Merge branch 'firewire-kernel-streaming' of git://git.alsa-project.org/alsa-kprivate

[firewire-audio.git] / kernel / trace / trace_kprobe.c

/*
 * Kprobes-based tracing events
 *
 * Created by Masami Hiramatsu <mhiramat@redhat.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <linux/module.h>
#include <linux/uaccess.h>
#include <linux/kprobes.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/smp.h>
#include <linux/debugfs.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/ptrace.h>
#include <linux/perf_event.h>
#include <linux/stringify.h>
#include <linux/limits.h>
#include <asm/bitsperlong.h>

#include "trace.h"
#include "trace_output.h"

#define MAX_TRACE_ARGS 128
#define MAX_ARGSTR_LEN 63
#define MAX_EVENT_NAME_LEN 64
#define MAX_STRING_SIZE PATH_MAX
#define KPROBE_EVENT_SYSTEM "kprobes"

/* Reserved field names */
#define FIELD_STRING_IP "__probe_ip"
#define FIELD_STRING_RETIP "__probe_ret_ip"
#define FIELD_STRING_FUNC "__probe_func"

const char *reserved_field_names[] = {
        "common_type",
        "common_flags",
        "common_preempt_count",
        "common_pid",
        "common_tgid",
        "common_lock_depth",
        FIELD_STRING_IP,
        FIELD_STRING_RETIP,
        FIELD_STRING_FUNC,
};

/* Printing function type */
typedef int (*print_type_func_t)(struct trace_seq *, const char *, void *,
                                 void *);
#define PRINT_TYPE_FUNC_NAME(type)      print_type_##type
#define PRINT_TYPE_FMT_NAME(type)       print_type_format_##type

/* Printing  in basic type function template */
#define DEFINE_BASIC_PRINT_TYPE_FUNC(type, fmt, cast)                   \
static __kprobes int PRINT_TYPE_FUNC_NAME(type)(struct trace_seq *s,    \
                                                const char *name,       \
                                                void *data, void *ent)\
{                                                                       \
        return trace_seq_printf(s, " %s=" fmt, name, (cast)*(type *)data);\
}                                                                       \
static const char PRINT_TYPE_FMT_NAME(type)[] = fmt;

DEFINE_BASIC_PRINT_TYPE_FUNC(u8, "%x", unsigned int)
DEFINE_BASIC_PRINT_TYPE_FUNC(u16, "%x", unsigned int)
DEFINE_BASIC_PRINT_TYPE_FUNC(u32, "%lx", unsigned long)
DEFINE_BASIC_PRINT_TYPE_FUNC(u64, "%llx", unsigned long long)
DEFINE_BASIC_PRINT_TYPE_FUNC(s8, "%d", int)
DEFINE_BASIC_PRINT_TYPE_FUNC(s16, "%d", int)
DEFINE_BASIC_PRINT_TYPE_FUNC(s32, "%ld", long)
DEFINE_BASIC_PRINT_TYPE_FUNC(s64, "%lld", long long)

/* data_rloc: data relative location, compatible with u32 */
#define make_data_rloc(len, roffs)      \
        (((u32)(len) << 16) | ((u32)(roffs) & 0xffff))
#define get_rloc_len(dl)        ((u32)(dl) >> 16)
#define get_rloc_offs(dl)       ((u32)(dl) & 0xffff)

static inline void *get_rloc_data(u32 *dl)
{
        return (u8 *)dl + get_rloc_offs(*dl);
}

/* For data_loc conversion */
static inline void *get_loc_data(u32 *dl, void *ent)
{
        return (u8 *)ent + get_rloc_offs(*dl);
}

/*
 * Convert data_rloc to data_loc:
 *  data_rloc stores the offset from data_rloc itself, but data_loc
 *  stores the offset from event entry.
 */
#define convert_rloc_to_loc(dl, offs)   ((u32)(dl) + (offs))

/* For defining macros, define string/string_size types */
typedef u32 string;
typedef u32 string_size;

/* Print type function for string type */
static __kprobes int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq *s,
                                                  const char *name,
                                                  void *data, void *ent)
{
        int len = *(u32 *)data >> 16;

        if (!len)
                return trace_seq_printf(s, " %s=(fault)", name);
        else
                return trace_seq_printf(s, " %s=\"%s\"", name,
                                        (const char *)get_loc_data(data, ent));
}
static const char PRINT_TYPE_FMT_NAME(string)[] = "\\\"%s\\\"";

/* Data fetch function type */
typedef void (*fetch_func_t)(struct pt_regs *, void *, void *);

struct fetch_param {
        fetch_func_t    fn;
        void *data;
};

static __kprobes void call_fetch(struct fetch_param *fprm,
                                 struct pt_regs *regs, void *dest)
{
        return fprm->fn(regs, fprm->data, dest);
}

#define FETCH_FUNC_NAME(method, type)   fetch_##method##_##type
/*
 * Define macro for basic types - we don't need to define s* types, because
 * we have to care only about bitwidth at recording time.
 */
#define DEFINE_BASIC_FETCH_FUNCS(method) \
DEFINE_FETCH_##method(u8)               \
DEFINE_FETCH_##method(u16)              \
DEFINE_FETCH_##method(u32)              \
DEFINE_FETCH_##method(u64)

#define CHECK_FETCH_FUNCS(method, fn)                   \
        (((FETCH_FUNC_NAME(method, u8) == fn) ||        \
          (FETCH_FUNC_NAME(method, u16) == fn) ||       \
          (FETCH_FUNC_NAME(method, u32) == fn) ||       \
          (FETCH_FUNC_NAME(method, u64) == fn) ||       \
          (FETCH_FUNC_NAME(method, string) == fn) ||    \
          (FETCH_FUNC_NAME(method, string_size) == fn)) \
         && (fn != NULL))

/* Data fetch function templates */
#define DEFINE_FETCH_reg(type)                                          \
static __kprobes void FETCH_FUNC_NAME(reg, type)(struct pt_regs *regs,  \
                                        void *offset, void *dest)       \
{                                                                       \
        *(type *)dest = (type)regs_get_register(regs,                   \
                                (unsigned int)((unsigned long)offset)); \
}
DEFINE_BASIC_FETCH_FUNCS(reg)
/* No string on the register */
#define fetch_reg_string NULL
#define fetch_reg_string_size NULL

