/* SPDX-License-Identifier: GPL-2.0 */
/* Copyright (c) 2018 Facebook */

#include <uapi/linux/btf.h>
#include <uapi/linux/bpf.h>
#include <uapi/linux/bpf_perf_event.h>
#include <uapi/linux/types.h>
#include <linux/seq_file.h>
#include <linux/compiler.h>
#include <linux/ctype.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/anon_inodes.h>
#include <linux/file.h>
#include <linux/uaccess.h>
#include <linux/kernel.h>
#include <linux/idr.h>
#include <linux/sort.h>
#include <linux/bpf_verifier.h>
#include <linux/btf.h>
#include <linux/btf_ids.h>
#include <linux/skmsg.h>
#include <linux/perf_event.h>
#include <linux/bsearch.h>
#include <linux/btf_ids.h>
#include <net/sock.h>

/* BTF (BPF Type Format) is the meta data format which describes
 * the data types of BPF program/map.  Hence, it basically focus
 * on the C programming language which the modern BPF is primary
 * using.
 *
 * ELF Section:
 * ~~~~~~~~~~~
 * The BTF data is stored under the ".BTF" ELF section
 *
 * struct btf_type:
 * ~~~~~~~~~~~~~~~
 * Each 'struct btf_type' object describes a C data type.
 * Depending on the type it is describing, a 'struct btf_type'
 * object may be followed by more data.  F.e.
 * To describe an array, 'struct btf_type' is followed by
 * 'struct btf_array'.
 *
 * 'struct btf_type' and any extra data following it are
 * 4 bytes aligned.
 *
 * Type section:
 * ~~~~~~~~~~~~~
 * The BTF type section contains a list of 'struct btf_type' objects.
 * Each one describes a C type.  Recall from the above section
 * that a 'struct btf_type' object could be immediately followed by extra
 * data in order to desribe some particular C types.
 *
 * type_id:
 * ~~~~~~~
 * Each btf_type object is identified by a type_id.  The type_id
 * is implicitly implied by the location of the btf_type object in
 * the BTF type section.  The first one has type_id 1.  The second
 * one has type_id 2...etc.  Hence, an earlier btf_type has
 * a smaller type_id.
 *
 * A btf_type object may refer to another btf_type object by using
 * type_id (i.e. the "type" in the "struct btf_type").
 *
 * NOTE that we cannot assume any reference-order.
 * A btf_type object can refer to an earlier btf_type object
 * but it can also refer to a later btf_type object.
 *
 * For example, to describe "const void *".  A btf_type
 * object describing "const" may refer to another btf_type
 * object describing "void *".  This type-reference is done
 * by specifying type_id:
 *
 * [1] CONST (anon) type_id=2
 * [2] PTR (anon) type_id=0
 *
 * The above is the btf_verifier debug log:
 *   - Each line started with "[?]" is a btf_type object
 *   - [?] is the type_id of the btf_type object.
 *   - CONST/PTR is the BTF_KIND_XXX
 *   - "(anon)" is the name of the type.  It just
 *     happens that CONST and PTR has no name.
 *   - type_id=XXX is the 'u32 type' in btf_type
 *
 * NOTE: "void" has type_id 0
 *
 * String section:
 * ~~~~~~~~~~~~~~
 * The BTF string section contains the names used by the type section.
 * Each string is referred by an "offset" from the beginning of the
 * string section.
 *
 * Each string is '\0' terminated.
 *
 * The first character in the string section must be '\0'
 * which is used to mean 'anonymous'. Some btf_type may not
 * have a name.
 */

/* BTF verification:
 *
 * To verify BTF data, two passes are needed.
 *
 * Pass #1
 * ~~~~~~~
 * The first pass is to collect all btf_type objects to
 * an array: "btf->types".
 *
 * Depending on the C type that a btf_type is describing,
 * a btf_type may be followed by extra data.  We don't know
 * how many btf_type is there, and more importantly we don't
 * know where each btf_type is located in the type section.
 *
 * Without knowing the location of each type_id, most verifications
 * cannot be done.  e.g. an earlier btf_type may refer to a later
 * btf_type (recall the "const void *" above), so we cannot
 * check this type-reference in the first pass.
 *
 * In the first pass, it still does some verifications (e.g.
 * checking the name is a valid offset to the string section).
 *
 * Pass #2
 * ~~~~~~~
 * The main focus is to resolve a btf_type that is referring
 * to another type.
 *
 * We have to ensure the referring type:
 * 1) does exist in the BTF (i.e. in btf->types[])
 * 2) does not cause a loop:
 *      struct A {
 *              struct B b;
 *      };
 *
 *      struct B {
 *              struct A a;
 *      };
 *
 * btf_type_needs_resolve() decides if a btf_type needs
 * to be resolved.
 *
 * The needs_resolve type implements the "resolve()" ops which
 * essentially does a DFS and detects backedge.
 *
 * During resolve (or DFS), different C types have different
 * "RESOLVED" conditions.
 *
 * When resolving a BTF_KIND_STRUCT, we need to resolve all its
 * members because a member is always referring to another
 * type.  A struct's member can be treated as "RESOLVED" if
 * it is referring to a BTF_KIND_PTR.  Otherwise, the
 * following valid C struct would be rejected:
 *
 *      struct A {
 *              int m;
 *              struct A *a;
 *      };
 *
 * When resolving a BTF_KIND_PTR, it needs to keep resolving if
 * it is referring to another BTF_KIND_PTR.  Otherwise, we cannot
 * detect a pointer loop, e.g.:
 * BTF_KIND_CONST -> BTF_KIND_PTR -> BTF_KIND_CONST -> BTF_KIND_PTR +
 *                        ^                                         |
 *                        +-----------------------------------------+
 *
 */

#define BITS_PER_U128 (sizeof(u64) * BITS_PER_BYTE * 2)
#define BITS_PER_BYTE_MASK (BITS_PER_BYTE - 1)
#define BITS_PER_BYTE_MASKED(bits) ((bits) & BITS_PER_BYTE_MASK)
#define BITS_ROUNDDOWN_BYTES(bits) ((bits) >> 3)
#define BITS_ROUNDUP_BYTES(bits) \
        (BITS_ROUNDDOWN_BYTES(bits) + !!BITS_PER_BYTE_MASKED(bits))

#define BTF_INFO_MASK 0x8f00ffff
#define BTF_INT_MASK 0x0fffffff
#define BTF_TYPE_ID_VALID(type_id) ((type_id) <= BTF_MAX_TYPE)
#define BTF_STR_OFFSET_VALID(name_off) ((name_off) <= BTF_MAX_NAME_OFFSET)

/* 16MB for 64k structs and each has 16 members and
 * a few MB spaces for the string section.
 * The hard limit is S32_MAX.
 */
#define BTF_MAX_SIZE (16 * 1024 * 1024)

#define for_each_member_from(i, from, struct_type, member)              \
        for (i = from, member = btf_type_member(struct_type) + from;    \
             i < btf_type_vlen(struct_type);                            \
             i++, member++)

#define for_each_vsi_from(i, from, struct_type, member)                         \
        for (i = from, member = btf_type_var_secinfo(struct_type) + from;       \
             i < btf_type_vlen(struct_type);                                    \
             i++, member++)

DEFINE_IDR(btf_idr);
DEFINE_SPINLOCK(btf_idr_lock);

struct btf {
        void *data;
        struct btf_type **types;
        u32 *resolved_ids;
        u32 *resolved_sizes;
        const char *strings;
        void *nohdr_data;
        struct btf_header hdr;
        u32 nr_types;
        u32 types_size;
        u32 data_size;
        refcount_t refcnt;
        u32 id;
        struct rcu_head rcu;
};

enum verifier_phase {
        CHECK_META,
        CHECK_TYPE,
};

struct resolve_vertex {
        const struct btf_type *t;
        u32 type_id;
        u16 next_member;
};

enum visit_state {
        NOT_VISITED,
        VISITED,
        RESOLVED,
};

enum resolve_mode {
        RESOLVE_TBD,    /* To Be Determined */
        RESOLVE_PTR,    /* Resolving for Pointer */
        RESOLVE_STRUCT_OR_ARRAY,        /* Resolving for struct/union
                                         * or array
                                         */
};

#define MAX_RESOLVE_DEPTH 32

struct btf_sec_info {
        u32 off;
        u32 len;
};

struct btf_verifier_env {
        struct btf *btf;
        u8 *visit_states;
        struct resolve_vertex stack[MAX_RESOLVE_DEPTH];
        struct bpf_verifier_log log;
        u32 log_type_id;
        u32 top_stack;
        enum verifier_phase phase;
        enum resolve_mode resolve_mode;
};

static const char * const btf_kind_str[NR_BTF_KINDS] = {
        [BTF_KIND_UNKN]         = "UNKNOWN",
        [BTF_KIND_INT]          = "INT",
        [BTF_KIND_PTR]          = "PTR",
        [BTF_KIND_ARRAY]        = "ARRAY",
        [BTF_KIND_STRUCT]       = "STRUCT",
        [BTF_KIND_UNION]        = "UNION",
        [BTF_KIND_ENUM]         = "ENUM",
        [BTF_KIND_FWD]          = "FWD",
        [BTF_KIND_TYPEDEF]      = "TYPEDEF",
        [BTF_KIND_VOLATILE]     = "VOLATILE",
        [BTF_KIND_CONST]        = "CONST",
        [BTF_KIND_RESTRICT]     = "RESTRICT",
        [BTF_KIND_FUNC]         = "FUNC",
        [BTF_KIND_FUNC_PROTO]   = "FUNC_PROTO",
        [BTF_KIND_VAR]          = "VAR",
        [BTF_KIND_DATASEC]      = "DATASEC",
};

static const char *btf_type_str(const struct btf_type *t)
{
        return btf_kind_str[BTF_INFO_KIND(t->info)];
}

/* Chunk size we use in safe copy of data to be shown. */
#define BTF_SHOW_OBJ_SAFE_SIZE          32

/*
 * This is the maximum size of a base type value (equivalent to a
 * 128-bit int); if we are at the end of our safe buffer and have
 * less than 16 bytes space we can't be assured of being able
 * to copy the next type safely, so in such cases we will initiate
 * a new copy.
 */
#define BTF_SHOW_OBJ_BASE_TYPE_SIZE     16

/* Type name size */
#define BTF_SHOW_NAME_SIZE              80

/*
 * Common data to all BTF show operations. Private show functions can add
 * their own data to a structure containing a struct btf_show and consult it
 * in the show callback.  See btf_type_show() below.
 *
 * One challenge with showing nested data is we want to skip 0-valued
 * data, but in order to figure out whether a nested object is all zeros
 * we need to walk through it.  As a result, we need to make two passes
 * when handling structs, unions and arrays; the first path simply looks
 * for nonzero data, while the second actually does the display.  The first
 * pass is signalled by show->state.depth_check being set, and if we
 * encounter a non-zero value we set show->state.depth_to_show to
 * the depth at which we encountered it.  When we have completed the
 * first pass, we will know if anything needs to be displayed if
 * depth_to_show > depth.  See btf_[struct,array]_show() for the
 * implementation of this.
 *
 * Another problem is we want to ensure the data for display is safe to
 * access.  To support this, the anonymous "struct {} obj" tracks the data
 * object and our safe copy of it.  We copy portions of the data needed
 * to the object "copy" buffer, but because its size is limited to
 * BTF_SHOW_OBJ_COPY_LEN bytes, multiple copies may be required as we
 * traverse larger objects for display.
 *
 * The various data type show functions all start with a call to
 * btf_show_start_type() which returns a pointer to the safe copy
 * of the data needed (or if BTF_SHOW_UNSAFE is specified, to the
 * raw data itself).  btf_show_obj_safe() is responsible for
 * using copy_from_kernel_nofault() to update the safe data if necessary
 * as we traverse the object's data.  skbuff-like semantics are
 * used:
 *
 * - obj.head points to the start of the toplevel object for display
 * - obj.size is the size of the toplevel object
 * - obj.data points to the current point in the original data at
 *   which our safe data starts.  obj.data will advance as we copy
 *   portions of the data.
