Newer
Older
(!system || strcmp(system, USER_EVENTS_SYSTEM) == 0);
if (match && argc > 0)
match = user_fields_match(user, argc, argv);
return match;
}
static struct dyn_event_operations user_event_dops = {
.create = user_event_create,
.show = user_event_show,
.is_busy = user_event_is_busy,
.free = user_event_free,
.match = user_event_match,
};
static int user_event_trace_register(struct user_event *user)
{
int ret;
ret = register_trace_event(&user->call.event);
if (!ret)
return -ENODEV;
ret = user_event_set_call_visible(user, true);
if (ret)
unregister_trace_event(&user->call.event);
return ret;
}
/*
* Parses the event name, arguments and flags then registers if successful.
* The name buffer lifetime is owned by this method for success cases only.
* Upon success the returned user_event has its ref count increased by 1.
*/
static int user_event_parse(char *name, char *args, char *flags,
struct user_event **newuser)
{
int ret;
int index;
u32 key;
struct user_event *user;
/* Prevent dyn_event from racing */
mutex_lock(&event_mutex);
user = find_user_event(name, &key);
mutex_unlock(&event_mutex);
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if (user) {
*newuser = user;
/*
* Name is allocated by caller, free it since it already exists.
* Caller only worries about failure cases for freeing.
*/
kfree(name);
return 0;
}
index = find_first_zero_bit(page_bitmap, MAX_EVENTS);
if (index == MAX_EVENTS)
return -EMFILE;
user = kzalloc(sizeof(*user), GFP_KERNEL);
if (!user)
return -ENOMEM;
INIT_LIST_HEAD(&user->class.fields);
INIT_LIST_HEAD(&user->fields);
INIT_LIST_HEAD(&user->validators);
user->tracepoint.name = name;
ret = user_event_parse_fields(user, args);
if (ret)
goto put_user;
ret = user_event_create_print_fmt(user);
if (ret)
goto put_user;
user->call.data = user;
user->call.class = &user->class;
user->call.name = name;
user->call.flags = TRACE_EVENT_FL_TRACEPOINT;
user->call.tp = &user->tracepoint;
user->call.event.funcs = &user_event_funcs;
user->class.system = USER_EVENTS_SYSTEM;
user->class.fields_array = user_event_fields_array;
user->class.get_fields = user_event_get_fields;
user->class.reg = user_event_reg;
user->class.probe = user_event_ftrace;
#ifdef CONFIG_PERF_EVENTS
user->class.perf_probe = user_event_perf;
#endif
mutex_lock(&event_mutex);
ret = user_event_trace_register(user);
if (ret)
goto put_user_lock;
user->index = index;
/* Ensure we track ref */
atomic_inc(&user->refcnt);
dyn_event_init(&user->devent, &user_event_dops);
dyn_event_add(&user->devent, &user->call);
set_bit(user->index, page_bitmap);
hash_add(register_table, &user->node, key);
mutex_unlock(&event_mutex);
*newuser = user;
return 0;
put_user_lock:
mutex_unlock(&event_mutex);
put_user:
user_event_destroy_fields(user);
user_event_destroy_validators(user);
kfree(user);
return ret;
}
/*
* Deletes a previously created event if it is no longer being used.
*/
static int delete_user_event(char *name)
{
u32 key;
int ret;
struct user_event *user = find_user_event(name, &key);
if (!user)
return -ENOENT;
/* Ensure we are the last ref */
if (atomic_read(&user->refcnt) != 1) {
ret = -EBUSY;
goto put_ref;
}
ret = destroy_user_event(user);
if (ret)
goto put_ref;
return ret;
put_ref:
/* No longer have this ref */
atomic_dec(&user->refcnt);
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return ret;
}
/*
* Validates the user payload and writes via iterator.
*/
static ssize_t user_events_write_core(struct file *file, struct iov_iter *i)
{
struct user_event_refs *refs;
struct user_event *user = NULL;
struct tracepoint *tp;
ssize_t ret = i->count;
int idx;
if (unlikely(copy_from_iter(&idx, sizeof(idx), i) != sizeof(idx)))
return -EFAULT;
rcu_read_lock_sched();
refs = rcu_dereference_sched(file->private_data);
/*
* The refs->events array is protected by RCU, and new items may be
* added. But the user retrieved from indexing into the events array
* shall be immutable while the file is opened.
*/
if (likely(refs && idx < refs->count))
user = refs->events[idx];
rcu_read_unlock_sched();
if (unlikely(user == NULL))
return -ENOENT;
if (unlikely(i->count < user->min_size))
return -EINVAL;
tp = &user->tracepoint;
/*
* It's possible key.enabled disables after this check, however
* we don't mind if a few events are included in this condition.
