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/signal.h>
  12 #include <linux/mm.h>
  13 #include <asm/ptrace.h>
  14 #include <asm/processor.h>
  15 #include <linux/uaccess.h>
  16 #include <linux/smp.h>
  17 #include <linux/perf_event.h>
  18
  19 #include <asm/setup.h>
  20
  21 #include "kernel.h"
  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 static inline enum direction decode_direction(unsigned int insn)
  33 {
  34         unsigned long tmp = (insn >> 21) & 1;
  35
  36         if(!tmp)
  37                 return load;
  38         else {
  39                 if(((insn>>19)&0x3f) == 15)
  40                         return both;
  41                 else
  42                         return store;
  43         }
  44 }
  45
  46 /* 8 = double-word, 4 = word, 2 = half-word */
  47 static inline int decode_access_size(unsigned int insn)
  48 {
  49         insn = (insn >> 19) & 3;
  50
  51         if(!insn)
  52                 return 4;
  53         else if(insn == 3)
  54                 return 8;
  55         else if(insn == 2)
  56                 return 2;
  57         else {
  58                 printk("Impossible unaligned trap. insn=%08x\n", insn);
  59                 die_if_kernel("Byte sized unaligned access?!?!", current->thread.kregs);
  60                 return 4; /* just to keep gcc happy. */
  61         }
  62 }
  63
  64 /* 0x400000 = signed, 0 = unsigned */
  65 static inline int decode_signedness(unsigned int insn)
  66 {
  67         return (insn & 0x400000);
  68 }
  69
  70 static inline void maybe_flush_windows(unsigned int rs1, unsigned int rs2,
  71                                        unsigned int rd)
  72 {
  73         if(rs2 >= 16 || rs1 >= 16 || rd >= 16) {
  74                 /* Wheee... */
  75                 __asm__ __volatile__("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                                      "save %sp, -0x40, %sp\n\t"
  82                                      "restore; restore; restore; restore;\n\t"
  83                                      "restore; restore; restore;\n\t");
  84         }
  85 }
  86
  87 static inline int sign_extend_imm13(int imm)
  88 {
  89         return imm << 19 >> 19;
  90 }
  91
  92 static inline unsigned long fetch_reg(unsigned int reg, struct pt_regs *regs)
  93 {
  94         struct reg_window32 *win;
  95
  96         if(reg < 16)
  97                 return (!reg ? 0 : regs->u_regs[reg]);
  98
  99         /* Ho hum, the slightly complicated case. */
 100         win = (struct reg_window32 *) regs->u_regs[UREG_FP];
 101         return win->locals[reg - 16]; /* yes, I know what this does... */
 102 }
 103
 104 static inline unsigned long safe_fetch_reg(unsigned int reg, struct pt_regs *regs)
 105 {
 106         struct reg_window32 __user *win;
 107         unsigned long ret;
 108
 109         if (reg < 16)
 110                 return (!reg ? 0 : regs->u_regs[reg]);
 111
 112         /* Ho hum, the slightly complicated case. */
 113         win = (struct reg_window32 __user *) regs->u_regs[UREG_FP];
 114
 115         if ((unsigned long)win & 3)
 116                 return -1;
 117
 118         if (get_user(ret, &win->locals[reg - 16]))
 119                 return -1;
 120
 121         return ret;
 122 }
 123
 124 static inline unsigned long *fetch_reg_addr(unsigned int reg, struct pt_regs *regs)
 125 {
 126         struct reg_window32 *win;
 127
 128         if(reg < 16)
 129                 return &regs->u_regs[reg];
 130         win = (struct reg_window32 *) regs->u_regs[UREG_FP];
 131         return &win->locals[reg - 16];
 132 }
 133
 134 static unsigned long compute_effective_address(struct pt_regs *regs,
 135                                                unsigned int insn)
 136 {
 137         unsigned int rs1 = (insn >> 14) & 0x1f;
 138         unsigned int rs2 = insn & 0x1f;
 139         unsigned int rd = (insn >> 25) & 0x1f;
 140
 141         if(insn & 0x2000) {
 142                 maybe_flush_windows(rs1, 0, rd);
 143                 return (fetch_reg(rs1, regs) + sign_extend_imm13(insn));
 144         } else {
 145                 maybe_flush_windows(rs1, rs2, rd);
 146                 return (fetch_reg(rs1, regs) + fetch_reg(rs2, regs));
 147         }
 148 }
 149
 150 unsigned long safe_compute_effective_address(struct pt_regs *regs,
 151                                              unsigned int insn)
 152 {
 153         unsigned int rs1 = (insn >> 14) & 0x1f;
 154         unsigned int rs2 = insn & 0x1f;
 155         unsigned int rd = (insn >> 25) & 0x1f;