 *
 * In most cases a single copy will suffice, but larger data structures
 * such as "struct task_struct" will require many copies.  The logic in
 * btf_show_obj_safe() handles the logic that determines if a new
 * copy_from_kernel_nofault() is needed.
 */
struct btf_show {
        u64 flags;
        void *target;   /* target of show operation (seq file, buffer) */
        void (*showfn)(struct btf_show *show, const char *fmt, va_list args);
        const struct btf *btf;
        /* below are used during iteration */
        struct {
                u8 depth;
                u8 depth_to_show;
                u8 depth_check;
                u8 array_member:1,
                   array_terminated:1;
                u16 array_encoding;
                u32 type_id;
                int status;                     /* non-zero for error */
                const struct btf_type *type;
                const struct btf_member *member;
                char name[BTF_SHOW_NAME_SIZE];  /* space for member name/type */
        } state;
        struct {
                u32 size;
                void *head;
                void *data;
                u8 safe[BTF_SHOW_OBJ_SAFE_SIZE];
        } obj;
};

struct btf_kind_operations {
        s32 (*check_meta)(struct btf_verifier_env *env,
                          const struct btf_type *t,
                          u32 meta_left);
        int (*resolve)(struct btf_verifier_env *env,
                       const struct resolve_vertex *v);
        int (*check_member)(struct btf_verifier_env *env,
                            const struct btf_type *struct_type,
                            const struct btf_member *member,
                            const struct btf_type *member_type);
        int (*check_kflag_member)(struct btf_verifier_env *env,
                                  const struct btf_type *struct_type,
                                  const struct btf_member *member,
                                  const struct btf_type *member_type);
        void (*log_details)(struct btf_verifier_env *env,
                            const struct btf_type *t);
        void (*show)(const struct btf *btf, const struct btf_type *t,
                         u32 type_id, void *data, u8 bits_offsets,
                         struct btf_show *show);
};

static const struct btf_kind_operations * const kind_ops[NR_BTF_KINDS];
static struct btf_type btf_void;

static int btf_resolve(struct btf_verifier_env *env,
                       const struct btf_type *t, u32 type_id);

static bool btf_type_is_modifier(const struct btf_type *t)
{
        /* Some of them is not strictly a C modifier
         * but they are grouped into the same bucket
         * for BTF concern:
         *   A type (t) that refers to another
         *   type through t->type AND its size cannot
         *   be determined without following the t->type.
         *
         * ptr does not fall into this bucket
         * because its size is always sizeof(void *).
         */
        switch (BTF_INFO_KIND(t->info)) {
        case BTF_KIND_TYPEDEF:
        case BTF_KIND_VOLATILE:
        case BTF_KIND_CONST:
        case BTF_KIND_RESTRICT:
                return true;
        }

        return false;
}

bool btf_type_is_void(const struct btf_type *t)
{
        return t == &btf_void;
}

static bool btf_type_is_fwd(const struct btf_type *t)
{
        return BTF_INFO_KIND(t->info) == BTF_KIND_FWD;
}

static bool btf_type_nosize(const struct btf_type *t)
{
        return btf_type_is_void(t) || btf_type_is_fwd(t) ||
               btf_type_is_func(t) || btf_type_is_func_proto(t);
}

static bool btf_type_nosize_or_null(const struct btf_type *t)
{
        return !t || btf_type_nosize(t);
}

static bool __btf_type_is_struct(const struct btf_type *t)
{
        return BTF_INFO_KIND(t->info) == BTF_KIND_STRUCT;
}

static bool btf_type_is_array(const struct btf_type *t)
{
        return BTF_INFO_KIND(t->info) == BTF_KIND_ARRAY;
}

static bool btf_type_is_datasec(const struct btf_type *t)
{
        return BTF_INFO_KIND(t->info) == BTF_KIND_DATASEC;
}

s32 btf_find_by_name_kind(const struct btf *btf, const char *name, u8 kind)
{
        const struct btf_type *t;
        const char *tname;
        u32 i;

        for (i = 1; i <= btf->nr_types; i++) {
                t = btf->types[i];
                if (BTF_INFO_KIND(t->info) != kind)
                        continue;

                tname = btf_name_by_offset(btf, t->name_off);
                if (!strcmp(tname, name))
                        return i;
        }

        return -ENOENT;
}

const struct btf_type *btf_type_skip_modifiers(const struct btf *btf,
                                               u32 id, u32 *res_id)
{
        const struct btf_type *t = btf_type_by_id(btf, id);

        while (btf_type_is_modifier(t)) {
                id = t->type;
                t = btf_type_by_id(btf, t->type);
        }

        if (res_id)
                *res_id = id;

        return t;
}

const struct btf_type *btf_type_resolve_ptr(const struct btf *btf,
                                            u32 id, u32 *res_id)
{
        const struct btf_type *t;

        t = btf_type_skip_modifiers(btf, id, NULL);
        if (!btf_type_is_ptr(t))
                return NULL;

        return btf_type_skip_modifiers(btf, t->type, res_id);
}

const struct btf_type *btf_type_resolve_func_ptr(const struct btf *btf,
                                                 u32 id, u32 *res_id)
{
        const struct btf_type *ptype;

        ptype = btf_type_resolve_ptr(btf, id, res_id);
        if (ptype && btf_type_is_func_proto(ptype))
                return ptype;

        return NULL;
}

/* Types that act only as a source, not sink or intermediate
 * type when resolving.
 */
static bool btf_type_is_resolve_source_only(const struct btf_type *t)
{
        return btf_type_is_var(t) ||
               btf_type_is_datasec(t);
}

/* What types need to be resolved?
 *
 * btf_type_is_modifier() is an obvious one.
 *
 * btf_type_is_struct() because its member refers to
 * another type (through member->type).
 *
 * btf_type_is_var() because the variable refers to
 * another type. btf_type_is_datasec() holds multiple
 * btf_type_is_var() types that need resolving.
 *
 * btf_type_is_array() because its element (array->type)
 * refers to another type.  Array can be thought of a
 * special case of struct while array just has the same
 * member-type repeated by array->nelems of times.
 */
static bool btf_type_needs_resolve(const struct btf_type *t)
{
        return btf_type_is_modifier(t) ||
               btf_type_is_ptr(t) ||
               btf_type_is_struct(t) ||
               btf_type_is_array(t) ||
               btf_type_is_var(t) ||
               btf_type_is_datasec(t);
}

/* t->size can be used */
static bool btf_type_has_size(const struct btf_type *t)
{
        switch (BTF_INFO_KIND(t->info)) {
        case BTF_KIND_INT:
        case BTF_KIND_STRUCT:
        case BTF_KIND_UNION:
        case BTF_KIND_ENUM:
        case BTF_KIND_DATASEC:
                return true;
        }

        return false;
}

static const char *btf_int_encoding_str(u8 encoding)
{
        if (encoding == 0)
                return "(none)";
        else if (encoding == BTF_INT_SIGNED)
                return "SIGNED";
        else if (encoding == BTF_INT_CHAR)
                return "CHAR";
        else if (encoding == BTF_INT_BOOL)
                return "BOOL";
        else
                return "UNKN";
}

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

static const struct btf_array *btf_type_array(const struct btf_type *t)
{
        return (const struct btf_array *)(t + 1);
}

static const struct btf_enum *btf_type_enum(const struct btf_type *t)
{
        return (const struct btf_enum *)(t + 1);
}

static const struct btf_var *btf_type_var(const struct btf_type *t)
{
        return (const struct btf_var *)(t + 1);
}

static const struct btf_kind_operations *btf_type_ops(const struct btf_type *t)
{
        return kind_ops[BTF_INFO_KIND(t->info)];
}

static bool btf_name_offset_valid(const struct btf *btf, u32 offset)
{
        return BTF_STR_OFFSET_VALID(offset) &&
                offset < btf->hdr.str_len;
}

static bool __btf_name_char_ok(char c, bool first, bool dot_ok)
{
        if ((first ? !isalpha(c) :
                     !isalnum(c)) &&
            c != '_' &&
            ((c == '.' && !dot_ok) ||
              c != '.'))
                return false;
        return true;
}

static bool __btf_name_valid(const struct btf *btf, u32 offset, bool dot_ok)
{
        /* offset must be valid */
        const char *src = &btf->strings[offset];
        const char *src_limit;

        if (!__btf_name_char_ok(*src, true, dot_ok))
                return false;

        /* set a limit on identifier length */
        src_limit = src + KSYM_NAME_LEN;
        src++;
        while (*src && src < src_limit) {
                if (!__btf_name_char_ok(*src, false, dot_ok))
                        return false;
                src++;
        }

        return !*src;
}

/* Only C-style identifier is permitted. This can be relaxed if
 * necessary.
 */
static bool btf_name_valid_identifier(const struct btf *btf, u32 offset)
{
        return __btf_name_valid(btf, offset, false);
}

static bool btf_name_valid_section(const struct btf *btf, u32 offset)
{
        return __btf_name_valid(btf, offset, true);
}

static const char *__btf_name_by_offset(const struct btf *btf, u32 offset)
{
        if (!offset)
                return "(anon)";
        else if (offset < btf->hdr.str_len)
                return &btf->strings[offset];
        else
                return "(invalid-name-offset)";
}

const char *btf_name_by_offset(const struct btf *btf, u32 offset)
{
        if (offset < btf->hdr.str_len)
                return &btf->strings[offset];

        return NULL;
}

const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id)
{
        if (type_id > btf->nr_types)
                return NULL;

        return btf->types[type_id];
}

/*
 * Regular int is not a bit field and it must be either
 * u8/u16/u32/u64 or __int128.
 */
static bool btf_type_int_is_regular(const struct btf_type *t)
{
        u8 nr_bits, nr_bytes;
        u32 int_data;

        int_data = btf_type_int(t);
        nr_bits = BTF_INT_BITS(int_data);
        nr_bytes = BITS_ROUNDUP_BYTES(nr_bits);
        if (BITS_PER_BYTE_MASKED(nr_bits) ||
            BTF_INT_OFFSET(int_data) ||
            (nr_bytes != sizeof(u8) && nr_bytes != sizeof(u16) &&
             nr_bytes != sizeof(u32) && nr_bytes != sizeof(u64) &&
             nr_bytes != (2 * sizeof(u64)))) {
                return false;
        }

        return true;
}

/*
 * Check that given struct member is a regular int with expected
 * offset and size.
 */
bool btf_member_is_reg_int(const struct btf *btf, const struct btf_type *s,
                           const struct btf_member *m,
                           u32 expected_offset, u32 expected_size)
{
        const struct btf_type *t;
        u32 id, int_data;
        u8 nr_bits;

        id = m->type;
        t = btf_type_id_size(btf, &id, NULL);
        if (!t || !btf_type_is_int(t))
                return false;

        int_data = btf_type_int(t);
        nr_bits = BTF_INT_BITS(int_data);
        if (btf_type_kflag(s)) {
                u32 bitfield_size = BTF_MEMBER_BITFIELD_SIZE(m->offset);
                u32 bit_offset = BTF_MEMBER_BIT_OFFSET(m->offset);

                /* if kflag set, int should be a regular int and
                 * bit offset should be at byte boundary.
                 */
                return !bitfield_size &&
                       BITS_ROUNDUP_BYTES(bit_offset) == expected_offset &&
                       BITS_ROUNDUP_BYTES(nr_bits) == expected_size;
        }

        if (BTF_INT_OFFSET(int_data) ||
            BITS_PER_BYTE_MASKED(m->offset) ||
            BITS_ROUNDUP_BYTES(m->offset) != expected_offset ||
            BITS_PER_BYTE_MASKED(nr_bits) ||
            BITS_ROUNDUP_BYTES(nr_bits) != expected_size)
                return false;

        return true;
}

/* Similar to btf_type_skip_modifiers() but does not skip typedefs. */
static const struct btf_type *btf_type_skip_qualifiers(const struct btf *btf,
                                                       u32 id)
{
        const struct btf_type *t = btf_type_by_id(btf, id);

        while (btf_type_is_modifier(t) &&
               BTF_INFO_KIND(t->info) != BTF_KIND_TYPEDEF) {
                id = t->type;
                t = btf_type_by_id(btf, t->type);
        }

        return t;
}

#define BTF_SHOW_MAX_ITER       10

#define BTF_KIND_BIT(kind)      (1ULL << kind)

/*
 * Populate show->state.name with type name information.
