arch/frv/mm/fault.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/arch/frv/mm/fault.c
   4  *
   5  * Copyright (C) 2003 Red Hat, Inc. All Rights Reserved.
   6  * - Written by David Howells (dhowells@redhat.com)
   7  * - Derived from arch/m68knommu/mm/fault.c
   8  *   - Copyright (C) 1998  D. Jeff Dionne <jeff@lineo.ca>,
   9  *   - Copyright (C) 2000  Lineo, Inc.  (www.lineo.com)
  10  *
  11  *  Based on:
  12  *
  13  *  linux/arch/m68k/mm/fault.c
  14  *
  15  *  Copyright (C) 1995  Hamish Macdonald
  16  */
  17
  18 #include <linux/mman.h>
  19 #include <linux/mm.h>
  20 #include <linux/kernel.h>
  21 #include <linux/ptrace.h>
  22 #include <linux/hardirq.h>
  23 #include <linux/uaccess.h>
  24
  25 #include <asm/pgtable.h>
  26 #include <asm/gdb-stub.h>
  27
  28 /*****************************************************************************/
  29 /*
  30  * This routine handles page faults.  It determines the problem, and
  31  * then passes it off to one of the appropriate routines.
  32  */
  33 asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear0)
  34 {
  35         struct vm_area_struct *vma;
  36         struct mm_struct *mm;
  37         unsigned long _pme, lrai, lrad;
  38         unsigned long flags = 0;
  39         siginfo_t info;
  40         pgd_t *pge;
  41         pud_t *pue;
  42         pte_t *pte;
  43         int fault;
  44
  45 #if 0
  46         const char *atxc[16] = {
  47                 [0x0] = "mmu-miss", [0x8] = "multi-dat", [0x9] = "multi-sat",
  48                 [0xa] = "tlb-miss", [0xc] = "privilege", [0xd] = "write-prot",
  49         };
  50
  51         printk("do_page_fault(%d,%lx [%s],%lx)\n",
  52                datammu, esr0, atxc[esr0 >> 20 & 0xf], ear0);
  53 #endif
  54
  55         mm = current->mm;
  56
  57         /*
  58          * We fault-in kernel-space virtual memory on-demand. The
  59          * 'reference' page table is init_mm.pgd.
  60          *
  61          * NOTE! We MUST NOT take any locks for this case. We may
  62          * be in an interrupt or a critical region, and should
  63          * only copy the information from the master page table,
  64          * nothing more.
  65          *
  66          * This verifies that the fault happens in kernel space
  67          * and that the fault was a page not present (invalid) error
  68          */
  69         if (!user_mode(__frame) && (esr0 & ESR0_ATXC) == ESR0_ATXC_AMRTLB_MISS) {
  70                 if (ear0 >= VMALLOC_START && ear0 < VMALLOC_END)
  71                         goto kernel_pte_fault;
  72                 if (ear0 >= PKMAP_BASE && ear0 < PKMAP_END)
  73                         goto kernel_pte_fault;
  74         }
  75
  76         info.si_code = SEGV_MAPERR;
  77
  78         /*
  79          * If we're in an interrupt or have no user
  80          * context, we must not take the fault..
  81          */
  82         if (faulthandler_disabled() || !mm)
  83                 goto no_context;
  84
  85         if (user_mode(__frame))
  86                 flags |= FAULT_FLAG_USER;
  87
  88         down_read(&mm->mmap_sem);
  89
  90         vma = find_vma(mm, ear0);
  91         if (!vma)
  92                 goto bad_area;
  93         if (vma->vm_start <= ear0)
  94                 goto good_area;
  95         if (!(vma->vm_flags & VM_GROWSDOWN))
  96                 goto bad_area;
  97
  98         if (user_mode(__frame)) {
  99                 /*
 100                  * accessing the stack below %esp is always a bug.
 101                  * The "+ 32" is there due to some instructions (like
 102                  * pusha) doing post-decrement on the stack and that
 103                  * doesn't show up until later..
