arch/sparc/kernel/unaligned_32.c

   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
  21 /* #define DEBUG_MNA */
  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 #ifdef DEBUG_MNA
  33 static char *dirstrings[] = {
  34   "load", "store", "both", "fpload", "fpstore", "invalid"
  35 };
  36 #endif
  37
  38 static inline enum direction decode_direction(unsigned int insn)
  39 {
  40         unsigned long tmp = (insn >> 21) & 1;
  41
  42         if(!tmp)
  43                 return load;
  44         else {
  45                 if(((insn>>19)&0x3f) == 15)
  46                         return both;
  47                 else
  48                         return store;
  49         }
  50 }
  51
  52 /* 8 = double-word, 4 = word, 2 = half-word */
  53 static inline int decode_access_size(unsigned int insn)
  54 {
  55         insn = (insn >> 19) & 3;
  56
  57         if(!insn)
  58                 return 4;
  59         else if(insn == 3)
  60                 return 8;
  61         else if(insn == 2)
  62                 return 2;
  63         else {
  64                 printk("Impossible unaligned trap. insn=%08x\n", insn);
  65                 die_if_kernel("Byte sized unaligned access?!?!", current->thread.kregs);
  66                 return 4; /* just to keep gcc happy. */
  67         }
  68 }
  69
  70 /* 0x400000 = signed, 0 = unsigned */
  71 static inline int decode_signedness(unsigned int insn)
  72 {
  73         return (insn & 0x400000);
  74 }
  75
  76 static inline void maybe_flush_windows(unsigned int rs1, unsigned int rs2,
  77                                        unsigned int rd)
  78 {
  79         if(rs2 >= 16 || rs1 >= 16 || rd >= 16) {
  80                 /* Wheee... */
  81                 __asm__ __volatile__("save %sp, -0x40, %sp\n\t"
  82                                      "save %sp, -0x40, %sp\n\t"
  83                                      "save %sp, -0x40, %sp\n\t"
  84                                      "save %sp, -0x40, %sp\n\t"
  85                                      "save %sp, -0x40, %sp\n\t"
  86                                      "save %sp, -0x40, %sp\n\t"
  87                                      "save %sp, -0x40, %sp\n\t"
  88                                      "restore; restore; restore; restore;\n\t"
  89                                      "restore; restore; restore;\n\t");
  90         }
  91 }
  92
  93 static inline int sign_extend_imm13(int imm)
  94 {
  95         return imm << 19 >> 19;
  96 }
  97
  98 static inline unsigned long fetch_reg(unsigned int reg, struct pt_regs *regs)
  99 {
 100         struct reg_window32 *win;
 101
 102         if(reg < 16)
 103                 return (!reg ? 0 : regs->u_regs[reg]);
 104
 105         /* Ho hum, the slightly complicated case. */
 106         win = (struct reg_window32 *) regs->u_regs[UREG_FP];
 107         return win->locals[reg - 16]; /* yes, I know what this does... */
 108 }
 109
 110 static inline unsigned long safe_fetch_reg(unsigned int reg, struct pt_regs *regs)
 111 {
 112         struct reg_window32 __user *win;
 113         unsigned long ret;
 114
 115         if (reg < 16)
 116                 return (!reg ? 0 : regs->u_regs[reg]);
 117
 118         /* Ho hum, the slightly complicated case. */
 119         win = (struct reg_window32 __user *) regs->u_regs[UREG_FP];
 120
 121         if ((unsigned long)win & 3)
 122                 return -1;
 123
 124         if (get_user(ret, &win->locals[reg - 16]))
 125                 return -1;
 126
 127         return ret;
 128 }
 129
 130 static inline unsigned long *fetch_reg_addr(unsigned int reg, struct pt_regs *regs)
 131 {
 132         struct reg_window32 *win;
 133
 134         if(reg < 16)
 135                 return &regs->u_regs[reg];
 136         win = (struct reg_window32 *) regs->u_regs[UREG_FP];
 137         return &win->locals[reg - 16];
 138 }
 139
 140 static unsigned long compute_effective_address(struct pt_regs *regs,
 141                                                unsigned int insn)
 142 {
 143         unsigned int rs1 = (insn >> 14) & 0x1f;
 144         unsigned int rs2 = insn & 0x1f;
 145         unsigned int rd = (insn >> 25) & 0x1f;
 146
 147         if(insn & 0x2000) {
 148                 maybe_flush_windows(rs1, 0, rd);
 149                 return (fetch_reg(rs1, regs) + sign_extend_imm13(insn));
 150         } else {
 151                 maybe_flush_windows(rs1, rs2, rd);
 152                 return (fetch_reg(rs1, regs) + fetch_reg(rs2, regs));
 153         }
 154 }
 155
 156 unsigned long safe_compute_effective_address(struct pt_regs *regs,
 157                                              unsigned int insn)
