arch/sparc/mm/fault.c

   1 /* $Id: fault.c,v 1.114 2000/02/14 04:52:36 jj Exp $
   2  * fault.c:  Page fault handlers for the Sparc.
   3  *
   4  * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
   5  * Copyright (C) 1996 Eddie C. Dost (ecd@skynet.be)
   6  * Copyright (C) 1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
   7  */
   8
   9 #include <asm/head.h>
  10
  11 #include <linux/string.h>
  12 #include <linux/types.h>
  13 #include <linux/ptrace.h>
  14 #include <linux/mman.h>
  15 #include <linux/threads.h>
  16 #include <linux/kernel.h>
  17 #include <linux/signal.h>
  18 #include <linux/mm.h>
  19 #include <linux/smp.h>
  20 #include <linux/smp_lock.h>
  21 #include <linux/interrupt.h>
  22
  23 #include <asm/system.h>
  24 #include <asm/segment.h>
  25 #include <asm/page.h>
  26 #include <asm/pgtable.h>
  27 #include <asm/memreg.h>
  28 #include <asm/openprom.h>
  29 #include <asm/oplib.h>
  30 #include <asm/smp.h>
  31 #include <asm/traps.h>
  32 #include <asm/kdebug.h>
  33 #include <asm/uaccess.h>
  34
  35 #define ELEMENTS(arr) (sizeof (arr)/sizeof (arr[0]))
  36
  37 extern struct sparc_phys_banks sp_banks[SPARC_PHYS_BANKS];
  38 extern int prom_node_root;
  39
  40 struct linux_romvec *romvec;
  41
  42 /* At boot time we determine these two values necessary for setting
  43  * up the segment maps and page table entries (pte's).
  44  */
  45
  46 int num_segmaps, num_contexts;
  47 int invalid_segment;
  48
  49 /* various Virtual Address Cache parameters we find at boot time... */
  50
  51 int vac_size, vac_linesize, vac_do_hw_vac_flushes;
  52 int vac_entries_per_context, vac_entries_per_segment;
  53 int vac_entries_per_page;
  54
  55 /* Nice, simple, prom library does all the sweating for us. ;) */
  56 int prom_probe_memory (void)
  57 {
  58         register struct linux_mlist_v0 *mlist;
  59         register unsigned long bytes, base_paddr, tally;
  60         register int i;
  61
  62         i = 0;
  63         mlist= *prom_meminfo()->v0_available;
  64         bytes = tally = mlist->num_bytes;
  65         base_paddr = (unsigned long) mlist->start_adr;
  66
  67         sp_banks[0].base_addr = base_paddr;
  68         sp_banks[0].num_bytes = bytes;
  69
  70         while (mlist->theres_more != (void *) 0){
  71                 i++;
  72                 mlist = mlist->theres_more;
  73                 bytes = mlist->num_bytes;
  74                 tally += bytes;
  75                 if (i >= SPARC_PHYS_BANKS-1) {
  76                         printk ("The machine has more banks than "
  77                                 "this kernel can support\n"
  78                                 "Increase the SPARC_PHYS_BANKS "
  79                                 "setting (currently %d)\n",
  80                                 SPARC_PHYS_BANKS);
  81                         i = SPARC_PHYS_BANKS-1;
  82                         break;
  83                 }
  84
  85                 sp_banks[i].base_addr = (unsigned long) mlist->start_adr;
  86                 sp_banks[i].num_bytes = mlist->num_bytes;
  87         }
  88
  89         i++;
  90         sp_banks[i].base_addr = 0xdeadbeef;
  91         sp_banks[i].num_bytes = 0;
  92
  93         /* Now mask all bank sizes on a page boundary, it is all we can
  94          * use anyways.
  95          */
  96         for(i=0; sp_banks[i].num_bytes != 0; i++)
  97                 sp_banks[i].num_bytes &= PAGE_MASK;
  98
  99         return tally;
 100 }
 101
 102 /* Traverse the memory lists in the prom to see how much physical we
 103  * have.
