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 do_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
  91 {
  92         if (notify_die(DIE_TRAP, str, regs, 0,
  93                        regs->int_code, si_signo) == NOTIFY_STOP)
  94                 return;
  95         do_report_trap(regs, si_signo, si_code, str);
  96 }
  97 NOKPROBE_SYMBOL(do_trap);
  98
  99 void 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 NOKPROBE_SYMBOL(do_per_trap);
 115
 116 void default_trap_handler(struct pt_regs *regs)
 117 {
 118         if (user_mode(regs)) {
 119                 report_user_fault(regs, SIGSEGV);
 120                 do_exit(SIGSEGV);
 121         } else
 122                 die(regs, "Unknown program exception");
 123 }
 124
 125 #define DO_ERROR_INFO(name, signr, sicode, str) \
 126 void name(struct pt_regs *regs)                 \
 127 {                                               \
 128         do_trap(regs, signr, sicode, str);      \
 129 }
 130
 131 DO_ERROR_INFO(addressing_exception, SIGILL, ILL_ILLADR,
 132               "addressing exception")
 133 DO_ERROR_INFO(execute_exception, SIGILL, ILL_ILLOPN,
 134               "execute exception")
 135 DO_ERROR_INFO(divide_exception, SIGFPE, FPE_INTDIV,
 136               "fixpoint divide exception")
 137 DO_ERROR_INFO(overflow_exception, SIGFPE, FPE_INTOVF,
 138               "fixpoint overflow exception")
 139 DO_ERROR_INFO(hfp_overflow_exception, SIGFPE, FPE_FLTOVF,
 140               "HFP overflow exception")
 141 DO_ERROR_INFO(hfp_underflow_exception, SIGFPE, FPE_FLTUND,
 142               "HFP underflow exception")
 143 DO_ERROR_INFO(hfp_significance_exception, SIGFPE, FPE_FLTRES,
 144               "HFP significance exception")
 145 DO_ERROR_INFO(hfp_divide_exception, SIGFPE, FPE_FLTDIV,
 146               "HFP divide exception")
 147 DO_ERROR_INFO(hfp_sqrt_exception, SIGFPE, FPE_FLTINV,
 148               "HFP square root exception")
 149 DO_ERROR_INFO(operand_exception, SIGILL, ILL_ILLOPN,
 150               "operand exception")
 151 DO_ERROR_INFO(privileged_op, SIGILL, ILL_PRVOPC,
 152               "privileged operation")
 153 DO_ERROR_INFO(special_op_exception, SIGILL, ILL_ILLOPN,
 154               "special operation exception")
 155 DO_ERROR_INFO(translation_exception, SIGILL, ILL_ILLOPN,
 156               "translation exception")
 157
 158 #ifdef CONFIG_64BIT
 159 DO_ERROR_INFO(transaction_exception, SIGILL, ILL_ILLOPN,
 160               "transaction constraint exception")
 161 #endif
 162
 163 static inline void do_fp_trap(struct pt_regs *regs, int fpc)
 164 {
 165         int si_code = 0;
 166         /* FPC[2] is Data Exception Code */
 167         if ((fpc & 0x00000300) == 0) {
 168                 /* bits 6 and 7 of DXC are 0 iff IEEE exception */
 169                 if (fpc & 0x8000) /* invalid fp operation */
 170                         si_code = FPE_FLTINV;
 171                 else if (fpc & 0x4000) /* div by 0 */
 172                         si_code = FPE_FLTDIV;
 173                 else if (fpc & 0x2000) /* overflow */
 174                         si_code = FPE_FLTOVF;
 175                 else if (fpc & 0x1000) /* underflow */
 176                         si_code = FPE_FLTUND;
 177                 else if (fpc & 0x0800) /* inexact */
 178                         si_code = FPE_FLTRES;
 179         }
 180         do_trap(regs, SIGFPE, si_code, "floating point exception");
 181 }
 182
 183 void illegal_op(struct pt_regs *regs)
 184 {
 185         siginfo_t info;
 186         __u8 opcode[6];
 187         __u16 __user *location;
 188         int is_uprobe_insn = 0;
 189         int signal = 0;
 190
 191         location = get_trap_ip(regs);
 192
 193         if (user_mode(regs)) {
 194                 if (get_user(*((__u16 *) opcode), (__u16 __user *) location))
 195                         return;
 196                 if (*((__u16 *) opcode) == S390_BREAKPOINT_U16) {
 197                         if (current->ptrace) {
 198                                 info.si_signo = SIGTRAP;
