arch/arc/mm/fault.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Page Fault Handling for ARC (TLB Miss / ProtV)
   3  *
   4  * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
   5  */
   6
   7 #include <linux/signal.h>
   8 #include <linux/interrupt.h>
   9 #include <linux/sched/signal.h>
  10 #include <linux/errno.h>
  11 #include <linux/ptrace.h>
  12 #include <linux/uaccess.h>
  13 #include <linux/kdebug.h>
  14 #include <linux/perf_event.h>
  15 #include <linux/mm_types.h>
  16 #include <asm/entry.h>
  17 #include <asm/mmu.h>
  18
  19 /*
  20  * kernel virtual address is required to implement vmalloc/pkmap/fixmap
  21  * Refer to asm/processor.h for System Memory Map
  22  *
  23  * It simply copies the PMD entry (pointer to 2nd level page table or hugepage)
  24  * from swapper pgdir to task pgdir. The 2nd level table/page is thus shared
  25  */
  26 noinline static int handle_kernel_vaddr_fault(unsigned long address)
  27 {
  28         /*
  29          * Synchronize this task's top level page-table
  30          * with the 'reference' page table.
  31          */
  32         pgd_t *pgd, *pgd_k;
  33         p4d_t *p4d, *p4d_k;
  34         pud_t *pud, *pud_k;
  35         pmd_t *pmd, *pmd_k;
  36
  37         pgd = pgd_offset(current->active_mm, address);
  38         pgd_k = pgd_offset_k(address);
  39
  40         if (pgd_none (*pgd_k))
  41                 goto bad_area;
  42         if (!pgd_present(*pgd))
  43                 set_pgd(pgd, *pgd_k);
  44
  45         p4d = p4d_offset(pgd, address);
  46         p4d_k = p4d_offset(pgd_k, address);
  47         if (p4d_none(*p4d_k))
  48                 goto bad_area;
  49         if (!p4d_present(*p4d))
  50                 set_p4d(p4d, *p4d_k);
  51
  52         pud = pud_offset(p4d, address);
  53         pud_k = pud_offset(p4d_k, address);
  54         if (pud_none(*pud_k))
  55                 goto bad_area;
  56         if (!pud_present(*pud))
  57                 set_pud(pud, *pud_k);
  58
  59         pmd = pmd_offset(pud, address);
  60         pmd_k = pmd_offset(pud_k, address);
  61         if (pmd_none(*pmd_k))
  62                 goto bad_area;
  63         if (!pmd_present(*pmd))
  64                 set_pmd(pmd, *pmd_k);
  65
  66         /* XXX: create the TLB entry here */
  67         return 0;
  68
  69 bad_area:
  70         return 1;
  71 }
  72
  73 void do_page_fault(unsigned long address, struct pt_regs *regs)
  74 {
  75         struct vm_area_struct *vma = NULL;
  76         struct task_struct *tsk = current;
  77         struct mm_struct *mm = tsk->mm;
  78         int sig, si_code = SEGV_MAPERR;
  79         unsigned int write = 0, exec = 0, mask;
  80         vm_fault_t fault = VM_FAULT_SIGSEGV;    /* handle_mm_fault() output */
  81         unsigned int flags;                     /* handle_mm_fault() input */
  82
  83         /*
  84          * NOTE! We MUST NOT take any locks for this case. We may
  85          * be in an interrupt or a critical region, and should
  86          * only copy the information from the master page table,
  87          * nothing more.
  88          */
  89         if (address >= VMALLOC_START && !user_mode(regs)) {
  90                 if (unlikely(handle_kernel_vaddr_fault(address)))
  91                         goto no_context;
  92                 else
  93                         return;
  94         }
  95
  96         /*
  97          * If we're in an interrupt or have no user
  98          * context, we must not take the fault..
  99          */
 100         if (faulthandler_disabled() || !mm)
 101                 goto no_context;
 102
 103         if (regs->ecr.cause & ECR_C_PROTV_STORE)        /* ST/EX */
 104                 write = 1;
 105         else if ((regs->ecr.vec == ECR_V_PROTV) &&
 106                  (regs->ecr.cause == ECR_C_PROTV_INST_FETCH))
 107                 exec = 1;
 108
 109         flags = FAULT_FLAG_DEFAULT;
 110         if (user_mode(regs))
 111                 flags |= FAULT_FLAG_USER;
 112         if (write)
 113                 flags |= FAULT_FLAG_WRITE;
 114
 115         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
 116 retry:
 117         vma = lock_mm_and_find_vma(mm, address, regs);
 118         if (!vma)
 119                 goto bad_area_nosemaphore;
 120
 121         /*
 122          * vm_area is good, now check permissions for this memory access
 123          */
 124         mask = VM_READ;
 125         if (write)
 126                 mask = VM_WRITE;
 127         if (exec)
 128                 mask = VM_EXEC;
 129
 130         if (!(vma->vm_flags & mask)) {
 131                 si_code = SEGV_ACCERR;
 132                 goto bad_area;
 133         }
 134
 135         fault = handle_mm_fault(vma, address, flags, regs);
 136
 137         /* Quick path to respond to signals */
 138         if (fault_signal_pending(fault, regs)) {
 139                 if (!user_mode(regs))
 140                         goto no_context;
 141                 return;
 142         }
 143
 144         /* The fault is fully completed (including releasing mmap lock) */
 145         if (fault & VM_FAULT_COMPLETED)
 146                 return;
 147
 148         /*
 149          * Fault retry nuances, mmap_lock already relinquished by core mm
 150          */
 151         if (unlikely(fault & VM_FAULT_RETRY)) {
 152                 flags |= FAULT_FLAG_TRIED;
 153                 goto retry;
 154         }
 155
 156 bad_area:
 157         mmap_read_unlock(mm);
 158
 159 bad_area_nosemaphore:
 160         /*
 161          * Major/minor page fault accounting
 162          * (in case of retry we only land here once)
 163          */
 164         if (likely(!(fault & VM_FAULT_ERROR)))
 165                 /* Normal return path: fault Handled Gracefully */
 166                 return;
 167
 168         if (!user_mode(regs))
 169                 goto no_context;
 170
 171         if (fault & VM_FAULT_OOM) {
 172                 pagefault_out_of_memory();
 173                 return;
 174         }
 175
 176         if (fault & VM_FAULT_SIGBUS) {
 177                 sig = SIGBUS;
 178                 si_code = BUS_ADRERR;
 179         }
 180         else {
 181                 sig = SIGSEGV;
 182         }
 183
 184         tsk->thread.fault_address = address;
 185         force_sig_fault(sig, si_code, (void __user *)address);
 186         return;
 187
 188 no_context:
 189         if (fixup_exception(regs))
 190                 return;
 191
 192         die("Oops", regs, address);
 193 }