linux/kernel/trace/trace_kprobe.c
Masami Hiramatsu (Google) 25f00e40ce tracing/probes: Support $argN in return probe (kprobe and fprobe)
Support accessing $argN in the return probe events. This will help users to
record entry data in function return (exit) event for simplfing the function
entry/exit information in one event, and record the result values (e.g.
allocated object/initialized object) at function exit.

For example, if we have a function `int init_foo(struct foo *obj, int param)`
sometimes we want to check how `obj` is initialized. In such case, we can
define a new return event like below;

 # echo 'r init_foo retval=$retval param=$arg2 field1=+0($arg1)' >> kprobe_events

Thus it records the function parameter `param` and its result `obj->field1`
(the dereference will be done in the function exit timing) value at once.

This also support fprobe, BTF args and'$arg*'. So if CONFIG_DEBUG_INFO_BTF
is enabled, we can trace both function parameters and the return value
by following command.

 # echo 'f target_function%return $arg* $retval' >> dynamic_events

Link: https://lore.kernel.org/all/170952365552.229804.224112990211602895.stgit@devnote2/

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
2024-03-07 00:27:34 +09:00

2128 lines
51 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Kprobes-based tracing events
*
* Created by Masami Hiramatsu <mhiramat@redhat.com>
*
*/
#define pr_fmt(fmt) "trace_kprobe: " fmt
#include <linux/bpf-cgroup.h>
#include <linux/security.h>
#include <linux/module.h>
#include <linux/uaccess.h>
#include <linux/rculist.h>
#include <linux/error-injection.h>
#include <asm/setup.h> /* for COMMAND_LINE_SIZE */
#include "trace_dynevent.h"
#include "trace_kprobe_selftest.h"
#include "trace_probe.h"
#include "trace_probe_tmpl.h"
#include "trace_probe_kernel.h"
#define KPROBE_EVENT_SYSTEM "kprobes"
#define KRETPROBE_MAXACTIVE_MAX 4096
/* Kprobe early definition from command line */
static char kprobe_boot_events_buf[COMMAND_LINE_SIZE] __initdata;
static int __init set_kprobe_boot_events(char *str)
{
strscpy(kprobe_boot_events_buf, str, COMMAND_LINE_SIZE);
disable_tracing_selftest("running kprobe events");
return 1;
}
__setup("kprobe_event=", set_kprobe_boot_events);
static int trace_kprobe_create(const char *raw_command);
static int trace_kprobe_show(struct seq_file *m, struct dyn_event *ev);
static int trace_kprobe_release(struct dyn_event *ev);
static bool trace_kprobe_is_busy(struct dyn_event *ev);
static bool trace_kprobe_match(const char *system, const char *event,
int argc, const char **argv, struct dyn_event *ev);
static struct dyn_event_operations trace_kprobe_ops = {
.create = trace_kprobe_create,
.show = trace_kprobe_show,
.is_busy = trace_kprobe_is_busy,
.free = trace_kprobe_release,
.match = trace_kprobe_match,
};
/*
* Kprobe event core functions
*/
struct trace_kprobe {
struct dyn_event devent;
struct kretprobe rp; /* Use rp.kp for kprobe use */
unsigned long __percpu *nhit;
const char *symbol; /* symbol name */
struct trace_probe tp;
};
static bool is_trace_kprobe(struct dyn_event *ev)
{
return ev->ops == &trace_kprobe_ops;
}
static struct trace_kprobe *to_trace_kprobe(struct dyn_event *ev)
{
return container_of(ev, struct trace_kprobe, devent);
}
/**
* for_each_trace_kprobe - iterate over the trace_kprobe list
* @pos: the struct trace_kprobe * for each entry
* @dpos: the struct dyn_event * to use as a loop cursor
*/
#define for_each_trace_kprobe(pos, dpos) \
for_each_dyn_event(dpos) \
if (is_trace_kprobe(dpos) && (pos = to_trace_kprobe(dpos)))
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(module_name(mod));
const char *name = trace_kprobe_symbol(tk);
return strncmp(module_name(mod), name, len) == 0 && name[len] == ':';
}
static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk)
{
char *p;
bool ret;
if (!tk->symbol)
return false;
p = strchr(tk->symbol, ':');
if (!p)
return true;
*p = '\0';
rcu_read_lock_sched();
ret = !!find_module(tk->symbol);
rcu_read_unlock_sched();
*p = ':';
return ret;
}
static bool trace_kprobe_is_busy(struct dyn_event *ev)
{
struct trace_kprobe *tk = to_trace_kprobe(ev);
return trace_probe_is_enabled(&tk->tp);
}
static bool trace_kprobe_match_command_head(struct trace_kprobe *tk,
int argc, const char **argv)
{
char buf[MAX_ARGSTR_LEN + 1];
if (!argc)
return true;
if (!tk->symbol)
snprintf(buf, sizeof(buf), "0x%p", tk->rp.kp.addr);
else if (tk->rp.kp.offset)
snprintf(buf, sizeof(buf), "%s+%u",
trace_kprobe_symbol(tk), tk->rp.kp.offset);
else
snprintf(buf, sizeof(buf), "%s", trace_kprobe_symbol(tk));
if (strcmp(buf, argv[0]))
return false;
argc--; argv++;
return trace_probe_match_command_args(&tk->tp, argc, argv);
}
static bool trace_kprobe_match(const char *system, const char *event,
int argc, const char **argv, struct dyn_event *ev)
{
struct trace_kprobe *tk = to_trace_kprobe(ev);
return (event[0] == '\0' ||
strcmp(trace_probe_name(&tk->tp), event) == 0) &&
(!system || strcmp(trace_probe_group_name(&tk->tp), system) == 0) &&
trace_kprobe_match_command_head(tk, argc, argv);
}
static nokprobe_inline unsigned long trace_kprobe_nhit(struct trace_kprobe *tk)
{
unsigned long nhit = 0;
int cpu;
for_each_possible_cpu(cpu)
nhit += *per_cpu_ptr(tk->nhit, cpu);
return nhit;
}
static nokprobe_inline bool trace_kprobe_is_registered(struct trace_kprobe *tk)
{