 156
 157         if(insn & 0x2000) {
 158                 maybe_flush_windows(rs1, 0, rd);
 159                 return (safe_fetch_reg(rs1, regs) + sign_extend_imm13(insn));
 160         } else {
 161                 maybe_flush_windows(rs1, rs2, rd);
 162                 return (safe_fetch_reg(rs1, regs) + safe_fetch_reg(rs2, regs));
 163         }
 164 }
 165
 166 /* This is just to make gcc think panic does return... */
 167 static void unaligned_panic(char *str)
 168 {
 169         panic("%s", str);
 170 }
 171
 172 /* una_asm.S */
 173 extern int do_int_load(unsigned long *dest_reg, int size,
 174                        unsigned long *saddr, int is_signed);
 175 extern int __do_int_store(unsigned long *dst_addr, int size,
 176                           unsigned long *src_val);
 177
 178 static int do_int_store(int reg_num, int size, unsigned long *dst_addr,
 179                         struct pt_regs *regs)
 180 {
 181         unsigned long zero[2] = { 0, 0 };
 182         unsigned long *src_val;
 183
 184         if (reg_num)
 185                 src_val = fetch_reg_addr(reg_num, regs);
 186         else {
 187                 src_val = &zero[0];
 188                 if (size == 8)
 189                         zero[1] = fetch_reg(1, regs);
 190         }
 191         return __do_int_store(dst_addr, size, src_val);
 192 }
 193
 194 extern void smp_capture(void);
 195 extern void smp_release(void);
 196
 197 static inline void advance(struct pt_regs *regs)
 198 {
 199         regs->pc   = regs->npc;
 200         regs->npc += 4;
 201 }
 202
 203 static inline int floating_point_load_or_store_p(unsigned int insn)
 204 {
 205         return (insn >> 24) & 1;
 206 }
 207
 208 static inline int ok_for_kernel(unsigned int insn)
 209 {
 210         return !floating_point_load_or_store_p(insn);
 211 }
 212
 213 static void kernel_mna_trap_fault(struct pt_regs *regs, unsigned int insn)
 214 {
 215         unsigned long g2 = regs->u_regs [UREG_G2];
 216         unsigned long fixup = search_extables_range(regs->pc, &g2);
 217
 218         if (!fixup) {
 219                 unsigned long address = compute_effective_address(regs, insn);
 220                 if(address < PAGE_SIZE) {
 221                         printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference in mna handler");
 222                 } else
 223                         printk(KERN_ALERT "Unable to handle kernel paging request in mna handler");
 224                 printk(KERN_ALERT " at virtual address %08lx\n",address);
 225                 printk(KERN_ALERT "current->{mm,active_mm}->context = %08lx\n",
 226                         (current->mm ? current->mm->context :
 227                         current->active_mm->context));
 228                 printk(KERN_ALERT "current->{mm,active_mm}->pgd = %08lx\n",
 229                         (current->mm ? (unsigned long) current->mm->pgd :
 230                         (unsigned long) current->active_mm->pgd));
 231                 die_if_kernel("Oops", regs);
 232                 /* Not reached */
 233         }
 234         regs->pc = fixup;
 235         regs->npc = regs->pc + 4;
 236         regs->u_regs [UREG_G2] = g2;
 237 }
 238
 239 asmlinkage void kernel_unaligned_trap(struct pt_regs *regs, unsigned int insn)
 240 {
 241         enum direction dir = decode_direction(insn);
 242         int size = decode_access_size(insn);
 243
 244         if(!ok_for_kernel(insn) || dir == both) {
 245                 printk("Unsupported unaligned load/store trap for kernel at <%08lx>.\n",
 246                        regs->pc);
 247                 unaligned_panic("Wheee. Kernel does fpu/atomic unaligned load/store.");
 248         } else {
 249                 unsigned long addr = compute_effective_address(regs, insn);
 250                 int err;
 251
 252                 perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, regs, addr);
 253                 switch (dir) {
 254                 case load:
 255                         err = do_int_load(fetch_reg_addr(((insn>>25)&0x1f),
 256                                                          regs),
 257                                           size, (unsigned long *) addr,
 258                                           decode_signedness(insn));
 259                         break;
 260
 261                 case store:
 262                         err = do_int_store(((insn>>25)&0x1f), size,
 263                                            (unsigned long *) addr, regs);