 104  */
 105 unsigned long
 106 probe_memory(void)
 107 {
 108         int total;
 109
 110         total = prom_probe_memory();
 111
 112         /* Oh man, much nicer, keep the dirt in promlib. */
 113         return total;
 114 }
 115
 116 extern void sun4c_complete_all_stores(void);
 117
 118 /* Whee, a level 15 NMI interrupt memory error.  Let's have fun... */
 119 asmlinkage void sparc_lvl15_nmi(struct pt_regs *regs, unsigned long serr,
 120                                 unsigned long svaddr, unsigned long aerr,
 121                                 unsigned long avaddr)
 122 {
 123         sun4c_complete_all_stores();
 124         printk("FAULT: NMI received\n");
 125         printk("SREGS: Synchronous Error %08lx\n", serr);
 126         printk("       Synchronous Vaddr %08lx\n", svaddr);
 127         printk("      Asynchronous Error %08lx\n", aerr);
 128         printk("      Asynchronous Vaddr %08lx\n", avaddr);
 129         if (sun4c_memerr_reg)
 130                 printk("     Memory Parity Error %08lx\n", *sun4c_memerr_reg);
 131         printk("REGISTER DUMP:\n");
 132         show_regs(regs);
 133         prom_halt();
 134 }
 135
 136 static void unhandled_fault(unsigned long, struct task_struct *,
 137                 struct pt_regs *) __attribute__ ((noreturn));
 138
 139 static void unhandled_fault(unsigned long address, struct task_struct *tsk,
 140                      struct pt_regs *regs)
 141 {
 142         if((unsigned long) address < PAGE_SIZE) {
 143                 printk(KERN_ALERT "Unable to handle kernel NULL "
 144                        "pointer dereference");
 145         } else {
 146                 printk(KERN_ALERT "Unable to handle kernel paging request "
 147                        "at virtual address %08lx\n", address);
 148         }
 149         printk(KERN_ALERT "tsk->{mm,active_mm}->context = %08lx\n",
 150                 (tsk->mm ? tsk->mm->context : tsk->active_mm->context));
 151         printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %08lx\n",
 152                 (tsk->mm ? (unsigned long) tsk->mm->pgd :
 153                         (unsigned long) tsk->active_mm->pgd));
 154         die_if_kernel("Oops", regs);
 155 }
 156
 157 asmlinkage int lookup_fault(unsigned long pc, unsigned long ret_pc,
 158                             unsigned long address)
 159 {
 160         unsigned long g2;
 161         int i;
 162         unsigned insn;
 163         struct pt_regs regs;
 164
 165         i = search_exception_table (ret_pc, &g2);
 166         switch (i) {
 167         /* load & store will be handled by fixup */
 168         case 3: return 3;
 169         /* store will be handled by fixup, load will bump out */
 170         /* for _to_ macros */
 171         case 1: insn = (unsigned)pc; if ((insn >> 21) & 1) return 1; break;
 172         /* load will be handled by fixup, store will bump out */
 173         /* for _from_ macros */
 174         case 2: insn = (unsigned)pc;
 175                 if (!((insn >> 21) & 1) || ((insn>>19)&0x3f) == 15) return 2;
 176                 break;
 177         default: break;
 178         }
 179         memset (&regs, 0, sizeof (regs));
 180         regs.pc = pc;
 181         regs.npc = pc + 4;
 182         __asm__ __volatile__ ("
 183                 rd %%psr, %0
 184                 nop
 185                 nop
 186                 nop" : "=r" (regs.psr));
 187         unhandled_fault (address, current, &regs);
 188         /* Not reached */
 189         return 0;
 190 }
 191
 192 asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
 193                                unsigned long address)
 194 {
 195         struct vm_area_struct *vma;
 196         struct task_struct *tsk = current;
 197         struct mm_struct *mm = tsk->mm;
 198         unsigned int fixup;
 199         unsigned long g2;
 200         siginfo_t info;
 201         int from_user = !(regs->psr & PSR_PS);
 202
 203         info.si_code = SEGV_MAPERR;
 204         if(text_fault)
 205                 address = regs->pc;
 206
 207         /*
 208          * If we're in an interrupt or have no user
 209          * context, we must not take the fault..
