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OpenCloudOS-Kernel/kernel/trace/trace_events_user.c

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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (c) 2021, Microsoft Corporation.
*
* Authors:
* Beau Belgrave <beaub@linux.microsoft.com>
*/
#include <linux/bitmap.h>
#include <linux/cdev.h>
#include <linux/hashtable.h>
#include <linux/list.h>
#include <linux/io.h>
#include <linux/uio.h>
#include <linux/ioctl.h>
#include <linux/jhash.h>
#include <linux/trace_events.h>
#include <linux/tracefs.h>
#include <linux/types.h>
#include <linux/uaccess.h>
/* Reminder to move to uapi when everything works */
#ifdef CONFIG_COMPILE_TEST
#include <linux/user_events.h>
#else
#include <uapi/linux/user_events.h>
#endif
#include "trace.h"
#include "trace_dynevent.h"
#define USER_EVENTS_PREFIX_LEN (sizeof(USER_EVENTS_PREFIX)-1)
#define FIELD_DEPTH_TYPE 0
#define FIELD_DEPTH_NAME 1
#define FIELD_DEPTH_SIZE 2
/*
* Limits how many trace_event calls user processes can create:
* Must be a power of two of PAGE_SIZE.
*/
#define MAX_PAGE_ORDER 0
#define MAX_PAGES (1 << MAX_PAGE_ORDER)
#define MAX_EVENTS (MAX_PAGES * PAGE_SIZE)
/* Limit how long of an event name plus args within the subsystem. */
#define MAX_EVENT_DESC 512
#define EVENT_NAME(user_event) ((user_event)->tracepoint.name)
#define MAX_FIELD_ARRAY_SIZE 1024
#define MAX_FIELD_ARG_NAME 256
static char *register_page_data;
static DEFINE_MUTEX(reg_mutex);
static DEFINE_HASHTABLE(register_table, 4);
static DECLARE_BITMAP(page_bitmap, MAX_EVENTS);
/*
* Stores per-event properties, as users register events
* within a file a user_event might be created if it does not
* already exist. These are globally used and their lifetime
* is tied to the refcnt member. These cannot go away until the
* refcnt reaches zero.
*/
struct user_event {
struct tracepoint tracepoint;
struct trace_event_call call;
struct trace_event_class class;
struct dyn_event devent;
struct hlist_node node;
struct list_head fields;
struct list_head validators;
atomic_t refcnt;
int index;
int flags;
int min_size;
};
/*
* Stores per-file events references, as users register events
* within a file this structure is modified and freed via RCU.
* The lifetime of this struct is tied to the lifetime of the file.
* These are not shared and only accessible by the file that created it.
*/
struct user_event_refs {
struct rcu_head rcu;
int count;
struct user_event *events[];
};
#define VALIDATOR_ENSURE_NULL (1 << 0)
#define VALIDATOR_REL (1 << 1)
struct user_event_validator {
struct list_head link;
int offset;
int flags;
};
typedef void (*user_event_func_t) (struct user_event *user, struct iov_iter *i,
void *tpdata, bool *faulted);
static int user_event_parse(char *name, char *args, char *flags,
struct user_event **newuser);
static u32 user_event_key(char *name)
{
return jhash(name, strlen(name), 0);
}
static __always_inline __must_check
size_t copy_nofault(void *addr, size_t bytes, struct iov_iter *i)
{
size_t ret;
pagefault_disable();
ret = copy_from_iter_nocache(addr, bytes, i);
pagefault_enable();
return ret;
}
static struct list_head *user_event_get_fields(struct trace_event_call *call)
{
struct user_event *user = (struct user_event *)call->data;
return &user->fields;
}
/*
* Parses a register command for user_events
* Format: event_name[:FLAG1[,FLAG2...]] [field1[;field2...]]
*
* Example event named 'test' with a 20 char 'msg' field with an unsigned int
* 'id' field after:
* test char[20] msg;unsigned int id
*
* NOTE: Offsets are from the user data perspective, they are not from the
* trace_entry/buffer perspective. We automatically add the common properties
* sizes to the offset for the user.
*
* Upon success user_event has its ref count increased by 1.
