// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
/* Copyright (c) 2021 Facebook */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <linux/filter.h>
#include <sys/param.h>
#include "btf.h"
#include "bpf.h"
#include "libbpf.h"
#include "libbpf_internal.h"
#include "hashmap.h"
#include "bpf_gen_internal.h"
#include "skel_internal.h"
#include <asm/byteorder.h>

#define MAX_USED_MAPS   64
#define MAX_USED_PROGS  32
#define MAX_KFUNC_DESCS 256
#define MAX_FD_ARRAY_SZ (MAX_USED_MAPS + MAX_KFUNC_DESCS)

/* The following structure describes the stack layout of the loader program.
 * In addition R6 contains the pointer to context.
 * R7 contains the result of the last sys_bpf command (typically error or FD).
 * R9 contains the result of the last sys_close command.
 *
 * Naming convention:
 * ctx - bpf program context
 * stack - bpf program stack
 * blob - bpf_attr-s, strings, insns, map data.
 *        All the bytes that loader prog will use for read/write.
 */
struct loader_stack {
        __u32 btf_fd;
        __u32 inner_map_fd;
        __u32 prog_fd[MAX_USED_PROGS];
};

#define stack_off(field) \
        (__s16)(-sizeof(struct loader_stack) + offsetof(struct loader_stack, field))

#define attr_field(attr, field) (attr + offsetof(union bpf_attr, field))

static int blob_fd_array_off(struct bpf_gen *gen, int index)
{
        return gen->fd_array + index * sizeof(int);
}

static int realloc_insn_buf(struct bpf_gen *gen, __u32 size)
{
        size_t off = gen->insn_cur - gen->insn_start;
        void *insn_start;

        if (gen->error)
                return gen->error;
        if (size > INT32_MAX || off + size > INT32_MAX) {
                gen->error = -ERANGE;
                return -ERANGE;
        }
        insn_start = realloc(gen->insn_start, off + size);
        if (!insn_start) {
                gen->error = -ENOMEM;
                free(gen->insn_start);
                gen->insn_start = NULL;
                return -ENOMEM;
        }
        gen->insn_start = insn_start;
        gen->insn_cur = insn_start + off;
        return 0;
}

static int realloc_data_buf(struct bpf_gen *gen, __u32 size)
{
        size_t off = gen->data_cur - gen->data_start;
        void *data_start;

        if (gen->error)
                return gen->error;
        if (size > INT32_MAX || off + size > INT32_MAX) {
                gen->error = -ERANGE;
                return -ERANGE;
        }
        data_start = realloc(gen->data_start, off + size);
        if (!data_start) {
                gen->error = -ENOMEM;
                free(gen->data_start);
                gen->data_start = NULL;
                return -ENOMEM;
        }
        gen->data_start = data_start;
        gen->data_cur = data_start + off;
        return 0;
}

static void emit(struct bpf_gen *gen, struct bpf_insn insn)
{
        if (realloc_insn_buf(gen, sizeof(insn)))
                return;
        memcpy(gen->insn_cur, &insn, sizeof(insn));
        gen->insn_cur += sizeof(insn);
}

static void emit2(struct bpf_gen *gen, struct bpf_insn insn1, struct bpf_insn insn2)
{
        emit(gen, insn1);
        emit(gen, insn2);
}

static int add_data(struct bpf_gen *gen, const void *data, __u32 size);
static void emit_sys_close_blob(struct bpf_gen *gen, int blob_off);

void bpf_gen__init(struct bpf_gen *gen, int log_level, int nr_progs, int nr_maps)
{
        size_t stack_sz = sizeof(struct loader_stack), nr_progs_sz;
        int i;

        gen->fd_array = add_data(gen, NULL, MAX_FD_ARRAY_SZ * sizeof(int));
        gen->log_level = log_level;
        /* save ctx pointer into R6 */
        emit(gen, BPF_MOV64_REG(BPF_REG_6, BPF_REG_1));

        /* bzero stack */
        emit(gen, BPF_MOV64_REG(BPF_REG_1, BPF_REG_10));
        emit(gen, BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -stack_sz));
        emit(gen, BPF_MOV64_IMM(BPF_REG_2, stack_sz));
        emit(gen, BPF_MOV64_IMM(BPF_REG_3, 0));
        emit(gen, BPF_EMIT_CALL(BPF_FUNC_probe_read_kernel));

        /* amount of stack actually used, only used to calculate iterations, not stack offset */
        nr_progs_sz = offsetof(struct loader_stack, prog_fd[nr_progs]);
        /* jump over cleanup code */
        emit(gen, BPF_JMP_IMM(BPF_JA, 0, 0,
                              /* size of cleanup code below (including map fd cleanup) */
                              (nr_progs_sz / 4) * 3 + 2 +
                              /* 6 insns for emit_sys_close_blob,
                               * 6 insns for debug_regs in emit_sys_close_blob
                               */
                              nr_maps * (6 + (gen->log_level ? 6 : 0))));

        /* remember the label where all error branches will jump to */
        gen->cleanup_label = gen->insn_cur - gen->insn_start;
        /* emit cleanup code: close all temp FDs */
        for (i = 0; i < nr_progs_sz; i += 4) {
                emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_10, -stack_sz + i));
                emit(gen, BPF_JMP_IMM(BPF_JSLE, BPF_REG_1, 0, 1));
                emit(gen, BPF_EMIT_CALL(BPF_FUNC_sys_close));
        }
        for (i = 0; i < nr_maps; i++)
                emit_sys_close_blob(gen, blob_fd_array_off(gen, i));
        /* R7 contains the error code from sys_bpf. Copy it into R0 and exit. */
        emit(gen, BPF_MOV64_REG(BPF_REG_0, BPF_REG_7));
        emit(gen, BPF_EXIT_INSN());
}

static int add_data(struct bpf_gen *gen, const void *data, __u32 size)
{
        __u32 size8 = roundup(size, 8);
        __u64 zero = 0;
        void *prev;

        if (realloc_data_buf(gen, size8))
                return 0;
        prev = gen->data_cur;
        if (data) {
                memcpy(gen->data_cur, data, size);
                memcpy(gen->data_cur + size, &zero, size8 - size);
        } else {
                memset(gen->data_cur, 0, size8);
        }
        gen->data_cur += size8;
        return prev - gen->data_start;
}