 210          */
 211         if (in_interrupt() || !mm)
 212                 goto no_context;
 213
 214         down(&mm->mmap_sem);
 215
 216         /*
 217          * The kernel referencing a bad kernel pointer can lock up
 218          * a sun4c machine completely, so we must attempt recovery.
 219          */
 220         if(!from_user && address >= PAGE_OFFSET)
 221                 goto bad_area;
 222
 223         vma = find_vma(mm, address);
 224         if(!vma)
 225                 goto bad_area;
 226         if(vma->vm_start <= address)
 227                 goto good_area;
 228         if(!(vma->vm_flags & VM_GROWSDOWN))
 229                 goto bad_area;
 230         if(expand_stack(vma, address))
 231                 goto bad_area;
 232         /*
 233          * Ok, we have a good vm_area for this memory access, so
 234          * we can handle it..
 235          */
 236 good_area:
 237         info.si_code = SEGV_ACCERR;
 238         if(write) {
 239                 if(!(vma->vm_flags & VM_WRITE))
 240                         goto bad_area;
 241         } else {
 242                 /* Allow reads even for write-only mappings */
 243                 if(!(vma->vm_flags & (VM_READ | VM_EXEC)))
 244                         goto bad_area;
 245         }
 246
 247         /*
 248          * If for any reason at all we couldn't handle the fault,
 249          * make sure we exit gracefully rather than endlessly redo
 250          * the fault.
 251          */
 252         {
 253                 int fault = handle_mm_fault(tsk, vma, address, write);
 254                 if (fault < 0)
 255                         goto out_of_memory;
 256                 if (!fault)
 257                         goto do_sigbus;
 258         }
 259         up(&mm->mmap_sem);
 260         return;
 261
 262         /*
 263          * Something tried to access memory that isn't in our memory map..
 264          * Fix it, but check if it's kernel or user first..
 265          */
 266 bad_area:
 267         up(&mm->mmap_sem);
 268
 269         /* User mode accesses just cause a SIGSEGV */
 270         if(from_user) {
 271 #if 0
 272                 printk("Fault whee %s [%d]: segfaults at %08lx pc=%08lx\n",
 273                        tsk->comm, tsk->pid, address, regs->pc);
 274 #endif
 275                 info.si_signo = SIGSEGV;
 276                 info.si_errno = 0;
 277                 /* info.si_code set above to make clear whether
 278                    this was a SEGV_MAPERR or SEGV_ACCERR fault.  */
 279                 info.si_addr = (void *)address;
 280                 info.si_trapno = 0;
 281                 force_sig_info (SIGSEGV, &info, tsk);
 282                 return;
 283         }
 284
 285         /* Is this in ex_table? */
 286 no_context:
 287         g2 = regs->u_regs[UREG_G2];
 288         if (!from_user && (fixup = search_exception_table (regs->pc, &g2))) {
 289                 if (fixup > 10) { /* Values below are reserved for other things */
 290                         extern const unsigned __memset_start[];
 291                         extern const unsigned __memset_end[];
 292                         extern const unsigned __csum_partial_copy_start[];
 293                         extern const unsigned __csum_partial_copy_end[];
 294
 295 #ifdef DEBUG_EXCEPTIONS
 296                         printk("Exception: PC<%08lx> faddr<%08lx>\n", regs->pc, address);
 297                         printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n",
 298                                 regs->pc, fixup, g2);
 299 #endif
 300                         if ((regs->pc >= (unsigned long)__memset_start &&
 301                              regs->pc < (unsigned long)__memset_end) ||
 302                             (regs->pc >= (unsigned long)__csum_partial_copy_start &&
 303                              regs->pc < (unsigned long)__csum_partial_copy_end)) {
 304                                 regs->u_regs[UREG_I4] = address;
 305                                 regs->u_regs[UREG_I5] = regs->pc;
 306                         }
 307                         regs->u_regs[UREG_G2] = g2;
 308                         regs->pc = fixup;
 309                         regs->npc = regs->pc + 4;
 310                         return;
 311                 }
 312         }
 313
 314         unhandled_fault (address, tsk, regs);
 315         do_exit(SIGKILL);
 316
 317 /*
 318  * We ran out of memory, or some other thing happened to us that made
 319  * us unable to handle the page fault gracefully.
