86 lines
3.6 KiB
C
86 lines
3.6 KiB
C
/*
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* Copyright (c) 2013 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 _SYS_KERN_OVERRIDES_H
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#define _SYS_KERN_OVERRIDES_H
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#include <sys/cdefs.h>
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#include <sys/param.h>
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#include <sys/types.h>
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#include <stdint.h>
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__BEGIN_DECLS
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/*
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* system_override() system call
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*
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* The system_override() syscall is used to modify some kernel performance mechanisms.
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* The system call needs a special entitlement and should be used with extreme caution.
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* A misuse of this syscall could lead to severe performance and battery life issues.
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*
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* The caller needs to specify the mask for the specific mechanisms to modify and a
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* timeout. The implementation of this system call blocks the thread in the syscall
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* for the duration specified in the call. Blocking a thread in the system call allows
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* the kernel to revert the modification in case the calling process dies. It also
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* makes the change of behavior extremely obvious due to the backtrace of the calling
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* thread.
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*
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* Multiple agents are allowed to call this interface at the same time. The behavior
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* change is effective from the time the first call is made (for a specific mechanism)
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* until the longest timeout specified by any agent. If the caller wishes to disable
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* the behavior change caused by itself, it can call the same interface with the
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* SYS_OVERRIDE_DISABLE flag and the mechanism mask from another thread in the same
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* process. Note that this does not break out the original thread from the block
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* immediately. It simply undoes the mechanism change underneath.
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*
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* The currently supported overrides are:
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* - SYS_OVERRIDE_IO_THROTTLE: Modifies I/O throttling behavior
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* - SYS_OVERRIDE_CPU_THROTTLE: Modifies background stepper throttling mechanism
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* - SYS_OVERRIDE_FAST_JETSAM: Modifies jetsam behavior to use aggressive parallel jetsam
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*
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*/
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/* System Overrides Flags */
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#define SYS_OVERRIDE_DISABLE (~(~0ull >> 1))
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#define SYS_OVERRIDE_IO_THROTTLE 0x1
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#define SYS_OVERRIDE_CPU_THROTTLE 0x2
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#define SYS_OVERRIDE_FAST_JETSAM 0x4
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#define SYS_OVERRIDE_FLAGS_MASK (SYS_OVERRIDE_DISABLE | SYS_OVERRIDE_IO_THROTTLE | SYS_OVERRIDE_CPU_THROTTLE | SYS_OVERRIDE_FAST_JETSAM)
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#ifdef BSD_KERNEL_PRIVATE
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void init_system_override(void);
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#endif
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#ifndef KERNEL
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int system_override(uint64_t timeout, uint64_t flags);
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#endif
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__END_DECLS
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#endif /*_SYS_KERN_OVERRIDES_H */
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