return !(list_empty(&tk->rp.kp.list) &&
hlist_unhashed(&tk->rp.kp.hlist));
}
/* Return 0 if it fails to find the symbol address */
static nokprobe_inline
unsigned long trace_kprobe_address(struct trace_kprobe *tk)
{
unsigned long addr;
if (tk->symbol) {
addr = (unsigned long)
kallsyms_lookup_name(trace_kprobe_symbol(tk));
if (addr)
addr += tk->rp.kp.offset;
} else {
addr = (unsigned long)tk->rp.kp.addr;
}
return addr;
}
static nokprobe_inline struct trace_kprobe *
trace_kprobe_primary_from_call(struct trace_event_call *call)
{
struct trace_probe *tp;
tp = trace_probe_primary_from_call(call);
if (WARN_ON_ONCE(!tp))
return NULL;
return container_of(tp, struct trace_kprobe, tp);
}
bool trace_kprobe_on_func_entry(struct trace_event_call *call)
{
struct trace_kprobe *tk = trace_kprobe_primary_from_call(call);
return tk ? (kprobe_on_func_entry(tk->rp.kp.addr,
tk->rp.kp.addr ? NULL : tk->rp.kp.symbol_name,
tk->rp.kp.addr ? 0 : tk->rp.kp.offset) == 0) : false;
}
bool trace_kprobe_error_injectable(struct trace_event_call *call)
{
struct trace_kprobe *tk = trace_kprobe_primary_from_call(call);
return tk ? within_error_injection_list(trace_kprobe_address(tk)) :
false;
}
static int register_kprobe_event(struct trace_kprobe *tk);
static int unregister_kprobe_event(struct trace_kprobe *tk);
static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs);
static int kretprobe_dispatcher(struct kretprobe_instance *ri,
struct pt_regs *regs);
static void free_trace_kprobe(struct trace_kprobe *tk)
{
if (tk) {
trace_probe_cleanup(&tk->tp);
kfree(tk->symbol);
free_percpu(tk->nhit);
kfree(tk);
}
}
/*
* 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 maxactive,
int nargs, bool is_return)
{
struct trace_kprobe *tk;
int ret = -ENOMEM;
tk = kzalloc(struct_size(tk, tp.args, nargs), GFP_KERNEL);
if (!tk)
return ERR_PTR(ret);
tk->nhit = alloc_percpu(unsigned long);
if (!tk->nhit)
goto error;
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;
tk->rp.maxactive = maxactive;
INIT_HLIST_NODE(&tk->rp.kp.hlist);
INIT_LIST_HEAD(&tk->rp.kp.list);
ret = trace_probe_init(&tk->tp, event, group, false, nargs);
if (ret < 0)
goto error;
dyn_event_init(&tk->devent, &trace_kprobe_ops);
return tk;
error:
free_trace_kprobe(tk);
return ERR_PTR(ret);
}
static struct trace_kprobe *find_trace_kprobe(const char *event,
const char *group)
{
struct dyn_event *pos;
struct trace_kprobe *tk;
for_each_trace_kprobe(tk, pos)
if (strcmp(trace_probe_name(&tk->tp), event) == 0 &&
strcmp(trace_probe_group_name(&tk->tp), group) == 0)
return tk;
return NULL;
}
static inline int __enable_trace_kprobe(struct trace_kprobe *tk)
{
int ret = 0;
if (trace_kprobe_is_registered(tk) && !trace_kprobe_has_gone(tk)) {
if (trace_kprobe_is_return(tk))
ret = enable_kretprobe(&tk->rp);
else
ret = enable_kprobe(&tk->rp.kp);
}
return ret;
}
static void __disable_trace_kprobe(struct trace_probe *tp)
{
struct trace_kprobe *tk;
list_for_each_entry(tk, trace_probe_probe_list(tp), tp.list) {
if (!trace_kprobe_is_registered(tk))
continue;
if (trace_kprobe_is_return(tk))
disable_kretprobe(&tk->rp);
else
disable_kprobe(&tk->rp.kp);
}
}
/*
* Enable trace_probe
* if the file is NULL, enable "perf" handler, or enable "trace" handler.
*/
static int enable_trace_kprobe(struct trace_event_call *call,
struct trace_event_file *file)
{
struct trace_probe *tp;
struct trace_kprobe *tk;
bool enabled;
int ret = 0;
tp = trace_probe_primary_from_call(call);
if (WARN_ON_ONCE(!tp))
return -ENODEV;
enabled = trace_probe_is_enabled(tp);
/* This also changes "enabled" state */
if (file) {
ret = trace_probe_add_file(tp, file);
if (ret)
return ret;
} else
trace_probe_set_flag(tp, TP_FLAG_PROFILE);
if (enabled)
return 0;
list_for_each_entry(tk, trace_probe_probe_list(tp), tp.list) {
if (trace_kprobe_has_gone(tk))
continue;
ret = __enable_trace_kprobe(tk);
if (ret)
break;
enabled = true;
}
if (ret) {
/* Failed to enable one of them. Roll back all */
if (enabled)
__disable_trace_kprobe(tp);
if (file)
trace_probe_remove_file(tp, file);
else
trace_probe_clear_flag(tp, TP_FLAG_PROFILE);
}
return ret;
}
/*
* Disable trace_probe
* if the file is NULL, disable "perf" handler, or disable "trace" handler.
*/
static int disable_trace_kprobe(struct trace_event_call *call,
struct trace_event_file *file)
{
struct trace_probe *tp;
tp = trace_probe_primary_from_call(call);
if (WARN_ON_ONCE(!tp))
return -ENODEV;
if (file) {
if (!trace_probe_get_file_link(tp, file))
return -ENOENT;
if (!trace_probe_has_single_file(tp))
goto out;
trace_probe_clear_flag(tp, TP_FLAG_TRACE);
} else
trace_probe_clear_flag(tp, TP_FLAG_PROFILE);
if (!trace_probe_is_enabled(tp))
__disable_trace_kprobe(tp);
out:
if (file)
/*
* Synchronization is done in below function. For perf event,
* file == NULL and perf_trace_event_unreg() calls
* tracepoint_synchronize_unregister() to ensure synchronize
* event. We don't need to care about it.
*/
trace_probe_remove_file(tp, file);
return 0;
}
#if defined(CONFIG_DYNAMIC_FTRACE) && \
!defined(CONFIG_KPROBE_EVENTS_ON_NOTRACE)
static bool __within_notrace_func(unsigned long addr)
{
unsigned long offset, size;
if (!addr || !kallsyms_lookup_size_offset(addr, &size, &offset))
return false;
/* Get the entry address of the target function */
addr -= offset;
/*
* Since ftrace_location_range() does inclusive range check, we need
* to subtract 1 byte from the end address.
