linux/kernel/trace/trace_kprobe.c
Linus Torvalds 41cbc01f6e The updates included in this pull request for ftrace are:
o Several clean ups to the code
 
    One such clean up was to convert to 64 bit time keeping, in the
    ring buffer benchmark code.
 
  o Adding of __print_array() helper macro for TRACE_EVENT()
 
  o Updating the sample/trace_events/ to add samples of different ways to
    make trace events. Lots of features have been added since the sample
    code was made, and these features are mostly unknown. Developers
    have been making their own hacks to do things that are already available.
 
  o Performance improvements. Most notably, I found a performance bug where
    a waiter that is waiting for a full page from the ring buffer will
    see that a full page is not available, and go to sleep. The sched
    event caused by it going to sleep would cause it to wake up again.
    It would see that there was still not a full page, and go back to sleep
    again, and that would wake it up again, until finally it would see a
    full page. This change has been marked for stable.
 
    Other improvements include removing global locks from fast paths.
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Merge tag 'trace-v3.20' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:
 "The updates included in this pull request for ftrace are:

   o Several clean ups to the code

     One such clean up was to convert to 64 bit time keeping, in the
     ring buffer benchmark code.

   o Adding of __print_array() helper macro for TRACE_EVENT()

   o Updating the sample/trace_events/ to add samples of different ways
     to make trace events.  Lots of features have been added since the
     sample code was made, and these features are mostly unknown.
     Developers have been making their own hacks to do things that are
     already available.

   o Performance improvements.  Most notably, I found a performance bug
     where a waiter that is waiting for a full page from the ring buffer
     will see that a full page is not available, and go to sleep.  The
     sched event caused by it going to sleep would cause it to wake up
     again.  It would see that there was still not a full page, and go
     back to sleep again, and that would wake it up again, until finally
     it would see a full page.  This change has been marked for stable.

  Other improvements include removing global locks from fast paths"

* tag 'trace-v3.20' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  ring-buffer: Do not wake up a splice waiter when page is not full
  tracing: Fix unmapping loop in tracing_mark_write
  tracing: Add samples of DECLARE_EVENT_CLASS() and DEFINE_EVENT()
  tracing: Add TRACE_EVENT_FN example
  tracing: Add TRACE_EVENT_CONDITION sample
  tracing: Update the TRACE_EVENT fields available in the sample code
  tracing: Separate out initializing top level dir from instances
  tracing: Make tracing_init_dentry_tr() static
  trace: Use 64-bit timekeeping
  tracing: Add array printing helper
  tracing: Remove newline from trace_printk warning banner
  tracing: Use IS_ERR() check for return value of tracing_init_dentry()
  tracing: Remove unneeded includes of debugfs.h and fs.h
  tracing: Remove taking of trace_types_lock in pipe files
  tracing: Add ref count to tracer for when they are being read by pipe
2015-02-12 08:37:41 -08:00

1487 lines
36 KiB
C

/*
* Kprobes-based tracing events
*
* Created by Masami Hiramatsu <mhiramat@redhat.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/module.h>
#include <linux/uaccess.h>
#include "trace_probe.h"
#define KPROBE_EVENT_SYSTEM "kprobes"
/**
* Kprobe event core functions
*/
struct trace_kprobe {
struct list_head list;
struct kretprobe rp; /* Use rp.kp for kprobe use */
unsigned long nhit;
const char *symbol; /* symbol name */
struct trace_probe tp;
};
#define SIZEOF_TRACE_KPROBE(n) \
(offsetof(struct trace_kprobe, tp.args) + \
(sizeof(struct probe_arg) * (n)))
static nokprobe_inline bool trace_kprobe_is_return(struct trace_kprobe *tk)
{
return tk->rp.handler != NULL;
}
static nokprobe_inline const char *trace_kprobe_symbol(struct trace_kprobe *tk)
{
return tk->symbol ? tk->symbol : "unknown";
}
static nokprobe_inline unsigned long trace_kprobe_offset(struct trace_kprobe *tk)
{
return tk->rp.kp.offset;
}
static nokprobe_inline bool trace_kprobe_has_gone(struct trace_kprobe *tk)
{
return !!(kprobe_gone(&tk->rp.kp));
}
static nokprobe_inline bool trace_kprobe_within_module(struct trace_kprobe *tk,
struct module *mod)
{
int len = strlen(mod->name);
const char *name = trace_kprobe_symbol(tk);
return strncmp(mod->name, name, len) == 0 && name[len] == ':';
}
static nokprobe_inline bool trace_kprobe_is_on_module(struct trace_kprobe *tk)
{
return !!strchr(trace_kprobe_symbol(tk), ':');
}
static int register_kprobe_event(struct trace_kprobe *tk);
static int unregister_kprobe_event(struct trace_kprobe *tk);
static DEFINE_MUTEX(probe_lock);
static LIST_HEAD(probe_list);
static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs);
static int kretprobe_dispatcher(struct kretprobe_instance *ri,
struct pt_regs *regs);
/* Memory fetching by symbol */
struct symbol_cache {
char *symbol;
long offset;
unsigned long addr;
};
unsigned long update_symbol_cache(struct symbol_cache *sc)
{
sc->addr = (unsigned long)kallsyms_lookup_name(sc->symbol);
if (sc->addr)
sc->addr += sc->offset;
return sc->addr;
}
void free_symbol_cache(struct symbol_cache *sc)
{
kfree(sc->symbol);
kfree(sc);
}
struct symbol_cache *alloc_symbol_cache(const char *sym, long offset)
{
struct symbol_cache *sc;
if (!sym || strlen(sym) == 0)
return NULL;
sc = kzalloc(sizeof(struct symbol_cache), GFP_KERNEL);
if (!sc)
return NULL;
sc->symbol = kstrdup(sym, GFP_KERNEL);
if (!sc->symbol) {
kfree(sc);
return NULL;
}
sc->offset = offset;
update_symbol_cache(sc);
return sc;
}
/*
* Kprobes-specific fetch functions
*/
#define DEFINE_FETCH_stack(type) \
static void FETCH_FUNC_NAME(stack, type)(struct pt_regs *regs, \
void *offset, void *dest) \
{ \
*(type *)dest = (type)regs_get_kernel_stack_nth(regs, \
(unsigned int)((unsigned long)offset)); \
} \
NOKPROBE_SYMBOL(FETCH_FUNC_NAME(stack, type));
DEFINE_BASIC_FETCH_FUNCS(stack)
/* No string on the stack entry */
#define fetch_stack_string NULL
#define fetch_stack_string_size NULL
#define DEFINE_FETCH_memory(type) \
static void FETCH_FUNC_NAME(memory, type)(struct pt_regs *regs, \
void *addr, void *dest) \
{ \
type retval; \
if (probe_kernel_address(addr, retval)) \
*(type *)dest = 0; \
else \
*(type *)dest = retval; \
} \
NOKPROBE_SYMBOL(FETCH_FUNC_NAME(memory, type));
DEFINE_BASIC_FETCH_FUNCS(memory)
/*
* Fetch a null-terminated string. Caller MUST set *(u32 *)dest with max
* length and relative data location.
