/* * This file is subject to the terms and conditions of the GNU General Public * License. See the file "COPYING" in the main directory of this archive * for more details. * * Copyright (C) 1995 - 2000 by Ralf Baechle */ #include <linux/signal.h> #include <linux/sched.h> #include <linux/interrupt.h> #include <linux/kernel.h> #include <linux/errno.h> #include <linux/string.h> #include <linux/types.h> #include <linux/ptrace.h> #include <linux/mman.h> #include <linux/mm.h> #include <linux/smp.h> #include <linux/vt_kern.h> /* For unblank_screen() */ #include <linux/module.h> #include <asm/branch.h> #include <asm/mmu_context.h> #include <asm/system.h> #include <asm/uaccess.h> #include <asm/ptrace.h> #include <asm/highmem.h> /* For VMALLOC_END */ /* * This routine handles page faults. It determines the address, * and the problem, and then passes it off to one of the appropriate * routines. */ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write, unsigned long address) { struct vm_area_struct * vma = NULL; struct task_struct *tsk = current; struct mm_struct *mm = tsk->mm; const int field = sizeof(unsigned long) * 2; siginfo_t info; int fault; #if 0 printk("Cpu%d[%s:%d:%0*lx:%ld:%0*lx]\n", raw_smp_processor_id(), current->comm, current->pid, field, address, write, field, regs->cp0_epc); #endif info.si_code = SEGV_MAPERR; /* * We fault-in kernel-space virtual memory on-demand. The * 'reference' page table is init_mm.pgd. * * NOTE! We MUST NOT take any locks for this case. We may * be in an interrupt or a critical region, and should * only copy the information from the master page table, * nothing more. */ if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END)) goto vmalloc_fault; #ifdef MODULE_START if (unlikely(address >= MODULE_START && address < MODULE_END)) goto vmalloc_fault; #endif /* * If we're in an interrupt or have no user * context, we must not take the fault.. */ if (in_atomic() || !mm) goto bad_area_nosemaphore; down_read(&mm->mmap_sem); vma = find_vma(mm, address); if (!vma) goto bad_area; if (vma->vm_start <= address) goto good_area; if (!(vma->vm_flags & VM_GROWSDOWN)) goto bad_area; if (expand_stack(vma, address)) goto bad_area; /* * Ok, we have a good vm_area for this memory access, so * we can handle it.. */ good_area: info.si_code = SEGV_ACCERR; if (write) { if (!(vma->vm_flags & VM_WRITE)) goto bad_area; } else { if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))) goto bad_area; } survive: /* * 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, write); if (unlikely(fault & VM_FAULT_ERROR)) { if (fault & VM_FAULT_OOM) goto out_of_memory; else if (fault & VM_FAULT_SIGBUS) goto do_sigbus; BUG(); } if (fault & VM_FAULT_MAJOR) tsk->maj_flt++; else tsk->min_flt++; up_read(&mm->mmap_sem); return; /* * Something tried to access memory that isn't in our memory map.. * Fix it, but check if it's kernel or user first.. */ bad_area: up_read(&mm->mmap_sem); bad_area_nosemaphore: /* User mode accesses just cause a SIGSEGV */ if (user_mode(regs)) { tsk->thread.cp0_badvaddr = address; tsk->thread.error_code = write; #if 0 printk("do_page_fault() #2: sending SIGSEGV to %s for " "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n", tsk->comm, write ? "write access to" : "read access from", field, address, field, (unsigned long) regs->cp0_epc, field, (unsigned long) regs->regs[31]); #endif info.si_signo = SIGSEGV; info.si_errno = 0; /* info.si_code has been set above */ info.si_addr = (void __user *) address; force_sig_info(SIGSEGV, &info, tsk); return; } no_context: /* Are we prepared to handle this kernel fault? */ if (fixup_exception(regs)) { current->thread.cp0_baduaddr = address; return; } /* * Oops. The kernel tried to access some bad page. We'll have to * terminate things with extreme prejudice. */ bust_spinlocks(1); printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at " "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n", raw_smp_processor_id(), field, address, field, regs->cp0_epc, field, regs->regs[31]); die("Oops", regs); /* * We ran out of memory, or some other thing happened to us that made * us unable to handle the page fault gracefully. */ out_of_memory: up_read(&mm->mmap_sem); if (is_init(tsk)) { yield(); down_read(&mm->mmap_sem); goto survive; } printk("VM: killing process %s\n", tsk->comm); if (user_mode(regs)) do_exit(SIGKILL); goto no_context; do_sigbus: up_read(&mm->mmap_sem); /* Kernel mode? Handle exceptions or die */ if (!user_mode(regs)) goto no_context; else /* * Send a sigbus, regardless of whether we were in kernel * or user mode. */ #if 0 printk("do_page_fault() #3: sending SIGBUS to %s for " "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n", tsk->comm, write ? "write access to" : "read access from", field, address, field, (unsigned long) regs->cp0_epc, field, (unsigned long) regs->regs[31]); #endif tsk->thread.cp0_badvaddr = address; info.si_signo = SIGBUS; info.si_errno = 0; info.si_code = BUS_ADRERR; info.si_addr = (void __user *) address; force_sig_info(SIGBUS, &info, tsk); return; vmalloc_fault: { /* * Synchronize this task's top level page-table * with the 'reference' page table. * * Do _not_ use "tsk" here. We might be inside * an interrupt in the middle of a task switch.. */ int offset = __pgd_offset(address); pgd_t *pgd, *pgd_k; pud_t *pud, *pud_k; pmd_t *pmd, *pmd_k; pte_t *pte_k; pgd = (pgd_t *) pgd_current[raw_smp_processor_id()] + offset; pgd_k = init_mm.pgd + offset; if (!pgd_present(*pgd_k)) goto no_context; set_pgd(pgd, *pgd_k); pud = pud_offset(pgd, address); pud_k = pud_offset(pgd_k, address); if (!pud_present(*pud_k)) goto no_context; pmd = pmd_offset(pud, address); pmd_k = pmd_offset(pud_k, address); if (!pmd_present(*pmd_k)) goto no_context; set_pmd(pmd, *pmd_k); pte_k = pte_offset_kernel(pmd_k, address); if (!pte_present(*pte_k)) goto no_context; return; } }