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/arch/ppc64/kernel/pmc.c

https://bitbucket.org/evzijst/gittest
C | 67 lines | 42 code | 14 blank | 11 comment | 1 complexity | cea869ae76e337e6bdc7925e48cbf071 MD5 | raw file
 1/*
 2 *  linux/arch/ppc64/kernel/pmc.c
 3 *
 4 *  Copyright (C) 2004 David Gibson, IBM Corporation.
 5 *
 6 *  This program is free software; you can redistribute it and/or
 7 *  modify it under the terms of the GNU General Public License
 8 *  as published by the Free Software Foundation; either version
 9 *  2 of the License, or (at your option) any later version.
10 */
11
12#include <linux/config.h>
13#include <linux/errno.h>
14#include <linux/spinlock.h>
15#include <linux/module.h>
16
17#include <asm/processor.h>
18#include <asm/pmc.h>
19
20/* Ensure exceptions are disabled */
21static void dummy_perf(struct pt_regs *regs)
22{
23	unsigned int mmcr0 = mfspr(SPRN_MMCR0);
24
25	mmcr0 &= ~(MMCR0_PMXE|MMCR0_PMAO);
26	mtspr(SPRN_MMCR0, mmcr0);
27}
28
29static spinlock_t pmc_owner_lock = SPIN_LOCK_UNLOCKED;
30static void *pmc_owner_caller; /* mostly for debugging */
31perf_irq_t perf_irq = dummy_perf;
32
33int reserve_pmc_hardware(perf_irq_t new_perf_irq)
34{
35	int err = 0;
36
37	spin_lock(&pmc_owner_lock);
38
39	if (pmc_owner_caller) {
40		printk(KERN_WARNING "reserve_pmc_hardware: "
41		       "PMC hardware busy (reserved by caller %p)\n",
42		       pmc_owner_caller);
43		err = -EBUSY;
44		goto out;
45	}
46
47	pmc_owner_caller = __builtin_return_address(0);
48	perf_irq = new_perf_irq ? : dummy_perf;
49
50 out:
51	spin_unlock(&pmc_owner_lock);
52	return err;
53}
54EXPORT_SYMBOL_GPL(reserve_pmc_hardware);
55
56void release_pmc_hardware(void)
57{
58	spin_lock(&pmc_owner_lock);
59
60	WARN_ON(! pmc_owner_caller);
61
62	pmc_owner_caller = NULL;
63	perf_irq = dummy_perf;
64
65	spin_unlock(&pmc_owner_lock);
66}
67EXPORT_SYMBOL_GPL(release_pmc_hardware);