*/
return !ftrace_location_range(addr, addr + size - 1);
}
static bool within_notrace_func(struct trace_kprobe *tk)
{
unsigned long addr = trace_kprobe_address(tk);
char symname[KSYM_NAME_LEN], *p;
if (!__within_notrace_func(addr))
return false;
/* Check if the address is on a suffixed-symbol */
if (!lookup_symbol_name(addr, symname)) {
p = strchr(symname, '.');
if (!p)
return true;
*p = '\0';
addr = (unsigned long)kprobe_lookup_name(symname, 0);
if (addr)
return __within_notrace_func(addr);
}
return true;
}
#else
#define within_notrace_func(tk) (false)
#endif
/* Internal register function - just handle k*probes and flags */
static int __register_trace_kprobe(struct trace_kprobe *tk)
{
int i, ret;
ret = security_locked_down(LOCKDOWN_KPROBES);
if (ret)
return ret;
if (trace_kprobe_is_registered(tk))
return -EINVAL;
if (within_notrace_func(tk)) {
pr_warn("Could not probe notrace function %ps\n",
(void *)trace_kprobe_address(tk));
return -EINVAL;
}
for (i = 0; i < tk->tp.nr_args; i++) {
ret = traceprobe_update_arg(&tk->tp.args[i]);
if (ret)
return ret;
}
/* 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);
return ret;
}
/* Internal unregister function - just handle k*probes and flags */
static void __unregister_trace_kprobe(struct trace_kprobe *tk)
{
if (trace_kprobe_is_registered(tk)) {
if (trace_kprobe_is_return(tk))
unregister_kretprobe(&tk->rp);
else
unregister_kprobe(&tk->rp.kp);
/* Cleanup kprobe for reuse and mark it unregistered */
INIT_HLIST_NODE(&tk->rp.kp.hlist);
INIT_LIST_HEAD(&tk->rp.kp.list);
if (tk->rp.kp.symbol_name)
tk->rp.kp.addr = NULL;
}
}
/* Unregister a trace_probe and probe_event */
static int unregister_trace_kprobe(struct trace_kprobe *tk)
{
/* If other probes are on the event, just unregister kprobe */
if (trace_probe_has_sibling(&tk->tp))
goto unreg;
/* Enabled event can not be unregistered */
if (trace_probe_is_enabled(&tk->tp))
return -EBUSY;
/* If there's a reference to the dynamic event */
if (trace_event_dyn_busy(trace_probe_event_call(&tk->tp)))
return -EBUSY;
/* Will fail if probe is being used by ftrace or perf */
if (unregister_kprobe_event(tk))
return -EBUSY;
unreg:
__unregister_trace_kprobe(tk);
dyn_event_remove(&tk->devent);
trace_probe_unlink(&tk->tp);
return 0;
}
static bool trace_kprobe_has_same_kprobe(struct trace_kprobe *orig,
struct trace_kprobe *comp)
{
struct trace_probe_event *tpe = orig->tp.event;
int i;
list_for_each_entry(orig, &tpe->probes, tp.list) {
if (strcmp(trace_kprobe_symbol(orig),
trace_kprobe_symbol(comp)) ||
trace_kprobe_offset(orig) != trace_kprobe_offset(comp))
continue;
/*
* trace_probe_compare_arg_type() ensured that nr_args and
* each argument name and type are same. Let's compare comm.
*/
for (i = 0; i < orig->tp.nr_args; i++) {
if (strcmp(orig->tp.args[i].comm,
comp->tp.args[i].comm))
break;
}
if (i == orig->tp.nr_args)
return true;
}
return false;
}
static int append_trace_kprobe(struct trace_kprobe *tk, struct trace_kprobe *to)
{
int ret;
ret = trace_probe_compare_arg_type(&tk->tp, &to->tp);
if (ret) {
/* Note that argument starts index = 2 */
trace_probe_log_set_index(ret + 1);
trace_probe_log_err(0, DIFF_ARG_TYPE);
return -EEXIST;
}
if (trace_kprobe_has_same_kprobe(to, tk)) {
trace_probe_log_set_index(0);
trace_probe_log_err(0, SAME_PROBE);
return -EEXIST;
}
/* Append to existing event */
ret = trace_probe_append(&tk->tp, &to->tp);
if (ret)
return ret;
/* Register k*probe */
ret = __register_trace_kprobe(tk);
if (ret == -ENOENT && !trace_kprobe_module_exist(tk)) {
pr_warn("This probe might be able to register after target module is loaded. Continue.\n");
ret = 0;
}
if (ret)
trace_probe_unlink(&tk->tp);
else
dyn_event_add(&tk->devent, trace_probe_event_call(&tk->tp));
return ret;
}
/* 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(&event_mutex);
old_tk = find_trace_kprobe(trace_probe_name(&tk->tp),
trace_probe_group_name(&tk->tp));
if (old_tk) {
if (trace_kprobe_is_return(tk) != trace_kprobe_is_return(old_tk)) {
trace_probe_log_set_index(0);
trace_probe_log_err(0, DIFF_PROBE_TYPE);
ret = -EEXIST;
} else {
ret = append_trace_kprobe(tk, old_tk);
}
goto end;
}
/* Register new event */
ret = register_kprobe_event(tk);
if (ret) {
if (ret == -EEXIST) {
trace_probe_log_set_index(0);
trace_probe_log_err(0, EVENT_EXIST);
} else
pr_warn("Failed to register probe event(%d)\n", ret);
goto end;
}
/* Register k*probe */
ret = __register_trace_kprobe(tk);
if (ret == -ENOENT && !trace_kprobe_module_exist(tk)) {
pr_warn("This probe might be able to register after target module is loaded. Continue.\n");
ret = 0;
}
if (ret < 0)
unregister_kprobe_event(tk);
else
dyn_event_add(&tk->devent, trace_probe_event_call(&tk->tp));
end:
mutex_unlock(&event_mutex);
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 dyn_event *pos;
struct trace_kprobe *tk;
int ret;
if (val != MODULE_STATE_COMING)
return NOTIFY_DONE;
/* Update probes on coming module */
mutex_lock(&event_mutex);
for_each_trace_kprobe(tk, pos) {
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_warn("Failed to re-register probe %s on %s: %d\n",
trace_probe_name(&tk->tp),
module_name(mod), ret);
}
}
mutex_unlock(&event_mutex);
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 count_symbols(void *data, unsigned long unused)
{
unsigned int *count = data;
(*count)++;
return 0;
}
struct sym_count_ctx {
unsigned int count;
const char *name;
};
static int count_mod_symbols(void *data, const char *name, unsigned long unused)
{
struct sym_count_ctx *ctx = data;
if (strcmp(name, ctx->name) == 0)
ctx->count++;
return 0;
}
static unsigned int number_of_same_symbols(char *func_name)
{
struct sym_count_ctx ctx = { .count = 0, .name = func_name };
kallsyms_on_each_match_symbol(count_symbols, func_name, &ctx.count);
module_kallsyms_on_each_symbol(NULL, count_mod_symbols, &ctx);
return ctx.count;
}
static int trace_kprobe_entry_handler(struct kretprobe_instance *ri,
struct pt_regs *regs);
static int __trace_kprobe_create(int argc, const char *argv[])
{
/*
* Argument syntax:
* - Add kprobe:
* p[:[GRP/][EVENT]] [MOD:]KSYM[+OFFS]|KADDR [FETCHARGS]
* - Add kretprobe:
* r[MAXACTIVE][:[GRP/][EVENT]] [MOD:]KSYM[+0] [FETCHARGS]
* Or
* p[:[GRP/][EVENT]] [MOD:]KSYM[+0]%return [FETCHARGS]
*
* Fetch args:
* $retval : fetch return value
* $stack : fetch stack address
* $stackN : fetch Nth of stack (N:0-)
* $comm : fetch current task comm
* @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 = NULL;
int i, len, new_argc = 0, ret = 0;
bool is_return = false;
char *symbol = NULL, *tmp = NULL;
const char **new_argv = NULL;
const char *event = NULL, *group = KPROBE_EVENT_SYSTEM;
enum probe_print_type ptype;
int maxactive = 0;
long offset = 0;
void *addr = NULL;
char buf[MAX_EVENT_NAME_LEN];
char gbuf[MAX_EVENT_NAME_LEN];
char abuf[MAX_BTF_ARGS_LEN];
struct traceprobe_parse_context ctx = { .flags = TPARG_FL_KERNEL };
switch (argv[0][0]) {
case 'r':
is_return = true;
break;
case 'p':
break;
default:
return -ECANCELED;
}
if (argc < 2)
return -ECANCELED;
trace_probe_log_init("trace_kprobe", argc, argv);
event = strchr(&argv[0][1], ':');
if (event)
event++;
if (isdigit(argv[0][1])) {
if (!is_return) {
trace_probe_log_err(1, BAD_MAXACT_TYPE);
goto parse_error;
}
if (event)
len = event - &argv[0][1] - 1;
else
len = strlen(&argv[0][1]);
if (len > MAX_EVENT_NAME_LEN - 1) {
trace_probe_log_err(1, BAD_MAXACT);
goto parse_error;
}
memcpy(buf, &argv[0][1], len);
buf[len] = '\0';
ret = kstrtouint(buf, 0, &maxactive);
if (ret || !maxactive) {
trace_probe_log_err(1, BAD_MAXACT);
goto parse_error;
}
/* kretprobes instances are iterated over via a list. The
* maximum should stay reasonable.
