LXR linux/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
   7static umode_t
   8not_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 */
  18unsigned long
  19perf_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}
  63EXPORT_SYMBOL_GPL(perf_msr_probe);
  64