blob: 5265117ad7e8599e1bf9ff3ba3212b815012f939 [file] [log] [blame]
// 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/module.h>
#include <linux/uaccess.h>
#include <linux/rculist.h>
#include <linux/error-injection.h>
#include "trace_dynevent.h"
#include "trace_kprobe_selftest.h"
#include "trace_probe.h"
#include "trace_probe_tmpl.h"
#define KPROBE_EVENT_SYSTEM "kprobes"
#define KRETPROBE_MAXACTIVE_MAX 4096
static int trace_kprobe_create(int argc, const char **argv);
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,
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)))
#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_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';
mutex_lock(&module_mutex);
ret = !!find_module(tk->symbol);
mutex_unlock(&module_mutex);
*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(const char *system, const char *event,
struct dyn_event *ev)
{
struct trace_kprobe *tk = to_trace_kprobe(ev);
return strcmp(trace_event_name(&tk->tp.call), event) == 0 &&
(!system || strcmp(tk->tp.call.class->system, system) == 0);
}
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;
}
/* 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;
}
bool trace_kprobe_on_func_entry(struct trace_event_call *call)
{
struct trace_kprobe *tk = (struct trace_kprobe *)call->data;
return 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);
}
bool trace_kprobe_error_injectable(struct trace_event_call *call)
{
struct trace_kprobe *tk = (struct trace_kprobe *)call->data;
return within_error_injection_list(trace_kprobe_address(tk));
}
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);
/*
* 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(SIZEOF_TRACE_KPROBE(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;
if (!event || !group) {
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;
tk->tp.class.system = kstrdup(group, GFP_KERNEL);
if (!tk->tp.class.system)
goto error;
dyn_event_init(&tk->devent, &trace_kprobe_ops);
INIT_LIST_HEAD(&tk->tp.files);
return tk;
error:
kfree(tk->tp.call.name);
kfree(tk->symbol);
free_percpu(tk->nhit);
kfree(tk);
return ERR_PTR(ret);
}
static void free_trace_kprobe(struct trace_kprobe *tk)
{
int i;
if (!tk)
return;
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);
free_percpu(tk->nhit);
kfree(tk);
}
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_event_name(&tk->tp.call), event) == 0 &&
strcmp(tk->tp.call.class->system, group) == 0)
return tk;
return NULL;
}
static inline int __enable_trace_kprobe(struct trace_kprobe *tk)
{
int ret = 0;
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);
}
return ret;
}
/*
* 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 trace_event_file *file)
{
struct event_file_link *link;
int ret = 0;
if (file) {
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;
ret = __enable_trace_kprobe(tk);
if (ret) {
list_del_rcu(&link->list);
kfree(link);
tk->tp.flags &= ~TP_FLAG_TRACE;
}
} else {
tk->tp.flags |= TP_FLAG_PROFILE;
ret = __enable_trace_kprobe(tk);
if (ret)
tk->tp.flags &= ~TP_FLAG_PROFILE;
}
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 trace_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;
}
/*
* if tk is not added to any list, it must be a local trace_kprobe
* created with perf_event_open. We don't need to wait for these
* trace_kprobes
*/
if (list_empty(&tk->devent.list))
wait = 0;
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_rcu();
kfree(link); /* Ignored if link == NULL */
}
return ret;
}
#if defined(CONFIG_KPROBES_ON_FTRACE) && \
!defined(CONFIG_KPROBE_EVENTS_ON_NOTRACE)
static bool within_notrace_func(struct trace_kprobe *tk)
{
unsigned long offset, size, addr;
addr = trace_kprobe_address(tk);
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);
}
#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;
if (trace_probe_is_registered(&tk->tp))
return -EINVAL;
if (within_notrace_func(tk)) {
pr_warn("Could not probe notrace function %s\n",
trace_kprobe_symbol(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);
if (ret == 0) {
tk->tp.flags |= TP_FLAG_REGISTERED;
} else if (ret == -EILSEQ) {
pr_warn("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 */
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);
dyn_event_remove(&tk->devent);
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(&event_mutex);
/* Delete old (same name) event if exist */
old_tk = find_trace_kprobe(trace_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_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);
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_event_name(&tk->tp.call),
mod->name, 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 */
};
/* Convert certain expected symbols into '_' when generating event names */
static inline void sanitize_event_name(char *name)
{
while (*name++ != '\0')
if (*name == ':' || *name == '.')
