bsd/sys/ktrace.h

   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. */
  37 enum 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
  46 void ktrace_lock(void);
  47 void ktrace_unlock(void);
  48 void ktrace_assert_lock_held(void);
  49 void ktrace_start_single_threaded(void);
  50 void 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  */
  69 int 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  */
  77 void 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  */
  87 int 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  */
 100 void 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  */
 111 void 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  */
 119 int 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  */
 126 bool 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  */
 132 extern bool ktrace_keep_ownership_on_reset;
 133 extern int ktrace_root_set_owner_allowed;
 134 int ktrace_set_owning_pid(int pid);
 135
 136 /* Initialize ktrace.  Must only be called by the bootstrap thread. */
 137 void ktrace_init(void);
 138
 139 #endif /* SYS_KTRACE_H */