106 lines
4.2 KiB
C
106 lines
4.2 KiB
C
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/*
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* Copyright (c) 2000-2006 Apple Computer, Inc. All rights reserved.
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*
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* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
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*
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* This file contains Original Code and/or Modifications of Original Code
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* as defined in and that are subject to the Apple Public Source License
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* Version 2.0 (the 'License'). You may not use this file except in
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* compliance with the License. The rights granted to you under the License
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* may not be used to create, or enable the creation or redistribution of,
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* unlawful or unlicensed copies of an Apple operating system, or to
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* circumvent, violate, or enable the circumvention or violation of, any
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* terms of an Apple operating system software license agreement.
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*
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* Please obtain a copy of the License at
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* http://www.opensource.apple.com/apsl/ and read it before using this file.
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*
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* The Original Code and all software distributed under the License are
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* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
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* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
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* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
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* Please see the License for the specific language governing rights and
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* limitations under the License.
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*
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* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
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*/
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#ifndef _DTRACE_PTSS_H_
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#define _DTRACE_PTSS_H_
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#ifdef __cplusplus
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extern "C" {
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#endif
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/*
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* The pid provider needs a small per thread scratch space,
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* in the address space of the user task. This code is used to
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* manage that space.
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*
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* High level design:
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*
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* To avoid serialization, this is a (mostly) lockless allocator. If
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* a new page has to be allocated, the process's sprlock will be acquired.
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*
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* NOTE: The dtrace copyin/copyout code is still the shared code that
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* can handle unmapped pages, so the scratch space isn't wired for now.
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* * Each page in user space is wired. It cannot be paged out, because
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* * dtrace's copyin/copyout is only guaranteed to handle pages already
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* * in memory.
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*
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* Each page in user space is represented by a dt_ptss_page. Page entries
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* are chained. Once allocated, a page is not freed until dtrace "cleans up"
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* that process.
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*
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* Clean up works like this:
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*
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* At process exit, free all kernel allocated memory, but ignore user pages.
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* At process exec, free all kernel allocated memory, but ignore user pages.
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* At process fork, free user pages copied from parent, and do not allocate kernel memory.
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*
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* This is making the assumption that it is faster to let the bulk vm_map
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* operations in exec/exit do their work, instead of explicit page free(s)
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* via mach_vm_deallocate.
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*
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* As each page is allocated, its entries are chained and added to the
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* free_list. To claim an entry, cas it off the list. When a thread exits,
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* cas its entry onto the list. We could potentially optimize this by
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* keeping a head/tail, and cas'ing the frees to the tail instead of the
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* head. Without evidence to support such a need, it seems better to keep
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* things simple for now.
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*/
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#define DTRACE_PTSS_SCRATCH_SPACE_PER_THREAD (64)
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#define DTRACE_PTSS_ENTRIES_PER_PAGE (PAGE_MAX_SIZE / DTRACE_PTSS_SCRATCH_SPACE_PER_THREAD)
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struct dtrace_ptss_page_entry {
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struct dtrace_ptss_page_entry* next;
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user_addr_t addr;
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user_addr_t write_addr;
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};
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struct dtrace_ptss_page {
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struct dtrace_ptss_page* next;
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struct dtrace_ptss_page_entry entries[DTRACE_PTSS_ENTRIES_PER_PAGE];
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};
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struct dtrace_ptss_page_entry* dtrace_ptss_claim_entry(struct proc* p); /* sprlock not held */
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struct dtrace_ptss_page_entry* dtrace_ptss_claim_entry_locked(struct proc* p); /* sprlock held */
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void dtrace_ptss_release_entry(struct proc* p, struct dtrace_ptss_page_entry* e);
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struct dtrace_ptss_page* dtrace_ptss_allocate_page(struct proc* p);
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void dtrace_ptss_free_page(struct proc* p, struct dtrace_ptss_page* ptss_page);
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void dtrace_ptss_enable(struct proc* p);
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void dtrace_ptss_exec_exit(struct proc* p);
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void dtrace_ptss_fork(struct proc* parent, struct proc* child);
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#ifdef __cplusplus
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}
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#endif
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#endif /* _DTRACE_PTSS_H_ */
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