/* Get index for map_fd/btf_fd slot in reserved fd_array, or in data relative
 * to start of fd_array. Caller can decide if it is usable or not.
 */
static int add_map_fd(struct bpf_gen *gen)
{
        if (gen->nr_maps == MAX_USED_MAPS) {
                pr_warn("Total maps exceeds %d\n", MAX_USED_MAPS);
                gen->error = -E2BIG;
                return 0;
        }
        return gen->nr_maps++;
}

static int add_kfunc_btf_fd(struct bpf_gen *gen)
{
        int cur;

        if (gen->nr_fd_array == MAX_KFUNC_DESCS) {
                cur = add_data(gen, NULL, sizeof(int));
                return (cur - gen->fd_array) / sizeof(int);
        }
        return MAX_USED_MAPS + gen->nr_fd_array++;
}

static int insn_bytes_to_bpf_size(__u32 sz)
{
        switch (sz) {
        case 8: return BPF_DW;
        case 4: return BPF_W;
        case 2: return BPF_H;
        case 1: return BPF_B;
        default: return -1;
        }
}

/* *(u64 *)(blob + off) = (u64)(void *)(blob + data) */
static void emit_rel_store(struct bpf_gen *gen, int off, int data)
{
        emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_0, BPF_PSEUDO_MAP_IDX_VALUE,
                                         0, 0, 0, data));
        emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
                                         0, 0, 0, off));
        emit(gen, BPF_STX_MEM(BPF_DW, BPF_REG_1, BPF_REG_0, 0));
}

static void move_blob2blob(struct bpf_gen *gen, int off, int size, int blob_off)
{
        emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_2, BPF_PSEUDO_MAP_IDX_VALUE,
                                         0, 0, 0, blob_off));
        emit(gen, BPF_LDX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_0, BPF_REG_2, 0));
        emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
                                         0, 0, 0, off));
        emit(gen, BPF_STX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_1, BPF_REG_0, 0));
}

static void move_blob2ctx(struct bpf_gen *gen, int ctx_off, int size, int blob_off)
{
        emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
                                         0, 0, 0, blob_off));
        emit(gen, BPF_LDX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_0, BPF_REG_1, 0));
        emit(gen, BPF_STX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_6, BPF_REG_0, ctx_off));
}

static void move_ctx2blob(struct bpf_gen *gen, int off, int size, int ctx_off,
                                   bool check_non_zero)
{
        emit(gen, BPF_LDX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_0, BPF_REG_6, ctx_off));
        if (check_non_zero)
                /* If value in ctx is zero don't update the blob.
                 * For example: when ctx->map.max_entries == 0, keep default max_entries from bpf.c
                 */
                emit(gen, BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 3));
        emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
                                         0, 0, 0, off));
        emit(gen, BPF_STX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_1, BPF_REG_0, 0));
}

static void move_stack2blob(struct bpf_gen *gen, int off, int size, int stack_off)
{
        emit(gen, BPF_LDX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_0, BPF_REG_10, stack_off));
        emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
                                         0, 0, 0, off));
        emit(gen, BPF_STX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_1, BPF_REG_0, 0));
}

static void move_stack2ctx(struct bpf_gen *gen, int ctx_off, int size, int stack_off)
{
        emit(gen, BPF_LDX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_0, BPF_REG_10, stack_off));
        emit(gen, BPF_STX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_6, BPF_REG_0, ctx_off));
}

static void emit_sys_bpf(struct bpf_gen *gen, int cmd, int attr, int attr_size)
{
        emit(gen, BPF_MOV64_IMM(BPF_REG_1, cmd));
        emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_2, BPF_PSEUDO_MAP_IDX_VALUE,
                                         0, 0, 0, attr));
        emit(gen, BPF_MOV64_IMM(BPF_REG_3, attr_size));
        emit(gen, BPF_EMIT_CALL(BPF_FUNC_sys_bpf));
        /* remember the result in R7 */
        emit(gen, BPF_MOV64_REG(BPF_REG_7, BPF_REG_0));
}

static bool is_simm16(__s64 value)
{
        return value == (__s64)(__s16)value;
}

static void emit_check_err(struct bpf_gen *gen)
{
        __s64 off = -(gen->insn_cur - gen->insn_start - gen->cleanup_label) / 8 - 1;

        /* R7 contains result of last sys_bpf command.
         * if (R7 < 0) goto cleanup;
         */
        if (is_simm16(off)) {
                emit(gen, BPF_JMP_IMM(BPF_JSLT, BPF_REG_7, 0, off));
        } else {
                gen->error = -ERANGE;
                emit(gen, BPF_JMP_IMM(BPF_JA, 0, 0, -1));
        }
}

/* reg1 and reg2 should not be R1 - R5. They can be R0, R6 - R10 */
static void emit_debug(struct bpf_gen *gen, int reg1, int reg2,
                       const char *fmt, va_list args)
{
        char buf[1024];
        int addr, len, ret;

        if (!gen->log_level)
                return;
        ret = vsnprintf(buf, sizeof(buf), fmt, args);
        if (ret < 1024 - 7 && reg1 >= 0 && reg2 < 0)
                /* The special case to accommodate common debug_ret():
                 * to avoid specifying BPF_REG_7 and adding " r=%%d" to
                 * prints explicitly.
                 */
                strcat(buf, " r=%d");
        len = strlen(buf) + 1;
        addr = add_data(gen, buf, len);

        emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
                                         0, 0, 0, addr));
        emit(gen, BPF_MOV64_IMM(BPF_REG_2, len));
        if (reg1 >= 0)
                emit(gen, BPF_MOV64_REG(BPF_REG_3, reg1));
        if (reg2 >= 0)
                emit(gen, BPF_MOV64_REG(BPF_REG_4, reg2));
        emit(gen, BPF_EMIT_CALL(BPF_FUNC_trace_printk));
}

