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