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- /*
- * MMU fault handling support.
- *
- * Copyright (C) 1998-2002 Hewlett-Packard Co
- * David Mosberger-Tang <davidm@hpl.hp.com>
- */
- #include <linux/sched.h>
- #include <linux/kernel.h>
- #include <linux/mm.h>
- #include <linux/interrupt.h>
- #include <linux/kprobes.h>
- #include <linux/kdebug.h>
- #include <linux/prefetch.h>
- #include <linux/uaccess.h>
- #include <asm/pgtable.h>
- #include <asm/processor.h>
- extern int die(char *, struct pt_regs *, long);
- #ifdef CONFIG_KPROBES
- static inline int notify_page_fault(struct pt_regs *regs, int trap)
- {
- int ret = 0;
- if (!user_mode(regs)) {
- /* kprobe_running() needs smp_processor_id() */
- preempt_disable();
- if (kprobe_running() && kprobe_fault_handler(regs, trap))
- ret = 1;
- preempt_enable();
- }
- return ret;
- }
- #else
- static inline int notify_page_fault(struct pt_regs *regs, int trap)
- {
- return 0;
- }
- #endif
- /*
- * Return TRUE if ADDRESS points at a page in the kernel's mapped segment
- * (inside region 5, on ia64) and that page is present.
- */
- static int
- mapped_kernel_page_is_present (unsigned long address)
- {
- pgd_t *pgd;
- pud_t *pud;
- pmd_t *pmd;
- pte_t *ptep, pte;
- pgd = pgd_offset_k(address);
- if (pgd_none(*pgd) || pgd_bad(*pgd))
- return 0;
- pud = pud_offset(pgd, address);
- if (pud_none(*pud) || pud_bad(*pud))
- return 0;
- pmd = pmd_offset(pud, address);
- if (pmd_none(*pmd) || pmd_bad(*pmd))
- return 0;
- ptep = pte_offset_kernel(pmd, address);
- if (!ptep)
- return 0;
- pte = *ptep;
- return pte_present(pte);
- }
- # define VM_READ_BIT 0
- # define VM_WRITE_BIT 1
- # define VM_EXEC_BIT 2
- void __kprobes
- ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *regs)
- {
- int signal = SIGSEGV, code = SEGV_MAPERR;
- struct vm_area_struct *vma, *prev_vma;
- struct mm_struct *mm = current->mm;
- struct siginfo si;
- unsigned long mask;
- int fault;
- unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
- mask = ((((isr >> IA64_ISR_X_BIT) & 1UL) << VM_EXEC_BIT)
- | (((isr >> IA64_ISR_W_BIT) & 1UL) << VM_WRITE_BIT));
- /* mmap_sem is performance critical.... */
- prefetchw(&mm->mmap_sem);
- /*
- * If we're in an interrupt or have no user context, we must not take the fault..
- */
- if (faulthandler_disabled() || !mm)
- goto no_context;
- #ifdef CONFIG_VIRTUAL_MEM_MAP
- /*
- * If fault is in region 5 and we are in the kernel, we may already
- * have the mmap_sem (pfn_valid macro is called during mmap). There
- * is no vma for region 5 addr's anyway, so skip getting the semaphore
- * and go directly to the exception handling code.
- */
- if ((REGION_NUMBER(address) == 5) && !user_mode(regs))
- goto bad_area_no_up;
- #endif
- /*
- * This is to handle the kprobes on user space access instructions
- */
- if (notify_page_fault(regs, TRAP_BRKPT))
- return;
- if (user_mode(regs))
- flags |= FAULT_FLAG_USER;
- if (mask & VM_WRITE)
- flags |= FAULT_FLAG_WRITE;
- retry:
- down_read(&mm->mmap_sem);
- vma = find_vma_prev(mm, address, &prev_vma);
- if (!vma && !prev_vma )
- goto bad_area;
- /*
- * find_vma_prev() returns vma such that address < vma->vm_end or NULL
- *
- * May find no vma, but could be that the last vm area is the
- * register backing store that needs to expand upwards, in
- * this case vma will be null, but prev_vma will ne non-null
- */
- if (( !vma && prev_vma ) || (address < vma->vm_start) )
- goto check_expansion;
- good_area:
- code = SEGV_ACCERR;
- /* OK, we've got a good vm_area for this memory area. Check the access permissions: */
- # if (((1 << VM_READ_BIT) != VM_READ || (1 << VM_WRITE_BIT) != VM_WRITE) \
- || (1 << VM_EXEC_BIT) != VM_EXEC)
- # error File is out of sync with <linux/mm.h>. Please update.
- # endif
- if (((isr >> IA64_ISR_R_BIT) & 1UL) && (!(vma->vm_flags & (VM_READ | VM_WRITE))))
- goto bad_area;
- if ((vma->vm_flags & mask) != mask)
- goto bad_area;
- /*
- * If for any reason at all we couldn't handle the fault, make
- * sure we exit gracefully rather than endlessly redo the
- * fault.
