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/traps.h>
  15 #include <linux/uaccess.h>
  16 #include <linux/mm.h>
  17 #include <linux/sched/signal.h>
  18 #include <linux/signal.h>
  19 #include <linux/extable.h>
  20 #include <linux/hardirq.h>
  21 #include <linux/perf_event.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
  58         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
  59 retry:
  60         mmap_read_lock(mm);
  61         vma = find_vma(mm, address);
  62         if (!vma)
  63                 goto bad_area;
  64
  65         if (vma->vm_start <= address)
  66                 goto good_area;
  67
  68         if (!(vma->vm_flags & VM_GROWSDOWN))
  69                 goto bad_area;
  70
  71         if (expand_stack(vma, address))
  72                 goto bad_area;
  73
  74 good_area:
  75         /* Address space is OK.  Now check access rights. */
  76         si_code = SEGV_ACCERR;
  77
  78         switch (cause) {
  79         case FLT_IFETCH:
  80                 if (!(vma->vm_flags & VM_EXEC))
  81                         goto bad_area;
  82                 break;
  83         case FLT_LOAD:
  84                 if (!(vma->vm_flags & VM_READ))
  85                         goto bad_area;
  86                 break;
  87         case FLT_STORE:
  88                 if (!(vma->vm_flags & VM_WRITE))
  89                         goto bad_area;
  90                 flags |= FAULT_FLAG_WRITE;
  91                 break;
  92         }
  93
  94         fault = handle_mm_fault(vma, address, flags, regs);
  95
  96         if (fault_signal_pending(fault, regs))
  97                 return;
  98
  99         /* The most common case -- we are done. */
 100         if (likely(!(fault & VM_FAULT_ERROR))) {
 101                 if (flags & FAULT_FLAG_ALLOW_RETRY) {
 102                         if (fault & VM_FAULT_RETRY) {
 103                                 flags |= FAULT_FLAG_TRIED;
 104                                 goto retry;
 105                         }
 106                 }
 107
 108                 mmap_read_unlock(mm);
 109                 return;
 110         }
 111
 112         mmap_read_unlock(mm);
 113
 114         /* Handle copyin/out exception cases */
 115         if (!user_mode(regs))
 116                 goto no_context;
 117
 118         if (fault & VM_FAULT_OOM) {
 119                 pagefault_out_of_memory();
 120                 return;
 121         }
 122
 123         /* User-mode address is in the memory map, but we are
 124          * unable to fix up the page fault.
 125          */
 126         if (fault & VM_FAULT_SIGBUS) {
 127                 si_signo = SIGBUS;
 128                 si_code = BUS_ADRERR;
 129         }
 130         /* Address is not in the memory map */
 131         else {
 132                 si_signo = SIGSEGV;
 133                 si_code  = SEGV_ACCERR;
 134         }
 135         force_sig_fault(si_signo, si_code, (void __user *)address);
 136         return;
 137
 138 bad_area:
 139         mmap_read_unlock(mm);
 140
 141         if (user_mode(regs)) {
 142                 force_sig_fault(SIGSEGV, si_code, (void __user *)address);
 143                 return;
 144         }
 145         /* Kernel-mode fault falls through */
 146
 147 no_context:
 148         fixup = search_exception_tables(pt_elr(regs));
 149         if (fixup) {
 150                 pt_set_elr(regs, fixup->fixup);
 151                 return;
 152         }
 153
 154         /* Things are looking very, very bad now */
 155         bust_spinlocks(1);
 156         printk(KERN_EMERG "Unable to handle kernel paging request at "
 157                 "virtual address 0x%08lx, regs %p\n", address, regs);
 158         die("Bad Kernel VA", regs, SIGKILL);
 159 }
 160
 161
 162 void read_protection_fault(struct pt_regs *regs)
 163 {
 164         unsigned long badvadr = pt_badva(regs);
 165
 166         do_page_fault(badvadr, FLT_LOAD, regs);
 167 }
 168
 169 void write_protection_fault(struct pt_regs *regs)
 170 {
 171         unsigned long badvadr = pt_badva(regs);
 172
 173         do_page_fault(badvadr, FLT_STORE, regs);
 174 }
 175
 176 void execute_protection_fault(struct pt_regs *regs)
 177 {
 178         unsigned long badvadr = pt_badva(regs);
 179
 180         do_page_fault(badvadr, FLT_IFETCH, regs);
 181 }