FreeBSD/Linux Kernel Cross Reference
sys/gnu/gcov/gcov_fs.c

     // SPDX-License-Identifier: GPL-2.0
     // This program is free software; you can redistribute it and/or
     // modify it under the terms of the GNU General Public License
     // as published by the Free Software Foundation; version 2.
     //
     // This program is distributed in the hope that it will be useful,
     // but WITHOUT ANY WARRANTY; without even the implied warranty of
     // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     // GNU General Public License for more details.
    //
    // You should have received a copy of the GNU General Public License
    // along with this program; if not, write to the Free Software
    // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
    // 02110-1301, USA.
    /*
     *  This code exports profiling data as debugfs files to userspace.
     *
     *    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
     *               Yi CDL Yang
     */
    
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include <sys/types.h>
    #include <sys/systm.h>
    #include <sys/param.h>
    #include <sys/sbuf.h>
    
    #include <sys/queue.h>
    #include <sys/linker.h>
    #include <sys/module.h>
    #include <sys/eventhandler.h>
    #include <sys/kernel.h>
    #include <sys/malloc.h>
    #include <sys/syslog.h>
    #include <sys/proc.h>
    #include <sys/sched.h>
    #include <sys/syslog.h>
    #include <sys/sysctl.h>
    #include <linux/debugfs.h>
    
    #include <gnu/gcov/gcov.h>
    #include <sys/queue.h>
    
    extern int gcov_events_enabled;
    static int gcov_persist;
    static struct mtx gcov_mtx;
    MTX_SYSINIT(gcov_init, &gcov_mtx, "gcov_mtx", MTX_DEF);
    MALLOC_DEFINE(M_GCOV, "gcov", "gcov");
    
    void __gcov_init(struct gcov_info *info);
    void __gcov_flush(void);
    void __gcov_merge_add(gcov_type *counters, unsigned int n_counters);
    void __gcov_merge_single(gcov_type *counters, unsigned int n_counters);
    void __gcov_merge_delta(gcov_type *counters, unsigned int n_counters);
    void __gcov_merge_ior(gcov_type *counters, unsigned int n_counters);
    void __gcov_merge_time_profile(gcov_type *counters, unsigned int n_counters);
    void __gcov_merge_icall_topn(gcov_type *counters, unsigned int n_counters);
    void __gcov_exit(void);
    
    static void gcov_event(enum gcov_action action, struct gcov_info *info);
    
    
    /*
     * Private copy taken from libc
     */
    static char *
    (basename)(char *path)
    {
            char *ptr;
    
            /*
             * If path is a null pointer or points to an empty string,
             * basename() shall return a pointer to the string ".".
             */
            if (path == NULL || *path == '\0')
                    return (__DECONST(char *, "."));
    
            /* Find end of last pathname component and null terminate it. */
            ptr = path + strlen(path);
            while (ptr > path + 1 && *(ptr - 1) == '/')
                    --ptr;
            *ptr-- = '\0';
    
            /* Find beginning of last pathname component. */
            while (ptr > path && *(ptr - 1) != '/')
                    --ptr;
            return (ptr);
   }
   
   /*
    * __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;
   
           mtx_lock(&gcov_mtx);
           if (gcov_version == 0) {
                   gcov_version = gcov_info_version(info);
                   /*
                    * Printing gcc's version magic may prove useful for debugging
                    * incompatibility reports.
                    */
                   log(LOG_INFO, "version magic: 0x%x\n", gcov_version);
           }
           /*
            * Add new profiling data structure to list and inform event
            * listener.
            */
           gcov_info_link(info);
           if (gcov_events_enabled)
                   gcov_event(GCOV_ADD, info);
           mtx_unlock(&gcov_mtx);
   }
   
   /*
    * These functions may be referenced by gcc-generated profiling code but serve
    * no function for kernel profiling.
    */
   void
   __gcov_flush(void)
   {
           /* Unused. */
   }
   
   void
   __gcov_merge_add(gcov_type *counters, unsigned int n_counters)
   {
           /* Unused. */
   }
   
   void
   __gcov_merge_single(gcov_type *counters, unsigned int n_counters)
   {
           /* Unused. */
   }
   
   void
   __gcov_merge_delta(gcov_type *counters, unsigned int n_counters)
   {
           /* Unused. */
   }
   
   void
   __gcov_merge_ior(gcov_type *counters, unsigned int n_counters)
   {
           /* Unused. */
   }
   