*name = '_';
}
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]
* 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;
int i, len, ret = 0;
bool is_return = false;
char *symbol = NULL, *tmp = NULL;
const char *event = NULL, *group = KPROBE_EVENT_SYSTEM;
int maxactive = 0;
long offset = 0;
void *addr = NULL;
char buf[MAX_EVENT_NAME_LEN];
unsigned int flags = TPARG_FL_KERNEL;
switch (argv[0][0]) {
case 'r':
is_return = true;
flags |= TPARG_FL_RETURN;
break;
case 'p':
break;
default:
return -ECANCELED;
}
if (argc < 2)
return -ECANCELED;
event = strchr(&argv[0][1], ':');
if (event)
event++;
if (isdigit(argv[0][1])) {
if (!is_return) {
pr_info("Maxactive is not for kprobe");
return -EINVAL;
}
if (event)
len = event - &argv[0][1] - 1;
else
len = strlen(&argv[0][1]);
if (len > MAX_EVENT_NAME_LEN - 1)
return -E2BIG;
memcpy(buf, &argv[0][1], len);
buf[len] = '\0';
ret = kstrtouint(buf, 0, &maxactive);
if (ret || !maxactive) {
pr_info("Invalid maxactive number\n");
return ret;
}
/* kretprobes instances are iterated over via a list. The
* maximum should stay reasonable.
*/
if (maxactive > KRETPROBE_MAXACTIVE_MAX) {
pr_info("Maxactive is too big (%d > %d).\n",
maxactive, KRETPROBE_MAXACTIVE_MAX);
return -E2BIG;
}
}
/* try to parse an address. if that fails, try to read the
* input as a symbol. */
if (kstrtoul(argv[1], 0, (unsigned long *)&addr)) {
/* Check whether uprobe event specified */
if (strchr(argv[1], '/') && strchr(argv[1], ':'))
return -ECANCELED;
/* a symbol specified */
symbol = kstrdup(argv[1], GFP_KERNEL);
if (!symbol)
return -ENOMEM;
/* TODO: support .init module functions */
ret = traceprobe_split_symbol_offset(symbol, &offset);
if (ret || offset < 0 || offset > UINT_MAX) {
pr_info("Failed to parse either an address or a symbol.\n");
goto out;
}
if (kprobe_on_func_entry(NULL, symbol, offset))
flags |= TPARG_FL_FENTRY;
if (offset && is_return && !(flags & TPARG_FL_FENTRY)) {
pr_info("Given offset is not valid for return probe.\n");
ret = -EINVAL;
goto out;
}
}
argc -= 2; argv += 2;
if (event) {
ret = traceprobe_parse_event_name(&event, &group, buf);
if (ret)
goto out;
} else {
/* 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;
}
/* setup a probe */
tk = alloc_trace_kprobe(group, event, addr, symbol, offset, maxactive,
argc, is_return);
if (IS_ERR(tk)) {
pr_info("Failed to allocate trace_probe.(%d)\n",
(int)PTR_ERR(tk));
ret = PTR_ERR(tk);
goto out;
}
/* parse arguments */
for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
tmp = kstrdup(argv[i], GFP_KERNEL);
if (!tmp) {
ret = -ENOMEM;
goto error;
}
ret = traceprobe_parse_probe_arg(&tk->tp, i, tmp, flags);
kfree(tmp);
if (ret)
goto error;
}
ret = register_trace_kprobe(tk);
if (ret)
goto error;
out:
kfree(symbol);
return ret;
error:
free_trace_kprobe(tk);
goto out;
}
static int create_or_delete_trace_kprobe(int argc, char **argv)
{
int ret;
if (argv[0][0] == '-')
return dyn_event_release(argc, argv, &trace_kprobe_ops);
ret = trace_kprobe_create(argc, (const char **)argv);
return ret == -ECANCELED ? -EINVAL : ret;
}
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');
seq_printf(m, ":%s/%s", tk->tp.call.class->system,
trace_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 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;
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,
};
/* Probes profiling interfaces */
static int probes_profile_seq_show(struct seq_file *m, void *v)
{
struct dyn_event *ev = v;
struct trace_kprobe *tk;
if (!is_trace_kprobe(ev))
return 0;
tk = to_trace_kprobe(ev);
seq_printf(m, " %-44s %15lu %15lu\n",
trace_event_name(&tk->tp.call),
trace_kprobe_nhit(tk),
tk->rp.kp.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)
{
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 specific fetch functions */
/* Return the length of string -- including null terminal byte */
static nokprobe_inline int
fetch_store_strlen(unsigned long addr)
{
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);
return (ret < 0) ? ret : len;
}
/*
* Fetch a null-terminated string. Caller MUST set *(u32 *)buf with max
* length and relative data location.