*/
static void FETCH_FUNC_NAME(memory, string)(struct pt_regs *regs,
void *addr, void *dest)
{
long ret;
int maxlen = get_rloc_len(*(u32 *)dest);
u8 *dst = get_rloc_data(dest);
u8 *src = addr;
mm_segment_t old_fs = get_fs();
if (!maxlen)
return;
/*
* Try to get string again, since the string can be changed while
* probing.
*/
set_fs(KERNEL_DS);
pagefault_disable();
do
ret = __copy_from_user_inatomic(dst++, src++, 1);
while (dst[-1] && ret == 0 && src - (u8 *)addr < maxlen);
dst[-1] = '\0';
pagefault_enable();
set_fs(old_fs);
if (ret < 0) { /* Failed to fetch string */
((u8 *)get_rloc_data(dest))[0] = '\0';
*(u32 *)dest = make_data_rloc(0, get_rloc_offs(*(u32 *)dest));
} else {
*(u32 *)dest = make_data_rloc(src - (u8 *)addr,
get_rloc_offs(*(u32 *)dest));
}
}
NOKPROBE_SYMBOL(FETCH_FUNC_NAME(memory, string));
/* Return the length of string -- including null terminal byte */
static void FETCH_FUNC_NAME(memory, string_size)(struct pt_regs *regs,
void *addr, void *dest)
{
mm_segment_t old_fs;
int ret, len = 0;
u8 c;
old_fs = get_fs();
set_fs(KERNEL_DS);
pagefault_disable();
do {
ret = __copy_from_user_inatomic(&c, (u8 *)addr + len, 1);
len++;
} while (c && ret == 0 && len < MAX_STRING_SIZE);
pagefault_enable();
set_fs(old_fs);
if (ret < 0) /* Failed to check the length */
*(u32 *)dest = 0;
else
*(u32 *)dest = len;
}
NOKPROBE_SYMBOL(FETCH_FUNC_NAME(memory, string_size));
#define DEFINE_FETCH_symbol(type) \
void FETCH_FUNC_NAME(symbol, type)(struct pt_regs *regs, void *data, void *dest)\
{ \
struct symbol_cache *sc = data; \
if (sc->addr) \
fetch_memory_##type(regs, (void *)sc->addr, dest); \
else \
*(type *)dest = 0; \
} \
NOKPROBE_SYMBOL(FETCH_FUNC_NAME(symbol, type));
DEFINE_BASIC_FETCH_FUNCS(symbol)
DEFINE_FETCH_symbol(string)
DEFINE_FETCH_symbol(string_size)
/* kprobes don't support file_offset fetch methods */
#define fetch_file_offset_u8 NULL
#define fetch_file_offset_u16 NULL
#define fetch_file_offset_u32 NULL
#define fetch_file_offset_u64 NULL
#define fetch_file_offset_string NULL
#define fetch_file_offset_string_size NULL
/* Fetch type information table */
const struct fetch_type kprobes_fetch_type_table[] = {
/* Special types */
[FETCH_TYPE_STRING] = __ASSIGN_FETCH_TYPE("string", string, string,
sizeof(u32), 1, "__data_loc char[]"),
[FETCH_TYPE_STRSIZE] = __ASSIGN_FETCH_TYPE("string_size", u32,
string_size, sizeof(u32), 0, "u32"),
/* Basic types */
ASSIGN_FETCH_TYPE(u8, u8, 0),
ASSIGN_FETCH_TYPE(u16, u16, 0),
ASSIGN_FETCH_TYPE(u32, u32, 0),
ASSIGN_FETCH_TYPE(u64, u64, 0),
ASSIGN_FETCH_TYPE(s8, u8, 1),
ASSIGN_FETCH_TYPE(s16, u16, 1),
ASSIGN_FETCH_TYPE(s32, u32, 1),
ASSIGN_FETCH_TYPE(s64, u64, 1),
ASSIGN_FETCH_TYPE_END
};
/*
* Allocate new trace_probe and initialize it (including kprobes).