   void
   __gcov_merge_time_profile(gcov_type *counters, unsigned int n_counters)
   {
           /* Unused. */
   }
   
   void
   __gcov_merge_icall_topn(gcov_type *counters, unsigned int n_counters)
   {
           /* Unused. */
   }
   
   void
   __gcov_exit(void)
   {
           /* Unused. */
   }
   
   
   /**
    * struct gcov_node - represents a debugfs entry
    * @entry: list entry for parent's child node list
    * @children: child nodes
    * @all_entry: list entry for list of all nodes
    * @parent: parent node
    * @loaded_info: array of pointers to profiling data sets for loaded object
    *   files.
    * @num_loaded: number of profiling data sets for loaded object files.
    * @unloaded_info: accumulated copy of profiling data sets for unloaded
    *   object files. Used only when gcov_persist=1.
    * @dentry: main debugfs entry, either a directory or data file
    * @links: associated symbolic links
    * @name: data file basename
    *
    * struct gcov_node represents an entity within the gcov/ subdirectory
    * of debugfs. There are directory and data file nodes. The latter represent
    * the actual synthesized data file plus any associated symbolic links which
    * are needed by the gcov tool to work correctly.
    */
   struct gcov_node {
           LIST_ENTRY(gcov_node) children_entry;
           LIST_ENTRY(gcov_node) all_entry;
           struct {
                   struct gcov_node *lh_first;
           } children;
           struct gcov_node *parent;
           struct gcov_info **loaded_info;
           struct gcov_info *unloaded_info;
           struct dentry *dentry;
           struct dentry **links;
           int num_loaded;
           char name[0];
   };
   
   #ifdef notyet
   static const char objtree[] = OBJTREE;
   static const char srctree[] = SRCTREE;
   #else
   static const char objtree[] = "";
   static const char srctree[] = "";
   #endif
   static struct gcov_node root_node;
   static struct {
           struct gcov_node *lh_first;
   } all_head;
   static struct mtx node_lock;
   MTX_SYSINIT(node_init, &node_lock, "node_lock", MTX_DEF);
   static void remove_node(struct gcov_node *node);
   
   /*
    * seq_file.start() implementation for gcov data files. Note that the
    * gcov_iterator interface is designed to be more restrictive than seq_file
    * (no start from arbitrary position, etc.), to simplify the iterator
    * implementation.
    */
   static void *
   gcov_seq_start(struct seq_file *seq, off_t *pos)
   {
           off_t i;
   
           gcov_iter_start(seq->private);
           for (i = 0; i < *pos; i++) {
                   if (gcov_iter_next(seq->private))
                           return NULL;
           }
           return seq->private;
   }
   
   /* seq_file.next() implementation for gcov data files. */
   static void *
   gcov_seq_next(struct seq_file *seq, void *data, off_t *pos)
   {
           struct gcov_iterator *iter = data;
   
           if (gcov_iter_next(iter))
                   return NULL;
           (*pos)++;
   
           return iter;
   }
   
   /* seq_file.show() implementation for gcov data files. */
   static int
   gcov_seq_show(struct seq_file *seq, void *data)
   {
           struct gcov_iterator *iter = data;
   
           if (gcov_iter_write(iter, seq->buf))
                   return (-EINVAL);
           return (0);
   }
   
   static void
   gcov_seq_stop(struct seq_file *seq, void *data)
   {
           /* Unused. */
   }
   
   static const struct seq_operations gcov_seq_ops = {
           .start  = gcov_seq_start,
           .next   = gcov_seq_next,
           .show   = gcov_seq_show,
           .stop   = gcov_seq_stop,
   };
   
   /*
    * Return a profiling data set associated with the given node. This is
    * either a data set for a loaded object file or a data set copy in case
    * all associated object files have been unloaded.
    */
   static struct gcov_info *
   get_node_info(struct gcov_node *node)
   {
           if (node->num_loaded > 0)
                   return (node->loaded_info[0]);
   
           return (node->unloaded_info);
   }
   
   /*
    * Return a newly allocated profiling data set which contains the sum of
    * all profiling data associated with the given node.
    */
   static struct gcov_info *
   get_accumulated_info(struct gcov_node *node)
   {
           struct gcov_info *info;
           int i = 0;
   
           if (node->unloaded_info)
                   info = gcov_info_dup(node->unloaded_info);
           else
                   info = gcov_info_dup(node->loaded_info[i++]);
           if (info == NULL)
                   return (NULL);
           for (; i < node->num_loaded; i++)
                   gcov_info_add(info, node->loaded_info[i]);
   