 * Format of type name is
 *
 * [.member_name = ] (type_name)
 */
static const char *btf_show_name(struct btf_show *show)
{
        /* BTF_MAX_ITER array suffixes "[]" */
        const char *array_suffixes = "[][][][][][][][][][]";
        const char *array_suffix = &array_suffixes[strlen(array_suffixes)];
        /* BTF_MAX_ITER pointer suffixes "*" */
        const char *ptr_suffixes = "**********";
        const char *ptr_suffix = &ptr_suffixes[strlen(ptr_suffixes)];
        const char *name = NULL, *prefix = "", *parens = "";
        const struct btf_member *m = show->state.member;
        const struct btf_type *t = show->state.type;
        const struct btf_array *array;
        u32 id = show->state.type_id;
        const char *member = NULL;
        bool show_member = false;
        u64 kinds = 0;
        int i;

        show->state.name[0] = '\0';

        /*
         * Don't show type name if we're showing an array member;
         * in that case we show the array type so don't need to repeat
         * ourselves for each member.
         */
        if (show->state.array_member)
                return "";

        /* Retrieve member name, if any. */
        if (m) {
                member = btf_name_by_offset(show->btf, m->name_off);
                show_member = strlen(member) > 0;
                id = m->type;
        }

        /*
         * Start with type_id, as we have resolved the struct btf_type *
         * via btf_modifier_show() past the parent typedef to the child
         * struct, int etc it is defined as.  In such cases, the type_id
         * still represents the starting type while the struct btf_type *
         * in our show->state points at the resolved type of the typedef.
         */
        t = btf_type_by_id(show->btf, id);
        if (!t)
                return "";

        /*
         * The goal here is to build up the right number of pointer and
         * array suffixes while ensuring the type name for a typedef
         * is represented.  Along the way we accumulate a list of
         * BTF kinds we have encountered, since these will inform later
         * display; for example, pointer types will not require an
         * opening "{" for struct, we will just display the pointer value.
         *
         * We also want to accumulate the right number of pointer or array
         * indices in the format string while iterating until we get to
         * the typedef/pointee/array member target type.
         *
         * We start by pointing at the end of pointer and array suffix
         * strings; as we accumulate pointers and arrays we move the pointer
         * or array string backwards so it will show the expected number of
         * '*' or '[]' for the type.  BTF_SHOW_MAX_ITER of nesting of pointers
         * and/or arrays and typedefs are supported as a precaution.
         *
         * We also want to get typedef name while proceeding to resolve
         * type it points to so that we can add parentheses if it is a
         * "typedef struct" etc.
         */
        for (i = 0; i < BTF_SHOW_MAX_ITER; i++) {

                switch (BTF_INFO_KIND(t->info)) {
                case BTF_KIND_TYPEDEF:
                        if (!name)
                                name = btf_name_by_offset(show->btf,
                                                               t->name_off);
                        kinds |= BTF_KIND_BIT(BTF_KIND_TYPEDEF);
                        id = t->type;
                        break;
                case BTF_KIND_ARRAY:
                        kinds |= BTF_KIND_BIT(BTF_KIND_ARRAY);
                        parens = "[";
                        if (!t)
                                return "";
                        array = btf_type_array(t);
                        if (array_suffix > array_suffixes)
                                array_suffix -= 2;
                        id = array->type;
                        break;
                case BTF_KIND_PTR:
                        kinds |= BTF_KIND_BIT(BTF_KIND_PTR);
                        if (ptr_suffix > ptr_suffixes)
                                ptr_suffix -= 1;
                        id = t->type;
                        break;
                default:
                        id = 0;
                        break;
                }
                if (!id)
                        break;
                t = btf_type_skip_qualifiers(show->btf, id);
        }
        /* We may not be able to represent this type; bail to be safe */
        if (i == BTF_SHOW_MAX_ITER)
                return "";

        if (!name)
                name = btf_name_by_offset(show->btf, t->name_off);

        switch (BTF_INFO_KIND(t->info)) {
        case BTF_KIND_STRUCT:
        case BTF_KIND_UNION:
                prefix = BTF_INFO_KIND(t->info) == BTF_KIND_STRUCT ?
                         "struct" : "union";
                /* if it's an array of struct/union, parens is already set */
                if (!(kinds & (BTF_KIND_BIT(BTF_KIND_ARRAY))))
                        parens = "{";
                break;
        case BTF_KIND_ENUM:
                prefix = "enum";
                break;
        default:
                break;
        }

        /* pointer does not require parens */
        if (kinds & BTF_KIND_BIT(BTF_KIND_PTR))
                parens = "";
        /* typedef does not require struct/union/enum prefix */
        if (kinds & BTF_KIND_BIT(BTF_KIND_TYPEDEF))
                prefix = "";

        if (!name)
                name = "";

        /* Even if we don't want type name info, we want parentheses etc */
        if (show->flags & BTF_SHOW_NONAME)
                snprintf(show->state.name, sizeof(show->state.name), "%s",
                         parens);
        else
                snprintf(show->state.name, sizeof(show->state.name),
                         "%s%s%s(%s%s%s%s%s%s)%s",
                         /* first 3 strings comprise ".member = " */
                         show_member ? "." : "",
                         show_member ? member : "",
                         show_member ? " = " : "",
                         /* ...next is our prefix (struct, enum, etc) */
                         prefix,
                         strlen(prefix) > 0 && strlen(name) > 0 ? " " : "",
                         /* ...this is the type name itself */
                         name,
                         /* ...suffixed by the appropriate '*', '[]' suffixes */
                         strlen(ptr_suffix) > 0 ? " " : "", ptr_suffix,
                         array_suffix, parens);

        return show->state.name;
}

static const char *__btf_show_indent(struct btf_show *show)
{
        const char *indents = "                                ";
        const char *indent = &indents[strlen(indents)];

        if ((indent - show->state.depth) >= indents)
                return indent - show->state.depth;
        return indents;
}

static const char *btf_show_indent(struct btf_show *show)
{
        return show->flags & BTF_SHOW_COMPACT ? "" : __btf_show_indent(show);
}

static const char *btf_show_newline(struct btf_show *show)
{
        return show->flags & BTF_SHOW_COMPACT ? "" : "\n";
}

static const char *btf_show_delim(struct btf_show *show)
{
        if (show->state.depth == 0)
                return "";

        if ((show->flags & BTF_SHOW_COMPACT) && show->state.type &&
                BTF_INFO_KIND(show->state.type->info) == BTF_KIND_UNION)
                return "|";

        return ",";
}

__printf(2, 3) static void btf_show(struct btf_show *show, const char *fmt, ...)
{
        va_list args;

        if (!show->state.depth_check) {
                va_start(args, fmt);
                show->showfn(show, fmt, args);
                va_end(args);
        }
}

/* Macros are used here as btf_show_type_value[s]() prepends and appends
 * format specifiers to the format specifier passed in; these do the work of
 * adding indentation, delimiters etc while the caller simply has to specify
 * the type value(s) in the format specifier + value(s).
 */
#define btf_show_type_value(show, fmt, value)                                  \
        do {                                                                   \
                if ((value) != 0 || (show->flags & BTF_SHOW_ZERO) ||           \
                    show->state.depth == 0) {                                  \
                        btf_show(show, "%s%s" fmt "%s%s",                      \
                                 btf_show_indent(show),                        \
                                 btf_show_name(show),                          \
                                 value, btf_show_delim(show),                  \
                                 btf_show_newline(show));                      \
                        if (show->state.depth > show->state.depth_to_show)     \
                                show->state.depth_to_show = show->state.depth; \
                }                                                              \
        } while (0)

#define btf_show_type_values(show, fmt, ...)                                   \
        do {                                                                   \
                btf_show(show, "%s%s" fmt "%s%s", btf_show_indent(show),       \
                         btf_show_name(show),                                  \
                         __VA_ARGS__, btf_show_delim(show),                    \
                         btf_show_newline(show));                              \
                if (show->state.depth > show->state.depth_to_show)             \
                        show->state.depth_to_show = show->state.depth;         \
        } while (0)

/* How much is left to copy to safe buffer after @data? */
static int btf_show_obj_size_left(struct btf_show *show, void *data)
{
        return show->obj.head + show->obj.size - data;

}

/* Is object pointed to by @data of @size already copied to our safe buffer? */
static bool btf_show_obj_is_safe(struct btf_show *show, void *data, int size)
{
        return data >= show->obj.data &&
               (data + size) < (show->obj.data + BTF_SHOW_OBJ_SAFE_SIZE);
}

/*
 * If object pointed to by @data of @size falls within our safe buffer, return
 * the equivalent pointer to the same safe data.  Assumes
 * copy_from_kernel_nofault() has already happened and our safe buffer is
 * populated.
 */
static void *__btf_show_obj_safe(struct btf_show *show, void *data, int size)
{
        if (btf_show_obj_is_safe(show, data, size))
                return show->obj.safe + (data - show->obj.data);
        return NULL;
}

/*
 * Return a safe-to-access version of data pointed to by @data.
 * We do this by copying the relevant amount of information
 * to the struct btf_show obj.safe buffer using copy_from_kernel_nofault().
 *
 * If BTF_SHOW_UNSAFE is specified, just return data as-is; no
 * safe copy is needed.
 *
 * Otherwise we need to determine if we have the required amount
 * of data (determined by the @data pointer and the size of the
 * largest base type we can encounter (represented by
 * BTF_SHOW_OBJ_BASE_TYPE_SIZE). Having that much data ensures
 * that we will be able to print some of the current object,
 * and if more is needed a copy will be triggered.
 * Some objects such as structs will not fit into the buffer;
 * in such cases additional copies when we iterate over their
 * members may be needed.
 *
 * btf_show_obj_safe() is used to return a safe buffer for
 * btf_show_start_type(); this ensures that as we recurse into
 * nested types we always have safe data for the given type.
 * This approach is somewhat wasteful; it's possible for example
 * that when iterating over a large union we'll end up copying the
 * same data repeatedly, but the goal is safety not performance.
 * We use stack data as opposed to per-CPU buffers because the
 * iteration over a type can take some time, and preemption handling
 * would greatly complicate use of the safe buffer.
 */
static void *btf_show_obj_safe(struct btf_show *show,
                               const struct btf_type *t,
                               void *data)
{
        const struct btf_type *rt;
        int size_left, size;
        void *safe = NULL;

        if (show->flags & BTF_SHOW_UNSAFE)
                return data;

        rt = btf_resolve_size(show->btf, t, &size);
        if (IS_ERR(rt)) {
                show->state.status = PTR_ERR(rt);
                return NULL;
        }

        /*
         * Is this toplevel object? If so, set total object size and
         * initialize pointers.  Otherwise check if we still fall within
         * our safe object data.
         */
        if (show->state.depth == 0) {
                show->obj.size = size;
                show->obj.head = data;
        } else {
                /*
                 * If the size of the current object is > our remaining
                 * safe buffer we _may_ need to do a new copy.  However
                 * consider the case of a nested struct; it's size pushes
                 * us over the safe buffer limit, but showing any individual
                 * struct members does not.  In such cases, we don't need
                 * to initiate a fresh copy yet; however we definitely need
                 * at least BTF_SHOW_OBJ_BASE_TYPE_SIZE bytes left
                 * in our buffer, regardless of the current object size.
