arch/ppc64/kernel/traps.c

   1 /*
   2  *  linux/arch/ppc64/kernel/traps.c
   3  *
   4  *  Copyright (C) 1995-1996  Gary Thomas (gdt@linuxppc.org)
   5  *
   6  *  This program is free software; you can redistribute it and/or
   7  *  modify it under the terms of the GNU General Public License
   8  *  as published by the Free Software Foundation; either version
   9  *  2 of the License, or (at your option) any later version.
  10  *
  11  *  Modified by Cort Dougan (cort@cs.nmt.edu)
  12  *  and Paul Mackerras (paulus@cs.anu.edu.au)
  13  */
  14
  15 /*
  16  * This file handles the architecture-dependent parts of hardware exceptions
  17  */
  18
  19 #include <linux/config.h>
  20 #include <linux/errno.h>
  21 #include <linux/sched.h>
  22 #include <linux/kernel.h>
  23 #include <linux/mm.h>
  24 #include <linux/stddef.h>
  25 #include <linux/unistd.h>
  26 #include <linux/slab.h>
  27 #include <linux/user.h>
  28 #include <linux/a.out.h>
  29 #include <linux/interrupt.h>
  30 #include <linux/init.h>
  31 #include <linux/module.h>
  32 #include <linux/delay.h>
  33 #include <asm/kdebug.h>
  34
  35 #include <asm/pgtable.h>
  36 #include <asm/uaccess.h>
  37 #include <asm/system.h>
  38 #include <asm/io.h>
  39 #include <asm/processor.h>
  40 #include <asm/ppcdebug.h>
  41 #include <asm/rtas.h>
  42 #include <asm/systemcfg.h>
  43 #include <asm/machdep.h>
  44 #include <asm/pmc.h>
  45
  46 #ifdef CONFIG_DEBUGGER
  47 int (*__debugger)(struct pt_regs *regs);
  48 int (*__debugger_ipi)(struct pt_regs *regs);
  49 int (*__debugger_bpt)(struct pt_regs *regs);
  50 int (*__debugger_sstep)(struct pt_regs *regs);
  51 int (*__debugger_iabr_match)(struct pt_regs *regs);
  52 int (*__debugger_dabr_match)(struct pt_regs *regs);
  53 int (*__debugger_fault_handler)(struct pt_regs *regs);
  54
  55 EXPORT_SYMBOL(__debugger);
  56 EXPORT_SYMBOL(__debugger_ipi);
  57 EXPORT_SYMBOL(__debugger_bpt);
  58 EXPORT_SYMBOL(__debugger_sstep);
  59 EXPORT_SYMBOL(__debugger_iabr_match);
  60 EXPORT_SYMBOL(__debugger_dabr_match);
  61 EXPORT_SYMBOL(__debugger_fault_handler);
  62 #endif
  63
  64 struct notifier_block *ppc64_die_chain;
  65 static DEFINE_SPINLOCK(die_notifier_lock);
  66
  67 int register_die_notifier(struct notifier_block *nb)
  68 {
  69         int err = 0;
  70         unsigned long flags;
  71
  72         spin_lock_irqsave(&die_notifier_lock, flags);
  73         err = notifier_chain_register(&ppc64_die_chain, nb);
  74         spin_unlock_irqrestore(&die_notifier_lock, flags);
  75         return err;
  76 }
  77
  78 /*
  79  * Trap & Exception support
  80  */
  81
  82 static DEFINE_SPINLOCK(die_lock);
  83
  84 int die(const char *str, struct pt_regs *regs, long err)
  85 {
  86         static int die_counter;
  87         int nl = 0;
  88
  89         if (debugger(regs))
  90                 return 1;
  91
  92         console_verbose();
  93         spin_lock_irq(&die_lock);
  94         bust_spinlocks(1);
  95         printk("Oops: %s, sig: %ld [#%d]\n", str, err, ++die_counter);
  96 #ifdef CONFIG_PREEMPT
  97         printk("PREEMPT ");
  98         nl = 1;
  99 #endif
 100 #ifdef CONFIG_SMP
 101         printk("SMP NR_CPUS=%d ", NR_CPUS);
 102         nl = 1;
 103 #endif
 104 #ifdef CONFIG_DEBUG_PAGEALLOC
 105         printk("DEBUG_PAGEALLOC ");
 106         nl = 1;
 107 #endif
 108 #ifdef CONFIG_NUMA
 109         printk("NUMA ");
 110         nl = 1;
 111 #endif
 112         switch(systemcfg->platform) {
 113                 case PLATFORM_PSERIES:
 114                         printk("PSERIES ");
 115                         nl = 1;
 116                         break;
 117                 case PLATFORM_PSERIES_LPAR:
 118                         printk("PSERIES LPAR ");
 119                         nl = 1;
 120                         break;
 121                 case PLATFORM_ISERIES_LPAR:
