LXR linux/kernel/gcov/base.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 *  This code maintains a list of active profiling data structures.
   4 *
   5 *    Copyright IBM Corp. 2009
   6 *    Author(s): Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
   7 *
   8 *    Uses gcc-internal data definitions.
   9 *    Based on the gcov-kernel patch by:
  10 *               Hubertus Franke <frankeh@us.ibm.com>
  11 *               Nigel Hinds <nhinds@us.ibm.com>
  12 *               Rajan Ravindran <rajancr@us.ibm.com>
  13 *               Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
  14 *               Paul Larson
  15 */
  16
  17#define pr_fmt(fmt)     "gcov: " fmt
  18
  19#include <linux/init.h>
  20#include <linux/module.h>
  21#include <linux/mutex.h>
  22#include <linux/sched.h>
  23#include "gcov.h"
  24
  25int gcov_events_enabled;
  26DEFINE_MUTEX(gcov_lock);
  27
  28/**
  29 * gcov_enable_events - enable event reporting through gcov_event()
  30 *
  31 * Turn on reporting of profiling data load/unload-events through the
  32 * gcov_event() callback. Also replay all previous events once. This function
  33 * is needed because some events are potentially generated too early for the
  34 * callback implementation to handle them initially.
  35 */
  36void gcov_enable_events(void)
  37{
  38        struct gcov_info *info = NULL;
  39
  40        mutex_lock(&gcov_lock);
  41        gcov_events_enabled = 1;
  42
  43        /* Perform event callback for previously registered entries. */
  44        while ((info = gcov_info_next(info))) {
  45                gcov_event(GCOV_ADD, info);
  46                cond_resched();
  47        }
  48
  49        mutex_unlock(&gcov_lock);
  50}
  51
  52/**
  53 * store_gcov_u32 - store 32 bit number in gcov format to buffer
  54 * @buffer: target buffer or NULL
  55 * @off: offset into the buffer
  56 * @v: value to be stored
  57 *
  58 * Number format defined by gcc: numbers are recorded in the 32 bit
  59 * unsigned binary form of the endianness of the machine generating the
  60 * file. Returns the number of bytes stored. If @buffer is %NULL, doesn't
  61 * store anything.
  62 */
  63size_t store_gcov_u32(void *buffer, size_t off, u32 v)
  64{
  65        u32 *data;
  66
  67        if (buffer) {
  68                data = buffer + off;
  69                *data = v;
  70        }
  71
  72        return sizeof(*data);
  73}
  74
  75/**
  76 * store_gcov_u64 - store 64 bit number in gcov format to buffer
  77 * @buffer: target buffer or NULL
  78 * @off: offset into the buffer
  79 * @v: value to be stored
  80 *
  81 * Number format defined by gcc: numbers are recorded in the 32 bit
  82 * unsigned binary form of the endianness of the machine generating the
  83 * file. 64 bit numbers are stored as two 32 bit numbers, the low part
  84 * first. Returns the number of bytes stored. If @buffer is %NULL, doesn't store
  85 * anything.
  86 */
  87size_t store_gcov_u64(void *buffer, size_t off, u64 v)
  88{
  89        u32 *data;
  90
  91        if (buffer) {
  92                data = buffer + off;
  93
  94                data[0] = (v & 0xffffffffUL);
  95                data[1] = (v >> 32);
  96        }
  97
  98        return sizeof(*data) * 2;
  99}
 100
 101#ifdef CONFIG_MODULES
 102/* Update list and generate events when modules are unloaded. */
 103static int gcov_module_notifier(struct notifier_block *nb, unsigned long event,
 104                                void *data)
 105{
 106        struct module *mod = data;
 107        struct gcov_info *info = NULL;
 108        struct gcov_info *prev = NULL;
 109
 110        if (event != MODULE_STATE_GOING)
 111                return NOTIFY_OK;
 112        mutex_lock(&gcov_lock);
 113
 114        /* Remove entries located in module from linked list. */
 115        while ((info = gcov_info_next(info))) {
 116                if (gcov_info_within_module(info, mod)) {
 117                        gcov_info_unlink(prev, info);
 118                        if (gcov_events_enabled)
 119                                gcov_event(GCOV_REMOVE, info);
 120                } else
 121                        prev = info;
 122        }
 123
 124        mutex_unlock(&gcov_lock);
 125
 126        return NOTIFY_OK;
 127}
 128
 129static struct notifier_block gcov_nb = {
 130        .notifier_call  = gcov_module_notifier,
 131};
 132
 133static int __init gcov_init(void)
 134{
 135        return register_module_notifier(&gcov_nb);
 136}
 137device_initcall(gcov_init);
 138#endif /* CONFIG_MODULES */
 139