static void debug_regs(struct bpf_gen *gen, int reg1, int reg2, const char *fmt, ...)
{
        va_list args;

        va_start(args, fmt);
        emit_debug(gen, reg1, reg2, fmt, args);
        va_end(args);
}

static void debug_ret(struct bpf_gen *gen, const char *fmt, ...)
{
        va_list args;

        va_start(args, fmt);
        emit_debug(gen, BPF_REG_7, -1, fmt, args);
        va_end(args);
}

static void __emit_sys_close(struct bpf_gen *gen)
{
        emit(gen, BPF_JMP_IMM(BPF_JSLE, BPF_REG_1, 0,
                              /* 2 is the number of the following insns
                               * * 6 is additional insns in debug_regs
                               */
                              2 + (gen->log_level ? 6 : 0)));
        emit(gen, BPF_MOV64_REG(BPF_REG_9, BPF_REG_1));
        emit(gen, BPF_EMIT_CALL(BPF_FUNC_sys_close));
        debug_regs(gen, BPF_REG_9, BPF_REG_0, "close(%%d) = %%d");
}

static void emit_sys_close_stack(struct bpf_gen *gen, int stack_off)
{
        emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_10, stack_off));
        __emit_sys_close(gen);
}

static void emit_sys_close_blob(struct bpf_gen *gen, int blob_off)
{
        emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_0, BPF_PSEUDO_MAP_IDX_VALUE,
                                         0, 0, 0, blob_off));
        emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_0, 0));
        __emit_sys_close(gen);
}

int bpf_gen__finish(struct bpf_gen *gen, int nr_progs, int nr_maps)
{
        int i;

        if (nr_progs < gen->nr_progs || nr_maps != gen->nr_maps) {
                pr_warn("nr_progs %d/%d nr_maps %d/%d mismatch\n",
                        nr_progs, gen->nr_progs, nr_maps, gen->nr_maps);
                gen->error = -EFAULT;
                return gen->error;
        }
        emit_sys_close_stack(gen, stack_off(btf_fd));
        for (i = 0; i < gen->nr_progs; i++)
                move_stack2ctx(gen,
                               sizeof(struct bpf_loader_ctx) +
                               sizeof(struct bpf_map_desc) * gen->nr_maps +
                               sizeof(struct bpf_prog_desc) * i +
                               offsetof(struct bpf_prog_desc, prog_fd), 4,
                               stack_off(prog_fd[i]));
        for (i = 0; i < gen->nr_maps; i++)
                move_blob2ctx(gen,
                              sizeof(struct bpf_loader_ctx) +
                              sizeof(struct bpf_map_desc) * i +
                              offsetof(struct bpf_map_desc, map_fd), 4,
                              blob_fd_array_off(gen, i));
        emit(gen, BPF_MOV64_IMM(BPF_REG_0, 0));
        emit(gen, BPF_EXIT_INSN());
        pr_debug("gen: finish %d\n", gen->error);
        if (!gen->error) {
                struct gen_loader_opts *opts = gen->opts;

                opts->insns = gen->insn_start;
                opts->insns_sz = gen->insn_cur - gen->insn_start;
                opts->data = gen->data_start;
                opts->data_sz = gen->data_cur - gen->data_start;
        }
        return gen->error;
}

void bpf_gen__free(struct bpf_gen *gen)
{
        if (!gen)
                return;
        free(gen->data_start);
        free(gen->insn_start);
        free(gen);
}

void bpf_gen__load_btf(struct bpf_gen *gen, const void *btf_raw_data,
                       __u32 btf_raw_size)
{
        int attr_size = offsetofend(union bpf_attr, btf_log_level);
        int btf_data, btf_load_attr;
        union bpf_attr attr;

        memset(&attr, 0, attr_size);
        pr_debug("gen: load_btf: size %d\n", btf_raw_size);
        btf_data = add_data(gen, btf_raw_data, btf_raw_size);

        attr.btf_size = btf_raw_size;
        btf_load_attr = add_data(gen, &attr, attr_size);

        /* populate union bpf_attr with user provided log details */
        move_ctx2blob(gen, attr_field(btf_load_attr, btf_log_level), 4,
                      offsetof(struct bpf_loader_ctx, log_level), false);
        move_ctx2blob(gen, attr_field(btf_load_attr, btf_log_size), 4,
                      offsetof(struct bpf_loader_ctx, log_size), false);
        move_ctx2blob(gen, attr_field(btf_load_attr, btf_log_buf), 8,
                      offsetof(struct bpf_loader_ctx, log_buf), false);
        /* populate union bpf_attr with a pointer to the BTF data */
        emit_rel_store(gen, attr_field(btf_load_attr, btf), btf_data);
        /* emit BTF_LOAD command */
        emit_sys_bpf(gen, BPF_BTF_LOAD, btf_load_attr, attr_size);
        debug_ret(gen, "btf_load size %d", btf_raw_size);
        emit_check_err(gen);
        /* remember btf_fd in the stack, if successful */
        emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_7, stack_off(btf_fd)));
}

void bpf_gen__map_create(struct bpf_gen *gen,
                         enum bpf_map_type map_type,
                         const char *map_name,
                         __u32 key_size, __u32 value_size, __u32 max_entries,
                         struct bpf_map_create_opts *map_attr, int map_idx)
{
        int attr_size = offsetofend(union bpf_attr, map_extra);
        bool close_inner_map_fd = false;
        int map_create_attr, idx;
        union bpf_attr attr;

        memset(&attr, 0, attr_size);
        attr.map_type = map_type;
        attr.key_size = key_size;
        attr.value_size = value_size;
        attr.map_flags = map_attr->map_flags;
        attr.map_extra = map_attr->map_extra;
        if (map_name)
                libbpf_strlcpy(attr.map_name, map_name, sizeof(attr.map_name));
        attr.numa_node = map_attr->numa_node;
        attr.map_ifindex = map_attr->map_ifindex;
        attr.max_entries = max_entries;
        attr.btf_key_type_id = map_attr->btf_key_type_id;
        attr.btf_value_type_id = map_attr->btf_value_type_id;