*/
if (maxactive > KRETPROBE_MAXACTIVE_MAX) {
trace_probe_log_err(1, MAXACT_TOO_BIG);
goto parse_error;
}
}
/* try to parse an address. if that fails, try to read the
* input as a symbol. */
if (kstrtoul(argv[1], 0, (unsigned long *)&addr)) {
trace_probe_log_set_index(1);
/* Check whether uprobe event specified */
if (strchr(argv[1], '/') && strchr(argv[1], ':')) {
ret = -ECANCELED;
goto error;
}
/* a symbol specified */
symbol = kstrdup(argv[1], GFP_KERNEL);
if (!symbol)
return -ENOMEM;
tmp = strchr(symbol, '%');
if (tmp) {
if (!strcmp(tmp, "%return")) {
*tmp = '\0';
is_return = true;
} else {
trace_probe_log_err(tmp - symbol, BAD_ADDR_SUFFIX);
goto parse_error;
}
}
/* TODO: support .init module functions */
ret = traceprobe_split_symbol_offset(symbol, &offset);
if (ret || offset < 0 || offset > UINT_MAX) {
trace_probe_log_err(0, BAD_PROBE_ADDR);
goto parse_error;
}
if (is_return)
ctx.flags |= TPARG_FL_RETURN;
ret = kprobe_on_func_entry(NULL, symbol, offset);
if (ret == 0 && !is_return)
ctx.flags |= TPARG_FL_FENTRY;
/* Defer the ENOENT case until register kprobe */
if (ret == -EINVAL && is_return) {
trace_probe_log_err(0, BAD_RETPROBE);
goto parse_error;
}
}
if (symbol && !strchr(symbol, ':')) {
unsigned int count;
count = number_of_same_symbols(symbol);
if (count > 1) {
/*
* Users should use ADDR to remove the ambiguity of
* using KSYM only.
*/
trace_probe_log_err(0, NON_UNIQ_SYMBOL);
ret = -EADDRNOTAVAIL;
goto error;
} else if (count == 0) {
/*
* We can return ENOENT earlier than when register the
* kprobe.
*/
trace_probe_log_err(0, BAD_PROBE_ADDR);
ret = -ENOENT;
goto error;
}
}
trace_probe_log_set_index(0);
if (event) {
ret = traceprobe_parse_event_name(&event, &group, gbuf,
event - argv[0]);
if (ret)
goto parse_error;
}
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);
sanitize_event_name(buf);
event = buf;
}
argc -= 2; argv += 2;
ctx.funcname = symbol;
new_argv = traceprobe_expand_meta_args(argc, argv, &new_argc,
abuf, MAX_BTF_ARGS_LEN, &ctx);
if (IS_ERR(new_argv)) {
ret = PTR_ERR(new_argv);
new_argv = NULL;
goto out;
}
if (new_argv) {
argc = new_argc;
argv = new_argv;
}
/* setup a probe */
tk = alloc_trace_kprobe(group, event, addr, symbol, offset, maxactive,
argc, is_return);
if (IS_ERR(tk)) {
ret = PTR_ERR(tk);
/* This must return -ENOMEM, else there is a bug */
WARN_ON_ONCE(ret != -ENOMEM);
goto out; /* We know tk is not allocated */
}
/* parse arguments */
for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
trace_probe_log_set_index(i + 2);
ctx.offset = 0;
ret = traceprobe_parse_probe_arg(&tk->tp, i, argv[i], &ctx);
if (ret)
goto error; /* This can be -ENOMEM */
}
/* entry handler for kretprobe */
if (is_return && tk->tp.entry_arg) {
tk->rp.entry_handler = trace_kprobe_entry_handler;
tk->rp.data_size = traceprobe_get_entry_data_size(&tk->tp);
}
ptype = is_return ? PROBE_PRINT_RETURN : PROBE_PRINT_NORMAL;
ret = traceprobe_set_print_fmt(&tk->tp, ptype);
if (ret < 0)
goto error;
ret = register_trace_kprobe(tk);
if (ret) {
trace_probe_log_set_index(1);
if (ret == -EILSEQ)
trace_probe_log_err(0, BAD_INSN_BNDRY);
else if (ret == -ENOENT)
trace_probe_log_err(0, BAD_PROBE_ADDR);
else if (ret != -ENOMEM && ret != -EEXIST)
trace_probe_log_err(0, FAIL_REG_PROBE);
goto error;
}
out:
traceprobe_finish_parse(&ctx);
trace_probe_log_clear();
kfree(new_argv);
kfree(symbol);
return ret;
parse_error:
ret = -EINVAL;
error:
free_trace_kprobe(tk);
goto out;
}
static int trace_kprobe_create(const char *raw_command)
{
return trace_probe_create(raw_command, __trace_kprobe_create);
}
static int create_or_delete_trace_kprobe(const char *raw_command)
{
int ret;
if (raw_command[0] == '-')
return dyn_event_release(raw_command, &trace_kprobe_ops);
ret = trace_kprobe_create(raw_command);
return ret == -ECANCELED ? -EINVAL : ret;
}
static int trace_kprobe_run_command(struct dynevent_cmd *cmd)
{
return create_or_delete_trace_kprobe(cmd->seq.buffer);
}
/**
* kprobe_event_cmd_init - Initialize a kprobe event command object
* @cmd: A pointer to the dynevent_cmd struct representing the new event
* @buf: A pointer to the buffer used to build the command
* @maxlen: The length of the buffer passed in @buf
*
* Initialize a synthetic event command object. Use this before
* calling any of the other kprobe_event functions.