*/
static struct trace_kprobe *alloc_trace_kprobe(const char *group,
const char *event,
void *addr,
const char *symbol,
unsigned long offs,
int nargs, bool is_return)
{
struct trace_kprobe *tk;
int ret = -ENOMEM;
tk = kzalloc(SIZEOF_TRACE_KPROBE(nargs), GFP_KERNEL);
if (!tk)
return ERR_PTR(ret);
if (symbol) {
tk->symbol = kstrdup(symbol, GFP_KERNEL);
if (!tk->symbol)
goto error;
tk->rp.kp.symbol_name = tk->symbol;
tk->rp.kp.offset = offs;
} else
tk->rp.kp.addr = addr;
if (is_return)
tk->rp.handler = kretprobe_dispatcher;
else
tk->rp.kp.pre_handler = kprobe_dispatcher;
if (!event || !is_good_name(event)) {
ret = -EINVAL;
goto error;
}
tk->tp.call.class = &tk->tp.class;
tk->tp.call.name = kstrdup(event, GFP_KERNEL);
if (!tk->tp.call.name)
goto error;
if (!group || !is_good_name(group)) {
ret = -EINVAL;
goto error;
}
tk->tp.class.system = kstrdup(group, GFP_KERNEL);
if (!tk->tp.class.system)
goto error;
INIT_LIST_HEAD(&tk->list);
INIT_LIST_HEAD(&tk->tp.files);
return tk;
error:
kfree(tk->tp.call.name);
kfree(tk->symbol);
kfree(tk);
return ERR_PTR(ret);
}
static void free_trace_kprobe(struct trace_kprobe *tk)
{
int i;
for (i = 0; i < tk->tp.nr_args; i++)
traceprobe_free_probe_arg(&tk->tp.args[i]);
kfree(tk->tp.call.class->system);
kfree(tk->tp.call.name);
kfree(tk->symbol);
kfree(tk);
}
static struct trace_kprobe *find_trace_kprobe(const char *event,
const char *group)
{
struct trace_kprobe *tk;
list_for_each_entry(tk, &probe_list, list)
if (strcmp(ftrace_event_name(&tk->tp.call), event) == 0 &&
strcmp(tk->tp.call.class->system, group) == 0)
return tk;
return NULL;
}
/*
* Enable trace_probe
* if the file is NULL, enable "perf" handler, or enable "trace" handler.
*/
static int
enable_trace_kprobe(struct trace_kprobe *tk, struct ftrace_event_file *file)
{
int ret = 0;
if (file) {
struct event_file_link *link;
link = kmalloc(sizeof(*link), GFP_KERNEL);
if (!link) {
ret = -ENOMEM;
goto out;
}
link->file = file;
list_add_tail_rcu(&link->list, &tk->tp.files);
tk->tp.flags |= TP_FLAG_TRACE;
} else
tk->tp.flags |= TP_FLAG_PROFILE;
if (trace_probe_is_registered(&tk->tp) && !trace_kprobe_has_gone(tk)) {
if (trace_kprobe_is_return(tk))
ret = enable_kretprobe(&tk->rp);
else
ret = enable_kprobe(&tk->rp.kp);
}
out:
return ret;
}
/*
* Disable trace_probe
* if the file is NULL, disable "perf" handler, or disable "trace" handler.
*/
static int
disable_trace_kprobe(struct trace_kprobe *tk, struct ftrace_event_file *file)
{
struct event_file_link *link = NULL;
int wait = 0;
int ret = 0;
if (file) {
link = find_event_file_link(&tk->tp, file);
if (!link) {
ret = -EINVAL;
goto out;
}
list_del_rcu(&link->list);
wait = 1;
if (!list_empty(&tk->tp.files))
goto out;
tk->tp.flags &= ~TP_FLAG_TRACE;
} else
tk->tp.flags &= ~TP_FLAG_PROFILE;
if (!trace_probe_is_enabled(&tk->tp) && trace_probe_is_registered(&tk->tp)) {
if (trace_kprobe_is_return(tk))
disable_kretprobe(&tk->rp);
else
disable_kprobe(&tk->rp.kp);
wait = 1;
}
out:
if (wait) {
/*
* Synchronize with kprobe_trace_func/kretprobe_trace_func
* to ensure disabled (all running handlers are finished).
* This is not only for kfree(), but also the caller,
* trace_remove_event_call() supposes it for releasing
* event_call related objects, which will be accessed in
* the kprobe_trace_func/kretprobe_trace_func.
*/
synchronize_sched();
kfree(link); /* Ignored if link == NULL */
}
return ret;
}
/* Internal register function - just handle k*probes and flags */
static int __register_trace_kprobe(struct trace_kprobe *tk)
{
int i, ret;
if (trace_probe_is_registered(&tk->tp))
return -EINVAL;
for (i = 0; i < tk->tp.nr_args; i++)
traceprobe_update_arg(&tk->tp.args[i]);
/* Set/clear disabled flag according to tp->flag */
if (trace_probe_is_enabled(&tk->tp))
tk->rp.kp.flags &= ~KPROBE_FLAG_DISABLED;
else
tk->rp.kp.flags |= KPROBE_FLAG_DISABLED;
if (trace_kprobe_is_return(tk))
ret = register_kretprobe(&tk->rp);
else
ret = register_kprobe(&tk->rp.kp);
if (ret == 0)
tk->tp.flags |= TP_FLAG_REGISTERED;
else {
pr_warning("Could not insert probe at %s+%lu: %d\n",
trace_kprobe_symbol(tk), trace_kprobe_offset(tk), ret);
if (ret == -ENOENT && trace_kprobe_is_on_module(tk)) {
pr_warning("This probe might be able to register after"
"target module is loaded. Continue.\n");
ret = 0;
} else if (ret == -EILSEQ) {
pr_warning("Probing address(0x%p) is not an "
"instruction boundary.\n",
tk->rp.kp.addr);
ret = -EINVAL;
}
}
return ret;
}
/* Internal unregister function - just handle k*probes and flags */
static void __unregister_trace_kprobe(struct trace_kprobe *tk)
{
if (trace_probe_is_registered(&tk->tp)) {
if (trace_kprobe_is_return(tk))
unregister_kretprobe(&tk->rp);
else
unregister_kprobe(&tk->rp.kp);
tk->tp.flags &= ~TP_FLAG_REGISTERED;
/* Cleanup kprobe for reuse */
if (tk->rp.kp.symbol_name)
tk->rp.kp.addr = NULL;
}
}
/* Unregister a trace_probe and probe_event: call with locking probe_lock */
static int unregister_trace_kprobe(struct trace_kprobe *tk)
{
