path: root/tools/bpf/bpftool/gen.c

// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
/* Copyright (C) 2019 Facebook */

#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <linux/err.h>
#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <bpf/bpf.h>
#include <bpf/libbpf.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <bpf/btf.h>
#include <bpf/bpf_gen_internal.h>

#include "json_writer.h"
#include "main.h"

#define MAX_OBJ_NAME_LEN 64

static void sanitize_identifier(char *name)
{
	int i;

	for (i = 0; name[i]; i++)
		if (!isalnum(name[i]) && name[i] != '_')
			name[i] = '_';
}

static bool str_has_suffix(const char *str, const char *suffix)
{
	size_t i, n1 = strlen(str), n2 = strlen(suffix);

	if (n1 < n2)
		return false;

	for (i = 0; i < n2; i++) {
		if (str[n1 - i - 1] != suffix[n2 - i - 1])
			return false;
	}

	return true;
}

static void get_obj_name(char *name, const char *file)
{
	/* Using basename() GNU version which doesn't modify arg. */
	strncpy(name, basename(file), MAX_OBJ_NAME_LEN - 1);
	name[MAX_OBJ_NAME_LEN - 1] = '\0';
	if (str_has_suffix(name, ".o"))
		name[strlen(name) - 2] = '\0';
	sanitize_identifier(name);
}

static void get_header_guard(char *guard, const char *obj_name)
{
	int i;

	sprintf(guard, "__%s_SKEL_H__", obj_name);
	for (i = 0; guard[i]; i++)
		guard[i] = toupper(guard[i]);
}

static const char *get_map_ident(const struct bpf_map *map)
{
	const char *name = bpf_map__name(map);

	if (!bpf_map__is_internal(map))
		return name;

	if (str_has_suffix(name, ".data"))
		return "data";
	else if (str_has_suffix(name, ".rodata"))
		return "rodata";
	else if (str_has_suffix(name, ".bss"))
		return "bss";
	else if (str_has_suffix(name, ".kconfig"))
		return "kconfig";
	else
		return NULL;
}

static void codegen_btf_dump_printf(void *ctx, const char *fmt, va_list args)
{
	vprintf(fmt, args);
}

static int codegen_datasec_def(struct bpf_object *obj,
			       struct btf *btf,
			       struct btf_dump *d,
			       const struct btf_type *sec,
			       const char *obj_name)
{
	const char *sec_name = btf__name_by_offset(btf, sec->name_off);
	const struct btf_var_secinfo *sec_var = btf_var_secinfos(sec);
	int i, err, off = 0, pad_cnt = 0, vlen = btf_vlen(sec);
	const char *sec_ident;
	char var_ident[256];
	bool strip_mods = false;

	if (strcmp(sec_name, ".data") == 0) {
		sec_ident = "data";
		strip_mods = true;
	} else if (strcmp(sec_name, ".bss") == 0) {
		sec_ident = "bss";
		strip_mods = true;
	} else if (strcmp(sec_name, ".rodata") == 0) {
		sec_ident = "rodata";
		strip_mods = true;
	} else if (strcmp(sec_name, ".kconfig") == 0) {
		sec_ident = "kconfig";
	} else {
		return 0;
	}

	printf("	struct %s__%s {\n", obj_name, sec_ident);
	for (i = 0; i < vlen; i++, sec_var++) {
		const struct btf_type *var = btf__type_by_id(btf, sec_var->type);
		const char *var_name = btf__name_by_offset(btf, var->name_off);
		DECLARE_LIBBPF_OPTS(btf_dump_emit_type_decl_opts, opts,
			.field_name = var_ident,
			.indent_level = 2,
			.strip_mods = strip_mods,
		);
		int need_off = sec_var->offset, align_off, align;
		__u32 var_type_id = var->type;

		/* static variables are not exposed through BPF skeleton */
		if (btf_var(var)->linkage == BTF_VAR_STATIC)
			continue;

		if (off > need_off) {
			p_err("Something is wrong for %s's variable #%d: need offset %d, already at %d.\n",
			      sec_name, i, need_off, off);
			return -EINVAL;
		}

		align = btf__align_of(btf, var->type</