Commit 8fca4f98 authored by Alexei Starovoitov's avatar Alexei Starovoitov
Browse files

Merge branch 'bpf_iter-BTF_ID-at-build-time' 

Yonghong Song says:

====================
Commit 5a2798ab
("bpf: Add BTF_ID_LIST/BTF_ID/BTF_ID_UNUSED macros")
implemented a mechanism to compute btf_ids at kernel build
time which can simplify kernel implementation and reduce
runtime overhead by removing in-kernel btf_id calculation.

This patch set tried to use this mechanism to compute
btf_ids for bpf_skc_to_*() helpers and for btf_id_or_null ctx
arguments specified during bpf iterator registration.
Please see individual patch for details.

Changelogs:
  v1 -> v2:
    - v1 ([1]) is only for bpf_skc_to_*() helpers. This version
      expanded it to cover ctx btf_id_or_null arguments
    - abandoned the change of "extern u32 name[]" to
      "static u32 name[]" for BPF_ID_LIST local "name" definition.
      gcc 9 incurred a compilation error.

 [1]: https://lore.kernel.org/bpf/20200717184706.3476992-1-yhs@fb.com/T


====================

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parents e4d9c232 951cf368

include/linux/bpf.h

+1 −4
Original line number Diff line number Diff line
@@ -668,6 +668,7 @@ struct bpf_jit_poke_descriptor { 
struct bpf_ctx_arg_aux {

	u32 offset;

	enum bpf_reg_type reg_type;

	u32 btf_id;

};



struct bpf_prog_aux {
@@ -1541,7 +1542,6 @@ static inline bool bpf_map_is_dev_bound(struct bpf_map *map) 


struct bpf_map *bpf_map_offload_map_alloc(union bpf_attr *attr);

void bpf_map_offload_map_free(struct bpf_map *map);

void init_btf_sock_ids(struct btf *btf);

#else

static inline int bpf_prog_offload_init(struct bpf_prog *prog,

					union bpf_attr *attr)
@@ -1567,9 +1567,6 @@ static inline struct bpf_map *bpf_map_offload_map_alloc(union bpf_attr *attr) 
static inline void bpf_map_offload_map_free(struct bpf_map *map)

{

}

static inline void init_btf_sock_ids(struct btf *btf)

{

}

#endif /* CONFIG_NET && CONFIG_BPF_SYSCALL */



#if defined(CONFIG_BPF_STREAM_PARSER)

include/linux/btf_ids.h

+37 −3
Original line number Diff line number Diff line
@@ -57,17 +57,20 @@ asm( \ 
 * .zero 4

 *

 */

#define __BTF_ID_LIST(name)				\

#define __BTF_ID_LIST(name, scope)			\

asm(							\

".pushsection " BTF_IDS_SECTION ",\"a\";       \n"	\

".local " #name ";                             \n"	\

"." #scope " " #name ";                        \n"	\

#name ":;                                      \n"	\

".popsection;                                  \n");	\



#define BTF_ID_LIST(name)				\

__BTF_ID_LIST(name)					\

__BTF_ID_LIST(name, local)				\

extern u32 name[];



#define BTF_ID_LIST_GLOBAL(name)			\

__BTF_ID_LIST(name, globl)



/*

 * The BTF_ID_UNUSED macro defines 4 zero bytes.

 * It's used when we want to define 'unused' entry
@@ -90,7 +93,38 @@ asm( \ 
#define BTF_ID_LIST(name) static u32 name[5];

#define BTF_ID(prefix, name)

#define BTF_ID_UNUSED

#define BTF_ID_LIST_GLOBAL(name) u32 name[1];



#endif /* CONFIG_DEBUG_INFO_BTF */



#ifdef CONFIG_NET

/* Define a list of socket types which can be the argument for

 * skc_to_*_sock() helpers. All these sockets should have

 * sock_common as the first argument in its memory layout.

 */

#define BTF_SOCK_TYPE_xxx \

	BTF_SOCK_TYPE(BTF_SOCK_TYPE_INET, inet_sock)			\

	BTF_SOCK_TYPE(BTF_SOCK_TYPE_INET_CONN, inet_connection_sock)	\

	BTF_SOCK_TYPE(BTF_SOCK_TYPE_INET_REQ, inet_request_sock)	\

	BTF_SOCK_TYPE(BTF_SOCK_TYPE_INET_TW, inet_timewait_sock)	\

	BTF_SOCK_TYPE(BTF_SOCK_TYPE_REQ, request_sock)			\

	BTF_SOCK_TYPE(BTF_SOCK_TYPE_SOCK, sock)				\

	BTF_SOCK_TYPE(BTF_SOCK_TYPE_SOCK_COMMON, sock_common)		\

	BTF_SOCK_TYPE(BTF_SOCK_TYPE_TCP, tcp_sock)			\

	BTF_SOCK_TYPE(BTF_SOCK_TYPE_TCP_REQ, tcp_request_sock)		\

	BTF_SOCK_TYPE(BTF_SOCK_TYPE_TCP_TW, tcp_timewait_sock)		\

	BTF_SOCK_TYPE(BTF_SOCK_TYPE_TCP6, tcp6_sock)			\

	BTF_SOCK_TYPE(BTF_SOCK_TYPE_UDP, udp_sock)			\

	BTF_SOCK_TYPE(BTF_SOCK_TYPE_UDP6, udp6_sock)



