![Kirill A. Shutemov](/assets/img/avatar_default.png)
We always have vma->vm_mm around. Link: http://lkml.kernel.org/r/1466021202-61880-8-git-send-email-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
221 lines
5.3 KiB
C
221 lines
5.3 KiB
C
/*
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* linux/arch/m68k/mm/fault.c
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*
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* Copyright (C) 1995 Hamish Macdonald
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*/
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#include <linux/mman.h>
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#include <linux/mm.h>
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#include <linux/kernel.h>
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#include <linux/ptrace.h>
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#include <linux/interrupt.h>
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#include <linux/module.h>
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#include <linux/uaccess.h>
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#include <asm/setup.h>
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#include <asm/traps.h>
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#include <asm/pgalloc.h>
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extern void die_if_kernel(char *, struct pt_regs *, long);
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int send_fault_sig(struct pt_regs *regs)
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{
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siginfo_t siginfo = { 0, 0, 0, };
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siginfo.si_signo = current->thread.signo;
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siginfo.si_code = current->thread.code;
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siginfo.si_addr = (void *)current->thread.faddr;
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pr_debug("send_fault_sig: %p,%d,%d\n", siginfo.si_addr,
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siginfo.si_signo, siginfo.si_code);
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if (user_mode(regs)) {
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force_sig_info(siginfo.si_signo,
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&siginfo, current);
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} else {
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if (handle_kernel_fault(regs))
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return -1;
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//if (siginfo.si_signo == SIGBUS)
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// force_sig_info(siginfo.si_signo,
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// &siginfo, current);
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/*
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* Oops. The kernel tried to access some bad page. We'll have to
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* terminate things with extreme prejudice.
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*/
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if ((unsigned long)siginfo.si_addr < PAGE_SIZE)
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pr_alert("Unable to handle kernel NULL pointer dereference");
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else
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pr_alert("Unable to handle kernel access");
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pr_cont(" at virtual address %p\n", siginfo.si_addr);
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die_if_kernel("Oops", regs, 0 /*error_code*/);
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do_exit(SIGKILL);
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}
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return 1;
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}
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/*
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* This routine handles page faults. It determines the problem, and
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* then passes it off to one of the appropriate routines.
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*
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* error_code:
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* bit 0 == 0 means no page found, 1 means protection fault
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* bit 1 == 0 means read, 1 means write
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*
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* If this routine detects a bad access, it returns 1, otherwise it
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* returns 0.
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*/
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int do_page_fault(struct pt_regs *regs, unsigned long address,
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unsigned long error_code)
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{
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struct mm_struct *mm = current->mm;
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struct vm_area_struct * vma;
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int fault;
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unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
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pr_debug("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n",
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regs->sr, regs->pc, address, error_code, mm ? mm->pgd : NULL);
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/*
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* If we're in an interrupt or have no user
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* context, we must not take the fault..
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*/
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if (faulthandler_disabled() || !mm)
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goto no_context;
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if (user_mode(regs))
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flags |= FAULT_FLAG_USER;
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retry:
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down_read(&mm->mmap_sem);
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vma = find_vma(mm, address);
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if (!vma)
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goto map_err;
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if (vma->vm_flags & VM_IO)
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goto acc_err;
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if (vma->vm_start <= address)
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goto good_area;
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if (!(vma->vm_flags & VM_GROWSDOWN))
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goto map_err;
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if (user_mode(regs)) {
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/* Accessing the stack below usp is always a bug. The
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"+ 256" is there due to some instructions doing
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pre-decrement on the stack and that doesn't show up
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until later. */
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if (address + 256 < rdusp())
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goto map_err;
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}
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if (expand_stack(vma, address))
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goto map_err;
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/*
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* Ok, we have a good vm_area for this memory access, so
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* we can handle it..
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*/
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good_area:
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pr_debug("do_page_fault: good_area\n");
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switch (error_code & 3) {
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default: /* 3: write, present */
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/* fall through */
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case 2: /* write, not present */
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if (!(vma->vm_flags & VM_WRITE))
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goto acc_err;
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flags |= FAULT_FLAG_WRITE;
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break;
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case 1: /* read, present */
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goto acc_err;
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case 0: /* read, not present */
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if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
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goto acc_err;
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}
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/*
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* If for any reason at all we couldn't handle the fault,
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* make sure we exit gracefully rather than endlessly redo
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* the fault.
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*/
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fault = handle_mm_fault(vma, address, flags);
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pr_debug("handle_mm_fault returns %d\n", fault);
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if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
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return 0;
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if (unlikely(fault & VM_FAULT_ERROR)) {
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if (fault & VM_FAULT_OOM)
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goto out_of_memory;
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else if (fault & VM_FAULT_SIGSEGV)
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goto map_err;
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else if (fault & VM_FAULT_SIGBUS)
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goto bus_err;
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BUG();
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}
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/*
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* Major/minor page fault accounting is only done on the
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* initial attempt. If we go through a retry, it is extremely
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* likely that the page will be found in page cache at that point.
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*/
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if (flags & FAULT_FLAG_ALLOW_RETRY) {
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if (fault & VM_FAULT_MAJOR)
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current->maj_flt++;
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else
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current->min_flt++;
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if (fault & VM_FAULT_RETRY) {
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/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
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* of starvation. */
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags |= FAULT_FLAG_TRIED;
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/*
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* No need to up_read(&mm->mmap_sem) as we would
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* have already released it in __lock_page_or_retry
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* in mm/filemap.c.
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*/
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goto retry;
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}
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}
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up_read(&mm->mmap_sem);
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return 0;
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/*
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* We ran out of memory, or some other thing happened to us that made
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* us unable to handle the page fault gracefully.
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*/
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out_of_memory:
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up_read(&mm->mmap_sem);
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if (!user_mode(regs))
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goto no_context;
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pagefault_out_of_memory();
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return 0;
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no_context:
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current->thread.signo = SIGBUS;
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current->thread.faddr = address;
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return send_fault_sig(regs);
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bus_err:
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current->thread.signo = SIGBUS;
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current->thread.code = BUS_ADRERR;
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current->thread.faddr = address;
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goto send_sig;
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map_err:
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current->thread.signo = SIGSEGV;
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current->thread.code = SEGV_MAPERR;
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current->thread.faddr = address;
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goto send_sig;
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acc_err:
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current->thread.signo = SIGSEGV;
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current->thread.code = SEGV_ACCERR;
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current->thread.faddr = address;
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send_sig:
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up_read(&mm->mmap_sem);
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return send_fault_sig(regs);
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}
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