// SPDX-License-Identifier: GPL-2.0
|
/*
|
* 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[];
|
};
|
|
static const char objtree[] = OBJTREE;
|
static const char srctree[] = SRCTREE;
|
static struct gcov_node root_node;
|
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;
|
|
(*pos)++;
|
if (gcov_iter_next(iter))
|
return NULL;
|
|
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);
|
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 (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)
|
{
|
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);
|
/*
|
* Create reset file which resets all profiling counts when written
|
* to.
|
*/
|
debugfs_create_file("reset", 0600, root_node.dentry, NULL,
|
&gcov_reset_fops);
|
/* Replay previous events to get our fs hierarchy up-to-date. */
|
gcov_enable_events();
|
return 0;
|
}
|
device_initcall(gcov_fs_init);
|
