base.c

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/*
 *  This code maintains a list of active profiling data structures.
 *
 *    Copyright IBM Corp. 2009
 *    Author(s): Peter Oberparleiter <[email protected]>
 *
 *    Uses gcc-internal data definitions.
 *    Based on the gcov-kernel patch by:
 *       Hubertus Franke <[email protected]>
 *       Nigel Hinds <[email protected]>
 *       Rajan Ravindran <[email protected]>
 *       Peter Oberparleiter <[email protected]>
 *       Paul Larson
 */

#define pr_fmt(fmt) "gcov: " fmt

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

static struct gcov_info *gcov_info_head;
static int gcov_events_enabled;
static DEFINE_MUTEX(gcov_lock);

/*
 * __gcov_init is called by gcc-generated constructor code for each object
 * file compiled with -fprofile-arcs.
 */
void __gcov_init(struct gcov_info *info)
{
    static unsigned int gcov_version;

    mutex_lock(&gcov_lock);
    if (gcov_version == 0) {
        gcov_version = info->version;
        /*
         * Printing gcc's version magic may prove useful for debugging
         * incompatibility reports.
         */
        pr_info("version magic: 0x%x\n", gcov_version);
    }
    /*
     * Add new profiling data structure to list and inform event
     * listener.
     */
    info->next = gcov_info_head;
    gcov_info_head = info;
    if (gcov_events_enabled)
        gcov_event(GCOV_ADD, info);
    mutex_unlock(&gcov_lock);
}
EXPORT_SYMBOL(__gcov_init);

/*
 * These functions may be referenced by gcc-generated profiling code but serve
 * no function for kernel profiling.
 */
void __gcov_flush(void)
{
    /* Unused. */
}
EXPORT_SYMBOL(__gcov_flush);

void __gcov_merge_add(gcov_type *counters, unsigned int n_counters)
{
    /* Unused. */
}
EXPORT_SYMBOL(__gcov_merge_add);

void __gcov_merge_single(gcov_type *counters, unsigned int n_counters)
{
    /* Unused. */
}
EXPORT_SYMBOL(__gcov_merge_single);

void __gcov_merge_delta(gcov_type *counters, unsigned int n_counters)
{
    /* Unused. */
}
EXPORT_SYMBOL(__gcov_merge_delta);

void gcov_enable_events(void)
{
    struct gcov_info *info;

    mutex_lock(&gcov_lock);
    gcov_events_enabled = 1;
    /* Perform event callback for previously registered entries. */
    for (info = gcov_info_head; info; info = info->next)
        gcov_event(GCOV_ADD, info);
    mutex_unlock(&gcov_lock);
}

#ifdef CONFIG_MODULES
static inline int within(void *addr, void *start, unsigned long size)
{
    return ((addr >= start) && (addr < start + size));
}

/* 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;
    struct gcov_info *prev;

    if (event != MODULE_STATE_GOING)
        return NOTIFY_OK;
    mutex_lock(&gcov_lock);
    prev = NULL;
    /* Remove entries located in module from linked list. */
    for (info = gcov_info_head; info; info = info->next) {
        if (within(info, mod->module_core, mod->core_size)) {
            if (prev)
                prev->next = info->next;
            else
                gcov_info_head = info->next;
            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 */