mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-23 09:19:51 +00:00
674 lines
16 KiB
C
674 lines
16 KiB
C
![]() |
/*
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* This code exports profiling data as debugfs files to userspace.
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*
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* Copyright IBM Corp. 2009
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* Author(s): Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
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*
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* Uses gcc-internal data definitions.
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* Based on the gcov-kernel patch by:
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* Hubertus Franke <frankeh@us.ibm.com>
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* Nigel Hinds <nhinds@us.ibm.com>
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* Rajan Ravindran <rajancr@us.ibm.com>
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* Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
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* Paul Larson
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* Yi CDL Yang
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*/
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#define pr_fmt(fmt) "gcov: " fmt
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/debugfs.h>
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#include <linux/fs.h>
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#include <linux/list.h>
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#include <linux/string.h>
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#include <linux/slab.h>
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#include <linux/mutex.h>
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#include <linux/seq_file.h>
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#include "gcov.h"
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/**
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* struct gcov_node - represents a debugfs entry
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* @list: list head for child node list
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* @children: child nodes
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* @all: list head for list of all nodes
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* @parent: parent node
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* @info: associated profiling data structure if not a directory
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* @ghost: when an object file containing profiling data is unloaded we keep a
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* copy of the profiling data here to allow collecting coverage data
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* for cleanup code. Such a node is called a "ghost".
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* @dentry: main debugfs entry, either a directory or data file
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* @links: associated symbolic links
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* @name: data file basename
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*
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* struct gcov_node represents an entity within the gcov/ subdirectory
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* of debugfs. There are directory and data file nodes. The latter represent
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* the actual synthesized data file plus any associated symbolic links which
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* are needed by the gcov tool to work correctly.
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*/
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struct gcov_node {
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struct list_head list;
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struct list_head children;
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struct list_head all;
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struct gcov_node *parent;
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struct gcov_info *info;
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struct gcov_info *ghost;
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struct dentry *dentry;
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struct dentry **links;
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char name[0];
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};
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static const char objtree[] = OBJTREE;
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static const char srctree[] = SRCTREE;
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static struct gcov_node root_node;
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static struct dentry *reset_dentry;
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static LIST_HEAD(all_head);
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static DEFINE_MUTEX(node_lock);
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/* If non-zero, keep copies of profiling data for unloaded modules. */
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static int gcov_persist = 1;
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static int __init gcov_persist_setup(char *str)
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{
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unsigned long val;
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if (strict_strtoul(str, 0, &val)) {
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pr_warning("invalid gcov_persist parameter '%s'\n", str);
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return 0;
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}
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gcov_persist = val;
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pr_info("setting gcov_persist to %d\n", gcov_persist);
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return 1;
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}
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__setup("gcov_persist=", gcov_persist_setup);
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/*
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* seq_file.start() implementation for gcov data files. Note that the
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* gcov_iterator interface is designed to be more restrictive than seq_file
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* (no start from arbitrary position, etc.), to simplify the iterator
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* implementation.
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*/
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static void *gcov_seq_start(struct seq_file *seq, loff_t *pos)
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{
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loff_t i;
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gcov_iter_start(seq->private);
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for (i = 0; i < *pos; i++) {
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if (gcov_iter_next(seq->private))
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return NULL;
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}
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return seq->private;
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}
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/* seq_file.next() implementation for gcov data files. */
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static void *gcov_seq_next(struct seq_file *seq, void *data, loff_t *pos)
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{
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struct gcov_iterator *iter = data;
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if (gcov_iter_next(iter))
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return NULL;
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(*pos)++;
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return iter;
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}
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/* seq_file.show() implementation for gcov data files. */
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static int gcov_seq_show(struct seq_file *seq, void *data)
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{
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struct gcov_iterator *iter = data;
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if (gcov_iter_write(iter, seq))
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return -EINVAL;
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return 0;
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}
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static void gcov_seq_stop(struct seq_file *seq, void *data)
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{
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/* Unused. */
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}
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static const struct seq_operations gcov_seq_ops = {
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.start = gcov_seq_start,
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.next = gcov_seq_next,
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.show = gcov_seq_show,
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.stop = gcov_seq_stop,
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};
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/*
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* Return the profiling data set for a given node. This can either be the
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* original profiling data structure or a duplicate (also called "ghost")
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* in case the associated object file has been unloaded.
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*/
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static struct gcov_info *get_node_info(struct gcov_node *node)
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{
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if (node->info)
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return node->info;
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return node->ghost;
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}
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/*
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* open() implementation for gcov data files. Create a copy of the profiling
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* data set and initialize the iterator and seq_file interface.