           return (info);
   }
   
   /*
    * open() implementation for gcov data files. Create a copy of the profiling
    * data set and initialize the iterator and seq_file interface.
    */
   static int
   gcov_seq_open(struct inode *inode, struct file *file)
   {
           struct gcov_node *node = inode->i_private;
           struct gcov_iterator *iter;
           struct seq_file *seq;
           struct gcov_info *info;
           int rc = -ENOMEM;
   
           mtx_lock(&node_lock);
           /*
            * Read from a profiling data copy to minimize reference tracking
            * complexity and concurrent access and to keep accumulating multiple
            * profiling data sets associated with one node simple.
            */
           info = get_accumulated_info(node);
           if (info == NULL)
                   goto out_unlock;
           iter = gcov_iter_new(info);
           if (iter == NULL)
                   goto err_free_info;
           rc = seq_open(file, &gcov_seq_ops);
           if (rc)
                   goto err_free_iter_info;
           seq = file->private_data;
           seq->private = iter;
   out_unlock:
           mtx_unlock(&node_lock);
           return (rc);
   
   err_free_iter_info:
           gcov_iter_free(iter);
   err_free_info:
           gcov_info_free(info);
           goto out_unlock;
   }
   
   /*
    * release() implementation for gcov data files. Release resources allocated
    * by open().
    */
   static int
   gcov_seq_release(struct inode *inode, struct file *file)
   {
           struct gcov_iterator *iter;
           struct gcov_info *info;
           struct seq_file *seq;
   
           seq = file->private_data;
           iter = seq->private;
           info = gcov_iter_get_info(iter);
           gcov_iter_free(iter);
           gcov_info_free(info);
           seq_release(inode, file);
   
           return (0);
   }
   
   /*
    * Find a node by the associated data file name. Needs to be called with
    * node_lock held.
    */
   static struct gcov_node *
   get_node_by_name(const char *name)
   {
           struct gcov_node *node;
           struct gcov_info *info;
   
           LIST_FOREACH(node, &all_head, all_entry) {
                   info = get_node_info(node);
                   if (info && (strcmp(gcov_info_filename(info), name) == 0))
                           return (node);
           }
   
           return (NULL);
   }
   
   /*
    * Reset all profiling data associated with the specified node.
    */
   static void
   reset_node(struct gcov_node *node)
   {
           int i;
   
           if (node->unloaded_info)
                   gcov_info_reset(node->unloaded_info);
           for (i = 0; i < node->num_loaded; i++)
                   gcov_info_reset(node->loaded_info[i]);
   }
   
   void
   gcov_stats_reset(void)
   {
           struct gcov_node *node;
   
           mtx_lock(&node_lock);
    restart:
           LIST_FOREACH(node, &all_head, all_entry) {
                   if (node->num_loaded > 0)
                           reset_node(node);
                   else if (LIST_EMPTY(&node->children)) {
                           remove_node(node);
                           goto restart;
                   }
           }
           mtx_unlock(&node_lock);
   }
   
   /*
    * write() implementation for gcov data files. Reset profiling data for the
    * corresponding file. If all associated object files have been unloaded,
    * remove the debug fs node as well.
    */
   static ssize_t
   gcov_seq_write(struct file *file, const char *addr, size_t len, off_t *pos)
   {
           struct seq_file *seq;
           struct gcov_info *info;
           struct gcov_node *node;
   
           seq = file->private_data;
           info = gcov_iter_get_info(seq->private);
           mtx_lock(&node_lock);
           node = get_node_by_name(gcov_info_filename(info));
           if (node) {
                   /* Reset counts or remove node for unloaded modules. */
                   if (node->num_loaded == 0)
                           remove_node(node);
                   else
                           reset_node(node);
           }
           /* Reset counts for open file. */
           gcov_info_reset(info);
           mtx_unlock(&node_lock);
   
           return (len);
   }
   
   /*
    * Given a string <path> representing a file path of format:
    *   path/to/file.gcda
    * construct and return a new string:
    *   <dir/>path/to/file.<ext>
    */
   static char *
   link_target(const char *dir, const char *path, const char *ext)
   {
           char *target;
           char *old_ext;
           char *copy;
   
           copy = strdup_flags(path, M_GCOV, M_NOWAIT);
           if (!copy)
                   return (NULL);
           old_ext = strrchr(copy, '.');
           if (old_ext)
                   *old_ext = '\0';
           target = NULL;
           if (dir)
                   asprintf(&target, M_GCOV, "%s/%s.%s", dir, copy, ext);
           else
                   asprintf(&target, M_GCOV, "%s.%s", copy, ext);
           free(copy, M_GCOV);
   