 104                  */
 105                 if ((ear0 & PAGE_MASK) + 2 * PAGE_SIZE < __frame->sp) {
 106 #if 0
 107                         printk("[%d] ### Access below stack @%lx (sp=%lx)\n",
 108                                current->pid, ear0, __frame->sp);
 109                         show_registers(__frame);
 110                         printk("[%d] ### Code: [%08lx] %02x %02x %02x %02x %02x %02x %02x %02x\n",
 111                                current->pid,
 112                                __frame->pc,
 113                                ((u8*)__frame->pc)[0],
 114                                ((u8*)__frame->pc)[1],
 115                                ((u8*)__frame->pc)[2],
 116                                ((u8*)__frame->pc)[3],
 117                                ((u8*)__frame->pc)[4],
 118                                ((u8*)__frame->pc)[5],
 119                                ((u8*)__frame->pc)[6],
 120                                ((u8*)__frame->pc)[7]
 121                                );
 122 #endif
 123                         goto bad_area;
 124                 }
 125         }
 126
 127         if (expand_stack(vma, ear0))
 128                 goto bad_area;
 129
 130 /*
 131  * Ok, we have a good vm_area for this memory access, so
 132  * we can handle it..
 133  */
 134  good_area:
 135         info.si_code = SEGV_ACCERR;
 136         switch (esr0 & ESR0_ATXC) {
 137         default:
 138                 /* handle write to write protected page */
 139         case ESR0_ATXC_WP_EXCEP:
 140 #ifdef TEST_VERIFY_AREA
 141                 if (!(user_mode(__frame)))
 142                         printk("WP fault at %08lx\n", __frame->pc);
 143 #endif
 144                 if (!(vma->vm_flags & VM_WRITE))
 145                         goto bad_area;
 146                 flags |= FAULT_FLAG_WRITE;
 147                 break;
 148
 149                  /* handle read from protected page */
 150         case ESR0_ATXC_PRIV_EXCEP:
 151                 goto bad_area;
 152
 153                  /* handle read, write or exec on absent page
 154                   * - can't support write without permitting read
 155                   * - don't support execute without permitting read and vice-versa
 156                   */
 157         case ESR0_ATXC_AMRTLB_MISS:
 158                 if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
 159                         goto bad_area;
 160                 break;
 161         }
 162
 163         /*
 164          * If for any reason at all we couldn't handle the fault,
 165          * make sure we exit gracefully rather than endlessly redo
 166          * the fault.
 167          */
 168         fault = handle_mm_fault(vma, ear0, flags);
 169         if (unlikely(fault & VM_FAULT_ERROR)) {
 170                 if (fault & VM_FAULT_OOM)
 171                         goto out_of_memory;
 172                 else if (fault & VM_FAULT_SIGSEGV)
 173                         goto bad_area;
 174                 else if (fault & VM_FAULT_SIGBUS)
 175                         goto do_sigbus;
 176                 BUG();
 177         }
 178         if (fault & VM_FAULT_MAJOR)
 179                 current->maj_flt++;
 180         else
 181                 current->min_flt++;
 182
 183         up_read(&mm->mmap_sem);
 184         return;
 185
 186 /*
 187  * Something tried to access memory that isn't in our memory map..
 188  * Fix it, but check if it's kernel or user first..
 189  */
 190  bad_area:
 191         up_read(&mm->mmap_sem);
 192
 193         /* User mode accesses just cause a SIGSEGV */
 194         if (user_mode(__frame)) {
 195                 info.si_signo = SIGSEGV;
 196                 info.si_errno = 0;
 197                 /* info.si_code has been set above */
 198                 info.si_addr = (void *) ear0;
 199                 force_sig_info(SIGSEGV, &info, current);
 200                 return;
 201         }
 202
 203  no_context:
 204         /* are we prepared to handle this kernel fault? */
 205         if (fixup_exception(__frame))
 206                 return;
 207
 208 /*
 209  * Oops. The kernel tried to access some bad page. We'll have to
 210  * terminate things with extreme prejudice.
