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