#define DEFINE_FETCH_stack(type)                                        \
static __kprobes 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)); \
}
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_retval(type)                                       \
static __kprobes void FETCH_FUNC_NAME(retval, type)(struct pt_regs *regs,\
                                          void *dummy, void *dest)      \
{                                                                       \
        *(type *)dest = (type)regs_return_value(regs);                  \
}
DEFINE_BASIC_FETCH_FUNCS(retval)
/* No string on the retval */
#define fetch_retval_string NULL
#define fetch_retval_string_size NULL

#define DEFINE_FETCH_memory(type)                                       \
static __kprobes 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;                                 \
}
DEFINE_BASIC_FETCH_FUNCS(memory)
/*
 * Fetch a null-terminated string. Caller MUST set *(u32 *)dest with max
 * length and relative data location.
 */
static __kprobes void FETCH_FUNC_NAME(memory, string)(struct pt_regs *regs,
                                                      void *addr, void *dest)
{
        long ret;
        int maxlen = get_rloc_len(*(u32 *)dest);
        u8 *dst = get_rloc_data(dest);
        u8 *src = addr;
        mm_segment_t old_fs = get_fs();
        if (!maxlen)
                return;
        /*
         * Try to get string again, since the string can be changed while
         * probing.
         */
        set_fs(KERNEL_DS);
        pagefault_disable();
        do
                ret = __copy_from_user_inatomic(dst++, src++, 1);
        while (dst[-1] && ret == 0 && src - (u8 *)addr < maxlen);
        dst[-1] = '\0';
        pagefault_enable();
        set_fs(old_fs);

        if (ret < 0) {  /* Failed to fetch string */
                ((u8 *)get_rloc_data(dest))[0] = '\0';
                *(u32 *)dest = make_data_rloc(0, get_rloc_offs(*(u32 *)dest));
        } else
                *(u32 *)dest = make_data_rloc(src - (u8 *)addr,
                                              get_rloc_offs(*(u32 *)dest));
}
/* Return the length of string -- including null terminal byte */
static __kprobes void FETCH_FUNC_NAME(memory, string_size)(struct pt_regs *regs,
                                                        void *addr, void *dest)
{
        int ret, len = 0;
        u8 c;
        mm_segment_t 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;
}

/* Memory fetching by symbol */
struct symbol_cache {
        char *symbol;
        long offset;
        unsigned long addr;
};

static 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;
}

static void free_symbol_cache(struct symbol_cache *sc)
{
        kfree(sc->symbol);
        kfree(sc);
}

static 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;
}

#define DEFINE_FETCH_symbol(type)                                       \
static __kprobes 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;                                      \
}
DEFINE_BASIC_FETCH_FUNCS(symbol)
DEFINE_FETCH_symbol(string)
DEFINE_FETCH_symbol(string_size)

/* Dereference memory access function */
struct deref_fetch_param {
        struct fetch_param orig;
        long offset;
};

#define DEFINE_FETCH_deref(type)                                        \
static __kprobes void FETCH_FUNC_NAME(deref, type)(struct pt_regs *regs,\
                                            void *data, void *dest)     \
{                                                                       \
        struct deref_fetch_param *dprm = data;                          \
        unsigned long addr;                                             \
        call_fetch(&dprm->orig, regs, &addr);                           \
        if (addr) {                                                     \
                addr += dprm->offset;                                   \
                fetch_memory_##type(regs, (void *)addr, dest);          \
        } else                                                          \
                *(type *)dest = 0;                                      \
}
DEFINE_BASIC_FETCH_FUNCS(deref)
DEFINE_FETCH_deref(string)
DEFINE_FETCH_deref(string_size)

static __kprobes void free_deref_fetch_param(struct deref_fetch_param *data)
{
        if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
                free_deref_fetch_param(data->orig.data);
        else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
                free_symbol_cache(data->orig.data);
        kfree(data);
}

/* Default (unsigned long) fetch type */
#define __DEFAULT_FETCH_TYPE(t) u##t
#define _DEFAULT_FETCH_TYPE(t) __DEFAULT_FETCH_TYPE(t)
#define DEFAULT_FETCH_TYPE _DEFAULT_FETCH_TYPE(BITS_PER_LONG)
#define DEFAULT_FETCH_TYPE_STR __stringify(DEFAULT_FETCH_TYPE)

/* Fetch types */
enum {
        FETCH_MTD_reg = 0,
        FETCH_MTD_stack,
        FETCH_MTD_retval,
        FETCH_MTD_memory,
        FETCH_MTD_symbol,
        FETCH_MTD_deref,
        FETCH_MTD_END,
};

#define ASSIGN_FETCH_FUNC(method, type) \
        [FETCH_MTD_##method] = FETCH_FUNC_NAME(method, type)

#define __ASSIGN_FETCH_TYPE(_name, ptype, ftype, _size, sign, _fmttype) \
        {.name = _name,                         \
         .size = _size,                                 \
         .is_signed = sign,                             \
         .print = PRINT_TYPE_FUNC_NAME(ptype),          \
         .fmt = PRINT_TYPE_FMT_NAME(ptype),             \
         .fmttype = _fmttype,                           \
         .fetch = {                                     \
ASSIGN_FETCH_FUNC(reg, ftype),                          \
ASSIGN_FETCH_FUNC(stack, ftype),                        \
ASSIGN_FETCH_FUNC(retval, ftype),                       \
ASSIGN_FETCH_FUNC(memory, ftype),                       \
ASSIGN_FETCH_FUNC(symbol, ftype),                       \
ASSIGN_FETCH_FUNC(deref, ftype),                        \
          }                                             \
        }

#define ASSIGN_FETCH_TYPE(ptype, ftype, sign)                   \
        __ASSIGN_FETCH_TYPE(#ptype, ptype, ftype, sizeof(ftype), sign, #ptype)

#define FETCH_TYPE_STRING 0
#define FETCH_TYPE_STRSIZE 1

/* Fetch type information table */
static const struct fetch_type {
        const char      *name;          /* Name of type */
        size_t          size;           /* Byte size of type */
        int             is_signed;      /* Signed flag */
        print_type_func_t       print;  /* Print functions */
        const char      *fmt;           /* Fromat string */
        const char      *fmttype;       /* Name in format file */
        /* Fetch functions */
        fetch_func_t    fetch[FETCH_MTD_END];
} 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),
};

static const struct fetch_type *find_fetch_type(const char *type)
{
        int i;

        if (!type)
                type = DEFAULT_FETCH_TYPE_STR;

        for (i = 0; i < ARRAY_SIZE(fetch_type_table); i++)
                if (strcmp(type, fetch_type_table[i].name) == 0)
                        return &fetch_type_table[i];
        return NULL;
}