 199                                 info.si_errno = 0;
 200                                 info.si_code = TRAP_BRKPT;
 201                                 info.si_addr = location;
 202                                 force_sig_info(SIGTRAP, &info, current);
 203                         } else
 204                                 signal = SIGILL;
 205 #ifdef CONFIG_UPROBES
 206                 } else if (*((__u16 *) opcode) == UPROBE_SWBP_INSN) {
 207                         is_uprobe_insn = 1;
 208 #endif
 209 #ifdef CONFIG_MATHEMU
 210                 } else if (opcode[0] == 0xb3) {
 211                         if (get_user(*((__u16 *) (opcode+2)), location+1))
 212                                 return;
 213                         signal = math_emu_b3(opcode, regs);
 214                 } else if (opcode[0] == 0xed) {
 215                         if (get_user(*((__u32 *) (opcode+2)),
 216                                      (__u32 __user *)(location+1)))
 217                                 return;
 218                         signal = math_emu_ed(opcode, regs);
 219                 } else if (*((__u16 *) opcode) == 0xb299) {
 220                         if (get_user(*((__u16 *) (opcode+2)), location+1))
 221                                 return;
 222                         signal = math_emu_srnm(opcode, regs);
 223                 } else if (*((__u16 *) opcode) == 0xb29c) {
 224                         if (get_user(*((__u16 *) (opcode+2)), location+1))
 225                                 return;
 226                         signal = math_emu_stfpc(opcode, regs);
 227                 } else if (*((__u16 *) opcode) == 0xb29d) {
 228                         if (get_user(*((__u16 *) (opcode+2)), location+1))
 229                                 return;
 230                         signal = math_emu_lfpc(opcode, regs);
 231 #endif
 232                 } else
 233                         signal = SIGILL;
 234         }
 235         /*
 236          * We got either an illegal op in kernel mode, or user space trapped
 237          * on a uprobes illegal instruction. See if kprobes or uprobes picks
 238          * it up. If not, SIGILL.
 239          */
 240         if (is_uprobe_insn || !user_mode(regs)) {
 241                 if (notify_die(DIE_BPT, "bpt", regs, 0,
 242                                3, SIGTRAP) != NOTIFY_STOP)
 243                         signal = SIGILL;
 244         }
 245
 246 #ifdef CONFIG_MATHEMU
 247         if (signal == SIGFPE)
 248                 do_fp_trap(regs, current->thread.fp_regs.fpc);
 249         else if (signal == SIGSEGV)
 250                 do_trap(regs, signal, SEGV_MAPERR, "user address fault");
 251         else
 252 #endif
 253         if (signal)
 254                 do_trap(regs, signal, ILL_ILLOPC, "illegal operation");
 255 }
 256 NOKPROBE_SYMBOL(illegal_op);
 257
 258 #ifdef CONFIG_MATHEMU
 259 void specification_exception(struct pt_regs *regs)
 260 {
 261         __u8 opcode[6];
 262         __u16 __user *location = NULL;
 263         int signal = 0;
 264
 265         location = (__u16 __user *) get_trap_ip(regs);
 266
 267         if (user_mode(regs)) {
 268                 get_user(*((__u16 *) opcode), location);
 269                 switch (opcode[0]) {
 270                 case 0x28: /* LDR Rx,Ry   */
 271                         signal = math_emu_ldr(opcode);
 272                         break;
 273                 case 0x38: /* LER Rx,Ry   */
 274                         signal = math_emu_ler(opcode);
 275                         break;
 276                 case 0x60: /* STD R,D(X,B) */
 277                         get_user(*((__u16 *) (opcode+2)), location+1);
 278                         signal = math_emu_std(opcode, regs);
 279                         break;
 280                 case 0x68: /* LD R,D(X,B) */
 281                         get_user(*((__u16 *) (opcode+2)), location+1);
 282                         signal = math_emu_ld(opcode, regs);
 283                         break;
 284                 case 0x70: /* STE R,D(X,B) */