 122                         printk("ISERIES LPAR ");
 123                         nl = 1;
 124                         break;
 125                 case PLATFORM_POWERMAC:
 126                         printk("POWERMAC ");
 127                         nl = 1;
 128                         break;
 129         }
 130         if (nl)
 131                 printk("\n");
 132         print_modules();
 133         show_regs(regs);
 134         bust_spinlocks(0);
 135         spin_unlock_irq(&die_lock);
 136
 137         if (in_interrupt())
 138                 panic("Fatal exception in interrupt");
 139
 140         if (panic_on_oops) {
 141                 printk(KERN_EMERG "Fatal exception: panic in 5 seconds\n");
 142                 ssleep(5);
 143                 panic("Fatal exception");
 144         }
 145         do_exit(SIGSEGV);
 146
 147         return 0;
 148 }
 149
 150 void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr)
 151 {
 152         siginfo_t info;
 153
 154         if (!user_mode(regs)) {
 155                 if (die("Exception in kernel mode", regs, signr))
 156                         return;
 157         }
 158
 159         memset(&info, 0, sizeof(info));
 160         info.si_signo = signr;
 161         info.si_code = code;
 162         info.si_addr = (void __user *) addr;
 163         force_sig_info(signr, &info, current);
 164 }
 165
 166 void system_reset_exception(struct pt_regs *regs)
 167 {
 168         /* See if any machine dependent calls */
 169         if (ppc_md.system_reset_exception)
 170                 ppc_md.system_reset_exception(regs);
 171
 172         die("System Reset", regs, 0);
 173
 174         /* Must die if the interrupt is not recoverable */
 175         if (!(regs->msr & MSR_RI))
 176                 panic("Unrecoverable System Reset");
 177
 178         /* What should we do here? We could issue a shutdown or hard reset. */
 179 }
 180
 181 void machine_check_exception(struct pt_regs *regs)
 182 {
 183         int recover = 0;
 184
 185         /* See if any machine dependent calls */
 186         if (ppc_md.machine_check_exception)
 187                 recover = ppc_md.machine_check_exception(regs);
 188
 189         if (recover)
 190                 return;
 191
 192         if (debugger_fault_handler(regs))
 193                 return;
 194         die("Machine check", regs, 0);
 195
 196         /* Must die if the interrupt is not recoverable */
 197         if (!(regs->msr & MSR_RI))
 198                 panic("Unrecoverable Machine check");
 199 }
 200
 201 void unknown_exception(struct pt_regs *regs)
 202 {
 203         printk("Bad trap at PC: %lx, SR: %lx, vector=%lx\n",
 204                regs->nip, regs->msr, regs->trap);
 205
 206         _exception(SIGTRAP, regs, 0, 0);
 207 }
 208
 209 void instruction_breakpoint_exception(struct pt_regs *regs)
 210 {
 211         if (notify_die(DIE_IABR_MATCH, "iabr_match", regs, 5,
 212                                         5, SIGTRAP) == NOTIFY_STOP)
 213                 return;
 214         if (debugger_iabr_match(regs))
 215                 return;
 216         _exception(SIGTRAP, regs, TRAP_BRKPT, regs->nip);
 217 }
 218
 219 void single_step_exception(struct pt_regs *regs)
 220 {
 221         regs->msr &= ~MSR_SE;  /* Turn off 'trace' bit */
 222
 223         if (notify_die(DIE_SSTEP, "single_step", regs, 5,
 224                                         5, SIGTRAP) == NOTIFY_STOP)
 225                 return;
 226         if (debugger_sstep(regs))
 227                 return;
 228
 229         _exception(SIGTRAP, regs, TRAP_TRACE, regs->nip);
 230 }
 231
 232 /*
 233  * After we have successfully emulated an instruction, we have to
 234  * check if the instruction was being single-stepped, and if so,
 235  * pretend we got a single-step exception.  This was pointed out
 236  * by Kumar Gala.  -- paulus
 237  */
