// SPDX-License-Identifier: GPL-2.0
/*
 *  This code maintains a list of active profiling data structures.
 *
 *    Copyright IBM Corp. 2009
 *    Author(s): Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
 *
 *    Uses gcc-internal data definitions.
 *    Based on the gcov-kernel patch by:
 *               Hubertus Franke <frankeh@us.ibm.com>
 *               Nigel Hinds <nhinds@us.ibm.com>
 *               Rajan Ravindran <rajancr@us.ibm.com>
 *               Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
 *               Paul Larson
 */

#define pr_fmt(fmt)     "gcov: " fmt

#include <linux/init.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/sched.h>
#include "gcov.h"

int gcov_events_enabled;
DEFINE_MUTEX(gcov_lock);

/**
 * gcov_enable_events - enable event reporting through gcov_event()
 *
 * Turn on reporting of profiling data load/unload-events through the
 * gcov_event() callback. Also replay all previous events once. This function
 * is needed because some events are potentially generated too early for the
 * callback implementation to handle them initially.
 */
void gcov_enable_events(void)
{
        struct gcov_info *info = NULL;

        mutex_lock(&gcov_lock);
        gcov_events_enabled = 1;

        /* Perform event callback for previously registered entries. */
        while ((info = gcov_info_next(info))) {
                gcov_event(GCOV_ADD, info);
                cond_resched();
        }

        mutex_unlock(&gcov_lock);
}

/**
 * store_gcov_u32 - store 32 bit number in gcov format to buffer
 * @buffer: target buffer or NULL
 * @off: offset into the buffer
 * @v: value to be stored
 *
 * Number format defined by gcc: numbers are recorded in the 32 bit
 * unsigned binary form of the endianness of the machine generating the
 * file. Returns the number of bytes stored. If @buffer is %NULL, doesn't
 * store anything.
 */
size_t store_gcov_u32(void *buffer, size_t off, u32 v)
{
        u32 *data;

        if (buffer) {
                data = buffer + off;
                *data = v;
        }

        return sizeof(*data);
}

/**
 * store_gcov_u64 - store 64 bit number in gcov format to buffer
 * @buffer: target buffer or NULL
 * @off: offset into the buffer
 * @v: value to be stored
 *
 * Number format defined by gcc: numbers are recorded in the 32 bit
 * unsigned binary form of the endianness of the machine generating the
 * file. 64 bit numbers are stored as two 32 bit numbers, the low part
 * first. Returns the number of bytes stored. If @buffer is %NULL, doesn't store
 * anything.
 */
size_t store_gcov_u64(void *buffer, size_t off, u64 v)
{
        u32 *data;

        if (buffer) {
                data = buffer + off;

                data[0] = (v & 0xffffffffUL);
                data[1] = (v >> 32);
        }

        return sizeof(*data) * 2;
}

#ifdef CONFIG_MODULES
/* Update list and generate events when modules are unloaded. */
static int gcov_module_notifier(struct notifier_block *nb, unsigned long event,
                                void *data)
{
        struct module *mod = data;
        struct gcov_info *info = NULL;
        struct gcov_info *prev = NULL;

        if (event != MODULE_STATE_GOING)
                return NOTIFY_OK;
        mutex_lock(&gcov_lock);

        /* Remove entries located in module from linked list. */
        while ((info = gcov_info_next(info))) {
                if (gcov_info_within_module(info, mod)) {
                        gcov_info_unlink(prev, info);
                        if (gcov_events_enabled)
                                gcov_event(GCOV_REMOVE, info);
                } else
                        prev = info;
        }

        mutex_unlock(&gcov_lock);

        return NOTIFY_OK;
}

static struct notifier_block gcov_nb = {
        .notifier_call  = gcov_module_notifier,
};

static int __init gcov_init(void)
{
        return register_module_notifier(&gcov_nb);
}
device_initcall(gcov_init);
#endif /* CONFIG_MODULES */