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 <asm/ptrace.h>
  14 #include <asm/processor.h>
  15 #include <asm/uaccess.h>
  16 #include <linux/smp.h>
  17 #include <linux/perf_event.h>
  18
  19 enum direction {
  20         load,    /* ld, ldd, ldh, ldsh */
  21         store,   /* st, std, sth, stsh */
  22         both,    /* Swap, ldstub, etc. */
  23         fpload,
  24         fpstore,
  25         invalid,
  26 };
  27
  28 static inline enum direction decode_direction(unsigned int insn)
  29 {
  30         unsigned long tmp = (insn >> 21) & 1;
  31
  32         if(!tmp)
  33                 return load;
  34         else {
  35                 if(((insn>>19)&0x3f) == 15)
  36                         return both;
  37                 else
  38                         return store;
  39         }
  40 }
  41
  42 /* 8 = double-word, 4 = word, 2 = half-word */
  43 static inline int decode_access_size(unsigned int insn)
  44 {
  45         insn = (insn >> 19) & 3;
  46
  47         if(!insn)
  48                 return 4;
  49         else if(insn == 3)
  50                 return 8;
  51         else if(insn == 2)
  52                 return 2;
  53         else {
  54                 printk("Impossible unaligned trap. insn=%08x\n", insn);
  55                 die_if_kernel("Byte sized unaligned access?!?!", current->thread.kregs);
  56                 return 4; /* just to keep gcc happy. */
  57         }
  58 }
  59
  60 /* 0x400000 = signed, 0 = unsigned */
  61 static inline int decode_signedness(unsigned int insn)
  62 {
  63         return (insn & 0x400000);
  64 }
  65
  66 static inline void maybe_flush_windows(unsigned int rs1, unsigned int rs2,
  67                                        unsigned int rd)
  68 {
  69         if(rs2 >= 16 || rs1 >= 16 || rd >= 16) {
  70                 /* Wheee... */
  71                 __asm__ __volatile__("save %sp, -0x40, %sp\n\t"
  72                                      "save %sp, -0x40, %sp\n\t"
  73                                      "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                                      "restore; restore; restore; restore;\n\t"
  79                                      "restore; restore; restore;\n\t");
  80         }
  81 }
  82
  83 static inline int sign_extend_imm13(int imm)
  84 {
  85         return imm << 19 >> 19;
  86 }
  87
  88 static inline unsigned long fetch_reg(unsigned int reg, struct pt_regs *regs)
  89 {
  90         struct reg_window32 *win;
  91
  92         if(reg < 16)
  93                 return (!reg ? 0 : regs->u_regs[reg]);
  94
  95         /* Ho hum, the slightly complicated case. */
  96         win = (struct reg_window32 *) regs->u_regs[UREG_FP];
  97         return win->locals[reg - 16]; /* yes, I know what this does... */
  98 }
  99
 100 static inline unsigned long safe_fetch_reg(unsigned int reg, struct pt_regs *regs)
 101 {
 102         struct reg_window32 __user *win;
 103         unsigned long ret;
 104
 105         if (reg < 16)
 106                 return (!reg ? 0 : regs->u_regs[reg]);
 107
 108         /* Ho hum, the slightly complicated case. */
 109         win = (struct reg_window32 __user *) regs->u_regs[UREG_FP];
 110
 111         if ((unsigned long)win & 3)
 112                 return -1;
 113
 114         if (get_user(ret, &win->locals[reg - 16]))
 115                 return -1;
 116
 117         return ret;
 118 }
 119
 120 static inline unsigned long *fetch_reg_addr(unsigned int reg, struct pt_regs *regs)
 121 {
 122         struct reg_window32 *win;
 123
 124         if(reg < 16)
 125                 return &regs->u_regs[reg];
 126         win = (struct reg_window32 *) regs->u_regs[UREG_FP];
 127         return &win->locals[reg - 16];
 128 }
 129
 130 static unsigned long compute_effective_address(struct pt_regs *regs,
 131                                                unsigned int insn)
 132 {
 133         unsigned int rs1 = (insn >> 14) & 0x1f;
 134         unsigned int rs2 = insn & 0x1f;
 135         unsigned int rd = (insn >> 25) & 0x1f;
 136
 137         if(insn & 0x2000) {
 138                 maybe_flush_windows(rs1, 0, rd);
 139                 return (fetch_reg(rs1, regs) + sign_extend_imm13(insn));
 140         } else {
 141                 maybe_flush_windows(rs1, rs2, rd);
 142                 return (fetch_reg(rs1, regs) + fetch_reg(rs2, regs));
 143         }
 144 }
 145
 146 unsigned long safe_compute_effective_address(struct pt_regs *regs,
 147                                              unsigned int insn)
 148 {
 149         unsigned int rs1 = (insn >> 14) & 0x1f;