                 * The logic here is that as we resolve types we will
                 * hit a base type at some point, and we need to be sure
                 * the next chunk of data is safely available to display
                 * that type info safely.  We cannot rely on the size of
                 * the current object here because it may be much larger
                 * than our current buffer (e.g. task_struct is 8k).
                 * All we want to do here is ensure that we can print the
                 * next basic type, which we can if either
                 * - the current type size is within the safe buffer; or
                 * - at least BTF_SHOW_OBJ_BASE_TYPE_SIZE bytes are left in
                 *   the safe buffer.
                 */
                safe = __btf_show_obj_safe(show, data,
                                           min(size,
                                               BTF_SHOW_OBJ_BASE_TYPE_SIZE));
        }

        /*
         * We need a new copy to our safe object, either because we haven't
         * yet copied and are intializing safe data, or because the data
         * we want falls outside the boundaries of the safe object.
         */
        if (!safe) {
                size_left = btf_show_obj_size_left(show, data);
                if (size_left > BTF_SHOW_OBJ_SAFE_SIZE)
                        size_left = BTF_SHOW_OBJ_SAFE_SIZE;
                show->state.status = copy_from_kernel_nofault(show->obj.safe,
                                                              data, size_left);
                if (!show->state.status) {
                        show->obj.data = data;
                        safe = show->obj.safe;
                }
        }

        return safe;
}

/*
 * Set the type we are starting to show and return a safe data pointer
 * to be used for showing the associated data.
 */
static void *btf_show_start_type(struct btf_show *show,
                                 const struct btf_type *t,
                                 u32 type_id, void *data)
{
        show->state.type = t;
        show->state.type_id = type_id;
        show->state.name[0] = '\0';

        return btf_show_obj_safe(show, t, data);
}

static void btf_show_end_type(struct btf_show *show)
{
        show->state.type = NULL;
        show->state.type_id = 0;
        show->state.name[0] = '\0';
}

static void *btf_show_start_aggr_type(struct btf_show *show,
                                      const struct btf_type *t,
                                      u32 type_id, void *data)
{
        void *safe_data = btf_show_start_type(show, t, type_id, data);

        if (!safe_data)
                return safe_data;

        btf_show(show, "%s%s%s", btf_show_indent(show),
                 btf_show_name(show),
                 btf_show_newline(show));
        show->state.depth++;
        return safe_data;
}

static void btf_show_end_aggr_type(struct btf_show *show,
                                   const char *suffix)
{
        show->state.depth--;
        btf_show(show, "%s%s%s%s", btf_show_indent(show), suffix,
                 btf_show_delim(show), btf_show_newline(show));
        btf_show_end_type(show);
}

static void btf_show_start_member(struct btf_show *show,
                                  const struct btf_member *m)
{
        show->state.member = m;
}

static void btf_show_start_array_member(struct btf_show *show)
{
        show->state.array_member = 1;
        btf_show_start_member(show, NULL);
}

static void btf_show_end_member(struct btf_show *show)
{
        show->state.member = NULL;
}

static void btf_show_end_array_member(struct btf_show *show)
{
        show->state.array_member = 0;
        btf_show_end_member(show);
}

static void *btf_show_start_array_type(struct btf_show *show,
                                       const struct btf_type *t,
                                       u32 type_id,
                                       u16 array_encoding,
                                       void *data)
{
        show->state.array_encoding = array_encoding;
        show->state.array_terminated = 0;
        return btf_show_start_aggr_type(show, t, type_id, data);
}

static void btf_show_end_array_type(struct btf_show *show)
{
        show->state.array_encoding = 0;
        show->state.array_terminated = 0;
        btf_show_end_aggr_type(show, "]");
}

static void *btf_show_start_struct_type(struct btf_show *show,
                                        const struct btf_type *t,
                                        u32 type_id,
                                        void *data)
{
        return btf_show_start_aggr_type(show, t, type_id, data);
}

static void btf_show_end_struct_type(struct btf_show *show)
{
        btf_show_end_aggr_type(show, "}");
}

__printf(2, 3) static void __btf_verifier_log(struct bpf_verifier_log *log,
                                              const char *fmt, ...)
{
        va_list args;

        va_start(args, fmt);
        bpf_verifier_vlog(log, fmt, args);
        va_end(args);
}

__printf(2, 3) static void btf_verifier_log(struct btf_verifier_env *env,
                                            const char *fmt, ...)
{
        struct bpf_verifier_log *log = &env->log;
        va_list args;

        if (!bpf_verifier_log_needed(log))
                return;

        va_start(args, fmt);
        bpf_verifier_vlog(log, fmt, args);
        va_end(args);
}

__printf(4, 5) static void __btf_verifier_log_type(struct btf_verifier_env *env,
                                                   const struct btf_type *t,
                                                   bool log_details,
                                                   const char *fmt, ...)
{
        struct bpf_verifier_log *log = &env->log;
        u8 kind = BTF_INFO_KIND(t->info);
        struct btf *btf = env->btf;
        va_list args;

        if (!bpf_verifier_log_needed(log))
                return;

        /* btf verifier prints all types it is processing via
         * btf_verifier_log_type(..., fmt = NULL).
         * Skip those prints for in-kernel BTF verification.
         */
        if (log->level == BPF_LOG_KERNEL && !fmt)
                return;

        __btf_verifier_log(log, "[%u] %s %s%s",
                           env->log_type_id,
                           btf_kind_str[kind],
                           __btf_name_by_offset(btf, t->name_off),
                           log_details ? " " : "");

        if (log_details)
                btf_type_ops(t)->log_details(env, t);

        if (fmt && *fmt) {
                __btf_verifier_log(log, " ");
                va_start(args, fmt);
                bpf_verifier_vlog(log, fmt, args);
                va_end(args);
        }

        __btf_verifier_log(log, "\n");
}

#define btf_verifier_log_type(env, t, ...) \
        __btf_verifier_log_type((env), (t), true, __VA_ARGS__)
#define btf_verifier_log_basic(env, t, ...) \
        __btf_verifier_log_type((env), (t), false, __VA_ARGS__)

__printf(4, 5)
static void btf_verifier_log_member(struct btf_verifier_env *env,
                                    const struct btf_type *struct_type,
                                    const struct btf_member *member,
                                    const char *fmt, ...)
{
        struct bpf_verifier_log *log = &env->log;
        struct btf *btf = env->btf;
        va_list args;

        if (!bpf_verifier_log_needed(log))
                return;

        if (log->level == BPF_LOG_KERNEL && !fmt)
                return;
        /* The CHECK_META phase already did a btf dump.
         *
         * If member is logged again, it must hit an error in
         * parsing this member.  It is useful to print out which
         * struct this member belongs to.
         */
        if (env->phase != CHECK_META)
                btf_verifier_log_type(env, struct_type, NULL);

        if (btf_type_kflag(struct_type))
                __btf_verifier_log(log,
                                   "\t%s type_id=%u bitfield_size=%u bits_offset=%u",
                                   __btf_name_by_offset(btf, member->name_off),
                                   member->type,
                                   BTF_MEMBER_BITFIELD_SIZE(member->offset),
                                   BTF_MEMBER_BIT_OFFSET(member->offset));
        else
                __btf_verifier_log(log, "\t%s type_id=%u bits_offset=%u",
                                   __btf_name_by_offset(btf, member->name_off),
                                   member->type, member->offset);

        if (fmt && *fmt) {
                __btf_verifier_log(log, " ");
                va_start(args, fmt);
                bpf_verifier_vlog(log, fmt, args);
                va_end(args);
        }

        __btf_verifier_log(log, "\n");
}

__printf(4, 5)
static void btf_verifier_log_vsi(struct btf_verifier_env *env,
                                 const struct btf_type *datasec_type,
                                 const struct btf_var_secinfo *vsi,
                                 const char *fmt, ...)
{
        struct bpf_verifier_log *log = &env->log;
        va_list args;

        if (!bpf_verifier_log_needed(log))
                return;
        if (log->level == BPF_LOG_KERNEL && !fmt)
                return;
        if (env->phase != CHECK_META)
                btf_verifier_log_type(env, datasec_type, NULL);

        __btf_verifier_log(log, "\t type_id=%u offset=%u size=%u",
                           vsi->type, vsi->offset, vsi->size);
        if (fmt && *fmt) {
                __btf_verifier_log(log, " ");
                va_start(args, fmt);
                bpf_verifier_vlog(log, fmt, args);
                va_end(args);
        }

        __btf_verifier_log(log, "\n");
}

static void btf_verifier_log_hdr(struct btf_verifier_env *env,
                                 u32 btf_data_size)
{
        struct bpf_verifier_log *log = &env->log;
        const struct btf *btf = env->btf;
        const struct btf_header *hdr;

        if (!bpf_verifier_log_needed(log))
                return;

        if (log->level == BPF_LOG_KERNEL)
                return;
        hdr = &btf->hdr;
        __btf_verifier_log(log, "magic: 0x%x\n", hdr->magic);
        __btf_verifier_log(log, "version: %u\n", hdr->version);
        __btf_verifier_log(log, "flags: 0x%x\n", hdr->flags);
        __btf_verifier_log(log, "hdr_len: %u\n", hdr->hdr_len);
        __btf_verifier_log(log, "type_off: %u\n", hdr->type_off);
        __btf_verifier_log(log, "type_len: %u\n", hdr->type_len);
        __btf_verifier_log(log, "str_off: %u\n", hdr->str_off);
        __btf_verifier_log(log, "str_len: %u\n", hdr->str_len);
        __btf_verifier_log(log, "btf_total_size: %u\n", btf_data_size);
}

static int btf_add_type(struct btf_verifier_env *env, struct btf_type *t)
{
        struct btf *btf = env->btf;

        /* < 2 because +1 for btf_void which is always in btf->types[0].
         * btf_void is not accounted in btf->nr_types because btf_void
         * does not come from the BTF file.
         */
        if (btf->types_size - btf->nr_types < 2) {
                /* Expand 'types' array */

                struct btf_type **new_types;
                u32 expand_by, new_size;

                if (btf->types_size == BTF_MAX_TYPE) {
                        btf_verifier_log(env, "Exceeded max num of types");
                        return -E2BIG;
                }

                expand_by = max_t(u32, btf->types_size >> 2, 16);
                new_size = min_t(u32, BTF_MAX_TYPE,
                                 btf->types_size + expand_by);

                new_types = kvcalloc(new_size, sizeof(*new_types),
                                     GFP_KERNEL | __GFP_NOWARN);
                if (!new_types)
                        return -ENOMEM;

                if (btf->nr_types == 0)
                        new_types[0] = &btf_void;
                else
                        memcpy(new_types, btf->types,
                               sizeof(*btf->types) * (btf->nr_types + 1));

                kvfree(btf->types);
                btf->types = new_types;
                btf->types_size = new_size;
        }

        btf->types[++(btf->nr_types)] = t;

        return 0;
}

static int btf_alloc_id(struct btf *btf)
{
        int id;

        idr_preload(GFP_KERNEL);
        spin_lock_bh(&btf_idr_lock);
        id = idr_alloc_cyclic(&btf_idr, btf, 1, INT_MAX, GFP_ATOMIC);
        if (id > 0)
                btf->id = id;
        spin_unlock_bh(&btf_idr_lock);
        idr_preload_end();

        if (WARN_ON_ONCE(!id))
                return -ENOSPC;

        return id > 0 ? 0 : id;
}

static void btf_free_id(struct btf *btf)
{
        unsigned long flags;

        /*
         * In map-in-map, calling map_delete_elem() on outer
         * map will call bpf_map_put on the inner map.
         * It will then eventually call btf_free_id()
         * on the inner map.  Some of the map_delete_elem()
         * implementation may have irq disabled, so
         * we need to use the _irqsave() version instead
         * of the _bh() version.