/* Special function : only accept unsigned long */
static __kprobes void fetch_stack_address(struct pt_regs *regs,
                                          void *dummy, void *dest)
{
        *(unsigned long *)dest = kernel_stack_pointer(regs);
}

static fetch_func_t get_fetch_size_function(const struct fetch_type *type,
                                            fetch_func_t orig_fn)
{
        int i;

        if (type != &fetch_type_table[FETCH_TYPE_STRING])
                return NULL;    /* Only string type needs size function */
        for (i = 0; i < FETCH_MTD_END; i++)
                if (type->fetch[i] == orig_fn)
                        return fetch_type_table[FETCH_TYPE_STRSIZE].fetch[i];

        WARN_ON(1);     /* This should not happen */
        return NULL;
}

/**
 * Kprobe event core functions
 */

struct probe_arg {
        struct fetch_param      fetch;
        struct fetch_param      fetch_size;
        unsigned int            offset; /* Offset from argument entry */
        const char              *name;  /* Name of this argument */
        const char              *comm;  /* Command of this argument */
        const struct fetch_type *type;  /* Type of this argument */
};

/* Flags for trace_probe */
#define TP_FLAG_TRACE   1
#define TP_FLAG_PROFILE 2

struct trace_probe {
        struct list_head        list;
        struct kretprobe        rp;     /* Use rp.kp for kprobe use */
        unsigned long           nhit;
        unsigned int            flags;  /* For TP_FLAG_* */
        const char              *symbol;        /* symbol name */
        struct ftrace_event_class       class;
        struct ftrace_event_call        call;
        ssize_t                 size;           /* trace entry size */
        unsigned int            nr_args;
        struct probe_arg        args[];
};

#define SIZEOF_TRACE_PROBE(n)                   \
        (offsetof(struct trace_probe, args) +   \
        (sizeof(struct probe_arg) * (n)))


static __kprobes int probe_is_return(struct trace_probe *tp)
{
        return tp->rp.handler != NULL;
}

static __kprobes const char *probe_symbol(struct trace_probe *tp)
{
        return tp->symbol ? tp->symbol : "unknown";
}

static int register_probe_event(struct trace_probe *tp);
static void unregister_probe_event(struct trace_probe *tp);

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);

/* Check the name is good for event/group/fields */
static int is_good_name(const char *name)
{
        if (!isalpha(*name) && *name != '_')
                return 0;
        while (*++name != '\0') {
                if (!isalpha(*name) && !isdigit(*name) && *name != '_')
                        return 0;
        }
        return 1;
}

/*
 * Allocate new trace_probe and initialize it (including kprobes).
 */
static struct trace_probe *alloc_trace_probe(const char *group,
                                             const char *event,
                                             void *addr,
                                             const char *symbol,
                                             unsigned long offs,
                                             int nargs, int is_return)
{
        struct trace_probe *tp;
        int ret = -ENOMEM;

        tp = kzalloc(SIZEOF_TRACE_PROBE(nargs), GFP_KERNEL);
        if (!tp)
                return ERR_PTR(ret);

        if (symbol) {
                tp->symbol = kstrdup(symbol, GFP_KERNEL);
                if (!tp->symbol)
                        goto error;
                tp->rp.kp.symbol_name = tp->symbol;
                tp->rp.kp.offset = offs;
        } else
                tp->rp.kp.addr = addr;

        if (is_return)
                tp->rp.handler = kretprobe_dispatcher;
        else
                tp->rp.kp.pre_handler = kprobe_dispatcher;

        if (!event || !is_good_name(event)) {
                ret = -EINVAL;
                goto error;
        }

        tp->call.class = &tp->class;
        tp->call.name = kstrdup(event, GFP_KERNEL);
        if (!tp->call.name)
                goto error;

        if (!group || !is_good_name(group)) {
                ret = -EINVAL;
                goto error;
        }

        tp->class.system = kstrdup(group, GFP_KERNEL);
        if (!tp->class.system)
                goto error;

        INIT_LIST_HEAD(&tp->list);
        return tp;
error:
        kfree(tp->call.name);
        kfree(tp->symbol);
        kfree(tp);
        return ERR_PTR(ret);
}

static void free_probe_arg(struct probe_arg *arg)
{
        if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))
                free_deref_fetch_param(arg->fetch.data);
        else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))
                free_symbol_cache(arg->fetch.data);
        kfree(arg->name);
        kfree(arg->comm);
}

static void free_trace_probe(struct trace_probe *tp)
{
        int i;

        for (i = 0; i < tp->nr_args; i++)
                free_probe_arg(&tp->args[i]);

        kfree(tp->call.class->system);
        kfree(tp->call.name);
        kfree(tp->symbol);
        kfree(tp);
}

static struct trace_probe *find_probe_event(const char *event,
                                            const char *group)
{
        struct trace_probe *tp;

        list_for_each_entry(tp, &probe_list, list)
                if (strcmp(tp->call.name, event) == 0 &&
                    strcmp(tp->call.class->system, group) == 0)
                        return tp;
        return NULL;
}

/* Unregister a trace_probe and probe_event: call with locking probe_lock */
static void unregister_trace_probe(struct trace_probe *tp)
{
        if (probe_is_return(tp))
                unregister_kretprobe(&tp->rp);
        else
                unregister_kprobe(&tp->rp.kp);
        list_del(&tp->list);
        unregister_probe_event(tp);
}

/* Register a trace_probe and probe_event */
static int register_trace_probe(struct trace_probe *tp)
{
        struct trace_probe *old_tp;
        int ret;

        mutex_lock(&probe_lock);

        /* register as an event */
        old_tp = find_probe_event(tp->call.name, tp->call.class->system);
        if (old_tp) {
                /* delete old event */
                unregister_trace_probe(old_tp);
                free_trace_probe(old_tp);
        }
        ret = register_probe_event(tp);
        if (ret) {
                pr_warning("Failed to register probe event(%d)\n", ret);
                goto end;
        }

        tp->rp.kp.flags |= KPROBE_FLAG_DISABLED;
        if (probe_is_return(tp))
                ret = register_kretprobe(&tp->rp);
        else
                ret = register_kprobe(&tp->rp.kp);

        if (ret) {
                pr_warning("Could not insert probe(%d)\n", ret);
                if (ret == -EILSEQ) {
                        pr_warning("Probing address(0x%p) is not an "
                                   "instruction boundary.\n",
                                   tp->rp.kp.addr);
                        ret = -EINVAL;
                }
                unregister_probe_event(tp);
        } else
                list_add_tail(&tp->list, &probe_list);
end:
        mutex_unlock(&probe_lock);
        return ret;
}

