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![Bojan Novković](/assets/img/avatar_default.png)
This commit replaces the linear transformation of kernel virtual addresses to kstack_object pindex values with a non-linear scheme that circumvents physical memory fragmentation caused by kernel stack guard pages. The new mapping scheme is used to effectively "skip" guard pages and assign pindices for non-guard pages in a contiguous fashion. The new allocation scheme requires that all default-sized kstack KVAs come from a separate, specially aligned region of the KVA space. For this to work, this commited introduces a dedicated per-domain kstack KVA arena used to allocate kernel stacks of default size. The behaviour on 32-bit platforms remains unchanged due to a significatly smaller KVA space. Aside from fullfilling the requirements imposed by the new scheme, a separate kstack KVA arena facilitates superpage promotion in the rest of kernel and causes most kstacks to have guard pages at both ends. Reviewed by: alc, kib, markj Tested by: markj Approved by: markj (mentor) Differential Revision: https://reviews.freebsd.org/D38852
80 lines
3.4 KiB
C
80 lines
3.4 KiB
C
/*-
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* SPDX-License-Identifier: (BSD-3-Clause AND MIT-CMU)
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*
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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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* This code is derived from software contributed to Berkeley by
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* The Mach Operating System project at Carnegie-Mellon University.
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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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* 3. 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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*
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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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#ifndef _VM_VM_KERN_H_
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#define _VM_VM_KERN_H_
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/* Kernel memory management definitions. */
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extern struct vm_map kernel_map_store;
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#define kernel_map (&kernel_map_store)
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extern struct vm_map exec_map_store;
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#define exec_map (&exec_map_store)
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extern struct vm_map pipe_map_store;
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#define pipe_map (&pipe_map_store)
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extern struct vmem *kernel_arena;
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extern struct vmem *kmem_arena;
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extern struct vmem *buffer_arena;
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extern struct vmem *transient_arena;
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extern struct vmem *memguard_arena;
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extern u_long vm_kmem_size;
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extern u_int exec_map_entries;
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extern u_int exec_map_entry_size;
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#endif /* _VM_VM_KERN_H_ */
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