*/
static int user_event_parse_cmd(char *raw_command, struct user_event **newuser)
{
char *name = raw_command;
char *args = strpbrk(name, " ");
char *flags;
if (args)
*args++ = '\0';
flags = strpbrk(name, ":");
if (flags)
*flags++ = '\0';
return user_event_parse(name, args, flags, newuser);
}
static int user_field_array_size(const char *type)
{
const char *start = strchr(type, '[');
char val[8];
char *bracket;
int size = 0;
if (start == NULL)
return -EINVAL;
if (strscpy(val, start + 1, sizeof(val)) <= 0)
return -EINVAL;
bracket = strchr(val, ']');
if (!bracket)
return -EINVAL;
*bracket = '\0';
if (kstrtouint(val, 0, &size))
return -EINVAL;
if (size > MAX_FIELD_ARRAY_SIZE)
return -EINVAL;
return size;
}
static int user_field_size(const char *type)
{
/* long is not allowed from a user, since it's ambigious in size */
if (strcmp(type, "s64") == 0)
return sizeof(s64);
if (strcmp(type, "u64") == 0)
return sizeof(u64);
if (strcmp(type, "s32") == 0)
return sizeof(s32);
if (strcmp(type, "u32") == 0)
return sizeof(u32);
if (strcmp(type, "int") == 0)
return sizeof(int);
if (strcmp(type, "unsigned int") == 0)
return sizeof(unsigned int);
if (strcmp(type, "s16") == 0)
return sizeof(s16);
if (strcmp(type, "u16") == 0)
return sizeof(u16);
if (strcmp(type, "short") == 0)
return sizeof(short);
if (strcmp(type, "unsigned short") == 0)
return sizeof(unsigned short);
if (strcmp(type, "s8") == 0)
return sizeof(s8);
if (strcmp(type, "u8") == 0)
return sizeof(u8);
if (strcmp(type, "char") == 0)
return sizeof(char);
if (strcmp(type, "unsigned char") == 0)
return sizeof(unsigned char);
if (str_has_prefix(type, "char["))
return user_field_array_size(type);
if (str_has_prefix(type, "unsigned char["))
return user_field_array_size(type);
if (str_has_prefix(type, "__data_loc "))
return sizeof(u32);
if (str_has_prefix(type, "__rel_loc "))
return sizeof(u32);
/* Uknown basic type, error */
return -EINVAL;
}
static void user_event_destroy_validators(struct user_event *user)
{
struct user_event_validator *validator, *next;
struct list_head *head = &user->validators;
list_for_each_entry_safe(validator, next, head, link) {
list_del(&validator->link);
kfree(validator);
}
}
static void user_event_destroy_fields(struct user_event *user)
{
struct ftrace_event_field *field, *next;
struct list_head *head = &user->fields;
list_for_each_entry_safe(field, next, head, link) {
list_del(&field->link);
kfree(field);
}
}
static int user_event_add_field(struct user_event *user, const char *type,
const char *name, int offset, int size,
int is_signed, int filter_type)
{
struct user_event_validator *validator;
struct ftrace_event_field *field;
int validator_flags = 0;
field = kmalloc(sizeof(*field), GFP_KERNEL);
if (!field)
return -ENOMEM;
if (str_has_prefix(type, "__data_loc "))
goto add_validator;
if (str_has_prefix(type, "__rel_loc ")) {
validator_flags |= VALIDATOR_REL;
goto add_validator;
}
goto add_field;
add_validator:
if (strstr(type, "char") != 0)
validator_flags |= VALIDATOR_ENSURE_NULL;
validator = kmalloc(sizeof(*validator), GFP_KERNEL);
if (!validator) {
kfree(field);
return -ENOMEM;
}
validator->flags = validator_flags;
validator->offset = offset;
/* Want sequential access when validating */
list_add_tail(&validator->link, &user->validators);
add_field:
field->type = type;
field->name = name;
field->offset = offset;
field->size = size;
field->is_signed = is_signed;
field->filter_type = filter_type;
list_add(&field->link, &user->fields);
/*
* Min size from user writes that are required, this does not include
* the size of trace_entry (common fields).
