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