probe.c

 1// SPDX-License-Identifier: GPL-2.0
 2#include <linux/export.h>
 3#include <linux/types.h>
 4#include <linux/bits.h>
 5
 6#include <asm/msr.h>
 7#include "probe.h"
 8
 9static umode_t
10not_visible(struct kobject *kobj, struct attribute *attr, int i)
11{
12	return 0;
13}
14
15/*
16 * Accepts msr[] array with non populated entries as long as either
17 * msr[i].msr is 0 or msr[i].grp is NULL. Note that the default sysfs
18 * visibility is visible when group->is_visible callback is set.
19 */
20unsigned long
21perf_msr_probe(struct perf_msr *msr, int cnt, bool zero, void *data)
22{
23	unsigned long avail = 0;
24	unsigned int bit;
25	u64 val;
26
27	if (cnt >= BITS_PER_LONG)
28		return 0;
29
30	for (bit = 0; bit < cnt; bit++) {
31		if (!msr[bit].no_check) {
32			struct attribute_group *grp = msr[bit].grp;
33			u64 mask;
34
35			/* skip entry with no group */
36			if (!grp)
37				continue;
38
39			grp->is_visible = not_visible;
40
41			/* skip unpopulated entry */
42			if (!msr[bit].msr)
43				continue;
44
45			if (msr[bit].test && !msr[bit].test(bit, data))
46				continue;
47			/* Virt sucks; you cannot tell if a R/O MSR is present :/ */
48			if (rdmsrq_safe(msr[bit].msr, &val))
49				continue;
50
51			mask = msr[bit].mask;
52			if (!mask)
53				mask = ~0ULL;
54			/* Disable zero counters if requested. */
55			if (!zero && !(val & mask))
56				continue;
57
58			grp->is_visible = NULL;
59		}
60		avail |= BIT(bit);
61	}
62
63	return avail;
64}
65EXPORT_SYMBOL_GPL(perf_msr_probe);