/*
 * 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
 */
#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_probe.h"

#define KPROBE_EVENT_SYSTEM "kprobes"
#define KRETPROBE_MAXACTIVE_MAX 4096

/**
 * Kprobe event core functions
 */
struct trace_kprobe {
        struct list_head        list;
        struct kretprobe        rp;     /* Use rp.kp for kprobe use */
        unsigned long __percpu *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 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;
}

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;
        unsigned long addr;

        if (tk->symbol) {
                addr = (unsigned long)
                        kallsyms_lookup_name(trace_kprobe_symbol(tk));
                addr += tk->rp.kp.offset;
        } else {
                addr = (unsigned long)tk->rp.kp.addr;
        }
        return within_error_injection_list(addr);
}

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)
{
        int maxlen = get_rloc_len(*(u32 *)dest);
        u8 *dst = get_rloc_data(dest);
        long ret;

        if (!maxlen)
                return;

        /*
         * Try to get string again, since the string can be changed while
         * probing.
         */
        ret = strncpy_from_unsafe(dst, addr, maxlen);

        if (ret < 0) {  /* Failed to fetch string */
                dst[0] = '\0';
                *(u32 *)dest = make_data_rloc(0, get_rloc_offs(*(u32 *)dest));
        } else {
                *(u32 *)dest = make_data_rloc(ret, 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 */
static 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_ALIAS(x8,  u8,  u8,  0),
        ASSIGN_FETCH_TYPE_ALIAS(x16, u16, u16, 0),
        ASSIGN_FETCH_TYPE_ALIAS(x32, u32, u32, 0),
        ASSIGN_FETCH_TYPE_ALIAS(x64, u64, u64, 0),

        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 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 || !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);
        free_percpu(tk->nhit);
        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);
        free_percpu(tk->nhit);
        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(trace_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 trace_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 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->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_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 {
                if (ret == -ENOENT && trace_kprobe_is_on_module(tk)) {
                        pr_warn("This probe might be able to register after target module is loaded. Continue.\n");
                        ret = 0;
                } 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: 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(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 < 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_warn("Failed to re-register probe %s on %s: %d\n",
                                        trace_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 */
};

/* 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 create_trace_kprobe(int argc, 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, ret = 0;
        bool is_return = false, is_delete = false;
        char *symbol = NULL, *event = NULL, *group = NULL;
        int maxactive = 0;
        char *arg;
        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;
        }

        event = strchr(&argv[0][1], ':');
        if (event) {
                event[0] = '\0';
                event++;
        }
        if (is_return && isdigit(argv[0][1])) {
                ret = kstrtouint(&argv[0][1], 0, &maxactive);
                if (ret) {
                        pr_info("Failed to parse maxactive.\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;
                }
        }

        if (event) {
                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;
        }

        /* try to parse an address. if that fails, try to read the
         * input as a symbol. */
        if (kstrtoul(argv[1], 0, (unsigned long *)&addr)) {
                /* a symbol specified */
                symbol = argv[1];
                /* 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");
                        return ret;
                }
                if (offset && is_return &&
                    !kprobe_on_func_entry(NULL, symbol, offset)) {
                        pr_info("Given offset is not valid for return probe.\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);
                sanitize_event_name(buf);
                event = buf;
        }
        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));
                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,
                                                kprobes_fetch_type_table);
                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,
                        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 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 trace_parse_run_command(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",
                   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  = 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 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(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], 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(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], 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;
        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: (", trace_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: (", 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, ')');

        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 trace_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 trace_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 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 clear the kprobe and return 1 so that we
                 * don't do the single stepping.
                 * The ftrace kprobe handler leaves it up to us to re-enable
                 * preemption here before returning if we've modified the ip.
                 */
                if (orig_ip != instruction_pointer(regs)) {
                        reset_current_kprobe();
                        preempt_enable_no_resched();
                        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(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], 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(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], dsize);
        perf_trace_buf_submit(entry, size, rctx, call->event.type, 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 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 (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 probe_list, 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 (set_print_fmt(&tk->tp, trace_kprobe_is_return(tk)) < 0) {
                ret = -ENOMEM;
                goto error;
        }

        ret = __register_trace_kprobe(tk);
        if (ret < 0)
                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);
        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;

        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
/*
 * The "__used" keeps gcc from removing the function symbol
 * from the kallsyms table. 'noinline' makes sure that there
 * isn't an inlined version used by the test method below
 */
static __used __init noinline 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 __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_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_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_trace_kprobe);
        if (WARN_ON_ONCE(ret)) {
                pr_warn("error on deleting a probe.\n");
                warn++;
        }

        ret = trace_run_command("-:testprobe2", create_trace_kprobe);
        if (WARN_ON_ONCE(ret)) {
                pr_warn("error on deleting a probe.\n");
                warn++;
        }

end:
        release_all_trace_kprobes();
        /*
         * 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