// SPDX-License-Identifier: GPL-2.0
/*
 * Common code for probe-based Dynamic events.
 *
 * 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
 */
#define pr_fmt(fmt)     "trace_probe: " fmt

#include <linux/bpf.h>
#include <linux/fs.h>

#include "trace_btf.h"
#include "trace_probe.h"

#undef C
#define C(a, b)         b

static const char *trace_probe_err_text[] = { ERRORS };

static 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  in basic type function template */
#define DEFINE_BASIC_PRINT_TYPE_FUNC(tname, type, fmt)                  \
int PRINT_TYPE_FUNC_NAME(tname)(struct trace_seq *s, void *data, void *ent)\
{                                                                       \
        trace_seq_printf(s, fmt, *(type *)data);                        \
        return !trace_seq_has_overflowed(s);                            \
}                                                                       \
const char PRINT_TYPE_FMT_NAME(tname)[] = fmt;

DEFINE_BASIC_PRINT_TYPE_FUNC(u8,  u8,  "%u")
DEFINE_BASIC_PRINT_TYPE_FUNC(u16, u16, "%u")
DEFINE_BASIC_PRINT_TYPE_FUNC(u32, u32, "%u")
DEFINE_BASIC_PRINT_TYPE_FUNC(u64, u64, "%Lu")
DEFINE_BASIC_PRINT_TYPE_FUNC(s8,  s8,  "%d")
DEFINE_BASIC_PRINT_TYPE_FUNC(s16, s16, "%d")
DEFINE_BASIC_PRINT_TYPE_FUNC(s32, s32, "%d")
DEFINE_BASIC_PRINT_TYPE_FUNC(s64, s64, "%Ld")
DEFINE_BASIC_PRINT_TYPE_FUNC(x8,  u8,  "0x%x")
DEFINE_BASIC_PRINT_TYPE_FUNC(x16, u16, "0x%x")
DEFINE_BASIC_PRINT_TYPE_FUNC(x32, u32, "0x%x")
DEFINE_BASIC_PRINT_TYPE_FUNC(x64, u64, "0x%Lx")
DEFINE_BASIC_PRINT_TYPE_FUNC(char, u8, "'%c'")

int PRINT_TYPE_FUNC_NAME(symbol)(struct trace_seq *s, void *data, void *ent)
{
        trace_seq_printf(s, "%pS", (void *)*(unsigned long *)data);
        return !trace_seq_has_overflowed(s);
}
const char PRINT_TYPE_FMT_NAME(symbol)[] = "%pS";

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

        if (!len)
                trace_seq_puts(s, FAULT_STRING);
        else
                trace_seq_printf(s, "\"%s\"",
                                 (const char *)get_loc_data(data, ent));
        return !trace_seq_has_overflowed(s);
}

const char PRINT_TYPE_FMT_NAME(string)[] = "\\\"%s\\\"";

/* Fetch type information table */
static const struct fetch_type probe_fetch_types[] = {
        /* Special types */
        __ASSIGN_FETCH_TYPE("string", string, string, sizeof(u32), 1, 1,
                            "__data_loc char[]"),
        __ASSIGN_FETCH_TYPE("ustring", string, string, sizeof(u32), 1, 1,
                            "__data_loc char[]"),
        __ASSIGN_FETCH_TYPE("symstr", string, string, sizeof(u32), 1, 1,
                            "__data_loc char[]"),
        /* Basic types */
        ASSIGN_FETCH_TYPE(u8,  u8,  0),
        ASSIGN_FETCH_TYPE(u16, u16, 0),
        ASSIGN_FETCH_TYPE(u32, u32, 0),
        ASSIGN_FETCH_TYPE(u64, u64, 0),
        ASSIGN_FETCH_TYPE(s8,  u8,  1),
        ASSIGN_FETCH_TYPE(s16, u16, 1),
        ASSIGN_FETCH_TYPE(s32, u32, 1),
        ASSIGN_FETCH_TYPE(s64, u64, 1),
        ASSIGN_FETCH_TYPE_ALIAS(x8,  u8,  u8,  0),
        ASSIGN_FETCH_TYPE_ALIAS(x16, u16, u16, 0),
        ASSIGN_FETCH_TYPE_ALIAS(x32, u32, u32, 0),
        ASSIGN_FETCH_TYPE_ALIAS(x64, u64, u64, 0),
        ASSIGN_FETCH_TYPE_ALIAS(char, u8, u8,  0),
        ASSIGN_FETCH_TYPE_ALIAS(symbol, ADDR_FETCH_TYPE, ADDR_FETCH_TYPE, 0),

        ASSIGN_FETCH_TYPE_END
};

static const struct fetch_type *find_fetch_type(const char *type, unsigned long flags)
{
        int i;

        /* Reject the symbol/symstr for uprobes */
        if (type && (flags & TPARG_FL_USER) &&
            (!strcmp(type, "symbol") || !strcmp(type, "symstr")))
                return NULL;

        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", flags);
                case 16:
                        return find_fetch_type("u16", flags);
                case 32:
                        return find_fetch_type("u32", flags);
                case 64:
                        return find_fetch_type("u64", flags);
                default:
                        goto fail;
                }
        }

        for (i = 0; probe_fetch_types[i].name; i++) {
                if (strcmp(type, probe_fetch_types[i].name) == 0)
                        return &probe_fetch_types[i];
        }

fail:
        return NULL;
}

static struct trace_probe_log trace_probe_log;
extern struct mutex dyn_event_ops_mutex;

const char *trace_probe_log_init(const char *subsystem, int argc, const char **argv)
{
        lockdep_assert_held(&dyn_event_ops_mutex);

        trace_probe_log.subsystem = subsystem;
        trace_probe_log.argc = argc;
        trace_probe_log.argv = argv;
        trace_probe_log.index = 0;
        return subsystem;
}

void trace_probe_log_clear(void)
{
        lockdep_assert_held(&dyn_event_ops_mutex);

        memset(&trace_probe_log, 0, sizeof(trace_probe_log));
}

void trace_probe_log_set_index(int index)
{
        lockdep_assert_held(&dyn_event_ops_mutex);

        trace_probe_log.index = index;
}

void __trace_probe_log_err(int offset, int err_type)
{
        char *command, *p;
        int i, len = 0, pos = 0;

        lockdep_assert_held(&dyn_event_ops_mutex);

        if (!trace_probe_log.argv)
                return;

        /* Recalculate the length and allocate buffer */
        for (i = 0; i < trace_probe_log.argc; i++) {
                if (i == trace_probe_log.index)
                        pos = len;
                len += strlen(trace_probe_log.argv[i]) + 1;
        }
        command = kzalloc(len, GFP_KERNEL);
        if (!command)
                return;

        if (trace_probe_log.index >= trace_probe_log.argc) {
                /**
                 * Set the error position is next to the last arg + space.
                 * Note that len includes the terminal null and the cursor
                 * appears at pos + 1.
                 */
                pos = len;
                offset = 0;
        }

        /* And make a command string from argv array */
        p = command;
        for (i = 0; i < trace_probe_log.argc; i++) {
                len = strlen(trace_probe_log.argv[i]);
                memcpy(p, trace_probe_log.argv[i], len);
                p[len] = ' ';
                p += len + 1;
        }
        *(p - 1) = '\0';

        tracing_log_err(NULL, trace_probe_log.subsystem, command,
                        trace_probe_err_text, err_type, pos + offset);

        kfree(command);
}

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

        if (!offset)
                return -EINVAL;

        tmp = strpbrk(symbol, "+-");
        if (tmp) {
                ret = kstrtol(tmp, 0, offset);
                if (ret)
                        return ret;
                *tmp = '\0';
        } else
                *offset = 0;

        return 0;
}

/**
 * traceprobe_parse_event_name() - Parse a string into group and event names
 * @pevent: A pointer to the string to be parsed.
 * @pgroup: A pointer to the group name.
 * @buf:    A buffer to store the parsed group name.
 * @offset: The offset of the string in the original user command, for logging.
 *
 * This parses a string with the format `[GROUP/][EVENT]` or `[GROUP.][EVENT]`
 * (either GROUP or EVENT or both must be specified).
 * Since the parsed group name is stored in @buf, the caller must ensure @buf
 * is at least MAX_EVENT_NAME_LEN bytes.
 *
 * Return: 0 on success, or -EINVAL on failure.
 *
 * If success, *@pevent is updated to point to the event name part of the
 * original string, or NULL if there is no event name.
 * Also, *@pgroup is updated to point to the parsed group which is stored
 * in @buf, or NULL if there is no group name.
 */
int traceprobe_parse_event_name(const char **pevent, const char **pgroup,
                                char *buf, int offset)
{
        const char *slash, *event = *pevent;
        int len;

        slash = strchr(event, '/');
        if (!slash)
                slash = strchr(event, '.');

