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