*/
void kprobe_event_cmd_init(struct dynevent_cmd *cmd, char *buf, int maxlen)
{
dynevent_cmd_init(cmd, buf, maxlen, DYNEVENT_TYPE_KPROBE,
trace_kprobe_run_command);
}
EXPORT_SYMBOL_GPL(kprobe_event_cmd_init);
/**
* __kprobe_event_gen_cmd_start - Generate a kprobe event command from arg list
* @cmd: A pointer to the dynevent_cmd struct representing the new event
* @kretprobe: Is this a return probe?
* @name: The name of the kprobe event
* @loc: The location of the kprobe event
* @...: Variable number of arg (pairs), one pair for each field
*
* NOTE: Users normally won't want to call this function directly, but
* rather use the kprobe_event_gen_cmd_start() wrapper, which automatically
* adds a NULL to the end of the arg list. If this function is used
* directly, make sure the last arg in the variable arg list is NULL.
*
* Generate a kprobe event command to be executed by
* kprobe_event_gen_cmd_end(). This function can be used to generate the
* complete command or only the first part of it; in the latter case,
* kprobe_event_add_fields() can be used to add more fields following this.
*
* Unlikely the synth_event_gen_cmd_start(), @loc must be specified. This
* returns -EINVAL if @loc == NULL.
*
* Return: 0 if successful, error otherwise.
*/
int __kprobe_event_gen_cmd_start(struct dynevent_cmd *cmd, bool kretprobe,
const char *name, const char *loc, ...)
{
char buf[MAX_EVENT_NAME_LEN];
struct dynevent_arg arg;
va_list args;
int ret;
if (cmd->type != DYNEVENT_TYPE_KPROBE)
return -EINVAL;
if (!loc)
return -EINVAL;
if (kretprobe)
snprintf(buf, MAX_EVENT_NAME_LEN, "r:kprobes/%s", name);
else
snprintf(buf, MAX_EVENT_NAME_LEN, "p:kprobes/%s", name);
ret = dynevent_str_add(cmd, buf);
if (ret)
return ret;
dynevent_arg_init(&arg, 0);
arg.str = loc;
ret = dynevent_arg_add(cmd, &arg, NULL);
if (ret)
return ret;
va_start(args, loc);
for (;;) {
const char *field;
field = va_arg(args, const char *);
if (!field)
break;
if (++cmd->n_fields > MAX_TRACE_ARGS) {
ret = -EINVAL;
break;
}
arg.str = field;
ret = dynevent_arg_add(cmd, &arg, NULL);
if (ret)
break;
}
va_end(args);
return ret;
}
EXPORT_SYMBOL_GPL(__kprobe_event_gen_cmd_start);
/**
* __kprobe_event_add_fields - Add probe fields to a kprobe command from arg list
* @cmd: A pointer to the dynevent_cmd struct representing the new event
* @...: Variable number of arg (pairs), one pair for each field
*
* NOTE: Users normally won't want to call this function directly, but
* rather use the kprobe_event_add_fields() wrapper, which
* automatically adds a NULL to the end of the arg list. If this
* function is used directly, make sure the last arg in the variable
* arg list is NULL.
*
* Add probe fields to an existing kprobe command using a variable
* list of args. Fields are added in the same order they're listed.
*
* Return: 0 if successful, error otherwise.
*/
int __kprobe_event_add_fields(struct dynevent_cmd *cmd, ...)
{
struct dynevent_arg arg;
va_list args;
int ret = 0;
if (cmd->type != DYNEVENT_TYPE_KPROBE)
return -EINVAL;
dynevent_arg_init(&arg, 0);
va_start(args, cmd);
for (;;) {
const char *field;
field = va_arg(args, const char *);
if (!field)
break;
if (++cmd->n_fields > MAX_TRACE_ARGS) {
ret = -EINVAL;
break;
}
arg.str = field;
ret = dynevent_arg_add(cmd, &arg, NULL);
if (ret)
break;
}
va_end(args);
return ret;
}
EXPORT_SYMBOL_GPL(__kprobe_event_add_fields);
/**
* kprobe_event_delete - Delete a kprobe event
* @name: The name of the kprobe event to delete
*
* Delete a kprobe event with the give @name from kernel code rather
* than directly from the command line.
*
* Return: 0 if successful, error otherwise.
*/
int kprobe_event_delete(const char *name)
{
char buf[MAX_EVENT_NAME_LEN];
snprintf(buf, MAX_EVENT_NAME_LEN, "-:%s", name);
return create_or_delete_trace_kprobe(buf);
}
EXPORT_SYMBOL_GPL(kprobe_event_delete);
static int trace_kprobe_release(struct dyn_event *ev)
{
struct trace_kprobe *tk = to_trace_kprobe(ev);
int ret = unregister_trace_kprobe(tk);
if (!ret)
free_trace_kprobe(tk);
return ret;
}
static int trace_kprobe_show(struct seq_file *m, struct dyn_event *ev)
{
struct trace_kprobe *tk = to_trace_kprobe(ev);
int i;
seq_putc(m, trace_kprobe_is_return(tk) ? 'r' : 'p');
if (trace_kprobe_is_return(tk) && tk->rp.maxactive)
seq_printf(m, "%d", tk->rp.maxactive);
seq_printf(m, ":%s/%s", trace_probe_group_name(&tk->tp),
trace_probe_name(&tk->tp));
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 int probes_seq_show(struct seq_file *m, void *v)
{
struct dyn_event *ev = v;
if (!is_trace_kprobe(ev))
return 0;
return trace_kprobe_show(m, ev);
}
static const struct seq_operations probes_seq_op = {
.start = dyn_event_seq_start,
.next = dyn_event_seq_next,
.stop = dyn_event_seq_stop,
.show = probes_seq_show
};
static int probes_open(struct inode *inode, struct file *file)
{
int ret;
ret = security_locked_down(LOCKDOWN_TRACEFS);
if (ret)
return ret;
if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
ret = dyn_events_release_all(&trace_kprobe_ops);
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 trace_parse_run_command(file, buffer, count, ppos,
create_or_delete_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,
};
static unsigned long trace_kprobe_missed(struct trace_kprobe *tk)
{
return trace_kprobe_is_return(tk) ?