 238 static inline void emulate_single_step(struct pt_regs *regs)
 239 {
 240         if (regs->msr & MSR_SE)
 241                 single_step_exception(regs);
 242 }
 243
 244 static void parse_fpe(struct pt_regs *regs)
 245 {
 246         int code = 0;
 247         unsigned long fpscr;
 248
 249         flush_fp_to_thread(current);
 250
 251         fpscr = current->thread.fpscr;
 252
 253         /* Invalid operation */
 254         if ((fpscr & FPSCR_VE) && (fpscr & FPSCR_VX))
 255                 code = FPE_FLTINV;
 256
 257         /* Overflow */
 258         else if ((fpscr & FPSCR_OE) && (fpscr & FPSCR_OX))
 259                 code = FPE_FLTOVF;
 260
 261         /* Underflow */
 262         else if ((fpscr & FPSCR_UE) && (fpscr & FPSCR_UX))
 263                 code = FPE_FLTUND;
 264
 265         /* Divide by zero */
 266         else if ((fpscr & FPSCR_ZE) && (fpscr & FPSCR_ZX))
 267                 code = FPE_FLTDIV;
 268
 269         /* Inexact result */
 270         else if ((fpscr & FPSCR_XE) && (fpscr & FPSCR_XX))
 271                 code = FPE_FLTRES;
 272
 273         _exception(SIGFPE, regs, code, regs->nip);
 274 }
 275
 276 /*
 277  * Illegal instruction emulation support.  Return non-zero if we can't
 278  * emulate, or -EFAULT if the associated memory access caused an access
 279  * fault.  Return zero on success.
 280  */
 281
 282 #define INST_MFSPR_PVR          0x7c1f42a6
 283 #define INST_MFSPR_PVR_MASK     0xfc1fffff
 284
 285 #define INST_DCBA               0x7c0005ec
 286 #define INST_DCBA_MASK          0x7c0007fe
 287
 288 #define INST_MCRXR              0x7c000400
 289 #define INST_MCRXR_MASK         0x7c0007fe
 290
 291 static int emulate_instruction(struct pt_regs *regs)
 292 {
 293         unsigned int instword;
 294
 295         if (!user_mode(regs))
 296                 return -EINVAL;
 297
 298         CHECK_FULL_REGS(regs);
 299
 300         if (get_user(instword, (unsigned int __user *)(regs->nip)))
 301                 return -EFAULT;
 302
 303         /* Emulate the mfspr rD, PVR. */
 304         if ((instword & INST_MFSPR_PVR_MASK) == INST_MFSPR_PVR) {
 305                 unsigned int rd;
 306
 307                 rd = (instword >> 21) & 0x1f;
 308                 regs->gpr[rd] = mfspr(SPRN_PVR);
 309                 return 0;
 310         }
 311
 312         /* Emulating the dcba insn is just a no-op.  */
 313         if ((instword & INST_DCBA_MASK) == INST_DCBA) {
 314                 static int warned;
 315
 316                 if (!warned) {
 317                         printk(KERN_WARNING
 318                                "process %d (%s) uses obsolete 'dcba' insn\n",
 319                                current->pid, current->comm);
 320                         warned = 1;
 321                 }
 322                 return 0;
 323         }
 324
 325         /* Emulate the mcrxr insn.  */
 326         if ((instword & INST_MCRXR_MASK) == INST_MCRXR) {
 327                 static int warned;
 328                 unsigned int shift;
 329
 330                 if (!warned) {
 331                         printk(KERN_WARNING
 332                                "process %d (%s) uses obsolete 'mcrxr' insn\n",
 333                                current->pid, current->comm);
 334                         warned = 1;
 335                 }
 336
 337                 shift = (instword >> 21) & 0x1c;
 338                 regs->ccr &= ~(0xf0000000 >> shift);
 339                 regs->ccr |= (regs->xer & 0xf0000000) >> shift;
 340                 regs->xer &= ~0xf0000000;
 341                 return 0;
 342         }
 343
 344         return -EINVAL;
 345 }
 346
 347 /*
 348  * Look through the list of trap instructions that are used for BUG(),
 349  * BUG_ON() and WARN_ON() and see if we hit one.  At this point we know
 350  * that the exception was caused by a trap instruction of some kind.