/* Enabled event can not be unregistered */
if (trace_probe_is_enabled(&tk->tp))
return -EBUSY;
/* Will fail if probe is being used by ftrace or perf */
if (unregister_kprobe_event(tk))
return -EBUSY;
__unregister_trace_kprobe(tk);
list_del(&tk->list);
return 0;
}
/* Register a trace_probe and probe_event */
static int register_trace_kprobe(struct trace_kprobe *tk)
{
struct trace_kprobe *old_tk;
int ret;
mutex_lock(&probe_lock);
/* Delete old (same name) event if exist */
old_tk = find_trace_kprobe(ftrace_event_name(&tk->tp.call),
tk->tp.call.class->system);
if (old_tk) {
ret = unregister_trace_kprobe(old_tk);
if (ret < 0)
goto end;
free_trace_kprobe(old_tk);
}
/* Register new event */
ret = register_kprobe_event(tk);
if (ret) {
pr_warning("Failed to register probe event(%d)\n", ret);
goto end;
}
/* Register k*probe */
ret = __register_trace_kprobe(tk);
if (ret < 0)
unregister_kprobe_event(tk);
else
list_add_tail(&tk->list, &probe_list);
end:
mutex_unlock(&probe_lock);
return ret;
}
/* Module notifier call back, checking event on the module */
static int trace_kprobe_module_callback(struct notifier_block *nb,
unsigned long val, void *data)
{
struct module *mod = data;
struct trace_kprobe *tk;
int ret;
if (val != MODULE_STATE_COMING)
return NOTIFY_DONE;
/* Update probes on coming module */
mutex_lock(&probe_lock);
list_for_each_entry(tk, &probe_list, list) {
if (trace_kprobe_within_module(tk, mod)) {
/* Don't need to check busy - this should have gone. */
__unregister_trace_kprobe(tk);
ret = __register_trace_kprobe(tk);
if (ret)
pr_warning("Failed to re-register probe %s on"
"%s: %d\n",
ftrace_event_name(&tk->tp.call),
mod->name, ret);
}
}
mutex_unlock(&probe_lock);
return NOTIFY_DONE;
}
static struct notifier_block trace_kprobe_module_nb = {
.notifier_call = trace_kprobe_module_callback,
.priority = 1 /* Invoked after kprobe module callback */
};
static int create_trace_kprobe(int argc, char **argv)
{
/*
* Argument syntax:
* - Add kprobe: p[:[GRP/]EVENT] [MOD:]KSYM[+OFFS]|KADDR [FETCHARGS]
* - Add kretprobe: r[:[GRP/]EVENT] [MOD:]KSYM[+0] [FETCHARGS]
* Fetch args:
* $retval : fetch return value
* $stack : fetch stack address
* $stackN : fetch Nth of stack (N:0-)
* @ADDR : fetch memory at ADDR (ADDR should be in kernel)
* @SYM[+|-offs] : fetch memory at SYM +|- offs (SYM is a data symbol)
* %REG : fetch register REG
* Dereferencing memory fetch:
* +|-offs(ARG) : fetch memory at ARG +|- offs address.
* Alias name of args:
* NAME=FETCHARG : set NAME as alias of FETCHARG.
* Type of args:
* FETCHARG:TYPE : use TYPE instead of unsigned long.
*/
struct trace_kprobe *tk;
int i, ret = 0;
bool is_return = false, is_delete = false;
char *symbol = NULL, *event = NULL, *group = NULL;
char *arg;
unsigned long offset = 0;
void *addr = NULL;
char buf[MAX_EVENT_NAME_LEN];
/* argc must be >= 1 */
if (argv[0][0] == 'p')
is_return = false;
else if (argv[0][0] == 'r')
is_return = true;
else if (argv[0][0] == '-')
is_delete = true;
else {
pr_info("Probe definition must be started with 'p', 'r' or"
" '-'.\n");
return -EINVAL;
}
if (argv[0][1] == ':') {
event = &argv[0][2];
if (strchr(event, '/')) {
group = event;
event = strchr(group, '/') + 1;
event[-1] = '\0';
if (strlen(group) == 0) {
pr_info("Group name is not specified\n");
return -EINVAL;
}
}
if (strlen(event) == 0) {
pr_info("Event name is not specified\n");
return -EINVAL;
}
}
if (!group)
group = KPROBE_EVENT_SYSTEM;
if (is_delete) {
if (!event) {
pr_info("Delete command needs an event name.\n");
return -EINVAL;
}
mutex_lock(&probe_lock);
tk = find_trace_kprobe(event, group);
if (!tk) {
mutex_unlock(&probe_lock);
pr_info("Event %s/%s doesn't exist.\n", group, event);
return -ENOENT;
}
/* delete an event */
ret = unregister_trace_kprobe(tk);
if (ret == 0)
free_trace_kprobe(tk);
mutex_unlock(&probe_lock);
return ret;
}
if (argc < 2) {
pr_info("Probe point is not specified.\n");
return -EINVAL;
}
if (isdigit(argv[1][0])) {
if (is_return) {
pr_info("Return probe point must be a symbol.\n");
return -EINVAL;
}
/* an address specified */
ret = kstrtoul(&argv[1][0], 0, (unsigned long *)&addr);
if (ret) {
pr_info("Failed to parse address.\n");
return ret;
}
} else {
/* a symbol specified */
symbol = argv[1];
/* TODO: support .init module functions */
ret = traceprobe_split_symbol_offset(symbol, &offset);
if (ret) {
pr_info("Failed to parse symbol.\n");
return ret;
}
if (offset && is_return) {
pr_info("Return probe must be used without offset.\n");
return -EINVAL;
}
}
argc -= 2; argv += 2;
/* setup a probe */
if (!event) {
/* Make a new event name */
if (symbol)
snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%s_%ld",
is_return ? 'r' : 'p', symbol, offset);
else
snprintf(buf, MAX_EVENT_NAME_LEN, "%c_0x%p",
is_return ? 'r' : 'p', addr);
event = buf;
}
tk = alloc_trace_kprobe(group, event, addr, symbol, offset, argc,
is_return);
if (IS_ERR(tk)) {
pr_info("Failed to allocate trace_probe.(%d)\n",
(int)PTR_ERR(tk));
return PTR_ERR(tk);
}
/* parse arguments */
