807619d8ba
The reason for this is that the SPARC v9 architecture allows nested interrupts of higher priority/level than that of the current interrupt to occur (and we can't just entirely bypass this model, also, at least for tick interrupts, this also wouldn't be wise). However, when a preemption interrupt interrupts another interrupt of lower priority, f.e. PIL_ITHREAD, and that one in turn is nested by a third interrupt, f.e. PIL_TICK, with SCHED_ULE the execution of interrupts higher than PIL_PREEMPT may be migrated to another CPU. In particular, tl1_ret(), which is responsible for restoring the state of the CPU prior to entry to the interrupt based on the (also migrated) trap frame, then is run on a CPU which actually didn't receive the interrupt in question, causing an inappropriate processor interrupt level to be "restored". In turn, this causes interrupts of the first level, i.e. PIL_ITHREAD in the above scenario, to be blocked on the target of the migration until the correct PIL happens to be restored again on that CPU again. Making PIL_PREEMPT the lowest real priority, this effectively prevents this scenario from happening, as preemption interrupts no longer can interrupt any other interrupt besides stray ones (which is no issue). Thanks to attilio@ and especially mav@ for helping me to understand this problem at the 201208DevSummit. - Give PIL_STOP (which is also used for IPI_STOP_HARD, given that there's no real equivalent to NMIs on SPARC v9) the highest possible priority just below the hardwired PIL_TICK, so it has a chance to interrupt more things. MFC after: 1 week
114 lines
3.4 KiB
C
114 lines
3.4 KiB
C
/*-
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* Copyright (c) 2001 Jake Burkholder.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#ifndef _MACHINE_INTR_MACHDEP_H_
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#define _MACHINE_INTR_MACHDEP_H_
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#define IRSR_BUSY (1 << 5)
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#define PIL_MAX (1 << 4)
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#define IV_MAX (1 << 11)
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#define IR_FREE (PIL_MAX * 2)
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#define IH_SHIFT PTR_SHIFT
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#define IQE_SHIFT 5
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#define IV_SHIFT 6
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#define PIL_LOW 1 /* stray interrupts */
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#define PIL_PREEMPT 2 /* preempt idle thread CPU IPI */
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#define PIL_ITHREAD 3 /* interrupts that use ithreads */
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#define PIL_RENDEZVOUS 4 /* SMP rendezvous IPI */
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#define PIL_AST 5 /* asynchronous trap IPI */
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#define PIL_HARDCLOCK 6 /* hardclock broadcast */
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#define PIL_FILTER 11 /* filter interrupts */
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#define PIL_BRIDGE 12 /* bridge interrupts */
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#define PIL_STOP 13 /* stop CPU IPI */
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#define PIL_TICK 14 /* tick interrupts */
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#ifndef LOCORE
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#define INTR_BRIDGE INTR_MD1
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struct trapframe;
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typedef void ih_func_t(struct trapframe *);
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typedef void iv_func_t(void *);
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struct intr_request {
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struct intr_request *ir_next;
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iv_func_t *ir_func;
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void *ir_arg;
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u_int ir_vec;
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u_int ir_pri;
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};
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struct intr_controller {
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void (*ic_enable)(void *);
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void (*ic_disable)(void *);
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void (*ic_assign)(void *);
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void (*ic_clear)(void *);
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};
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struct intr_vector {
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iv_func_t *iv_func;
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void *iv_arg;
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const struct intr_controller *iv_ic;
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void *iv_icarg;
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struct intr_event *iv_event;
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u_int iv_pri;
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u_int iv_vec;
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u_int iv_mid;
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u_int iv_refcnt;
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u_int iv_pad[2];
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};
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extern ih_func_t *intr_handlers[];
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extern struct intr_vector intr_vectors[];
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#ifdef SMP
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void intr_add_cpu(u_int cpu);
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#endif
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int intr_bind(int vec, u_char cpu);
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int intr_describe(int vec, void *ih, const char *descr);
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void intr_setup(int level, ih_func_t *ihf, int pri, iv_func_t *ivf,
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void *iva);
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void intr_init1(void);
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void intr_init2(void);
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int intr_controller_register(int vec, const struct intr_controller *ic,
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void *icarg);
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int inthand_add(const char *name, int vec, int (*filt)(void *),
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void (*handler)(void *), void *arg, int flags, void **cookiep);
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int inthand_remove(int vec, void *cookie);
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ih_func_t intr_fast;
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#endif /* !LOCORE */
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#endif /* !_MACHINE_INTR_MACHDEP_H_ */
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