 264                         break;
 265                 default:
 266                         panic("Impossible kernel unaligned trap.");
 267                         /* Not reached... */
 268                 }
 269                 if (err)
 270                         kernel_mna_trap_fault(regs, insn);
 271                 else
 272                         advance(regs);
 273         }
 274 }
 275
 276 static inline int ok_for_user(struct pt_regs *regs, unsigned int insn,
 277                               enum direction dir)
 278 {
 279         unsigned int reg;
 280         int check = (dir == load) ? VERIFY_READ : VERIFY_WRITE;
 281         int size = ((insn >> 19) & 3) == 3 ? 8 : 4;
 282
 283         if ((regs->pc | regs->npc) & 3)
 284                 return 0;
 285
 286         /* Must access_ok() in all the necessary places. */
 287 #define WINREG_ADDR(regnum) \
 288         ((void __user *)(((unsigned long *)regs->u_regs[UREG_FP])+(regnum)))
 289
 290         reg = (insn >> 25) & 0x1f;
 291         if (reg >= 16) {
 292                 if (!access_ok(check, WINREG_ADDR(reg - 16), size))
 293                         return -EFAULT;
 294         }
 295         reg = (insn >> 14) & 0x1f;
 296         if (reg >= 16) {
 297                 if (!access_ok(check, WINREG_ADDR(reg - 16), size))
 298                         return -EFAULT;
 299         }
 300         if (!(insn & 0x2000)) {
 301                 reg = (insn & 0x1f);
 302                 if (reg >= 16) {
 303                         if (!access_ok(check, WINREG_ADDR(reg - 16), size))
 304                                 return -EFAULT;
 305                 }
 306         }
 307 #undef WINREG_ADDR
 308         return 0;
 309 }
 310
 311 static void user_mna_trap_fault(struct pt_regs *regs, unsigned int insn)
 312 {
 313         siginfo_t info;
 314
 315         info.si_signo = SIGBUS;
 316         info.si_errno = 0;
 317         info.si_code = BUS_ADRALN;
 318         info.si_addr = (void __user *)safe_compute_effective_address(regs, insn);
 319         info.si_trapno = 0;
 320         send_sig_info(SIGBUS, &info, current);
 321 }
 322
 323 asmlinkage void user_unaligned_trap(struct pt_regs *regs, unsigned int insn)
 324 {
 325         enum direction dir;
 326
 327         if(!(current->thread.flags & SPARC_FLAG_UNALIGNED) ||
 328            (((insn >> 30) & 3) != 3))
 329                 goto kill_user;
 330         dir = decode_direction(insn);
 331         if(!ok_for_user(regs, insn, dir)) {
 332                 goto kill_user;
 333         } else {
 334                 int err, size = decode_access_size(insn);
 335                 unsigned long addr;
 336
 337                 if(floating_point_load_or_store_p(insn)) {
 338                         printk("User FPU load/store unaligned unsupported.\n");
 339                         goto kill_user;
 340                 }
 341
 342                 addr = compute_effective_address(regs, insn);
 343                 perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, regs, addr);
 344                 switch(dir) {
 345                 case load:
 346                         err = do_int_load(fetch_reg_addr(((insn>>25)&0x1f),
 347                                                          regs),
 348                                           size, (unsigned long *) addr,
 349                                           decode_signedness(insn));
 350                         break;
 351
 352                 case store:
 353                         err = do_int_store(((insn>>25)&0x1f), size,
 354                                            (unsigned long *) addr, regs);
 355                         break;
 356
 357                 case both:
 358                         /*
 359                          * This was supported in 2.4. However, we question
 360                          * the value of SWAP instruction across word boundaries.
 361                          */
 362                         printk("Unaligned SWAP unsupported.\n");
 363                         err = -EFAULT;
 364                         break;
 365
 366                 default:
 367                         unaligned_panic("Impossible user unaligned trap.");
 368                         goto out;
 369                 }
 370                 if (err)
 371                         goto kill_user;
 372                 else
 373                         advance(regs);
 374                 goto out;
 375         }
 376
 377 kill_user:
 378         user_mna_trap_fault(regs, insn);
 379 out:
 380         ;
 381 }