arch/alpha/mm/fault.c

   1 /*
   2  *  linux/arch/alpha/mm/fault.c
   3  *
   4  *  Copyright (C) 1995  Linus Torvalds
   5  */
   6
   7 #include <linux/sched.h>
   8 #include <linux/kernel.h>
   9 #include <linux/mm.h>
  10
  11 #define __EXTERN_INLINE inline
  12 #include <asm/mmu_context.h>
  13 #include <asm/pgtable.h>
  14 #undef  __EXTERN_INLINE
  15
  16 #include <linux/signal.h>
  17 #include <linux/head.h>
  18 #include <linux/errno.h>
  19 #include <linux/string.h>
  20 #include <linux/types.h>
  21 #include <linux/ptrace.h>
  22 #include <linux/mman.h>
  23 #include <linux/smp.h>
  24 #include <linux/smp_lock.h>
  25
  26 #include <asm/system.h>
  27 #include <asm/uaccess.h>
  28
  29 extern void die_if_kernel(char *,struct pt_regs *,long, unsigned long *);
  30
  31
  32 #ifdef __SMP__
  33 unsigned long last_asn[NR_CPUS] = { /* gag */
  34   ASN_FIRST_VERSION +  (0 << WIDTH_HARDWARE_ASN),
  35   ASN_FIRST_VERSION +  (1 << WIDTH_HARDWARE_ASN),
  36   ASN_FIRST_VERSION +  (2 << WIDTH_HARDWARE_ASN),
  37   ASN_FIRST_VERSION +  (3 << WIDTH_HARDWARE_ASN),
  38   ASN_FIRST_VERSION +  (4 << WIDTH_HARDWARE_ASN),
  39   ASN_FIRST_VERSION +  (5 << WIDTH_HARDWARE_ASN),
  40   ASN_FIRST_VERSION +  (6 << WIDTH_HARDWARE_ASN),
  41   ASN_FIRST_VERSION +  (7 << WIDTH_HARDWARE_ASN),
  42   ASN_FIRST_VERSION +  (8 << WIDTH_HARDWARE_ASN),
  43   ASN_FIRST_VERSION +  (9 << WIDTH_HARDWARE_ASN),
  44   ASN_FIRST_VERSION + (10 << WIDTH_HARDWARE_ASN),
  45   ASN_FIRST_VERSION + (11 << WIDTH_HARDWARE_ASN),
  46   ASN_FIRST_VERSION + (12 << WIDTH_HARDWARE_ASN),
  47   ASN_FIRST_VERSION + (13 << WIDTH_HARDWARE_ASN),
  48   ASN_FIRST_VERSION + (14 << WIDTH_HARDWARE_ASN),
  49   ASN_FIRST_VERSION + (15 << WIDTH_HARDWARE_ASN),
  50   ASN_FIRST_VERSION + (16 << WIDTH_HARDWARE_ASN),
  51   ASN_FIRST_VERSION + (17 << WIDTH_HARDWARE_ASN),
  52   ASN_FIRST_VERSION + (18 << WIDTH_HARDWARE_ASN),
  53   ASN_FIRST_VERSION + (19 << WIDTH_HARDWARE_ASN),
  54   ASN_FIRST_VERSION + (20 << WIDTH_HARDWARE_ASN),
  55   ASN_FIRST_VERSION + (21 << WIDTH_HARDWARE_ASN),
  56   ASN_FIRST_VERSION + (22 << WIDTH_HARDWARE_ASN),
  57   ASN_FIRST_VERSION + (23 << WIDTH_HARDWARE_ASN),
  58   ASN_FIRST_VERSION + (24 << WIDTH_HARDWARE_ASN),
  59   ASN_FIRST_VERSION + (25 << WIDTH_HARDWARE_ASN),
  60   ASN_FIRST_VERSION + (26 << WIDTH_HARDWARE_ASN),
  61   ASN_FIRST_VERSION + (27 << WIDTH_HARDWARE_ASN),
  62   ASN_FIRST_VERSION + (28 << WIDTH_HARDWARE_ASN),
  63   ASN_FIRST_VERSION + (29 << WIDTH_HARDWARE_ASN),
  64   ASN_FIRST_VERSION + (30 << WIDTH_HARDWARE_ASN),
  65   ASN_FIRST_VERSION + (31 << WIDTH_HARDWARE_ASN)
  66 };
  67 #else
  68 unsigned long asn_cache = ASN_FIRST_VERSION;
  69 #endif /* __SMP__ */
  70
  71 /*
  72  * Select a new ASN for a task.