*/
static nokprobe_inline int
fetch_store_string(unsigned long addr, void *dest, void *base)
{
int maxlen = get_loc_len(*(u32 *)dest);
u8 *dst = get_loc_data(dest, base);
long ret;
if (unlikely(!maxlen))
return -ENOMEM;
/*
* Try to get string again, since the string can be changed while
* probing.
*/
ret = strncpy_from_unsafe(dst, (void *)addr, maxlen);
if (ret >= 0)
*(u32 *)dest = make_data_loc(ret, (void *)dst - base);
return ret;
}
static nokprobe_inline int
probe_mem_read(void *dest, void *src, size_t size)
{
return probe_kernel_read(dest, src, size);
}
/* 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, struct pt_regs *regs, void *dest,
void *base)
{
unsigned long val;
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;
case FETCH_OP_IMM:
val = code->immediate;
break;
case FETCH_OP_COMM:
val = (unsigned long)current->comm;
break;
#ifdef CONFIG_HAVE_FUNCTION_ARG_ACCESS_API
case FETCH_OP_ARG:
val = regs_get_kernel_argument(regs, code->param);
break;
#endif
case FETCH_NOP_SYMBOL: /* Ignore a place holder */
code++;
goto retry;
default:
return -EILSEQ;
}
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 ring_buffer_event *event;
struct ring_buffer *buffer;
int size, dsize, pc;
unsigned long irq_flags;
struct trace_event_call *call = &tk->tp.call;
WARN_ON(call != trace_file->event_call);
if (trace_trigger_soft_disabled(trace_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, trace_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(&entry[1], &tk->tp, regs, sizeof(*entry), dsize);
event_trigger_unlock_commit_regs(trace_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 trace_event_file *trace_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 trace_event_call *call = &tk->tp.call;
WARN_ON(call != trace_file->event_call);
if (trace_trigger_soft_disabled(trace_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, trace_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(&entry[1], &tk->tp, regs, sizeof(*entry), dsize);
event_trigger_unlock_commit_regs(trace_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;
field = (struct kprobe_trace_entry_head *)iter->ent;
tp = container_of(event, struct trace_probe, call.event);
trace_seq_printf(s, "%s: (", trace_event_name(&tp->call));
if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
goto out;
trace_seq_putc(s, ')');
if (print_probe_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 = container_of(event, struct trace_probe, call.event);
trace_seq_printf(s, "%s: (", trace_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, ')');
if (print_probe_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_kprobe *tk = (struct trace_kprobe *)event_call->data;
DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
return traceprobe_define_arg_fields(event_call, sizeof(field), &tk->tp);
}
static int kretprobe_event_define_fields(struct trace_event_call *event_call)
{
int ret;
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);
return traceprobe_define_arg_fields(event_call, sizeof(field), &tk->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 = &tk->tp.call;
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);
__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, 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 = &tk->tp.call;
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);
__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 = (unsigned long)ri->ret_addr;
store_trace_args(&entry[1], &tk->tp, regs, 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, 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 = event->tp_event->data;
if (!tk)
return -EINVAL;
*fd_type = trace_kprobe_is_return(tk) ? BPF_FD_TYPE_KRETPROBE
: BPF_FD_TYPE_KPROBE;
if (tk->symbol) {
*symbol = tk->symbol;
*probe_offset = tk->rp.kp.offset;