 150         unsigned int rs2 = insn & 0x1f;
 151         unsigned int rd = (insn >> 25) & 0x1f;
 152
 153         if(insn & 0x2000) {
 154                 maybe_flush_windows(rs1, 0, rd);
 155                 return (safe_fetch_reg(rs1, regs) + sign_extend_imm13(insn));
 156         } else {
 157                 maybe_flush_windows(rs1, rs2, rd);
 158                 return (safe_fetch_reg(rs1, regs) + safe_fetch_reg(rs2, regs));
 159         }
 160 }
 161
 162 /* This is just to make gcc think panic does return... */
 163 static void unaligned_panic(char *str)
 164 {
 165         panic(str);
 166 }
 167
 168 /* una_asm.S */
 169 extern int do_int_load(unsigned long *dest_reg, int size,
 170                        unsigned long *saddr, int is_signed);
 171 extern int __do_int_store(unsigned long *dst_addr, int size,
 172                           unsigned long *src_val);
 173
 174 static int do_int_store(int reg_num, int size, unsigned long *dst_addr,
 175                         struct pt_regs *regs)
 176 {
 177         unsigned long zero[2] = { 0, 0 };
 178         unsigned long *src_val;
 179
 180         if (reg_num)
 181                 src_val = fetch_reg_addr(reg_num, regs);
 182         else {
 183                 src_val = &zero[0];
 184                 if (size == 8)
 185                         zero[1] = fetch_reg(1, regs);
 186         }
 187         return __do_int_store(dst_addr, size, src_val);
 188 }
 189
 190 extern void smp_capture(void);
 191 extern void smp_release(void);
 192
 193 static inline void advance(struct pt_regs *regs)
 194 {
 195         regs->pc   = regs->npc;
 196         regs->npc += 4;
 197 }
 198
 199 static inline int floating_point_load_or_store_p(unsigned int insn)
 200 {
 201         return (insn >> 24) & 1;
 202 }
 203
 204 static inline int ok_for_kernel(unsigned int insn)
 205 {
 206         return !floating_point_load_or_store_p(insn);
 207 }
 208
 209 static void kernel_mna_trap_fault(struct pt_regs *regs, unsigned int insn)
 210 {
 211         unsigned long g2 = regs->u_regs [UREG_G2];
 212         unsigned long fixup = search_extables_range(regs->pc, &g2);
 213
 214         if (!fixup) {
 215                 unsigned long address = compute_effective_address(regs, insn);
 216                 if(address < PAGE_SIZE) {
 217                         printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference in mna handler");
 218                 } else
 219                         printk(KERN_ALERT "Unable to handle kernel paging request in mna handler");
 220                 printk(KERN_ALERT " at virtual address %08lx\n",address);
 221                 printk(KERN_ALERT "current->{mm,active_mm}->context = %08lx\n",
 222                         (current->mm ? current->mm->context :
 223                         current->active_mm->context));
 224                 printk(KERN_ALERT "current->{mm,active_mm}->pgd = %08lx\n",
 225                         (current->mm ? (unsigned long) current->mm->pgd :
 226                         (unsigned long) current->active_mm->pgd));
 227                 die_if_kernel("Oops", regs);
 228                 /* Not reached */
 229         }
 230         regs->pc = fixup;
 231         regs->npc = regs->pc + 4;
 232         regs->u_regs [UREG_G2] = g2;
 233 }
 234
 235 asmlinkage void kernel_unaligned_trap(struct pt_regs *regs, unsigned int insn)
 236 {
 237         enum direction dir = decode_direction(insn);
 238         int size = decode_access_size(insn);
 239
 240         if(!ok_for_kernel(insn) || dir == both) {
 241                 printk("Unsupported unaligned load/store trap for kernel at <%08lx>.\n",
 242                        regs->pc);
 243                 unaligned_panic("Wheee. Kernel does fpu/atomic unaligned load/store.");
 244         } else {
 245                 unsigned long addr = compute_effective_address(regs, insn);
 246                 int err;
 247
 248                 perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, regs, addr);
 249                 switch (dir) {
 250                 case load:
 251                         err = do_int_load(fetch_reg_addr(((insn>>25)&0x1f),
 252                                                          regs),
 253                                           size, (unsigned long *) addr,
 254                                           decode_signedness(insn));
 255                         break;
 256
 257                 case store:
 258                         err = do_int_store(((insn>>25)&0x1f), size,
 259                                            (unsigned long *) addr, regs);
