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