/* Split symbol and offset. */
static int split_symbol_offset(char *symbol, unsigned long *offset)
{
        char *tmp;
        int ret;

        if (!offset)
                return -EINVAL;

        tmp = strchr(symbol, '+');
        if (tmp) {
                /* skip sign because strict_strtol doesn't accept '+' */
                ret = strict_strtoul(tmp + 1, 0, offset);
                if (ret)
                        return ret;
                *tmp = '\0';
        } else
                *offset = 0;
        return 0;
}

#define PARAM_MAX_ARGS 16
#define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))

static int parse_probe_vars(char *arg, const struct fetch_type *t,
                            struct fetch_param *f, int is_return)
{
        int ret = 0;
        unsigned long param;

        if (strcmp(arg, "retval") == 0) {
                if (is_return)
                        f->fn = t->fetch[FETCH_MTD_retval];
                else
                        ret = -EINVAL;
        } else if (strncmp(arg, "stack", 5) == 0) {
                if (arg[5] == '\0') {
                        if (strcmp(t->name, DEFAULT_FETCH_TYPE_STR) == 0)
                                f->fn = fetch_stack_address;
                        else
                                ret = -EINVAL;
                } else if (isdigit(arg[5])) {
                        ret = strict_strtoul(arg + 5, 10, &param);
                        if (ret || param > PARAM_MAX_STACK)
                                ret = -EINVAL;
                        else {
                                f->fn = t->fetch[FETCH_MTD_stack];
                                f->data = (void *)param;
                        }
                } else
                        ret = -EINVAL;
        } else
                ret = -EINVAL;
        return ret;
}

/* Recursive argument parser */
static int __parse_probe_arg(char *arg, const struct fetch_type *t,
                             struct fetch_param *f, int is_return)
{
        int ret = 0;
        unsigned long param;
        long offset;
        char *tmp;

        switch (arg[0]) {
        case '$':
                ret = parse_probe_vars(arg + 1, t, f, is_return);
                break;
        case '%':       /* named register */
                ret = regs_query_register_offset(arg + 1);
                if (ret >= 0) {
                        f->fn = t->fetch[FETCH_MTD_reg];
                        f->data = (void *)(unsigned long)ret;
                        ret = 0;
                }
                break;
        case '@':       /* memory or symbol */
                if (isdigit(arg[1])) {
                        ret = strict_strtoul(arg + 1, 0, &param);
                        if (ret)
                                break;
                        f->fn = t->fetch[FETCH_MTD_memory];
                        f->data = (void *)param;
                } else {
                        ret = split_symbol_offset(arg + 1, &offset);
                        if (ret)
                                break;
                        f->data = alloc_symbol_cache(arg + 1, offset);
                        if (f->data)
                                f->fn = t->fetch[FETCH_MTD_symbol];
                }
                break;
        case '+':       /* deref memory */
        case '-':
                tmp = strchr(arg, '(');
                if (!tmp)
                        break;
                *tmp = '\0';
                ret = strict_strtol(arg + 1, 0, &offset);
                if (ret)
                        break;
                if (arg[0] == '-')
                        offset = -offset;
                arg = tmp + 1;
                tmp = strrchr(arg, ')');
                if (tmp) {
                        struct deref_fetch_param *dprm;
                        const struct fetch_type *t2 = find_fetch_type(NULL);
                        *tmp = '\0';
                        dprm = kzalloc(sizeof(struct deref_fetch_param),
                                       GFP_KERNEL);
                        if (!dprm)
                                return -ENOMEM;
                        dprm->offset = offset;
                        ret = __parse_probe_arg(arg, t2, &dprm->orig,
                                                is_return);
                        if (ret)
                                kfree(dprm);
                        else {
                                f->fn = t->fetch[FETCH_MTD_deref];
                                f->data = (void *)dprm;
                        }
                }
                break;
        }
        if (!ret && !f->fn) {   /* Parsed, but do not find fetch method */
                pr_info("%s type has no corresponding fetch method.\n",
                        t->name);
                ret = -EINVAL;
        }
        return ret;
}

/* String length checking wrapper */
static int parse_probe_arg(char *arg, struct trace_probe *tp,
                           struct probe_arg *parg, int is_return)
{
        const char *t;
        int ret;

        if (strlen(arg) > MAX_ARGSTR_LEN) {
                pr_info("Argument is too long.: %s\n",  arg);
                return -ENOSPC;
        }
        parg->comm = kstrdup(arg, GFP_KERNEL);
        if (!parg->comm) {
                pr_info("Failed to allocate memory for command '%s'.\n", arg);
                return -ENOMEM;
        }
        t = strchr(parg->comm, ':');
        if (t) {
                arg[t - parg->comm] = '\0';
                t++;
        }
        parg->type = find_fetch_type(t);
        if (!parg->type) {
                pr_info("Unsupported type: %s\n", t);
                return -EINVAL;
        }
        parg->offset = tp->size;
        tp->size += parg->type->size;
        ret = __parse_probe_arg(arg, parg->type, &parg->fetch, is_return);
        if (ret >= 0) {
                parg->fetch_size.fn = get_fetch_size_function(parg->type,
                                                              parg->fetch.fn);
                parg->fetch_size.data = parg->fetch.data;
        }
        return ret;
}

/* Return 1 if name is reserved or already used by another argument */
static int conflict_field_name(const char *name,
                               struct probe_arg *args, int narg)
{
        int i;
        for (i = 0; i < ARRAY_SIZE(reserved_field_names); i++)
                if (strcmp(reserved_field_names[i], name) == 0)
                        return 1;
        for (i = 0; i < narg; i++)
                if (strcmp(args[i].name, name) == 0)
                        return 1;
        return 0;
}

static int create_trace_probe(int argc, char **argv)
{
        /*
         * Argument syntax:
         *  - Add kprobe: p[:[GRP/]EVENT] KSYM[+OFFS]|KADDR [FETCHARGS]
         *  - Add kretprobe: r[:[GRP/]EVENT] KSYM[+0] [FETCHARGS]
         * Fetch args:
         *  $retval     : fetch return value
         *  $stack      : fetch stack address
         *  $stackN     : fetch Nth of stack (N:0-)
         *  @ADDR       : fetch memory at ADDR (ADDR should be in kernel)
         *  @SYM[+|-offs] : fetch memory at SYM +|- offs (SYM is a data symbol)
         *  %REG        : fetch register REG
         * Dereferencing memory fetch:
         *  +|-offs(ARG) : fetch memory at ARG +|- offs address.
         * Alias name of args:
         *  NAME=FETCHARG : set NAME as alias of FETCHARG.
         * Type of args:
         *  FETCHARG:TYPE : use TYPE instead of unsigned long.
         */
        struct trace_probe *tp;
        int i, ret = 0;
        int is_return = 0, is_delete = 0;
        char *symbol = NULL, *event = NULL, *group = NULL;
        char *arg;
        unsigned long offset = 0;
        void *addr = NULL;
        char buf[MAX_EVENT_NAME_LEN];

