arch/metag/mm/fault.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  Meta page fault handling.
   4  *
   5  *  Copyright (C) 2005-2012 Imagination Technologies Ltd.
   6  */
   7
   8 #include <linux/mman.h>
   9 #include <linux/mm.h>
  10 #include <linux/kernel.h>
  11 #include <linux/ptrace.h>
  12 #include <linux/sched/debug.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/uaccess.h>
  15
  16 #include <asm/tlbflush.h>
  17 #include <asm/mmu.h>
  18 #include <asm/traps.h>
  19
  20 /* Clear any pending catch buffer state. */
  21 static void clear_cbuf_entry(struct pt_regs *regs, unsigned long addr,
  22                              unsigned int trapno)
  23 {
  24         PTBICTXEXTCB0 cbuf = regs->extcb0;
  25
  26         switch (trapno) {
  27                 /* Instruction fetch faults leave no catch buffer state. */
  28         case TBIXXF_SIGNUM_IGF:
  29         case TBIXXF_SIGNUM_IPF:
  30                 return;
  31         default:
  32                 if (cbuf[0].CBAddr == addr) {
  33                         cbuf[0].CBAddr = 0;
  34                         cbuf[0].CBFlags &= ~TXCATCH0_FAULT_BITS;
  35
  36                         /* And, as this is the ONLY catch entry, we
  37                          * need to clear the cbuf bit from the context!
  38                          */
  39                         regs->ctx.SaveMask &= ~(TBICTX_CBUF_BIT |
  40                                                 TBICTX_XCBF_BIT);
  41
  42                         return;
  43                 }
  44                 pr_err("Failed to clear cbuf entry!\n");
  45         }
  46 }
  47
  48 int show_unhandled_signals = 1;
  49
  50 int do_page_fault(struct pt_regs *regs, unsigned long address,
  51                   unsigned int write_access, unsigned int trapno)
  52 {
  53         struct task_struct *tsk;
  54         struct mm_struct *mm;
  55         struct vm_area_struct *vma, *prev_vma;
  56         siginfo_t info;
  57         int fault;
  58         unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
  59
  60         tsk = current;
  61
  62         if ((address >= VMALLOC_START) && (address < VMALLOC_END)) {
  63                 /*
  64                  * Synchronize this task's top level page-table
  65                  * with the 'reference' page table.
  66                  *
  67                  * Do _not_ use "tsk" here. We might be inside
  68                  * an interrupt in the middle of a task switch..
  69                  */
  70                 int offset = pgd_index(address);
  71                 pgd_t *pgd, *pgd_k;
  72                 pud_t *pud, *pud_k;
  73                 pmd_t *pmd, *pmd_k;
  74                 pte_t *pte_k;
  75
  76                 pgd = ((pgd_t *)mmu_get_base()) + offset;
  77                 pgd_k = swapper_pg_dir + offset;
  78
  79                 /* This will never happen with the folded page table. */
  80                 if (!pgd_present(*pgd)) {
  81                         if (!pgd_present(*pgd_k))
  82                                 goto bad_area_nosemaphore;
  83                         set_pgd(pgd, *pgd_k);
  84                         return 0;
  85                 }
  86
  87                 pud = pud_offset(pgd, address);
  88                 pud_k = pud_offset(pgd_k, address);
  89                 if (!pud_present(*pud_k))
  90                         goto bad_area_nosemaphore;
  91                 set_pud(pud, *pud_k);
  92
  93                 pmd = pmd_offset(pud, address);
  94                 pmd_k = pmd_offset(pud_k, address);
  95                 if (!pmd_present(*pmd_k))
  96                         goto bad_area_nosemaphore;
  97                 set_pmd(pmd, *pmd_k);
  98
  99                 pte_k = pte_offset_kernel(pmd_k, address);
 100                 if (!pte_present(*pte_k))
 101                         goto bad_area_nosemaphore;
 102
 103                 /* May only be needed on Chorus2 */
 104                 flush_tlb_all();
 105                 return 0;
 106         }
 107
 108         mm = tsk->mm;
 109
 110         if (faulthandler_disabled() || !mm)
 111                 goto no_context;
 112
 113         if (user_mode(regs))
 114                 flags |= FAULT_FLAG_USER;
 115 retry:
 116         down_read(&mm->mmap_sem);
 117
 118         vma = find_vma_prev(mm, address, &prev_vma);
 119
 120         if (!vma || address < vma->vm_start)
 121                 goto check_expansion;
 122
 123 good_area:
 124         if (write_access) {
 125                 if (!(vma->vm_flags & VM_WRITE))
 126                         goto bad_area;
 127                 flags |= FAULT_FLAG_WRITE;
 128         } else {
 129                 if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
 130                         goto bad_area;
 131         }
 132
 133         /*
 134          * If for any reason at all we couldn't handle the fault,
 135          * make sure we exit gracefully rather than endlessly redo
 136          * the fault.
