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7ffcf8ec26
The lppaca, slb_shadow and dtl_entry hypervisor structures are big endian, so we have to byte swap them in little endian builds. LE KVM hosts will also need to be fixed but for now add an #error to remind us. Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
82 lines
2.2 KiB
C
82 lines
2.2 KiB
C
/*
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* Spin and read/write lock operations.
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*
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* Copyright (C) 2001-2004 Paul Mackerras <paulus@au.ibm.com>, IBM
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* Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
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* Copyright (C) 2002 Dave Engebretsen <engebret@us.ibm.com>, IBM
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* Rework to support virtual processors
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/kernel.h>
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#include <linux/spinlock.h>
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#include <linux/export.h>
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#include <linux/stringify.h>
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#include <linux/smp.h>
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/* waiting for a spinlock... */
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#if defined(CONFIG_PPC_SPLPAR)
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#include <asm/hvcall.h>
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#include <asm/smp.h>
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void __spin_yield(arch_spinlock_t *lock)
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{
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unsigned int lock_value, holder_cpu, yield_count;
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lock_value = lock->slock;
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if (lock_value == 0)
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return;
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holder_cpu = lock_value & 0xffff;
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BUG_ON(holder_cpu >= NR_CPUS);
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yield_count = be32_to_cpu(lppaca_of(holder_cpu).yield_count);
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if ((yield_count & 1) == 0)
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return; /* virtual cpu is currently running */
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rmb();
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if (lock->slock != lock_value)
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return; /* something has changed */
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plpar_hcall_norets(H_CONFER,
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get_hard_smp_processor_id(holder_cpu), yield_count);
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}
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/*
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* Waiting for a read lock or a write lock on a rwlock...
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* This turns out to be the same for read and write locks, since
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* we only know the holder if it is write-locked.
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*/
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void __rw_yield(arch_rwlock_t *rw)
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{
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int lock_value;
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unsigned int holder_cpu, yield_count;
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lock_value = rw->lock;
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if (lock_value >= 0)
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return; /* no write lock at present */
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holder_cpu = lock_value & 0xffff;
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BUG_ON(holder_cpu >= NR_CPUS);
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yield_count = be32_to_cpu(lppaca_of(holder_cpu).yield_count);
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if ((yield_count & 1) == 0)
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return; /* virtual cpu is currently running */
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rmb();
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if (rw->lock != lock_value)
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return; /* something has changed */
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plpar_hcall_norets(H_CONFER,
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get_hard_smp_processor_id(holder_cpu), yield_count);
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}
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#endif
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void arch_spin_unlock_wait(arch_spinlock_t *lock)
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{
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while (lock->slock) {
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HMT_low();
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if (SHARED_PROCESSOR)
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__spin_yield(lock);
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}
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HMT_medium();
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}
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EXPORT_SYMBOL(arch_spin_unlock_wait);
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