 320  */
 321 out_of_memory:
 322         up(&mm->mmap_sem);
 323         printk("VM: killing process %s\n", tsk->comm);
 324         if (from_user)
 325                 do_exit(SIGKILL);
 326         goto no_context;
 327
 328 do_sigbus:
 329         up(&mm->mmap_sem);
 330         info.si_signo = SIGBUS;
 331         info.si_errno = 0;
 332         info.si_code = BUS_ADRERR;
 333         info.si_addr = (void *)address;
 334         info.si_trapno = 0;
 335         force_sig_info (SIGBUS, &info, tsk);
 336         if (!from_user)
 337                 goto no_context;
 338 }
 339
 340 asmlinkage void do_sun4c_fault(struct pt_regs *regs, int text_fault, int write,
 341                                unsigned long address)
 342 {
 343         extern void sun4c_update_mmu_cache(struct vm_area_struct *,
 344                                            unsigned long,pte_t);
 345         extern pte_t *sun4c_pte_offset(pmd_t *,unsigned long);
 346         struct task_struct *tsk = current;
 347         struct mm_struct *mm = tsk->mm;
 348         pgd_t *pgdp;
 349         pte_t *ptep;
 350
 351         if (text_fault) {
 352                 address = regs->pc;
 353         } else if (!write &&
 354                    !(regs->psr & PSR_PS)) {
 355                 unsigned int insn, *ip;
 356
 357                 ip = (unsigned int *)regs->pc;
 358                 if (! get_user(insn, ip)) {
 359                         if ((insn & 0xc1680000) == 0xc0680000)
 360                                 write = 1;
 361                 }
 362         }
 363
 364         pgdp = pgd_offset(mm, address);
 365         ptep = sun4c_pte_offset((pmd_t *) pgdp, address);
 366
 367         if (pgd_val(*pgdp)) {
 368             if (write) {
 369                 if ((pte_val(*ptep) & (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT))
 370                                    == (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT)) {
 371                         unsigned long flags;
 372
 373                         *ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED |
 374                                       _SUN4C_PAGE_MODIFIED |
 375                                       _SUN4C_PAGE_VALID |
 376                                       _SUN4C_PAGE_DIRTY);
 377
 378                         save_and_cli(flags);
 379                         if (sun4c_get_segmap(address) != invalid_segment) {
 380                                 sun4c_put_pte(address, pte_val(*ptep));
 381                                 restore_flags(flags);
 382                                 return;
 383                         }
 384                         restore_flags(flags);
 385                 }
 386             } else {
 387                 if ((pte_val(*ptep) & (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT))
 388                                    == (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT)) {
 389                         unsigned long flags;
 390
 391                         *ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED |
 392                                       _SUN4C_PAGE_VALID);
 393
 394                         save_and_cli(flags);
 395                         if (sun4c_get_segmap(address) != invalid_segment) {
 396                                 sun4c_put_pte(address, pte_val(*ptep));
 397                                 restore_flags(flags);
 398                                 return;
 399                         }
 400                         restore_flags(flags);
 401                 }
 402             }
 403         }
 404
 405         /* This conditional is 'interesting'. */
 406         if (pgd_val(*pgdp) && !(write && !(pte_val(*ptep) & _SUN4C_PAGE_WRITE))
 407             && (pte_val(*ptep) & _SUN4C_PAGE_VALID))
 408                 /* Note: It is safe to not grab the MMAP semaphore here because
 409                  *       we know that update_mmu_cache() will not sleep for
 410                  *       any reason (at least not in the current implementation)
 411                  *       and therefore there is no danger of another thread getting
 412                  *       on the CPU and doing a shrink_mmap() on this vma.
