arch/hexagon/mm/vm_fault.c

   1 /*
   2  * Memory fault handling for Hexagon
   3  *
   4  * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 and
   8  * only version 2 as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  18  * 02110-1301, USA.
  19  */
  20
  21 /*
  22  * Page fault handling for the Hexagon Virtual Machine.
  23  * Can also be called by a native port emulating the HVM
  24  * execptions.
  25  */
  26
  27 #include <asm/pgtable.h>
  28 #include <asm/traps.h>
  29 #include <linux/uaccess.h>
  30 #include <linux/mm.h>
  31 #include <linux/sched/signal.h>
  32 #include <linux/signal.h>
  33 #include <linux/extable.h>
  34 #include <linux/hardirq.h>
  35
  36 /*
  37  * Decode of hardware exception sends us to one of several
  38  * entry points.  At each, we generate canonical arguments
  39  * for handling by the abstract memory management code.
  40  */
  41 #define FLT_IFETCH     -1
  42 #define FLT_LOAD        0
  43 #define FLT_STORE       1
  44
  45
  46 /*
  47  * Canonical page fault handler
  48  */
  49 void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)
  50 {
  51         struct vm_area_struct *vma;
  52         struct mm_struct *mm = current->mm;
  53         int si_signo;
  54         int si_code = SEGV_MAPERR;
  55         vm_fault_t fault;
  56         const struct exception_table_entry *fixup;
  57         unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
  58
  59         /*
  60          * If we're in an interrupt or have no user context,
  61          * then must not take the fault.
  62          */
  63         if (unlikely(in_interrupt() || !mm))
  64                 goto no_context;
  65
  66         local_irq_enable();
  67
  68         if (user_mode(regs))
  69                 flags |= FAULT_FLAG_USER;
  70 retry:
  71         down_read(&mm->mmap_sem);
  72         vma = find_vma(mm, address);
  73         if (!vma)
  74                 goto bad_area;
  75
  76         if (vma->vm_start <= address)
  77                 goto good_area;
  78
  79         if (!(vma->vm_flags & VM_GROWSDOWN))
  80                 goto bad_area;
  81
  82         if (expand_stack(vma, address))
  83                 goto bad_area;
  84
  85 good_area:
  86         /* Address space is OK.  Now check access rights. */
  87         si_code = SEGV_ACCERR;
  88
  89         switch (cause) {
  90         case FLT_IFETCH:
  91                 if (!(vma->vm_flags & VM_EXEC))
  92                         goto bad_area;
  93                 break;
  94         case FLT_LOAD:
  95                 if (!(vma->vm_flags & VM_READ))
  96                         goto bad_area;
  97                 break;
  98         case FLT_STORE:
  99                 if (!(vma->vm_flags & VM_WRITE))
 100                         goto bad_area;
 101                 flags |= FAULT_FLAG_WRITE;
 102                 break;
 103         }
 104
 105         fault = handle_mm_fault(vma, address, flags);
 106
 107         if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 108                 return;
 109
 110         /* The most common case -- we are done. */
 111         if (likely(!(fault & VM_FAULT_ERROR))) {
 112                 if (flags & FAULT_FLAG_ALLOW_RETRY) {
 113                         if (fault & VM_FAULT_MAJOR)
 114                                 current->maj_flt++;
 115                         else
 116                                 current->min_flt++;
 117                         if (fault & VM_FAULT_RETRY) {
 118                                 flags &= ~FAULT_FLAG_ALLOW_RETRY;
 119                                 flags |= FAULT_FLAG_TRIED;
 120                                 goto retry;
 121                         }
 122                 }
 123
 124                 up_read(&mm->mmap_sem);
 125                 return;
 126         }
 127
 128         up_read(&mm->mmap_sem);
 129
 130         /* Handle copyin/out exception cases */
 131         if (!user_mode(regs))
 132                 goto no_context;
 133
 134         if (fault & VM_FAULT_OOM) {
 135                 pagefault_out_of_memory();
 136                 return;
 137         }
 138
 139         /* User-mode address is in the memory map, but we are
 140          * unable to fix up the page fault.
 141          */
 142         if (fault & VM_FAULT_SIGBUS) {
 143                 si_signo = SIGBUS;
 144                 si_code = BUS_ADRERR;
 145         }
 146         /* Address is not in the memory map */
 147         else {
 148                 si_signo = SIGSEGV;
 149                 si_code  = SEGV_ACCERR;
 150         }
 151         force_sig_fault(si_signo, si_code, (void __user *)address, current);
 152         return;
 153
 154 bad_area:
 155         up_read(&mm->mmap_sem);
 156
 157         if (user_mode(regs)) {
 158                 force_sig_fault(SIGSEGV, si_code, (void __user *)address, current);
 159                 return;
 160         }
 161         /* Kernel-mode fault falls through */
 162
 163 no_context:
 164         fixup = search_exception_tables(pt_elr(regs));
 165         if (fixup) {
 166                 pt_set_elr(regs, fixup->fixup);
 167                 return;
 168         }
 169
 170         /* Things are looking very, very bad now */
 171         bust_spinlocks(1);
 172         printk(KERN_EMERG "Unable to handle kernel paging request at "
 173                 "virtual address 0x%08lx, regs %p\n", address, regs);
 174         die("Bad Kernel VA", regs, SIGKILL);
 175 }
 176
 177
 178 void read_protection_fault(struct pt_regs *regs)
 179 {
 180         unsigned long badvadr = pt_badva(regs);
 181
 182         do_page_fault(badvadr, FLT_LOAD, regs);
 183 }
 184
 185 void write_protection_fault(struct pt_regs *regs)
 186 {
 187         unsigned long badvadr = pt_badva(regs);
 188
 189         do_page_fault(badvadr, FLT_STORE, regs);
 190 }
 191
 192 void execute_protection_fault(struct pt_regs *regs)
 193 {
 194         unsigned long badvadr = pt_badva(regs);
 195
 196         do_page_fault(badvadr, FLT_IFETCH, regs);
 197 }