--- /dev/null
+/*
+ * 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
+ */
+
+#define pr_fmt(fmt) "gcov: " fmt
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/debugfs.h>
+#include <linux/fs.h>
+#include <linux/list.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/mutex.h>
+#include <linux/seq_file.h>
+#include "gcov.h"
+
+/**
+ * struct gcov_node - represents a debugfs entry
+ * @list: list head for child node list
+ * @children: child nodes
+ * @all: list head 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 {
+ struct list_head list;
+ struct list_head children;
+ struct list_head all;
+ 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];
+};
+
+static const char objtree[] = OBJTREE;
+static const char srctree[] = SRCTREE;
+static struct gcov_node root_node;
+static struct dentry *reset_dentry;
+static LIST_HEAD(all_head);
+static DEFINE_MUTEX(node_lock);
+
+/* If non-zero, keep copies of profiling data for unloaded modules. */
+static int gcov_persist = 1;
+
+static int __init gcov_persist_setup(char *str)
+{
+ unsigned long val;
+
+ if (kstrtoul(str, 0, &val)) {
+ pr_warn("invalid gcov_persist parameter '%s'\n", str);
+ return 0;
+ }
+ gcov_persist = val;
+ pr_info("setting gcov_persist to %d\n", gcov_persist);
+
+ return 1;
+}
+__setup("gcov_persist=", gcov_persist_setup);
+
+/*
+ * 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, loff_t *pos)
+{
+ loff_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, loff_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))
+ 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)
+ 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;
+
+ mutex_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)
+ goto out_unlock;
+ iter = gcov_iter_new(info);
+ if (!iter)
+ 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:
+ mutex_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_for_each_entry(node, &all_head, all) {
+ 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]);
+}
+
+static void remove_node(struct gcov_node *node);
+
+/*
+ * 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 __user *addr,
+ size_t len, loff_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);
+ mutex_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);
+ mutex_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 = kstrdup(path, GFP_KERNEL);
+ if (!copy)
+ return NULL;
+ old_ext = strrchr(copy, '.');
+ if (old_ext)
+ *old_ext = '\0';
+ if (dir)
+ target = kasprintf(GFP_KERNEL, "%s/%s.%s", dir, copy, ext);
+ else
+ target = kasprintf(GFP_KERNEL, "%s.%s", copy, ext);
+ kfree(copy);
+
+ 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 *basename;
+ char *target;
+ int num;
+ int i;
+
+ for (num = 0; gcov_link[num].ext; num++)
+ /* Nothing. */;
+ node->links = kcalloc(num, sizeof(struct dentry *), GFP_KERNEL);
+ if (!node->links)
+ return;
+ for (i = 0; i < num; i++) {
+ target = get_link_target(
+ gcov_info_filename(get_node_info(node)),
+ &gcov_link[i]);
+ if (!target)
+ goto out_err;
+ basename = kbasename(target);
+ if (basename == target)
+ goto out_err;
+ node->links[i] = debugfs_create_symlink(deskew(basename),
+ parent, target);
+ if (!node->links[i])
+ goto out_err;
+ kfree(target);
+ }
+
+ return;
+out_err:
+ kfree(target);
+ while (i-- > 0)
+ debugfs_remove(node->links[i]);
+ kfree(node->links);
+ 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)
+{
+ INIT_LIST_HEAD(&node->list);
+ INIT_LIST_HEAD(&node->children);
+ INIT_LIST_HEAD(&node->all);
+ 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 = kzalloc(sizeof(struct gcov_node) + strlen(name) + 1, GFP_KERNEL);
+ if (!node)
+ goto err_nomem;
+ if (info) {
+ node->loaded_info = kcalloc(1, sizeof(struct gcov_info *),
+ GFP_KERNEL);
+ 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) {
+ pr_warn("could not create file\n");
+ kfree(node);
+ return NULL;
+ }
+ if (info)
+ add_links(node, parent->dentry);
+ list_add(&node->list, &parent->children);
+ list_add(&node->all, &all_head);
+
+ return node;
+
+err_nomem:
+ kfree(node);
+ pr_warn("out of memory\n");
+ return NULL;
+}
+
+/* Remove symbolic links associated with node. */
+static void remove_links(struct gcov_node *node)
+{
+ int i;
+
+ if (!node->links)
+ return;
+ for (i = 0; gcov_link[i].ext; i++)
+ debugfs_remove(node->links[i]);
+ kfree(node->links);
+ 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_del(&node->list);
+ list_del(&node->all);
+ debugfs_remove(node->dentry);
+ remove_links(node);
+ kfree(node->loaded_info);
+ if (node->unloaded_info)
+ gcov_info_free(node->unloaded_info);
+ kfree(node);
+}
+
+/* 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 nodes for which all associated object files are unloaded.
+ */
+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->num_loaded > 0)
+ reset_node(node);
+ 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,
+ .llseek = noop_llseek,
+};
+
+/*
+ * 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(gcov_info_filename(info), 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;
+}
+
+/*
+ * 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 = kcalloc(num + 1, sizeof(struct gcov_info *), GFP_KERNEL);
+ if (!loaded_info) {
+ pr_warn("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)) {
+ pr_warn("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)) {
+ pr_warn("could not add '%s' (incompatible "
+ "version)\n", gcov_info_filename(info));
+ kfree(loaded_info);
+ return;
+ }
+ }
+ /* Overwrite previous array. */
+ kfree(node->loaded_info);
+ 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) {
+ pr_warn("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) {
+ pr_warn("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. */
+ kfree(node->loaded_info);
+ 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.
+ */
+void gcov_event(enum gcov_action action, struct gcov_info *info)
+{
+ struct gcov_node *node;
+
+ mutex_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 {
+ pr_warn("could not remove '%s' (not found)\n",
+ gcov_info_filename(info));
+ }
+ 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");
+ debugfs_remove(root_node.dentry);
+
+ return rc;
+}
+device_initcall(gcov_fs_init);
Code Review / kvmfornfv.git / blobdiff