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*/
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static int gcov_seq_open(struct inode *inode, struct file *file)
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{
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struct gcov_node *node = inode->i_private;
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struct gcov_iterator *iter;
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struct seq_file *seq;
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struct gcov_info *info;
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int rc = -ENOMEM;
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mutex_lock(&node_lock);
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/*
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* Read from a profiling data copy to minimize reference tracking
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* complexity and concurrent access.
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*/
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info = gcov_info_dup(get_node_info(node));
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if (!info)
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goto out_unlock;
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iter = gcov_iter_new(info);
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if (!iter)
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goto err_free_info;
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rc = seq_open(file, &gcov_seq_ops);
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if (rc)
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goto err_free_iter_info;
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seq = file->private_data;
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seq->private = iter;
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out_unlock:
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mutex_unlock(&node_lock);
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return rc;
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err_free_iter_info:
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gcov_iter_free(iter);
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err_free_info:
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gcov_info_free(info);
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goto out_unlock;
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}
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/*
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* release() implementation for gcov data files. Release resources allocated
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* by open().
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*/
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static int gcov_seq_release(struct inode *inode, struct file *file)
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{
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struct gcov_iterator *iter;
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struct gcov_info *info;
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struct seq_file *seq;
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seq = file->private_data;
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iter = seq->private;
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info = gcov_iter_get_info(iter);
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gcov_iter_free(iter);
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gcov_info_free(info);
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seq_release(inode, file);
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return 0;
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}
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/*
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* Find a node by the associated data file name. Needs to be called with
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* node_lock held.
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*/
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static struct gcov_node *get_node_by_name(const char *name)
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{
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struct gcov_node *node;
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struct gcov_info *info;
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list_for_each_entry(node, &all_head, all) {
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info = get_node_info(node);
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if (info && (strcmp(info->filename, name) == 0))
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return node;
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}
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return NULL;
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}
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static void remove_node(struct gcov_node *node);
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/*
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* write() implementation for gcov data files. Reset profiling data for the
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* associated file. If the object file has been unloaded (i.e. this is
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* a "ghost" node), remove the debug fs node as well.
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*/
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static ssize_t gcov_seq_write(struct file *file, const char __user *addr,
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size_t len, loff_t *pos)
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{
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struct seq_file *seq;
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struct gcov_info *info;
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struct gcov_node *node;
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seq = file->private_data;
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info = gcov_iter_get_info(seq->private);
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mutex_lock(&node_lock);
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node = get_node_by_name(info->filename);
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if (node) {
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/* Reset counts or remove node for unloaded modules. */
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if (node->ghost)
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remove_node(node);
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else
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gcov_info_reset(node->info);
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}
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/* Reset counts for open file. */
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gcov_info_reset(info);
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mutex_unlock(&node_lock);
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return len;
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}
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/*
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* Given a string <path> representing a file path of format:
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* path/to/file.gcda
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* construct and return a new string:
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* <dir/>path/to/file.<ext>
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*/
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static char *link_target(const char *dir, const char *path, const char *ext)
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{
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char *target;
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char *old_ext;
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char *copy;
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copy = kstrdup(path, GFP_KERNEL);
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if (!copy)
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return NULL;
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old_ext = strrchr(copy, '.');
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if (old_ext)
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*old_ext = '\0';
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if (dir)
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target = kasprintf(GFP_KERNEL, "%s/%s.%s", dir, copy, ext);
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else
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target = kasprintf(GFP_KERNEL, "%s.%s", copy, ext);
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kfree(copy);
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return target;
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}
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/*
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* Construct a string representing the symbolic link target for the given
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* gcov data file name and link type. Depending on the link type and the
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* location of the data file, the link target can either point to a
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* subdirectory of srctree, objtree or in an external location.
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*/
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static char *get_link_target(const char *filename, const struct gcov_link *ext)
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{
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const char *rel;
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char *result;
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if (strncmp(filename, objtree, strlen(objtree)) == 0) {
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rel = filename + strlen(objtree) + 1;
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if (ext->dir == SRC_TREE)
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result = link_target(srctree, rel, ext->ext);
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else
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result = link_target(objtree, rel, ext->ext);
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} else {
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/* External compilation. */
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result = link_target(NULL, filename, ext->ext);
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}
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return result;
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}
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#define SKEW_PREFIX ".tmp_"
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/*
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* For a filename .tmp_filename.ext return filename.ext. Needed to compensate
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* for filename skewing caused by the mod-versioning mechanism.
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*/
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static const char *deskew(const char *basename)
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{
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if (strncmp(basename, SKEW_PREFIX, sizeof(SKEW_PREFIX) - 1) == 0)
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return basename + sizeof(SKEW_PREFIX) - 1;
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return basename;
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}
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/*
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* Create links to additional files (usually .c and .gcno files) which the
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* gcov tool expects to find in the same directory as the gcov data file.