         */
        spin_lock_irqsave(&btf_idr_lock, flags);
        idr_remove(&btf_idr, btf->id);
        spin_unlock_irqrestore(&btf_idr_lock, flags);
}

static void btf_free(struct btf *btf)
{
        kvfree(btf->types);
        kvfree(btf->resolved_sizes);
        kvfree(btf->resolved_ids);
        kvfree(btf->data);
        kfree(btf);
}

static void btf_free_rcu(struct rcu_head *rcu)
{
        struct btf *btf = container_of(rcu, struct btf, rcu);

        btf_free(btf);
}

void btf_put(struct btf *btf)
{
        if (btf && refcount_dec_and_test(&btf->refcnt)) {
                btf_free_id(btf);
                call_rcu(&btf->rcu, btf_free_rcu);
        }
}

static int env_resolve_init(struct btf_verifier_env *env)
{
        struct btf *btf = env->btf;
        u32 nr_types = btf->nr_types;
        u32 *resolved_sizes = NULL;
        u32 *resolved_ids = NULL;
        u8 *visit_states = NULL;

        /* +1 for btf_void */
        resolved_sizes = kvcalloc(nr_types + 1, sizeof(*resolved_sizes),
                                  GFP_KERNEL | __GFP_NOWARN);
        if (!resolved_sizes)
                goto nomem;

        resolved_ids = kvcalloc(nr_types + 1, sizeof(*resolved_ids),
                                GFP_KERNEL | __GFP_NOWARN);
        if (!resolved_ids)
                goto nomem;

        visit_states = kvcalloc(nr_types + 1, sizeof(*visit_states),
                                GFP_KERNEL | __GFP_NOWARN);
        if (!visit_states)
                goto nomem;

        btf->resolved_sizes = resolved_sizes;
        btf->resolved_ids = resolved_ids;
        env->visit_states = visit_states;

        return 0;

nomem:
        kvfree(resolved_sizes);
        kvfree(resolved_ids);
        kvfree(visit_states);
        return -ENOMEM;
}

static void btf_verifier_env_free(struct btf_verifier_env *env)
{
        kvfree(env->visit_states);
        kfree(env);
}

static bool env_type_is_resolve_sink(const struct btf_verifier_env *env,
                                     const struct btf_type *next_type)
{
        switch (env->resolve_mode) {
        case RESOLVE_TBD:
                /* int, enum or void is a sink */
                return !btf_type_needs_resolve(next_type);
        case RESOLVE_PTR:
                /* int, enum, void, struct, array, func or func_proto is a sink
                 * for ptr
                 */
                return !btf_type_is_modifier(next_type) &&
                        !btf_type_is_ptr(next_type);
        case RESOLVE_STRUCT_OR_ARRAY:
                /* int, enum, void, ptr, func or func_proto is a sink
                 * for struct and array
                 */
                return !btf_type_is_modifier(next_type) &&
                        !btf_type_is_array(next_type) &&
                        !btf_type_is_struct(next_type);
        default:
                BUG();
        }
}

static bool env_type_is_resolved(const struct btf_verifier_env *env,
                                 u32 type_id)
{
        return env->visit_states[type_id] == RESOLVED;
}

static int env_stack_push(struct btf_verifier_env *env,
                          const struct btf_type *t, u32 type_id)
{
        struct resolve_vertex *v;

        if (env->top_stack == MAX_RESOLVE_DEPTH)
                return -E2BIG;

        if (env->visit_states[type_id] != NOT_VISITED)
                return -EEXIST;

        env->visit_states[type_id] = VISITED;

        v = &env->stack[env->top_stack++];
        v->t = t;
        v->type_id = type_id;
        v->next_member = 0;

        if (env->resolve_mode == RESOLVE_TBD) {
                if (btf_type_is_ptr(t))
                        env->resolve_mode = RESOLVE_PTR;
                else if (btf_type_is_struct(t) || btf_type_is_array(t))
                        env->resolve_mode = RESOLVE_STRUCT_OR_ARRAY;
        }

        return 0;
}

static void env_stack_set_next_member(struct btf_verifier_env *env,
                                      u16 next_member)
{
        env->stack[env->top_stack - 1].next_member = next_member;
}

static void env_stack_pop_resolved(struct btf_verifier_env *env,
                                   u32 resolved_type_id,
                                   u32 resolved_size)
{
        u32 type_id = env->stack[--(env->top_stack)].type_id;
        struct btf *btf = env->btf;

        btf->resolved_sizes[type_id] = resolved_size;
        btf->resolved_ids[type_id] = resolved_type_id;
        env->visit_states[type_id] = RESOLVED;
}

static const struct resolve_vertex *env_stack_peak(struct btf_verifier_env *env)
{
        return env->top_stack ? &env->stack[env->top_stack - 1] : NULL;
}

/* Resolve the size of a passed-in "type"
 *
 * type: is an array (e.g. u32 array[x][y])
 * return type: type "u32[x][y]", i.e. BTF_KIND_ARRAY,
 * *type_size: (x * y * sizeof(u32)).  Hence, *type_size always
 *             corresponds to the return type.
 * *elem_type: u32
 * *elem_id: id of u32
 * *total_nelems: (x * y).  Hence, individual elem size is
 *                (*type_size / *total_nelems)
 * *type_id: id of type if it's changed within the function, 0 if not
 *
 * type: is not an array (e.g. const struct X)
 * return type: type "struct X"
 * *type_size: sizeof(struct X)
 * *elem_type: same as return type ("struct X")
 * *elem_id: 0
 * *total_nelems: 1
 * *type_id: id of type if it's changed within the function, 0 if not
 */
static const struct btf_type *
__btf_resolve_size(const struct btf *btf, const struct btf_type *type,
                   u32 *type_size, const struct btf_type **elem_type,
                   u32 *elem_id, u32 *total_nelems, u32 *type_id)
{
        const struct btf_type *array_type = NULL;
        const struct btf_array *array = NULL;
        u32 i, size, nelems = 1, id = 0;

        for (i = 0; i < MAX_RESOLVE_DEPTH; i++) {
                switch (BTF_INFO_KIND(type->info)) {
                /* type->size can be used */
                case BTF_KIND_INT:
                case BTF_KIND_STRUCT:
                case BTF_KIND_UNION:
                case BTF_KIND_ENUM:
                        size = type->size;
                        goto resolved;

                case BTF_KIND_PTR:
                        size = sizeof(void *);
                        goto resolved;

                /* Modifiers */
                case BTF_KIND_TYPEDEF:
                case BTF_KIND_VOLATILE:
                case BTF_KIND_CONST:
                case BTF_KIND_RESTRICT:
                        id = type->type;
                        type = btf_type_by_id(btf, type->type);
                        break;

                case BTF_KIND_ARRAY:
                        if (!array_type)
                                array_type = type;
                        array = btf_type_array(type);
                        if (nelems && array->nelems > U32_MAX / nelems)
                                return ERR_PTR(-EINVAL);
                        nelems *= array->nelems;
                        type = btf_type_by_id(btf, array->type);
                        break;

                /* type without size */
                default:
                        return ERR_PTR(-EINVAL);
                }
        }

        return ERR_PTR(-EINVAL);

resolved:
        if (nelems && size > U32_MAX / nelems)
                return ERR_PTR(-EINVAL);

        *type_size = nelems * size;
        if (total_nelems)
                *total_nelems = nelems;
        if (elem_type)
                *elem_type = type;
        if (elem_id)
                *elem_id = array ? array->type : 0;
        if (type_id && id)
                *type_id = id;

        return array_type ? : type;
}

const struct btf_type *
btf_resolve_size(const struct btf *btf, const struct btf_type *type,
                 u32 *type_size)
{
        return __btf_resolve_size(btf, type, type_size, NULL, NULL, NULL, NULL);
}

/* The input param "type_id" must point to a needs_resolve type */
static const struct btf_type *btf_type_id_resolve(const struct btf *btf,
                                                  u32 *type_id)
{
        *type_id = btf->resolved_ids[*type_id];
        return btf_type_by_id(btf, *type_id);
}

const struct btf_type *btf_type_id_size(const struct btf *btf,
                                        u32 *type_id, u32 *ret_size)
{
        const struct btf_type *size_type;
        u32 size_type_id = *type_id;
        u32 size = 0;

        size_type = btf_type_by_id(btf, size_type_id);
        if (btf_type_nosize_or_null(size_type))
                return NULL;

        if (btf_type_has_size(size_type)) {
                size = size_type->size;
        } else if (btf_type_is_array(size_type)) {
                size = btf->resolved_sizes[size_type_id];
        } else if (btf_type_is_ptr(size_type)) {
                size = sizeof(void *);
        } else {
                if (WARN_ON_ONCE(!btf_type_is_modifier(size_type) &&
                                 !btf_type_is_var(size_type)))
                        return NULL;

                size_type_id = btf->resolved_ids[size_type_id];
                size_type = btf_type_by_id(btf, size_type_id);
                if (btf_type_nosize_or_null(size_type))
                        return NULL;
                else if (btf_type_has_size(size_type))
                        size = size_type->size;
                else if (btf_type_is_array(size_type))
                        size = btf->resolved_sizes[size_type_id];
                else if (btf_type_is_ptr(size_type))
                        size = sizeof(void *);
                else
                        return NULL;
        }

        *type_id = size_type_id;
        if (ret_size)
                *ret_size = size;

        return size_type;
}

static int btf_df_check_member(struct btf_verifier_env *env,
                               const struct btf_type *struct_type,
                               const struct btf_member *member,
                               const struct btf_type *member_type)
{
        btf_verifier_log_basic(env, struct_type,
                               "Unsupported check_member");
        return -EINVAL;
}

static int btf_df_check_kflag_member(struct btf_verifier_env *env,
                                     const struct btf_type *struct_type,
                                     const struct btf_member *member,
                                     const struct btf_type *member_type)
{
        btf_verifier_log_basic(env, struct_type,
                               "Unsupported check_kflag_member");
        return -EINVAL;
}

/* Used for ptr, array and struct/union type members.
 * int, enum and modifier types have their specific callback functions.
 */
static int btf_generic_check_kflag_member(struct btf_verifier_env *env,
                                          const struct btf_type *struct_type,
                                          const struct btf_member *member,
                                          const struct btf_type *member_type)
{
        if (BTF_MEMBER_BITFIELD_SIZE(member->offset)) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Invalid member bitfield_size");
                return -EINVAL;
        }

        /* bitfield size is 0, so member->offset represents bit offset only.
         * It is safe to call non kflag check_member variants.
         */
        return btf_type_ops(member_type)->check_member(env, struct_type,
                                                       member,
                                                       member_type);
}

static int btf_df_resolve(struct btf_verifier_env *env,
                          const struct resolve_vertex *v)
{
        btf_verifier_log_basic(env, v->t, "Unsupported resolve");
        return -EINVAL;
}

static void btf_df_show(const struct btf *btf, const struct btf_type *t,
                        u32 type_id, void *data, u8 bits_offsets,
                        struct btf_show *show)
{
        btf_show(show, "<unsupported kind:%u>", BTF_INFO_KIND(t->info));
}

static int btf_int_check_member(struct btf_verifier_env *env,
                                const struct btf_type *struct_type,
                                const struct btf_member *member,
                                const struct btf_type *member_type)
{
        u32 int_data = btf_type_int(member_type);
        u32 struct_bits_off = member->offset;
        u32 struct_size = struct_type->size;
        u32 nr_copy_bits;
        u32 bytes_offset;

        if (U32_MAX - struct_bits_off < BTF_INT_OFFSET(int_data)) {
                btf_verifier_log_member(env, struct_type, member,
                                        "bits_offset exceeds U32_MAX");
                return -EINVAL;
        }

        struct_bits_off += BTF_INT_OFFSET(int_data);
        bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
        nr_copy_bits = BTF_INT_BITS(int_data) +
                BITS_PER_BYTE_MASKED(struct_bits_off);

        if (nr_copy_bits > BITS_PER_U128) {
                btf_verifier_log_member(env, struct_type, member,
                                        "nr_copy_bits exceeds 128");
                return -EINVAL;
        }

        if (struct_size < bytes_offset ||
            struct_size - bytes_offset < BITS_ROUNDUP_BYTES(nr_copy_bits)) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Member exceeds struct_size");
                return -EINVAL;
        }

        return 0;
}

static int btf_int_check_kflag_member(struct btf_verifier_env *env,
                                      const struct btf_type *struct_type,
                                      const struct btf_member *member,
                                      const struct btf_type *member_type)
{
        u32 struct_bits_off, nr_bits, nr_int_data_bits, bytes_offset;
        u32 int_data = btf_type_int(member_type);
        u32 struct_size = struct_type->size;
        u32 nr_copy_bits;

        /* a regular int type is required for the kflag int member */
        if (!btf_type_int_is_regular(member_type)) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Invalid member base type");
                return -EINVAL;
        }

        /* check sanity of bitfield size */
        nr_bits = BTF_MEMBER_BITFIELD_SIZE(member->offset);
        struct_bits_off = BTF_MEMBER_BIT_OFFSET(member->offset);
        nr_int_data_bits = BTF_INT_BITS(int_data);
        if (!nr_bits) {
                /* Not a bitfield member, member offset must be at byte
                 * boundary.
