arch/s390/kernel/traps.c

   1 /*
   2  *  S390 version
   3  *    Copyright IBM Corp. 1999, 2000
   4  *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
   5  *               Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com),
   6  *
   7  *  Derived from "arch/i386/kernel/traps.c"
   8  *    Copyright (C) 1991, 1992 Linus Torvalds
   9  */
  10
  11 /*
  12  * 'Traps.c' handles hardware traps and faults after we have saved some
  13  * state in 'asm.s'.
  14  */
  15 #include <linux/kprobes.h>
  16 #include <linux/kdebug.h>
  17 #include <linux/module.h>
  18 #include <linux/ptrace.h>
  19 #include <linux/sched.h>
  20 #include <linux/mm.h>
  21 #include <linux/slab.h>
  22 #include <asm/switch_to.h>
  23 #include "entry.h"
  24
  25 int show_unhandled_signals = 1;
  26
  27 static inline void __user *get_trap_ip(struct pt_regs *regs)
  28 {
  29 #ifdef CONFIG_64BIT
  30         unsigned long address;
  31
  32         if (regs->int_code & 0x200)
  33                 address = *(unsigned long *)(current->thread.trap_tdb + 24);
  34         else
  35                 address = regs->psw.addr;
  36         return (void __user *)
  37                 ((address - (regs->int_code >> 16)) & PSW_ADDR_INSN);
  38 #else
  39         return (void __user *)
  40                 ((regs->psw.addr - (regs->int_code >> 16)) & PSW_ADDR_INSN);
  41 #endif
  42 }
  43
  44 static inline void report_user_fault(struct pt_regs *regs, int signr)
  45 {
  46         if ((task_pid_nr(current) > 1) && !show_unhandled_signals)
  47                 return;
  48         if (!unhandled_signal(current, signr))
  49                 return;
  50         if (!printk_ratelimit())
  51                 return;
  52         printk("User process fault: interruption code %04x ilc:%d ",
  53                regs->int_code & 0xffff, regs->int_code >> 17);
  54         print_vma_addr("in ", regs->psw.addr & PSW_ADDR_INSN);
  55         printk("\n");
  56         show_regs(regs);
  57 }
  58
  59 int is_valid_bugaddr(unsigned long addr)
  60 {
  61         return 1;
  62 }
  63
  64 void do_report_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
  65 {
  66         siginfo_t info;
  67
  68         if (user_mode(regs)) {
  69                 info.si_signo = si_signo;
  70                 info.si_errno = 0;
  71                 info.si_code = si_code;
  72                 info.si_addr = get_trap_ip(regs);
  73                 force_sig_info(si_signo, &info, current);
  74                 report_user_fault(regs, si_signo);
  75         } else {
  76                 const struct exception_table_entry *fixup;
  77                 fixup = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
  78                 if (fixup)
  79                         regs->psw.addr = extable_fixup(fixup) | PSW_ADDR_AMODE;
  80                 else {
  81                         enum bug_trap_type btt;
  82
  83                         btt = report_bug(regs->psw.addr & PSW_ADDR_INSN, regs);
  84                         if (btt == BUG_TRAP_TYPE_WARN)
  85                                 return;
  86                         die(regs, str);
  87                 }
  88         }
  89 }
  90
  91 static void do_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
  92 {
  93         if (notify_die(DIE_TRAP, str, regs, 0,
  94                        regs->int_code, si_signo) == NOTIFY_STOP)
  95                 return;
  96         do_report_trap(regs, si_signo, si_code, str);
  97 }
  98 NOKPROBE_SYMBOL(do_trap);
  99
 100 void do_per_trap(struct pt_regs *regs)
 101 {
 102         siginfo_t info;
 103
 104         if (notify_die(DIE_SSTEP, "sstep", regs, 0, 0, SIGTRAP) == NOTIFY_STOP)
 105                 return;
 106         if (!current->ptrace)
 107                 return;
 108         info.si_signo = SIGTRAP;
 109         info.si_errno = 0;
 110         info.si_code = TRAP_HWBKPT;
 111         info.si_addr =
 112                 (void __force __user *) current->thread.per_event.address;