 260                         break;
 261                 default:
 262                         panic("Impossible kernel unaligned trap.");
 263                         /* Not reached... */
 264                 }
 265                 if (err)
 266                         kernel_mna_trap_fault(regs, insn);
 267                 else
 268                         advance(regs);
 269         }
 270 }
 271
 272 static inline int ok_for_user(struct pt_regs *regs, unsigned int insn,
 273                               enum direction dir)
 274 {
 275         unsigned int reg;
 276         int check = (dir == load) ? VERIFY_READ : VERIFY_WRITE;
 277         int size = ((insn >> 19) & 3) == 3 ? 8 : 4;
 278
 279         if ((regs->pc | regs->npc) & 3)
 280                 return 0;
 281
 282         /* Must access_ok() in all the necessary places. */
 283 #define WINREG_ADDR(regnum) \
 284         ((void __user *)(((unsigned long *)regs->u_regs[UREG_FP])+(regnum)))
 285
 286         reg = (insn >> 25) & 0x1f;
 287         if (reg >= 16) {
 288                 if (!access_ok(check, WINREG_ADDR(reg - 16), size))
 289                         return -EFAULT;
 290         }
 291         reg = (insn >> 14) & 0x1f;
 292         if (reg >= 16) {
 293                 if (!access_ok(check, WINREG_ADDR(reg - 16), size))
 294                         return -EFAULT;
 295         }
 296         if (!(insn & 0x2000)) {
 297                 reg = (insn & 0x1f);
 298                 if (reg >= 16) {
 299                         if (!access_ok(check, WINREG_ADDR(reg - 16), size))
 300                                 return -EFAULT;
 301                 }
 302         }
 303 #undef WINREG_ADDR
 304         return 0;
 305 }
 306
 307 static void user_mna_trap_fault(struct pt_regs *regs, unsigned int insn)
 308 {
 309         siginfo_t info;
 310
 311         info.si_signo = SIGBUS;
 312         info.si_errno = 0;
 313         info.si_code = BUS_ADRALN;
 314         info.si_addr = (void __user *)safe_compute_effective_address(regs, insn);
 315         info.si_trapno = 0;
 316         send_sig_info(SIGBUS, &info, current);
 317 }
 318
 319 asmlinkage void user_unaligned_trap(struct pt_regs *regs, unsigned int insn)
 320 {
 321         enum direction dir;
 322
 323         if(!(current->thread.flags & SPARC_FLAG_UNALIGNED) ||
 324            (((insn >> 30) & 3) != 3))
 325                 goto kill_user;
 326         dir = decode_direction(insn);
 327         if(!ok_for_user(regs, insn, dir)) {
 328                 goto kill_user;
 329         } else {
 330                 int err, size = decode_access_size(insn);
 331                 unsigned long addr;
 332
 333                 if(floating_point_load_or_store_p(insn)) {
 334                         printk("User FPU load/store unaligned unsupported.\n");
 335                         goto kill_user;
 336                 }
 337
 338                 addr = compute_effective_address(regs, insn);
 339                 perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, regs, addr);
 340                 switch(dir) {
 341                 case load:
 342                         err = do_int_load(fetch_reg_addr(((insn>>25)&0x1f),
 343                                                          regs),
 344                                           size, (unsigned long *) addr,
 345                                           decode_signedness(insn));
 346                         break;
 347
 348                 case store:
 349                         err = do_int_store(((insn>>25)&0x1f), size,
 350                                            (unsigned long *) addr, regs);
 351                         break;
 352
 353                 case both:
 354                         /*
 355                          * This was supported in 2.4. However, we question
 356                          * the value of SWAP instruction across word boundaries.
 357                          */
 358                         printk("Unaligned SWAP unsupported.\n");
 359                         err = -EFAULT;
 360                         break;
 361
 362                 default:
 363                         unaligned_panic("Impossible user unaligned trap.");
 364                         goto out;
 365                 }
 366                 if (err)
 367                         goto kill_user;
 368                 else
 369                         advance(regs);
 370                 goto out;
 371         }
 372
 373 kill_user:
 374         user_mna_trap_fault(regs, insn);
 375 out:
 376         ;
 377 }