zig/lib/std/os/linux/bpf/btf.zig
2020-09-07 12:26:41 -07:00

157 lines
3.6 KiB
Zig

// SPDX-License-Identifier: MIT
// Copyright (c) 2015-2020 Zig Contributors
// This file is part of [zig](https://ziglang.org/), which is MIT licensed.
// The MIT license requires this copyright notice to be included in all copies
// and substantial portions of the software.
const magic = 0xeb9f;
const version = 1;
pub const ext = @import("ext.zig");
/// All offsets are in bytes relative to the end of this header
pub const Header = packed struct {
magic: u16,
version: u8,
flags: u8,
hdr_len: u32,
/// offset of type section
type_off: u32,
/// length of type section
type_len: u32,
/// offset of string section
str_off: u32,
/// length of string section
str_len: u32,
};
/// Max number of type identifiers
pub const max_type = 0xfffff;
/// Max offset into string section
pub const max_name_offset = 0xffffff;
/// Max number of struct/union/enum member of func args
pub const max_vlen = 0xffff;
pub const Type = packed struct {
name_off: u32,
info: packed struct {
/// number of struct's members
vlen: u16,
unused_1: u8,
kind: Kind,
unused_2: u3,
/// used by Struct, Union, and Fwd
kind_flag: bool,
},
/// size is used by Int, Enum, Struct, Union, and DataSec, it tells the size
/// of the type it is describing
///
/// type is used by Ptr, Typedef, Volatile, Const, Restrict, Func,
/// FuncProto, and Var. It is a type_id referring to another type
size_type: union { size: u32, typ: u32 },
};
/// For some kinds, Type is immediately followed by extra data
pub const Kind = enum(u4) {
unknown,
int,
ptr,
array,
structure,
kind_union,
enumeration,
fwd,
typedef,
kind_volatile,
constant,
restrict,
func,
funcProto,
variable,
dataSec,
};
/// Int kind is followed by this struct
pub const IntInfo = packed struct {
bits: u8,
unused: u8,
offset: u8,
encoding: enum(u4) {
signed = 1 << 0,
char = 1 << 1,
boolean = 1 << 2,
},
};
test "IntInfo is 32 bits" {
std.testing.expectEqual(@bitSizeOf(IntInfo), 32);
}
/// Enum kind is followed by this struct
pub const Enum = packed struct {
name_off: u32,
val: i32,
};
/// Array kind is followd by this struct
pub const Array = packed struct {
typ: u32,
index_type: u32,
nelems: u32,
};
/// Struct and Union kinds are followed by multiple Member structs. The exact
/// number is stored in vlen
pub const Member = packed struct {
name_off: u32,
typ: u32,
/// if the kind_flag is set, offset contains both member bitfield size and
/// bit offset, the bitfield size is set for bitfield members. If the type
/// info kind_flag is not set, the offset contains only bit offset
offset: packed struct {
bit: u24,
bitfield_size: u8,
},
};
/// FuncProto is followed by multiple Params, the exact number is stored in vlen
pub const Param = packed struct {
name_off: u32,
typ: u32,
};
pub const VarLinkage = enum {
static,
global_allocated,
global_extern,
};
pub const FuncLinkage = enum {
static,
global,
external,
};
/// Var kind is followd by a single Var struct to describe additional
/// information related to the variable such as its linkage
pub const Var = packed struct {
linkage: u32,
};
/// Datasec kind is followed by multible VarSecInfo to describe all Var kind
/// types it contains along with it's in-section offset as well as size.
pub const VarSecInfo = packed struct {
typ: u32,
offset: u32,
size: u32,
};