           return (target);
   }
   
   /*
    * Construct a string representing the symbolic link target for the given
    * gcov data file name and link type. Depending on the link type and the
    * location of the data file, the link target can either point to a
    * subdirectory of srctree, objtree or in an external location.
    */
   static char *
   get_link_target(const char *filename, const struct gcov_link *ext)
   {
           const char *rel;
           char *result;
   
           if (strncmp(filename, objtree, strlen(objtree)) == 0) {
                   rel = filename + strlen(objtree) + 1;
                   if (ext->dir == SRC_TREE)
                           result = link_target(srctree, rel, ext->ext);
                   else
                           result = link_target(objtree, rel, ext->ext);
           } else {
                   /* External compilation. */
                   result = link_target(NULL, filename, ext->ext);
           }
   
           return (result);
   }
   
   #define SKEW_PREFIX     ".tmp_"
   
   /*
    * For a filename .tmp_filename.ext return filename.ext. Needed to compensate
    * for filename skewing caused by the mod-versioning mechanism.
    */
   static const char *
   deskew(const char *basename)
   {
           if (strncmp(basename, SKEW_PREFIX, sizeof(SKEW_PREFIX) - 1) == 0)
                   return (basename + sizeof(SKEW_PREFIX) - 1);
           return (basename);
   }
   
   /*
    * Create links to additional files (usually .c and .gcno files) which the
    * gcov tool expects to find in the same directory as the gcov data file.
    */
   static void
   add_links(struct gcov_node *node, struct dentry *parent)
   {
           const char *path_basename;
           char *target;
           int num;
           int i;
   
           for (num = 0; gcov_link[num].ext; num++)
                   /* Nothing. */;
           node->links = malloc((num*sizeof(struct dentry *)), M_GCOV, M_NOWAIT|M_ZERO);
           if (node->links == NULL)
                   return;
           for (i = 0; i < num; i++) {
                   target = get_link_target(
                                   gcov_info_filename(get_node_info(node)),
                                   &gcov_link[i]);
                   if (target == NULL)
                           goto out_err;
                   path_basename = basename(target);
                   if (path_basename == target)
                           goto out_err;
                   node->links[i] = debugfs_create_symlink(deskew(path_basename),
                                                           parent, target);
                   if (!node->links[i])
                           goto out_err;
                   free(target, M_GCOV);
           }
   
           return;
   out_err:
           free(target, M_GCOV);
           while (i-- > 0)
                   debugfs_remove(node->links[i]);
           free(node->links, M_GCOV);
           node->links = NULL;
   }
   
   static const struct file_operations gcov_data_fops = {
           .open           = gcov_seq_open,
           .release        = gcov_seq_release,
           .read           = seq_read,
           .llseek         = seq_lseek,
           .write          = gcov_seq_write,
   };
   
   /* Basic initialization of a new node. */
   static void
   init_node(struct gcov_node *node, struct gcov_info *info,
      const char *name, struct gcov_node *parent)
   {
           LIST_INIT(&node->children);
           if (node->loaded_info) {
                   node->loaded_info[0] = info;
                   node->num_loaded = 1;
           }
           node->parent = parent;
           if (name)
                   strcpy(node->name, name);
   }
   
   /*
    * Create a new node and associated debugfs entry. Needs to be called with
    * node_lock held.
    */
   static struct gcov_node *
   new_node(struct gcov_node *parent, struct gcov_info *info, const char *name)
   {
           struct gcov_node *node;
   
           node = malloc(sizeof(struct gcov_node) + strlen(name) + 1, M_GCOV, M_NOWAIT|M_ZERO);
           if (!node)
                   goto err_nomem;
           if (info) {
                   node->loaded_info = malloc(sizeof(struct gcov_info *), M_GCOV, M_NOWAIT|M_ZERO);
                   if (!node->loaded_info)
                           goto err_nomem;
           }
           init_node(node, info, name, parent);
           /* Differentiate between gcov data file nodes and directory nodes. */
           if (info) {
                   node->dentry = debugfs_create_file(deskew(node->name), 0600,
                                           parent->dentry, node, &gcov_data_fops);
           } else
                   node->dentry = debugfs_create_dir(node->name, parent->dentry);
           if (!node->dentry) {
                   log(LOG_WARNING, "could not create file\n");
                   free(node, M_GCOV);
                   return NULL;
           }
           if (info)
                   add_links(node, parent->dentry);
           LIST_INSERT_HEAD(&parent->children, node, children_entry);
           LIST_INSERT_HEAD(&all_head, node, all_entry);
   
           return (node);
   
   err_nomem:
           free(node, M_GCOV);
           log(LOG_WARNING, "out of memory\n");
           return NULL;
   }
   