                 */
                if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
                        btf_verifier_log_member(env, struct_type, member,
                                                "Invalid member offset");
                        return -EINVAL;
                }

                nr_bits = nr_int_data_bits;
        } else if (nr_bits > nr_int_data_bits) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Invalid member bitfield_size");
                return -EINVAL;
        }

        bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
        nr_copy_bits = nr_bits + BITS_PER_BYTE_MASKED(struct_bits_off);
        if (nr_copy_bits > BITS_PER_U128) {
                btf_verifier_log_member(env, struct_type, member,
                                        "nr_copy_bits exceeds 128");
                return -EINVAL;
        }

        if (struct_size < bytes_offset ||
            struct_size - bytes_offset < BITS_ROUNDUP_BYTES(nr_copy_bits)) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Member exceeds struct_size");
                return -EINVAL;
        }

        return 0;
}

static s32 btf_int_check_meta(struct btf_verifier_env *env,
                              const struct btf_type *t,
                              u32 meta_left)
{
        u32 int_data, nr_bits, meta_needed = sizeof(int_data);
        u16 encoding;

        if (meta_left < meta_needed) {
                btf_verifier_log_basic(env, t,
                                       "meta_left:%u meta_needed:%u",
                                       meta_left, meta_needed);
                return -EINVAL;
        }

        if (btf_type_vlen(t)) {
                btf_verifier_log_type(env, t, "vlen != 0");
                return -EINVAL;
        }

        if (btf_type_kflag(t)) {
                btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
                return -EINVAL;
        }

        int_data = btf_type_int(t);
        if (int_data & ~BTF_INT_MASK) {
                btf_verifier_log_basic(env, t, "Invalid int_data:%x",
                                       int_data);
                return -EINVAL;
        }

        nr_bits = BTF_INT_BITS(int_data) + BTF_INT_OFFSET(int_data);

        if (nr_bits > BITS_PER_U128) {
                btf_verifier_log_type(env, t, "nr_bits exceeds %zu",
                                      BITS_PER_U128);
                return -EINVAL;
        }

        if (BITS_ROUNDUP_BYTES(nr_bits) > t->size) {
                btf_verifier_log_type(env, t, "nr_bits exceeds type_size");
                return -EINVAL;
        }

        /*
         * Only one of the encoding bits is allowed and it
         * should be sufficient for the pretty print purpose (i.e. decoding).
         * Multiple bits can be allowed later if it is found
         * to be insufficient.
         */
        encoding = BTF_INT_ENCODING(int_data);
        if (encoding &&
            encoding != BTF_INT_SIGNED &&
            encoding != BTF_INT_CHAR &&
            encoding != BTF_INT_BOOL) {
                btf_verifier_log_type(env, t, "Unsupported encoding");
                return -ENOTSUPP;
        }

        btf_verifier_log_type(env, t, NULL);

        return meta_needed;
}

static void btf_int_log(struct btf_verifier_env *env,
                        const struct btf_type *t)
{
        int int_data = btf_type_int(t);

        btf_verifier_log(env,
                         "size=%u bits_offset=%u nr_bits=%u encoding=%s",
                         t->size, BTF_INT_OFFSET(int_data),
                         BTF_INT_BITS(int_data),
                         btf_int_encoding_str(BTF_INT_ENCODING(int_data)));
}

static void btf_int128_print(struct btf_show *show, void *data)
{
        /* data points to a __int128 number.
         * Suppose
         *     int128_num = *(__int128 *)data;
         * The below formulas shows what upper_num and lower_num represents:
         *     upper_num = int128_num >> 64;
         *     lower_num = int128_num & 0xffffffffFFFFFFFFULL;
         */
        u64 upper_num, lower_num;

#ifdef __BIG_ENDIAN_BITFIELD
        upper_num = *(u64 *)data;
        lower_num = *(u64 *)(data + 8);
#else
        upper_num = *(u64 *)(data + 8);
        lower_num = *(u64 *)data;
#endif
        if (upper_num == 0)
                btf_show_type_value(show, "0x%llx", lower_num);
        else
                btf_show_type_values(show, "0x%llx%016llx", upper_num,
                                     lower_num);
}

static void btf_int128_shift(u64 *print_num, u16 left_shift_bits,
                             u16 right_shift_bits)
{
        u64 upper_num, lower_num;

#ifdef __BIG_ENDIAN_BITFIELD
        upper_num = print_num[0];
        lower_num = print_num[1];
#else
        upper_num = print_num[1];
        lower_num = print_num[0];
#endif

        /* shake out un-needed bits by shift/or operations */
        if (left_shift_bits >= 64) {
                upper_num = lower_num << (left_shift_bits - 64);
                lower_num = 0;
        } else {
                upper_num = (upper_num << left_shift_bits) |
                            (lower_num >> (64 - left_shift_bits));
                lower_num = lower_num << left_shift_bits;
        }

        if (right_shift_bits >= 64) {
                lower_num = upper_num >> (right_shift_bits - 64);
                upper_num = 0;
        } else {
                lower_num = (lower_num >> right_shift_bits) |
                            (upper_num << (64 - right_shift_bits));
                upper_num = upper_num >> right_shift_bits;
        }

#ifdef __BIG_ENDIAN_BITFIELD
        print_num[0] = upper_num;
        print_num[1] = lower_num;
#else
        print_num[0] = lower_num;
        print_num[1] = upper_num;
#endif
}

static void btf_bitfield_show(void *data, u8 bits_offset,
                              u8 nr_bits, struct btf_show *show)
{
        u16 left_shift_bits, right_shift_bits;
        u8 nr_copy_bytes;
        u8 nr_copy_bits;
        u64 print_num[2] = {};

        nr_copy_bits = nr_bits + bits_offset;
        nr_copy_bytes = BITS_ROUNDUP_BYTES(nr_copy_bits);

        memcpy(print_num, data, nr_copy_bytes);

#ifdef __BIG_ENDIAN_BITFIELD
        left_shift_bits = bits_offset;
#else
        left_shift_bits = BITS_PER_U128 - nr_copy_bits;
#endif
        right_shift_bits = BITS_PER_U128 - nr_bits;

        btf_int128_shift(print_num, left_shift_bits, right_shift_bits);
        btf_int128_print(show, print_num);
}


static void btf_int_bits_show(const struct btf *btf,
                              const struct btf_type *t,
                              void *data, u8 bits_offset,
                              struct btf_show *show)
{
        u32 int_data = btf_type_int(t);
        u8 nr_bits = BTF_INT_BITS(int_data);
        u8 total_bits_offset;

        /*
         * bits_offset is at most 7.
         * BTF_INT_OFFSET() cannot exceed 128 bits.
         */
        total_bits_offset = bits_offset + BTF_INT_OFFSET(int_data);
        data += BITS_ROUNDDOWN_BYTES(total_bits_offset);
        bits_offset = BITS_PER_BYTE_MASKED(total_bits_offset);
        btf_bitfield_show(data, bits_offset, nr_bits, show);
}

static void btf_int_show(const struct btf *btf, const struct btf_type *t,
                         u32 type_id, void *data, u8 bits_offset,
                         struct btf_show *show)
{
        u32 int_data = btf_type_int(t);
        u8 encoding = BTF_INT_ENCODING(int_data);
        bool sign = encoding & BTF_INT_SIGNED;
        u8 nr_bits = BTF_INT_BITS(int_data);
        void *safe_data;

        safe_data = btf_show_start_type(show, t, type_id, data);
        if (!safe_data)
                return;

        if (bits_offset || BTF_INT_OFFSET(int_data) ||
            BITS_PER_BYTE_MASKED(nr_bits)) {
                btf_int_bits_show(btf, t, safe_data, bits_offset, show);
                goto out;
        }

        switch (nr_bits) {
        case 128:
                btf_int128_print(show, safe_data);
                break;
        case 64:
                if (sign)
                        btf_show_type_value(show, "%lld", *(s64 *)safe_data);
                else
                        btf_show_type_value(show, "%llu", *(u64 *)safe_data);
                break;
        case 32:
                if (sign)
                        btf_show_type_value(show, "%d", *(s32 *)safe_data);
                else
                        btf_show_type_value(show, "%u", *(u32 *)safe_data);
                break;
        case 16:
                if (sign)
                        btf_show_type_value(show, "%d", *(s16 *)safe_data);
                else
                        btf_show_type_value(show, "%u", *(u16 *)safe_data);
                break;
        case 8:
                if (show->state.array_encoding == BTF_INT_CHAR) {
                        /* check for null terminator */
                        if (show->state.array_terminated)
                                break;
                        if (*(char *)data == '\0') {
                                show->state.array_terminated = 1;
                                break;
                        }
                        if (isprint(*(char *)data)) {
                                btf_show_type_value(show, "'%c'",
                                                    *(char *)safe_data);
                                break;
                        }
                }
                if (sign)
                        btf_show_type_value(show, "%d", *(s8 *)safe_data);
                else
                        btf_show_type_value(show, "%u", *(u8 *)safe_data);
                break;
        default:
                btf_int_bits_show(btf, t, safe_data, bits_offset, show);
                break;
        }
out:
        btf_show_end_type(show);
}

static const struct btf_kind_operations int_ops = {
        .check_meta = btf_int_check_meta,
        .resolve = btf_df_resolve,
        .check_member = btf_int_check_member,
        .check_kflag_member = btf_int_check_kflag_member,
        .log_details = btf_int_log,
        .show = btf_int_show,
};

static int btf_modifier_check_member(struct btf_verifier_env *env,
                                     const struct btf_type *struct_type,
                                     const struct btf_member *member,
                                     const struct btf_type *member_type)
{
        const struct btf_type *resolved_type;
        u32 resolved_type_id = member->type;
        struct btf_member resolved_member;
        struct btf *btf = env->btf;

        resolved_type = btf_type_id_size(btf, &resolved_type_id, NULL);
        if (!resolved_type) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Invalid member");
                return -EINVAL;
        }

        resolved_member = *member;
        resolved_member.type = resolved_type_id;

        return btf_type_ops(resolved_type)->check_member(env, struct_type,
                                                         &resolved_member,
                                                         resolved_type);
}

static int btf_modifier_check_kflag_member(struct btf_verifier_env *env,
                                           const struct btf_type *struct_type,
                                           const struct btf_member *member,
                                           const struct btf_type *member_type)
{
        const struct btf_type *resolved_type;
        u32 resolved_type_id = member->type;
        struct btf_member resolved_member;
        struct btf *btf = env->btf;

        resolved_type = btf_type_id_size(btf, &resolved_type_id, NULL);
        if (!resolved_type) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Invalid member");
                return -EINVAL;
        }

        resolved_member = *member;
        resolved_member.type = resolved_type_id;

        return btf_type_ops(resolved_type)->check_kflag_member(env, struct_type,
                                                               &resolved_member,
                                                               resolved_type);
}

static int btf_ptr_check_member(struct btf_verifier_env *env,
                                const struct btf_type *struct_type,
                                const struct btf_member *member,
                                const struct btf_type *member_type)
{
        u32 struct_size, struct_bits_off, bytes_offset;

        struct_size = struct_type->size;
        struct_bits_off = member->offset;
        bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);

        if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Member is not byte aligned");
                return -EINVAL;
        }

        if (struct_size - bytes_offset < sizeof(void *)) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Member exceeds struct_size");
                return -EINVAL;
        }

        return 0;
}

static int btf_ref_type_check_meta(struct btf_verifier_env *env,
                                   const struct btf_type *t,
                                   u32 meta_left)
{
        if (btf_type_vlen(t)) {
                btf_verifier_log_type(env, t, "vlen != 0");
                return -EINVAL;
        }

        if (btf_type_kflag(t)) {
                btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
                return -EINVAL;
        }

        if (!BTF_TYPE_ID_VALID(t->type)) {
                btf_verifier_log_type(env, t, "Invalid type_id");
                return -EINVAL;
        }

        /* typedef type must have a valid name, and other ref types,
         * volatile, const, restrict, should have a null name.