 285                         get_user(*((__u16 *) (opcode+2)), location+1);
 286                         signal = math_emu_ste(opcode, regs);
 287                         break;
 288                 case 0x78: /* LE R,D(X,B) */
 289                         get_user(*((__u16 *) (opcode+2)), location+1);
 290                         signal = math_emu_le(opcode, regs);
 291                         break;
 292                 default:
 293                         signal = SIGILL;
 294                         break;
 295                 }
 296         } else
 297                 signal = SIGILL;
 298
 299         if (signal == SIGFPE)
 300                 do_fp_trap(regs, current->thread.fp_regs.fpc);
 301         else if (signal)
 302                 do_trap(regs, signal, ILL_ILLOPN, "specification exception");
 303 }
 304 #else
 305 DO_ERROR_INFO(specification_exception, SIGILL, ILL_ILLOPN,
 306               "specification exception");
 307 #endif
 308
 309 #ifdef CONFIG_64BIT
 310 int alloc_vector_registers(struct task_struct *tsk)
 311 {
 312         __vector128 *vxrs;
 313         int i;
 314
 315         /* Allocate vector register save area. */
 316         vxrs = kzalloc(sizeof(__vector128) * __NUM_VXRS,
 317                        GFP_KERNEL|__GFP_REPEAT);
 318         if (!vxrs)
 319                 return -ENOMEM;
 320         preempt_disable();
 321         if (tsk == current)
 322                 save_fp_regs(tsk->thread.fp_regs.fprs);
 323         /* Copy the 16 floating point registers */
 324         for (i = 0; i < 16; i++)
 325                 *(freg_t *) &vxrs[i] = tsk->thread.fp_regs.fprs[i];
 326         tsk->thread.vxrs = vxrs;
 327         if (tsk == current) {
 328                 __ctl_set_bit(0, 17);
 329                 restore_vx_regs(vxrs);
 330         }
 331         preempt_enable();
 332         return 0;
 333 }
 334
 335 void vector_exception(struct pt_regs *regs)
 336 {
 337         int si_code, vic;
 338
 339         if (!MACHINE_HAS_VX) {
 340                 do_trap(regs, SIGILL, ILL_ILLOPN, "illegal operation");
 341                 return;
 342         }
 343
 344         /* get vector interrupt code from fpc */
 345         asm volatile("stfpc %0" : "=m" (current->thread.fp_regs.fpc));
 346         vic = (current->thread.fp_regs.fpc & 0xf00) >> 8;
 347         switch (vic) {
 348         case 1: /* invalid vector operation */
 349                 si_code = FPE_FLTINV;
 350                 break;
 351         case 2: /* division by zero */
 352                 si_code = FPE_FLTDIV;
 353                 break;
 354         case 3: /* overflow */
 355                 si_code = FPE_FLTOVF;
 356                 break;
 357         case 4: /* underflow */
 358                 si_code = FPE_FLTUND;
 359                 break;
 360         case 5: /* inexact */
 361                 si_code = FPE_FLTRES;
 362                 break;
 363         default: /* unknown cause */
 364                 si_code = 0;
 365         }
 366         do_trap(regs, SIGFPE, si_code, "vector exception");
 367 }
 368
 369 static int __init disable_vector_extension(char *str)
 370 {
 371         S390_lowcore.machine_flags &= ~MACHINE_FLAG_VX;
 372         return 1;
 373 }
 374 __setup("novx", disable_vector_extension);
 375 #endif
 376
 377 void data_exception(struct pt_regs *regs)
 378 {
 379         __u16 __user *location;
 380         int signal = 0;
 381
 382         location = get_trap_ip(regs);
 383
 384         if (MACHINE_HAS_IEEE)
 385                 asm volatile("stfpc %0" : "=m" (current->thread.fp_regs.fpc));
 386
 387 #ifdef CONFIG_MATHEMU
 388         else if (user_mode(regs)) {
 389                 __u8 opcode[6];
 390                 get_user(*((__u16 *) opcode), location);
 391                 switch (opcode[0]) {
 392                 case 0x28: /* LDR Rx,Ry   */
 393                         signal = math_emu_ldr(opcode);
 394                         break;
 395                 case 0x38: /* LER Rx,Ry   */
 396                         signal = math_emu_ler(opcode);
