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Commit 34df9d37 authored by Daniel Borkmann's avatar Daniel Borkmann
Browse files

Merge branch 'bpf-type-format' 

Martin KaFai Lau says:

====================
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.

A modified pahole that can convert dwarf to BTF is here:

  https://github.com/iamkafai/pahole/tree/btf



Please see individual patch for details.

v5:
- Remove BTF_KIND_FLOAT and BTF_KIND_FUNC which are not
  currently used.  They can be added in the future.
  Some bpf_df_xxx() are removed together.
- Add comment in patch 7 to clarify that the new bpffs_map_fops
  should not be extended further.

v4:
- Fix warning (remove unneeded semicolon)
- Remove a redundant variable (nr_bytes) from btf_int_check_meta() in
  patch 1.  Caught by W=1.

v3:
- Rebase to bpf-next
- Fix sparse warning (by adding static)
- Add BTF header logging: btf_verifier_log_hdr()
- Fix the alignment test on btf->type_off
- Add tests for the BTF header
- Lower the max BTF size to 16MB.  It should be enough
  for some time.  We could raise it later if it would
  be needed.

v2:
- Use kvfree where needed in patch 1 and 2
- Also consider BTF_INT_OFFSET() in the btf_int_check_meta()
  in patch 1
- Fix an incorrect goto target in map_create() during
  the btf-error-path in patch 7
- re-org some local vars to keep the rev xmas tree in btf.c
====================

Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parents 97e19cce c0fa1b6c

include/linux/bpf.h

+17 −3
Original line number Diff line number Diff line
@@ -22,6 +22,8 @@ struct perf_event; 
struct bpf_prog;

struct bpf_map;

struct sock;

struct seq_file;

struct btf;



/* map is generic key/value storage optionally accesible by eBPF programs */

struct bpf_map_ops {
@@ -43,10 +45,14 @@ struct bpf_map_ops { 
	void (*map_fd_put_ptr)(void *ptr);

	u32 (*map_gen_lookup)(struct bpf_map *map, struct bpf_insn *insn_buf);

	u32 (*map_fd_sys_lookup_elem)(void *ptr);

	void (*map_seq_show_elem)(struct bpf_map *map, void *key,

				  struct seq_file *m);

	int (*map_check_btf)(const struct bpf_map *map, const struct btf *btf,

			     u32 key_type_id, u32 value_type_id);

};



struct bpf_map {

	/* 1st cacheline with read-mostly members of which some

	/* The first two cachelines with read-mostly members of which some

	 * are also accessed in fast-path (e.g. ops, max_entries).

	 */

	const struct bpf_map_ops *ops ____cacheline_aligned;
@@ -62,10 +68,13 @@ struct bpf_map { 
	u32 pages;

	u32 id;

	int numa_node;

	u32 btf_key_id;

	u32 btf_value_id;

	struct btf *btf;

	bool unpriv_array;

	/* 7 bytes hole */

	/* 55 bytes hole */



	/* 2nd cacheline with misc members to avoid false sharing

	/* The 3rd and 4th cacheline with misc members to avoid false sharing

	 * particularly with refcounting.

	 */

	struct user_struct *user ____cacheline_aligned;
@@ -100,6 +109,11 @@ static inline struct bpf_offloaded_map *map_to_offmap(struct bpf_map *map) 
	return container_of(map, struct bpf_offloaded_map, map);

}



static inline bool bpf_map_support_seq_show(const struct bpf_map *map)

{

	return map->ops->map_seq_show_elem && map->ops->map_check_btf;

}



extern const struct bpf_map_ops bpf_map_offload_ops;



/* function argument constraints */

include/linux/btf.h

0 → 100644
+48 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

/* Copyright (c) 2018 Facebook */



#ifndef _LINUX_BTF_H

#define _LINUX_BTF_H 1



#include <linux/types.h>



struct btf;

struct btf_type;

union bpf_attr;



extern const struct file_operations btf_fops;



void btf_put(struct btf *btf);

int btf_new_fd(const union bpf_attr *attr);

struct btf *btf_get_by_fd(int fd);

int btf_get_info_by_fd(const struct btf *btf,

		       const union bpf_attr *attr,

		       union bpf_attr __user *uattr);

/* Figure out the size of a type_id.  If type_id is a modifier

 * (e.g. const), it will be resolved to find out the type with size.