         */
        if (BTF_INFO_KIND(t->info) == BTF_KIND_TYPEDEF) {
                if (!t->name_off ||
                    !btf_name_valid_identifier(env->btf, t->name_off)) {
                        btf_verifier_log_type(env, t, "Invalid name");
                        return -EINVAL;
                }
        } else {
                if (t->name_off) {
                        btf_verifier_log_type(env, t, "Invalid name");
                        return -EINVAL;
                }
        }

        btf_verifier_log_type(env, t, NULL);

        return 0;
}

static int btf_modifier_resolve(struct btf_verifier_env *env,
                                const struct resolve_vertex *v)
{
        const struct btf_type *t = v->t;
        const struct btf_type *next_type;
        u32 next_type_id = t->type;
        struct btf *btf = env->btf;

        next_type = btf_type_by_id(btf, next_type_id);
        if (!next_type || btf_type_is_resolve_source_only(next_type)) {
                btf_verifier_log_type(env, v->t, "Invalid type_id");
                return -EINVAL;
        }

        if (!env_type_is_resolve_sink(env, next_type) &&
            !env_type_is_resolved(env, next_type_id))
                return env_stack_push(env, next_type, next_type_id);

        /* Figure out the resolved next_type_id with size.
         * They will be stored in the current modifier's
         * resolved_ids and resolved_sizes such that it can
         * save us a few type-following when we use it later (e.g. in
         * pretty print).
         */
        if (!btf_type_id_size(btf, &next_type_id, NULL)) {
                if (env_type_is_resolved(env, next_type_id))
                        next_type = btf_type_id_resolve(btf, &next_type_id);

                /* "typedef void new_void", "const void"...etc */
                if (!btf_type_is_void(next_type) &&
                    !btf_type_is_fwd(next_type) &&
                    !btf_type_is_func_proto(next_type)) {
                        btf_verifier_log_type(env, v->t, "Invalid type_id");
                        return -EINVAL;
                }
        }

        env_stack_pop_resolved(env, next_type_id, 0);

        return 0;
}

static int btf_var_resolve(struct btf_verifier_env *env,
                           const struct resolve_vertex *v)
{
        const struct btf_type *next_type;
        const struct btf_type *t = v->t;
        u32 next_type_id = t->type;
        struct btf *btf = env->btf;

        next_type = btf_type_by_id(btf, next_type_id);
        if (!next_type || btf_type_is_resolve_source_only(next_type)) {
                btf_verifier_log_type(env, v->t, "Invalid type_id");
                return -EINVAL;
        }

        if (!env_type_is_resolve_sink(env, next_type) &&
            !env_type_is_resolved(env, next_type_id))
                return env_stack_push(env, next_type, next_type_id);

        if (btf_type_is_modifier(next_type)) {
                const struct btf_type *resolved_type;
                u32 resolved_type_id;

                resolved_type_id = next_type_id;
                resolved_type = btf_type_id_resolve(btf, &resolved_type_id);

                if (btf_type_is_ptr(resolved_type) &&
                    !env_type_is_resolve_sink(env, resolved_type) &&
                    !env_type_is_resolved(env, resolved_type_id))
                        return env_stack_push(env, resolved_type,
                                              resolved_type_id);
        }

        /* We must resolve to something concrete at this point, no
         * forward types or similar that would resolve to size of
         * zero is allowed.
         */
        if (!btf_type_id_size(btf, &next_type_id, NULL)) {
                btf_verifier_log_type(env, v->t, "Invalid type_id");
                return -EINVAL;
        }

        env_stack_pop_resolved(env, next_type_id, 0);

        return 0;
}

static int btf_ptr_resolve(struct btf_verifier_env *env,
                           const struct resolve_vertex *v)
{
        const struct btf_type *next_type;
        const struct btf_type *t = v->t;
        u32 next_type_id = t->type;
        struct btf *btf = env->btf;

        next_type = btf_type_by_id(btf, next_type_id);
        if (!next_type || btf_type_is_resolve_source_only(next_type)) {
                btf_verifier_log_type(env, v->t, "Invalid type_id");
                return -EINVAL;
        }

        if (!env_type_is_resolve_sink(env, next_type) &&
            !env_type_is_resolved(env, next_type_id))
                return env_stack_push(env, next_type, next_type_id);

        /* If the modifier was RESOLVED during RESOLVE_STRUCT_OR_ARRAY,
         * the modifier may have stopped resolving when it was resolved
         * to a ptr (last-resolved-ptr).
         *
         * We now need to continue from the last-resolved-ptr to
         * ensure the last-resolved-ptr will not referring back to
         * the currenct ptr (t).
         */
        if (btf_type_is_modifier(next_type)) {
                const struct btf_type *resolved_type;
                u32 resolved_type_id;

                resolved_type_id = next_type_id;
                resolved_type = btf_type_id_resolve(btf, &resolved_type_id);

                if (btf_type_is_ptr(resolved_type) &&
                    !env_type_is_resolve_sink(env, resolved_type) &&
                    !env_type_is_resolved(env, resolved_type_id))
                        return env_stack_push(env, resolved_type,
                                              resolved_type_id);
        }

        if (!btf_type_id_size(btf, &next_type_id, NULL)) {
                if (env_type_is_resolved(env, next_type_id))
                        next_type = btf_type_id_resolve(btf, &next_type_id);

                if (!btf_type_is_void(next_type) &&
                    !btf_type_is_fwd(next_type) &&
                    !btf_type_is_func_proto(next_type)) {
                        btf_verifier_log_type(env, v->t, "Invalid type_id");
                        return -EINVAL;
                }
        }

        env_stack_pop_resolved(env, next_type_id, 0);

        return 0;
}

static void btf_modifier_show(const struct btf *btf,
                              const struct btf_type *t,
                              u32 type_id, void *data,
                              u8 bits_offset, struct btf_show *show)
{
        if (btf->resolved_ids)
                t = btf_type_id_resolve(btf, &type_id);
        else
                t = btf_type_skip_modifiers(btf, type_id, NULL);

        btf_type_ops(t)->show(btf, t, type_id, data, bits_offset, show);
}

static void btf_var_show(const struct btf *btf, const struct btf_type *t,
                         u32 type_id, void *data, u8 bits_offset,
                         struct btf_show *show)
{
        t = btf_type_id_resolve(btf, &type_id);

        btf_type_ops(t)->show(btf, t, type_id, data, bits_offset, show);
}

static void btf_ptr_show(const struct btf *btf, const struct btf_type *t,
                         u32 type_id, void *data, u8 bits_offset,
                         struct btf_show *show)
{
        void *safe_data;

        safe_data = btf_show_start_type(show, t, type_id, data);
        if (!safe_data)
                return;

        /* It is a hashed value unless BTF_SHOW_PTR_RAW is specified */
        if (show->flags & BTF_SHOW_PTR_RAW)
                btf_show_type_value(show, "0x%px", *(void **)safe_data);
        else
                btf_show_type_value(show, "0x%p", *(void **)safe_data);
        btf_show_end_type(show);
}

static void btf_ref_type_log(struct btf_verifier_env *env,
                             const struct btf_type *t)
{
        btf_verifier_log(env, "type_id=%u", t->type);
}

static struct btf_kind_operations modifier_ops = {
        .check_meta = btf_ref_type_check_meta,
        .resolve = btf_modifier_resolve,
        .check_member = btf_modifier_check_member,
        .check_kflag_member = btf_modifier_check_kflag_member,
        .log_details = btf_ref_type_log,
        .show = btf_modifier_show,
};

static struct btf_kind_operations ptr_ops = {
        .check_meta = btf_ref_type_check_meta,
        .resolve = btf_ptr_resolve,
        .check_member = btf_ptr_check_member,
        .check_kflag_member = btf_generic_check_kflag_member,
        .log_details = btf_ref_type_log,
        .show = btf_ptr_show,
};

static s32 btf_fwd_check_meta(struct btf_verifier_env *env,
                              const struct btf_type *t,
                              u32 meta_left)
{
        if (btf_type_vlen(t)) {
                btf_verifier_log_type(env, t, "vlen != 0");
                return -EINVAL;
        }

        if (t->type) {
                btf_verifier_log_type(env, t, "type != 0");
                return -EINVAL;
        }

        /* fwd type must have a valid name */
        if (!t->name_off ||
            !btf_name_valid_identifier(env->btf, t->name_off)) {
                btf_verifier_log_type(env, t, "Invalid name");
                return -EINVAL;
        }

        btf_verifier_log_type(env, t, NULL);

        return 0;
}

static void btf_fwd_type_log(struct btf_verifier_env *env,
                             const struct btf_type *t)
{
        btf_verifier_log(env, "%s", btf_type_kflag(t) ? "union" : "struct");
}

static struct btf_kind_operations fwd_ops = {
        .check_meta = btf_fwd_check_meta,
        .resolve = btf_df_resolve,
        .check_member = btf_df_check_member,
        .check_kflag_member = btf_df_check_kflag_member,
        .log_details = btf_fwd_type_log,
        .show = btf_df_show,
};

static int btf_array_check_member(struct btf_verifier_env *env,
                                  const struct btf_type *struct_type,
                                  const struct btf_member *member,
                                  const struct btf_type *member_type)
{
        u32 struct_bits_off = member->offset;
        u32 struct_size, bytes_offset;
        u32 array_type_id, array_size;
        struct btf *btf = env->btf;

        if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Member is not byte aligned");
                return -EINVAL;
        }

        array_type_id = member->type;
        btf_type_id_size(btf, &array_type_id, &array_size);
        struct_size = struct_type->size;
        bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
        if (struct_size - bytes_offset < array_size) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Member exceeds struct_size");
                return -EINVAL;
        }

        return 0;
}

static s32 btf_array_check_meta(struct btf_verifier_env *env,
                                const struct btf_type *t,
                                u32 meta_left)
{
        const struct btf_array *array = btf_type_array(t);
        u32 meta_needed = sizeof(*array);

        if (meta_left < meta_needed) {
                btf_verifier_log_basic(env, t,
                                       "meta_left:%u meta_needed:%u",
                                       meta_left, meta_needed);
                return -EINVAL;
        }

        /* array type should not have a name */
        if (t->name_off) {
                btf_verifier_log_type(env, t, "Invalid name");
                return -EINVAL;
        }

        if (btf_type_vlen(t)) {
                btf_verifier_log_type(env, t, "vlen != 0");
                return -EINVAL;
        }

        if (btf_type_kflag(t)) {
                btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
                return -EINVAL;
        }

        if (t->size) {
                btf_verifier_log_type(env, t, "size != 0");
                return -EINVAL;
        }

        /* Array elem type and index type cannot be in type void,
         * so !array->type and !array->index_type are not allowed.