*/
user->min_size = (offset + size) - sizeof(struct trace_entry);
return 0;
}
/*
* Parses the values of a field within the description
* Format: type name [size]
*/
static int user_event_parse_field(char *field, struct user_event *user,
u32 *offset)
{
char *part, *type, *name;
u32 depth = 0, saved_offset = *offset;
int len, size = -EINVAL;
bool is_struct = false;
field = skip_spaces(field);
if (*field == '\0')
return 0;
/* Handle types that have a space within */
len = str_has_prefix(field, "unsigned ");
if (len)
goto skip_next;
len = str_has_prefix(field, "struct ");
if (len) {
is_struct = true;
goto skip_next;
}
len = str_has_prefix(field, "__data_loc unsigned ");
if (len)
goto skip_next;
len = str_has_prefix(field, "__data_loc ");
if (len)
goto skip_next;
len = str_has_prefix(field, "__rel_loc unsigned ");
if (len)
goto skip_next;
len = str_has_prefix(field, "__rel_loc ");
if (len)
goto skip_next;
goto parse;
skip_next:
type = field;
field = strpbrk(field + len, " ");
if (field == NULL)
return -EINVAL;
*field++ = '\0';
depth++;
parse:
name = NULL;
while ((part = strsep(&field, " ")) != NULL) {
switch (depth++) {
case FIELD_DEPTH_TYPE:
type = part;
break;
case FIELD_DEPTH_NAME:
name = part;
break;
case FIELD_DEPTH_SIZE:
if (!is_struct)
return -EINVAL;
if (kstrtou32(part, 10, &size))
return -EINVAL;
break;
default:
return -EINVAL;
}
}
if (depth < FIELD_DEPTH_SIZE || !name)
return -EINVAL;
if (depth == FIELD_DEPTH_SIZE)
size = user_field_size(type);
if (size == 0)
return -EINVAL;
if (size < 0)
return size;
*offset = saved_offset + size;
return user_event_add_field(user, type, name, saved_offset, size,
type[0] != 'u', FILTER_OTHER);
}
static int user_event_parse_fields(struct user_event *user, char *args)
{
char *field;
u32 offset = sizeof(struct trace_entry);
int ret = -EINVAL;
if (args == NULL)
return 0;
while ((field = strsep(&args, ";")) != NULL) {
ret = user_event_parse_field(field, user, &offset);
if (ret)
break;
}
return ret;
}
static struct trace_event_fields user_event_fields_array[1];
static const char *user_field_format(const char *type)
{
if (strcmp(type, "s64") == 0)
return "%lld";
if (strcmp(type, "u64") == 0)
return "%llu";
if (strcmp(type, "s32") == 0)
return "%d";
if (strcmp(type, "u32") == 0)
return "%u";
if (strcmp(type, "int") == 0)
return "%d";
if (strcmp(type, "unsigned int") == 0)
return "%u";
if (strcmp(type, "s16") == 0)
return "%d";
if (strcmp(type, "u16") == 0)
return "%u";
if (strcmp(type, "short") == 0)
return "%d";
if (strcmp(type, "unsigned short") == 0)
return "%u";
if (strcmp(type, "s8") == 0)
return "%d";
if (strcmp(type, "u8") == 0)
return "%u";
if (strcmp(type, "char") == 0)
return "%d";
if (strcmp(type, "unsigned char") == 0)
return "%u";
if (strstr(type, "char[") != 0)
return "%s";
/* Unknown, likely struct, allowed treat as 64-bit */
return "%llu";
}
static bool user_field_is_dyn_string(const char *type, const char **str_func)
{
if (str_has_prefix(type, "__data_loc ")) {
*str_func = "__get_str";
goto check;
}
if (str_has_prefix(type, "__rel_loc ")) {
*str_func = "__get_rel_str";
goto check;
}
return false;
check:
return strstr(type, "char") != 0;
}
#define LEN_OR_ZERO (len ? len - pos : 0)
static int user_event_set_print_fmt(struct user_event *user, char *buf, int len)
{
struct ftrace_event_field *field, *next;
struct list_head *head = &user->fields;
int pos = 0, depth = 0;
const char *str_func;
pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
list_for_each_entry_safe_reverse(field, next, head, link) {
if (depth != 0)