        pr_debug("gen: map_create: %s idx %d type %d value_type_id %d\n",
                 attr.map_name, map_idx, map_type, attr.btf_value_type_id);

        map_create_attr = add_data(gen, &attr, attr_size);
        if (attr.btf_value_type_id)
                /* populate union bpf_attr with btf_fd saved in the stack earlier */
                move_stack2blob(gen, attr_field(map_create_attr, btf_fd), 4,
                                stack_off(btf_fd));
        switch (attr.map_type) {
        case BPF_MAP_TYPE_ARRAY_OF_MAPS:
        case BPF_MAP_TYPE_HASH_OF_MAPS:
                move_stack2blob(gen, attr_field(map_create_attr, inner_map_fd), 4,
                                stack_off(inner_map_fd));
                close_inner_map_fd = true;
                break;
        default:
                break;
        }
        /* conditionally update max_entries */
        if (map_idx >= 0)
                move_ctx2blob(gen, attr_field(map_create_attr, max_entries), 4,
                              sizeof(struct bpf_loader_ctx) +
                              sizeof(struct bpf_map_desc) * map_idx +
                              offsetof(struct bpf_map_desc, max_entries),
                              true /* check that max_entries != 0 */);
        /* emit MAP_CREATE command */
        emit_sys_bpf(gen, BPF_MAP_CREATE, map_create_attr, attr_size);
        debug_ret(gen, "map_create %s idx %d type %d value_size %d value_btf_id %d",
                  attr.map_name, map_idx, map_type, value_size,
                  attr.btf_value_type_id);
        emit_check_err(gen);
        /* remember map_fd in the stack, if successful */
        if (map_idx < 0) {
                /* This bpf_gen__map_create() function is called with map_idx >= 0
                 * for all maps that libbpf loading logic tracks.
                 * It's called with -1 to create an inner map.
                 */
                emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_7,
                                      stack_off(inner_map_fd)));
        } else if (map_idx != gen->nr_maps) {
                gen->error = -EDOM; /* internal bug */
                return;
        } else {
                /* add_map_fd does gen->nr_maps++ */
                idx = add_map_fd(gen);
                emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
                                                 0, 0, 0, blob_fd_array_off(gen, idx)));
                emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_7, 0));
        }
        if (close_inner_map_fd)
                emit_sys_close_stack(gen, stack_off(inner_map_fd));
}

void bpf_gen__record_attach_target(struct bpf_gen *gen, const char *attach_name,
                                   enum bpf_attach_type type)
{
        const char *prefix;
        int kind, ret;

        btf_get_kernel_prefix_kind(type, &prefix, &kind);
        gen->attach_kind = kind;
        ret = snprintf(gen->attach_target, sizeof(gen->attach_target), "%s%s",
                       prefix, attach_name);
        if (ret == sizeof(gen->attach_target))
                gen->error = -ENOSPC;
}

static void emit_find_attach_target(struct bpf_gen *gen)
{
        int name, len = strlen(gen->attach_target) + 1;

        pr_debug("gen: find_attach_tgt %s %d\n", gen->attach_target, gen->attach_kind);
        name = add_data(gen, gen->attach_target, len);

        emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
                                         0, 0, 0, name));
        emit(gen, BPF_MOV64_IMM(BPF_REG_2, len));
        emit(gen, BPF_MOV64_IMM(BPF_REG_3, gen->attach_kind));
        emit(gen, BPF_MOV64_IMM(BPF_REG_4, 0));
        emit(gen, BPF_EMIT_CALL(BPF_FUNC_btf_find_by_name_kind));
        emit(gen, BPF_MOV64_REG(BPF_REG_7, BPF_REG_0));
        debug_ret(gen, "find_by_name_kind(%s,%d)",
                  gen->attach_target, gen->attach_kind);
        emit_check_err(gen);
        /* if successful, btf_id is in lower 32-bit of R7 and
         * btf_obj_fd is in upper 32-bit
         */
}

void bpf_gen__record_extern(struct bpf_gen *gen, const char *name, bool is_weak,
                            bool is_typeless, int kind, int insn_idx)
{
        struct ksym_relo_desc *relo;

        relo = libbpf_reallocarray(gen->relos, gen->relo_cnt + 1, sizeof(*relo));
        if (!relo) {
                gen->error = -ENOMEM;
                return;
        }
        gen->relos = relo;
        relo += gen->relo_cnt;
        relo->name = name;
        relo->is_weak = is_weak;
        relo->is_typeless = is_typeless;
        relo->kind = kind;
        relo->insn_idx = insn_idx;
        gen->relo_cnt++;
}

/* returns existing ksym_desc with ref incremented, or inserts a new one */
static struct ksym_desc *get_ksym_desc(struct bpf_gen *gen, struct ksym_relo_desc *relo)
{
        struct ksym_desc *kdesc;
        int i;

        for (i = 0; i < gen->nr_ksyms; i++) {
                if (!strcmp(gen->ksyms[i].name, relo->name)) {
                        gen->ksyms[i].ref++;
                        return &gen->ksyms[i];
                }
        }
        kdesc = libbpf_reallocarray(gen->ksyms, gen->nr_ksyms + 1, sizeof(*kdesc));
        if (!kdesc) {
                gen->error = -ENOMEM;
                return NULL;
        }
        gen->ksyms = kdesc;
        kdesc = &gen->ksyms[gen->nr_ksyms++];
        kdesc->name = relo->name;
        kdesc->kind = relo->kind;
        kdesc->ref = 1;
        kdesc->off = 0;
        kdesc->insn = 0;
        return kdesc;
}

/* Overwrites BPF_REG_{0, 1, 2, 3, 4, 7}
 * Returns result in BPF_REG_7
 */
static void emit_bpf_find_by_name_kind(struct bpf_gen *gen, struct ksym_relo_desc *relo)
{
        int name_off, len = strlen(relo->name) + 1;

        name_off = add_data(gen, relo->name, len);
        emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
                                         0, 0, 0, name_off));
        emit(gen, BPF_MOV64_IMM(BPF_REG_2, len));
        emit(gen, BPF_MOV64_IMM(BPF_REG_3, relo->kind));
        emit(gen, BPF_MOV64_IMM(BPF_REG_4, 0));
        emit(gen, BPF_EMIT_CALL(BPF_FUNC_btf_find_by_name_kind));
        emit(gen, BPF_MOV64_REG(BPF_REG_7, BPF_REG_0));
        debug_ret(gen, "find_by_name_kind(%s,%d)", relo->name, relo->kind);
}