  73  */
  74
  75 void
  76 get_new_mmu_context(struct task_struct *p, struct mm_struct *mm)
  77 {
  78         unsigned long asn = asn_cache;
  79
  80         if ((asn & HARDWARE_ASN_MASK) < MAX_ASN)
  81                 ++asn;
  82         else {
  83                 tbiap();
  84                 imb();
  85                 asn = (asn & ~HARDWARE_ASN_MASK) + ASN_FIRST_VERSION;
  86         }
  87         asn_cache = asn;
  88         mm->context = asn;                      /* full version + asn */
  89         p->tss.asn = asn & HARDWARE_ASN_MASK;   /* just asn */
  90 }
  91
  92 /*
  93  * This routine handles page faults.  It determines the address,
  94  * and the problem, and then passes it off to handle_mm_fault().
  95  *
  96  * mmcsr:
  97  *      0 = translation not valid
  98  *      1 = access violation
  99  *      2 = fault-on-read
 100  *      3 = fault-on-execute
 101  *      4 = fault-on-write
 102  *
 103  * cause:
 104  *      -1 = instruction fetch
 105  *      0 = load
 106  *      1 = store
 107  *
 108  * Registers $9 through $15 are saved in a block just prior to `regs' and
 109  * are saved and restored around the call to allow exception code to
 110  * modify them.
 111  */
 112
 113 /* Macro for exception fixup code to access integer registers.  */
 114 #define dpf_reg(r)                                                      \
 115         (((unsigned long *)regs)[(r) <= 8 ? (r) : (r) <= 15 ? (r)-16 :  \
 116                                  (r) <= 18 ? (r)+8 : (r)-10])
 117
 118 asmlinkage void
 119 do_page_fault(unsigned long address, unsigned long mmcsr,
 120               long cause, struct pt_regs *regs)
 121 {
 122         struct vm_area_struct * vma;
 123         struct mm_struct *mm = current->mm;
 124         unsigned fixup;
 125
 126         /* As of EV6, a load into $31/$f31 is a prefetch, and never faults
 127            (or is suppressed by the PALcode).  Support that for older CPUs
 128            by ignoring such an instruction.  */
 129         if (cause == 0) {
 130                 unsigned int insn;
 131                 __get_user(insn, (unsigned int *)regs->pc);
 132                 if ((insn >> 21 & 0x1f) == 0x1f &&
 133                     /* ldq ldl ldt lds ldg ldf ldwu ldbu */
 134                     (1ul << (insn >> 26) & 0x30f00001400ul)) {
 135                         regs->pc += 4;
 136                         return;
 137                 }
 138         }
 139
 140         down(&mm->mmap_sem);
 141         lock_kernel();
 142         vma = find_vma(mm, address);
 143         if (!vma)
 144                 goto bad_area;
 145         if (vma->vm_start <= address)
 146                 goto good_area;
 147         if (!(vma->vm_flags & VM_GROWSDOWN))
 148                 goto bad_area;
 149         if (expand_stack(vma, address))
 150                 goto bad_area;
 151 /*
 152  * Ok, we have a good vm_area for this memory access, so
 153  * we can handle it..
 154  */
 155 good_area:
 156         if (cause < 0) {
 157                 if (!(vma->vm_flags & VM_EXEC))
 158                         goto bad_area;
 159         } else if (!cause) {
 160                 /* Allow reads even for write-only mappings */
 161                 if (!(vma->vm_flags & (VM_READ | VM_WRITE)))
 162                         goto bad_area;
 163         } else {
 164                 if (!(vma->vm_flags & VM_WRITE))
 165                         goto bad_area;
 166         }
 167         handle_mm_fault(current, vma, address, cause > 0);
 168         up(&mm->mmap_sem);
 169         goto out;
 170
 171 /*
 172  * Something tried to access memory that isn't in our memory map..
 173  * Fix it, but check if it's kernel or user first..
 174  */
 175 bad_area:
 176         up(&mm->mmap_sem);
 177
 178         if (user_mode(regs)) {
 179                 force_sig(SIGSEGV, current);
 180                 goto out;
 181         }
 182
 183         /* Are we prepared to handle this fault as an exception?  */
 184         if ((fixup = search_exception_table(regs->pc)) != 0) {
 185                 unsigned long newpc;
 186                 newpc = fixup_exception(dpf_reg, fixup, regs->pc);
 187                 printk("%s: Exception at [<%lx>] (%lx)\n",
 188                        current->comm, regs->pc, newpc);
 189                 regs->pc = newpc;
 190                 goto out;
 191         }
 192
 193 /*
 194  * Oops. The kernel tried to access some bad page. We'll have to
 195  * terminate things with extreme prejudice.
 196  */
 197         printk(KERN_ALERT "Unable to handle kernel paging request at "
 198                "virtual address %016lx\n", address);
 199         die_if_kernel("Oops", regs, cause, (unsigned long*)regs - 16);
 200         do_exit(SIGKILL);
 201  out:
 202         unlock_kernel();
 203 }
 204