pos += snprintf(buf + pos, LEN_OR_ZERO, " ");
pos += snprintf(buf + pos, LEN_OR_ZERO, "%s=%s",
field->name, user_field_format(field->type));
depth++;
}
pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
list_for_each_entry_safe_reverse(field, next, head, link) {
if (user_field_is_dyn_string(field->type, &str_func))
pos += snprintf(buf + pos, LEN_OR_ZERO,
", %s(%s)", str_func, field->name);
else
pos += snprintf(buf + pos, LEN_OR_ZERO,
", REC->%s", field->name);
}
return pos + 1;
}
#undef LEN_OR_ZERO
static int user_event_create_print_fmt(struct user_event *user)
{
char *print_fmt;
int len;
len = user_event_set_print_fmt(user, NULL, 0);
print_fmt = kmalloc(len, GFP_KERNEL);
if (!print_fmt)
return -ENOMEM;
user_event_set_print_fmt(user, print_fmt, len);
user->call.print_fmt = print_fmt;
return 0;
}
static enum print_line_t user_event_print_trace(struct trace_iterator *iter,
int flags,
struct trace_event *event)
{
/* Unsafe to try to decode user provided print_fmt, use hex */
trace_print_hex_dump_seq(&iter->seq, "", DUMP_PREFIX_OFFSET, 16,
1, iter->ent, iter->ent_size, true);
return trace_handle_return(&iter->seq);
}
static struct trace_event_functions user_event_funcs = {
.trace = user_event_print_trace,
};
static int user_event_set_call_visible(struct user_event *user, bool visible)
{
int ret;
const struct cred *old_cred;
struct cred *cred;
cred = prepare_creds();
if (!cred)
return -ENOMEM;
/*
* While by default tracefs is locked down, systems can be configured
* to allow user_event files to be less locked down. The extreme case
* being "other" has read/write access to user_events_data/status.
*
* When not locked down, processes may not have permissions to
* add/remove calls themselves to tracefs. We need to temporarily
* switch to root file permission to allow for this scenario.
*/
cred->fsuid = GLOBAL_ROOT_UID;
old_cred = override_creds(cred);
if (visible)
ret = trace_add_event_call(&user->call);
else
ret = trace_remove_event_call(&user->call);
revert_creds(old_cred);
put_cred(cred);
return ret;
}
static int destroy_user_event(struct user_event *user)
{
int ret = 0;
/* Must destroy fields before call removal */
user_event_destroy_fields(user);
ret = user_event_set_call_visible(user, false);
if (ret)
return ret;
dyn_event_remove(&user->devent);
register_page_data[user->index] = 0;
clear_bit(user->index, page_bitmap);
hash_del(&user->node);
user_event_destroy_validators(user);
kfree(user->call.print_fmt);
kfree(EVENT_NAME(user));
kfree(user);
return ret;
}
static struct user_event *find_user_event(char *name, u32 *outkey)
{
struct user_event *user;
u32 key = user_event_key(name);
*outkey = key;
hash_for_each_possible(register_table, user, node, key)
if (!strcmp(EVENT_NAME(user), name)) {
atomic_inc(&user->refcnt);
return user;
}
return NULL;
}
static int user_event_validate(struct user_event *user, void *data, int len)
{
struct list_head *head = &user->validators;
struct user_event_validator *validator;
void *pos, *end = data + len;
u32 loc, offset, size;
list_for_each_entry(validator, head, link) {
pos = data + validator->offset;
/* Already done min_size check, no bounds check here */
loc = *(u32 *)pos;
offset = loc & 0xffff;
size = loc >> 16;
if (likely(validator->flags & VALIDATOR_REL))
pos += offset + sizeof(loc);
else
pos = data + offset;
pos += size;
if (unlikely(pos > end))
return -EFAULT;
if (likely(validator->flags & VALIDATOR_ENSURE_NULL))
if (unlikely(*(char *)(pos - 1) != '\0'))
return -EFAULT;
}
return 0;
}
/*
* Writes the user supplied payload out to a trace file.
