 return load; 44 else { 45 if(((insn>>19)&0x3f) == 15) 46 return both; 47 else 48 return store; 49 } 50 } 51 52 /* 8 = double-word, 4 = word, 2 = half-word */ 53 static inline int decode_access_size(unsigned int insn) 54 { 55 insn = (insn >> 19) & 3; 56 57 if(!insn) 58 return 4; 59 else if(insn == 3) 60 return 8; 61 else if(insn == 2) 62 return 2; 63 else { 64 printk("Impossible unaligned trap. insn=%08x\n", insn); 65 die_if_kernel("Byte sized unaligned access?!?!", current->thread.kregs); 66 return 4; /* just to keep gcc happy. */ 67 } 68 } 69 70 /* 0x400000 = signed, 0 = unsigned */ 71 static inline int decode_signedness(unsigned int insn) 72 { 73 return (insn & 0x400000); 74 } 75 76 static inline void maybe_flush_windows(unsigned int rs1, unsigned int rs2, 77 unsigned int rd) 78 { 79 if(rs2 >= 16 || rs1 >= 16 || rd >= 16) { 80 /* Wheee... */ 81 __asm__ __volatile__("save %sp, -0x40, %sp\n\t" 82 "save %sp, -0x40, %sp\n\t" 83 "save %sp, -0x40, %sp\n\t" 84 "save %sp, -0x40, %sp\n\t" 85 "save %sp, -0x40, %sp\n\t" 86 "save %sp, -0x40, %sp\n\t" 87 "save %sp, -0x40, %sp\n\t" 88 "restore; restore; restore; restore;\n\t" 89 "restore; restore; restore;\n\t"); 90 } 91 } 92 93 static inline int sign_extend_imm13(int imm) 94 { 95 return imm << 19 >> 19; 96 } 97 98 static inline unsigned long fetch_reg(unsigned int reg, struct pt_regs *regs) 99 { 100 struct reg_window32 *win; 101 102 if(reg < 16) 103 return (!reg ? 0 : regs->u_regs[reg]); 104 105 /* Ho hum, the slightly complicated case. */ 106 win = (struct reg_window32 *) regs->u_regs[UREG_FP]; 107 return win->locals[reg - 16]; /* yes, I know what this does... */ 108 } 109 110 static inline unsigned long safe_fetch_reg(unsigned int reg, struct pt_regs *regs) 111 { 112 struct reg_window32 __user *win; 113 unsigned long ret; 114 115 if (reg < 16) 116 return (!reg ? 0 : regs->u_regs[reg]); 117 118 /* Ho hum, the slightly complicated case. */ 119 win = (struct reg_window32 __user *) regs->u_regs[UREG_FP]; 120 121 if ((unsigned long)win & 3) 122 return -1; 123 124 if (get_user(ret, &win->locals[reg - 16])) 125 return -1; 126 127 return ret; 128 } 129 130 static inline unsigned long *fetch_reg_addr(unsigned int reg, struct pt_regs *regs) 131 { 132 struct reg_window32 *win; 133 134 if(reg < 16) 135 return ®s->u_regs[reg]; 136 win = (struct reg_window32 *) regs->u_regs[UREG_FP]; 137 return &win->locals[reg - 16]; 138 } 139 140 static unsigned long compute_effective_address(struct pt_regs *regs, 141 unsigned int insn) 142 { 143 unsigned int rs1 = (insn >> 14) & 0x1f; 144 unsigned int rs2 = insn & 0x1f; 145 unsigned int rd = (insn >> 25) & 0x1f; 146 147 if(insn & 0x2000) { 148 maybe_flush_windows(rs1, 0, rd); 149 return (fetch_reg(rs1, regs) + sign_extend_imm13(insn)); 150 } else { 151 maybe_flush_windows(rs1, rs2, rd); 152 return (fetch_reg(rs1, regs) + fetch_reg(rs2, regs)); 153 } 154 } 155 156 unsigned long safe_compute_effective_address(struct pt_regs *regs, 157 unsigned int insn) 158 { 159 unsigned int rs1 = (insn >> 14) & 0x1f; 160 unsigned int rs2 = insn & 0x1f; 161 unsigned int rd = (insn >> 25) & 0x1f; 162 163 if(insn & 0x2000) { 