1/*
2 * Copyright (c) 2015 Apple 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 SYS_KTRACE_H
30#define SYS_KTRACE_H
31
32#include <stdint.h>
33
34#include <kern/locks.h>
35
36/* The states that ktrace can be in. */
37enum ktrace_state {
38 /* No tool has configured ktrace. */
39 KTRACE_STATE_OFF = 0,
40 /* A foreground tool has configured ktrace. */
41 KTRACE_STATE_FG,
42 /* A background tool has configured ktrace. */
43 KTRACE_STATE_BG
44};
45
46void ktrace_lock(void);
47void ktrace_unlock(void);
48void ktrace_assert_lock_held(void);
49void ktrace_start_single_threaded(void);
50void ktrace_end_single_threaded(void);
51
52/*
53 * Subsystems that use ktrace to manage ownership. These values are passed as
54 * part of the `*_mask` arguments in `ktrace_configure` and `ktrace_reset`.
55 */
56#define KTRACE_KDEBUG (1 << 0)
57#define KTRACE_KPERF (1 << 1)
58
59/*
60 * Used by subsystems to inform ktrace that a configuration is occurring.
61 * Validates whether the current process has privileges to configure
62 * ktrace. Pass the subsystem(s) being configured in config_mask.
63 *
64 * `ktrace_lock` must be held.
65 *
66 * Returns 0 if configuration is allowed, EPERM if process is not privileged,
67 * and EBUSY if ktrace is owned by another process.
68 */
69int ktrace_configure(uint32_t config_mask);
70
71/*
72 * Tell ktrace to reset a configuration. Pass the susbsystem(s) that are to
73 * be reset in the reset_mask.
74 *
75 * `ktrace_lock` must be held.
76 */
77void ktrace_reset(uint32_t reset_mask);
78
79/*
80 * Determine if the current process can read the configuration of ktrace.
81 * Only the owning process or a root privileged process is allowed.
82 *
83 * `ktrace_lock` must be held.
84 *
85 * Returns 0 if allowed, EPERM otherwise.
86 */
87int ktrace_read_check(void);
88
89/*
90 * With certain boot-args, the kernel can start tracing without user space
91 * intervention. With `trace=<n_events>`, the kernel will start tracing at
92 * boot. With `trace_wake=<n_events>`, the kernel will start tracing on the
93 * wake path out of hibernation (on Intel only).
94 *
95 * In these cases, ktrace must be aware of the state changes. This function
96 * should be called whenever the kernel initiates configuring ktrace.
97 *
98 * `ktrace_lock` must be held.
99 */
100void ktrace_kernel_configure(uint32_t config_mask);
101
102/*
103 * This KPI allows kernel systems to disable ktrace. ktrace will only be
104 * disabled if the state matches the provided state_to_match.
105 *
106 * This does not reset the configuration of any subsystems -- it just makes
107 * them stop logging events or sampling data.
108 *
109 * `ktrace_lock` must be held.
110 */
111void ktrace_disable(enum ktrace_state state_to_match);
112
113/*
114 * Returns the pid of the process that owns ktrace. If ktrace is unowned,
115 * returns 0.
116 *
117 * `ktrace_lock` must be held.
118 */
119int ktrace_get_owning_pid(void);
120
121/*
122 * Returns true if background tracing is active, false otherwise.
123 *
124 * `ktrace_lock` must be held.
125 */
126bool ktrace_background_active(void);
127
128/*
129 * These functions exist for the transition for kperf to allow blessing other
130 * processes. They should not be used by other clients.
131 */
132extern bool ktrace_keep_ownership_on_reset;
133extern int ktrace_root_set_owner_allowed;
134int ktrace_set_owning_pid(int pid);
135
136/* Initialize ktrace. Must only be called by the bootstrap thread. */
137void ktrace_init(void);
138
139#endif /* SYS_KTRACE_H */
140