        if (slash) {
                if (slash == event) {
                        trace_probe_log_err(offset, NO_GROUP_NAME);
                        return -EINVAL;
                }
                if (slash - event + 1 > MAX_EVENT_NAME_LEN) {
                        trace_probe_log_err(offset, GROUP_TOO_LONG);
                        return -EINVAL;
                }
                strscpy(buf, event, slash - event + 1);
                if (!is_good_system_name(buf)) {
                        trace_probe_log_err(offset, BAD_GROUP_NAME);
                        return -EINVAL;
                }
                *pgroup = buf;
                *pevent = slash + 1;
                offset += slash - event + 1;
                event = *pevent;
        }
        len = strlen(event);
        if (len == 0) {
                if (slash) {
                        *pevent = NULL;
                        return 0;
                }
                trace_probe_log_err(offset, NO_EVENT_NAME);
                return -EINVAL;
        } else if (len >= MAX_EVENT_NAME_LEN) {
                trace_probe_log_err(offset, EVENT_TOO_LONG);
                return -EINVAL;
        }
        if (!is_good_name(event)) {
                trace_probe_log_err(offset, BAD_EVENT_NAME);
                return -EINVAL;
        }
        return 0;
}

static int parse_trace_event_arg(char *arg, struct fetch_insn *code,
                                 struct traceprobe_parse_context *ctx)
{
        struct ftrace_event_field *field;
        struct list_head *head;

        head = trace_get_fields(ctx->event);
        list_for_each_entry(field, head, link) {
                if (!strcmp(arg, field->name)) {
                        code->op = FETCH_OP_TP_ARG;
                        code->data = field;
                        return 0;
                }
        }
        return -ENOENT;
}

#ifdef CONFIG_PROBE_EVENTS_BTF_ARGS

static u32 btf_type_int(const struct btf_type *t)
{
        return *(u32 *)(t + 1);
}

static bool btf_type_is_char_ptr(struct btf *btf, const struct btf_type *type)
{
        const struct btf_type *real_type;
        u32 intdata;
        s32 tid;

        real_type = btf_type_skip_modifiers(btf, type->type, &tid);
        if (!real_type)
                return false;

        if (BTF_INFO_KIND(real_type->info) != BTF_KIND_INT)
                return false;

        intdata = btf_type_int(real_type);
        return !(BTF_INT_ENCODING(intdata) & BTF_INT_SIGNED)
                && BTF_INT_BITS(intdata) == 8;
}

static bool btf_type_is_char_array(struct btf *btf, const struct btf_type *type)
{
        const struct btf_type *real_type;
        const struct btf_array *array;
        u32 intdata;
        s32 tid;

        if (BTF_INFO_KIND(type->info) != BTF_KIND_ARRAY)
                return false;

        array = (const struct btf_array *)(type + 1);

        real_type = btf_type_skip_modifiers(btf, array->type, &tid);

        intdata = btf_type_int(real_type);
        return !(BTF_INT_ENCODING(intdata) & BTF_INT_SIGNED)
                && BTF_INT_BITS(intdata) == 8;
}

static int check_prepare_btf_string_fetch(char *typename,
                                struct fetch_insn **pcode,
                                struct traceprobe_parse_context *ctx)
{
        struct btf *btf = ctx->btf;

        if (!btf || !ctx->last_type)
                return 0;

        /* char [] does not need any change. */
        if (btf_type_is_char_array(btf, ctx->last_type))
                return 0;

        /* char * requires dereference the pointer. */
        if (btf_type_is_char_ptr(btf, ctx->last_type)) {
                struct fetch_insn *code = *pcode + 1;

                if (code->op == FETCH_OP_END) {
                        trace_probe_log_err(ctx->offset, TOO_MANY_OPS);
                        return -E2BIG;
                }
                if (typename[0] == 'u')
                        code->op = FETCH_OP_UDEREF;
                else
                        code->op = FETCH_OP_DEREF;
                code->offset = 0;
                *pcode = code;
                return 0;
        }
        /* Other types are not available for string */
        trace_probe_log_err(ctx->offset, BAD_TYPE4STR);
        return -EINVAL;
}

static const char *fetch_type_from_btf_type(struct btf *btf,
                                        const struct btf_type *type,
                                        struct traceprobe_parse_context *ctx)
{
        u32 intdata;

        /* TODO: const char * could be converted as a string */
        switch (BTF_INFO_KIND(type->info)) {
        case BTF_KIND_ENUM:
                /* enum is "int", so convert to "s32" */
                return "s32";
        case BTF_KIND_ENUM64:
                return "s64";
        case BTF_KIND_PTR:
                /* pointer will be converted to "x??" */
                if (IS_ENABLED(CONFIG_64BIT))
                        return "x64";
                else
                        return "x32";
        case BTF_KIND_INT:
                intdata = btf_type_int(type);
                if (BTF_INT_ENCODING(intdata) & BTF_INT_SIGNED) {
                        switch (BTF_INT_BITS(intdata)) {
                        case 8:
                                return "s8";
                        case 16:
                                return "s16";
                        case 32:
                                return "s32";
                        case 64:
                                return "s64";
                        }
                } else {        /* unsigned */
                        switch (BTF_INT_BITS(intdata)) {
                        case 8:
                                return "u8";
                        case 16:
                                return "u16";
                        case 32:
                                return "u32";
                        case 64:
                                return "u64";
                        }
                        /* bitfield, size is encoded in the type */
                        ctx->last_bitsize = BTF_INT_BITS(intdata);
                        ctx->last_bitoffs += BTF_INT_OFFSET(intdata);
                        return "u64";
                }
        }
        /* TODO: support other types */

        return NULL;
}

static int query_btf_context(struct traceprobe_parse_context *ctx)
{
        const struct btf_param *param;
        const struct btf_type *type;
        struct btf *btf;
        s32 nr;

        if (ctx->btf)
                return 0;

        if (!ctx->funcname)
                return -EINVAL;

        type = btf_find_func_proto(ctx->funcname, &btf);
        if (!type)
                return -ENOENT;

        ctx->btf = btf;
        ctx->proto = type;

        /* ctx->params is optional, since func(void) will not have params. */
        nr = 0;
        param = btf_get_func_param(type, &nr);
        if (!IS_ERR_OR_NULL(param)) {
                /* Hide the first 'data' argument of tracepoint */
                if (ctx->flags & TPARG_FL_TPOINT) {
                        nr--;
                        param++;
                }
        }

        if (nr > 0) {
                ctx->nr_params = nr;
                ctx->params = param;
        } else {
                ctx->nr_params = 0;
                ctx->params = NULL;
        }

        return 0;
}

static void clear_btf_context(struct traceprobe_parse_context *ctx)
{
        if (ctx->btf) {
                btf_put(ctx->btf);
                ctx->btf = NULL;
                ctx->proto = NULL;
                ctx->params = NULL;
                ctx->nr_params = 0;
        }
}

/* Return 1 if the field separator is arrow operator ('->') */
static int split_next_field(char *varname, char **next_field,
                            struct traceprobe_parse_context *ctx)
{
        char *field;
        int ret = 0;

        field = strpbrk(varname, ".-");
        if (field) {
                if (field[0] == '-' && field[1] == '>') {
                        field[0] = '\0';
                        field += 2;
                        ret = 1;
                } else if (field[0] == '.') {
                        field[0] = '\0';
                        field += 1;
                } else {
                        trace_probe_log_err(ctx->offset + field - varname, BAD_HYPHEN);
                        return -EINVAL;
                }
                *next_field = field;
        }

        return ret;
}

/*
 * Parse the field of data structure. The @type must be a pointer type
 * pointing the target data structure type.
 */
static int parse_btf_field(char *fieldname, const struct btf_type *type,
                           struct fetch_insn **pcode, struct fetch_insn *end,
                           struct traceprobe_parse_context *ctx)
{
        struct fetch_insn *code = *pcode;
        const struct btf_member *field;
        u32 bitoffs, anon_offs;
        char *next;
        int is_ptr;
        s32 tid;

        do {
                /* Outer loop for solving arrow operator ('->') */
                if (BTF_INFO_KIND(type->info) != BTF_KIND_PTR) {
                        trace_probe_log_err(ctx->offset, NO_PTR_STRCT);
                        return -EINVAL;
                }
                /* Convert a struct pointer type to a struct type */
                type = btf_type_skip_modifiers(ctx->btf, type->type, &tid);
                if (!type) {
                        trace_probe_log_err(ctx->offset, BAD_BTF_TID);
                        return -EINVAL;
                }

                bitoffs = 0;
                do {
                        /* Inner loop for solving dot operator ('.') */
                        next = NULL;
                        is_ptr = split_next_field(fieldname, &next, ctx);
                        if (is_ptr < 0)
                                return is_ptr;