- */
- fault = handle_mm_fault(mm, vma, address, flags);
- if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
- return;
- if (unlikely(fault & VM_FAULT_ERROR)) {
- /*
- * We ran out of memory, or some other thing happened
- * to us that made us unable to handle the page fault
- * gracefully.
- */
- if (fault & VM_FAULT_OOM) {
- goto out_of_memory;
- } else if (fault & VM_FAULT_SIGSEGV) {
- goto bad_area;
- } else if (fault & VM_FAULT_SIGBUS) {
- signal = SIGBUS;
- goto bad_area;
- }
- BUG();
- }
- if (flags & FAULT_FLAG_ALLOW_RETRY) {
- if (fault & VM_FAULT_MAJOR)
- current->maj_flt++;
- else
- current->min_flt++;
- if (fault & VM_FAULT_RETRY) {
- flags &= ~FAULT_FLAG_ALLOW_RETRY;
- flags |= FAULT_FLAG_TRIED;
- /* No need to up_read(&mm->mmap_sem) as we would
- * have already released it in __lock_page_or_retry
- * in mm/filemap.c.
- */
- goto retry;
- }
- }
- up_read(&mm->mmap_sem);
- return;
- check_expansion:
- if (!(prev_vma && (prev_vma->vm_flags & VM_GROWSUP) && (address == prev_vma->vm_end))) {
- if (!vma)
- goto bad_area;
- if (!(vma->vm_flags & VM_GROWSDOWN))
- goto bad_area;
- if (REGION_NUMBER(address) != REGION_NUMBER(vma->vm_start)
- || REGION_OFFSET(address) >= RGN_MAP_LIMIT)
- goto bad_area;
- if (expand_stack(vma, address))
- goto bad_area;
- } else {
- vma = prev_vma;
- if (REGION_NUMBER(address) != REGION_NUMBER(vma->vm_start)
- || REGION_OFFSET(address) >= RGN_MAP_LIMIT)
- goto bad_area;
- /*
- * Since the register backing store is accessed sequentially,
- * we disallow growing it by more than a page at a time.
- */
- if (address > vma->vm_end + PAGE_SIZE - sizeof(long))
- goto bad_area;
- if (expand_upwards(vma, address))
- goto bad_area;
- }
- goto good_area;
- bad_area:
- up_read(&mm->mmap_sem);
- #ifdef CONFIG_VIRTUAL_MEM_MAP
- bad_area_no_up:
- #endif
- if ((isr & IA64_ISR_SP)
- || ((isr & IA64_ISR_NA) && (isr & IA64_ISR_CODE_MASK) == IA64_ISR_CODE_LFETCH))
- {
- /*
- * This fault was due to a speculative load or lfetch.fault, set the "ed"
- * bit in the psr to ensure forward progress. (Target register will get a
- * NaT for ld.s, lfetch will be canceled.)
- */
- ia64_psr(regs)->ed = 1;
- return;
- }
- if (user_mode(regs)) {
- si.si_signo = signal;
- si.si_errno = 0;
- si.si_code = code;
- si.si_addr = (void __user *) address;
- si.si_isr = isr;
- si.si_flags = __ISR_VALID;
- force_sig_info(signal, &si, current);
- return;
- }
- no_context:
- if ((isr & IA64_ISR_SP)
- || ((isr & IA64_ISR_NA) && (isr & IA64_ISR_CODE_MASK) == IA64_ISR_CODE_LFETCH))
- {
- /*
- * This fault was due to a speculative load or lfetch.fault, set the "ed"
- * bit in the psr to ensure forward progress. (Target register will get a
- * NaT for ld.s, lfetch will be canceled.)
- */
- ia64_psr(regs)->ed = 1;
- return;
- }
- /*
- * Since we have no vma's for region 5, we might get here even if the address is
- * valid, due to the VHPT walker inserting a non present translation that becomes
- * stale. If that happens, the non present fault handler already purged the stale
- * translation, which fixed the problem. So, we check to see if the translation is
- * valid, and return if it is.
- */
- if (REGION_NUMBER(address) == 5 && mapped_kernel_page_is_present(address))
- return;
- if (ia64_done_with_exception(regs))
- return;
- /*
- * Oops. The kernel tried to access some bad page. We'll have to terminate things
- * with extreme prejudice.
- */
- bust_spinlocks(1);
- if (address < PAGE_SIZE)
- printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference (address %016lx)\n", address);
- else
- printk(KERN_ALERT "Unable to handle kernel paging request at "
- "virtual address %016lx\n", address);
- if (die("Oops", regs, isr))
- regs = NULL;
- bust_spinlocks(0);
- if (regs)
- do_exit(SIGKILL);
- return;
- out_of_memory:
- up_read(&mm->mmap_sem);
- if (!user_mode(regs))
- goto no_context;
- pagefault_out_of_memory();
- }
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