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