                        anon_offs = 0;
                        field = btf_find_struct_member(ctx->btf, type, fieldname,
                                                       &anon_offs);
                        if (IS_ERR(field)) {
                                trace_probe_log_err(ctx->offset, BAD_BTF_TID);
                                return PTR_ERR(field);
                        }
                        if (!field) {
                                trace_probe_log_err(ctx->offset, NO_BTF_FIELD);
                                return -ENOENT;
                        }
                        /* Add anonymous structure/union offset */
                        bitoffs += anon_offs;

                        /* Accumulate the bit-offsets of the dot-connected fields */
                        if (btf_type_kflag(type)) {
                                bitoffs += BTF_MEMBER_BIT_OFFSET(field->offset);
                                ctx->last_bitsize = BTF_MEMBER_BITFIELD_SIZE(field->offset);
                        } else {
                                bitoffs += field->offset;
                                ctx->last_bitsize = 0;
                        }

                        type = btf_type_skip_modifiers(ctx->btf, field->type, &tid);
                        if (!type) {
                                trace_probe_log_err(ctx->offset, BAD_BTF_TID);
                                return -EINVAL;
                        }

                        ctx->offset += next - fieldname;
                        fieldname = next;
                } while (!is_ptr && fieldname);

                if (++code == end) {
                        trace_probe_log_err(ctx->offset, TOO_MANY_OPS);
                        return -EINVAL;
                }
                code->op = FETCH_OP_DEREF;      /* TODO: user deref support */
                code->offset = bitoffs / 8;
                *pcode = code;

                ctx->last_bitoffs = bitoffs % 8;
                ctx->last_type = type;
        } while (fieldname);

        return 0;
}

static int __store_entry_arg(struct trace_probe *tp, int argnum);

static int parse_btf_arg(char *varname,
                         struct fetch_insn **pcode, struct fetch_insn *end,
                         struct traceprobe_parse_context *ctx)
{
        struct fetch_insn *code = *pcode;
        const struct btf_param *params;
        const struct btf_type *type;
        char *field = NULL;
        int i, is_ptr, ret;
        u32 tid;

        if (WARN_ON_ONCE(!ctx->funcname))
                return -EINVAL;

        is_ptr = split_next_field(varname, &field, ctx);
        if (is_ptr < 0)
                return is_ptr;
        if (!is_ptr && field) {
                /* dot-connected field on an argument is not supported. */
                trace_probe_log_err(ctx->offset + field - varname,
                                    NOSUP_DAT_ARG);
                return -EOPNOTSUPP;
        }

        if (ctx->flags & TPARG_FL_RETURN && !strcmp(varname, "$retval")) {
                code->op = FETCH_OP_RETVAL;
                /* Check whether the function return type is not void */
                if (query_btf_context(ctx) == 0) {
                        if (ctx->proto->type == 0) {
                                trace_probe_log_err(ctx->offset, NO_RETVAL);
                                return -ENOENT;
                        }
                        tid = ctx->proto->type;
                        goto found;
                }
                if (field) {
                        trace_probe_log_err(ctx->offset + field - varname,
                                            NO_BTF_ENTRY);
                        return -ENOENT;
                }
                return 0;
        }

        if (!ctx->btf) {
                ret = query_btf_context(ctx);
                if (ret < 0 || ctx->nr_params == 0) {
                        trace_probe_log_err(ctx->offset, NO_BTF_ENTRY);
                        return -ENOENT;
                }
        }
        params = ctx->params;

        for (i = 0; i < ctx->nr_params; i++) {
                const char *name = btf_name_by_offset(ctx->btf, params[i].name_off);

                if (name && !strcmp(name, varname)) {
                        if (tparg_is_function_entry(ctx->flags)) {
                                code->op = FETCH_OP_ARG;
                                if (ctx->flags & TPARG_FL_TPOINT)
                                        code->param = i + 1;
                                else
                                        code->param = i;
                        } else if (tparg_is_function_return(ctx->flags)) {
                                code->op = FETCH_OP_EDATA;
                                ret = __store_entry_arg(ctx->tp, i);
                                if (ret < 0) {
                                        /* internal error */
                                        return ret;
                                }
                                code->offset = ret;
                        }
                        tid = params[i].type;
                        goto found;
                }
        }
        trace_probe_log_err(ctx->offset, NO_BTFARG);
        return -ENOENT;

found:
        type = btf_type_skip_modifiers(ctx->btf, tid, &tid);
        if (!type) {
                trace_probe_log_err(ctx->offset, BAD_BTF_TID);
                return -EINVAL;
        }
        /* Initialize the last type information */
        ctx->last_type = type;
        ctx->last_bitoffs = 0;
        ctx->last_bitsize = 0;
        if (field) {
                ctx->offset += field - varname;
                return parse_btf_field(field, type, pcode, end, ctx);
        }
        return 0;
}

static const struct fetch_type *find_fetch_type_from_btf_type(
                                        struct traceprobe_parse_context *ctx)
{
        struct btf *btf = ctx->btf;
        const char *typestr = NULL;

        if (btf && ctx->last_type)
                typestr = fetch_type_from_btf_type(btf, ctx->last_type, ctx);

        return find_fetch_type(typestr, ctx->flags);
}

static int parse_btf_bitfield(struct fetch_insn **pcode,
                              struct traceprobe_parse_context *ctx)
{
        struct fetch_insn *code = *pcode;

        if ((ctx->last_bitsize % 8 == 0) && ctx->last_bitoffs == 0)
                return 0;

        code++;
        if (code->op != FETCH_OP_NOP) {
                trace_probe_log_err(ctx->offset, TOO_MANY_OPS);
                return -EINVAL;
        }
        *pcode = code;

        code->op = FETCH_OP_MOD_BF;
        code->lshift = 64 - (ctx->last_bitsize + ctx->last_bitoffs);
        code->rshift = 64 - ctx->last_bitsize;
        code->basesize = 64 / 8;
        return 0;
}

#else
static void clear_btf_context(struct traceprobe_parse_context *ctx)
{
        ctx->btf = NULL;
}

static int query_btf_context(struct traceprobe_parse_context *ctx)
{
        return -EOPNOTSUPP;
}

static int parse_btf_arg(char *varname,
                         struct fetch_insn **pcode, struct fetch_insn *end,
                         struct traceprobe_parse_context *ctx)
{
        trace_probe_log_err(ctx->offset, NOSUP_BTFARG);
        return -EOPNOTSUPP;
}

static int parse_btf_bitfield(struct fetch_insn **pcode,
                              struct traceprobe_parse_context *ctx)
{
        trace_probe_log_err(ctx->offset, NOSUP_BTFARG);
        return -EOPNOTSUPP;
}

#define find_fetch_type_from_btf_type(ctx)              \
        find_fetch_type(NULL, ctx->flags)

static int check_prepare_btf_string_fetch(char *typename,
                                struct fetch_insn **pcode,
                                struct traceprobe_parse_context *ctx)
{
        return 0;
}

#endif

#ifdef CONFIG_HAVE_FUNCTION_ARG_ACCESS_API

static void store_entry_arg_at(struct fetch_insn *code, int argnum, int offset)
{
        code[0].op = FETCH_OP_ARG;
        code[0].param = argnum;
        code[1].op = FETCH_OP_ST_EDATA;
        code[1].offset = offset;
}

static int get_entry_arg_max_offset(struct probe_entry_arg *earg)
{
        int i, max_offset = 0;

        /*
         * earg->code[] array has an operation sequence which is run in
         * the entry handler.
         * The sequence stopped by FETCH_OP_END and each data stored in
         * the entry data buffer by FETCH_OP_ST_EDATA. The FETCH_OP_ST_EDATA
         * stores the data at the data buffer + its offset, and all data are
         * "unsigned long" size. The offset must be increased when a data is
         * stored. Thus we need to find the last FETCH_OP_ST_EDATA in the
         * code array.
         */
        for (i = 0; i < earg->size - 1 && earg->code[i].op != FETCH_OP_END; i++) {
                if (earg->code[i].op == FETCH_OP_ST_EDATA)
                        if (earg->code[i].offset > max_offset)
                                max_offset = earg->code[i].offset;
        }
        return max_offset;
}

/*
 * Add the entry code to store the 'argnum'th parameter and return the offset
 * in the entry data buffer where the data will be stored.
 */
static int __store_entry_arg(struct trace_probe *tp, int argnum)
{
        struct probe_entry_arg *earg = tp->entry_arg;
        int i, offset, last_offset = 0;

        if (!earg) {
                earg = kzalloc_obj(*tp->entry_arg);
                if (!earg)
                        return -ENOMEM;
                earg->size = 2 * tp->nr_args + 1;
                earg->code = kzalloc_objs(struct fetch_insn, earg->size);
                if (!earg->code) {
                        kfree(earg);
                        return -ENOMEM;
                }
                /* Fill the code buffer with 'end' to simplify it */
                for (i = 0; i < earg->size; i++)
                        earg->code[i].op = FETCH_OP_END;
                tp->entry_arg = earg;
                store_entry_arg_at(earg->code, argnum, 0);
                return 0;
        }