   /* Remove symbolic links associated with node. */
   static void
   remove_links(struct gcov_node *node)
   {
   
           if (node->links == NULL)
                   return;
           for (int i = 0; gcov_link[i].ext; i++)
                   debugfs_remove(node->links[i]);
           free(node->links, M_GCOV);
           node->links = NULL;
   }
   
   /*
    * Remove node from all lists and debugfs and release associated resources.
    * Needs to be called with node_lock held.
    */
   static void
   release_node(struct gcov_node *node)
   {
           LIST_REMOVE(node, children_entry);
           LIST_REMOVE(node, all_entry);
           debugfs_remove(node->dentry);
           remove_links(node);
           free(node->loaded_info, M_GCOV);
           if (node->unloaded_info)
                   gcov_info_free(node->unloaded_info);
           free(node, M_GCOV);
   }
   
   /* Release node and empty parents. Needs to be called with node_lock held. */
   static void
   remove_node(struct gcov_node *node)
   {
           struct gcov_node *parent;
   
           while ((node != &root_node) && LIST_EMPTY(&node->children)) {
                   parent = node->parent;
                   release_node(node);
                   node = parent;
           }
   }
   
   /*
    * Find child node with given basename. Needs to be called with node_lock
    * held.
    */
   static struct gcov_node *
   get_child_by_name(struct gcov_node *parent, const char *name)
   {
           struct gcov_node *node;
   
           LIST_FOREACH(node, &parent->children, children_entry) {
                   if (strcmp(node->name, name) == 0)
                           return (node);
           }
   
           return (NULL);
   }
   
   /*
    * Create a node for a given profiling data set and add it to all lists and
    * debugfs. Needs to be called with node_lock held.
    */
   static void
   add_node(struct gcov_info *info)
   {
           char *filename;
           char *curr;
           char *next;
           struct gcov_node *parent;
           struct gcov_node *node;
   
           filename = strdup_flags(gcov_info_filename(info), M_GCOV, M_NOWAIT);
           if (filename == NULL)
                   return;
           parent = &root_node;
           /* Create directory nodes along the path. */
           for (curr = filename; (next = strchr(curr, '/')); curr = next + 1) {
                   if (curr == next)
                           continue;
                   *next = 0;
                   if (strcmp(curr, ".") == 0)
                           continue;
                   if (strcmp(curr, "..") == 0) {
                           if (!parent->parent)
                                   goto err_remove;
                           parent = parent->parent;
                           continue;
                   }
                   node = get_child_by_name(parent, curr);
                   if (!node) {
                           node = new_node(parent, NULL, curr);
                           if (!node)
                                   goto err_remove;
                   }
                   parent = node;
           }
           /* Create file node. */
           node = new_node(parent, info, curr);
           if (!node)
                   goto err_remove;
   out:
           free(filename, M_GCOV);
           return;
   
   err_remove:
           remove_node(parent);
           goto out;
   }
   
   /*
    * Associate a profiling data set with an existing node. Needs to be called
    * with node_lock held.
    */
   static void
   add_info(struct gcov_node *node, struct gcov_info *info)
   {
           struct gcov_info **loaded_info;
           int num = node->num_loaded;
   
           /*
            * Prepare new array. This is done first to simplify cleanup in
            * case the new data set is incompatible, the node only contains
            * unloaded data sets and there's not enough memory for the array.
            */
           loaded_info = malloc((num + 1)* sizeof(struct gcov_info *), M_GCOV, M_NOWAIT|M_ZERO);
           if (!loaded_info) {
                   log(LOG_WARNING, "could not add '%s' (out of memory)\n",
                           gcov_info_filename(info));
                   return;
           }
           memcpy(loaded_info, node->loaded_info,
                  num * sizeof(struct gcov_info *));
           loaded_info[num] = info;
           /* Check if the new data set is compatible. */
           if (num == 0) {
                   /*
                    * A module was unloaded, modified and reloaded. The new
                    * data set replaces the copy of the last one.
                    */
                   if (!gcov_info_is_compatible(node->unloaded_info, info)) {
                           log(LOG_WARNING, "discarding saved data for %s "
                                   "(incompatible version)\n",
                                   gcov_info_filename(info));
                           gcov_info_free(node->unloaded_info);
                           node->unloaded_info = NULL;
                   }
           } else {
                   /*
                    * Two different versions of the same object file are loaded.
                    * The initial one takes precedence.
                    */
                   if (!gcov_info_is_compatible(node->loaded_info[0], info)) {
                           log(LOG_WARNING, "could not add '%s' (incompatible "
                                   "version)\n", gcov_info_filename(info));
                           free(loaded_info, M_GCOV);
                           return;
                   }
           }
           /* Overwrite previous array. */
           free(node->loaded_info, M_GCOV);
           node->loaded_info = loaded_info;
           node->num_loaded = num + 1;
   }
   