ret = 0;
for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
struct probe_arg *parg = &tk->tp.args[i];
/* Increment count for freeing args in error case */
tk->tp.nr_args++;
/* Parse argument name */
arg = strchr(argv[i], '=');
if (arg) {
*arg++ = '\0';
parg->name = kstrdup(argv[i], GFP_KERNEL);
} else {
arg = argv[i];
/* If argument name is omitted, set "argN" */
snprintf(buf, MAX_EVENT_NAME_LEN, "arg%d", i + 1);
parg->name = kstrdup(buf, GFP_KERNEL);
}
if (!parg->name) {
pr_info("Failed to allocate argument[%d] name.\n", i);
ret = -ENOMEM;
goto error;
}
if (!is_good_name(parg->name)) {
pr_info("Invalid argument[%d] name: %s\n",
i, parg->name);
ret = -EINVAL;
goto error;
}
if (traceprobe_conflict_field_name(parg->name,
tk->tp.args, i)) {
pr_info("Argument[%d] name '%s' conflicts with "
"another field.\n", i, argv[i]);
ret = -EINVAL;
goto error;
}
/* Parse fetch argument */
ret = traceprobe_parse_probe_arg(arg, &tk->tp.size, parg,
is_return, true);
if (ret) {
pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
goto error;
}
}
ret = register_trace_kprobe(tk);
if (ret)
goto error;
return 0;
error:
free_trace_kprobe(tk);
return ret;
}
static int release_all_trace_kprobes(void)
{
struct trace_kprobe *tk;
int ret = 0;
mutex_lock(&probe_lock);
/* Ensure no probe is in use. */
list_for_each_entry(tk, &probe_list, list)
if (trace_probe_is_enabled(&tk->tp)) {
ret = -EBUSY;
goto end;
}
/* TODO: Use batch unregistration */
while (!list_empty(&probe_list)) {
tk = list_entry(probe_list.next, struct trace_kprobe, list);
ret = unregister_trace_kprobe(tk);
if (ret)
goto end;
free_trace_kprobe(tk);
}
end:
mutex_unlock(&probe_lock);
return ret;
}
/* Probes listing interfaces */
static void *probes_seq_start(struct seq_file *m, loff_t *pos)
{
mutex_lock(&probe_lock);
return seq_list_start(&probe_list, *pos);
}
static void *probes_seq_next(struct seq_file *m, void *v, loff_t *pos)
{
return seq_list_next(v, &probe_list, pos);
}
static void probes_seq_stop(struct seq_file *m, void *v)
{
mutex_unlock(&probe_lock);
}
static int probes_seq_show(struct seq_file *m, void *v)
{
struct trace_kprobe *tk = v;
int i;
seq_putc(m, trace_kprobe_is_return(tk) ? 'r' : 'p');
seq_printf(m, ":%s/%s", tk->tp.call.class->system,
ftrace_event_name(&tk->tp.call));
if (!tk->symbol)
seq_printf(m, " 0x%p", tk->rp.kp.addr);
else if (tk->rp.kp.offset)
seq_printf(m, " %s+%u", trace_kprobe_symbol(tk),
tk->rp.kp.offset);
else
seq_printf(m, " %s", trace_kprobe_symbol(tk));
for (i = 0; i < tk->tp.nr_args; i++)
seq_printf(m, " %s=%s", tk->tp.args[i].name, tk->tp.args[i].comm);
seq_putc(m, '\n');
return 0;
}
static const struct seq_operations probes_seq_op = {
.start = probes_seq_start,
.next = probes_seq_next,
.stop = probes_seq_stop,
.show = probes_seq_show
};
static int probes_open(struct inode *inode, struct file *file)
{
int ret;
if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
ret = release_all_trace_kprobes();
if (ret < 0)
return ret;
}
return seq_open(file, &probes_seq_op);
}
static ssize_t probes_write(struct file *file, const char __user *buffer,
size_t count, loff_t *ppos)
{
return traceprobe_probes_write(file, buffer, count, ppos,
create_trace_kprobe);
}
static const struct file_operations kprobe_events_ops = {
.owner = THIS_MODULE,
.open = probes_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
.write = probes_write,
};
/* Probes profiling interfaces */
static int probes_profile_seq_show(struct seq_file *m, void *v)
{
struct trace_kprobe *tk = v;
seq_printf(m, " %-44s %15lu %15lu\n",
ftrace_event_name(&tk->tp.call), tk->nhit,
tk->rp.kp.nmissed);
return 0;
}
static const struct seq_operations profile_seq_op = {
.start = probes_seq_start,
.next = probes_seq_next,
.stop = probes_seq_stop,
.show = probes_profile_seq_show
};
static int profile_open(struct inode *inode, struct file *file)
{
return seq_open(file, &profile_seq_op);
}
static const struct file_operations kprobe_profile_ops = {
.owner = THIS_MODULE,
.open = profile_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};
/* Kprobe handler */
static nokprobe_inline void
__kprobe_trace_func(struct trace_kprobe *tk, struct pt_regs *regs,
struct ftrace_event_file *ftrace_file)
{
struct kprobe_trace_entry_head *entry;
struct ring_buffer_event *event;
struct ring_buffer *buffer;
int size, dsize, pc;
unsigned long irq_flags;
struct ftrace_event_call *call = &tk->tp.call;
WARN_ON(call != ftrace_file->event_call);
if (ftrace_trigger_soft_disabled(ftrace_file))
return;
local_save_flags(irq_flags);
pc = preempt_count();
dsize = __get_data_size(&tk->tp, regs);
size = sizeof(*entry) + tk->tp.size + dsize;
event = trace_event_buffer_lock_reserve(&buffer, ftrace_file,
call->event.type,
size, irq_flags, pc);
if (!event)
return;
entry = ring_buffer_event_data(event);
entry->ip = (unsigned long)tk->rp.kp.addr;
store_trace_args(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], dsize);
event_trigger_unlock_commit_regs(ftrace_file, buffer, event,