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*/
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static void add_links(struct gcov_node *node, struct dentry *parent)
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{
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char *basename;
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char *target;
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int num;
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int i;
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for (num = 0; gcov_link[num].ext; num++)
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/* Nothing. */;
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node->links = kcalloc(num, sizeof(struct dentry *), GFP_KERNEL);
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if (!node->links)
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return;
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for (i = 0; i < num; i++) {
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target = get_link_target(get_node_info(node)->filename,
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&gcov_link[i]);
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if (!target)
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goto out_err;
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basename = strrchr(target, '/');
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if (!basename)
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goto out_err;
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basename++;
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node->links[i] = debugfs_create_symlink(deskew(basename),
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parent, target);
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if (!node->links[i])
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goto out_err;
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kfree(target);
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}
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return;
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out_err:
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kfree(target);
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while (i-- > 0)
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debugfs_remove(node->links[i]);
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kfree(node->links);
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node->links = NULL;
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}
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static const struct file_operations gcov_data_fops = {
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.open = gcov_seq_open,
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.release = gcov_seq_release,
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.read = seq_read,
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.llseek = seq_lseek,
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.write = gcov_seq_write,
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};
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/* Basic initialization of a new node. */
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static void init_node(struct gcov_node *node, struct gcov_info *info,
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const char *name, struct gcov_node *parent)
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{
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INIT_LIST_HEAD(&node->list);
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INIT_LIST_HEAD(&node->children);
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INIT_LIST_HEAD(&node->all);
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node->info = info;
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node->parent = parent;
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if (name)
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strcpy(node->name, name);
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}
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/*
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* Create a new node and associated debugfs entry. Needs to be called with
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* node_lock held.
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*/
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static struct gcov_node *new_node(struct gcov_node *parent,
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struct gcov_info *info, const char *name)
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{
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struct gcov_node *node;
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node = kzalloc(sizeof(struct gcov_node) + strlen(name) + 1, GFP_KERNEL);
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if (!node) {
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pr_warning("out of memory\n");
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return NULL;
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}
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init_node(node, info, name, parent);
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/* Differentiate between gcov data file nodes and directory nodes. */
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if (info) {
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node->dentry = debugfs_create_file(deskew(node->name), 0600,
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parent->dentry, node, &gcov_data_fops);
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} else
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node->dentry = debugfs_create_dir(node->name, parent->dentry);
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if (!node->dentry) {
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pr_warning("could not create file\n");
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kfree(node);
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return NULL;
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}
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if (info)
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add_links(node, parent->dentry);
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list_add(&node->list, &parent->children);
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list_add(&node->all, &all_head);
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return node;
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}
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/* Remove symbolic links associated with node. */
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static void remove_links(struct gcov_node *node)
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{
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int i;
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if (!node->links)
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return;
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for (i = 0; gcov_link[i].ext; i++)
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debugfs_remove(node->links[i]);
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kfree(node->links);
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node->links = NULL;
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}
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/*
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* Remove node from all lists and debugfs and release associated resources.
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* Needs to be called with node_lock held.
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*/
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static void release_node(struct gcov_node *node)
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{
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list_del(&node->list);
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list_del(&node->all);
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debugfs_remove(node->dentry);
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remove_links(node);
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if (node->ghost)
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gcov_info_free(node->ghost);
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kfree(node);
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}
|
||
|
|
||
|
/* 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_for_each_entry(node, &parent->children, list) {
|
||
|
if (strcmp(node->name, name) == 0)
|
||
|
return node;
|
||
|
}
|
||
|
|
||
|
return NULL;
|
||
|
}
|
||
|
|
||
|
/*
|
||
|
* write() implementation for reset file. Reset all profiling data to zero
|
||
|
* and remove ghost nodes.
|
||
|
*/
|
||
|
static ssize_t reset_write(struct file *file, const char __user *addr,
|
||
|
size_t len, loff_t *pos)
|
||
|
{
|
||
|
struct gcov_node *node;
|
||
|
|
||
|
mutex_lock(&node_lock);
|
||
|
restart:
|
||
|
list_for_each_entry(node, &all_head, all) {
|
||
|
if (node->info)
|
||
|
gcov_info_reset(node->info);
|
||
|
else if (list_empty(&node->children)) {
|
||
|
remove_node(node);
|
||
|
/* Several nodes may have gone - restart loop. */
|
||
|
goto restart;
|
||
|
}
|
||
|
}
|
||
|
mutex_unlock(&node_lock);
|
||
|
|
||
|
return len;
|
||
|
}
|
||
|
|
||
|
/* read() implementation for reset file. Unused. */
|
||
|
static ssize_t reset_read(struct file *file, char __user *addr, size_t len,
|
||
|
loff_t *pos)
|
||
|
{
|
||
|
/* Allow read operation so that a recursive copy won't fail. */
|
||
|
return 0;
|
||
|
}
|
||
|
|
||
|
static const struct file_operations gcov_reset_fops = {
|
||
|
.write = reset_write,
|
||
|
.read = reset_read,
|
||
|
};
|
||
|
|
||
|
/*
|
||
|
* 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 = kstrdup(info->filename, GFP_KERNEL);
|
||
|
if (!filename)
|
||
|
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:
|
||
|
kfree(filename);
|
||
|
return;
|
||
|
|
||
|
err_remove:
|
||
|
remove_node(parent);
|
||
|
goto out;
|
||
|
}
|
||
|
|
||
|
/*
|
||
|
* The profiling data set associated with this node is being unloaded. Store a
|
||
|
* copy of the profiling data and turn this node into a "ghost".
