arch/csky/mm/fault.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 // Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
   3
   4 #include <linux/signal.h>
   5 #include <linux/module.h>
   6 #include <linux/sched.h>
   7 #include <linux/interrupt.h>
   8 #include <linux/kernel.h>
   9 #include <linux/errno.h>
  10 #include <linux/string.h>
  11 #include <linux/types.h>
  12 #include <linux/ptrace.h>
  13 #include <linux/mman.h>
  14 #include <linux/mm.h>
  15 #include <linux/smp.h>
  16 #include <linux/version.h>
  17 #include <linux/vt_kern.h>
  18 #include <linux/extable.h>
  19 #include <linux/uaccess.h>
  20 #include <linux/perf_event.h>
  21 #include <linux/kprobes.h>
  22
  23 #include <asm/hardirq.h>
  24 #include <asm/mmu_context.h>
  25 #include <asm/traps.h>
  26 #include <asm/page.h>
  27
  28 int fixup_exception(struct pt_regs *regs)
  29 {
  30         const struct exception_table_entry *fixup;
  31
  32         fixup = search_exception_tables(instruction_pointer(regs));
  33         if (fixup) {
  34                 regs->pc = fixup->nextinsn;
  35
  36                 return 1;
  37         }
  38
  39         return 0;
  40 }
  41
  42 /*
  43  * This routine handles page faults. It determines the address,
  44  * and the problem, and then passes it off to one of the appropriate
  45  * routines.
  46  */
  47 asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
  48                               unsigned long mmu_meh)
  49 {
  50         struct vm_area_struct *vma = NULL;
  51         struct task_struct *tsk = current;
  52         struct mm_struct *mm = tsk->mm;
  53         int si_code;
  54         int fault;
  55         unsigned long address = mmu_meh & PAGE_MASK;
  56
  57         if (kprobe_page_fault(regs, tsk->thread.trap_no))
  58                 return;
  59
  60         si_code = SEGV_MAPERR;
  61
  62 #ifndef CONFIG_CPU_HAS_TLBI
  63         /*
  64          * We fault-in kernel-space virtual memory on-demand. The
  65          * 'reference' page table is init_mm.pgd.
  66          *
  67          * NOTE! We MUST NOT take any locks for this case. We may
  68          * be in an interrupt or a critical region, and should
  69          * only copy the information from the master page table,
  70          * nothing more.
  71          */
  72         if (unlikely(address >= VMALLOC_START) &&
  73             unlikely(address <= VMALLOC_END)) {
  74                 /*
  75                  * Synchronize this task's top level page-table
  76                  * with the 'reference' page table.
  77                  *
  78                  * Do _not_ use "tsk" here. We might be inside
  79                  * an interrupt in the middle of a task switch..
  80                  */
  81                 int offset = pgd_index(address);
  82                 pgd_t *pgd, *pgd_k;
  83                 pud_t *pud, *pud_k;
  84                 pmd_t *pmd, *pmd_k;
  85                 pte_t *pte_k;
  86
  87                 unsigned long pgd_base;
  88
  89                 pgd_base = (unsigned long)__va(get_pgd());
  90                 pgd = (pgd_t *)pgd_base + offset;
  91                 pgd_k = init_mm.pgd + offset;
  92
  93                 if (!pgd_present(*pgd_k))
  94                         goto no_context;
  95                 set_pgd(pgd, *pgd_k);
  96
  97                 pud = (pud_t *)pgd;
  98                 pud_k = (pud_t *)pgd_k;
  99                 if (!pud_present(*pud_k))
 100                         goto no_context;
 101
 102                 pmd = pmd_offset(pud, address);
 103                 pmd_k = pmd_offset(pud_k, address);
 104                 if (!pmd_present(*pmd_k))
 105                         goto no_context;
 106                 set_pmd(pmd, *pmd_k);
 107
 108                 pte_k = pte_offset_kernel(pmd_k, address);
 109                 if (!pte_present(*pte_k))
 110                         goto no_context;
 111                 return;
 112         }
 113 #endif
 114
 115         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
 116         /*
 117          * If we're in an interrupt or have no user
 118          * context, we must not take the fault..
 119          */
 120         if (in_atomic() || !mm)
 121                 goto bad_area_nosemaphore;
 122
 123         mmap_read_lock(mm);
 124         vma = find_vma(mm, address);
 125         if (!vma)
 126                 goto bad_area;
 127         if (vma->vm_start <= address)
 128                 goto good_area;
 129         if (!(vma->vm_flags & VM_GROWSDOWN))
 130                 goto bad_area;
 131         if (expand_stack(vma, address))
 132                 goto bad_area;
 133         /*
 134          * Ok, we have a good vm_area for this memory access, so
 135          * we can handle it..
 136          */
 137 good_area:
 138         si_code = SEGV_ACCERR;
 139
 140         if (write) {
 141                 if (!(vma->vm_flags & VM_WRITE))
 142                         goto bad_area;
 143         } else {
 144                 if (unlikely(!vma_is_accessible(vma)))
 145                         goto bad_area;
 146         }
 147
 148         /*
 149          * If for any reason at all we couldn't handle the fault,
 150          * make sure we exit gracefully rather than endlessly redo
 151          * the fault.
 152          */
 153         fault = handle_mm_fault(vma, address, write ? FAULT_FLAG_WRITE : 0,
 154                                 regs);
 155         if (unlikely(fault & VM_FAULT_ERROR)) {
 156                 if (fault & VM_FAULT_OOM)
 157                         goto out_of_memory;
 158                 else if (fault & VM_FAULT_SIGBUS)
 159                         goto do_sigbus;
 160                 else if (fault & VM_FAULT_SIGSEGV)
 161                         goto bad_area;
 162                 BUG();
 163         }
 164         mmap_read_unlock(mm);
 165         return;
 166
 167         /*
 168          * Something tried to access memory that isn't in our memory map..
 169          * Fix it, but check if it's kernel or user first..
 170          */
 171 bad_area:
 172         mmap_read_unlock(mm);
 173
 174 bad_area_nosemaphore:
 175         /* User mode accesses just cause a SIGSEGV */
 176         if (user_mode(regs)) {
 177                 tsk->thread.trap_no = trap_no(regs);
 178                 force_sig_fault(SIGSEGV, si_code, (void __user *)address);
 179                 return;
 180         }
 181
 182 no_context:
 183         tsk->thread.trap_no = trap_no(regs);
 184
 185         /* Are we prepared to handle this kernel fault? */
 186         if (fixup_exception(regs))
 187                 return;
 188
 189         /*
 190          * Oops. The kernel tried to access some bad page. We'll have to
 191          * terminate things with extreme prejudice.
 192          */
 193         bust_spinlocks(1);
 194         pr_alert("Unable to handle kernel paging request at virtual "
 195                  "address 0x%08lx, pc: 0x%08lx\n", address, regs->pc);
 196         die(regs, "Oops");
 197
 198 out_of_memory:
 199         tsk->thread.trap_no = trap_no(regs);
 200
 201         /*
 202          * We ran out of memory, call the OOM killer, and return the userspace
 203          * (which will retry the fault, or kill us if we got oom-killed).
 204          */
 205         pagefault_out_of_memory();
 206         return;
 207
 208 do_sigbus:
 209         tsk->thread.trap_no = trap_no(regs);
 210
 211         mmap_read_unlock(mm);
 212
 213         /* Kernel mode? Handle exceptions or die */
 214         if (!user_mode(regs))
 215                 goto no_context;
 216
 217         force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address);
 218 }