arch/hexagon/mm/vm_fault.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Memory fault handling for Hexagon
   4  *
   5  * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
   6  */
   7
   8 /*
   9  * Page fault handling for the Hexagon Virtual Machine.
  10  * Can also be called by a native port emulating the HVM
  11  * execptions.
  12  */
  13
  14 #include <asm/pgtable.h>
  15 #include <asm/traps.h>
  16 #include <linux/uaccess.h>
  17 #include <linux/mm.h>
  18 #include <linux/sched/signal.h>
  19 #include <linux/signal.h>
  20 #include <linux/extable.h>
  21 #include <linux/hardirq.h>
  22
  23 /*
  24  * Decode of hardware exception sends us to one of several
  25  * entry points.  At each, we generate canonical arguments
  26  * for handling by the abstract memory management code.
  27  */
  28 #define FLT_IFETCH     -1
  29 #define FLT_LOAD        0
  30 #define FLT_STORE       1
  31
  32
  33 /*
  34  * Canonical page fault handler
  35  */
  36 void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)
  37 {
  38         struct vm_area_struct *vma;
  39         struct mm_struct *mm = current->mm;
  40         int si_signo;
  41         int si_code = SEGV_MAPERR;
  42         vm_fault_t fault;
  43         const struct exception_table_entry *fixup;
  44         unsigned int flags = FAULT_FLAG_DEFAULT;
  45
  46         /*
  47          * If we're in an interrupt or have no user context,
  48          * then must not take the fault.
  49          */
  50         if (unlikely(in_interrupt() || !mm))
  51                 goto no_context;
  52
  53         local_irq_enable();
  54
  55         if (user_mode(regs))
  56                 flags |= FAULT_FLAG_USER;
  57 retry:
  58         down_read(&mm->mmap_sem);
  59         vma = find_vma(mm, address);
  60         if (!vma)
  61                 goto bad_area;
  62
  63         if (vma->vm_start <= address)
  64                 goto good_area;
  65
  66         if (!(vma->vm_flags & VM_GROWSDOWN))
  67                 goto bad_area;
  68
  69         if (expand_stack(vma, address))
  70                 goto bad_area;
  71
  72 good_area:
  73         /* Address space is OK.  Now check access rights. */
  74         si_code = SEGV_ACCERR;
  75
  76         switch (cause) {
  77         case FLT_IFETCH:
  78                 if (!(vma->vm_flags & VM_EXEC))
  79                         goto bad_area;
  80                 break;
  81         case FLT_LOAD:
  82                 if (!(vma->vm_flags & VM_READ))
  83                         goto bad_area;
  84                 break;
  85         case FLT_STORE:
  86                 if (!(vma->vm_flags & VM_WRITE))
  87                         goto bad_area;
  88                 flags |= FAULT_FLAG_WRITE;
  89                 break;
  90         }
  91
  92         fault = handle_mm_fault(vma, address, flags);
  93
  94         if (fault_signal_pending(fault, regs))
  95                 return;
  96
  97         /* The most common case -- we are done. */
  98         if (likely(!(fault & VM_FAULT_ERROR))) {
  99                 if (flags & FAULT_FLAG_ALLOW_RETRY) {
 100                         if (fault & VM_FAULT_MAJOR)
 101                                 current->maj_flt++;
 102                         else
 103                                 current->min_flt++;
 104                         if (fault & VM_FAULT_RETRY) {
 105                                 flags |= FAULT_FLAG_TRIED;
 106                                 goto retry;
 107                         }
 108                 }
 109
 110                 up_read(&mm->mmap_sem);
 111                 return;
 112         }
 113
 114         up_read(&mm->mmap_sem);
 115
 116         /* Handle copyin/out exception cases */
 117         if (!user_mode(regs))
 118                 goto no_context;
 119
 120         if (fault & VM_FAULT_OOM) {
 121                 pagefault_out_of_memory();
 122                 return;
 123         }
 124
 125         /* User-mode address is in the memory map, but we are
 126          * unable to fix up the page fault.
 127          */
 128         if (fault & VM_FAULT_SIGBUS) {
 129                 si_signo = SIGBUS;
 130                 si_code = BUS_ADRERR;
 131         }
 132         /* Address is not in the memory map */
 133         else {
 134                 si_signo = SIGSEGV;
 135                 si_code  = SEGV_ACCERR;
 136         }
 137         force_sig_fault(si_signo, si_code, (void __user *)address);
 138         return;
 139
 140 bad_area:
 141         up_read(&mm->mmap_sem);
 142
 143         if (user_mode(regs)) {
 144                 force_sig_fault(SIGSEGV, si_code, (void __user *)address);
 145                 return;
 146         }
 147         /* Kernel-mode fault falls through */
 148
 149 no_context:
 150         fixup = search_exception_tables(pt_elr(regs));
 151         if (fixup) {
 152                 pt_set_elr(regs, fixup->fixup);
 153                 return;
 154         }
 155
 156         /* Things are looking very, very bad now */
 157         bust_spinlocks(1);
 158         printk(KERN_EMERG "Unable to handle kernel paging request at "
 159                 "virtual address 0x%08lx, regs %p\n", address, regs);
 160         die("Bad Kernel VA", regs, SIGKILL);
 161 }
 162
 163
 164 void read_protection_fault(struct pt_regs *regs)
 165 {
 166         unsigned long badvadr = pt_badva(regs);
 167
 168         do_page_fault(badvadr, FLT_LOAD, regs);
 169 }
 170
 171 void write_protection_fault(struct pt_regs *regs)
 172 {
 173         unsigned long badvadr = pt_badva(regs);
 174
 175         do_page_fault(badvadr, FLT_STORE, regs);
 176 }
 177
 178 void execute_protection_fault(struct pt_regs *regs)
 179 {
 180         unsigned long badvadr = pt_badva(regs);
 181
 182         do_page_fault(badvadr, FLT_IFETCH, regs);
 183 }