*/
if (likely(atomic_read(&tp->key.enabled) > 0)) {
struct tracepoint_func *probe_func_ptr;
user_event_func_t probe_func;
struct iov_iter copy;
void *tpdata;
bool faulted;
if (unlikely(fault_in_iov_iter_readable(i, i->count)))
return -EFAULT;
faulted = false;
rcu_read_lock_sched();
probe_func_ptr = rcu_dereference_sched(tp->funcs);
if (probe_func_ptr) {
do {
copy = *i;
probe_func = probe_func_ptr->func;
tpdata = probe_func_ptr->data;
probe_func(user, ©, tpdata, &faulted);
} while ((++probe_func_ptr)->func);
}
rcu_read_unlock_sched();
if (unlikely(faulted))
return -EFAULT;
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}
return ret;
}
static ssize_t user_events_write(struct file *file, const char __user *ubuf,
size_t count, loff_t *ppos)
{
struct iovec iov;
struct iov_iter i;
if (unlikely(*ppos != 0))
return -EFAULT;
if (unlikely(import_single_range(READ, (char *)ubuf, count, &iov, &i)))
return -EFAULT;
return user_events_write_core(file, &i);
}
static ssize_t user_events_write_iter(struct kiocb *kp, struct iov_iter *i)
{
return user_events_write_core(kp->ki_filp, i);
}
static int user_events_ref_add(struct file *file, struct user_event *user)
{
struct user_event_refs *refs, *new_refs;
int i, size, count = 0;
refs = rcu_dereference_protected(file->private_data,
lockdep_is_held(®_mutex));
if (refs) {
count = refs->count;
for (i = 0; i < count; ++i)
if (refs->events[i] == user)
return i;
}
size = struct_size(refs, events, count + 1);
new_refs = kzalloc(size, GFP_KERNEL);
if (!new_refs)
return -ENOMEM;
new_refs->count = count + 1;
for (i = 0; i < count; ++i)
new_refs->events[i] = refs->events[i];
new_refs->events[i] = user;
atomic_inc(&user->refcnt);
rcu_assign_pointer(file->private_data, new_refs);
if (refs)
kfree_rcu(refs, rcu);
return i;
}
static long user_reg_get(struct user_reg __user *ureg, struct user_reg *kreg)
{
u32 size;
long ret;
ret = get_user(size, &ureg->size);
if (ret)
return ret;
if (size > PAGE_SIZE)
return -E2BIG;
return copy_struct_from_user(kreg, sizeof(*kreg), ureg, size);
}
/*
* Registers a user_event on behalf of a user process.
*/
static long user_events_ioctl_reg(struct file *file, unsigned long uarg)
{
struct user_reg __user *ureg = (struct user_reg __user *)uarg;
struct user_reg reg;
struct user_event *user;
char *name;
long ret;
ret = user_reg_get(ureg, ®);
if (ret)
return ret;
name = strndup_user((const char __user *)(uintptr_t)reg.name_args,
MAX_EVENT_DESC);
if (IS_ERR(name)) {
ret = PTR_ERR(name);
return ret;
}
ret = user_event_parse_cmd(name, &user);
if (ret) {
kfree(name);
return ret;
}
ret = user_events_ref_add(file, user);
/* No longer need parse ref, ref_add either worked or not */
atomic_dec(&user->refcnt);
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/* Positive number is index and valid */
if (ret < 0)
return ret;
put_user((u32)ret, &ureg->write_index);
put_user(user->index, &ureg->status_index);
return 0;
}
/*
* Deletes a user_event on behalf of a user process.
*/
static long user_events_ioctl_del(struct file *file, unsigned long uarg)
{
void __user *ubuf = (void __user *)uarg;
char *name;
long ret;
name = strndup_user(ubuf, MAX_EVENT_DESC);
if (IS_ERR(name))
return PTR_ERR(name);
/* event_mutex prevents dyn_event from racing */
mutex_lock(&event_mutex);
ret = delete_user_event(name);
mutex_unlock(&event_mutex);
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kfree(name);
return ret;
}
/*
* Handles the ioctl from user mode to register or alter operations.
*/
static long user_events_ioctl(struct file *file, unsigned int cmd,
unsigned long uarg)
{
long ret = -ENOTTY;
switch (cmd) {
case DIAG_IOCSREG:
mutex_lock(®_mutex);
ret = user_events_ioctl_reg(file, uarg);
mutex_unlock(®_mutex);
break;
case DIAG_IOCSDEL:
mutex_lock(®_mutex);
ret = user_events_ioctl_del(file, uarg);
mutex_unlock(®_mutex);
break;
}
return ret;
}
/*
* Handles the final close of the file from user mode.
*/
static int user_events_release(struct inode *node, struct file *file)
{
struct user_event_refs *refs;
struct user_event *user;
int i;
/*
* Ensure refs cannot change under any situation by taking the
* register mutex during the final freeing of the references.
*/
mutex_lock(®_mutex);
refs = file->private_data;
if (!refs)
goto out;
/*
* The lifetime of refs has reached an end, it's tied to this file.