*/
static void user_event_ftrace(struct user_event *user, struct iov_iter *i,
void *tpdata, bool *faulted)
{
struct trace_event_file *file;
struct trace_entry *entry;
struct trace_event_buffer event_buffer;
size_t size = sizeof(*entry) + i->count;
file = (struct trace_event_file *)tpdata;
if (!file ||
!(file->flags & EVENT_FILE_FL_ENABLED) ||
trace_trigger_soft_disabled(file))
return;
/* Allocates and fills trace_entry, + 1 of this is data payload */
entry = trace_event_buffer_reserve(&event_buffer, file, size);
if (unlikely(!entry))
return;
if (unlikely(!copy_nofault(entry + 1, i->count, i)))
goto discard;
if (!list_empty(&user->validators) &&
unlikely(user_event_validate(user, entry, size)))
goto discard;
trace_event_buffer_commit(&event_buffer);
return;
discard:
*faulted = true;
__trace_event_discard_commit(event_buffer.buffer,
event_buffer.event);
}
#ifdef CONFIG_PERF_EVENTS
/*
* Writes the user supplied payload out to perf ring buffer.
*/
static void user_event_perf(struct user_event *user, struct iov_iter *i,
void *tpdata, bool *faulted)
{
struct hlist_head *perf_head;
perf_head = this_cpu_ptr(user->call.perf_events);
if (perf_head && !hlist_empty(perf_head)) {
struct trace_entry *perf_entry;
struct pt_regs *regs;
size_t size = sizeof(*perf_entry) + i->count;
int context;
perf_entry = perf_trace_buf_alloc(ALIGN(size, 8),
&regs, &context);
if (unlikely(!perf_entry))
return;
perf_fetch_caller_regs(regs);
if (unlikely(!copy_nofault(perf_entry + 1, i->count, i)))
goto discard;
if (!list_empty(&user->validators) &&
unlikely(user_event_validate(user, perf_entry, size)))
goto discard;
perf_trace_buf_submit(perf_entry, size, context,
user->call.event.type, 1, regs,
perf_head, NULL);
return;
discard:
*faulted = true;
perf_swevent_put_recursion_context(context);
}
}
#endif
/*
* Update the register page that is shared between user processes.
*/
static void update_reg_page_for(struct user_event *user)
{
struct tracepoint *tp = &user->tracepoint;
char status = 0;
if (atomic_read(&tp->key.enabled) > 0) {
struct tracepoint_func *probe_func_ptr;
user_event_func_t probe_func;
rcu_read_lock_sched();
probe_func_ptr = rcu_dereference_sched(tp->funcs);
if (probe_func_ptr) {
do {
probe_func = probe_func_ptr->func;
if (probe_func == user_event_ftrace)
status |= EVENT_STATUS_FTRACE;
#ifdef CONFIG_PERF_EVENTS
else if (probe_func == user_event_perf)
status |= EVENT_STATUS_PERF;
#endif
else
status |= EVENT_STATUS_OTHER;
} while ((++probe_func_ptr)->func);
}
rcu_read_unlock_sched();
}
register_page_data[user->index] = status;
}
/*
* Register callback for our events from tracing sub-systems.
*/
static int user_event_reg(struct trace_event_call *call,
enum trace_reg type,
void *data)
{
struct user_event *user = (struct user_event *)call->data;
int ret = 0;
if (!user)
return -ENOENT;
switch (type) {
case TRACE_REG_REGISTER:
ret = tracepoint_probe_register(call->tp,
call->class->probe,
data);
if (!ret)
goto inc;
break;
case TRACE_REG_UNREGISTER:
tracepoint_probe_unregister(call->tp,
call->class->probe,
data);
goto dec;
#ifdef CONFIG_PERF_EVENTS
case TRACE_REG_PERF_REGISTER:
ret = tracepoint_probe_register(call->tp,
call->class->perf_probe,
data);
if (!ret)
goto inc;
break;
case TRACE_REG_PERF_UNREGISTER:
tracepoint_probe_unregister(call->tp,
call->class->perf_probe,
data);
goto dec;
case TRACE_REG_PERF_OPEN:
case TRACE_REG_PERF_CLOSE:
case TRACE_REG_PERF_ADD:
case TRACE_REG_PERF_DEL:
break;
#endif
}
return ret;
inc:
atomic_inc(&user->refcnt);
update_reg_page_for(user);
return 0;
dec:
update_reg_page_for(user);
atomic_dec(&user->refcnt);
return 0;
}
static int user_event_create(const char *raw_command)
{
struct user_event *user;
char *name;
int ret;
if (!str_has_prefix(raw_command, USER_EVENTS_PREFIX))
return -ECANCELED;
raw_command += USER_EVENTS_PREFIX_LEN;
raw_command = skip_spaces(raw_command);
name = kstrdup(raw_command, GFP_KERNEL);
if (!name)
return -ENOMEM;
mutex_lock(&reg_mutex);
ret = user_event_parse_cmd(name, &user);
if (!ret)
