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 #include <linux/perf_event.h>
  21
  22 enum 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
  31 static 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 */
  46 static 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 */
  64 static inline int decode_signedness(unsigned int insn)
  65 {
  66         return (insn & 0x400000);
  67 }
  68
  69 static 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
  86 static inline int sign_extend_imm13(int imm)
  87 {
  88         return imm << 19 >> 19;
  89 }
  90
  91 static 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
 103 static 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
 123 static 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 &regs->u_regs[reg];
 129         win = (struct reg_window32 *) regs->u_regs[UREG_FP];
 130         return &win->locals[reg - 16];
 131 }
 132
 133 static 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
 149 unsigned 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... */
 166 static void unaligned_panic(char *str)
 167 {
 168         panic(str);
 169 }
 170
 171 /* una_asm.S */
 172 extern int do_int_load(unsigned long *dest_reg, int size,
 173                        unsigned long *saddr, int is_signed);
 174 extern int __do_int_store(unsigned long *dst_addr, int size,
 175                           unsigned long *src_val);
 176
 177 static 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
 193 extern void smp_capture(void);
 194 extern void smp_release(void);
 195
 196 static inline void advance(struct pt_regs *regs)
 197 {
 198         regs->pc   = regs->npc;
 199         regs->npc += 4;
 200 }
 201
 202 static inline int floating_point_load_or_store_p(unsigned int insn)
 203 {
 204         return (insn >> 24) & 1;
 205 }
 206
 207 static inline int ok_for_kernel(unsigned int insn)
 208 {
 209         return !floating_point_load_or_store_p(insn);
 210 }
 211
 212 static 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
 238 asmlinkage 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
 275 static 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
 310 static 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
 322 asmlinkage 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
 376 kill_user:
 377         user_mna_trap_fault(regs, insn);
 378 out:
 379         ;
 380 }