        /* argc must be >= 1 */
        if (argv[0][0] == 'p')
                is_return = 0;
        else if (argv[0][0] == 'r')
                is_return = 1;
        else if (argv[0][0] == '-')
                is_delete = 1;
        else {
                pr_info("Probe definition must be started with 'p', 'r' or"
                        " '-'.\n");
                return -EINVAL;
        }

        if (argv[0][1] == ':') {
                event = &argv[0][2];
                if (strchr(event, '/')) {
                        group = event;
                        event = strchr(group, '/') + 1;
                        event[-1] = '\0';
                        if (strlen(group) == 0) {
                                pr_info("Group name is not specified\n");
                                return -EINVAL;
                        }
                }
                if (strlen(event) == 0) {
                        pr_info("Event name is not specified\n");
                        return -EINVAL;
                }
        }
        if (!group)
                group = KPROBE_EVENT_SYSTEM;

        if (is_delete) {
                if (!event) {
                        pr_info("Delete command needs an event name.\n");
                        return -EINVAL;
                }
                mutex_lock(&probe_lock);
                tp = find_probe_event(event, group);
                if (!tp) {
                        mutex_unlock(&probe_lock);
                        pr_info("Event %s/%s doesn't exist.\n", group, event);
                        return -ENOENT;
                }
                /* delete an event */
                unregister_trace_probe(tp);
                free_trace_probe(tp);
                mutex_unlock(&probe_lock);
                return 0;
        }

        if (argc < 2) {
                pr_info("Probe point is not specified.\n");
                return -EINVAL;
        }
        if (isdigit(argv[1][0])) {
                if (is_return) {
                        pr_info("Return probe point must be a symbol.\n");
                        return -EINVAL;
                }
                /* an address specified */
                ret = strict_strtoul(&argv[1][0], 0, (unsigned long *)&addr);
                if (ret) {
                        pr_info("Failed to parse address.\n");
                        return ret;
                }
        } else {
                /* a symbol specified */
                symbol = argv[1];
                /* TODO: support .init module functions */
                ret = split_symbol_offset(symbol, &offset);
                if (ret) {
                        pr_info("Failed to parse symbol.\n");
                        return ret;
                }
                if (offset && is_return) {
                        pr_info("Return probe must be used without offset.\n");
                        return -EINVAL;
                }
        }
        argc -= 2; argv += 2;

        /* setup a probe */
        if (!event) {
                /* Make a new event name */
                if (symbol)
                        snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%s_%ld",
                                 is_return ? 'r' : 'p', symbol, offset);
                else
                        snprintf(buf, MAX_EVENT_NAME_LEN, "%c_0x%p",
                                 is_return ? 'r' : 'p', addr);
                event = buf;
        }
        tp = alloc_trace_probe(group, event, addr, symbol, offset, argc,
                               is_return);
        if (IS_ERR(tp)) {
                pr_info("Failed to allocate trace_probe.(%d)\n",
                        (int)PTR_ERR(tp));
                return PTR_ERR(tp);
        }

        /* parse arguments */
        ret = 0;
        for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
                /* Increment count for freeing args in error case */
                tp->nr_args++;

                /* Parse argument name */
                arg = strchr(argv[i], '=');
                if (arg) {
                        *arg++ = '\0';
                        tp->args[i].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);
                        tp->args[i].name = kstrdup(buf, GFP_KERNEL);
                }

                if (!tp->args[i].name) {
                        pr_info("Failed to allocate argument[%d] name.\n", i);
                        ret = -ENOMEM;
                        goto error;
                }

                if (!is_good_name(tp->args[i].name)) {
                        pr_info("Invalid argument[%d] name: %s\n",
                                i, tp->args[i].name);
                        ret = -EINVAL;
                        goto error;
                }

                if (conflict_field_name(tp->args[i].name, 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 = parse_probe_arg(arg, tp, &tp->args[i], is_return);
                if (ret) {
                        pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
                        goto error;
                }
        }

        ret = register_trace_probe(tp);
        if (ret)
                goto error;
        return 0;

error:
        free_trace_probe(tp);
        return ret;
}

static void cleanup_all_probes(void)
{
        struct trace_probe *tp;

        mutex_lock(&probe_lock);
        /* TODO: Use batch unregistration */
        while (!list_empty(&probe_list)) {
                tp = list_entry(probe_list.next, struct trace_probe, list);
                unregister_trace_probe(tp);
                free_trace_probe(tp);
        }
        mutex_unlock(&probe_lock);
}


/* 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_probe *tp = v;
        int i;

        seq_printf(m, "%c", probe_is_return(tp) ? 'r' : 'p');
        seq_printf(m, ":%s/%s", tp->call.class->system, tp->call.name);

        if (!tp->symbol)
                seq_printf(m, " 0x%p", tp->rp.kp.addr);
        else if (tp->rp.kp.offset)
                seq_printf(m, " %s+%u", probe_symbol(tp), tp->rp.kp.offset);
        else
                seq_printf(m, " %s", probe_symbol(tp));

        for (i = 0; i < tp->nr_args; i++)
                seq_printf(m, " %s=%s", tp->args[i].name, tp->args[i].comm);
        seq_printf(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)
{
        if ((file->f_mode & FMODE_WRITE) &&
            (file->f_flags & O_TRUNC))
                cleanup_all_probes();

        return seq_open(file, &probes_seq_op);
}

static int command_trace_probe(const char *buf)
{
        char **argv;
        int argc = 0, ret = 0;

        argv = argv_split(GFP_KERNEL, buf, &argc);
        if (!argv)
                return -ENOMEM;

        if (argc)
                ret = create_trace_probe(argc, argv);