atomic_dec(&user->refcnt);
mutex_unlock(&reg_mutex);
if (ret)
kfree(name);
return ret;
}
static int user_event_show(struct seq_file *m, struct dyn_event *ev)
{
struct user_event *user = container_of(ev, struct user_event, devent);
struct ftrace_event_field *field, *next;
struct list_head *head;
int depth = 0;
seq_printf(m, "%s%s", USER_EVENTS_PREFIX, EVENT_NAME(user));
head = trace_get_fields(&user->call);
list_for_each_entry_safe_reverse(field, next, head, link) {
if (depth == 0)
seq_puts(m, " ");
else
seq_puts(m, "; ");
seq_printf(m, "%s %s", field->type, field->name);
if (str_has_prefix(field->type, "struct "))
seq_printf(m, " %d", field->size);
depth++;
}
seq_puts(m, "\n");
return 0;
}
static bool user_event_is_busy(struct dyn_event *ev)
{
struct user_event *user = container_of(ev, struct user_event, devent);
return atomic_read(&user->refcnt) != 0;
}
static int user_event_free(struct dyn_event *ev)
{
struct user_event *user = container_of(ev, struct user_event, devent);
if (atomic_read(&user->refcnt) != 0)
return -EBUSY;
return destroy_user_event(user);
}
static bool user_field_match(struct ftrace_event_field *field, int argc,
const char **argv, int *iout)
{
char *field_name, *arg_name;
int len, pos, i = *iout;
bool colon = false, match = false;
if (i >= argc)
return false;
len = MAX_FIELD_ARG_NAME;
field_name = kmalloc(len, GFP_KERNEL);
arg_name = kmalloc(len, GFP_KERNEL);
if (!arg_name || !field_name)
goto out;
pos = 0;
for (; i < argc; ++i) {
if (i != *iout)
pos += snprintf(arg_name + pos, len - pos, " ");
pos += snprintf(arg_name + pos, len - pos, argv[i]);
if (strchr(argv[i], ';')) {
++i;
colon = true;
break;
}
}
pos = 0;
pos += snprintf(field_name + pos, len - pos, field->type);
pos += snprintf(field_name + pos, len - pos, " ");
pos += snprintf(field_name + pos, len - pos, field->name);
if (colon)
pos += snprintf(field_name + pos, len - pos, ";");
*iout = i;
match = strcmp(arg_name, field_name) == 0;
out:
kfree(arg_name);
kfree(field_name);
return match;
}
static bool user_fields_match(struct user_event *user, int argc,
const char **argv)
{
struct ftrace_event_field *field, *next;
struct list_head *head = &user->fields;
int i = 0;
list_for_each_entry_safe_reverse(field, next, head, link)
if (!user_field_match(field, argc, argv, &i))
return false;
if (i != argc)
return false;
return true;
}
static bool user_event_match(const char *system, const char *event,
int argc, const char **argv, struct dyn_event *ev)
{
struct user_event *user = container_of(ev, struct user_event, devent);
bool match;
match = strcmp(EVENT_NAME(user), event) == 0 &&
(!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);
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);
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, &copy, tpdata, &faulted);
} while ((++probe_func_ptr)->func);
}
rcu_read_unlock_sched();
if (unlikely(faulted))
return -EFAULT;
}
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(&reg_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, &reg);
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);
/* 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);
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(&reg_mutex);
ret = user_events_ioctl_reg(file, uarg);
mutex_unlock(&reg_mutex);
break;
case DIAG_IOCSDEL:
mutex_lock(&reg_mutex);
ret = user_events_ioctl_del(file, uarg);
mutex_unlock(&reg_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(&reg_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(&reg_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(&reg_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(&reg_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)
{
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);
pages = alloc_pages(GFP_KERNEL | __GFP_ZERO, MAX_PAGE_ORDER);
if (!pages)
return -ENOMEM;
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);
__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);
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