tk->rp.kp.nmissed + tk->rp.nmissed : tk->rp.kp.nmissed;
}
/* Probes profiling interfaces */
static int probes_profile_seq_show(struct seq_file *m, void *v)
{
struct dyn_event *ev = v;
struct trace_kprobe *tk;
unsigned long nmissed;
if (!is_trace_kprobe(ev))
return 0;
tk = to_trace_kprobe(ev);
nmissed = trace_kprobe_missed(tk);
seq_printf(m, " %-44s %15lu %15lu\n",
trace_probe_name(&tk->tp),
trace_kprobe_nhit(tk),
nmissed);
return 0;
}
static const struct seq_operations profile_seq_op = {
.start = dyn_event_seq_start,
.next = dyn_event_seq_next,
.stop = dyn_event_seq_stop,
.show = probes_profile_seq_show
};
static int profile_open(struct inode *inode, struct file *file)
{
int ret;
ret = security_locked_down(LOCKDOWN_TRACEFS);
if (ret)
return ret;
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,
};
/* Note that we don't verify it, since the code does not come from user space */
static int
process_fetch_insn(struct fetch_insn *code, void *rec, void *edata,
void *dest, void *base)
{
struct pt_regs *regs = rec;
unsigned long val;
int ret;
retry:
/* 1st stage: get value from context */
switch (code->op) {
case FETCH_OP_REG:
val = regs_get_register(regs, code->param);
break;
case FETCH_OP_STACK:
val = regs_get_kernel_stack_nth(regs, code->param);
break;
case FETCH_OP_STACKP:
val = kernel_stack_pointer(regs);
break;
case FETCH_OP_RETVAL:
val = regs_return_value(regs);
break;
#ifdef CONFIG_HAVE_FUNCTION_ARG_ACCESS_API
case FETCH_OP_ARG:
val = regs_get_kernel_argument(regs, code->param);
break;
case FETCH_OP_EDATA:
val = *(unsigned long *)((unsigned long)edata + code->offset);
break;
#endif
case FETCH_NOP_SYMBOL: /* Ignore a place holder */
code++;
goto retry;
default:
ret = process_common_fetch_insn(code, &val);
if (ret < 0)
return ret;
}
code++;
return process_fetch_insn_bottom(code, val, dest, base);
}
NOKPROBE_SYMBOL(process_fetch_insn)
/* Kprobe handler */
static nokprobe_inline void
__kprobe_trace_func(struct trace_kprobe *tk, struct pt_regs *regs,
struct trace_event_file *trace_file)
{
struct kprobe_trace_entry_head *entry;
struct trace_event_call *call = trace_probe_event_call(&tk->tp);
struct trace_event_buffer fbuffer;
int dsize;
WARN_ON(call != trace_file->event_call);
if (trace_trigger_soft_disabled(trace_file))
return;
dsize = __get_data_size(&tk->tp, regs, NULL);
entry = trace_event_buffer_reserve(&fbuffer, trace_file,
sizeof(*entry) + tk->tp.size + dsize);
if (!entry)
return;
fbuffer.regs = regs;
entry->ip = (unsigned long)tk->rp.kp.addr;
store_trace_args(&entry[1], &tk->tp, regs, NULL, sizeof(*entry), dsize);
trace_event_buffer_commit(&fbuffer);
}
static void
kprobe_trace_func(struct trace_kprobe *tk, struct pt_regs *regs)
{
struct event_file_link *link;
trace_probe_for_each_link_rcu(link, &tk->tp)
__kprobe_trace_func(tk, regs, link->file);
}
NOKPROBE_SYMBOL(kprobe_trace_func);
/* Kretprobe handler */
static int trace_kprobe_entry_handler(struct kretprobe_instance *ri,
struct pt_regs *regs)
{
struct kretprobe *rp = get_kretprobe(ri);
struct trace_kprobe *tk;
/*
* There is a small chance that get_kretprobe(ri) returns NULL when
* the kretprobe is unregister on another CPU between kretprobe's
* trampoline_handler and this function.
*/
if (unlikely(!rp))
return -ENOENT;
tk = container_of(rp, struct trace_kprobe, rp);
/* store argument values into ri->data as entry data */
if (tk->tp.entry_arg)
store_trace_entry_data(ri->data, &tk->tp, regs);
return 0;
}
static nokprobe_inline void
__kretprobe_trace_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
struct pt_regs *regs,
struct trace_event_file *trace_file)
{
struct kretprobe_trace_entry_head *entry;
struct trace_event_buffer fbuffer;
struct trace_event_call *call = trace_probe_event_call(&tk->tp);
int dsize;
WARN_ON(call != trace_file->event_call);
if (trace_trigger_soft_disabled(trace_file))
return;
dsize = __get_data_size(&tk->tp, regs, ri->data);
entry = trace_event_buffer_reserve(&fbuffer, trace_file,
sizeof(*entry) + tk->tp.size + dsize);
if (!entry)
return;
fbuffer.regs = regs;
entry->func = (unsigned long)tk->rp.kp.addr;
entry->ret_ip = get_kretprobe_retaddr(ri);
store_trace_args(&entry[1], &tk->tp, regs, ri->data, sizeof(*entry), dsize);
trace_event_buffer_commit(&fbuffer);
}
static void
kretprobe_trace_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
struct pt_regs *regs)
{
struct event_file_link *link;
trace_probe_for_each_link_rcu(link, &tk->tp)
__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;
field = (struct kprobe_trace_entry_head *)iter->ent;
tp = trace_probe_primary_from_call(
container_of(event, struct trace_event_call, event));
if (WARN_ON_ONCE(!tp))
goto out;
trace_seq_printf(s, "%s: (", trace_probe_name(tp));
if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
goto out;
trace_seq_putc(s, ')');
if (trace_probe_print_args(s, tp->args, tp->nr_args,
(u8 *)&field[1], field) < 0)
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;
field = (struct kretprobe_trace_entry_head *)iter->ent;
tp = trace_probe_primary_from_call(
container_of(event, struct trace_event_call, event));
if (WARN_ON_ONCE(!tp))
goto out;
trace_seq_printf(s, "%s: (", trace_probe_name(tp));
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, ')');
if (trace_probe_print_args(s, tp->args, tp->nr_args,
(u8 *)&field[1], field) < 0)
goto out;
trace_seq_putc(s, '\n');
out:
return trace_handle_return(s);
}
static int kprobe_event_define_fields(struct trace_event_call *event_call)
{
int ret;
struct kprobe_trace_entry_head field;
struct trace_probe *tp;
tp = trace_probe_primary_from_call(event_call);
if (WARN_ON_ONCE(!tp))
return -ENOENT;
DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
return traceprobe_define_arg_fields(event_call, sizeof(field), tp);
}
static int kretprobe_event_define_fields(struct trace_event_call *event_call)
{
int ret;
struct kretprobe_trace_entry_head field;
struct trace_probe *tp;
tp = trace_probe_primary_from_call(event_call);
if (WARN_ON_ONCE(!tp))
return -ENOENT;
DEFINE_FIELD(unsigned long, func, FIELD_STRING_FUNC, 0);
DEFINE_FIELD(unsigned long, ret_ip, FIELD_STRING_RETIP, 0);
return traceprobe_define_arg_fields(event_call, sizeof(field), tp);
}
#ifdef CONFIG_PERF_EVENTS
/* Kprobe profile handler */
static int
kprobe_perf_func(struct trace_kprobe *tk, struct pt_regs *regs)
{
struct trace_event_call *call = trace_probe_event_call(&tk->tp);
struct kprobe_trace_entry_head *entry;
struct hlist_head *head;
int size, __size, dsize;
int rctx;
if (bpf_prog_array_valid(call)) {
unsigned long orig_ip = instruction_pointer(regs);
int ret;
ret = trace_call_bpf(call, regs);
/*
* We need to check and see if we modified the pc of the
* pt_regs, and if so return 1 so that we don't do the
* single stepping.
