x86: link vdso and boot with -z noexecstack --no-warn-rwx-segments
[muen/linux.git] / arch / x86 / events / 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 #include "probe.h"
6
7 static umode_t
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
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);