/* Overwrites BPF_REG_{0, 1, 2, 3, 4, 7}
 * Returns result in BPF_REG_7
 * Returns u64 symbol addr in BPF_REG_9
 */
static void emit_bpf_kallsyms_lookup_name(struct bpf_gen *gen, struct ksym_relo_desc *relo)
{
        int name_off, len = strlen(relo->name) + 1, res_off;

        name_off = add_data(gen, relo->name, len);
        res_off = add_data(gen, NULL, 8); /* res is u64 */
        emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
                                         0, 0, 0, name_off));
        emit(gen, BPF_MOV64_IMM(BPF_REG_2, len));
        emit(gen, BPF_MOV64_IMM(BPF_REG_3, 0));
        emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_4, BPF_PSEUDO_MAP_IDX_VALUE,
                                         0, 0, 0, res_off));
        emit(gen, BPF_MOV64_REG(BPF_REG_7, BPF_REG_4));
        emit(gen, BPF_EMIT_CALL(BPF_FUNC_kallsyms_lookup_name));
        emit(gen, BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0));
        emit(gen, BPF_MOV64_REG(BPF_REG_7, BPF_REG_0));
        debug_ret(gen, "kallsyms_lookup_name(%s,%d)", relo->name, relo->kind);
}

/* Expects:
 * BPF_REG_8 - pointer to instruction
 *
 * We need to reuse BTF fd for same symbol otherwise each relocation takes a new
 * index, while kernel limits total kfunc BTFs to 256. For duplicate symbols,
 * this would mean a new BTF fd index for each entry. By pairing symbol name
 * with index, we get the insn->imm, insn->off pairing that kernel uses for
 * kfunc_tab, which becomes the effective limit even though all of them may
 * share same index in fd_array (such that kfunc_btf_tab has 1 element).
 */
static void emit_relo_kfunc_btf(struct bpf_gen *gen, struct ksym_relo_desc *relo, int insn)
{
        struct ksym_desc *kdesc;
        int btf_fd_idx;

        kdesc = get_ksym_desc(gen, relo);
        if (!kdesc)
                return;
        /* try to copy from existing bpf_insn */
        if (kdesc->ref > 1) {
                move_blob2blob(gen, insn + offsetof(struct bpf_insn, imm), 4,
                               kdesc->insn + offsetof(struct bpf_insn, imm));
                move_blob2blob(gen, insn + offsetof(struct bpf_insn, off), 2,
                               kdesc->insn + offsetof(struct bpf_insn, off));
                goto log;
        }
        /* remember insn offset, so we can copy BTF ID and FD later */
        kdesc->insn = insn;
        emit_bpf_find_by_name_kind(gen, relo);
        if (!relo->is_weak)
                emit_check_err(gen);
        /* get index in fd_array to store BTF FD at */
        btf_fd_idx = add_kfunc_btf_fd(gen);
        if (btf_fd_idx > INT16_MAX) {
                pr_warn("BTF fd off %d for kfunc %s exceeds INT16_MAX, cannot process relocation\n",
                        btf_fd_idx, relo->name);
                gen->error = -E2BIG;
                return;
        }
        kdesc->off = btf_fd_idx;
        /* jump to success case */
        emit(gen, BPF_JMP_IMM(BPF_JSGE, BPF_REG_7, 0, 3));
        /* set value for imm, off as 0 */
        emit(gen, BPF_ST_MEM(BPF_W, BPF_REG_8, offsetof(struct bpf_insn, imm), 0));
        emit(gen, BPF_ST_MEM(BPF_H, BPF_REG_8, offsetof(struct bpf_insn, off), 0));
        /* skip success case for ret < 0 */
        emit(gen, BPF_JMP_IMM(BPF_JA, 0, 0, 10));
        /* store btf_id into insn[insn_idx].imm */
        emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_8, BPF_REG_7, offsetof(struct bpf_insn, imm)));
        /* obtain fd in BPF_REG_9 */
        emit(gen, BPF_MOV64_REG(BPF_REG_9, BPF_REG_7));
        emit(gen, BPF_ALU64_IMM(BPF_RSH, BPF_REG_9, 32));
        /* jump to fd_array store if fd denotes module BTF */
        emit(gen, BPF_JMP_IMM(BPF_JNE, BPF_REG_9, 0, 2));
        /* set the default value for off */
        emit(gen, BPF_ST_MEM(BPF_H, BPF_REG_8, offsetof(struct bpf_insn, off), 0));
        /* skip BTF fd store for vmlinux BTF */
        emit(gen, BPF_JMP_IMM(BPF_JA, 0, 0, 4));
        /* load fd_array slot pointer */
        emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_0, BPF_PSEUDO_MAP_IDX_VALUE,
                                         0, 0, 0, blob_fd_array_off(gen, btf_fd_idx)));
        /* store BTF fd in slot */
        emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_0, BPF_REG_9, 0));
        /* store index into insn[insn_idx].off */
        emit(gen, BPF_ST_MEM(BPF_H, BPF_REG_8, offsetof(struct bpf_insn, off), btf_fd_idx));
log:
        if (!gen->log_level)
                return;
        emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_8,
                              offsetof(struct bpf_insn, imm)));
        emit(gen, BPF_LDX_MEM(BPF_H, BPF_REG_9, BPF_REG_8,
                              offsetof(struct bpf_insn, off)));
        debug_regs(gen, BPF_REG_7, BPF_REG_9, " func (%s:count=%d): imm: %%d, off: %%d",
                   relo->name, kdesc->ref);
        emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_0, BPF_PSEUDO_MAP_IDX_VALUE,
                                         0, 0, 0, blob_fd_array_off(gen, kdesc->off)));
        emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_9, BPF_REG_0, 0));
        debug_regs(gen, BPF_REG_9, -1, " func (%s:count=%d): btf_fd",
                   relo->name, kdesc->ref);
}

