c6a37e8413
critical_enter() and critical_exit() are now solely a mechanism for deferring kernel preemptions. They no longer have any affect on interrupts. This means that standalone critical sections are now very cheap as they are simply unlocked integer increments and decrements for the common case. Spin mutexes now use a separate KPI implemented in MD code: spinlock_enter() and spinlock_exit(). This KPI is responsible for providing whatever MD guarantees are needed to ensure that a thread holding a spin lock won't be preempted by any other code that will try to lock the same lock. For now all archs continue to block interrupts in a "spinlock section" as they did formerly in all critical sections. Note that I've also taken this opportunity to push a few things into MD code rather than MI. For example, critical_fork_exit() no longer exists. Instead, MD code ensures that new threads have the correct state when they are created. Also, we no longer try to fixup the idlethreads for APs in MI code. Instead, each arch sets the initial curthread and adjusts the state of the idle thread it borrows in order to perform the initial context switch. This change is largely a big NOP, but the cleaner separation it provides will allow for more efficient alternative locking schemes in other parts of the kernel (bare critical sections rather than per-CPU spin mutexes for per-CPU data for example). Reviewed by: grehan, cognet, arch@, others Tested on: i386, alpha, sparc64, powerpc, arm, possibly more
70 lines
2.3 KiB
C
70 lines
2.3 KiB
C
/* $FreeBSD$ */
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/* From: NetBSD: proc.h,v 1.3 1997/04/06 08:47:36 cgd Exp */
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/*-
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* Copyright (c) 1994, 1995 Carnegie-Mellon University.
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* All rights reserved.
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*
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* Author: Chris G. Demetriou
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*
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* Permission to use, copy, modify and distribute this software and
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* its documentation is hereby granted, provided that both the copyright
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* notice and this permission notice appear in all copies of the
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* software, derivative works or modified versions, and any portions
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* thereof, and that both notices appear in supporting documentation.
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*
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* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
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* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
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* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
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*
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* Carnegie Mellon requests users of this software to return to
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*
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* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
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* School of Computer Science
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* Carnegie Mellon University
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* Pittsburgh PA 15213-3890
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*
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* any improvements or extensions that they make and grant Carnegie the
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* rights to redistribute these changes.
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*/
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#ifndef _MACHINE_PROC_H_
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#define _MACHINE_PROC_H_
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/*
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* Machine-dependent part of the proc struct for the Alpha.
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*/
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struct mdbpt {
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vm_offset_t addr;
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u_int32_t contents;
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};
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#define MDTD_FPUSED 0x0001 /* Process used the FPU */
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#define MDTD_STEP1 0x0002 /* Single step normal instruction */
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#define MDTD_STEP2 0x0004 /* Single step branch instruction */
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#define MDTD_HAEUSED 0x0008 /* Process used the HAE */
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struct mdthread {
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u_long md_flags;
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struct pcb *md_pcbpaddr; /* phys addr of the pcb */
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struct mdbpt md_sstep[2]; /* two single step breakpoints */
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u_int64_t md_hae; /* user HAE register value */
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void *osf_sigtramp; /* user-level signal trampoline */
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u_int md_kernnest; /* nesting level in the kernel */
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register_t md_saved_ipl; /* save IPL for critical section */
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u_int md_spinlock_count;
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};
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#define MDP_UAC_NOPRINT 0x0010 /* Don't print unaligned traps */
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#define MDP_UAC_NOFIX 0x0020 /* Don't fixup unaligned traps */
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#define MDP_UAC_SIGBUS 0x0040 /* Deliver SIGBUS upon
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unaligned access */
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#define MDP_UAC_MASK (MDP_UAC_NOPRINT | MDP_UAC_NOFIX | MDP_UAC_SIGBUS)
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struct mdproc {
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u_int md_uac; /* (c) Unaligned Access Check flags. */
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};
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#endif /* !_MACHINE_PROC_H_ */
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