        /*
         * NOTE: if anyone change the following rule, please rewrite this.
         * The entry code array is filled with the pair of
         *
         * [FETCH_OP_ARG(argnum)]
         * [FETCH_OP_ST_EDATA(offset of entry data buffer)]
         *
         * and the rest of entries are filled with [FETCH_OP_END].
         * The offset should be incremented, thus the last pair should
         * have the largest offset.
         */

        /* Search the offset for the sprcified argnum. */
        for (i = 0; i < earg->size - 1 && earg->code[i].op != FETCH_OP_END; i += 2) {
                if (WARN_ON_ONCE(earg->code[i].op != FETCH_OP_ARG))
                        return -EINVAL;

                if (earg->code[i].param != argnum)
                        continue;

                if (WARN_ON_ONCE(earg->code[i + 1].op != FETCH_OP_ST_EDATA))
                        return -EINVAL;

                return earg->code[i + 1].offset;
        }
        /* Not found, append new entry if possible. */
        if (i >= earg->size - 1)
                return -ENOSPC;

        /* The last entry must have the largest offset. */
        if (i != 0) {
                if (WARN_ON_ONCE(earg->code[i - 1].op != FETCH_OP_ST_EDATA))
                        return -EINVAL;
                last_offset = earg->code[i - 1].offset;
        }

        offset = last_offset + sizeof(unsigned long);
        store_entry_arg_at(&earg->code[i], argnum, offset);
        return offset;
}

int traceprobe_get_entry_data_size(struct trace_probe *tp)
{
        struct probe_entry_arg *earg = tp->entry_arg;

        if (!earg)
                return 0;

        return get_entry_arg_max_offset(earg) + sizeof(unsigned long);
}

void store_trace_entry_data(void *edata, struct trace_probe *tp, struct pt_regs *regs)
{
        struct probe_entry_arg *earg = tp->entry_arg;
        unsigned long val = 0;
        int i;

        if (!earg)
                return;

        for (i = 0; i < earg->size; i++) {
                struct fetch_insn *code = &earg->code[i];

                switch (code->op) {
                case FETCH_OP_ARG:
                        val = regs_get_kernel_argument(regs, code->param);
                        break;
                case FETCH_OP_ST_EDATA:
                        *(unsigned long *)((unsigned long)edata + code->offset) = val;
                        break;
                case FETCH_OP_END:
                        goto end;
                default:
                        break;
                }
        }
end:
        return;
}
NOKPROBE_SYMBOL(store_trace_entry_data)
#endif

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

/* Parse $vars. @orig_arg points '$', which syncs to @ctx->offset */
static int parse_probe_vars(char *orig_arg, const struct fetch_type *t,
                            struct fetch_insn **pcode,
                            struct fetch_insn *end,
                            struct traceprobe_parse_context *ctx)
{
        struct fetch_insn *code = *pcode;
        int err = TP_ERR_BAD_VAR;
        char *arg = orig_arg + 1;
        unsigned long param;
        int ret = 0;
        int len;

        if (ctx->flags & TPARG_FL_TEVENT) {
                if (code->data)
                        return -EFAULT;
                ret = parse_trace_event_arg(arg, code, ctx);
                if (!ret)
                        return 0;
                if (strcmp(arg, "comm") == 0 || strcmp(arg, "COMM") == 0) {
                        code->op = FETCH_OP_COMM;
                        return 0;
                }
                /* backward compatibility */
                ctx->offset = 0;
                goto inval;
        }

        if (str_has_prefix(arg, "retval")) {
                if (!(ctx->flags & TPARG_FL_RETURN)) {
                        err = TP_ERR_RETVAL_ON_PROBE;
                        goto inval;
                }
                if (!(ctx->flags & TPARG_FL_KERNEL) ||
                    !IS_ENABLED(CONFIG_PROBE_EVENTS_BTF_ARGS)) {
                        code->op = FETCH_OP_RETVAL;
                        return 0;
                }
                return parse_btf_arg(orig_arg, pcode, end, ctx);
        }

        len = str_has_prefix(arg, "stack");
        if (len) {

                if (arg[len] == '\0') {
                        code->op = FETCH_OP_STACKP;
                        return 0;
                }

                if (isdigit(arg[len])) {
                        ret = kstrtoul(arg + len, 10, &param);
                        if (ret)
                                goto inval;

                        if ((ctx->flags & TPARG_FL_KERNEL) &&
                            param > PARAM_MAX_STACK) {
                                err = TP_ERR_BAD_STACK_NUM;
                                goto inval;
                        }
                        code->op = FETCH_OP_STACK;
                        code->param = (unsigned int)param;
                        return 0;
                }
                goto inval;
        }

        if (strcmp(arg, "comm") == 0 || strcmp(arg, "COMM") == 0) {
                code->op = FETCH_OP_COMM;
                return 0;
        }

#ifdef CONFIG_HAVE_FUNCTION_ARG_ACCESS_API
        len = str_has_prefix(arg, "arg");
        if (len) {
                ret = kstrtoul(arg + len, 10, &param);
                if (ret)
                        goto inval;

                if (!param || param > PARAM_MAX_STACK) {
                        err = TP_ERR_BAD_ARG_NUM;
                        goto inval;
                }
                param--; /* argN starts from 1, but internal arg[N] starts from 0 */

                if (tparg_is_function_entry(ctx->flags)) {
                        code->op = FETCH_OP_ARG;
                        code->param = (unsigned int)param;
                        /*
                         * The tracepoint probe will probe a stub function, and the
                         * first parameter of the stub is a dummy and should be ignored.
                         */
                        if (ctx->flags & TPARG_FL_TPOINT)
                                code->param++;
                } else if (tparg_is_function_return(ctx->flags)) {
                        /* function entry argument access from return probe */
                        ret = __store_entry_arg(ctx->tp, param);
                        if (ret < 0)    /* This error should be an internal error */
                                return ret;

                        code->op = FETCH_OP_EDATA;
                        code->offset = ret;
                } else {
                        err = TP_ERR_NOFENTRY_ARGS;
                        goto inval;
                }
                return 0;
        }
#endif

inval:
        __trace_probe_log_err(ctx->offset, err);
        return -EINVAL;
}

static int str_to_immediate(char *str, unsigned long *imm)
{
        if (isdigit(str[0]))
                return kstrtoul(str, 0, imm);
        else if (str[0] == '-')
                return kstrtol(str, 0, (long *)imm);
        else if (str[0] == '+')
                return kstrtol(str + 1, 0, (long *)imm);
        return -EINVAL;
}

static int __parse_imm_string(char *str, char **pbuf, int offs)
{
        size_t len = strlen(str);

        if (str[len - 1] != '"') {
                trace_probe_log_err(offs + len, IMMSTR_NO_CLOSE);
                return -EINVAL;
        }
        *pbuf = kstrndup(str, len - 1, GFP_KERNEL);
        if (!*pbuf)
                return -ENOMEM;
        return 0;
}

/* Recursive argument parser */
static int
parse_probe_arg(char *arg, const struct fetch_type *type,
                struct fetch_insn **pcode, struct fetch_insn *end,
                struct traceprobe_parse_context *ctx)
{
        struct fetch_insn *code = *pcode;
        unsigned long param;
        int deref = FETCH_OP_DEREF;
        long offset = 0;
        char *tmp;
        int ret = 0;

        switch (arg[0]) {
        case '$':
                ret = parse_probe_vars(arg, type, pcode, end, ctx);
                break;

        case '%':       /* named register */
                if (ctx->flags & (TPARG_FL_TEVENT | TPARG_FL_FPROBE)) {
                        /* eprobe and fprobe do not handle registers */
                        trace_probe_log_err(ctx->offset, BAD_VAR);
                        break;
                }
                ret = regs_query_register_offset(arg + 1);
                if (ret >= 0) {
                        code->op = FETCH_OP_REG;
                        code->param = (unsigned int)ret;
                        ret = 0;
                } else
                        trace_probe_log_err(ctx->offset, BAD_REG_NAME);
                break;

        case '@':       /* memory, file-offset or symbol */
                if (isdigit(arg[1])) {
                        ret = kstrtoul(arg + 1, 0, &param);
                        if (ret) {
                                trace_probe_log_err(ctx->offset, BAD_MEM_ADDR);
                                break;
                        }
                        /* load address */
                        code->op = FETCH_OP_IMM;
                        code->immediate = param;
                } else if (arg[1] == '+') {
                        /* kprobes don't support file offsets */
                        if (ctx->flags & TPARG_FL_KERNEL) {
                                trace_probe_log_err(ctx->offset, FILE_ON_KPROBE);
                                return -EINVAL;
                        }
                        ret = kstrtol(arg + 2, 0, &offset);
                        if (ret) {
                                trace_probe_log_err(ctx->offset, BAD_FILE_OFFS);
                                break;
                        }