        argv_free(argv);
        return ret;
}

#define WRITE_BUFSIZE 128

static ssize_t probes_write(struct file *file, const char __user *buffer,
                            size_t count, loff_t *ppos)
{
        char *kbuf, *tmp;
        int ret;
        size_t done;
        size_t size;

        kbuf = kmalloc(WRITE_BUFSIZE, GFP_KERNEL);
        if (!kbuf)
                return -ENOMEM;

        ret = done = 0;
        while (done < count) {
                size = count - done;
                if (size >= WRITE_BUFSIZE)
                        size = WRITE_BUFSIZE - 1;
                if (copy_from_user(kbuf, buffer + done, size)) {
                        ret = -EFAULT;
                        goto out;
                }
                kbuf[size] = '\0';
                tmp = strchr(kbuf, '\n');
                if (tmp) {
                        *tmp = '\0';
                        size = tmp - kbuf + 1;
                } else if (done + size < count) {
                        pr_warning("Line length is too long: "
                                   "Should be less than %d.", WRITE_BUFSIZE);
                        ret = -EINVAL;
                        goto out;
                }
                done += size;
                /* Remove comments */
                tmp = strchr(kbuf, '#');
                if (tmp)
                        *tmp = '\0';

                ret = command_trace_probe(kbuf);
                if (ret)
                        goto out;
        }
        ret = done;
out:
        kfree(kbuf);
        return ret;
}

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_probe *tp = v;

        seq_printf(m, "  %-44s %15lu %15lu\n", tp->call.name, tp->nhit,
                   tp->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,
};

/* Sum up total data length for dynamic arraies (strings) */
static __kprobes int __get_data_size(struct trace_probe *tp,
                                     struct pt_regs *regs)
{
        int i, ret = 0;
        u32 len;

        for (i = 0; i < tp->nr_args; i++)
                if (unlikely(tp->args[i].fetch_size.fn)) {
                        call_fetch(&tp->args[i].fetch_size, regs, &len);
                        ret += len;
                }

        return ret;
}

/* Store the value of each argument */
static __kprobes void store_trace_args(int ent_size, struct trace_probe *tp,
                                       struct pt_regs *regs,
                                       u8 *data, int maxlen)
{
        int i;
        u32 end = tp->size;
        u32 *dl;        /* Data (relative) location */

        for (i = 0; i < tp->nr_args; i++) {
                if (unlikely(tp->args[i].fetch_size.fn)) {
                        /*
                         * First, we set the relative location and
                         * maximum data length to *dl
                         */
                        dl = (u32 *)(data + tp->args[i].offset);
                        *dl = make_data_rloc(maxlen, end - tp->args[i].offset);
                        /* Then try to fetch string or dynamic array data */
                        call_fetch(&tp->args[i].fetch, regs, dl);
                        /* Reduce maximum length */
                        end += get_rloc_len(*dl);
                        maxlen -= get_rloc_len(*dl);
                        /* Trick here, convert data_rloc to data_loc */
                        *dl = convert_rloc_to_loc(*dl,
                                 ent_size + tp->args[i].offset);
                } else
                        /* Just fetching data normally */
                        call_fetch(&tp->args[i].fetch, regs,
                                   data + tp->args[i].offset);
        }
}

/* Kprobe handler */
static __kprobes void kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs)
{
        struct trace_probe *tp = container_of(kp, struct trace_probe, rp.kp);
        struct kprobe_trace_entry_head *entry;
        struct ring_buffer_event *event;
        struct ring_buffer *buffer;
        int size, dsize, pc;
        unsigned long irq_flags;
        struct ftrace_event_call *call = &tp->call;

        tp->nhit++;

        local_save_flags(irq_flags);
        pc = preempt_count();

        dsize = __get_data_size(tp, regs);
        size = sizeof(*entry) + tp->size + dsize;

        event = trace_current_buffer_lock_reserve(&buffer, call->event.type,
                                                  size, irq_flags, pc);
        if (!event)
                return;

        entry = ring_buffer_event_data(event);
        entry->ip = (unsigned long)kp->addr;
        store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);

        if (!filter_current_check_discard(buffer, call, entry, event))
                trace_nowake_buffer_unlock_commit(buffer, event, irq_flags, pc);
}

/* Kretprobe handler */
static __kprobes void kretprobe_trace_func(struct kretprobe_instance *ri,
                                          struct pt_regs *regs)
{
        struct trace_probe *tp = container_of(ri->rp, struct trace_probe, rp);
        struct kretprobe_trace_entry_head *entry;
        struct ring_buffer_event *event;
        struct ring_buffer *buffer;
        int size, pc, dsize;
        unsigned long irq_flags;
        struct ftrace_event_call *call = &tp->call;

        local_save_flags(irq_flags);
        pc = preempt_count();

        dsize = __get_data_size(tp, regs);
        size = sizeof(*entry) + tp->size + dsize;

        event = trace_current_buffer_lock_reserve(&buffer, call->event.type,
                                                  size, irq_flags, pc);
        if (!event)
                return;

        entry = ring_buffer_event_data(event);
        entry->func = (unsigned long)tp->rp.kp.addr;
        entry->ret_ip = (unsigned long)ri->ret_addr;
        store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);

        if (!filter_current_check_discard(buffer, call, entry, event))
                trace_nowake_buffer_unlock_commit(buffer, event, irq_flags, pc);
}

/* Event entry printers */
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);

        if (!trace_seq_printf(s, "%s: (", tp->call.name))
                goto partial;

        if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
                goto partial;

        if (!trace_seq_puts(s, ")"))
                goto partial;

        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 partial;

        if (!trace_seq_puts(s, "\n"))
                goto partial;

        return TRACE_TYPE_HANDLED;
partial:
        return TRACE_TYPE_PARTIAL_LINE;
}

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);

        if (!trace_seq_printf(s, "%s: (", tp->call.name))
                goto partial;

        if (!seq_print_ip_sym(s, field->ret_ip, flags | TRACE_ITER_SYM_OFFSET))
                goto partial;

        if (!trace_seq_puts(s, " <- "))
                goto partial;

        if (!seq_print_ip_sym(s, field->func, flags & ~TRACE_ITER_SYM_OFFSET))
                goto partial;

        if (!trace_seq_puts(s, ")"))
                goto partial;

