![Peter Zijlstra](/assets/img/avatar_default.png)
In light of the recent pagefault and filemap_copy_from_user work I've gone through all the arch pagefault handlers to make sure the inc_preempt_count() 'feature' works as expected. Several sections of code (including the new filemap_copy_from_user) rely on the fact that faults do not take locks under increased preempt count. arch/x86_64 - good arch/powerpc - good arch/cris - fixed arch/i386 - good arch/parisc - fixed arch/sh - good arch/sparc - good arch/s390 - good arch/m68k - fixed arch/ppc - good arch/alpha - fixed arch/mips - good arch/sparc64 - good arch/ia64 - good arch/arm - fixed arch/um - good arch/avr32 - good arch/h8300 - NA arch/m32r - good arch/v850 - good arch/frv - fixed arch/m68knommu - NA arch/arm26 - fixed arch/sh64 - fixed arch/xtensa - good Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
220 lines
5.1 KiB
C
220 lines
5.1 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 <asm/setup.h>
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#include <asm/traps.h>
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#include <asm/system.h>
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#include <asm/uaccess.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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extern const int frame_extra_sizes[]; /* in m68k/kernel/signal.c */
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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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#ifdef DEBUG
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printk("send_fault_sig: %p,%d,%d\n", siginfo.si_addr, siginfo.si_signo, siginfo.si_code);
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#endif
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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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const struct exception_table_entry *fixup;
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/* Are we prepared to handle this kernel fault? */
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if ((fixup = search_exception_tables(regs->pc))) {
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struct pt_regs *tregs;
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/* Create a new four word stack frame, discarding the old
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one. */
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regs->stkadj = frame_extra_sizes[regs->format];
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tregs = (struct pt_regs *)((ulong)regs + regs->stkadj);
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tregs->vector = regs->vector;
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tregs->format = 0;
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tregs->pc = fixup->fixup;
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tregs->sr = regs->sr;
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return -1;
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}
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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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printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
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else
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printk(KERN_ALERT "Unable to handle kernel access");
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printk(" 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 write, fault;
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#ifdef DEBUG
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printk ("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,
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current->mm->pgd);
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#endif
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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 (in_atomic() || !mm)
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goto no_context;
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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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#ifdef DEBUG
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printk("do_page_fault: good_area\n");
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#endif
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write = 0;
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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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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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survive:
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fault = handle_mm_fault(mm, vma, address, write);
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#ifdef DEBUG
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printk("handle_mm_fault returns %d\n",fault);
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#endif
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switch (fault) {
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case VM_FAULT_MINOR:
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current->min_flt++;
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break;
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case VM_FAULT_MAJOR:
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current->maj_flt++;
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break;
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case VM_FAULT_SIGBUS:
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goto bus_err;
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default:
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goto out_of_memory;
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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 (is_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("VM: killing process %s\n", current->comm);
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if (user_mode(regs))
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do_exit(SIGKILL);
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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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