 *

 * For example:

 * In describing "const void *",  type_id is "const" and "const"

 * refers to "void *".  The return type will be "void *".

 *

 * If type_id is a simple "int", then return type will be "int".

 *

 * @btf: struct btf object

 * @type_id: Find out the size of type_id. The type_id of the return

 *           type is set to *type_id.

 * @ret_size: It can be NULL.  If not NULL, the size of the return

 *            type is set to *ret_size.

 * Return: The btf_type (resolved to another type with size info if needed).

 *         NULL is returned if type_id itself does not have size info

 *         (e.g. void) or it cannot be resolved to another type that

 *         has size info.

 *         *type_id and *ret_size will not be changed in the

 *         NULL return case.

 */

const struct btf_type *btf_type_id_size(const struct btf *btf,

					u32 *type_id,

					u32 *ret_size);

void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj,

		       struct seq_file *m);



#endif

include/uapi/linux/bpf.h

+12 −0
Original line number Diff line number Diff line
@@ -95,6 +95,7 @@ enum bpf_cmd { 
	BPF_OBJ_GET_INFO_BY_FD,

	BPF_PROG_QUERY,

	BPF_RAW_TRACEPOINT_OPEN,

	BPF_BTF_LOAD,

};



enum bpf_map_type {
@@ -279,6 +280,9 @@ union bpf_attr { 
					 */

		char	map_name[BPF_OBJ_NAME_LEN];

		__u32	map_ifindex;	/* ifindex of netdev to create on */

		__u32	btf_fd;		/* fd pointing to a BTF type data */

		__u32	btf_key_id;	/* BTF type_id of the key */

		__u32	btf_value_id;	/* BTF type_id of the value */

	};



	struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */
@@ -363,6 +367,14 @@ union bpf_attr { 
		__u64 name;

		__u32 prog_fd;

	} raw_tracepoint;



	struct { /* anonymous struct for BPF_BTF_LOAD */

		__aligned_u64	btf;

		__aligned_u64	btf_log_buf;

		__u32		btf_size;

		__u32		btf_log_size;

		__u32		btf_log_level;

	};

} __attribute__((aligned(8)));



/* BPF helper function descriptions:

include/uapi/linux/btf.h

0 → 100644
+130 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */

/* Copyright (c) 2018 Facebook */

#ifndef _UAPI__LINUX_BTF_H__

#define _UAPI__LINUX_BTF_H__



#include <linux/types.h>



#define BTF_MAGIC	0xeB9F

#define BTF_MAGIC_SWAP	0x9FeB

#define BTF_VERSION	1

#define BTF_FLAGS_COMPR	0x01



struct btf_header {

	__u16	magic;

	__u8	version;

	__u8	flags;



	__u32	parent_label;

	__u32	parent_name;



	/* All offsets are in bytes relative to the end of this header */

	__u32	label_off;	/* offset of label section	*/

	__u32	object_off;	/* offset of data object section*/

	__u32	func_off;	/* offset of function section	*/

	__u32	type_off;	/* offset of type section	*/

	__u32	str_off;	/* offset of string section	*/

	__u32	str_len;	/* length of string section	*/

};



/* Max # of type identifier */

#define BTF_MAX_TYPE	0x7fffffff

/* Max offset into the string section */

#define BTF_MAX_NAME_OFFSET	0x7fffffff

/* Max # of struct/union/enum members or func args */

#define BTF_MAX_VLEN	0xffff



/* The type id is referring to a parent BTF */

#define BTF_TYPE_PARENT(id)	(((id) >> 31) & 0x1)

#define BTF_TYPE_ID(id)		((id) & BTF_MAX_TYPE)



/* String is in the ELF string section */

#define BTF_STR_TBL_ELF_ID(ref)	(((ref) >> 31) & 0x1)

#define BTF_STR_OFFSET(ref)	((ref) & BTF_MAX_NAME_OFFSET)



struct btf_type {

	__u32 name;

	/* "info" bits arrangement

	 * bits  0-15: vlen (e.g. # of struct's members)

	 * bits 16-23: unused

	 * bits 24-28: kind (e.g. int, ptr, array...etc)

	 * bits 29-30: unused

	 * bits    31: root

	 */

	__u32 info;

	/* "size" is used by INT, ENUM, STRUCT and UNION.