 351  * Returns 1 if we should continue (i.e. it was a WARN_ON) or 0
 352  * otherwise.
 353  */
 354 extern struct bug_entry __start___bug_table[], __stop___bug_table[];
 355
 356 #ifndef CONFIG_MODULES
 357 #define module_find_bug(x)      NULL
 358 #endif
 359
 360 struct bug_entry *find_bug(unsigned long bugaddr)
 361 {
 362         struct bug_entry *bug;
 363
 364         for (bug = __start___bug_table; bug < __stop___bug_table; ++bug)
 365                 if (bugaddr == bug->bug_addr)
 366                         return bug;
 367         return module_find_bug(bugaddr);
 368 }
 369
 370 static int
 371 check_bug_trap(struct pt_regs *regs)
 372 {
 373         struct bug_entry *bug;
 374         unsigned long addr;
 375
 376         if (regs->msr & MSR_PR)
 377                 return 0;       /* not in kernel */
 378         addr = regs->nip;       /* address of trap instruction */
 379         if (addr < PAGE_OFFSET)
 380                 return 0;
 381         bug = find_bug(regs->nip);
 382         if (bug == NULL)
 383                 return 0;
 384         if (bug->line & BUG_WARNING_TRAP) {
 385                 /* this is a WARN_ON rather than BUG/BUG_ON */
 386                 printk(KERN_ERR "Badness in %s at %s:%d\n",
 387                        bug->function, bug->file,
 388                       (unsigned int)bug->line & ~BUG_WARNING_TRAP);
 389                 show_stack(current, (void *)regs->gpr[1]);
 390                 return 1;
 391         }
 392         printk(KERN_CRIT "kernel BUG in %s at %s:%d!\n",
 393                bug->function, bug->file, (unsigned int)bug->line);
 394         return 0;
 395 }
 396
 397 void program_check_exception(struct pt_regs *regs)
 398 {
 399         if (debugger_fault_handler(regs))
 400                 return;
 401
 402         if (regs->msr & 0x100000) {
 403                 /* IEEE FP exception */
 404                 parse_fpe(regs);
 405         } else if (regs->msr & 0x20000) {
 406                 /* trap exception */
 407
 408                 if (notify_die(DIE_BPT, "breakpoint", regs, 5,
 409                                         5, SIGTRAP) == NOTIFY_STOP)
 410                         return;
 411                 if (debugger_bpt(regs))
 412                         return;
 413
 414                 if (check_bug_trap(regs)) {
 415                         regs->nip += 4;
 416                         return;
 417                 }
 418                 _exception(SIGTRAP, regs, TRAP_BRKPT, regs->nip);
 419
 420         } else {
 421                 /* Privileged or illegal instruction; try to emulate it. */
 422                 switch (emulate_instruction(regs)) {
 423                 case 0:
 424                         regs->nip += 4;
 425                         emulate_single_step(regs);
 426                         break;
 427
 428                 case -EFAULT:
 429                         _exception(SIGSEGV, regs, SEGV_MAPERR, regs->nip);
 430                         break;
 431
 432                 default:
 433                         if (regs->msr & 0x40000)
 434                                 /* priveleged */
 435                                 _exception(SIGILL, regs, ILL_PRVOPC, regs->nip);
 436                         else
 437                                 /* illegal */
 438                                 _exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
 439                         break;
 440                 }
 441         }
 442 }
 443
 444 void kernel_fp_unavailable_exception(struct pt_regs *regs)
 445 {
 446         printk(KERN_EMERG "Unrecoverable FP Unavailable Exception "
 447                           "%lx at %lx\n", regs->trap, regs->nip);
 448         die("Unrecoverable FP Unavailable Exception", regs, SIGABRT);
 449 }
 450
 451 void altivec_unavailable_exception(struct pt_regs *regs)
 452 {
 453         if (user_mode(regs)) {
 454                 /* A user program has executed an altivec instruction,