*/
if (orig_ip != instruction_pointer(regs))
return 1;
if (!ret)
return 0;
}
head = this_cpu_ptr(call->perf_events);
if (hlist_empty(head))
return 0;
dsize = __get_data_size(&tk->tp, regs, NULL);
__size = sizeof(*entry) + tk->tp.size + dsize;
size = ALIGN(__size + sizeof(u32), sizeof(u64));
size -= sizeof(u32);
entry = perf_trace_buf_alloc(size, NULL, &rctx);
if (!entry)
return 0;
entry->ip = (unsigned long)tk->rp.kp.addr;
memset(&entry[1], 0, dsize);
store_trace_args(&entry[1], &tk->tp, regs, NULL, sizeof(*entry), dsize);
perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
head, NULL);
return 0;
}
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 trace_event_call *call = trace_probe_event_call(&tk->tp);
struct kretprobe_trace_entry_head *entry;
struct hlist_head *head;
int size, __size, dsize;
int rctx;
if (bpf_prog_array_valid(call) && !trace_call_bpf(call, regs))
return;
head = this_cpu_ptr(call->perf_events);
if (hlist_empty(head))
return;
dsize = __get_data_size(&tk->tp, regs, ri->data);
__size = sizeof(*entry) + tk->tp.size + dsize;
size = ALIGN(__size + sizeof(u32), sizeof(u64));
size -= sizeof(u32);
entry = perf_trace_buf_alloc(size, NULL, &rctx);
if (!entry)
return;
entry->func = (unsigned long)tk->rp.kp.addr;
entry->ret_ip = get_kretprobe_retaddr(ri);
store_trace_args(&entry[1], &tk->tp, regs, ri->data, sizeof(*entry), dsize);
perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
head, NULL);
}
NOKPROBE_SYMBOL(kretprobe_perf_func);
int bpf_get_kprobe_info(const struct perf_event *event, u32 *fd_type,
const char **symbol, u64 *probe_offset,
u64 *probe_addr, unsigned long *missed,
bool perf_type_tracepoint)
{
const char *pevent = trace_event_name(event->tp_event);
const char *group = event->tp_event->class->system;
struct trace_kprobe *tk;
if (perf_type_tracepoint)
tk = find_trace_kprobe(pevent, group);
else
tk = trace_kprobe_primary_from_call(event->tp_event);
if (!tk)
return -EINVAL;
*fd_type = trace_kprobe_is_return(tk) ? BPF_FD_TYPE_KRETPROBE
: BPF_FD_TYPE_KPROBE;
*probe_offset = tk->rp.kp.offset;
*probe_addr = kallsyms_show_value(current_cred()) ?
(unsigned long)tk->rp.kp.addr : 0;
*symbol = tk->symbol;
if (missed)
*missed = trace_kprobe_missed(tk);
return 0;
}
#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 trace_event_call *event,
enum trace_reg type, void *data)
{
struct trace_event_file *file = data;
switch (type) {
case TRACE_REG_REGISTER:
return enable_trace_kprobe(event, file);
case TRACE_REG_UNREGISTER:
return disable_trace_kprobe(event, file);
#ifdef CONFIG_PERF_EVENTS
case TRACE_REG_PERF_REGISTER:
return enable_trace_kprobe(event, NULL);
case TRACE_REG_PERF_UNREGISTER:
return disable_trace_kprobe(event, 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);
int ret = 0;
raw_cpu_inc(*tk->nhit);
if (trace_probe_test_flag(&tk->tp, TP_FLAG_TRACE))
kprobe_trace_func(tk, regs);
#ifdef CONFIG_PERF_EVENTS
if (trace_probe_test_flag(&tk->tp, TP_FLAG_PROFILE))
ret = kprobe_perf_func(tk, regs);
#endif
return ret;
}
NOKPROBE_SYMBOL(kprobe_dispatcher);
static int
kretprobe_dispatcher(struct kretprobe_instance *ri, struct pt_regs *regs)
{
struct kretprobe *rp = get_kretprobe(ri);
struct trace_kprobe *tk;
/*
* There is a small chance that get_kretprobe(ri) returns NULL when
* the kretprobe is unregister on another CPU between kretprobe's
* trampoline_handler and this function.
*/
if (unlikely(!rp))
return 0;
tk = container_of(rp, struct trace_kprobe, rp);
raw_cpu_inc(*tk->nhit);
if (trace_probe_test_flag(&tk->tp, TP_FLAG_TRACE))
kretprobe_trace_func(tk, ri, regs);
#ifdef CONFIG_PERF_EVENTS
if (trace_probe_test_flag(&tk->tp, TP_FLAG_PROFILE))
kretprobe_perf_func(tk, ri, regs);
#endif
return 0; /* We don't tweak 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 struct trace_event_fields kretprobe_fields_array[] = {
{ .type = TRACE_FUNCTION_TYPE,
.define_fields = kretprobe_event_define_fields },
{}
};
static struct trace_event_fields kprobe_fields_array[] = {
{ .type = TRACE_FUNCTION_TYPE,
.define_fields = kprobe_event_define_fields },
{}
};
static inline void init_trace_event_call(struct trace_kprobe *tk)
{
struct trace_event_call *call = trace_probe_event_call(&tk->tp);
if (trace_kprobe_is_return(tk)) {
call->event.funcs = &kretprobe_funcs;
call->class->fields_array = kretprobe_fields_array;
} else {
call->event.funcs = &kprobe_funcs;
call->class->fields_array = kprobe_fields_array;
}
call->flags = TRACE_EVENT_FL_KPROBE;
call->class->reg = kprobe_register;
}
static int register_kprobe_event(struct trace_kprobe *tk)
{
init_trace_event_call(tk);
return trace_probe_register_event_call(&tk->tp);
}
static int unregister_kprobe_event(struct trace_kprobe *tk)
{
return trace_probe_unregister_event_call(&tk->tp);
}
#ifdef CONFIG_PERF_EVENTS
/* create a trace_kprobe, but don't add it to global lists */
struct trace_event_call *
create_local_trace_kprobe(char *func, void *addr, unsigned long offs,
bool is_return)
{
enum probe_print_type ptype;
struct trace_kprobe *tk;
int ret;
char *event;
if (func) {
unsigned int count;
count = number_of_same_symbols(func);
if (count > 1)
/*
* Users should use addr to remove the ambiguity of
* using func only.