 113         force_sig_info(SIGTRAP, &info, current);
 114 }
 115 NOKPROBE_SYMBOL(do_per_trap);
 116
 117 void default_trap_handler(struct pt_regs *regs)
 118 {
 119         if (user_mode(regs)) {
 120                 report_user_fault(regs, SIGSEGV);
 121                 do_exit(SIGSEGV);
 122         } else
 123                 die(regs, "Unknown program exception");
 124 }
 125
 126 #define DO_ERROR_INFO(name, signr, sicode, str) \
 127 void name(struct pt_regs *regs)                 \
 128 {                                               \
 129         do_trap(regs, signr, sicode, str);      \
 130 }
 131
 132 DO_ERROR_INFO(addressing_exception, SIGILL, ILL_ILLADR,
 133               "addressing exception")
 134 DO_ERROR_INFO(execute_exception, SIGILL, ILL_ILLOPN,
 135               "execute exception")
 136 DO_ERROR_INFO(divide_exception, SIGFPE, FPE_INTDIV,
 137               "fixpoint divide exception")
 138 DO_ERROR_INFO(overflow_exception, SIGFPE, FPE_INTOVF,
 139               "fixpoint overflow exception")
 140 DO_ERROR_INFO(hfp_overflow_exception, SIGFPE, FPE_FLTOVF,
 141               "HFP overflow exception")
 142 DO_ERROR_INFO(hfp_underflow_exception, SIGFPE, FPE_FLTUND,
 143               "HFP underflow exception")
 144 DO_ERROR_INFO(hfp_significance_exception, SIGFPE, FPE_FLTRES,
 145               "HFP significance exception")
 146 DO_ERROR_INFO(hfp_divide_exception, SIGFPE, FPE_FLTDIV,
 147               "HFP divide exception")
 148 DO_ERROR_INFO(hfp_sqrt_exception, SIGFPE, FPE_FLTINV,
 149               "HFP square root exception")
 150 DO_ERROR_INFO(operand_exception, SIGILL, ILL_ILLOPN,
 151               "operand exception")
 152 DO_ERROR_INFO(privileged_op, SIGILL, ILL_PRVOPC,
 153               "privileged operation")
 154 DO_ERROR_INFO(special_op_exception, SIGILL, ILL_ILLOPN,
 155               "special operation exception")
 156
 157 #ifdef CONFIG_64BIT
 158 DO_ERROR_INFO(transaction_exception, SIGILL, ILL_ILLOPN,
 159               "transaction constraint exception")
 160 #endif
 161
 162 static inline void do_fp_trap(struct pt_regs *regs, int fpc)
 163 {
 164         int si_code = 0;
 165         /* FPC[2] is Data Exception Code */
 166         if ((fpc & 0x00000300) == 0) {
 167                 /* bits 6 and 7 of DXC are 0 iff IEEE exception */
 168                 if (fpc & 0x8000) /* invalid fp operation */
 169                         si_code = FPE_FLTINV;
 170                 else if (fpc & 0x4000) /* div by 0 */
 171                         si_code = FPE_FLTDIV;
 172                 else if (fpc & 0x2000) /* overflow */
 173                         si_code = FPE_FLTOVF;
 174                 else if (fpc & 0x1000) /* underflow */
 175                         si_code = FPE_FLTUND;
 176                 else if (fpc & 0x0800) /* inexact */
 177                         si_code = FPE_FLTRES;
 178         }
 179         do_trap(regs, SIGFPE, si_code, "floating point exception");
 180 }
 181
 182 void translation_exception(struct pt_regs *regs)
 183 {
 184         /* May never happen. */
 185         die(regs, "Translation exception");
 186 }
 187
 188 void illegal_op(struct pt_regs *regs)
 189 {
 190         siginfo_t info;
 191         __u8 opcode[6];
 192         __u16 __user *location;
 193         int is_uprobe_insn = 0;
 194         int signal = 0;
 195
 196         location = get_trap_ip(regs);
 197
 198         if (user_mode(regs)) {
 199                 if (get_user(*((__u16 *) opcode), (__u16 __user *) location))
 200                         return;
 201                 if (*((__u16 *) opcode) == S390_BREAKPOINT_U16) {
 202                         if (current->ptrace) {
 203                                 info.si_signo = SIGTRAP;
 204                                 info.si_errno = 0;
 205                                 info.si_code = TRAP_BRKPT;
 206                                 info.si_addr = location;