                        code->op = FETCH_OP_FOFFS;
                        code->immediate = (unsigned long)offset;  // imm64?
                } else {
                        /* uprobes don't support symbols */
                        if (!(ctx->flags & TPARG_FL_KERNEL)) {
                                trace_probe_log_err(ctx->offset, SYM_ON_UPROBE);
                                return -EINVAL;
                        }
                        /* Preserve symbol for updating */
                        code->op = FETCH_NOP_SYMBOL;
                        code->data = kstrdup(arg + 1, GFP_KERNEL);
                        if (!code->data)
                                return -ENOMEM;
                        if (++code == end) {
                                trace_probe_log_err(ctx->offset, TOO_MANY_OPS);
                                return -EINVAL;
                        }
                        code->op = FETCH_OP_IMM;
                        code->immediate = 0;
                }
                /* These are fetching from memory */
                if (++code == end) {
                        trace_probe_log_err(ctx->offset, TOO_MANY_OPS);
                        return -EINVAL;
                }
                *pcode = code;
                code->op = FETCH_OP_DEREF;
                code->offset = offset;
                break;

        case '+':       /* deref memory */
        case '-':
                if (arg[1] == 'u') {
                        deref = FETCH_OP_UDEREF;
                        arg[1] = arg[0];
                        arg++;
                }
                if (arg[0] == '+')
                        arg++;  /* Skip '+', because kstrtol() rejects it. */
                tmp = strchr(arg, '(');
                if (!tmp) {
                        trace_probe_log_err(ctx->offset, DEREF_NEED_BRACE);
                        return -EINVAL;
                }
                *tmp = '\0';
                ret = kstrtol(arg, 0, &offset);
                if (ret) {
                        trace_probe_log_err(ctx->offset, BAD_DEREF_OFFS);
                        break;
                }
                ctx->offset += (tmp + 1 - arg) + (arg[0] != '-' ? 1 : 0);
                arg = tmp + 1;
                tmp = strrchr(arg, ')');
                if (!tmp) {
                        trace_probe_log_err(ctx->offset + strlen(arg),
                                            DEREF_OPEN_BRACE);
                        return -EINVAL;
                } else {
                        const struct fetch_type *t2 = find_fetch_type(NULL, ctx->flags);
                        int cur_offs = ctx->offset;

                        *tmp = '\0';
                        ret = parse_probe_arg(arg, t2, &code, end, ctx);
                        if (ret)
                                break;
                        ctx->offset = cur_offs;
                        if (code->op == FETCH_OP_COMM ||
                            code->op == FETCH_OP_DATA) {
                                trace_probe_log_err(ctx->offset, COMM_CANT_DEREF);
                                return -EINVAL;
                        }
                        if (++code == end) {
                                trace_probe_log_err(ctx->offset, TOO_MANY_OPS);
                                return -EINVAL;
                        }
                        *pcode = code;

                        code->op = deref;
                        code->offset = offset;
                        /* Reset the last type if used */
                        ctx->last_type = NULL;
                }
                break;
        case '\\':      /* Immediate value */
                if (arg[1] == '"') {    /* Immediate string */
                        ret = __parse_imm_string(arg + 2, &tmp, ctx->offset + 2);
                        if (ret)
                                break;
                        code->op = FETCH_OP_DATA;
                        code->data = tmp;
                } else {
                        ret = str_to_immediate(arg + 1, &code->immediate);
                        if (ret)
                                trace_probe_log_err(ctx->offset + 1, BAD_IMM);
                        else
                                code->op = FETCH_OP_IMM;
                }
                break;
        default:
                if (isalpha(arg[0]) || arg[0] == '_') { /* BTF variable */
                        if (!tparg_is_function_entry(ctx->flags) &&
                            !tparg_is_function_return(ctx->flags)) {
                                trace_probe_log_err(ctx->offset, NOSUP_BTFARG);
                                return -EINVAL;
                        }
                        ret = parse_btf_arg(arg, pcode, end, ctx);
                        break;
                }
        }
        if (!ret && code->op == FETCH_OP_NOP) {
                /* Parsed, but do not find fetch method */
                trace_probe_log_err(ctx->offset, BAD_FETCH_ARG);
                ret = -EINVAL;
        }
        return ret;
}

/* 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_insn **pcode)
{
        struct fetch_insn *code = *pcode;
        unsigned long bw, bo;
        char *tail;

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

        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;
        code++;
        if (code->op != FETCH_OP_NOP)
                return -EINVAL;
        *pcode = code;

        code->op = FETCH_OP_MOD_BF;
        code->lshift = BYTES_TO_BITS(t->size) - (bw + bo);
        code->rshift = BYTES_TO_BITS(t->size) - bw;
        code->basesize = t->size;

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

/* Split type part from @arg and return it. */
static char *parse_probe_arg_type(char *arg, struct probe_arg *parg,
                                  struct traceprobe_parse_context *ctx)
{
        char *t = NULL, *t2, *t3;
        int offs;

        t = strchr(arg, ':');
        if (t) {
                *t++ = '\0';
                t2 = strchr(t, '[');
                if (t2) {
                        *t2++ = '\0';
                        t3 = strchr(t2, ']');
                        if (!t3) {
                                offs = t2 + strlen(t2) - arg;

                                trace_probe_log_err(ctx->offset + offs,
                                                    ARRAY_NO_CLOSE);
                                return ERR_PTR(-EINVAL);
                        } else if (t3[1] != '\0') {
                                trace_probe_log_err(ctx->offset + t3 + 1 - arg,
                                                    BAD_ARRAY_SUFFIX);
                                return ERR_PTR(-EINVAL);
                        }
                        *t3 = '\0';
                        if (kstrtouint(t2, 0, &parg->count) || !parg->count) {
                                trace_probe_log_err(ctx->offset + t2 - arg,
                                                    BAD_ARRAY_NUM);
                                return ERR_PTR(-EINVAL);
                        }
                        if (parg->count > MAX_ARRAY_LEN) {
                                trace_probe_log_err(ctx->offset + t2 - arg,
                                                    ARRAY_TOO_BIG);
                                return ERR_PTR(-EINVAL);
                        }
                }
        }
        offs = t ? t - arg : 0;

        /*
         * Since $comm and immediate string can not be dereferenced,
         * we can find those by strcmp. But ignore for eprobes.
         */
        if (!(ctx->flags & TPARG_FL_TEVENT) &&
            (strcmp(arg, "$comm") == 0 || strcmp(arg, "$COMM") == 0 ||
             strncmp(arg, "\\\"", 2) == 0)) {
                /* The type of $comm must be "string", and not an array type. */
                if (parg->count || (t && strcmp(t, "string"))) {
                        trace_probe_log_err(ctx->offset + offs, NEED_STRING_TYPE);
                        return ERR_PTR(-EINVAL);
                }
                parg->type = find_fetch_type("string", ctx->flags);
        } else
                parg->type = find_fetch_type(t, ctx->flags);

        if (!parg->type) {
                trace_probe_log_err(ctx->offset + offs, BAD_TYPE);
                return ERR_PTR(-EINVAL);
        }

        return t;
}

/* After parsing, adjust the fetch_insn according to the probe_arg */
static int finalize_fetch_insn(struct fetch_insn *code,
                               struct probe_arg *parg,
                               char *type,
                               int type_offset,
                               struct traceprobe_parse_context *ctx)
{
        struct fetch_insn *scode;
        int ret;

        /* Store operation */
        if (parg->type->is_string) {
                /* Check bad combination of the type and the last fetch_insn. */
                if (!strcmp(parg->type->name, "symstr")) {
                        if (code->op != FETCH_OP_REG && code->op != FETCH_OP_STACK &&
                            code->op != FETCH_OP_RETVAL && code->op != FETCH_OP_ARG &&
                            code->op != FETCH_OP_DEREF && code->op != FETCH_OP_TP_ARG) {
                                trace_probe_log_err(ctx->offset + type_offset,
                                                    BAD_SYMSTRING);
                                return -EINVAL;
                        }
                } else {
                        if (code->op != FETCH_OP_DEREF && code->op != FETCH_OP_UDEREF &&
                            code->op != FETCH_OP_IMM && code->op != FETCH_OP_COMM &&
                            code->op != FETCH_OP_DATA && code->op != FETCH_OP_TP_ARG) {
                                trace_probe_log_err(ctx->offset + type_offset,
                                                    BAD_STRING);
                                return -EINVAL;
                        }
                }

                if (!strcmp(parg->type->name, "symstr") ||
                    (code->op == FETCH_OP_IMM || code->op == FETCH_OP_COMM ||
                     code->op == FETCH_OP_DATA) || code->op == FETCH_OP_TP_ARG ||
                     parg->count) {
                        /*
                         * IMM, DATA and COMM is pointing actual address, those
                         * must be kept, and if parg->count != 0, this is an
                         * array of string pointers instead of string address
                         * itself.
                         * For the symstr, it doesn't need to dereference, thus
                         * it just get the value.
                         */
                        code++;
                        if (code->op != FETCH_OP_NOP) {
                                trace_probe_log_err(ctx->offset, TOO_MANY_OPS);
                                return -EINVAL;
                        }
                }

