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represented a write access that is allowed to override write protection. Until now, VM_PROT_OVERRIDE_WRITE has been used to write breakpoints into text pages. Text pages are not just write protected but they are also copy-on-write. VM_PROT_OVERRIDE_WRITE overrides the write protection on the text page and triggers the replication of the page so that the breakpoint will be written to a private copy. However, here is where things become confused. It is the debugger, not the process being debugged that requires write access to the copied page. Nonetheless, the copied page is being mapped into the process with write access enabled. In other words, once the debugger sets a breakpoint within a text page, the program can write to its private copy of that text page. Whereas prior to setting the breakpoint, a SIGSEGV would have occurred upon a write access. VM_PROT_COPY addresses this problem. The combination of VM_PROT_READ and VM_PROT_COPY forces the replication of a copy-on-write page even though the access is only for read. Moreover, the replicated page is only mapped into the process with read access, and not write access. Reviewed by: kib MFC after: 4 weeks
153 lines
5.2 KiB
C
153 lines
5.2 KiB
C
/*-
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)vm.h 8.2 (Berkeley) 12/13/93
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* @(#)vm_prot.h 8.1 (Berkeley) 6/11/93
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* @(#)vm_inherit.h 8.1 (Berkeley) 6/11/93
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*
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* Copyright (c) 1987, 1990 Carnegie-Mellon University.
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* All rights reserved.
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*
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* Authors: Avadis Tevanian, Jr., Michael Wayne Young
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*
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* Permission to use, copy, modify and distribute this software and
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* its documentation is hereby granted, provided that both the copyright
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* notice and this permission notice appear in all copies of the
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* software, derivative works or modified versions, and any portions
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* thereof, and that both notices appear in supporting documentation.
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*
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* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
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* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
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* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
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*
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* Carnegie Mellon requests users of this software to return to
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*
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* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
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* School of Computer Science
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* Carnegie Mellon University
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* Pittsburgh PA 15213-3890
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*
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* any improvements or extensions that they make and grant Carnegie the
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* rights to redistribute these changes.
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*
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* $FreeBSD$
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*/
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#ifndef VM_H
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#define VM_H
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#include <machine/vm.h>
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typedef char vm_inherit_t; /* inheritance codes */
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#define VM_INHERIT_SHARE ((vm_inherit_t) 0)
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#define VM_INHERIT_COPY ((vm_inherit_t) 1)
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#define VM_INHERIT_NONE ((vm_inherit_t) 2)
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#define VM_INHERIT_DEFAULT VM_INHERIT_COPY
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typedef u_char vm_prot_t; /* protection codes */
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#define VM_PROT_NONE ((vm_prot_t) 0x00)
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#define VM_PROT_READ ((vm_prot_t) 0x01)
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#define VM_PROT_WRITE ((vm_prot_t) 0x02)
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#define VM_PROT_EXECUTE ((vm_prot_t) 0x04)
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#define VM_PROT_COPY ((vm_prot_t) 0x08) /* copy-on-read */
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#define VM_PROT_ALL (VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE)
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#define VM_PROT_RW (VM_PROT_READ|VM_PROT_WRITE)
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#define VM_PROT_DEFAULT VM_PROT_ALL
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enum obj_type { OBJT_DEFAULT, OBJT_SWAP, OBJT_VNODE, OBJT_DEVICE, OBJT_PHYS,
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OBJT_DEAD, OBJT_SG };
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typedef u_char objtype_t;
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union vm_map_object;
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typedef union vm_map_object vm_map_object_t;
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struct vm_map_entry;
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typedef struct vm_map_entry *vm_map_entry_t;
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struct vm_map;
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typedef struct vm_map *vm_map_t;
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struct vm_object;
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typedef struct vm_object *vm_object_t;
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#ifndef _KERNEL
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/*
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* This is defined in <sys/types.h> for the kernel so that non-vm kernel
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* sources (mainly Mach-derived ones such as ddb) don't have to include
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* vm stuff. Defining it there for applications might break things.
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* Define it here for "applications" that include vm headers (e.g.,
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* genassym).
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*/
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typedef int boolean_t;
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/*
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* The exact set of memory attributes is machine dependent. However, every
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* machine is required to define VM_MEMATTR_DEFAULT.
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*/
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typedef char vm_memattr_t; /* memory attribute codes */
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/*
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* This is defined in <sys/types.h> for the kernel so that vnode_if.h
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* doesn't have to include <vm/vm.h>.
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*/
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struct vm_page;
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typedef struct vm_page *vm_page_t;
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#endif /* _KERNEL */
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struct vm_reserv;
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typedef struct vm_reserv *vm_reserv_t;
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/*
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* Information passed from the machine-independant VM initialization code
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* for use by machine-dependant code (mainly for MMU support)
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*/
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struct kva_md_info {
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vm_offset_t buffer_sva;
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vm_offset_t buffer_eva;
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vm_offset_t clean_sva;
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vm_offset_t clean_eva;
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vm_offset_t pager_sva;
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vm_offset_t pager_eva;
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};
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extern struct kva_md_info kmi;
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extern void vm_ksubmap_init(struct kva_md_info *);
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struct uidinfo;
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int swap_reserve(vm_ooffset_t incr);
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int swap_reserve_by_uid(vm_ooffset_t incr, struct uidinfo *uip);
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void swap_reserve_force(vm_ooffset_t incr);
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void swap_release(vm_ooffset_t decr);
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void swap_release_by_uid(vm_ooffset_t decr, struct uidinfo *uip);
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#endif /* VM_H */
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