Merge updates to algorithms from i386 switch code.
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matt
parent
7fa678813d
commit
38b7b2fcde
@ -1,4 +1,4 @@
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/* $NetBSD: pthread_switch.S,v 1.5 2003/09/07 14:47:56 cl Exp $ */
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/* $NetBSD: pthread_switch.S,v 1.6 2005/04/09 20:53:19 matt Exp $ */
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/*-
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* Copyright (c) 2001, 2003 The NetBSD Foundation, Inc.
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@ -62,13 +62,17 @@
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*/
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#define STACK_SWITCH(pt) \
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movl PT_TRAPUC(pt),%sp ; \
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movl PT_TRAPUC(pt),%sp; \
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bneq 1f; \
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movl PT_UC(pt),%sp; \
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1: clrl PT_TRAPUC(pt)
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1: subl2 $STACKSPACE,%sp; \
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clrl PT_TRAPUC(pt)
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/*
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* void pthread__switch(pthread_t self, pthread_t next);
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*/
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ENTRY(pthread__switch, 0)
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movab -(CONTEXTSIZE)(%sp), %sp
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subl2 $CONTEXTSIZE, %sp
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/* Get the current context */
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pushl %sp
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@ -92,9 +96,15 @@ switch_return_point:
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/*
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* Helper switch code used by pthread__locked_switch() and
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* pthread__upcall_switch() when they discover spinlock preemption.
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*
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* r3 = new pthread_t
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* r4 = lock flags
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* r5 = old pthread_t
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*/
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.globl pthread__switch_away
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pthread__switch_away:
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switch_away:
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STACK_SWITCH(%r3)
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/* If we're invoked from the switch-to-next provisions of
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@ -111,8 +121,8 @@ pthread__switch_away:
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* pt_spin_t *lock);
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*/
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ENTRY(pthread__locked_switch, 0)
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movab -(CONTEXTSIZE)(%sp),%sp
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movl 8(%ap),%r5
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subl2 $CONTEXTSIZE,%sp
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movl 8(%ap),%r5 /* r5 = next */
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/* Make sure we get continuted */
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incl PT_SPINLOCKS(%r5)
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@ -121,7 +131,7 @@ ENTRY(pthread__locked_switch, 0)
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pushl %sp
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calls $1, _getcontext_u
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movq 4(%ap),%r4
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movl 4(%ap),%r4 /* r4 = self */
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/* Edit the context to make it continue below, rather than here */
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movab locked_return_point, (UC_GREGS + _REG_PC)(%sp)
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@ -129,27 +139,31 @@ ENTRY(pthread__locked_switch, 0)
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STACK_SWITCH(%r5) /* sp = next->pt_uc */
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/* Check if the switcher was preempted and continued to here. */
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/*
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* Check if the original thread was preempted while holding
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* its queue lock.
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*/
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movl PT_NEXT(%r4),%r3
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beql 1f
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/* Yes, it was. Stash the thread we were going to switch to,
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* the lock the original thread was holding,
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* and switch to the next thread in the continuation chain.
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/*
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* Yes, it was. Stash the thread we were going to
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* switch to, the lock the original thread was holding,
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* and go to the next thread in the chain.
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* Mark the fact that this was a locked switch, and so the
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* thread does not need to be put on a run queue.
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* Don't release the lock. It's possible that if we do so,
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* PT_SWITCHTO will be stomped by another switch_lock and
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* preemption.
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*/
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movl 12(%ap), PT_HELDLOCK(%r4)
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movl %sp, PT_SWITCHTOUC(%r4)
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movl %r5, PT_SWITCHTO(%r4)
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incl PT_SPINLOCKS(%r4)
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movl 12(%ap), PT_HELDLOCK(%r4)
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decl PT_SPINLOCKS(%r4)
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/* %r3 = self->pt_next */
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movl %r3, %r5 /* r3 = self->pt_next */
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movl $1, %r4
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brw pthread__switch_away
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jbr switch_away /* r3 = next, r5 = next */
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/* No locked old-preemption */
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1: /* We've moved to the new stack, and the old context has been
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@ -162,17 +176,18 @@ ENTRY(pthread__locked_switch, 0)
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clrl *12(%ap)
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/* .. and remove the fake lock */
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incl PT_SPINLOCKS(%r5)
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decl PT_SPINLOCKS(%r5)
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/* Check if we were preempted while holding the fake lock. */
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movl PT_NEXT(%r5),%r3
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jeql setcontext
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/* Yes, we were. Go to the next element in the chain. */
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/* Yes, we were. Bummer. Go to the next element in the chain. */
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movl %sp, PT_SWITCHTOUC(%r5)
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movl %r5, PT_SWITCHTO(%r5)
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clrl %r4
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brw pthread__switch_away
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movl PT_NEXT(%r5), %r3
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movl $2, %r4
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jbr switch_away
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NOTREACHED
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locked_return_point:
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@ -185,16 +200,16 @@ locked_return_point:
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*/
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ENTRY(pthread__upcall_switch, 0)
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movq 4(%ap),%r4
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movq 4(%ap),%r4 /* r4 = self, r5 = next */
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/*
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* this code never returns, so we can treat s0-s6 as
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* this code never returns, so we can treat r0-r5 as
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* convenient registers that will be saved for us by callees,
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* but that we do not have to save.
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*/
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/* Create a "fake" lock count so that this code will be continued */
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incl PT_SPINLOCKS(%r4)
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incl PT_SPINLOCKS(%r5)
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STACK_SWITCH(%r5)
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@ -205,10 +220,12 @@ ENTRY(pthread__upcall_switch, 0)
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/* Yes, it was. Stash the thread we were going to switch to,
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* and switch to the next thread in the continuation chain.
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*/
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movl %sp, PT_SWITCHTOUC(%r4)
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movl %sp,PT_SWITCHTOUC(%r4)
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movq %r5,PT_SWITCHTO(%r4)
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movl $1,%r4
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brw pthread__switch_away
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movl PT_NEXT(%r4), %r3
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movl %r4, %r5
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movl $1, %r4
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jbr switch_away
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/* No old-upcall-preemption */
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1: movq %r4,-(%sp)
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@ -229,5 +246,6 @@ ENTRY(pthread__upcall_switch, 0)
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*/
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movl %sp, PT_SWITCHTOUC(%r5)
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movl %r5, PT_SWITCHTO(%r5)
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clrl %r4
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brw pthread__switch_away
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movl PT_NEXT(%r5), %r3
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movl $1, %r4
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jbr switch_away
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