                /* If op == DEREF, replace it with STRING */
                if (!strcmp(parg->type->name, "ustring") ||
                    code->op == FETCH_OP_UDEREF)
                        code->op = FETCH_OP_ST_USTRING;
                else if (!strcmp(parg->type->name, "symstr"))
                        code->op = FETCH_OP_ST_SYMSTR;
                else
                        code->op = FETCH_OP_ST_STRING;
                code->size = parg->type->size;
                parg->dynamic = true;
        } else if (code->op == FETCH_OP_DEREF) {
                code->op = FETCH_OP_ST_MEM;
                code->size = parg->type->size;
        } else if (code->op == FETCH_OP_UDEREF) {
                code->op = FETCH_OP_ST_UMEM;
                code->size = parg->type->size;
        } else {
                code++;
                if (code->op != FETCH_OP_NOP) {
                        trace_probe_log_err(ctx->offset, TOO_MANY_OPS);
                        return -E2BIG;
                }
                code->op = FETCH_OP_ST_RAW;
                code->size = parg->type->size;
        }

        /* Save storing fetch_insn. */
        scode = code;

        /* Modify operation */
        if (type != NULL) {
                /* Bitfield needs a special fetch_insn. */
                ret = __parse_bitfield_probe_arg(type, parg->type, &code);
                if (ret) {
                        trace_probe_log_err(ctx->offset + type_offset, BAD_BITFIELD);
                        return ret;
                }
        } else if (IS_ENABLED(CONFIG_PROBE_EVENTS_BTF_ARGS) &&
                   ctx->last_type) {
                /* If user not specified the type, try parsing BTF bitfield. */
                ret = parse_btf_bitfield(&code, ctx);
                if (ret)
                        return ret;
        }

        /* Loop(Array) operation */
        if (parg->count) {
                if (scode->op != FETCH_OP_ST_MEM &&
                    scode->op != FETCH_OP_ST_STRING &&
                    scode->op != FETCH_OP_ST_USTRING) {
                        trace_probe_log_err(ctx->offset + type_offset, BAD_STRING);
                        return -EINVAL;
                }
                code++;
                if (code->op != FETCH_OP_NOP) {
                        trace_probe_log_err(ctx->offset, TOO_MANY_OPS);
                        return -E2BIG;
                }
                code->op = FETCH_OP_LP_ARRAY;
                code->param = parg->count;
        }

        /* Finalize the fetch_insn array. */
        code++;
        code->op = FETCH_OP_END;

        return 0;
}

/* String length checking wrapper */
static int traceprobe_parse_probe_arg_body(const char *argv, ssize_t *size,
                                           struct probe_arg *parg,
                                           struct traceprobe_parse_context *ctx)
{
        struct fetch_insn *code, *tmp = NULL;
        char *type, *arg __free(kfree) = NULL;
        int ret, len;

        len = strlen(argv);
        if (len > MAX_ARGSTR_LEN) {
                trace_probe_log_err(ctx->offset, ARG_TOO_LONG);
                return -E2BIG;
        } else if (len == 0) {
                trace_probe_log_err(ctx->offset, NO_ARG_BODY);
                return -EINVAL;
        }

        arg = kstrdup(argv, GFP_KERNEL);
        if (!arg)
                return -ENOMEM;

        parg->comm = kstrdup(arg, GFP_KERNEL);
        if (!parg->comm)
                return -ENOMEM;

        type = parse_probe_arg_type(arg, parg, ctx);
        if (IS_ERR(type))
                return PTR_ERR(type);

        code = tmp = kzalloc_objs(*code, FETCH_INSN_MAX);
        if (!code)
                return -ENOMEM;
        code[FETCH_INSN_MAX - 1].op = FETCH_OP_END;

        ctx->last_type = NULL;
        ret = parse_probe_arg(arg, parg->type, &code, &code[FETCH_INSN_MAX - 1],
                              ctx);
        if (ret < 0)
                goto fail;

        /* Update storing type if BTF is available */
        if (IS_ENABLED(CONFIG_PROBE_EVENTS_BTF_ARGS) &&
            ctx->last_type) {
                if (!type) {
                        parg->type = find_fetch_type_from_btf_type(ctx);
                } else if (strstr(type, "string")) {
                        ret = check_prepare_btf_string_fetch(type, &code, ctx);
                        if (ret)
                                goto fail;
                }
        }
        parg->offset = *size;
        *size += parg->type->size * (parg->count ?: 1);

        if (parg->count) {
                len = strlen(parg->type->fmttype) + 6;
                parg->fmt = kmalloc(len, GFP_KERNEL);
                if (!parg->fmt) {
                        ret = -ENOMEM;
                        goto fail;
                }
                snprintf(parg->fmt, len, "%s[%d]", parg->type->fmttype,
                         parg->count);
        }

        ret = finalize_fetch_insn(code, parg, type, type ? type - arg : 0, ctx);
        if (ret < 0)
                goto fail;

        for (; code < tmp + FETCH_INSN_MAX; code++)
                if (code->op == FETCH_OP_END)
                        break;
        /* Shrink down the code buffer */
        parg->code = kzalloc_objs(*code, code - tmp + 1);
        if (!parg->code)
                ret = -ENOMEM;
        else
                memcpy(parg->code, tmp, sizeof(*code) * (code - tmp + 1));

fail:
        if (ret < 0) {
                for (code = tmp; code < tmp + FETCH_INSN_MAX; code++)
                        if (code->op == FETCH_NOP_SYMBOL ||
                            code->op == FETCH_OP_DATA)
                                kfree(code->data);
        }
        kfree(tmp);

        return ret;
}

/* Return 1 if name is reserved or already used by another argument */
static 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;
}

static char *generate_probe_arg_name(const char *arg, int idx)
{
        char *name = NULL;
        const char *end;

        /*
         * If argument name is omitted, try arg as a name (BTF variable)
         * or "argN".
         */
        if (IS_ENABLED(CONFIG_PROBE_EVENTS_BTF_ARGS)) {
                end = strchr(arg, ':');
                if (!end)
                        end = arg + strlen(arg);

                name = kmemdup_nul(arg, end - arg, GFP_KERNEL);
                if (!name || !is_good_name(name)) {
                        kfree(name);
                        name = NULL;
                }
        }

        if (!name)
                name = kasprintf(GFP_KERNEL, "arg%d", idx + 1);

        return name;
}

int traceprobe_parse_probe_arg(struct trace_probe *tp, int i, const char *arg,
                               struct traceprobe_parse_context *ctx)
{
        struct probe_arg *parg = &tp->args[i];
        const char *body;

        ctx->tp = tp;
        body = strchr(arg, '=');
        if (body) {
                if (body - arg > MAX_ARG_NAME_LEN) {
                        trace_probe_log_err(0, ARG_NAME_TOO_LONG);
                        return -EINVAL;
                } else if (body == arg) {
                        trace_probe_log_err(0, NO_ARG_NAME);
                        return -EINVAL;
                }
                parg->name = kmemdup_nul(arg, body - arg, GFP_KERNEL);
                body++;
        } else {
                parg->name = generate_probe_arg_name(arg, i);
                body = arg;
        }
        if (!parg->name)
                return -ENOMEM;

        if (!is_good_name(parg->name)) {
                trace_probe_log_err(0, BAD_ARG_NAME);
                return -EINVAL;
        }
        if (traceprobe_conflict_field_name(parg->name, tp->args, i)) {
                trace_probe_log_err(0, USED_ARG_NAME);
                return -EINVAL;
        }
        ctx->offset = body - arg;
        /* Parse fetch argument */
        return traceprobe_parse_probe_arg_body(body, &tp->size, parg, ctx);
}

void traceprobe_free_probe_arg(struct probe_arg *arg)
{
        struct fetch_insn *code = arg->code;

        while (code && code->op != FETCH_OP_END) {
                if (code->op == FETCH_NOP_SYMBOL ||
                    code->op == FETCH_OP_DATA)
                        kfree(code->data);
                code++;
        }
        kfree(arg->code);
        kfree(arg->name);
        kfree(arg->comm);
        kfree(arg->fmt);
}

static int argv_has_var_arg(int argc, const char *argv[], int *args_idx,
                            struct traceprobe_parse_context *ctx)
{
        int i, found = 0;

        for (i = 0; i < argc; i++)
                if (str_has_prefix(argv[i], "$arg")) {
                        trace_probe_log_set_index(i + 2);

