mirror of https://github.com/dzavalishin/oskit/
124 lines
3.0 KiB
C
124 lines
3.0 KiB
C
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/*
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* Copyright (c) 1996, 1998, 1999, 2000 University of Utah and the Flux Group.
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* All rights reserved.
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*
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* This file is part of the Flux OSKit. The OSKit is free software, also known
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* as "open source;" you can redistribute it and/or modify it under the terms
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* of the GNU General Public License (GPL), version 2, as published by the Free
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* Software Foundation (FSF). To explore alternate licensing terms, contact
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* the University of Utah at csl-dist@cs.utah.edu or +1-801-585-3271.
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*
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* The OSKit is distributed in the hope that it will be useful, but WITHOUT ANY
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* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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* FOR A PARTICULAR PURPOSE. See the GPL for more details. You should have
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* received a copy of the GPL along with the OSKit; see the file COPYING. If
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* not, write to the FSF, 59 Temple Place #330, Boston, MA 02111-1307, USA.
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*/
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#include "svm_internal.h"
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#include <oskit/c/strings.h>
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#include <oskit/c/string.h>
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/*
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* Page fault handler. If the fault is for a mapped page that is paged
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* out or unallocated, take care of it.
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*
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* If its a protection or otherwise unallocated reference, pass to the
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* SEGV handler if it is defined. Otherwise panic.
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*/
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int
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svm_fault(oskit_addr_t vaddr, int eflags)
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{
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oskit_addr_t vpage;
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oskit_addr_t paddr;
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unsigned int mbits;
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int status = SVM_FAULT_OKAY;
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SVM_LOCK();
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#ifdef DEBUG_SVM
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printf("svm_fault: 0x%x 0x%x\n", vaddr, eflags);
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#endif
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vpage = trunc_page(vaddr);
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/*
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* If address not mapped, go right to SEGV handler.
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*/
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if (svm_mapped(vpage, PAGE_SIZE)) {
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status = SVM_FAULT_PAGEFLT;
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goto segv;
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}
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/*
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* Address is mapped. Is the page not even allocated (zero-fill)?
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* If so, find a page and map it. Just return.
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*/
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if (svm_find_mapping(vpage, &paddr, &mbits))
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panic("svm_fault: Invalid mapping for 0x%x!", vpage);
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if (mbits & PTE_MBITS_ZFILL) {
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/*
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* Zero fill. Allocate a page and map it.
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*/
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paddr = svm_alloc_physpage();
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#ifdef DEBUG_SVM
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printf("svm_fault: "
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"Mapping vaddr 0x%x to paddr 0x%x\n", vpage, paddr);
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#endif
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/*
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* Plug into ptov table if paging is enabled.
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*/
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if (svm_paging)
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SVM_PTOV(paddr) = vpage;
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/*
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* Change the mapping. Must be writable initially, since
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* it might be a read-only page.
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*/
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svm_change_mapping(vpage, paddr,
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PTE_MBITS_VALID|PTE_MBITS_RW);
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/*
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* Zero the page through the virtual address.
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*/
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memset((void *)vpage, 0, PAGE_SIZE);
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/*
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* Restore original mapping.
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*/
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mbits &= ~PTE_MBITS_ZFILL;
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mbits |= PTE_MBITS_VALID;
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svm_change_mapping(vpage, paddr, mbits);
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goto done;
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}
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/*
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* If there is a paddr, it might be a disk block number. Call the
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* pagein code to bring it in.
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*/
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if (mbits & PTE_MBITS_PAGED) {
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svm_pagein_page(vpage);
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goto done;
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}
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/*
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* Region is mapped and has a valid physical translation. Must
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* be a protection violation.
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*/
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status = SVM_FAULT_PROTFLT;
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segv:
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SVM_UNLOCK();
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if (svm_segv_handler)
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return (*svm_segv_handler)(vaddr, eflags);
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return status;
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done:
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SVM_UNLOCK();
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return SVM_FAULT_OKAY;
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}
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