 158 {
 159         unsigned int rs1 = (insn >> 14) & 0x1f;
 160         unsigned int rs2 = insn & 0x1f;
 161         unsigned int rd = (insn >> 25) & 0x1f;
 162
 163         if(insn & 0x2000) {
 164                 maybe_flush_windows(rs1, 0, rd);
 165                 return (safe_fetch_reg(rs1, regs) + sign_extend_imm13(insn));
 166         } else {
 167                 maybe_flush_windows(rs1, rs2, rd);
 168                 return (safe_fetch_reg(rs1, regs) + safe_fetch_reg(rs2, regs));
 169         }
 170 }
 171
 172 /* This is just to make gcc think panic does return... */
 173 static void unaligned_panic(char *str)
 174 {
 175         panic(str);
 176 }
 177
 178 /* una_asm.S */
 179 extern int do_int_load(unsigned long *dest_reg, int size,
 180                        unsigned long *saddr, int is_signed);
 181 extern int __do_int_store(unsigned long *dst_addr, int size,
 182                           unsigned long *src_val);
 183
 184 static int do_int_store(int reg_num, int size, unsigned long *dst_addr,
 185                         struct pt_regs *regs)
 186 {
 187         unsigned long zero[2] = { 0, 0 };
 188         unsigned long *src_val;
 189
 190         if (reg_num)
 191                 src_val = fetch_reg_addr(reg_num, regs);
 192         else {
 193                 src_val = &zero[0];
 194                 if (size == 8)
 195                         zero[1] = fetch_reg(1, regs);
 196         }
 197         return __do_int_store(dst_addr, size, src_val);
 198 }
 199
 200 extern void smp_capture(void);
 201 extern void smp_release(void);
 202
 203 static inline void advance(struct pt_regs *regs)
 204 {
 205         regs->pc   = regs->npc;
 206         regs->npc += 4;
 207 }
 208
 209 static inline int floating_point_load_or_store_p(unsigned int insn)
 210 {
 211         return (insn >> 24) & 1;
 212 }
 213
 214 static inline int ok_for_kernel(unsigned int insn)
 215 {
 216         return !floating_point_load_or_store_p(insn);
 217 }
 218
 219 static void kernel_mna_trap_fault(struct pt_regs *regs, unsigned int insn)
 220 {
 221         unsigned long g2 = regs->u_regs [UREG_G2];
 222         unsigned long fixup = search_extables_range(regs->pc, &g2);
 223
 224         if (!fixup) {
 225                 unsigned long address = compute_effective_address(regs, insn);
 226                 if(address < PAGE_SIZE) {
 227                         printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference in mna handler");
 228                 } else
 229                         printk(KERN_ALERT "Unable to handle kernel paging request in mna handler");
 230                 printk(KERN_ALERT " at virtual address %08lx\n",address);
 231                 printk(KERN_ALERT "current->{mm,active_mm}->context = %08lx\n",
 232                         (current->mm ? current->mm->context :
 233                         current->active_mm->context));
 234                 printk(KERN_ALERT "current->{mm,active_mm}->pgd = %08lx\n",
 235                         (current->mm ? (unsigned long) current->mm->pgd :
 236                         (unsigned long) current->active_mm->pgd));
 237                 die_if_kernel("Oops", regs);
 238                 /* Not reached */
 239         }
 240         regs->pc = fixup;
 241         regs->npc = regs->pc + 4;
 242         regs->u_regs [UREG_G2] = g2;
 243 }
 244
 245 asmlinkage void kernel_unaligned_trap(struct pt_regs *regs, unsigned int insn)
 246 {
 247         enum direction dir = decode_direction(insn);
 248         int size = decode_access_size(insn);
 249
 250         if(!ok_for_kernel(insn) || dir == both) {
 251                 printk("Unsupported unaligned load/store trap for kernel at <%08lx>.\n",
 252                        regs->pc);
 253                 unaligned_panic("Wheee. Kernel does fpu/atomic unaligned load/store.");
 254         } else {
 255                 unsigned long addr = compute_effective_address(regs, insn);
 256                 int err;
 257
 258 #ifdef DEBUG_MNA
 259                 printk("KMNA: pc=%08lx [dir=%s addr=%08lx size=%d] retpc[%08lx]\n",
 260                        regs->pc, dirstrings[dir], addr, size, regs->u_regs[UREG_RETPC]);
 261 #endif
 262                 switch (dir) {
 263                 case load:
 264                         err = do_int_load(fetch_reg_addr(((insn>>25)&0x1f),
 265                                                          regs),
 266                                           size, (unsigned long *) addr,
 267                                           decode_signedness(insn));
 268                         break;
 269
 270                 case store:
 271                         err = do_int_store(((insn>>25)&0x1f), size,
 272                                            (unsigned long *) addr, regs);
 273                         break;
 274                 default:
 275                         panic("Impossible kernel unaligned trap.");
 276                         /* Not reached... */
 277                 }
 278                 if (err)
 279                         kernel_mna_trap_fault(regs, insn);
 280                 else
 281                         advance(regs);
 282         }
 283 }
 284
 285 static inline int ok_for_user(struct pt_regs *regs, unsigned int insn,
 286                               enum direction dir)
 287 {
 288         unsigned int reg;
 289         int check = (dir == load) ? VERIFY_READ : VERIFY_WRITE;
 290         int size = ((insn >> 19) & 3) == 3 ? 8 : 4;
 291
 292         if ((regs->pc | regs->npc) & 3)
 293                 return 0;
 294
 295         /* Must access_ok() in all the necessary places. */
 296 #define WINREG_ADDR(regnum) \
 297         ((void __user *)(((unsigned long *)regs->u_regs[UREG_FP])+(regnum)))
 298
 299         reg = (insn >> 25) & 0x1f;
 300         if (reg >= 16) {
 301                 if (!access_ok(check, WINREG_ADDR(reg - 16), size))
 302                         return -EFAULT;
 303         }
 304         reg = (insn >> 14) & 0x1f;
 305         if (reg >= 16) {
 306                 if (!access_ok(check, WINREG_ADDR(reg - 16), size))
 307                         return -EFAULT;
 308         }
 309         if (!(insn & 0x2000)) {
 310                 reg = (insn & 0x1f);
 311                 if (reg >= 16) {
 312                         if (!access_ok(check, WINREG_ADDR(reg - 16), size))
 313                                 return -EFAULT;
 314                 }
 315         }
 316 #undef WINREG_ADDR
 317         return 0;
 318 }
 319
 320 static void user_mna_trap_fault(struct pt_regs *regs, unsigned int insn)
 321 {
 322         siginfo_t info;
 323
 324         info.si_signo = SIGBUS;
 325         info.si_errno = 0;
 326         info.si_code = BUS_ADRALN;
 327         info.si_addr = (void __user *)safe_compute_effective_address(regs, insn);
 328         info.si_trapno = 0;
 329         send_sig_info(SIGBUS, &info, current);
 330 }
 331
 332 asmlinkage void user_unaligned_trap(struct pt_regs *regs, unsigned int insn)
 333 {
 334         enum direction dir;
 335
 336         lock_kernel();
 337         if(!(current->thread.flags & SPARC_FLAG_UNALIGNED) ||
 338            (((insn >> 30) & 3) != 3))
 339                 goto kill_user;
 340         dir = decode_direction(insn);
 341         if(!ok_for_user(regs, insn, dir)) {
 342                 goto kill_user;
 343         } else {
 344                 int err, size = decode_access_size(insn);
 345                 unsigned long addr;
 346
 347                 if(floating_point_load_or_store_p(insn)) {
 348                         printk("User FPU load/store unaligned unsupported.\n");
 349                         goto kill_user;
 350                 }
 351
 352                 addr = compute_effective_address(regs, insn);
 353                 switch(dir) {
 354                 case load:
 355                         err = do_int_load(fetch_reg_addr(((insn>>25)&0x1f),
 356                                                          regs),
 357                                           size, (unsigned long *) addr,
 358                                           decode_signedness(insn));
 359                         break;
 360
 361                 case store:
 362                         err = do_int_store(((insn>>25)&0x1f), size,
 363                                            (unsigned long *) addr, regs);
 364                         break;
 365
 366                 case both:
 367                         /*
 368                          * This was supported in 2.4. However, we question
 369                          * the value of SWAP instruction across word boundaries.
 370                          */
 371                         printk("Unaligned SWAP unsupported.\n");
 372                         err = -EFAULT;
 373                         break;
 374
 375                 default:
 376                         unaligned_panic("Impossible user unaligned trap.");
 377                         goto out;
 378                 }
 379                 if (err)
 380                         goto kill_user;
 381                 else
 382                         advance(regs);
 383                 goto out;
 384         }
 385
 386 kill_user:
 387         user_mna_trap_fault(regs, insn);
 388 out:
 389         unlock_kernel();
 390 }