164 maybe_flush_windows(rs1, 0, rd); 165 return (safe_fetch_reg(rs1, regs) + sign_extend_imm13(insn)); 166 } else { 167 maybe_flush_windows(rs1, rs2, rd); 168 return (safe_fetch_reg(rs1, regs) + safe_fetch_reg(rs2, regs)); 169 } 170 } 171 172 /* This is just to make gcc think panic does return... */ 173 static void unaligned_panic(char *str) 174 { 175 panic(str); 176 } 177 178 /* una_asm.S */ 179 extern int do_int_load(unsigned long *dest_reg, int size, 180 unsigned long *saddr, int is_signed); 181 extern int __do_int_store(unsigned long *dst_addr, int size, 182 unsigned long *src_val); 183 184 static int do_int_store(int reg_num, int size, unsigned long *dst_addr, 185 struct pt_regs *regs) 186 { 187 unsigned long zero[2] = { 0, 0 }; 188 unsigned long *src_val; 189 190 if (reg_num) 191 src_val = fetch_reg_addr(reg_num, regs); 192 else { 193 src_val = &zero[0]; 194 if (size == 8) 195 zero[1] = fetch_reg(1, regs); 196 } 197 return __do_int_store(dst_addr, size, src_val); 198 } 199 200 extern void smp_capture(void); 201 extern void smp_release(void); 202 203 static inline void advance(struct pt_regs *regs) 204 { 205 regs->pc = regs->npc; 206 regs->npc += 4; 207 } 208 209 static inline int floating_point_load_or_store_p(unsigned int insn) 210 { 211 return (insn >> 24) & 1; 212 } 213 214 static inline int ok_for_kernel(unsigned int insn) 215 { 216 return !floating_point_load_or_store_p(insn); 217 } 218 219 static void kernel_mna_trap_fault(struct pt_regs *regs, unsigned int insn) 220 { 221 unsigned long g2 = regs->u_regs [UREG_G2]; 222 unsigned long fixup = search_extables_range(regs->pc, &g2); 223 224 if (!fixup) { 225 unsigned long address = compute_effective_address(regs, insn); 226 if(address < PAGE_SIZE) { 227 printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference in mna handler"); 228 } else 229 printk(KERN_ALERT "Unable to handle kernel paging request in mna handler"); 230 printk(KERN_ALERT " at virtual address %08lx\n",address); 231 printk(KERN_ALERT "current->{mm,active_mm}->context = %08lx\n", 232 (current->mm ? current->mm->context : 233 current->active_mm->context)); 234 printk(KERN_ALERT "current->{mm,active_mm}->pgd = %08lx\n", 235 (current->mm ? (unsigned long) current->mm->pgd : 236 (unsigned long) current->active_mm->pgd)); 237 die_if_kernel("Oops", regs); 238 /* Not reached */ 239 } 240 regs->pc = fixup; 241 regs->npc = regs->pc + 4; 242 regs->u_regs [UREG_G2] = g2; 243 } 244 245 asmlinkage void kernel_unaligned_trap(struct pt_regs *regs, unsigned int insn) 246 { 247 enum direction dir = decode_direction(insn); 248 int size = decode_access_size(insn); 249 250 if(!ok_for_kernel(insn) || dir == both) { 251 printk("Unsupported unaligned load/store trap for kernel at <%08lx>.