*probe_addr = 0;
} else {
*symbol = NULL;
*probe_offset = 0;
*probe_addr = (unsigned long)tk->rp.kp.addr;
}
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_kprobe *tk = (struct trace_kprobe *)event->data;
struct trace_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);
int ret = 0;
raw_cpu_inc(*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)
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 trace_kprobe *tk = container_of(ri->rp, struct trace_kprobe, rp);
raw_cpu_inc(*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 inline void init_trace_event_call(struct trace_kprobe *tk,
struct trace_event_call *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;
}
call->flags = TRACE_EVENT_FL_KPROBE;
call->class->reg = kprobe_register;
call->data = tk;
}
static int register_kprobe_event(struct trace_kprobe *tk)
{
struct trace_event_call *call = &tk->tp.call;
int ret = 0;
init_trace_event_call(tk, call);
if (traceprobe_set_print_fmt(&tk->tp, trace_kprobe_is_return(tk)) < 0)
return -ENOMEM;
ret = register_trace_event(&call->event);
if (!ret) {
kfree(call->print_fmt);
return -ENODEV;
}
ret = trace_add_event_call(call);
if (ret) {
pr_info("Failed to register kprobe event: %s\n",
trace_event_name(call));
kfree(call->print_fmt);
unregister_trace_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;
}
#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)
{
struct trace_kprobe *tk;
int ret;
char *event;
/*
* 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, &tk->tp.call);
if (traceprobe_set_print_fmt(&tk->tp, trace_kprobe_is_return(tk)) < 0) {
ret = -ENOMEM;
goto error;
}
ret = __register_trace_kprobe(tk);
if (ret < 0) {
kfree(tk->tp.call.print_fmt);
goto error;
}
return &tk->tp.call;
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 = container_of(event_call, struct trace_kprobe, tp.call);
if (trace_probe_is_enabled(&tk->tp)) {
WARN_ON(1);
return;
}
__unregister_trace_kprobe(tk);
kfree(tk->tp.call.print_fmt);
free_trace_kprobe(tk);
}
#endif /* CONFIG_PERF_EVENTS */
/* Make a tracefs interface for controlling probe points */
static __init int init_kprobe_trace(void)
{
struct dentry *d_tracer;
struct dentry *entry;
int ret;
ret = dyn_event_register(&trace_kprobe_ops);
if (ret)
return ret;
if (register_module_notifier(&trace_kprobe_module_nb))
return -EINVAL;
d_tracer = tracing_init_dentry();
if (IS_ERR(d_tracer))
return 0;
entry = tracefs_create_file("kprobe_events", 0644, d_tracer,
NULL, &kprobe_events_ops);
/* Event list interface */
if (!entry)
pr_warn("Could not create tracefs 'kprobe_events' entry\n");
/* Profile interface */
entry = tracefs_create_file("kprobe_profile", 0444, d_tracer,
NULL, &kprobe_profile_ops);
if (!entry)
pr_warn("Could not create tracefs 'kprobe_profile' entry\n");
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 == &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 trace_event_file *file;
if (tracing_is_disabled())
return -ENODEV;
target = kprobe_trace_selftest_target;
pr_info("Testing kprobe tracing: ");
ret = trace_run_command("p:testprobe kprobe_trace_selftest_target $stack $stack0 +0($stack)",
create_or_delete_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 = trace_run_command("r:testprobe2 kprobe_trace_selftest_target $retval",
create_or_delete_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);
/*
* 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(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 {
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(tk, file);
}
ret = trace_run_command("-:testprobe", create_or_delete_trace_kprobe);
if (WARN_ON_ONCE(ret)) {
pr_warn("error on deleting a probe.\n");
warn++;
}
ret = trace_run_command("-:testprobe2", create_or_delete_trace_kprobe);
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