 207                                 force_sig_info(SIGTRAP, &info, current);
 208                         } else
 209                                 signal = SIGILL;
 210 #ifdef CONFIG_UPROBES
 211                 } else if (*((__u16 *) opcode) == UPROBE_SWBP_INSN) {
 212                         is_uprobe_insn = 1;
 213 #endif
 214 #ifdef CONFIG_MATHEMU
 215                 } else if (opcode[0] == 0xb3) {
 216                         if (get_user(*((__u16 *) (opcode+2)), location+1))
 217                                 return;
 218                         signal = math_emu_b3(opcode, regs);
 219                 } else if (opcode[0] == 0xed) {
 220                         if (get_user(*((__u32 *) (opcode+2)),
 221                                      (__u32 __user *)(location+1)))
 222                                 return;
 223                         signal = math_emu_ed(opcode, regs);
 224                 } else if (*((__u16 *) opcode) == 0xb299) {
 225                         if (get_user(*((__u16 *) (opcode+2)), location+1))
 226                                 return;
 227                         signal = math_emu_srnm(opcode, regs);
 228                 } else if (*((__u16 *) opcode) == 0xb29c) {
 229                         if (get_user(*((__u16 *) (opcode+2)), location+1))
 230                                 return;
 231                         signal = math_emu_stfpc(opcode, regs);
 232                 } else if (*((__u16 *) opcode) == 0xb29d) {
 233                         if (get_user(*((__u16 *) (opcode+2)), location+1))
 234                                 return;
 235                         signal = math_emu_lfpc(opcode, regs);
 236 #endif
 237                 } else
 238                         signal = SIGILL;
 239         }
 240         /*
 241          * We got either an illegal op in kernel mode, or user space trapped
 242          * on a uprobes illegal instruction. See if kprobes or uprobes picks
 243          * it up. If not, SIGILL.
 244          */
 245         if (is_uprobe_insn || !user_mode(regs)) {
 246                 if (notify_die(DIE_BPT, "bpt", regs, 0,
 247                                3, SIGTRAP) != NOTIFY_STOP)
 248                         signal = SIGILL;
 249         }
 250
 251 #ifdef CONFIG_MATHEMU
 252         if (signal == SIGFPE)
 253                 do_fp_trap(regs, current->thread.fp_regs.fpc);
 254         else if (signal == SIGSEGV)
 255                 do_trap(regs, signal, SEGV_MAPERR, "user address fault");
 256         else
 257 #endif
 258         if (signal)
 259                 do_trap(regs, signal, ILL_ILLOPC, "illegal operation");
 260 }
 261 NOKPROBE_SYMBOL(illegal_op);
 262
 263 #ifdef CONFIG_MATHEMU
 264 void specification_exception(struct pt_regs *regs)
 265 {
 266         __u8 opcode[6];
 267         __u16 __user *location = NULL;
 268         int signal = 0;
 269
 270         location = (__u16 __user *) get_trap_ip(regs);
 271
 272         if (user_mode(regs)) {
 273                 get_user(*((__u16 *) opcode), location);
 274                 switch (opcode[0]) {
 275                 case 0x28: /* LDR Rx,Ry   */
 276                         signal = math_emu_ldr(opcode);
 277                         break;
 278                 case 0x38: /* LER Rx,Ry   */
 279                         signal = math_emu_ler(opcode);
 280                         break;
 281                 case 0x60: /* STD R,D(X,B) */
 282                         get_user(*((__u16 *) (opcode+2)), location+1);
 283                         signal = math_emu_std(opcode, regs);
 284                         break;
 285                 case 0x68: /* LD R,D(X,B) */
 286                         get_user(*((__u16 *) (opcode+2)), location+1);
 287                         signal = math_emu_ld(opcode, regs);
 288                         break;
 289                 case 0x70: /* STE R,D(X,B) */
 290                         get_user(*((__u16 *) (opcode+2)), location+1);
 291                         signal = math_emu_ste(opcode, regs);