 397                         break;
 398                 case 0x60: /* STD R,D(X,B) */
 399                         get_user(*((__u16 *) (opcode+2)), location+1);
 400                         signal = math_emu_std(opcode, regs);
 401                         break;
 402                 case 0x68: /* LD R,D(X,B) */
 403                         get_user(*((__u16 *) (opcode+2)), location+1);
 404                         signal = math_emu_ld(opcode, regs);
 405                         break;
 406                 case 0x70: /* STE R,D(X,B) */
 407                         get_user(*((__u16 *) (opcode+2)), location+1);
 408                         signal = math_emu_ste(opcode, regs);
 409                         break;
 410                 case 0x78: /* LE R,D(X,B) */
 411                         get_user(*((__u16 *) (opcode+2)), location+1);
 412                         signal = math_emu_le(opcode, regs);
 413                         break;
 414                 case 0xb3:
 415                         get_user(*((__u16 *) (opcode+2)), location+1);
 416                         signal = math_emu_b3(opcode, regs);
 417                         break;
 418                 case 0xed:
 419                         get_user(*((__u32 *) (opcode+2)),
 420                                  (__u32 __user *)(location+1));
 421                         signal = math_emu_ed(opcode, regs);
 422                         break;
 423                 case 0xb2:
 424                         if (opcode[1] == 0x99) {
 425                                 get_user(*((__u16 *) (opcode+2)), location+1);
 426                                 signal = math_emu_srnm(opcode, regs);
 427                         } else if (opcode[1] == 0x9c) {
 428                                 get_user(*((__u16 *) (opcode+2)), location+1);
 429                                 signal = math_emu_stfpc(opcode, regs);
 430                         } else if (opcode[1] == 0x9d) {
 431                                 get_user(*((__u16 *) (opcode+2)), location+1);
 432                                 signal = math_emu_lfpc(opcode, regs);
 433                         } else
 434                                 signal = SIGILL;
 435                         break;
 436                 default:
 437                         signal = SIGILL;
 438                         break;
 439                 }
 440         }
 441 #endif
 442 #ifdef CONFIG_64BIT
 443         /* Check for vector register enablement */
 444         if (MACHINE_HAS_VX && !current->thread.vxrs &&
 445             (current->thread.fp_regs.fpc & FPC_DXC_MASK) == 0xfe00) {
 446                 alloc_vector_registers(current);
 447                 /* Vector data exception is suppressing, rewind psw. */
 448                 regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16);
 449                 clear_pt_regs_flag(regs, PIF_PER_TRAP);
 450                 return;
 451         }
 452 #endif
 453
 454         if (current->thread.fp_regs.fpc & FPC_DXC_MASK)
 455                 signal = SIGFPE;
 456         else
 457                 signal = SIGILL;
 458         if (signal == SIGFPE)
 459                 do_fp_trap(regs, current->thread.fp_regs.fpc);
 460         else if (signal)
 461                 do_trap(regs, signal, ILL_ILLOPN, "data exception");
 462 }
 463
 464 void space_switch_exception(struct pt_regs *regs)
 465 {
 466         /* Set user psw back to home space mode. */
 467         if (user_mode(regs))
 468                 regs->psw.mask |= PSW_ASC_HOME;
 469         /* Send SIGILL. */
 470         do_trap(regs, SIGILL, ILL_PRVOPC, "space switch event");
 471 }
 472
 473 void kernel_stack_overflow(struct pt_regs *regs)
 474 {
 475         bust_spinlocks(1);
 476         printk("Kernel stack overflow.\n");
 477         show_regs(regs);
 478         bust_spinlocks(0);
 479         panic("Corrupt kernel stack, can't continue.");
 480 }
 481 NOKPROBE_SYMBOL(kernel_stack_overflow);
 482
 483 void __init trap_init(void)
 484 {
 485         local_mcck_enable();
 486 }