entry, irq_flags, pc, regs);
}
static void
kprobe_trace_func(struct trace_kprobe *tk, struct pt_regs *regs)
{
struct event_file_link *link;
list_for_each_entry_rcu(link, &tk->tp.files, list)
__kprobe_trace_func(tk, regs, link->file);
}
NOKPROBE_SYMBOL(kprobe_trace_func);
/* Kretprobe handler */
static nokprobe_inline void
__kretprobe_trace_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
struct pt_regs *regs,
struct ftrace_event_file *ftrace_file)
{
struct kretprobe_trace_entry_head *entry;
struct ring_buffer_event *event;
struct ring_buffer *buffer;
int size, pc, dsize;
unsigned long irq_flags;
struct ftrace_event_call *call = &tk->tp.call;
WARN_ON(call != ftrace_file->event_call);
if (ftrace_trigger_soft_disabled(ftrace_file))
return;
local_save_flags(irq_flags);
pc = preempt_count();
dsize = __get_data_size(&tk->tp, regs);
size = sizeof(*entry) + tk->tp.size + dsize;
event = trace_event_buffer_lock_reserve(&buffer, ftrace_file,
call->event.type,
size, irq_flags, pc);
if (!event)
return;
entry = ring_buffer_event_data(event);
entry->func = (unsigned long)tk->rp.kp.addr;
entry->ret_ip = (unsigned long)ri->ret_addr;
store_trace_args(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], dsize);
event_trigger_unlock_commit_regs(ftrace_file, buffer, event,
entry, irq_flags, pc, regs);
}
static void
kretprobe_trace_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
struct pt_regs *regs)
{
struct event_file_link *link;
list_for_each_entry_rcu(link, &tk->tp.files, list)
__kretprobe_trace_func(tk, ri, regs, link->file);
}
NOKPROBE_SYMBOL(kretprobe_trace_func);
/* Event entry printers */
static enum print_line_t
print_kprobe_event(struct trace_iterator *iter, int flags,
struct trace_event *event)
{
struct kprobe_trace_entry_head *field;
struct trace_seq *s = &iter->seq;
struct trace_probe *tp;
u8 *data;
int i;
field = (struct kprobe_trace_entry_head *)iter->ent;
tp = container_of(event, struct trace_probe, call.event);
trace_seq_printf(s, "%s: (", ftrace_event_name(&tp->call));
if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
goto out;
trace_seq_putc(s, ')');
data = (u8 *)&field[1];
for (i = 0; i < tp->nr_args; i++)
if (!tp->args[i].type->print(s, tp->args[i].name,
data + tp->args[i].offset, field))
goto out;
trace_seq_putc(s, '\n');
out:
return trace_handle_return(s);
}
static enum print_line_t
print_kretprobe_event(struct trace_iterator *iter, int flags,
struct trace_event *event)
{
struct kretprobe_trace_entry_head *field;
struct trace_seq *s = &iter->seq;
struct trace_probe *tp;
u8 *data;
int i;
field = (struct kretprobe_trace_entry_head *)iter->ent;
tp = container_of(event, struct trace_probe, call.event);
trace_seq_printf(s, "%s: (", ftrace_event_name(&tp->call));
if (!seq_print_ip_sym(s, field->ret_ip, flags | TRACE_ITER_SYM_OFFSET))
goto out;
trace_seq_puts(s, " <- ");
if (!seq_print_ip_sym(s, field->func, flags & ~TRACE_ITER_SYM_OFFSET))
goto out;
trace_seq_putc(s, ')');
data = (u8 *)&field[1];
for (i = 0; i < tp->nr_args; i++)
if (!tp->args[i].type->print(s, tp->args[i].name,
data + tp->args[i].offset, field))
goto out;
trace_seq_putc(s, '\n');
out:
return trace_handle_return(s);
}
static int kprobe_event_define_fields(struct ftrace_event_call *event_call)
{
int ret, i;
struct kprobe_trace_entry_head field;
struct trace_kprobe *tk = (struct trace_kprobe *)event_call->data;
DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
/* Set argument names as fields */
for (i = 0; i < tk->tp.nr_args; i++) {
struct probe_arg *parg = &tk->tp.args[i];
ret = trace_define_field(event_call, parg->type->fmttype,
parg->name,
sizeof(field) + parg->offset,
parg->type->size,
parg->type->is_signed,
FILTER_OTHER);
if (ret)
return ret;
}
return 0;
}
static int kretprobe_event_define_fields(struct ftrace_event_call *event_call)
{
int ret, i;
struct kretprobe_trace_entry_head field;
struct trace_kprobe *tk = (struct trace_kprobe *)event_call->data;
DEFINE_FIELD(unsigned long, func, FIELD_STRING_FUNC, 0);
DEFINE_FIELD(unsigned long, ret_ip, FIELD_STRING_RETIP, 0);
/* Set argument names as fields */
for (i = 0; i < tk->tp.nr_args; i++) {
struct probe_arg *parg = &tk->tp.args[i];
ret = trace_define_field(event_call, parg->type->fmttype,
parg->name,
sizeof(field) + parg->offset,
parg->type->size,
parg->type->is_signed,
FILTER_OTHER);
if (ret)
return ret;
}
return 0;
}
#ifdef CONFIG_PERF_EVENTS
/* Kprobe profile handler */
static void
kprobe_perf_func(struct trace_kprobe *tk, struct pt_regs *regs)
{
struct ftrace_event_call *call = &tk->tp.call;
struct kprobe_trace_entry_head *entry;
struct hlist_head *head;
int size, __size, dsize;
int rctx;
head = this_cpu_ptr(call->perf_events);
if (hlist_empty(head))
return;
dsize = __get_data_size(&tk->tp, regs);
__size = sizeof(*entry) + tk->tp.size + dsize;
size = ALIGN(__size + sizeof(u32), sizeof(u64));
size -= sizeof(u32);
entry = perf_trace_buf_prepare(size, call->event.type, NULL, &rctx);
if (!entry)
return;
entry->ip = (unsigned long)tk->rp.kp.addr;