	 * "size" tells the size of the type it is describing.

	 *

	 * "type" is used by PTR, TYPEDEF, VOLATILE, CONST and RESTRICT.

	 * "type" is a type_id referring to another type.

	 */

	union {

		__u32 size;

		__u32 type;

	};

};



#define BTF_INFO_KIND(info)	(((info) >> 24) & 0x1f)

#define BTF_INFO_ISROOT(info)	(!!(((info) >> 24) & 0x80))

#define BTF_INFO_VLEN(info)	((info) & 0xffff)



#define BTF_KIND_UNKN		0	/* Unknown	*/

#define BTF_KIND_INT		1	/* Integer	*/

#define BTF_KIND_PTR		2	/* Pointer	*/

#define BTF_KIND_ARRAY		3	/* Array	*/

#define BTF_KIND_STRUCT		4	/* Struct	*/

#define BTF_KIND_UNION		5	/* Union	*/

#define BTF_KIND_ENUM		6	/* Enumeration	*/

#define BTF_KIND_FWD		7	/* Forward	*/

#define BTF_KIND_TYPEDEF	8	/* Typedef	*/

#define BTF_KIND_VOLATILE	9	/* Volatile	*/

#define BTF_KIND_CONST		10	/* Const	*/

#define BTF_KIND_RESTRICT	11	/* Restrict	*/

#define BTF_KIND_MAX		11

#define NR_BTF_KINDS		12



/* For some specific BTF_KIND, "struct btf_type" is immediately

 * followed by extra data.

 */



/* BTF_KIND_INT is followed by a u32 and the following

 * is the 32 bits arrangement:

 */

#define BTF_INT_ENCODING(VAL)	(((VAL) & 0xff000000) >> 24)

#define BTF_INT_OFFSET(VAL)	(((VAL  & 0x00ff0000)) >> 16)

#define BTF_INT_BITS(VAL)	((VAL)  & 0x0000ffff)



/* Attributes stored in the BTF_INT_ENCODING */

#define BTF_INT_SIGNED	0x1

#define BTF_INT_CHAR	0x2

#define BTF_INT_BOOL	0x4

#define BTF_INT_VARARGS	0x8



/* BTF_KIND_ENUM is followed by multiple "struct btf_enum".

 * The exact number of btf_enum is stored in the vlen (of the

 * info in "struct btf_type").

 */

struct btf_enum {

	__u32	name;

	__s32	val;

};



/* BTF_KIND_ARRAY is followed by one "struct btf_array" */

struct btf_array {

	__u32	type;

	__u32	index_type;

	__u32	nelems;

};



/* BTF_KIND_STRUCT and BTF_KIND_UNION are followed

 * by multiple "struct btf_member".  The exact number

 * of btf_member is stored in the vlen (of the info in

 * "struct btf_type").

 */

struct btf_member {

	__u32	name;

	__u32	type;

	__u32	offset;	/* offset in bits */

};



#endif /* _UAPI__LINUX_BTF_H__ */

kernel/bpf/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ obj-y := core.o 
obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o inode.o helpers.o tnum.o

obj-$(CONFIG_BPF_SYSCALL) += hashtab.o arraymap.o percpu_freelist.o bpf_lru_list.o lpm_trie.o map_in_map.o

obj-$(CONFIG_BPF_SYSCALL) += disasm.o

obj-$(CONFIG_BPF_SYSCALL) += btf.o

ifeq ($(CONFIG_NET),y)

obj-$(CONFIG_BPF_SYSCALL) += devmap.o

obj-$(CONFIG_BPF_SYSCALL) += cpumap.o