 211  */
 212
 213         bust_spinlocks(1);
 214
 215         if (ear0 < PAGE_SIZE)
 216                 printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
 217         else
 218                 printk(KERN_ALERT "Unable to handle kernel paging request");
 219         printk(" at virtual addr %08lx\n", ear0);
 220         printk("  PC  : %08lx\n", __frame->pc);
 221         printk("  EXC : esr0=%08lx ear0=%08lx\n", esr0, ear0);
 222
 223         asm("lrai %1,%0,#1,#0,#0" : "=&r"(lrai) : "r"(ear0));
 224         asm("lrad %1,%0,#1,#0,#0" : "=&r"(lrad) : "r"(ear0));
 225
 226         printk(KERN_ALERT "  LRAI: %08lx\n", lrai);
 227         printk(KERN_ALERT "  LRAD: %08lx\n", lrad);
 228
 229         __break_hijack_kernel_event();
 230
 231         pge = pgd_offset(current->mm, ear0);
 232         pue = pud_offset(pge, ear0);
 233         _pme = pue->pue[0].ste[0];
 234
 235         printk(KERN_ALERT "  PGE : %8p { PME %08lx }\n", pge, _pme);
 236
 237         if (_pme & xAMPRx_V) {
 238                 unsigned long dampr, damlr, val;
 239
 240                 asm volatile("movsg dampr2,%0 ! movgs %2,dampr2 ! movsg damlr2,%1"
 241                              : "=&r"(dampr), "=r"(damlr)
 242                              : "r" (_pme | xAMPRx_L|xAMPRx_SS_16Kb|xAMPRx_S|xAMPRx_C|xAMPRx_V)
 243                              );
 244
 245                 pte = (pte_t *) damlr + __pte_index(ear0);
 246                 val = pte_val(*pte);
 247
 248                 asm volatile("movgs %0,dampr2" :: "r" (dampr));
 249
 250                 printk(KERN_ALERT "  PTE : %8p { %08lx }\n", pte, val);
 251         }
 252
 253         die_if_kernel("Oops\n");
 254         do_exit(SIGKILL);
 255
 256 /*
 257  * We ran out of memory, or some other thing happened to us that made
 258  * us unable to handle the page fault gracefully.
 259  */
 260  out_of_memory:
 261         up_read(&mm->mmap_sem);
 262         if (!user_mode(__frame))
 263                 goto no_context;
 264         pagefault_out_of_memory();
 265         return;
 266
 267  do_sigbus:
 268         up_read(&mm->mmap_sem);
 269
 270         /*
 271          * Send a sigbus, regardless of whether we were in kernel
 272          * or user mode.
 273          */
 274         info.si_signo = SIGBUS;
 275         info.si_errno = 0;
 276         info.si_code = BUS_ADRERR;
 277         info.si_addr = (void *) ear0;
 278         force_sig_info(SIGBUS, &info, current);
 279
 280         /* Kernel mode? Handle exceptions or die */
 281         if (!user_mode(__frame))
 282                 goto no_context;
 283         return;
 284
 285 /*
 286  * The fault was caused by a kernel PTE (such as installed by vmalloc or kmap)
 287  */
 288  kernel_pte_fault:
 289         {
 290                 /*
 291                  * Synchronize this task's top level page-table
 292                  * with the 'reference' page table.
 293                  *
 294                  * Do _not_ use "tsk" here. We might be inside
 295                  * an interrupt in the middle of a task switch..
 296                  */
 297                 int index = pgd_index(ear0);
 298                 pgd_t *pgd, *pgd_k;
 299                 pud_t *pud, *pud_k;
 300                 pmd_t *pmd, *pmd_k;
 301                 pte_t *pte_k;
 302
 303                 pgd = (pgd_t *) __get_TTBR();
 304                 pgd = (pgd_t *)__va(pgd) + index;
 305                 pgd_k = ((pgd_t *)(init_mm.pgd)) + index;
 306
 307                 if (!pgd_present(*pgd_k))
 308                         goto no_context;
 309                 //set_pgd(pgd, *pgd_k); /////// gcc ICE's on this line
 310
 311                 pud_k = pud_offset(pgd_k, ear0);
 312                 if (!pud_present(*pud_k))
 313                         goto no_context;
 314
 315                 pmd_k = pmd_offset(pud_k, ear0);
 316                 if (!pmd_present(*pmd_k))
 317                         goto no_context;
 318
 319                 pud = pud_offset(pgd, ear0);
 320                 pmd = pmd_offset(pud, ear0);
 321                 set_pmd(pmd, *pmd_k);
 322
 323                 pte_k = pte_offset_kernel(pmd_k, ear0);
 324                 if (!pte_present(*pte_k))
 325                         goto no_context;
 326                 return;
 327         }
 328 } /* end do_page_fault() */