static void emit_ksym_relo_log(struct bpf_gen *gen, struct ksym_relo_desc *relo,
                               int ref)
{
        if (!gen->log_level)
                return;
        emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_8,
                              offsetof(struct bpf_insn, imm)));
        emit(gen, BPF_LDX_MEM(BPF_H, BPF_REG_9, BPF_REG_8, sizeof(struct bpf_insn) +
                              offsetof(struct bpf_insn, imm)));
        debug_regs(gen, BPF_REG_7, BPF_REG_9, " var t=%d w=%d (%s:count=%d): imm[0]: %%d, imm[1]: %%d",
                   relo->is_typeless, relo->is_weak, relo->name, ref);
        emit(gen, BPF_LDX_MEM(BPF_B, BPF_REG_9, BPF_REG_8, offsetofend(struct bpf_insn, code)));
        debug_regs(gen, BPF_REG_9, -1, " var t=%d w=%d (%s:count=%d): insn.reg",
                   relo->is_typeless, relo->is_weak, relo->name, ref);
}

/* Expects:
 * BPF_REG_8 - pointer to instruction
 */
static void emit_relo_ksym_typeless(struct bpf_gen *gen,
                                    struct ksym_relo_desc *relo, int insn)
{
        struct ksym_desc *kdesc;

        kdesc = get_ksym_desc(gen, relo);
        if (!kdesc)
                return;
        /* try to copy from existing ldimm64 insn */
        if (kdesc->ref > 1) {
                move_blob2blob(gen, insn + offsetof(struct bpf_insn, imm), 4,
                               kdesc->insn + offsetof(struct bpf_insn, imm));
                move_blob2blob(gen, insn + sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm), 4,
                               kdesc->insn + sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm));
                goto log;
        }
        /* remember insn offset, so we can copy ksym addr later */
        kdesc->insn = insn;
        /* skip typeless ksym_desc in fd closing loop in cleanup_relos */
        kdesc->typeless = true;
        emit_bpf_kallsyms_lookup_name(gen, relo);
        emit(gen, BPF_JMP_IMM(BPF_JEQ, BPF_REG_7, -ENOENT, 1));
        emit_check_err(gen);
        /* store lower half of addr into insn[insn_idx].imm */
        emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_8, BPF_REG_9, offsetof(struct bpf_insn, imm)));
        /* store upper half of addr into insn[insn_idx + 1].imm */
        emit(gen, BPF_ALU64_IMM(BPF_RSH, BPF_REG_9, 32));
        emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_8, BPF_REG_9,
                      sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm)));
log:
        emit_ksym_relo_log(gen, relo, kdesc->ref);
}

static __u32 src_reg_mask(void)
{
#if defined(__LITTLE_ENDIAN_BITFIELD)
        return 0x0f; /* src_reg,dst_reg,... */
#elif defined(__BIG_ENDIAN_BITFIELD)
        return 0xf0; /* dst_reg,src_reg,... */
#else
#error "Unsupported bit endianness, cannot proceed"
#endif
}

/* Expects:
 * BPF_REG_8 - pointer to instruction
 */
static void emit_relo_ksym_btf(struct bpf_gen *gen, struct ksym_relo_desc *relo, int insn)
{
        struct ksym_desc *kdesc;
        __u32 reg_mask;

        kdesc = get_ksym_desc(gen, relo);
        if (!kdesc)
                return;
        /* try to copy from existing ldimm64 insn */
        if (kdesc->ref > 1) {
                move_blob2blob(gen, insn + offsetof(struct bpf_insn, imm), 4,
                               kdesc->insn + offsetof(struct bpf_insn, imm));
                move_blob2blob(gen, insn + sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm), 4,
                               kdesc->insn + sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm));
                /* jump over src_reg adjustment if imm is not 0, reuse BPF_REG_0 from move_blob2blob */
                emit(gen, BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 3));
                goto clear_src_reg;
        }
        /* remember insn offset, so we can copy BTF ID and FD later */
        kdesc->insn = insn;
        emit_bpf_find_by_name_kind(gen, relo);
        if (!relo->is_weak)
                emit_check_err(gen);
        /* jump to success case */
        emit(gen, BPF_JMP_IMM(BPF_JSGE, BPF_REG_7, 0, 3));
        /* set values for insn[insn_idx].imm, insn[insn_idx + 1].imm as 0 */
        emit(gen, BPF_ST_MEM(BPF_W, BPF_REG_8, offsetof(struct bpf_insn, imm), 0));
        emit(gen, BPF_ST_MEM(BPF_W, BPF_REG_8, sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm), 0));
        /* skip success case for ret < 0 */
        emit(gen, BPF_JMP_IMM(BPF_JA, 0, 0, 4));
        /* store btf_id into insn[insn_idx].imm */
        emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_8, BPF_REG_7, offsetof(struct bpf_insn, imm)));
        /* store btf_obj_fd into insn[insn_idx + 1].imm */
        emit(gen, BPF_ALU64_IMM(BPF_RSH, BPF_REG_7, 32));
        emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_8, BPF_REG_7,
                              sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm)));
        /* skip src_reg adjustment */
        emit(gen, BPF_JMP_IMM(BPF_JSGE, BPF_REG_7, 0, 3));
clear_src_reg:
        /* clear bpf_object__relocate_data's src_reg assignment, otherwise we get a verifier failure */
        reg_mask = src_reg_mask();
        emit(gen, BPF_LDX_MEM(BPF_B, BPF_REG_9, BPF_REG_8, offsetofend(struct bpf_insn, code)));
        emit(gen, BPF_ALU32_IMM(BPF_AND, BPF_REG_9, reg_mask));
        emit(gen, BPF_STX_MEM(BPF_B, BPF_REG_8, BPF_REG_9, offsetofend(struct bpf_insn, code)));

