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