enum {

#define BTF_SOCK_TYPE(name, str) name,

BTF_SOCK_TYPE_xxx

#undef BTF_SOCK_TYPE

MAX_BTF_SOCK_TYPE,

};



extern u32 btf_sock_ids[];

#endif



#endif

kernel/bpf/btf.c

+3 −3
Original line number Diff line number Diff line
@@ -3672,7 +3672,6 @@ struct btf *btf_parse_vmlinux(void) 
		goto errout;



	bpf_struct_ops_init(btf, log);

	init_btf_sock_ids(btf);



	btf_verifier_env_free(env);

	refcount_set(&btf->refcnt, 1);
@@ -3818,16 +3817,17 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type, 
		return true;



	/* this is a pointer to another type */

	info->reg_type = PTR_TO_BTF_ID;

	for (i = 0; i < prog->aux->ctx_arg_info_size; i++) {

		const struct bpf_ctx_arg_aux *ctx_arg_info = &prog->aux->ctx_arg_info[i];



		if (ctx_arg_info->offset == off) {

			info->reg_type = ctx_arg_info->reg_type;

			break;

			info->btf_id = ctx_arg_info->btf_id;

			return true;

		}

	}



	info->reg_type = PTR_TO_BTF_ID;

	if (tgt_prog) {

		ret = btf_translate_to_vmlinux(log, btf, t, tgt_prog->type, arg);

		if (ret > 0) {

kernel/bpf/map_iter.c

+6 −1
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ 
#include <linux/fs.h>

#include <linux/filter.h>

#include <linux/kernel.h>

#include <linux/btf_ids.h>



struct bpf_iter_seq_map_info {

	u32 mid;
@@ -81,7 +82,10 @@ static const struct seq_operations bpf_map_seq_ops = { 
	.show	= bpf_map_seq_show,

};



static const struct bpf_iter_reg bpf_map_reg_info = {

BTF_ID_LIST(btf_bpf_map_id)

BTF_ID(struct, bpf_map)



static struct bpf_iter_reg bpf_map_reg_info = {

	.target			= "bpf_map",

	.seq_ops		= &bpf_map_seq_ops,

	.init_seq_private	= NULL,
@@ -96,6 +100,7 @@ static const struct bpf_iter_reg bpf_map_reg_info = { 


static int __init bpf_map_iter_init(void)

{

	bpf_map_reg_info.ctx_arg_info[0].btf_id = *btf_bpf_map_id;

	return bpf_iter_reg_target(&bpf_map_reg_info);

}

kernel/bpf/task_iter.c

+10 −2
Original line number Diff line number Diff line
@@ -7,6 +7,7 @@ 
#include <linux/fs.h>

#include <linux/fdtable.h>

#include <linux/filter.h>

#include <linux/btf_ids.h>



struct bpf_iter_seq_task_common {

	struct pid_namespace *ns;
@@ -312,7 +313,11 @@ static const struct seq_operations task_file_seq_ops = { 
	.show	= task_file_seq_show,

};



static const struct bpf_iter_reg task_reg_info = {

BTF_ID_LIST(btf_task_file_ids)

BTF_ID(struct, task_struct)

BTF_ID(struct, file)



static struct bpf_iter_reg task_reg_info = {

	.target			= "task",

	.seq_ops		= &task_seq_ops,

	.init_seq_private	= init_seq_pidns,
@@ -325,7 +330,7 @@ static const struct bpf_iter_reg task_reg_info = { 
	},

};



static const struct bpf_iter_reg task_file_reg_info = {

static struct bpf_iter_reg task_file_reg_info = {

	.target			= "task_file",

	.seq_ops		= &task_file_seq_ops,

	.init_seq_private	= init_seq_pidns,
@@ -344,10 +349,13 @@ static int __init task_iter_init(void) 
{

	int ret;



	task_reg_info.ctx_arg_info[0].btf_id = btf_task_file_ids[0];

	ret = bpf_iter_reg_target(&task_reg_info);

	if (ret)

		return ret;



	task_file_reg_info.ctx_arg_info[0].btf_id = btf_task_file_ids[0];

	task_file_reg_info.ctx_arg_info[1].btf_id = btf_task_file_ids[1];

	return bpf_iter_reg_target(&task_file_reg_info);

}

late_initcall(task_iter_init);

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