 137          */
 138         fault = handle_mm_fault(vma, address, flags);
 139
 140         if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 141                 return 0;
 142
 143         if (unlikely(fault & VM_FAULT_ERROR)) {
 144                 if (fault & VM_FAULT_OOM)
 145                         goto out_of_memory;
 146                 else if (fault & VM_FAULT_SIGSEGV)
 147                         goto bad_area;
 148                 else if (fault & VM_FAULT_SIGBUS)
 149                         goto do_sigbus;
 150                 BUG();
 151         }
 152         if (flags & FAULT_FLAG_ALLOW_RETRY) {
 153                 if (fault & VM_FAULT_MAJOR)
 154                         tsk->maj_flt++;
 155                 else
 156                         tsk->min_flt++;
 157                 if (fault & VM_FAULT_RETRY) {
 158                         flags &= ~FAULT_FLAG_ALLOW_RETRY;
 159                         flags |= FAULT_FLAG_TRIED;
 160
 161                         /*
 162                          * No need to up_read(&mm->mmap_sem) as we would
 163                          * have already released it in __lock_page_or_retry
 164                          * in mm/filemap.c.
 165                          */
 166
 167                         goto retry;
 168                 }
 169         }
 170
 171         up_read(&mm->mmap_sem);
 172         return 0;
 173
 174 check_expansion:
 175         vma = prev_vma;
 176         if (vma && (expand_stack(vma, address) == 0))
 177                 goto good_area;
 178
 179 bad_area:
 180         up_read(&mm->mmap_sem);
 181
 182 bad_area_nosemaphore:
 183         if (user_mode(regs)) {
 184                 info.si_signo = SIGSEGV;
 185                 info.si_errno = 0;
 186                 info.si_code = SEGV_MAPERR;
 187                 info.si_addr = (__force void __user *)address;
 188                 info.si_trapno = trapno;
 189
 190                 if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
 191                     printk_ratelimit()) {
 192                         printk("%s%s[%d]: segfault at %lx pc %08x sp %08x write %d trap %#x (%s)",
 193                                task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
 194                                tsk->comm, task_pid_nr(tsk), address,
 195                                regs->ctx.CurrPC, regs->ctx.AX[0].U0,
 196                                write_access, trapno, trap_name(trapno));
 197                         print_vma_addr(" in ", regs->ctx.CurrPC);
 198                         print_vma_addr(" rtp in ", regs->ctx.DX[4].U1);
 199                         printk("\n");
 200                         show_regs(regs);
 201                 }
 202                 force_sig_info(SIGSEGV, &info, tsk);
 203                 return 1;
 204         }
 205         goto no_context;
 206
 207 do_sigbus:
 208         up_read(&mm->mmap_sem);
 209
 210         /*
 211          * Send a sigbus, regardless of whether we were in kernel
 212          * or user mode.
 213          */
 214         info.si_signo = SIGBUS;
 215         info.si_errno = 0;
 216         info.si_code = BUS_ADRERR;
 217         info.si_addr = (__force void __user *)address;
 218         info.si_trapno = trapno;
 219         force_sig_info(SIGBUS, &info, tsk);
 220
 221         /* Kernel mode? Handle exceptions or die */
 222         if (!user_mode(regs))
 223                 goto no_context;
 224
 225         return 1;
 226
 227         /*
 228          * We ran out of memory, or some other thing happened to us that made
 229          * us unable to handle the page fault gracefully.
 230          */
 231 out_of_memory:
 232         up_read(&mm->mmap_sem);
 233         if (user_mode(regs)) {
 234                 pagefault_out_of_memory();
 235                 return 1;
 236         }
 237
 238 no_context:
 239         /* Are we prepared to handle this kernel fault?  */
 240         if (fixup_exception(regs)) {
 241                 clear_cbuf_entry(regs, address, trapno);
 242                 return 1;
 243         }
 244
 245         die("Oops", regs, (write_access << 15) | trapno, address);
 246         do_exit(SIGKILL);
 247 }