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);