 455                    but this kernel doesn't support altivec. */
 456                 _exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
 457                 return;
 458         }
 459         printk(KERN_EMERG "Unrecoverable VMX/Altivec Unavailable Exception "
 460                           "%lx at %lx\n", regs->trap, regs->nip);
 461         die("Unrecoverable VMX/Altivec Unavailable Exception", regs, SIGABRT);
 462 }
 463
 464 extern perf_irq_t perf_irq;
 465
 466 void performance_monitor_exception(struct pt_regs *regs)
 467 {
 468         perf_irq(regs);
 469 }
 470
 471 void alignment_exception(struct pt_regs *regs)
 472 {
 473         int fixed;
 474
 475         fixed = fix_alignment(regs);
 476
 477         if (fixed == 1) {
 478                 regs->nip += 4; /* skip over emulated instruction */
 479                 emulate_single_step(regs);
 480                 return;
 481         }
 482
 483         /* Operand address was bad */
 484         if (fixed == -EFAULT) {
 485                 if (user_mode(regs)) {
 486                         _exception(SIGSEGV, regs, SEGV_MAPERR, regs->dar);
 487                 } else {
 488                         /* Search exception table */
 489                         bad_page_fault(regs, regs->dar, SIGSEGV);
 490                 }
 491
 492                 return;
 493         }
 494
 495         _exception(SIGBUS, regs, BUS_ADRALN, regs->nip);
 496 }
 497
 498 #ifdef CONFIG_ALTIVEC
 499 void altivec_assist_exception(struct pt_regs *regs)
 500 {
 501         int err;
 502         siginfo_t info;
 503
 504         if (!user_mode(regs)) {
 505                 printk(KERN_EMERG "VMX/Altivec assist exception in kernel mode"
 506                        " at %lx\n", regs->nip);
 507                 die("Kernel VMX/Altivec assist exception", regs, SIGILL);
 508         }
 509
 510         flush_altivec_to_thread(current);
 511
 512         err = emulate_altivec(regs);
 513         if (err == 0) {
 514                 regs->nip += 4;         /* skip emulated instruction */
 515                 emulate_single_step(regs);
 516                 return;
 517         }
 518
 519         if (err == -EFAULT) {
 520                 /* got an error reading the instruction */
 521                 info.si_signo = SIGSEGV;
 522                 info.si_errno = 0;
 523                 info.si_code = SEGV_MAPERR;
 524                 info.si_addr = (void __user *) regs->nip;
 525                 force_sig_info(SIGSEGV, &info, current);
 526         } else {
 527                 /* didn't recognize the instruction */
 528                 /* XXX quick hack for now: set the non-Java bit in the VSCR */
 529                 if (printk_ratelimit())
 530                         printk(KERN_ERR "Unrecognized altivec instruction "
 531                                "in %s at %lx\n", current->comm, regs->nip);
 532                 current->thread.vscr.u[3] |= 0x10000;
 533         }
 534 }
 535 #endif /* CONFIG_ALTIVEC */
 536
 537 /*
 538  * We enter here if we get an unrecoverable exception, that is, one
 539  * that happened at a point where the RI (recoverable interrupt) bit
 540  * in the MSR is 0.  This indicates that SRR0/1 are live, and that
 541  * we therefore lost state by taking this exception.
 542  */
 543 void unrecoverable_exception(struct pt_regs *regs)
 544 {
 545         printk(KERN_EMERG "Unrecoverable exception %lx at %lx\n",
 546                regs->trap, regs->nip);
 547         die("Unrecoverable exception", regs, SIGABRT);
 548 }
 549
 550 /*
 551  * We enter here if we discover during exception entry that we are
 552  * running in supervisor mode with a userspace value in the stack pointer.
 553  */
 554 void kernel_bad_stack(struct pt_regs *regs)
 555 {
 556         printk(KERN_EMERG "Bad kernel stack pointer %lx at %lx\n",
 557                regs->gpr[1], regs->nip);
 558         die("Bad kernel stack pointer", regs, SIGABRT);
 559 }
 560
 561 void __init trap_init(void)
 562 {
 563 }