 292                         break;
 293                 case 0x78: /* LE R,D(X,B) */
 294                         get_user(*((__u16 *) (opcode+2)), location+1);
 295                         signal = math_emu_le(opcode, regs);
 296                         break;
 297                 default:
 298                         signal = SIGILL;
 299                         break;
 300                 }
 301         } else
 302                 signal = SIGILL;
 303
 304         if (signal == SIGFPE)
 305                 do_fp_trap(regs, current->thread.fp_regs.fpc);
 306         else if (signal)
 307                 do_trap(regs, signal, ILL_ILLOPN, "specification exception");
 308 }
 309 #else
 310 DO_ERROR_INFO(specification_exception, SIGILL, ILL_ILLOPN,
 311               "specification exception");
 312 #endif
 313
 314 #ifdef CONFIG_64BIT
 315 int alloc_vector_registers(struct task_struct *tsk)
 316 {
 317         __vector128 *vxrs;
 318         int i;
 319
 320         /* Allocate vector register save area. */
 321         vxrs = kzalloc(sizeof(__vector128) * __NUM_VXRS,
 322                        GFP_KERNEL|__GFP_REPEAT);
 323         if (!vxrs)
 324                 return -ENOMEM;
 325         preempt_disable();
 326         if (tsk == current)
 327                 save_fp_regs(tsk->thread.fp_regs.fprs);
 328         /* Copy the 16 floating point registers */
 329         for (i = 0; i < 16; i++)
 330                 *(freg_t *) &vxrs[i] = tsk->thread.fp_regs.fprs[i];
 331         tsk->thread.vxrs = vxrs;
 332         if (tsk == current) {
 333                 __ctl_set_bit(0, 17);
 334                 restore_vx_regs(vxrs);
 335         }
 336         preempt_enable();
 337         return 0;
 338 }
 339
 340 void vector_exception(struct pt_regs *regs)
 341 {
 342         int si_code, vic;
 343
 344         if (!MACHINE_HAS_VX) {
 345                 do_trap(regs, SIGILL, ILL_ILLOPN, "illegal operation");
 346                 return;
 347         }
 348
 349         /* get vector interrupt code from fpc */
 350         asm volatile("stfpc %0" : "=m" (current->thread.fp_regs.fpc));
 351         vic = (current->thread.fp_regs.fpc & 0xf00) >> 8;
 352         switch (vic) {
 353         case 1: /* invalid vector operation */
 354                 si_code = FPE_FLTINV;
 355                 break;
 356         case 2: /* division by zero */
 357                 si_code = FPE_FLTDIV;
 358                 break;
 359         case 3: /* overflow */
 360                 si_code = FPE_FLTOVF;
 361                 break;
 362         case 4: /* underflow */
 363                 si_code = FPE_FLTUND;
 364                 break;
 365         case 5: /* inexact */
 366                 si_code = FPE_FLTRES;
 367                 break;
 368         default: /* unknown cause */
 369                 si_code = 0;
 370         }
 371         do_trap(regs, SIGFPE, si_code, "vector exception");
 372 }
 373
 374 static int __init disable_vector_extension(char *str)
 375 {
 376         S390_lowcore.machine_flags &= ~MACHINE_FLAG_VX;
 377         return 1;
 378 }
 379 __setup("novx", disable_vector_extension);
 380 #endif
 381
 382 void data_exception(struct pt_regs *regs)
 383 {
 384         __u16 __user *location;
 385         int signal = 0;
 386
 387         location = get_trap_ip(regs);
 388
 389         if (MACHINE_HAS_IEEE)
 390                 asm volatile("stfpc %0" : "=m" (current->thread.fp_regs.fpc));
 391
 392 #ifdef CONFIG_MATHEMU
 393         else if (user_mode(regs)) {
 394                 __u8 opcode[6];
 395                 get_user(*((__u16 *) opcode), location);
 396                 switch (opcode[0]) {
 397                 case 0x28: /* LDR Rx,Ry   */
 398                         signal = math_emu_ldr(opcode);
 399                         break;
 400                 case 0x38: /* LER Rx,Ry   */
 401                         signal = math_emu_ler(opcode);
 402                         break;