        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 partial;

        if (!trace_seq_puts(s, "\n"))
                goto partial;

        return TRACE_TYPE_HANDLED;
partial:
        return TRACE_TYPE_PARTIAL_LINE;
}

static int probe_event_enable(struct ftrace_event_call *call)
{
        struct trace_probe *tp = (struct trace_probe *)call->data;

        tp->flags |= TP_FLAG_TRACE;
        if (probe_is_return(tp))
                return enable_kretprobe(&tp->rp);
        else
                return enable_kprobe(&tp->rp.kp);
}

static void probe_event_disable(struct ftrace_event_call *call)
{
        struct trace_probe *tp = (struct trace_probe *)call->data;

        tp->flags &= ~TP_FLAG_TRACE;
        if (!(tp->flags & (TP_FLAG_TRACE | TP_FLAG_PROFILE))) {
                if (probe_is_return(tp))
                        disable_kretprobe(&tp->rp);
                else
                        disable_kprobe(&tp->rp.kp);
        }
}

#undef DEFINE_FIELD
#define DEFINE_FIELD(type, item, name, is_signed)                       \
        do {                                                            \
                ret = trace_define_field(event_call, #type, name,       \
                                         offsetof(typeof(field), item), \
                                         sizeof(field.item), is_signed, \
                                         FILTER_OTHER);                 \
                if (ret)                                                \
                        return ret;                                     \
        } while (0)

static int kprobe_event_define_fields(struct ftrace_event_call *event_call)
{
        int ret, i;
        struct kprobe_trace_entry_head field;
        struct trace_probe *tp = (struct trace_probe *)event_call->data;

        DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
        /* Set argument names as fields */
        for (i = 0; i < tp->nr_args; i++) {
                ret = trace_define_field(event_call, tp->args[i].type->fmttype,
                                         tp->args[i].name,
                                         sizeof(field) + tp->args[i].offset,
                                         tp->args[i].type->size,
                                         tp->args[i].type->is_signed,
                                         FILTER_OTHER);
                if (ret)
                        return ret;
        }
        return 0;
}

static int kretprobe_event_define_fields(struct ftrace_event_call *event_call)
{
        int ret, i;
        struct kretprobe_trace_entry_head field;
        struct trace_probe *tp = (struct trace_probe *)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 < tp->nr_args; i++) {
                ret = trace_define_field(event_call, tp->args[i].type->fmttype,
                                         tp->args[i].name,
                                         sizeof(field) + tp->args[i].offset,
                                         tp->args[i].type->size,
                                         tp->args[i].type->is_signed,
                                         FILTER_OTHER);
                if (ret)
                        return ret;
        }
        return 0;
}

static int __set_print_fmt(struct trace_probe *tp, char *buf, int len)
{
        int i;
        int pos = 0;

        const char *fmt, *arg;

        if (!probe_is_return(tp)) {
                fmt = "(%lx)";
                arg = "REC->" FIELD_STRING_IP;
        } else {
                fmt = "(%lx <- %lx)";
                arg = "REC->" FIELD_STRING_FUNC ", REC->" FIELD_STRING_RETIP;
        }

        /* When len=0, we just calculate the needed length */
#define LEN_OR_ZERO (len ? len - pos : 0)

        pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", fmt);

        for (i = 0; i < tp->nr_args; i++) {
                pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=%s",
                                tp->args[i].name, tp->args[i].type->fmt);
        }

        pos += snprintf(buf + pos, LEN_OR_ZERO, "\", %s", arg);

        for (i = 0; i < tp->nr_args; i++) {
                if (strcmp(tp->args[i].type->name, "string") == 0)
                        pos += snprintf(buf + pos, LEN_OR_ZERO,
                                        ", __get_str(%s)",
                                        tp->args[i].name);
                else
                        pos += snprintf(buf + pos, LEN_OR_ZERO, ", REC->%s",
                                        tp->args[i].name);
        }

#undef LEN_OR_ZERO

        /* return the length of print_fmt */
        return pos;
}

static int set_print_fmt(struct trace_probe *tp)
{
        int len;
        char *print_fmt;

        /* First: called with 0 length to calculate the needed length */
        len = __set_print_fmt(tp, NULL, 0);
        print_fmt = kmalloc(len + 1, GFP_KERNEL);
        if (!print_fmt)
                return -ENOMEM;

        /* Second: actually write the @print_fmt */
        __set_print_fmt(tp, print_fmt, len + 1);
        tp->call.print_fmt = print_fmt;

        return 0;
}

#ifdef CONFIG_PERF_EVENTS

/* Kprobe profile handler */
static __kprobes void kprobe_perf_func(struct kprobe *kp,
                                         struct pt_regs *regs)
{
        struct trace_probe *tp = container_of(kp, struct trace_probe, rp.kp);
        struct ftrace_event_call *call = &tp->call;
        struct kprobe_trace_entry_head *entry;
        struct hlist_head *head;
        int size, __size, dsize;
        int rctx;

        dsize = __get_data_size(tp, regs);
        __size = sizeof(*entry) + tp->size + dsize;
        size = ALIGN(__size + sizeof(u32), sizeof(u64));
        size -= sizeof(u32);
        if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
                     "profile buffer not large enough"))
                return;

        entry = perf_trace_buf_prepare(size, call->event.type, regs, &rctx);
        if (!entry)
                return;

        entry->ip = (unsigned long)kp->addr;
        memset(&entry[1], 0, dsize);
        store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);

        head = this_cpu_ptr(call->perf_events);
        perf_trace_buf_submit(entry, size, rctx, entry->ip, 1, regs, head);
}

/* Kretprobe profile handler */
static __kprobes void kretprobe_perf_func(struct kretprobe_instance *ri,
                                            struct pt_regs *regs)
{
        struct trace_probe *tp = container_of(ri->rp, struct trace_probe, rp);
        struct ftrace_event_call *call = &tp->call;
        struct kretprobe_trace_entry_head *entry;
        struct hlist_head *head;
        int size, __size, dsize;
        int rctx;

        dsize = __get_data_size(tp, regs);
        __size = sizeof(*entry) + tp->size + dsize;
        size = ALIGN(__size + sizeof(u32), sizeof(u64));
        size -= sizeof(u32);
        if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
                     "profile buffer not large enough"))
                return;

        entry = perf_trace_buf_prepare(size, call->event.type, regs, &rctx);
        if (!entry)
                return;

        entry->func = (unsigned long)tp->rp.kp.addr;
        entry->ret_ip = (unsigned long)ri->ret_addr;
        store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);

        head = this_cpu_ptr(call->perf_events);
        perf_trace_buf_submit(entry, size, rctx, entry->ret_ip, 1, regs, head);
}

static int probe_perf_enable(struct ftrace_event_call *call)
{
        struct trace_probe *tp = (struct trace_probe *)call->data;