*/
return ERR_PTR(-EADDRNOTAVAIL);
else if (count == 0)
/*
* We can return ENOENT earlier than when register the
* kprobe.
*/
return ERR_PTR(-ENOENT);
}
/*
* local trace_kprobes are not added to dyn_event, so they are never
* searched in find_trace_kprobe(). Therefore, there is no concern of
* duplicated name here.
*/
event = func ? func : "DUMMY_EVENT";
tk = alloc_trace_kprobe(KPROBE_EVENT_SYSTEM, event, (void *)addr, func,
offs, 0 /* maxactive */, 0 /* nargs */,
is_return);
if (IS_ERR(tk)) {
pr_info("Failed to allocate trace_probe.(%d)\n",
(int)PTR_ERR(tk));
return ERR_CAST(tk);
}
init_trace_event_call(tk);
ptype = trace_kprobe_is_return(tk) ?
PROBE_PRINT_RETURN : PROBE_PRINT_NORMAL;
if (traceprobe_set_print_fmt(&tk->tp, ptype) < 0) {
ret = -ENOMEM;
goto error;
}
ret = __register_trace_kprobe(tk);
if (ret < 0)
goto error;
return trace_probe_event_call(&tk->tp);
error:
free_trace_kprobe(tk);
return ERR_PTR(ret);
}
void destroy_local_trace_kprobe(struct trace_event_call *event_call)
{
struct trace_kprobe *tk;
tk = trace_kprobe_primary_from_call(event_call);
if (unlikely(!tk))
return;
if (trace_probe_is_enabled(&tk->tp)) {
WARN_ON(1);
return;
}
__unregister_trace_kprobe(tk);
free_trace_kprobe(tk);
}
#endif /* CONFIG_PERF_EVENTS */
static __init void enable_boot_kprobe_events(void)
{
struct trace_array *tr = top_trace_array();
struct trace_event_file *file;
struct trace_kprobe *tk;
struct dyn_event *pos;
mutex_lock(&event_mutex);
for_each_trace_kprobe(tk, pos) {
list_for_each_entry(file, &tr->events, list)
if (file->event_call == trace_probe_event_call(&tk->tp))
trace_event_enable_disable(file, 1, 0);
}
mutex_unlock(&event_mutex);
}
static __init void setup_boot_kprobe_events(void)
{
char *p, *cmd = kprobe_boot_events_buf;
int ret;
strreplace(kprobe_boot_events_buf, ',', ' ');
while (cmd && *cmd != '\0') {
p = strchr(cmd, ';');
if (p)
*p++ = '\0';
ret = create_or_delete_trace_kprobe(cmd);
if (ret)
pr_warn("Failed to add event(%d): %s\n", ret, cmd);
cmd = p;
}
enable_boot_kprobe_events();
}
/*
* Register dynevent at core_initcall. This allows kernel to setup kprobe
* events in postcore_initcall without tracefs.
*/
static __init int init_kprobe_trace_early(void)
{
int ret;
ret = dyn_event_register(&trace_kprobe_ops);
if (ret)
return ret;
if (register_module_notifier(&trace_kprobe_module_nb))
return -EINVAL;
return 0;
}
core_initcall(init_kprobe_trace_early);
/* Make a tracefs interface for controlling probe points */
static __init int init_kprobe_trace(void)
{
int ret;
ret = tracing_init_dentry();
if (ret)
return 0;
/* Event list interface */
trace_create_file("kprobe_events", TRACE_MODE_WRITE,
NULL, NULL, &kprobe_events_ops);
/* Profile interface */
trace_create_file("kprobe_profile", TRACE_MODE_READ,
NULL, NULL, &kprobe_profile_ops);
setup_boot_kprobe_events();
return 0;
}
fs_initcall(init_kprobe_trace);
#ifdef CONFIG_FTRACE_STARTUP_TEST
static __init struct trace_event_file *
find_trace_probe_file(struct trace_kprobe *tk, struct trace_array *tr)
{
struct trace_event_file *file;
list_for_each_entry(file, &tr->events, list)
if (file->event_call == trace_probe_event_call(&tk->tp))
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 trace_event_file *file;
if (tracing_is_disabled())
return -ENODEV;
if (tracing_selftest_disabled)
return 0;
target = kprobe_trace_selftest_target;
pr_info("Testing kprobe tracing: ");
ret = create_or_delete_trace_kprobe("p:testprobe kprobe_trace_selftest_target $stack $stack0 +0($stack)");
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(
trace_probe_event_call(&tk->tp), file);
}
}
ret = create_or_delete_trace_kprobe("r:testprobe2 kprobe_trace_selftest_target $retval");
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(
trace_probe_event_call(&tk->tp), file);
}
}
if (warn)
goto end;
ret = target(1, 2, 3, 4, 5, 6);
/*
* Not expecting an error here, the check is only to prevent the
* optimizer from removing the call to target() as otherwise there
* are no side-effects and the call is never performed.
*/
if (ret != 21)
warn++;
/* 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 {
if (trace_kprobe_nhit(tk) != 1) {
pr_warn("incorrect number of testprobe hits\n");
warn++;
}
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(
trace_probe_event_call(&tk->tp), 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 {
if (trace_kprobe_nhit(tk) != 1) {
pr_warn("incorrect number of testprobe2 hits\n");
warn++;
}
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(
trace_probe_event_call(&tk->tp), file);
}
ret = create_or_delete_trace_kprobe("-:testprobe");
if (WARN_ON_ONCE(ret)) {
pr_warn("error on deleting a probe.\n");
warn++;
}
ret = create_or_delete_trace_kprobe("-:testprobe2");
if (WARN_ON_ONCE(ret)) {
pr_warn("error on deleting a probe.\n");
warn++;
}
end:
ret = dyn_events_release_all(&trace_kprobe_ops);
if (WARN_ON_ONCE(ret)) {
pr_warn("error on cleaning up probes.\n");
warn++;
}
/*
* Wait for the optimizer work to finish. Otherwise it might fiddle
* with probes in already freed __init text.
*/
wait_for_kprobe_optimizer();
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