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69b693f0ae
This patch introduces BPF type Format (BTF). 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. The first use case is to provide a generic pretty print capability for a BPF map. BTF has its root from CTF (Compact C-Type format). To simplify the handling of BTF data, BTF removes the differences between small and big type/struct-member. Hence, BTF consistently uses u32 instead of supporting both "one u16" and "two u32 (+padding)" in describing type and struct-member. It also raises the number of types (and functions) limit from 0x7fff to 0x7fffffff. Due to the above changes, the format is not compatible to CTF. Hence, BTF starts with a new BTF_MAGIC and version number. This patch does the first verification pass to the BTF. The first pass checks: 1. meta-data size (e.g. It does not go beyond the total btf's size) 2. name_offset is valid 3. Each BTF_KIND (e.g. int, enum, struct....) does its own check of its meta-data. Some other checks, like checking a struct's member is referring to a valid type, can only be done in the second pass. The second verification pass will be implemented in the next patch. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Acked-by: Alexei Starovoitov <ast@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
131 lines
3.6 KiB
C
131 lines
3.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
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/* Copyright (c) 2018 Facebook */
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#ifndef _UAPI__LINUX_BTF_H__
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#define _UAPI__LINUX_BTF_H__
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#include <linux/types.h>
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#define BTF_MAGIC 0xeB9F
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#define BTF_MAGIC_SWAP 0x9FeB
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#define BTF_VERSION 1
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#define BTF_FLAGS_COMPR 0x01
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struct btf_header {
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__u16 magic;
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__u8 version;
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__u8 flags;
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__u32 parent_label;
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__u32 parent_name;
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/* All offsets are in bytes relative to the end of this header */
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__u32 label_off; /* offset of label section */
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__u32 object_off; /* offset of data object section*/
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__u32 func_off; /* offset of function section */
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__u32 type_off; /* offset of type section */
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__u32 str_off; /* offset of string section */
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__u32 str_len; /* length of string section */
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};
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/* Max # of type identifier */
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#define BTF_MAX_TYPE 0x7fffffff
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/* Max offset into the string section */
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#define BTF_MAX_NAME_OFFSET 0x7fffffff
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/* Max # of struct/union/enum members or func args */
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#define BTF_MAX_VLEN 0xffff
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/* The type id is referring to a parent BTF */
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#define BTF_TYPE_PARENT(id) (((id) >> 31) & 0x1)
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#define BTF_TYPE_ID(id) ((id) & BTF_MAX_TYPE)
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/* String is in the ELF string section */
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#define BTF_STR_TBL_ELF_ID(ref) (((ref) >> 31) & 0x1)
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#define BTF_STR_OFFSET(ref) ((ref) & BTF_MAX_NAME_OFFSET)
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struct btf_type {
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__u32 name;
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/* "info" bits arrangement
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* bits 0-15: vlen (e.g. # of struct's members)
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* bits 16-23: unused
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* bits 24-28: kind (e.g. int, ptr, array...etc)
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* bits 29-30: unused
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* bits 31: root
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*/
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__u32 info;
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/* "size" is used by INT, ENUM, STRUCT and UNION.
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* "size" tells the size of the type it is describing.
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*
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* "type" is used by PTR, TYPEDEF, VOLATILE, CONST and RESTRICT.
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* "type" is a type_id referring to another type.
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*/
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union {
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__u32 size;
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__u32 type;
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};
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};
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#define BTF_INFO_KIND(info) (((info) >> 24) & 0x1f)
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#define BTF_INFO_ISROOT(info) (!!(((info) >> 24) & 0x80))
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#define BTF_INFO_VLEN(info) ((info) & 0xffff)
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#define BTF_KIND_UNKN 0 /* Unknown */
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#define BTF_KIND_INT 1 /* Integer */
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#define BTF_KIND_PTR 2 /* Pointer */
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#define BTF_KIND_ARRAY 3 /* Array */
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#define BTF_KIND_STRUCT 4 /* Struct */
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#define BTF_KIND_UNION 5 /* Union */
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#define BTF_KIND_ENUM 6 /* Enumeration */
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#define BTF_KIND_FWD 7 /* Forward */
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#define BTF_KIND_TYPEDEF 8 /* Typedef */
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#define BTF_KIND_VOLATILE 9 /* Volatile */
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#define BTF_KIND_CONST 10 /* Const */
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#define BTF_KIND_RESTRICT 11 /* Restrict */
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#define BTF_KIND_MAX 11
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#define NR_BTF_KINDS 12
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/* For some specific BTF_KIND, "struct btf_type" is immediately
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* followed by extra data.
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*/
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/* BTF_KIND_INT is followed by a u32 and the following
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* is the 32 bits arrangement:
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*/
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#define BTF_INT_ENCODING(VAL) (((VAL) & 0xff000000) >> 24)
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#define BTF_INT_OFFSET(VAL) (((VAL & 0x00ff0000)) >> 16)
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#define BTF_INT_BITS(VAL) ((VAL) & 0x0000ffff)
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/* Attributes stored in the BTF_INT_ENCODING */
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#define BTF_INT_SIGNED 0x1
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#define BTF_INT_CHAR 0x2
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#define BTF_INT_BOOL 0x4
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#define BTF_INT_VARARGS 0x8
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/* BTF_KIND_ENUM is followed by multiple "struct btf_enum".
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* The exact number of btf_enum is stored in the vlen (of the
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* info in "struct btf_type").
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*/
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struct btf_enum {
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__u32 name;
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__s32 val;
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};
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/* BTF_KIND_ARRAY is followed by one "struct btf_array" */
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struct btf_array {
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__u32 type;
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__u32 index_type;
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__u32 nelems;
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};
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/* BTF_KIND_STRUCT and BTF_KIND_UNION are followed
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* by multiple "struct btf_member". The exact number
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* of btf_member is stored in the vlen (of the info in
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* "struct btf_type").
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*/
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struct btf_member {
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__u32 name;
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__u32 type;
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__u32 offset; /* offset in bits */
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};
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#endif /* _UAPI__LINUX_BTF_H__ */
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