root/arch/hexagon/mm/vm_fault.c

DEFINITIONS

1. do_page_fault
2. read_protection_fault
3. write_protection_fault
4. execute_protection_fault

   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_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
  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 & VM_FAULT_RETRY) && fatal_signal_pending(current))
  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_ALLOW_RETRY;
 106                                 flags |= FAULT_FLAG_TRIED;
 107                                 goto retry;
 108                         }
 109                 }
 110 
 111                 up_read(&mm->mmap_sem);
 112                 return;
 113         }
 114 
 115         up_read(&mm->mmap_sem);
 116 
 117         /* Handle copyin/out exception cases */
 118         if (!user_mode(regs))
 119                 goto no_context;
 120 
 121         if (fault & VM_FAULT_OOM) {
 122                 pagefault_out_of_memory();
 123                 return;
 124         }
 125 
 126         /* User-mode address is in the memory map, but we are
 127          * unable to fix up the page fault.
 128          */
 129         if (fault & VM_FAULT_SIGBUS) {
 130                 si_signo = SIGBUS;
 131                 si_code = BUS_ADRERR;
 132         }
 133         /* Address is not in the memory map */
 134         else {
 135                 si_signo = SIGSEGV;
 136                 si_code  = SEGV_ACCERR;
 137         }
 138         force_sig_fault(si_signo, si_code, (void __user *)address);
 139         return;
 140 
 141 bad_area:
 142         up_read(&mm->mmap_sem);
 143 
 144         if (user_mode(regs)) {
 145                 force_sig_fault(SIGSEGV, si_code, (void __user *)address);
 146                 return;
 147         }
 148         /* Kernel-mode fault falls through */
 149 
 150 no_context:
 151         fixup = search_exception_tables(pt_elr(regs));
 152         if (fixup) {
 153                 pt_set_elr(regs, fixup->fixup);
 154                 return;
 155         }
 156 
 157         /* Things are looking very, very bad now */
 158         bust_spinlocks(1);
 159         printk(KERN_EMERG "Unable to handle kernel paging request at "
 160                 "virtual address 0x%08lx, regs %p\n", address, regs);
 161         die("Bad Kernel VA", regs, SIGKILL);
 162 }
 163 
 164 
 165 void read_protection_fault(struct pt_regs *regs)
 166 {
 167         unsigned long badvadr = pt_badva(regs);
 168 
 169         do_page_fault(badvadr, FLT_LOAD, regs);
 170 }
 171 
 172 void write_protection_fault(struct pt_regs *regs)
 173 {
 174         unsigned long badvadr = pt_badva(regs);
 175 
 176         do_page_fault(badvadr, FLT_STORE, regs);
 177 }
 178 
 179 void execute_protection_fault(struct pt_regs *regs)
 180 {
 181         unsigned long badvadr = pt_badva(regs);
 182 
 183         do_page_fault(badvadr, FLT_IFETCH, regs);
 184 }