        emit_ksym_relo_log(gen, relo, kdesc->ref);
}

void bpf_gen__record_relo_core(struct bpf_gen *gen,
                               const struct bpf_core_relo *core_relo)
{
        struct bpf_core_relo *relos;

        relos = libbpf_reallocarray(gen->core_relos, gen->core_relo_cnt + 1, sizeof(*relos));
        if (!relos) {
                gen->error = -ENOMEM;
                return;
        }
        gen->core_relos = relos;
        relos += gen->core_relo_cnt;
        memcpy(relos, core_relo, sizeof(*relos));
        gen->core_relo_cnt++;
}

static void emit_relo(struct bpf_gen *gen, struct ksym_relo_desc *relo, int insns)
{
        int insn;

        pr_debug("gen: emit_relo (%d): %s at %d\n", relo->kind, relo->name, relo->insn_idx);
        insn = insns + sizeof(struct bpf_insn) * relo->insn_idx;
        emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_8, BPF_PSEUDO_MAP_IDX_VALUE, 0, 0, 0, insn));
        switch (relo->kind) {
        case BTF_KIND_VAR:
                if (relo->is_typeless)
                        emit_relo_ksym_typeless(gen, relo, insn);
                else
                        emit_relo_ksym_btf(gen, relo, insn);
                break;
        case BTF_KIND_FUNC:
                emit_relo_kfunc_btf(gen, relo, insn);
                break;
        default:
                pr_warn("Unknown relocation kind '%d'\n", relo->kind);
                gen->error = -EDOM;
                return;
        }
}

static void emit_relos(struct bpf_gen *gen, int insns)
{
        int i;

        for (i = 0; i < gen->relo_cnt; i++)
                emit_relo(gen, gen->relos + i, insns);
}

static void cleanup_core_relo(struct bpf_gen *gen)
{
        if (!gen->core_relo_cnt)
                return;
        free(gen->core_relos);
        gen->core_relo_cnt = 0;
        gen->core_relos = NULL;
}

static void cleanup_relos(struct bpf_gen *gen, int insns)
{
        int i, insn;

        for (i = 0; i < gen->nr_ksyms; i++) {
                /* only close fds for typed ksyms and kfuncs */
                if (gen->ksyms[i].kind == BTF_KIND_VAR && !gen->ksyms[i].typeless) {
                        /* close fd recorded in insn[insn_idx + 1].imm */
                        insn = gen->ksyms[i].insn;
                        insn += sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm);
                        emit_sys_close_blob(gen, insn);
                } else if (gen->ksyms[i].kind == BTF_KIND_FUNC) {
                        emit_sys_close_blob(gen, blob_fd_array_off(gen, gen->ksyms[i].off));
                        if (gen->ksyms[i].off < MAX_FD_ARRAY_SZ)
                                gen->nr_fd_array--;
                }
        }
        if (gen->nr_ksyms) {
                free(gen->ksyms);
                gen->nr_ksyms = 0;
                gen->ksyms = NULL;
        }
        if (gen->relo_cnt) {
                free(gen->relos);
                gen->relo_cnt = 0;
                gen->relos = NULL;
        }
        cleanup_core_relo(gen);
}

void bpf_gen__prog_load(struct bpf_gen *gen,
                        enum bpf_prog_type prog_type, const char *prog_name,
                        const char *license, struct bpf_insn *insns, size_t insn_cnt,
                        struct bpf_prog_load_opts *load_attr, int prog_idx)
{
        int prog_load_attr, license_off, insns_off, func_info, line_info, core_relos;
        int attr_size = offsetofend(union bpf_attr, core_relo_rec_size);
        union bpf_attr attr;

        memset(&attr, 0, attr_size);
        pr_debug("gen: prog_load: type %d insns_cnt %zd progi_idx %d\n",
                 prog_type, insn_cnt, prog_idx);
        /* add license string to blob of bytes */
        license_off = add_data(gen, license, strlen(license) + 1);
        /* add insns to blob of bytes */
        insns_off = add_data(gen, insns, insn_cnt * sizeof(struct bpf_insn));

        attr.prog_type = prog_type;
        attr.expected_attach_type = load_attr->expected_attach_type;
        attr.attach_btf_id = load_attr->attach_btf_id;
        attr.prog_ifindex = load_attr->prog_ifindex;
        attr.kern_version = 0;
        attr.insn_cnt = (__u32)insn_cnt;
        attr.prog_flags = load_attr->prog_flags;

        attr.func_info_rec_size = load_attr->func_info_rec_size;
        attr.func_info_cnt = load_attr->func_info_cnt;
        func_info = add_data(gen, load_attr->func_info,
                             attr.func_info_cnt * attr.func_info_rec_size);

        attr.line_info_rec_size = load_attr->line_info_rec_size;
        attr.line_info_cnt = load_attr->line_info_cnt;
        line_info = add_data(gen, load_attr->line_info,
                             attr.line_info_cnt * attr.line_info_rec_size);

        attr.core_relo_rec_size = sizeof(struct bpf_core_relo);
        attr.core_relo_cnt = gen->core_relo_cnt;
        core_relos = add_data(gen, gen->core_relos,
                             attr.core_relo_cnt * attr.core_relo_rec_size);

        libbpf_strlcpy(attr.prog_name, prog_name, sizeof(attr.prog_name));
        prog_load_attr = add_data(gen, &attr, attr_size);

        /* populate union bpf_attr with a pointer to license */
        emit_rel_store(gen, attr_field(prog_load_attr, license), license_off);

        /* populate union bpf_attr with a pointer to instructions */
        emit_rel_store(gen, attr_field(prog_load_attr, insns), insns_off);

        /* populate union bpf_attr with a pointer to func_info */
        emit_rel_store(gen, attr_field(prog_load_attr, func_info), func_info);

        /* populate union bpf_attr with a pointer to line_info */
        emit_rel_store(gen, attr_field(prog_load_attr, line_info), line_info);

        /* populate union bpf_attr with a pointer to core_relos */
        emit_rel_store(gen, attr_field(prog_load_attr, core_relos), core_relos);

        /* populate union bpf_attr fd_array with a pointer to data where map_fds are saved */
        emit_rel_store(gen, attr_field(prog_load_attr, fd_array), gen->fd_array);