* The underlying user_events are ref counted, and cannot be freed.
* After this decrement, the user_events may be freed elsewhere.
*/
for (i = 0; i < refs->count; ++i) {
user = refs->events[i];
if (user)
atomic_dec(&user->refcnt);
}
out:
file->private_data = NULL;
mutex_unlock(®_mutex);
kfree(refs);
return 0;
}
static const struct file_operations user_data_fops = {
.write = user_events_write,
.write_iter = user_events_write_iter,
.unlocked_ioctl = user_events_ioctl,
.release = user_events_release,
};
/*
* Maps the shared page into the user process for checking if event is enabled.
*/
static int user_status_mmap(struct file *file, struct vm_area_struct *vma)
{
unsigned long size = vma->vm_end - vma->vm_start;
if (size != MAX_EVENTS)
return -EINVAL;
return remap_pfn_range(vma, vma->vm_start,
virt_to_phys(register_page_data) >> PAGE_SHIFT,
size, vm_get_page_prot(VM_READ));
}
static void *user_seq_start(struct seq_file *m, loff_t *pos)
{
if (*pos)
return NULL;
return (void *)1;
}
static void *user_seq_next(struct seq_file *m, void *p, loff_t *pos)
{
++*pos;
return NULL;
}
static void user_seq_stop(struct seq_file *m, void *p)
{
}
static int user_seq_show(struct seq_file *m, void *p)
{
struct user_event *user;
char status;
int i, active = 0, busy = 0, flags;
mutex_lock(®_mutex);
hash_for_each(register_table, i, user, node) {
status = register_page_data[user->index];
flags = user->flags;
seq_printf(m, "%d:%s", user->index, EVENT_NAME(user));
if (flags != 0 || status != 0)
seq_puts(m, " #");
if (status != 0) {
seq_puts(m, " Used by");
if (status & EVENT_STATUS_FTRACE)
seq_puts(m, " ftrace");
if (status & EVENT_STATUS_PERF)
seq_puts(m, " perf");
if (status & EVENT_STATUS_OTHER)
seq_puts(m, " other");
busy++;
}
seq_puts(m, "\n");
active++;
}
mutex_unlock(®_mutex);
seq_puts(m, "\n");
seq_printf(m, "Active: %d\n", active);
seq_printf(m, "Busy: %d\n", busy);
seq_printf(m, "Max: %ld\n", MAX_EVENTS);
return 0;
}
static const struct seq_operations user_seq_ops = {
.start = user_seq_start,
.next = user_seq_next,
.stop = user_seq_stop,
.show = user_seq_show,
};
static int user_status_open(struct inode *node, struct file *file)
{
return seq_open(file, &user_seq_ops);
}
static const struct file_operations user_status_fops = {
.open = user_status_open,
.mmap = user_status_mmap,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};
/*
* Creates a set of tracefs files to allow user mode interactions.
*/
static int create_user_tracefs(void)
{
struct dentry *edata, *emmap;
edata = tracefs_create_file("user_events_data", TRACE_MODE_WRITE,
NULL, NULL, &user_data_fops);
if (!edata) {
pr_warn("Could not create tracefs 'user_events_data' entry\n");
goto err;
}
/* mmap with MAP_SHARED requires writable fd */
emmap = tracefs_create_file("user_events_status", TRACE_MODE_WRITE,
NULL, NULL, &user_status_fops);
if (!emmap) {
tracefs_remove(edata);
pr_warn("Could not create tracefs 'user_events_mmap' entry\n");
goto err;
}
return 0;
err:
return -ENODEV;
}
static void set_page_reservations(bool set)
{
int page;
for (page = 0; page < MAX_PAGES; ++page) {
void *addr = register_page_data + (PAGE_SIZE * page);
if (set)
SetPageReserved(virt_to_page(addr));
else
ClearPageReserved(virt_to_page(addr));
}
}
static int __init trace_events_user_init(void)
{
Steven Rostedt (Google)
committed
struct page *pages;
int ret;
/* Zero all bits beside 0 (which is reserved for failures) */
bitmap_zero(page_bitmap, MAX_EVENTS);
set_bit(0, page_bitmap);
Steven Rostedt (Google)
committed
pages = alloc_pages(GFP_KERNEL | __GFP_ZERO, MAX_PAGE_ORDER);
if (!pages)
return -ENOMEM;
Steven Rostedt (Google)
committed
register_page_data = page_address(pages);
set_page_reservations(true);
ret = create_user_tracefs();
if (ret) {
pr_warn("user_events could not register with tracefs\n");
set_page_reservations(false);
Steven Rostedt (Google)
committed
__free_pages(pages, MAX_PAGE_ORDER);
return ret;
}
if (dyn_event_register(&user_event_dops))
pr_warn("user_events could not register with dyn_events\n");
return 0;
}
fs_initcall(trace_events_user_init);