         */
        if (!array->type || !BTF_TYPE_ID_VALID(array->type)) {
                btf_verifier_log_type(env, t, "Invalid elem");
                return -EINVAL;
        }

        if (!array->index_type || !BTF_TYPE_ID_VALID(array->index_type)) {
                btf_verifier_log_type(env, t, "Invalid index");
                return -EINVAL;
        }

        btf_verifier_log_type(env, t, NULL);

        return meta_needed;
}

static int btf_array_resolve(struct btf_verifier_env *env,
                             const struct resolve_vertex *v)
{
        const struct btf_array *array = btf_type_array(v->t);
        const struct btf_type *elem_type, *index_type;
        u32 elem_type_id, index_type_id;
        struct btf *btf = env->btf;
        u32 elem_size;

        /* Check array->index_type */
        index_type_id = array->index_type;
        index_type = btf_type_by_id(btf, index_type_id);
        if (btf_type_nosize_or_null(index_type) ||
            btf_type_is_resolve_source_only(index_type)) {
                btf_verifier_log_type(env, v->t, "Invalid index");
                return -EINVAL;
        }

        if (!env_type_is_resolve_sink(env, index_type) &&
            !env_type_is_resolved(env, index_type_id))
                return env_stack_push(env, index_type, index_type_id);

        index_type = btf_type_id_size(btf, &index_type_id, NULL);
        if (!index_type || !btf_type_is_int(index_type) ||
            !btf_type_int_is_regular(index_type)) {
                btf_verifier_log_type(env, v->t, "Invalid index");
                return -EINVAL;
        }

        /* Check array->type */
        elem_type_id = array->type;
        elem_type = btf_type_by_id(btf, elem_type_id);
        if (btf_type_nosize_or_null(elem_type) ||
            btf_type_is_resolve_source_only(elem_type)) {
                btf_verifier_log_type(env, v->t,
                                      "Invalid elem");
                return -EINVAL;
        }

        if (!env_type_is_resolve_sink(env, elem_type) &&
            !env_type_is_resolved(env, elem_type_id))
                return env_stack_push(env, elem_type, elem_type_id);

        elem_type = btf_type_id_size(btf, &elem_type_id, &elem_size);
        if (!elem_type) {
                btf_verifier_log_type(env, v->t, "Invalid elem");
                return -EINVAL;
        }

        if (btf_type_is_int(elem_type) && !btf_type_int_is_regular(elem_type)) {
                btf_verifier_log_type(env, v->t, "Invalid array of int");
                return -EINVAL;
        }

        if (array->nelems && elem_size > U32_MAX / array->nelems) {
                btf_verifier_log_type(env, v->t,
                                      "Array size overflows U32_MAX");
                return -EINVAL;
        }

        env_stack_pop_resolved(env, elem_type_id, elem_size * array->nelems);

        return 0;
}

static void btf_array_log(struct btf_verifier_env *env,
                          const struct btf_type *t)
{
        const struct btf_array *array = btf_type_array(t);

        btf_verifier_log(env, "type_id=%u index_type_id=%u nr_elems=%u",
                         array->type, array->index_type, array->nelems);
}

static void __btf_array_show(const struct btf *btf, const struct btf_type *t,
                             u32 type_id, void *data, u8 bits_offset,
                             struct btf_show *show)
{
        const struct btf_array *array = btf_type_array(t);
        const struct btf_kind_operations *elem_ops;
        const struct btf_type *elem_type;
        u32 i, elem_size = 0, elem_type_id;
        u16 encoding = 0;

        elem_type_id = array->type;
        elem_type = btf_type_skip_modifiers(btf, elem_type_id, NULL);
        if (elem_type && btf_type_has_size(elem_type))
                elem_size = elem_type->size;

        if (elem_type && btf_type_is_int(elem_type)) {
                u32 int_type = btf_type_int(elem_type);

                encoding = BTF_INT_ENCODING(int_type);

                /*
                 * BTF_INT_CHAR encoding never seems to be set for
                 * char arrays, so if size is 1 and element is
                 * printable as a char, we'll do that.
                 */
                if (elem_size == 1)
                        encoding = BTF_INT_CHAR;
        }

        if (!btf_show_start_array_type(show, t, type_id, encoding, data))
                return;

        if (!elem_type)
                goto out;
        elem_ops = btf_type_ops(elem_type);

        for (i = 0; i < array->nelems; i++) {

                btf_show_start_array_member(show);

                elem_ops->show(btf, elem_type, elem_type_id, data,
                               bits_offset, show);
                data += elem_size;

                btf_show_end_array_member(show);

                if (show->state.array_terminated)
                        break;
        }
out:
        btf_show_end_array_type(show);
}

static void btf_array_show(const struct btf *btf, const struct btf_type *t,
                           u32 type_id, void *data, u8 bits_offset,
                           struct btf_show *show)
{
        const struct btf_member *m = show->state.member;

        /*
         * First check if any members would be shown (are non-zero).
         * See comments above "struct btf_show" definition for more
         * details on how this works at a high-level.
         */
        if (show->state.depth > 0 && !(show->flags & BTF_SHOW_ZERO)) {
                if (!show->state.depth_check) {
                        show->state.depth_check = show->state.depth + 1;
                        show->state.depth_to_show = 0;
                }
                __btf_array_show(btf, t, type_id, data, bits_offset, show);
                show->state.member = m;

                if (show->state.depth_check != show->state.depth + 1)
                        return;
                show->state.depth_check = 0;

                if (show->state.depth_to_show <= show->state.depth)
                        return;
                /*
                 * Reaching here indicates we have recursed and found
                 * non-zero array member(s).
                 */
        }
        __btf_array_show(btf, t, type_id, data, bits_offset, show);
}

static struct btf_kind_operations array_ops = {
        .check_meta = btf_array_check_meta,
        .resolve = btf_array_resolve,
        .check_member = btf_array_check_member,
        .check_kflag_member = btf_generic_check_kflag_member,
        .log_details = btf_array_log,
        .show = btf_array_show,
};

static int btf_struct_check_member(struct btf_verifier_env *env,
                                   const struct btf_type *struct_type,
                                   const struct btf_member *member,
                                   const struct btf_type *member_type)
{
        u32 struct_bits_off = member->offset;
        u32 struct_size, bytes_offset;

        if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Member is not byte aligned");
                return -EINVAL;
        }

        struct_size = struct_type->size;
        bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
        if (struct_size - bytes_offset < member_type->size) {
                btf_verifier_log_member(env, struct_type, member,
                                        "Member exceeds struct_size");
                return -EINVAL;
        }

        return 0;
}

static s32 btf_struct_check_meta(struct btf_verifier_env *env,
                                 const struct btf_type *t,
                                 u32 meta_left)
{
        bool is_union = BTF_INFO_KIND(t->info) == BTF_KIND_UNION;
        const struct btf_member *member;
        u32 meta_needed, last_offset;
        struct btf *btf = env->btf;
        u32 struct_size = t->size;
        u32 offset;
        u16 i;

        meta_needed = btf_type_vlen(t) * sizeof(*member);
        if (meta_left < meta_needed) {
                btf_verifier_log_basic(env, t,
                                       "meta_left:%u meta_needed:%u",
                                       meta_left, meta_needed);
                return -EINVAL;
        }

        /* struct type either no name or a valid one */
        if (t->name_off &&
            !btf_name_valid_identifier(env->btf, t->name_off)) {
                btf_verifier_log_type(env, t, "Invalid name");
                return -EINVAL;
        }

        btf_verifier_log_type(env, t, NULL);

        last_offset = 0;
        for_each_member(i, t, member) {
                if (!btf_name_offset_valid(btf, member->name_off)) {
                        btf_verifier_log_member(env, t, member,
                                                "Invalid member name_offset:%u",
                                                member->name_off);
                        return -EINVAL;
                }

                /* struct member either no name or a valid one */
                if (member->name_off &&
                    !btf_name_valid_identifier(btf, member->name_off)) {
                        btf_verifier_log_member(env, t, member, "Invalid name");
                        return -EINVAL;
                }
                /* A member cannot be in type void */
                if (!member->type || !BTF_TYPE_ID_VALID(member->type)) {
                        btf_verifier_log_member(env, t, member,
                                                "Invalid type_id");
                        return -EINVAL;
                }

                offset = btf_member_bit_offset(t, member);
                if (is_union && offset) {
                        btf_verifier_log_member(env, t, member,
                                                "Invalid member bits_offset");
                        return -EINVAL;
                }

                /*
                 * ">" instead of ">=" because the last member could be
                 * "char a[0];"
                 */
                if (last_offset > offset) {
                        btf_verifier_log_member(env, t, member,
                                                "Invalid member bits_offset");
                        return -EINVAL;
                }

                if (BITS_ROUNDUP_BYTES(offset) > struct_size) {
                        btf_verifier_log_member(env, t, member,
                                                "Member bits_offset exceeds its struct size");
                        return -EINVAL;
                }

                btf_verifier_log_member(env, t, member, NULL);
                last_offset = offset;
        }

        return meta_needed;
}

static int btf_struct_resolve(struct btf_verifier_env *env,
                              const struct resolve_vertex *v)
{
        const struct btf_member *member;
        int err;
        u16 i;

        /* Before continue resolving the next_member,
         * ensure the last member is indeed resolved to a
         * type with size info.
         */
        if (v->next_member) {
                const struct btf_type *last_member_type;
                const struct btf_member *last_member;
                u16 last_member_type_id;

                last_member = btf_type_member(v->t) + v->next_member - 1;
                last_member_type_id = last_member->type;
                if (WARN_ON_ONCE(!env_type_is_resolved(env,
                                                       last_member_type_id)))
                        return -EINVAL;

                last_member_type = btf_type_by_id(env->btf,
                                                  last_member_type_id);
                if (btf_type_kflag(v->t))
                        err = btf_type_ops(last_member_type)->check_kflag_member(env, v->t,
                                                                last_member,
                                                                last_member_type);
                else
                        err = btf_type_ops(last_member_type)->check_member(env, v->t,
                                                                last_member,
                                                                last_member_type);
                if (err)
                        return err;
        }

        for_each_member_from(i, v->next_member, v->t, member) {
                u32 member_type_id = member->type;
                const struct btf_type *member_type = btf_type_by_id(env->btf,
                                                                member_type_id);

                if (btf_type_nosize_or_null(member_type) ||
                    btf_type_is_resolve_source_only(member_type)) {
                        btf_verifier_log_member(env, v->t, member,
                                                "Invalid member");
                        return -EINVAL;
                }

                if (!env_type_is_resolve_sink(env, member_type) &&
                    !env_type_is_resolved(env, member_type_id)) {
                        env_stack_set_next_member(env, i + 1);
                        return env_stack_push(env, member_type, member_type_id);
                }

                if (btf_type_kflag(v->t))
                        err = btf_type_ops(member_type)->check_kflag_member(env, v->t,
                                                                            member,
                                                                            member_type);
                else
                        err = btf_type_ops(member_type)->check_member(env, v->t,
                                                                      member,
                                                                      member_type);
                if (err)
                        return err;
        }

        env_stack_pop_resolved(env, 0, 0);

        return 0;
}

static void btf_struct_log(struct btf_verifier_env *env,
                           const struct btf_type *t)
{
        btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t));
}

/* find 'struct bpf_spin_lock' in map value.
 * return >= 0 offset if found
 * and < 0 in case of error
 */
int btf_find_spin_lock(const struct btf *btf, const struct btf_type *t)
{
        const struct btf_member *member;
        u32 i, off = -ENOENT;

        if (!__btf_type_is_struct(t))
                return -EINVAL;

        for_each_member(i, t, member) {
                const struct btf_type *member_type = btf_type_by_id(btf,
                                                                    member->type);
                if (!__btf_type_is_struct(member_type))
                        continue;
                if (member_type->size != sizeof(struct bpf_spin_lock))
                        continue;
                if (strcmp(__btf_name_by_offset(btf, member_type->name_off),
                           "bpf_spin_lock"))
                        continue;