 403                 case 0x60: /* STD R,D(X,B) */
 404                         get_user(*((__u16 *) (opcode+2)), location+1);
 405                         signal = math_emu_std(opcode, regs);
 406                         break;
 407                 case 0x68: /* LD R,D(X,B) */
 408                         get_user(*((__u16 *) (opcode+2)), location+1);
 409                         signal = math_emu_ld(opcode, regs);
 410                         break;
 411                 case 0x70: /* STE R,D(X,B) */
 412                         get_user(*((__u16 *) (opcode+2)), location+1);
 413                         signal = math_emu_ste(opcode, regs);
 414                         break;
 415                 case 0x78: /* LE R,D(X,B) */
 416                         get_user(*((__u16 *) (opcode+2)), location+1);
 417                         signal = math_emu_le(opcode, regs);
 418                         break;
 419                 case 0xb3:
 420                         get_user(*((__u16 *) (opcode+2)), location+1);
 421                         signal = math_emu_b3(opcode, regs);
 422                         break;
 423                 case 0xed:
 424                         get_user(*((__u32 *) (opcode+2)),
 425                                  (__u32 __user *)(location+1));
 426                         signal = math_emu_ed(opcode, regs);
 427                         break;
 428                 case 0xb2:
 429                         if (opcode[1] == 0x99) {
 430                                 get_user(*((__u16 *) (opcode+2)), location+1);
 431                                 signal = math_emu_srnm(opcode, regs);
 432                         } else if (opcode[1] == 0x9c) {
 433                                 get_user(*((__u16 *) (opcode+2)), location+1);
 434                                 signal = math_emu_stfpc(opcode, regs);
 435                         } else if (opcode[1] == 0x9d) {
 436                                 get_user(*((__u16 *) (opcode+2)), location+1);
 437                                 signal = math_emu_lfpc(opcode, regs);
 438                         } else
 439                                 signal = SIGILL;
 440                         break;
 441                 default:
 442                         signal = SIGILL;
 443                         break;
 444                 }
 445         }
 446 #endif
 447 #ifdef CONFIG_64BIT
 448         /* Check for vector register enablement */
 449         if (MACHINE_HAS_VX && !current->thread.vxrs &&
 450             (current->thread.fp_regs.fpc & FPC_DXC_MASK) == 0xfe00) {
 451                 alloc_vector_registers(current);
 452                 /* Vector data exception is suppressing, rewind psw. */
 453                 regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16);
 454                 clear_pt_regs_flag(regs, PIF_PER_TRAP);
 455                 return;
 456         }
 457 #endif
 458
 459         if (current->thread.fp_regs.fpc & FPC_DXC_MASK)
 460                 signal = SIGFPE;
 461         else
 462                 signal = SIGILL;
 463         if (signal == SIGFPE)
 464                 do_fp_trap(regs, current->thread.fp_regs.fpc);
 465         else if (signal)
 466                 do_trap(regs, signal, ILL_ILLOPN, "data exception");
 467 }
 468
 469 void space_switch_exception(struct pt_regs *regs)
 470 {
 471         /* Set user psw back to home space mode. */
 472         if (user_mode(regs))
 473                 regs->psw.mask |= PSW_ASC_HOME;
 474         /* Send SIGILL. */
 475         do_trap(regs, SIGILL, ILL_PRVOPC, "space switch event");
 476 }
 477
 478 void kernel_stack_overflow(struct pt_regs *regs)
 479 {
 480         bust_spinlocks(1);
 481         printk("Kernel stack overflow.\n");
 482         show_regs(regs);
 483         bust_spinlocks(0);
 484         panic("Corrupt kernel stack, can't continue.");
 485 }
 486 NOKPROBE_SYMBOL(kernel_stack_overflow);
 487
 488 void __init trap_init(void)
 489 {
 490         local_mcck_enable();
 491 }