 413                  */
 414                 sun4c_update_mmu_cache (find_vma(current->mm, address), address,
 415                                         *ptep);
 416         else
 417                 do_sparc_fault(regs, text_fault, write, address);
 418 }
 419
 420 /* This always deals with user addresses. */
 421 inline void force_user_fault(unsigned long address, int write)
 422 {
 423         struct vm_area_struct *vma;
 424         struct task_struct *tsk = current;
 425         struct mm_struct *mm = tsk->mm;
 426         siginfo_t info;
 427
 428         info.si_code = SEGV_MAPERR;
 429
 430 #if 0
 431         printk("wf<pid=%d,wr=%d,addr=%08lx>\n",
 432                tsk->pid, write, address);
 433 #endif
 434         down(&mm->mmap_sem);
 435         vma = find_vma(mm, address);
 436         if(!vma)
 437                 goto bad_area;
 438         if(vma->vm_start <= address)
 439                 goto good_area;
 440         if(!(vma->vm_flags & VM_GROWSDOWN))
 441                 goto bad_area;
 442         if(expand_stack(vma, address))
 443                 goto bad_area;
 444 good_area:
 445         info.si_code = SEGV_ACCERR;
 446         if(write) {
 447                 if(!(vma->vm_flags & VM_WRITE))
 448                         goto bad_area;
 449         } else {
 450                 if(!(vma->vm_flags & (VM_READ | VM_EXEC)))
 451                         goto bad_area;
 452         }
 453         if (!handle_mm_fault(current, vma, address, write))
 454                 goto do_sigbus;
 455         up(&mm->mmap_sem);
 456         return;
 457 bad_area:
 458         up(&mm->mmap_sem);
 459 #if 0
 460         printk("Window whee %s [%d]: segfaults at %08lx\n",
 461                tsk->comm, tsk->pid, address);
 462 #endif
 463         info.si_signo = SIGSEGV;
 464         info.si_errno = 0;
 465         /* info.si_code set above to make clear whether
 466            this was a SEGV_MAPERR or SEGV_ACCERR fault.  */
 467         info.si_addr = (void *)address;
 468         info.si_trapno = 0;
 469         force_sig_info (SIGSEGV, &info, tsk);
 470         return;
 471
 472 do_sigbus:
 473         up(&mm->mmap_sem);
 474         info.si_signo = SIGBUS;
 475         info.si_errno = 0;
 476         info.si_code = BUS_ADRERR;
 477         info.si_addr = (void *)address;
 478         info.si_trapno = 0;
 479         force_sig_info (SIGBUS, &info, tsk);
 480 }
 481
 482 void window_overflow_fault(void)
 483 {
 484         unsigned long sp;
 485
 486         sp = current->thread.rwbuf_stkptrs[0];
 487         if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 488                 force_user_fault(sp + 0x38, 1);
 489         force_user_fault(sp, 1);
 490 }
 491
 492 void window_underflow_fault(unsigned long sp)
 493 {
 494         if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 495                 force_user_fault(sp + 0x38, 0);
 496         force_user_fault(sp, 0);
 497 }
 498
 499 void window_ret_fault(struct pt_regs *regs)
 500 {
 501         unsigned long sp;
 502
 503         sp = regs->u_regs[UREG_FP];
 504         if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 505                 force_user_fault(sp + 0x38, 0);
 506         force_user_fault(sp, 0);
 507 }