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