                        if (!tparg_is_function_entry(ctx->flags) &&
                            !tparg_is_function_return(ctx->flags)) {
                                trace_probe_log_err(0, NOFENTRY_ARGS);
                                return -EINVAL;
                        }

                        if (isdigit(argv[i][4])) {
                                found = 1;
                                continue;
                        }

                        if (argv[i][4] != '*') {
                                trace_probe_log_err(0, BAD_VAR);
                                return -EINVAL;
                        }

                        if (*args_idx >= 0 && *args_idx < argc) {
                                trace_probe_log_err(0, DOUBLE_ARGS);
                                return -EINVAL;
                        }
                        found = 1;
                        *args_idx = i;
                }

        return found;
}

static int sprint_nth_btf_arg(int idx, const char *type,
                              char *buf, int bufsize,
                              struct traceprobe_parse_context *ctx)
{
        const char *name;
        int ret;

        if (idx >= ctx->nr_params) {
                trace_probe_log_err(0, NO_BTFARG);
                return -ENOENT;
        }
        name = btf_name_by_offset(ctx->btf, ctx->params[idx].name_off);
        if (!name) {
                trace_probe_log_err(0, NO_BTF_ENTRY);
                return -ENOENT;
        }
        ret = snprintf(buf, bufsize, "%s%s", name, type);
        if (ret >= bufsize) {
                trace_probe_log_err(0, ARGS_2LONG);
                return -E2BIG;
        }
        return ret;
}

/* Return new_argv which must be freed after use */
const char **traceprobe_expand_meta_args(int argc, const char *argv[],
                                         int *new_argc, char *buf, int bufsize,
                                         struct traceprobe_parse_context *ctx)
{
        const struct btf_param *params = NULL;
        int i, j, n, used, ret, args_idx = -1;
        const char **new_argv __free(kfree) = NULL;

        ret = argv_has_var_arg(argc, argv, &args_idx, ctx);
        if (ret < 0)
                return ERR_PTR(ret);

        if (!ret) {
                *new_argc = argc;
                return NULL;
        }

        ret = query_btf_context(ctx);
        if (ret < 0 || ctx->nr_params == 0) {
                if (args_idx != -1) {
                        /* $arg* requires BTF info */
                        trace_probe_log_err(0, NOSUP_BTFARG);
                        return (const char **)params;
                }
                *new_argc = argc;
                return NULL;
        }

        if (args_idx >= 0)
                *new_argc = argc + ctx->nr_params - 1;
        else
                *new_argc = argc;

        new_argv = kcalloc(*new_argc, sizeof(char *), GFP_KERNEL);
        if (!new_argv)
                return ERR_PTR(-ENOMEM);

        used = 0;
        for (i = 0, j = 0; i < argc; i++) {
                trace_probe_log_set_index(i + 2);
                if (i == args_idx) {
                        for (n = 0; n < ctx->nr_params; n++) {
                                ret = sprint_nth_btf_arg(n, "", buf + used,
                                                         bufsize - used, ctx);
                                if (ret < 0)
                                        return ERR_PTR(ret);

                                new_argv[j++] = buf + used;
                                used += ret + 1;
                        }
                        continue;
                }

                if (str_has_prefix(argv[i], "$arg")) {
                        char *type = NULL;

                        n = simple_strtoul(argv[i] + 4, &type, 10);
                        if (type && !(*type == ':' || *type == '\0')) {
                                trace_probe_log_err(0, BAD_VAR);
                                return ERR_PTR(-ENOENT);
                        }
                        /* Note: $argN starts from $arg1 */
                        ret = sprint_nth_btf_arg(n - 1, type, buf + used,
                                                 bufsize - used, ctx);
                        if (ret < 0)
                                return ERR_PTR(ret);
                        new_argv[j++] = buf + used;
                        used += ret + 1;
                } else
                        new_argv[j++] = argv[i];
        }

        return_ptr(new_argv);
}

/* @buf: *buf must be equal to NULL. Caller must to free *buf */
int traceprobe_expand_dentry_args(int argc, const char *argv[], char **buf)
{
        int i, used, ret;
        const int bufsize = MAX_DENTRY_ARGS_LEN;
        char *tmpbuf __free(kfree) = NULL;

        if (*buf)
                return -EINVAL;

        used = 0;
        for (i = 0; i < argc; i++) {
                char *tmp __free(kfree) = NULL;
                char *equal;
                size_t arg_len;

                if (!glob_match("*:%p[dD]", argv[i]))
                        continue;

                if (!tmpbuf) {
                        tmpbuf = kmalloc(bufsize, GFP_KERNEL);
                        if (!tmpbuf)
                                return -ENOMEM;
                }

                tmp = kstrdup(argv[i], GFP_KERNEL);
                if (!tmp)
                        return -ENOMEM;

                equal = strchr(tmp, '=');
                if (equal)
                        *equal = '\0';
                arg_len = strlen(argv[i]);
                tmp[arg_len - 4] = '\0';
                if (argv[i][arg_len - 1] == 'd')
                        ret = snprintf(tmpbuf + used, bufsize - used,
                                       "%s%s+0x0(+0x%zx(%s)):string",
                                       equal ? tmp : "", equal ? "=" : "",
                                       offsetof(struct dentry, d_name.name),
                                       equal ? equal + 1 : tmp);
                else
                        ret = snprintf(tmpbuf + used, bufsize - used,
                                       "%s%s+0x0(+0x%zx(+0x%zx(%s))):string",
                                       equal ? tmp : "", equal ? "=" : "",
                                       offsetof(struct dentry, d_name.name),
                                       offsetof(struct file, f_path.dentry),
                                       equal ? equal + 1 : tmp);

                if (ret >= bufsize - used)
                        return -ENOMEM;
                argv[i] = tmpbuf + used;
                used += ret + 1;
        }

        *buf = no_free_ptr(tmpbuf);
        return 0;
}

void traceprobe_finish_parse(struct traceprobe_parse_context *ctx)
{
        clear_btf_context(ctx);
}

int traceprobe_update_arg(struct probe_arg *arg)
{
        struct fetch_insn *code = arg->code;
        long offset;
        char *tmp;
        char c;
        int ret = 0;

        while (code && code->op != FETCH_OP_END) {
                if (code->op == FETCH_NOP_SYMBOL) {
                        if (code[1].op != FETCH_OP_IMM)
                                return -EINVAL;

                        tmp = strpbrk(code->data, "+-");
                        if (tmp)
                                c = *tmp;
                        ret = traceprobe_split_symbol_offset(code->data,
                                                             &offset);
                        if (ret)
                                return ret;

                        code[1].immediate =
                                (unsigned long)kallsyms_lookup_name(code->data);
                        if (tmp)
                                *tmp = c;
                        if (!code[1].immediate)
                                return -ENOENT;
                        code[1].immediate += offset;
                }
                code++;
        }
        return 0;
}

/* When len=0, we just calculate the needed length */
#define LEN_OR_ZERO (len ? len - pos : 0)
static int __set_print_fmt(struct trace_probe *tp, char *buf, int len,
                           enum probe_print_type ptype)
{
        struct probe_arg *parg;
        int i, j;
        int pos = 0;
        const char *fmt, *arg;

        switch (ptype) {
        case PROBE_PRINT_NORMAL:
                fmt = "(%lx)";
                arg = ", REC->" FIELD_STRING_IP;
                break;
        case PROBE_PRINT_RETURN:
                fmt = "(%lx <- %lx)";
                arg = ", REC->" FIELD_STRING_FUNC ", REC->" FIELD_STRING_RETIP;
                break;
        case PROBE_PRINT_EVENT:
                fmt = "";
                arg = "";
                break;
        default:
                WARN_ON_ONCE(1);
                return 0;
        }

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

        for (i = 0; i < tp->nr_args; i++) {
                parg = tp->args + i;
                pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=", parg->name);
                if (parg->count) {
                        pos += snprintf(buf + pos, LEN_OR_ZERO, "{%s",
                                        parg->type->fmt);
                        for (j = 1; j < parg->count; j++)
                                pos += snprintf(buf + pos, LEN_OR_ZERO, ",%s",
                                                parg->type->fmt);
                        pos += snprintf(buf + pos, LEN_OR_ZERO, "}");
                } else
                        pos += snprintf(buf + pos, LEN_OR_ZERO, "%s",
                                        parg->type->fmt);
        }