|
||
|
*/
|
||
|
static int ghost_node(struct gcov_node *node)
|
||
|
{
|
||
|
node->ghost = gcov_info_dup(node->info);
|
||
|
if (!node->ghost) {
|
||
|
pr_warning("could not save data for '%s' (out of memory)\n",
|
||
|
node->info->filename);
|
||
|
return -ENOMEM;
|
||
|
}
|
||
|
node->info = NULL;
|
||
|
|
||
|
return 0;
|
||
|
}
|
||
|
|
||
|
/*
|
||
|
* Profiling data for this node has been loaded again. Add profiling data
|
||
|
* from previous instantiation and turn this node into a regular node.
|
||
|
*/
|
||
|
static void revive_node(struct gcov_node *node, struct gcov_info *info)
|
||
|
{
|
||
|
if (gcov_info_is_compatible(node->ghost, info))
|
||
|
gcov_info_add(info, node->ghost);
|
||
|
else {
|
||
|
pr_warning("discarding saved data for '%s' (version changed)\n",
|
||
|
info->filename);
|
||
|
}
|
||
|
gcov_info_free(node->ghost);
|
||
|
node->ghost = NULL;
|
||
|
node->info = info;
|
||
|
}
|
||
|
|
||
|
/*
|
||
|
* Callback to create/remove profiling files when code compiled with
|
||
|
* -fprofile-arcs is loaded/unloaded.
|
||
|
*/
|
||
|
void gcov_event(enum gcov_action action, struct gcov_info *info)
|
||
|
{
|
||
|
struct gcov_node *node;
|
||
|
|
||
|
mutex_lock(&node_lock);
|
||
|
node = get_node_by_name(info->filename);
|
||
|
switch (action) {
|
||
|
case GCOV_ADD:
|
||
|
/* Add new node or revive ghost. */
|
||
|
if (!node) {
|
||
|
add_node(info);
|
||
|
break;
|
||
|
}
|
||
|
if (gcov_persist)
|
||
|
revive_node(node, info);
|
||
|
else {
|
||
|
pr_warning("could not add '%s' (already exists)\n",
|
||
|
info->filename);
|
||
|
}
|
||
|
break;
|
||
|
case GCOV_REMOVE:
|
||
|
/* Remove node or turn into ghost. */
|
||
|
if (!node) {
|
||
|
pr_warning("could not remove '%s' (not found)\n",
|
||
|
info->filename);
|
||
|
break;
|
||
|
}
|
||
|
if (gcov_persist) {
|
||
|
if (!ghost_node(node))
|
||
|
break;
|
||
|
}
|
||
|
remove_node(node);
|
||
|
break;
|
||
|
}
|
||
|
mutex_unlock(&node_lock);
|
||
|
}
|
||
|
|
||
|
/* Create debugfs entries. */
|
||
|
static __init int gcov_fs_init(void)
|
||
|
{
|
||
|
int rc = -EIO;
|
||
|
|
||
|
init_node(&root_node, NULL, NULL, NULL);
|
||
|
/*
|
||
|
* /sys/kernel/debug/gcov will be parent for the reset control file
|
||
|
* and all profiling files.
|
||
|
*/
|
||
|
root_node.dentry = debugfs_create_dir("gcov", NULL);
|
||
|
if (!root_node.dentry)
|
||
|
goto err_remove;
|
||
|
/*
|
||
|
* Create reset file which resets all profiling counts when written
|
||
|
* to.
|
||
|
*/
|
||
|
reset_dentry = debugfs_create_file("reset", 0600, root_node.dentry,
|
||
|
NULL, &gcov_reset_fops);
|
||
|
if (!reset_dentry)
|
||
|
goto err_remove;
|
||
|
/* Replay previous events to get our fs hierarchy up-to-date. */
|
||
|
gcov_enable_events();
|
||
|
return 0;
|
||
|
|
||
|
err_remove:
|
||
|
pr_err("init failed\n");
|
||
|
if (root_node.dentry)
|
||
|
debugfs_remove(root_node.dentry);
|
||
|
|
||
|
return rc;
|
||
|
}
|
||
|
device_initcall(gcov_fs_init);
|