   /*
    * Return the index of a profiling data set associated with a node.
    */
   static int
   get_info_index(struct gcov_node *node, struct gcov_info *info)
   {
           int i;
   
           for (i = 0; i < node->num_loaded; i++) {
                   if (node->loaded_info[i] == info)
                           return (i);
           }
           return (ENOENT);
   }
   
   /*
    * Save the data of a profiling data set which is being unloaded.
    */
   static void
   save_info(struct gcov_node *node, struct gcov_info *info)
   {
           if (node->unloaded_info)
                   gcov_info_add(node->unloaded_info, info);
           else {
                   node->unloaded_info = gcov_info_dup(info);
                   if (!node->unloaded_info) {
                           log(LOG_WARNING, "could not save data for '%s' "
                                   "(out of memory)\n",
                                   gcov_info_filename(info));
                   }
           }
   }
   
   /*
    * Disassociate a profiling data set from a node. Needs to be called with
    * node_lock held.
    */
   static void
   remove_info(struct gcov_node *node, struct gcov_info *info)
   {
           int i;
   
           i = get_info_index(node, info);
           if (i < 0) {
                   log(LOG_WARNING, "could not remove '%s' (not found)\n",
                           gcov_info_filename(info));
                   return;
           }
           if (gcov_persist)
                   save_info(node, info);
           /* Shrink array. */
           node->loaded_info[i] = node->loaded_info[node->num_loaded - 1];
           node->num_loaded--;
           if (node->num_loaded > 0)
                   return;
           /* Last loaded data set was removed. */
           free(node->loaded_info, M_GCOV);
           node->loaded_info = NULL;
           node->num_loaded = 0;
           if (!node->unloaded_info)
                   remove_node(node);
   }
   
   /*
    * Callback to create/remove profiling files when code compiled with
    * -fprofile-arcs is loaded/unloaded.
    */
   static void
   gcov_event(enum gcov_action action, struct gcov_info *info)
   {
           struct gcov_node *node;
   
           mtx_lock(&node_lock);
           node = get_node_by_name(gcov_info_filename(info));
           switch (action) {
           case GCOV_ADD:
                   if (node)
                           add_info(node, info);
                   else
                           add_node(info);
                   break;
           case GCOV_REMOVE:
                   if (node)
                           remove_info(node, info);
                   else {
                           log(LOG_WARNING, "could not remove '%s' (not found)\n",
                                   gcov_info_filename(info));
                   }
                   break;
           }
           mtx_unlock(&node_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;
           int count;
   
           mtx_lock(&gcov_mtx);
           count = 0;
   
           /* Perform event callback for previously registered entries. */
           while ((info = gcov_info_next(info))) {
                   gcov_event(GCOV_ADD, info);
                   sched_relinquish(curthread);
                   count++;
           }
   
           mtx_unlock(&gcov_mtx);
           printf("%s found %d events\n", __func__, count);
   }
   
   /* Update list and generate events when modules are unloaded. */
   void
   gcov_module_unload(void *arg __unused, module_t mod)
   {
           struct gcov_info *info = NULL;
           struct gcov_info *prev = NULL;
   
           mtx_lock(&gcov_mtx );
   
           /* Remove entries located in module from linked list. */
           while ((info = gcov_info_next(info))) {
                   if (within_module((vm_offset_t)info, mod)) {
                           gcov_info_unlink(prev, info);
                           if (gcov_events_enabled)
                                   gcov_event(GCOV_REMOVE, info);
                   } else
                           prev = info;
           }
   
           mtx_unlock(&gcov_mtx);
   }
   
   void
   gcov_fs_init(void)
   {
           init_node(&root_node, NULL, NULL, NULL);
           root_node.dentry = debugfs_create_dir("gcov", NULL);
   }

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