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/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 &regs->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 }