\n", 252 regs->pc); 253 unaligned_panic("Wheee. Kernel does fpu/atomic unaligned load/store."); 254 } else { 255 unsigned long addr = compute_effective_address(regs, insn); 256 int err; 257 258 #ifdef DEBUG_MNA 259 printk("KMNA: pc=%08lx [dir=%s addr=%08lx size=%d] retpc[%08lx]\n", 260 regs->pc, dirstrings[dir], addr, size, regs->u_regs[UREG_RETPC]); 261 #endif 262 switch (dir) { 263 case load: 264 err = do_int_load(fetch_reg_addr(((insn>>25)&0x1f), 265 regs), 266 size, (unsigned long *) addr, 267 decode_signedness(insn)); 268 break; 269 270 case store: 271 err = do_int_store(((insn>>25)&0x1f), size, 272 (unsigned long *) addr, regs); 273 break; 274 default: 275 panic("Impossible kernel unaligned trap."); 276 /* Not reached... */ 277 } 278 if (err) 279 kernel_mna_trap_fault(regs, insn); 280 else 281 advance(regs); 282 } 283 } 284 285 static inline int ok_for_user(struct pt_regs *regs, unsigned int insn, 286 enum direction dir) 287 { 288 unsigned int reg; 289 int check = (dir == load) ? VERIFY_READ : VERIFY_WRITE; 290 int size = ((insn >> 19) & 3) == 3 ? 8 : 4; 291 292 if ((regs->pc | regs->npc) & 3) 293 return 0; 294 295 /* Must access_ok() in all the necessary places. */ 296 #define WINREG_ADDR(regnum) \ 297 ((void __user *)(((unsigned long *)regs->u_regs[UREG_FP])+(regnum))) 298 299 reg = (insn >> 25) & 0x1f; 300 if (reg >= 16) { 301 if (!access_ok(check, WINREG_ADDR(reg - 16), size)) 302 return -EFAULT; 303 } 304 reg = (insn >> 14) & 0x1f; 305 if (reg >= 16) { 306 if (!access_ok(check, WINREG_ADDR(reg - 16), size)) 307 return -EFAULT; 308 } 309 if (!(insn & 0x2000)) { 310 reg = (insn & 0x1f); 311 if (reg >= 16) { 312 if (!access_ok(check, WINREG_ADDR(reg - 16), size)) 313 return -EFAULT; 314 } 315 } 316 #undef WINREG_ADDR 317 return 0; 318 } 319 320 static void user_mna_trap_fault(struct pt_regs *regs, unsigned int insn) 321 { 322 siginfo_t info; 323 324 info.si_signo = SIGBUS; 325 info.si_errno = 0; 326 info.si_code = BUS_ADRALN; 327 info.si_addr = (void __user *)safe_compute_effective_address(regs, insn); 328 info.si_trapno = 0; 329 send_sig_info(SIGBUS, &info, current); 330 } 331 332 asmlinkage void user_unaligned_trap(struct pt_regs *regs, unsigned int insn) 333 { 334 enum direction dir; 335 336 lock_kernel(); 337 if(!(current->thread.flags & SPARC_FLAG_UNALIGNED) || 338 (((insn >> 30) & 3) != 3)) 339 goto kill_user; 340 dir = decode_direction(insn); 341 if(!ok_for_user(regs, insn, dir)) { 342 goto kill_user; 343 } else { 344 int err, size = decode_access_size(insn); 345 unsigned long addr; 346 347 if(floating_point_load_or_store_p(insn)) { 348 printk("User FPU load/store unaligned unsupported.\n"); 349 goto kill_user; 350 } 351 352 addr = compute_effective_address(regs, insn); 353 switch(dir) { 354 case load: 355 err = do_int_load(fetch_reg_addr(((insn>>25)&0x1f), 356 regs), 357 size, (unsigned long *) addr, 358 decode_signedness(insn)); 359 break; 360 361 case store: 362 err = do_int_store(((insn>>25)&0x1f), size, 363 (unsigned long *) addr, regs); 364 break; 365 366 case both: 367 /* 368 * This was supported in 2.4. However, we question 369 * the value of SWAP instruction across word boundaries. 370 */ 371 printk("Unaligned SWAP unsupported.\n"); 372 err = -EFAULT; 373 break; 374 375 default: 376 unaligned_panic("Impossible user unaligned trap."); 377 goto out; 378 } 379 if (err) 380 goto kill_user; 381 else 382 advance(regs); 383 goto out; 384 } 385 386 kill_user: 387 user_mna_trap_fault(regs, insn); 388 out: 389 unlock_kernel(); 390 } 391