1 | /* |
2 | * Copyright (c) 2000-2006 Apple Computer, Inc. All rights reserved. |
3 | * |
4 | * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ |
5 | * |
6 | * This file contains Original Code and/or Modifications of Original Code |
7 | * as defined in and that are subject to the Apple Public Source License |
8 | * Version 2.0 (the 'License'). You may not use this file except in |
9 | * compliance with the License. The rights granted to you under the License |
10 | * may not be used to create, or enable the creation or redistribution of, |
11 | * unlawful or unlicensed copies of an Apple operating system, or to |
12 | * circumvent, violate, or enable the circumvention or violation of, any |
13 | * terms of an Apple operating system software license agreement. |
14 | * |
15 | * Please obtain a copy of the License at |
16 | * http://www.opensource.apple.com/apsl/ and read it before using this file. |
17 | * |
18 | * The Original Code and all software distributed under the License are |
19 | * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER |
20 | * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, |
21 | * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, |
22 | * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. |
23 | * Please see the License for the specific language governing rights and |
24 | * limitations under the License. |
25 | * |
26 | * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ |
27 | */ |
28 | |
29 | #ifndef _DTRACE_PTSS_H_ |
30 | #define _DTRACE_PTSS_H_ |
31 | |
32 | #ifdef __cplusplus |
33 | extern "C" { |
34 | #endif |
35 | |
36 | /* |
37 | * The pid provider needs a small per thread scratch space, |
38 | * in the address space of the user task. This code is used to |
39 | * manage that space. |
40 | * |
41 | * High level design: |
42 | * |
43 | * To avoid serialization, this is a (mostly) lockless allocator. If |
44 | * a new page has to be allocated, the process's sprlock will be acquired. |
45 | * |
46 | * NOTE: The dtrace copyin/copyout code is still the shared code that |
47 | * can handle unmapped pages, so the scratch space isn't wired for now. |
48 | * * Each page in user space is wired. It cannot be paged out, because |
49 | * * dtrace's copyin/copyout is only guaranteed to handle pages already |
50 | * * in memory. |
51 | * |
52 | * Each page in user space is represented by a dt_ptss_page. Page entries |
53 | * are chained. Once allocated, a page is not freed until dtrace "cleans up" |
54 | * that process. |
55 | * |
56 | * Clean up works like this: |
57 | * |
58 | * At process exit, free all kernel allocated memory, but ignore user pages. |
59 | * At process exec, free all kernel allocated memory, but ignore user pages. |
60 | * At process fork, free user pages copied from parent, and do not allocate kernel memory. |
61 | * |
62 | * This is making the assumption that it is faster to let the bulk vm_map |
63 | * operations in exec/exit do their work, instead of explicit page free(s) |
64 | * via mach_vm_deallocate. |
65 | * |
66 | * As each page is allocated, its entries are chained and added to the |
67 | * free_list. To claim an entry, cas it off the list. When a thread exits, |
68 | * cas its entry onto the list. We could potentially optimize this by |
69 | * keeping a head/tail, and cas'ing the frees to the tail instead of the |
70 | * head. Without evidence to support such a need, it seems better to keep |
71 | * things simple for now. |
72 | */ |
73 | |
74 | |
75 | #define DTRACE_PTSS_SCRATCH_SPACE_PER_THREAD (64) |
76 | |
77 | #define DTRACE_PTSS_ENTRIES_PER_PAGE (PAGE_MAX_SIZE / DTRACE_PTSS_SCRATCH_SPACE_PER_THREAD) |
78 | |
79 | struct dtrace_ptss_page_entry { |
80 | struct dtrace_ptss_page_entry* next; |
81 | user_addr_t addr; |
82 | user_addr_t write_addr; |
83 | }; |
84 | |
85 | struct dtrace_ptss_page { |
86 | struct dtrace_ptss_page* next; |
87 | struct dtrace_ptss_page_entry entries[DTRACE_PTSS_ENTRIES_PER_PAGE]; |
88 | }; |
89 | |
90 | struct dtrace_ptss_page_entry* dtrace_ptss_claim_entry(struct proc* p); /* sprlock not held */ |
91 | struct dtrace_ptss_page_entry* dtrace_ptss_claim_entry_locked(struct proc* p); /* sprlock held */ |
92 | void dtrace_ptss_release_entry(struct proc* p, struct dtrace_ptss_page_entry* e); |
93 | |
94 | struct dtrace_ptss_page* dtrace_ptss_allocate_page(struct proc* p); |
95 | void dtrace_ptss_free_page(struct proc* p, struct dtrace_ptss_page* ptss_page); |
96 | |
97 | void dtrace_ptss_enable(struct proc* p); |
98 | void dtrace_ptss_exec_exit(struct proc* p); |
99 | void dtrace_ptss_fork(struct proc* parent, struct proc* child); |
100 | |
101 | #ifdef __cplusplus |
102 | } |
103 | #endif |
104 | |
105 | #endif /* _DTRACE_PTSS_H_ */ |
106 | |