memset(&entry[1], 0, dsize);
store_trace_args(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], dsize);
perf_trace_buf_submit(entry, size, rctx, 0, 1, regs, head, NULL);
}
NOKPROBE_SYMBOL(kprobe_perf_func);
/* Kretprobe profile handler */
static void
kretprobe_perf_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
struct pt_regs *regs)
{
struct ftrace_event_call *call = &tk->tp.call;
struct kretprobe_trace_entry_head *entry;
struct hlist_head *head;
int size, __size, dsize;
int rctx;
head = this_cpu_ptr(call->perf_events);
if (hlist_empty(head))
return;
dsize = __get_data_size(&tk->tp, regs);
__size = sizeof(*entry) + tk->tp.size + dsize;
size = ALIGN(__size + sizeof(u32), sizeof(u64));
size -= sizeof(u32);
entry = perf_trace_buf_prepare(size, call->event.type, NULL, &rctx);
if (!entry)
return;
entry->func = (unsigned long)tk->rp.kp.addr;
entry->ret_ip = (unsigned long)ri->ret_addr;
store_trace_args(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], dsize);
perf_trace_buf_submit(entry, size, rctx, 0, 1, regs, head, NULL);
}
NOKPROBE_SYMBOL(kretprobe_perf_func);
#endif /* CONFIG_PERF_EVENTS */
/*
* called by perf_trace_init() or __ftrace_set_clr_event() under event_mutex.
*
* kprobe_trace_self_tests_init() does enable_trace_probe/disable_trace_probe
* lockless, but we can't race with this __init function.
*/
static int kprobe_register(struct ftrace_event_call *event,
enum trace_reg type, void *data)
{
struct trace_kprobe *tk = (struct trace_kprobe *)event->data;
struct ftrace_event_file *file = data;
switch (type) {
case TRACE_REG_REGISTER:
return enable_trace_kprobe(tk, file);
case TRACE_REG_UNREGISTER:
return disable_trace_kprobe(tk, file);
#ifdef CONFIG_PERF_EVENTS
case TRACE_REG_PERF_REGISTER:
return enable_trace_kprobe(tk, NULL);
case TRACE_REG_PERF_UNREGISTER:
return disable_trace_kprobe(tk, NULL);
case TRACE_REG_PERF_OPEN:
case TRACE_REG_PERF_CLOSE:
case TRACE_REG_PERF_ADD:
case TRACE_REG_PERF_DEL:
return 0;
#endif
}
return 0;
}
static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs)
{
struct trace_kprobe *tk = container_of(kp, struct trace_kprobe, rp.kp);
tk->nhit++;
if (tk->tp.flags & TP_FLAG_TRACE)
kprobe_trace_func(tk, regs);
#ifdef CONFIG_PERF_EVENTS
if (tk->tp.flags & TP_FLAG_PROFILE)
kprobe_perf_func(tk, regs);
#endif
return 0; /* We don't tweek kernel, so just return 0 */
}
NOKPROBE_SYMBOL(kprobe_dispatcher);
static int
kretprobe_dispatcher(struct kretprobe_instance *ri, struct pt_regs *regs)
{
struct trace_kprobe *tk = container_of(ri->rp, struct trace_kprobe, rp);
tk->nhit++;
if (tk->tp.flags & TP_FLAG_TRACE)
kretprobe_trace_func(tk, ri, regs);
#ifdef CONFIG_PERF_EVENTS
if (tk->tp.flags & TP_FLAG_PROFILE)
kretprobe_perf_func(tk, ri, regs);
#endif
return 0; /* We don't tweek kernel, so just return 0 */
}
NOKPROBE_SYMBOL(kretprobe_dispatcher);
static struct trace_event_functions kretprobe_funcs = {
.trace = print_kretprobe_event
};
static struct trace_event_functions kprobe_funcs = {
.trace = print_kprobe_event
};
static int register_kprobe_event(struct trace_kprobe *tk)
{
struct ftrace_event_call *call = &tk->tp.call;
int ret;
/* Initialize ftrace_event_call */
INIT_LIST_HEAD(&call->class->fields);
if (trace_kprobe_is_return(tk)) {
call->event.funcs = &kretprobe_funcs;
call->class->define_fields = kretprobe_event_define_fields;
} else {
call->event.funcs = &kprobe_funcs;
call->class->define_fields = kprobe_event_define_fields;
}
if (set_print_fmt(&tk->tp, trace_kprobe_is_return(tk)) < 0)
return -ENOMEM;
ret = register_ftrace_event(&call->event);
if (!ret) {
kfree(call->print_fmt);
return -ENODEV;
}
call->flags = 0;
call->class->reg = kprobe_register;
call->data = tk;
ret = trace_add_event_call(call);
if (ret) {
pr_info("Failed to register kprobe event: %s\n",
ftrace_event_name(call));
kfree(call->print_fmt);
unregister_ftrace_event(&call->event);
}
return ret;
}
static int unregister_kprobe_event(struct trace_kprobe *tk)
{
int ret;
/* tp->event is unregistered in trace_remove_event_call() */
ret = trace_remove_event_call(&tk->tp.call);
if (!ret)
kfree(tk->tp.call.print_fmt);
return ret;
}
/* Make a debugfs interface for controlling probe points */
static __init int init_kprobe_trace(void)
{
struct dentry *d_tracer;
struct dentry *entry;
if (register_module_notifier(&trace_kprobe_module_nb))
return -EINVAL;
d_tracer = tracing_init_dentry();
if (IS_ERR(d_tracer))
return 0;
entry = debugfs_create_file("kprobe_events", 0644, d_tracer,
NULL, &kprobe_events_ops);
/* Event list interface */
if (!entry)
pr_warning("Could not create debugfs "
"'kprobe_events' entry\n");
/* Profile interface */
entry = debugfs_create_file("kprobe_profile", 0444, d_tracer,
NULL, &kprobe_profile_ops);
if (!entry)
pr_warning("Could not create debugfs "
"'kprobe_profile' entry\n");
return 0;
}
fs_initcall(init_kprobe_trace);
#ifdef CONFIG_FTRACE_STARTUP_TEST
/*
* The "__used" keeps gcc from removing the function symbol
* from the kallsyms table.