        /* populate union bpf_attr with user provided log details */
        move_ctx2blob(gen, attr_field(prog_load_attr, log_level), 4,
                      offsetof(struct bpf_loader_ctx, log_level), false);
        move_ctx2blob(gen, attr_field(prog_load_attr, log_size), 4,
                      offsetof(struct bpf_loader_ctx, log_size), false);
        move_ctx2blob(gen, attr_field(prog_load_attr, log_buf), 8,
                      offsetof(struct bpf_loader_ctx, log_buf), false);
        /* populate union bpf_attr with btf_fd saved in the stack earlier */

        move_stack2blob(gen, attr_field(prog_load_attr, prog_btf_fd), 4,
                        stack_off(btf_fd));
        if (gen->attach_kind) {
                emit_find_attach_target(gen);
                /* populate union bpf_attr with btf_id and btf_obj_fd found by helper */
                emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_0, BPF_PSEUDO_MAP_IDX_VALUE,
                                                 0, 0, 0, prog_load_attr));
                emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_0, BPF_REG_7,
                                      offsetof(union bpf_attr, attach_btf_id)));
                emit(gen, BPF_ALU64_IMM(BPF_RSH, BPF_REG_7, 32));
                emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_0, BPF_REG_7,
                                      offsetof(union bpf_attr, attach_btf_obj_fd)));
        }
        emit_relos(gen, insns_off);
        /* emit PROG_LOAD command */
        emit_sys_bpf(gen, BPF_PROG_LOAD, prog_load_attr, attr_size);
        debug_ret(gen, "prog_load %s insn_cnt %d", attr.prog_name, attr.insn_cnt);
        /* successful or not, close btf module FDs used in extern ksyms and attach_btf_obj_fd */
        cleanup_relos(gen, insns_off);
        if (gen->attach_kind) {
                emit_sys_close_blob(gen,
                                    attr_field(prog_load_attr, attach_btf_obj_fd));
                gen->attach_kind = 0;
        }
        emit_check_err(gen);
        /* remember prog_fd in the stack, if successful */
        emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_7,
                              stack_off(prog_fd[gen->nr_progs])));
        gen->nr_progs++;
}

void bpf_gen__map_update_elem(struct bpf_gen *gen, int map_idx, void *pvalue,
                              __u32 value_size)
{
        int attr_size = offsetofend(union bpf_attr, flags);
        int map_update_attr, value, key;
        union bpf_attr attr;
        int zero = 0;

        memset(&attr, 0, attr_size);
        pr_debug("gen: map_update_elem: idx %d\n", map_idx);

        value = add_data(gen, pvalue, value_size);
        key = add_data(gen, &zero, sizeof(zero));

        /* if (map_desc[map_idx].initial_value)
         *    copy_from_user(value, initial_value, value_size);
         */
        emit(gen, BPF_LDX_MEM(BPF_DW, BPF_REG_3, BPF_REG_6,
                              sizeof(struct bpf_loader_ctx) +
                              sizeof(struct bpf_map_desc) * map_idx +
                              offsetof(struct bpf_map_desc, initial_value)));
        emit(gen, BPF_JMP_IMM(BPF_JEQ, BPF_REG_3, 0, 4));
        emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
                                         0, 0, 0, value));
        emit(gen, BPF_MOV64_IMM(BPF_REG_2, value_size));
        emit(gen, BPF_EMIT_CALL(BPF_FUNC_copy_from_user));

        map_update_attr = add_data(gen, &attr, attr_size);
        move_blob2blob(gen, attr_field(map_update_attr, map_fd), 4,
                       blob_fd_array_off(gen, map_idx));
        emit_rel_store(gen, attr_field(map_update_attr, key), key);
        emit_rel_store(gen, attr_field(map_update_attr, value), value);
        /* emit MAP_UPDATE_ELEM command */
        emit_sys_bpf(gen, BPF_MAP_UPDATE_ELEM, map_update_attr, attr_size);
        debug_ret(gen, "update_elem idx %d value_size %d", map_idx, value_size);
        emit_check_err(gen);
}

void bpf_gen__populate_outer_map(struct bpf_gen *gen, int outer_map_idx, int slot,
                                 int inner_map_idx)
{
        int attr_size = offsetofend(union bpf_attr, flags);
        int map_update_attr, key;
        union bpf_attr attr;

        memset(&attr, 0, attr_size);
        pr_debug("gen: populate_outer_map: outer %d key %d inner %d\n",
                 outer_map_idx, slot, inner_map_idx);

        key = add_data(gen, &slot, sizeof(slot));

        map_update_attr = add_data(gen, &attr, attr_size);
        move_blob2blob(gen, attr_field(map_update_attr, map_fd), 4,
                       blob_fd_array_off(gen, outer_map_idx));
        emit_rel_store(gen, attr_field(map_update_attr, key), key);
        emit_rel_store(gen, attr_field(map_update_attr, value),
                       blob_fd_array_off(gen, inner_map_idx));

        /* emit MAP_UPDATE_ELEM command */
        emit_sys_bpf(gen, BPF_MAP_UPDATE_ELEM, map_update_attr, attr_size);
        debug_ret(gen, "populate_outer_map outer %d key %d inner %d",
                  outer_map_idx, slot, inner_map_idx);
        emit_check_err(gen);
}

void bpf_gen__map_freeze(struct bpf_gen *gen, int map_idx)
{
        int attr_size = offsetofend(union bpf_attr, map_fd);
        int map_freeze_attr;
        union bpf_attr attr;

        memset(&attr, 0, attr_size);
        pr_debug("gen: map_freeze: idx %d\n", map_idx);
        map_freeze_attr = add_data(gen, &attr, attr_size);
        move_blob2blob(gen, attr_field(map_freeze_attr, map_fd), 4,
                       blob_fd_array_off(gen, map_idx));
        /* emit MAP_FREEZE command */
        emit_sys_bpf(gen, BPF_MAP_FREEZE, map_freeze_attr, attr_size);
        debug_ret(gen, "map_freeze");
        emit_check_err(gen);
}