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

        for (i = 0; i < tp->nr_args; i++) {
                parg = tp->args + i;
                if (parg->count) {
                        if (parg->type->is_string)
                                fmt = ", __get_str(%s[%d])";
                        else
                                fmt = ", REC->%s[%d]";
                        for (j = 0; j < parg->count; j++)
                                pos += snprintf(buf + pos, LEN_OR_ZERO,
                                                fmt, parg->name, j);
                } else {
                        if (parg->type->is_string)
                                fmt = ", __get_str(%s)";
                        else
                                fmt = ", REC->%s";
                        pos += snprintf(buf + pos, LEN_OR_ZERO,
                                        fmt, parg->name);
                }
        }

        /* return the length of print_fmt */
        return pos;
}
#undef LEN_OR_ZERO

int traceprobe_set_print_fmt(struct trace_probe *tp, enum probe_print_type ptype)
{
        struct trace_event_call *call = trace_probe_event_call(tp);
        int len;
        char *print_fmt;

        /* First: called with 0 length to calculate the needed length */
        len = __set_print_fmt(tp, NULL, 0, ptype);
        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, ptype);
        call->print_fmt = print_fmt;

        return 0;
}

int traceprobe_define_arg_fields(struct trace_event_call *event_call,
                                 size_t offset, struct trace_probe *tp)
{
        int ret, i;

        /* Set argument names as fields */
        for (i = 0; i < tp->nr_args; i++) {
                struct probe_arg *parg = &tp->args[i];
                const char *fmt = parg->type->fmttype;
                int size = parg->type->size;

                if (parg->fmt)
                        fmt = parg->fmt;
                if (parg->count)
                        size *= parg->count;
                ret = trace_define_field(event_call, fmt, parg->name,
                                         offset + parg->offset, size,
                                         parg->type->is_signed,
                                         FILTER_OTHER);
                if (ret)
                        return ret;
        }
        return 0;
}

static void trace_probe_event_free(struct trace_probe_event *tpe)
{
        kfree(tpe->class.system);
        kfree(tpe->call.name);
        kfree(tpe->call.print_fmt);
        kfree(tpe);
}

int trace_probe_append(struct trace_probe *tp, struct trace_probe *to)
{
        if (trace_probe_has_sibling(tp))
                return -EBUSY;

        list_del_init(&tp->list);
        trace_probe_event_free(tp->event);

        tp->event = to->event;
        list_add_tail(&tp->list, trace_probe_probe_list(to));

        return 0;
}

void trace_probe_unlink(struct trace_probe *tp)
{
        list_del_init(&tp->list);
        if (list_empty(trace_probe_probe_list(tp)))
                trace_probe_event_free(tp->event);
        tp->event = NULL;
}

void trace_probe_cleanup(struct trace_probe *tp)
{
        int i;

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

        if (tp->entry_arg) {
                kfree(tp->entry_arg->code);
                kfree(tp->entry_arg);
                tp->entry_arg = NULL;
        }

        if (tp->event)
                trace_probe_unlink(tp);
}

int trace_probe_init(struct trace_probe *tp, const char *event,
                     const char *group, bool alloc_filter, int nargs)
{
        struct trace_event_call *call;
        size_t size = sizeof(struct trace_probe_event);
        int ret = 0;

        if (!event || !group)
                return -EINVAL;

        if (alloc_filter)
                size += sizeof(struct trace_uprobe_filter);

        tp->event = kzalloc(size, GFP_KERNEL);
        if (!tp->event)
                return -ENOMEM;

        INIT_LIST_HEAD(&tp->event->files);
        INIT_LIST_HEAD(&tp->event->class.fields);
        INIT_LIST_HEAD(&tp->event->probes);
        INIT_LIST_HEAD(&tp->list);
        list_add(&tp->list, &tp->event->probes);

        call = trace_probe_event_call(tp);
        call->class = &tp->event->class;
        call->name = kstrdup(event, GFP_KERNEL);
        if (!call->name) {
                ret = -ENOMEM;
                goto error;
        }

        tp->event->class.system = kstrdup(group, GFP_KERNEL);
        if (!tp->event->class.system) {
                ret = -ENOMEM;
                goto error;
        }

        tp->nr_args = nargs;
        /* Make sure pointers in args[] are NULL */
        if (nargs)
                memset(tp->args, 0, sizeof(tp->args[0]) * nargs);

        return 0;

error:
        trace_probe_cleanup(tp);
        return ret;
}

static struct trace_event_call *
find_trace_event_call(const char *system, const char *event_name)
{
        struct trace_event_call *tp_event;
        const char *name;

        list_for_each_entry(tp_event, &ftrace_events, list) {
                if (!tp_event->class->system ||
                    strcmp(system, tp_event->class->system))
                        continue;
                name = trace_event_name(tp_event);
                if (!name || strcmp(event_name, name))
                        continue;
                return tp_event;
        }

        return NULL;
}

int trace_probe_register_event_call(struct trace_probe *tp)
{
        struct trace_event_call *call = trace_probe_event_call(tp);
        int ret;

        lockdep_assert_held(&event_mutex);

        if (find_trace_event_call(trace_probe_group_name(tp),
                                  trace_probe_name(tp)))
                return -EEXIST;

        ret = register_trace_event(&call->event);
        if (!ret)
                return -ENODEV;

        ret = trace_add_event_call(call);
        if (ret)
                unregister_trace_event(&call->event);

        return ret;
}

int trace_probe_add_file(struct trace_probe *tp, struct trace_event_file *file)
{
        struct event_file_link *link;

        link = kmalloc_obj(*link);
        if (!link)
                return -ENOMEM;

        link->file = file;
        INIT_LIST_HEAD(&link->list);
        list_add_tail_rcu(&link->list, &tp->event->files);
        trace_probe_set_flag(tp, TP_FLAG_TRACE);
        return 0;
}

struct event_file_link *trace_probe_get_file_link(struct trace_probe *tp,
                                                  struct trace_event_file *file)
{
        struct event_file_link *link;

        trace_probe_for_each_link(link, tp) {
                if (link->file == file)
                        return link;
        }

        return NULL;
}

int trace_probe_remove_file(struct trace_probe *tp,
                            struct trace_event_file *file)
{
        struct event_file_link *link;

        link = trace_probe_get_file_link(tp, file);
        if (!link)
                return -ENOENT;

        list_del_rcu(&link->list);
        kvfree_rcu_mightsleep(link);

        if (list_empty(&tp->event->files))
                trace_probe_clear_flag(tp, TP_FLAG_TRACE);

        return 0;
}

/*
 * Return the smallest index of different type argument (start from 1).
 * If all argument types and name are same, return 0.
 */
int trace_probe_compare_arg_type(struct trace_probe *a, struct trace_probe *b)
{
        int i;

        /* In case of more arguments */
        if (a->nr_args < b->nr_args)
                return a->nr_args + 1;
        if (a->nr_args > b->nr_args)
                return b->nr_args + 1;

        for (i = 0; i < a->nr_args; i++) {
                if ((b->nr_args <= i) ||
                    ((a->args[i].type != b->args[i].type) ||
                     (a->args[i].count != b->args[i].count) ||
                     strcmp(a->args[i].name, b->args[i].name)))
                        return i + 1;
        }

        return 0;
}

bool trace_probe_match_command_args(struct trace_probe *tp,
                                    int argc, const char **argv)
{
        char buf[MAX_ARGSTR_LEN + 1];
        int i;

        if (tp->nr_args < argc)
                return false;

        for (i = 0; i < argc; i++) {
                snprintf(buf, sizeof(buf), "%s=%s",
                         tp->args[i].name, tp->args[i].comm);
                if (strcmp(buf, argv[i]))
                        return false;
        }
        return true;
}

int trace_probe_create(const char *raw_command, int (*createfn)(int, const char **))
{
        int argc = 0, ret = 0;
        char **argv;

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

        if (argc)
                ret = createfn(argc, (const char **)argv);

        argv_free(argv);

        return ret;
}

int trace_probe_print_args(struct trace_seq *s, struct probe_arg *args, int nr_args,
                 u8 *data, void *field)
{
        void *p;
        int i, j;

        for (i = 0; i < nr_args; i++) {
                struct probe_arg *a = args + i;

                trace_seq_printf(s, " %s=", a->name);
                if (likely(!a->count)) {
                        if (!a->type->print(s, data + a->offset, field))
                                return -ENOMEM;
                        continue;
                }
                trace_seq_putc(s, '{');
                p = data + a->offset;
                for (j = 0; j < a->count; j++) {
                        if (!a->type->print(s, p, field))
                                return -ENOMEM;
                        trace_seq_putc(s, j == a->count - 1 ? '}' : ',');
                        p += a->type->size;
                }
        }
        return 0;
}