*/
static __used int kprobe_trace_selftest_target(int a1, int a2, int a3,
int a4, int a5, int a6)
{
return a1 + a2 + a3 + a4 + a5 + a6;
}
static struct ftrace_event_file *
find_trace_probe_file(struct trace_kprobe *tk, struct trace_array *tr)
{
struct ftrace_event_file *file;
list_for_each_entry(file, &tr->events, list)
if (file->event_call == &tk->tp.call)
return file;
return NULL;
}
/*
* Nobody but us can call enable_trace_kprobe/disable_trace_kprobe at this
* stage, we can do this lockless.
*/
static __init int kprobe_trace_self_tests_init(void)
{
int ret, warn = 0;
int (*target)(int, int, int, int, int, int);
struct trace_kprobe *tk;
struct ftrace_event_file *file;
if (tracing_is_disabled())
return -ENODEV;
target = kprobe_trace_selftest_target;
pr_info("Testing kprobe tracing: ");
ret = traceprobe_command("p:testprobe kprobe_trace_selftest_target "
"$stack $stack0 +0($stack)",
create_trace_kprobe);
if (WARN_ON_ONCE(ret)) {
pr_warn("error on probing function entry.\n");
warn++;
} else {
/* Enable trace point */
tk = find_trace_kprobe("testprobe", KPROBE_EVENT_SYSTEM);
if (WARN_ON_ONCE(tk == NULL)) {
pr_warn("error on getting new probe.\n");
warn++;
} else {
file = find_trace_probe_file(tk, top_trace_array());
if (WARN_ON_ONCE(file == NULL)) {
pr_warn("error on getting probe file.\n");
warn++;
} else
enable_trace_kprobe(tk, file);
}
}
ret = traceprobe_command("r:testprobe2 kprobe_trace_selftest_target "
"$retval", create_trace_kprobe);
if (WARN_ON_ONCE(ret)) {
pr_warn("error on probing function return.\n");
warn++;
} else {
/* Enable trace point */
tk = find_trace_kprobe("testprobe2", KPROBE_EVENT_SYSTEM);
if (WARN_ON_ONCE(tk == NULL)) {
pr_warn("error on getting 2nd new probe.\n");
warn++;
} else {
file = find_trace_probe_file(tk, top_trace_array());
if (WARN_ON_ONCE(file == NULL)) {
pr_warn("error on getting probe file.\n");
warn++;
} else
enable_trace_kprobe(tk, file);
}
}
if (warn)
goto end;
ret = target(1, 2, 3, 4, 5, 6);
/* Disable trace points before removing it */
tk = find_trace_kprobe("testprobe", KPROBE_EVENT_SYSTEM);
if (WARN_ON_ONCE(tk == NULL)) {
pr_warn("error on getting test probe.\n");
warn++;
} else {
file = find_trace_probe_file(tk, top_trace_array());
if (WARN_ON_ONCE(file == NULL)) {
pr_warn("error on getting probe file.\n");
warn++;
} else
disable_trace_kprobe(tk, file);
}
tk = find_trace_kprobe("testprobe2", KPROBE_EVENT_SYSTEM);
if (WARN_ON_ONCE(tk == NULL)) {
pr_warn("error on getting 2nd test probe.\n");
warn++;
} else {
file = find_trace_probe_file(tk, top_trace_array());
if (WARN_ON_ONCE(file == NULL)) {
pr_warn("error on getting probe file.\n");
warn++;
} else
disable_trace_kprobe(tk, file);
}
ret = traceprobe_command("-:testprobe", create_trace_kprobe);
if (WARN_ON_ONCE(ret)) {
pr_warn("error on deleting a probe.\n");
warn++;
}
ret = traceprobe_command("-:testprobe2", create_trace_kprobe);
if (WARN_ON_ONCE(ret)) {
pr_warn("error on deleting a probe.\n");
warn++;
}
end:
release_all_trace_kprobes();
if (warn)
pr_cont("NG: Some tests are failed. Please check them.\n");
else
pr_cont("OK\n");
return 0;
}
late_initcall(kprobe_trace_self_tests_init);
#endif