        tp->flags |= TP_FLAG_PROFILE;

        if (probe_is_return(tp))
                return enable_kretprobe(&tp->rp);
        else
                return enable_kprobe(&tp->rp.kp);
}

static void probe_perf_disable(struct ftrace_event_call *call)
{
        struct trace_probe *tp = (struct trace_probe *)call->data;

        tp->flags &= ~TP_FLAG_PROFILE;

        if (!(tp->flags & TP_FLAG_TRACE)) {
                if (probe_is_return(tp))
                        disable_kretprobe(&tp->rp);
                else
                        disable_kprobe(&tp->rp.kp);
        }
}
#endif  /* CONFIG_PERF_EVENTS */

static __kprobes
int kprobe_register(struct ftrace_event_call *event, enum trace_reg type)
{
        switch (type) {
        case TRACE_REG_REGISTER:
                return probe_event_enable(event);
        case TRACE_REG_UNREGISTER:
                probe_event_disable(event);
                return 0;

#ifdef CONFIG_PERF_EVENTS
        case TRACE_REG_PERF_REGISTER:
                return probe_perf_enable(event);
        case TRACE_REG_PERF_UNREGISTER:
                probe_perf_disable(event);
                return 0;
#endif
        }
        return 0;
}

static __kprobes
int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs)
{
        struct trace_probe *tp = container_of(kp, struct trace_probe, rp.kp);

        if (tp->flags & TP_FLAG_TRACE)
                kprobe_trace_func(kp, regs);
#ifdef CONFIG_PERF_EVENTS
        if (tp->flags & TP_FLAG_PROFILE)
                kprobe_perf_func(kp, regs);
#endif
        return 0;       /* We don't tweek kernel, so just return 0 */
}

static __kprobes
int kretprobe_dispatcher(struct kretprobe_instance *ri, struct pt_regs *regs)
{
        struct trace_probe *tp = container_of(ri->rp, struct trace_probe, rp);

        if (tp->flags & TP_FLAG_TRACE)
                kretprobe_trace_func(ri, regs);
#ifdef CONFIG_PERF_EVENTS
        if (tp->flags & TP_FLAG_PROFILE)
                kretprobe_perf_func(ri, regs);
#endif
        return 0;       /* We don't tweek kernel, so just return 0 */
}

static struct trace_event_functions kretprobe_funcs = {
        .trace          = print_kretprobe_event
};

static struct trace_event_functions kprobe_funcs = {
        .trace          = print_kprobe_event
};

static int register_probe_event(struct trace_probe *tp)
{
        struct ftrace_event_call *call = &tp->call;
        int ret;

        /* Initialize ftrace_event_call */
        INIT_LIST_HEAD(&call->class->fields);
        if (probe_is_return(tp)) {
                call->event.funcs = &kretprobe_funcs;
                call->class->define_fields = kretprobe_event_define_fields;
        } else {
                call->event.funcs = &kprobe_funcs;
                call->class->define_fields = kprobe_event_define_fields;
        }
        if (set_print_fmt(tp) < 0)
                return -ENOMEM;
        ret = register_ftrace_event(&call->event);
        if (!ret) {
                kfree(call->print_fmt);
                return -ENODEV;
        }
        call->flags = 0;
        call->class->reg = kprobe_register;
        call->data = tp;
        ret = trace_add_event_call(call);
        if (ret) {
                pr_info("Failed to register kprobe event: %s\n", call->name);
                kfree(call->print_fmt);
                unregister_ftrace_event(&call->event);
        }
        return ret;
}

static void unregister_probe_event(struct trace_probe *tp)
{
        /* tp->event is unregistered in trace_remove_event_call() */
        trace_remove_event_call(&tp->call);
        kfree(tp->call.print_fmt);
}

/* Make a debugfs interface for controling probe points */
static __init int init_kprobe_trace(void)
{
        struct dentry *d_tracer;
        struct dentry *entry;

        d_tracer = tracing_init_dentry();
        if (!d_tracer)
                return 0;

        entry = debugfs_create_file("kprobe_events", 0644, d_tracer,
                                    NULL, &kprobe_events_ops);

        /* Event list interface */
        if (!entry)
                pr_warning("Could not create debugfs "
                           "'kprobe_events' entry\n");

        /* Profile interface */
        entry = debugfs_create_file("kprobe_profile", 0444, d_tracer,
                                    NULL, &kprobe_profile_ops);

        if (!entry)
                pr_warning("Could not create debugfs "
                           "'kprobe_profile' entry\n");
        return 0;
}
fs_initcall(init_kprobe_trace);


#ifdef CONFIG_FTRACE_STARTUP_TEST

static 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 int kprobe_trace_self_tests_init(void)
{
        int ret, warn = 0;
        int (*target)(int, int, int, int, int, int);
        struct trace_probe *tp;

        target = kprobe_trace_selftest_target;

        pr_info("Testing kprobe tracing: ");

        ret = command_trace_probe("p:testprobe kprobe_trace_selftest_target "
                                  "$stack $stack0 +0($stack)");
        if (WARN_ON_ONCE(ret)) {
                pr_warning("error on probing function entry.\n");
                warn++;
        } else {
                /* Enable trace point */
                tp = find_probe_event("testprobe", KPROBE_EVENT_SYSTEM);
                if (WARN_ON_ONCE(tp == NULL)) {
                        pr_warning("error on getting new probe.\n");
                        warn++;
                } else
                        probe_event_enable(&tp->call);
        }

        ret = command_trace_probe("r:testprobe2 kprobe_trace_selftest_target "
                                  "$retval");
        if (WARN_ON_ONCE(ret)) {
                pr_warning("error on probing function return.\n");
                warn++;
        } else {
                /* Enable trace point */
                tp = find_probe_event("testprobe2", KPROBE_EVENT_SYSTEM);
                if (WARN_ON_ONCE(tp == NULL)) {
                        pr_warning("error on getting new probe.\n");
                        warn++;
                } else
                        probe_event_enable(&tp->call);
        }

        if (warn)
                goto end;

        ret = target(1, 2, 3, 4, 5, 6);

        ret = command_trace_probe("-:testprobe");
        if (WARN_ON_ONCE(ret)) {
                pr_warning("error on deleting a probe.\n");
                warn++;
        }

        ret = command_trace_probe("-:testprobe2");
        if (WARN_ON_ONCE(ret)) {
                pr_warning("error on deleting a probe.\n");
                warn++;
        }

end:
        cleanup_all_probes();
        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