// SPDX-License-Identifier: GPL-2.0
#include <linux/export.h>
#include <linux/types.h>
#include <linux/bits.h>

#include <asm/msr.h>
#include "probe.h"

static umode_t
not_visible(struct kobject *kobj, struct attribute *attr, int i)
{
        return 0;
}

/*
 * Accepts msr[] array with non populated entries as long as either
 * msr[i].msr is 0 or msr[i].grp is NULL. Note that the default sysfs
 * visibility is visible when group->is_visible callback is set.
 */
unsigned long
perf_msr_probe(struct perf_msr *msr, int cnt, bool zero, void *data)
{
        unsigned long avail = 0;
        unsigned int bit;
        u64 val;

        if (cnt >= BITS_PER_LONG)
                return 0;

        for (bit = 0; bit < cnt; bit++) {
                if (!msr[bit].no_check) {
                        struct attribute_group *grp = msr[bit].grp;
                        u64 mask;

                        /* skip entry with no group */
                        if (!grp)
                                continue;

                        grp->is_visible = not_visible;

                        /* skip unpopulated entry */
                        if (!msr[bit].msr)
                                continue;

                        if (msr[bit].test && !msr[bit].test(bit, data))
                                continue;
                        /* Virt sucks; you cannot tell if a R/O MSR is present :/ */
                        if (rdmsrq_safe(msr[bit].msr, &val))
                                continue;

                        mask = msr[bit].mask;
                        if (!mask)
                                mask = ~0ULL;
                        /* Disable zero counters if requested. */
                        if (!zero && !(val & mask))
                                continue;

                        grp->is_visible = NULL;
                }
                avail |= BIT(bit);
        }

        return avail;
}
EXPORT_SYMBOL_GPL(perf_msr_probe);