8154c5d22d
Currently we have the lppaca structs as a simple array of NR_CPUS entries, taking up space in the data section of the kernel image. In future we would like to allocate them dynamically, so this abstracts out the accesses to the array, making it easier to change how we locate the lppaca for a given cpu in future. Specifically, lppaca[cpu] changes to lppaca_of(cpu). Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
96 lines
2.6 KiB
C
96 lines
2.6 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/module.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) || defined(CONFIG_PPC_ISERIES)
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#include <asm/hvcall.h>
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#include <asm/iseries/hv_call.h>
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#include <asm/smp.h>
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#include <asm/firmware.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 = 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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if (firmware_has_feature(FW_FEATURE_ISERIES))
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HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc,
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((u64)holder_cpu << 32) | yield_count);
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#ifdef CONFIG_PPC_SPLPAR
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else
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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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#endif
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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 = 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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if (firmware_has_feature(FW_FEATURE_ISERIES))
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HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc,
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((u64)holder_cpu << 32) | yield_count);
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#ifdef CONFIG_PPC_SPLPAR
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else
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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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#endif
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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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