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