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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#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 <linux/mm.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);
#define ITER_STRIDE PAGE_SIZE
/** * struct gcov_iterator - specifies current file position in logical records * @info: associated profiling data * @buffer: buffer containing file data * @size: size of buffer * @pos: current position in file */struct gcov_iterator { struct gcov_info *info; size_t size; loff_t pos; char buffer[] __counted_by(size);};
/** * gcov_iter_new - allocate and initialize profiling data iterator * @info: profiling data set to be iterated * * Return file iterator on success, %NULL otherwise. */static struct gcov_iterator *gcov_iter_new(struct gcov_info *info){ struct gcov_iterator *iter; size_t size;
/* Dry-run to get the actual buffer size. */ size = convert_to_gcda(NULL, info);
iter = kvmalloc_flex(*iter, buffer, size); if (!iter) return NULL;
iter->info = info; iter->size = size; convert_to_gcda(iter->buffer, info);
return iter;}
/** * gcov_iter_free - free iterator data * @iter: file iterator */static void gcov_iter_free(struct gcov_iterator *iter){ kvfree(iter);}
/** * gcov_iter_get_info - return profiling data set for given file iterator * @iter: file iterator */static struct gcov_info *gcov_iter_get_info(struct gcov_iterator *iter){ return iter->info;}
/** * gcov_iter_start - reset file iterator to starting position * @iter: file iterator */static void gcov_iter_start(struct gcov_iterator *iter){ iter->pos = 0;}
/** * gcov_iter_next - advance file iterator to next logical record * @iter: file iterator * * Return zero if new position is valid, non-zero if iterator has reached end. */static int gcov_iter_next(struct gcov_iterator *iter){ if (iter->pos < iter->size) iter->pos += ITER_STRIDE;
if (iter->pos >= iter->size) return -EINVAL;
return 0;}
/** * gcov_iter_write - write data for current pos to seq_file * @iter: file iterator * @seq: seq_file handle * * Return zero on success, non-zero otherwise. */static int gcov_iter_write(struct gcov_iterator *iter, struct seq_file *seq){ size_t len;
if (iter->pos >= iter->size) return -EINVAL;
len = ITER_STRIDE; if (iter->pos + len > iter->size) len = iter->size - iter->pos;
seq_write(seq, iter->buffer + iter->pos, len);
return 0;}
/* * 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 = kzalloc_objs(struct dentry *, num); 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 = kzalloc_objs(struct gcov_info *, 1); 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 = kzalloc_objs(struct gcov_info *, num + 1); 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);