/*
 * Common code for probe-based Dynamic events.
 *
 * 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
 *
 * This code was copied from kernel/trace/trace_kprobe.c written by
 * Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
 *
 * Updates to make this generic:
 * Copyright (C) IBM Corporation, 2010-2011
 * Author:     Srikar Dronamraju
 */

#include "trace_probe.h"

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

/* Printing function type */
#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)

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);
}

/* 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\\\"";

#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)
{
        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;
}

/* 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 update_deref_fetch_param(struct deref_fetch_param *data)
{
        if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
                update_deref_fetch_param(data->orig.data);
        else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
                update_symbol_cache(data->orig.data);
}

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);
}

/* Bitfield fetch function */
struct bitfield_fetch_param {
        struct fetch_param      orig;
        unsigned char           hi_shift;
        unsigned char           low_shift;
};

#define DEFINE_FETCH_bitfield(type)                                     \
static __kprobes void FETCH_FUNC_NAME(bitfield, type)(struct pt_regs *regs,\
                                            void *data, void *dest)     \
{                                                                       \
        struct bitfield_fetch_param *bprm = data;                       \
        type buf = 0;                                                   \
        call_fetch(&bprm->orig, regs, &buf);                            \
        if (buf) {                                                      \
                buf <<= bprm->hi_shift;                                 \
                buf >>= bprm->low_shift;                                \
        }                                                               \
        *(type *)dest = buf;                                            \
}

DEFINE_BASIC_FETCH_FUNCS(bitfield)
#define fetch_bitfield_string           NULL
#define fetch_bitfield_string_size      NULL

static __kprobes void
update_bitfield_fetch_param(struct bitfield_fetch_param *data)
{
        /*
         * Don't check the bitfield itself, because this must be the
         * last fetch function.
         */
        if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
                update_deref_fetch_param(data->orig.data);
        else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
                update_symbol_cache(data->orig.data);
}

static __kprobes void
free_bitfield_fetch_param(struct bitfield_fetch_param *data)
{
        /*
         * Don't check the bitfield itself, because this must be the
         * last fetch function.
         */
        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)

#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),                        \
ASSIGN_FETCH_FUNC(bitfield, 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 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;

        /* Special case: bitfield */
        if (*type == 'b') {
                unsigned long bs;

                type = strchr(type, '/');
                if (!type)
                        goto fail;

                type++;
                if (kstrtoul(type, 0, &bs))
                        goto fail;

                switch (bs) {
                case 8:
                        return find_fetch_type("u8");
                case 16:
                        return find_fetch_type("u16");
                case 32:
                        return find_fetch_type("u32");
                case 64:
                        return find_fetch_type("u64");
                default:
                        goto fail;
                }
        }

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

fail:
        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;
}

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

        if (!offset)
                return -EINVAL;

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

                *tmp = '\0';
        } else
                *offset = 0;

        return 0;
}

#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, bool 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 = kstrtoul(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, bool is_return, bool is_kprobe)
{
        unsigned long param;
        long offset;
        char *tmp;
        int ret;

        ret = 0;

        /* Until uprobe_events supports only reg arguments */
        if (!is_kprobe && arg[0] != '%')
                return -EINVAL;

        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 = kstrtoul(arg + 1, 0, &param);
                        if (ret)
                                break;

                        f->fn = t->fetch[FETCH_MTD_memory];
                        f->data = (void *)param;
                } else {
                        ret = traceprobe_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 */
                arg++;  /* Skip '+', because kstrtol() rejects it. */
        case '-':
                tmp = strchr(arg, '(');
                if (!tmp)
                        break;

                *tmp = '\0';
                ret = kstrtol(arg, 0, &offset);

                if (ret)
                        break;

                arg = tmp + 1;
                tmp = strrchr(arg, ')');

                if (tmp) {
                        struct deref_fetch_param        *dprm;
                        const struct fetch_type         *t2;

                        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,
                                                        is_kprobe);
                        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;
}

#define BYTES_TO_BITS(nb)       ((BITS_PER_LONG * (nb)) / sizeof(long))

/* Bitfield type needs to be parsed into a fetch function */
static int __parse_bitfield_probe_arg(const char *bf,
                                      const struct fetch_type *t,
                                      struct fetch_param *f)
{
        struct bitfield_fetch_param *bprm;
        unsigned long bw, bo;
        char *tail;

        if (*bf != 'b')
                return 0;

        bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
        if (!bprm)
                return -ENOMEM;

        bprm->orig = *f;
        f->fn = t->fetch[FETCH_MTD_bitfield];
        f->data = (void *)bprm;
        bw = simple_strtoul(bf + 1, &tail, 0);  /* Use simple one */

        if (bw == 0 || *tail != '@')
                return -EINVAL;

        bf = tail + 1;
        bo = simple_strtoul(bf, &tail, 0);

        if (tail == bf || *tail != '/')
                return -EINVAL;

        bprm->hi_shift = BYTES_TO_BITS(t->size) - (bw + bo);
        bprm->low_shift = bprm->hi_shift + bo;

        return (BYTES_TO_BITS(t->size) < (bw + bo)) ? -EINVAL : 0;
}

/* String length checking wrapper */
int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
                struct probe_arg *parg, bool is_return, bool is_kprobe)
{
        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 = *size;
        *size += parg->type->size;
        ret = parse_probe_arg(arg, parg->type, &parg->fetch, is_return, is_kprobe);

        if (ret >= 0 && t != NULL)
                ret = __parse_bitfield_probe_arg(t, parg->type, &parg->fetch);

        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 */
int traceprobe_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;
}

void traceprobe_update_arg(struct probe_arg *arg)
{
        if (CHECK_FETCH_FUNCS(bitfield, arg->fetch.fn))
                update_bitfield_fetch_param(arg->fetch.data);
        else if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))
                update_deref_fetch_param(arg->fetch.data);
        else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))
                update_symbol_cache(arg->fetch.data);
}

void traceprobe_free_probe_arg(struct probe_arg *arg)
{
        if (CHECK_FETCH_FUNCS(bitfield, arg->fetch.fn))
                free_bitfield_fetch_param(arg->fetch.data);
        else 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);
}

int traceprobe_command(const char *buf, int (*createfn)(int, char **))
{
        char **argv;
        int argc, ret;

        argc = 0;
        ret = 0;
        argv = argv_split(GFP_KERNEL, buf, &argc);
        if (!argv)
                return -ENOMEM;

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

        argv_free(argv);

        return ret;
}

#define WRITE_BUFSIZE  4096

ssize_t traceprobe_probes_write(struct file *file, const char __user *buffer,
                                size_t count, loff_t *ppos,
                                int (*createfn)(int, char **))
{
        char *kbuf, *tmp;
        int ret = 0;
        size_t done = 0;
        size_t size;

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

        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 = traceprobe_command(kbuf, createfn);
                if (ret)
                        goto out;
        }
        ret = done;

out:
        kfree(kbuf);

        return ret;
}