Commit 301ba4d7 authored by Alexei Starovoitov's avatar Alexei Starovoitov Committed by Andrii Nakryiko
Browse files

libbpf: Move CO-RE types into relo_core.h. 



In order to make a clean split of CO-RE logic move its types
into independent header file.

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210721000822.40958-4-alexei.starovoitov@gmail.com
parent 3ee4f533

tools/lib/bpf/libbpf.c

+9 −23
Original line number Diff line number Diff line
@@ -5022,34 +5022,20 @@ static size_t bpf_core_essential_name_len(const char *name) 
	return n;

}



struct core_cand

{

	const struct btf *btf;

	const struct btf_type *t;

	const char *name;

	__u32 id;

};



/* dynamically sized list of type IDs and its associated struct btf */

struct core_cand_list {

	struct core_cand *cands;

	int len;

};



static void bpf_core_free_cands(struct core_cand_list *cands)

static void bpf_core_free_cands(struct bpf_core_cand_list *cands)

{

	free(cands->cands);

	free(cands);

}



static int bpf_core_add_cands(struct core_cand *local_cand,

static int bpf_core_add_cands(struct bpf_core_cand *local_cand,

			      size_t local_essent_len,

			      const struct btf *targ_btf,

			      const char *targ_btf_name,

			      int targ_start_id,

			      struct core_cand_list *cands)

			      struct bpf_core_cand_list *cands)

{

	struct core_cand *new_cands, *cand;

	struct bpf_core_cand *new_cands, *cand;

	const struct btf_type *t;

	const char *targ_name;

	size_t targ_essent_len;
@@ -5185,11 +5171,11 @@ static int load_module_btfs(struct bpf_object *obj) 
	return 0;

}



static struct core_cand_list *

static struct bpf_core_cand_list *

bpf_core_find_cands(struct bpf_object *obj, const struct btf *local_btf, __u32 local_type_id)

{

	struct core_cand local_cand = {};

	struct core_cand_list *cands;

	struct bpf_core_cand local_cand = {};

	struct bpf_core_cand_list *cands;

	const struct btf *main_btf;

	size_t local_essent_len;

	int err, i;
@@ -6218,7 +6204,7 @@ static int bpf_core_apply_relo_insn(const char *prog_name, struct bpf_insn *insn 
				    const struct bpf_core_relo *relo,

				    int relo_idx,

				    const struct btf *local_btf,

				    struct core_cand_list *cands)

				    struct bpf_core_cand_list *cands)

{

	struct bpf_core_spec local_spec, cand_spec, targ_spec = {};

	struct bpf_core_relo_res cand_res, targ_res;
@@ -6372,7 +6358,7 @@ static int bpf_core_apply_relo(struct bpf_program *prog, 
			       struct hashmap *cand_cache)

{

	const void *type_key = u32_as_hash_key(relo->type_id);

	struct core_cand_list *cands = NULL;

	struct bpf_core_cand_list *cands = NULL;

	const char *prog_name = prog->name;

	const struct btf_type *local_type;

	const char *local_name;

tools/lib/bpf/libbpf_internal.h

+1 −70
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <errno.h>

#include <linux/err.h>

#include "libbpf_legacy.h"

#include "relo_core.h"



/* make sure libbpf doesn't use kernel-only integer typedefs */

#pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
@@ -366,76 +367,6 @@ struct bpf_line_info_min { 
	__u32	line_col;

};



/* bpf_core_relo_kind encodes which aspect of captured field/type/enum value

 * has to be adjusted by relocations.

 */

enum bpf_core_relo_kind {

	BPF_FIELD_BYTE_OFFSET = 0,	/* field byte offset */

	BPF_FIELD_BYTE_SIZE = 1,	/* field size in bytes */

	BPF_FIELD_EXISTS = 2,		/* field existence in target kernel */

	BPF_FIELD_SIGNED = 3,		/* field signedness (0 - unsigned, 1 - signed) */

	BPF_FIELD_LSHIFT_U64 = 4,	/* bitfield-specific left bitshift */

	BPF_FIELD_RSHIFT_U64 = 5,	/* bitfield-specific right bitshift */

	BPF_TYPE_ID_LOCAL = 6,		/* type ID in local BPF object */

	BPF_TYPE_ID_TARGET = 7,		/* type ID in target kernel */

	BPF_TYPE_EXISTS = 8,		/* type existence in target kernel */

	BPF_TYPE_SIZE = 9,		/* type size in bytes */

	BPF_ENUMVAL_EXISTS = 10,	/* enum value existence in target kernel */

	BPF_ENUMVAL_VALUE = 11,		/* enum value integer value */

};



/* The minimum bpf_core_relo checked by the loader

 *

 * CO-RE relocation captures the following data:

 * - insn_off - instruction offset (in bytes) within a BPF program that needs

 *   its insn->imm field to be relocated with actual field info;

 * - type_id - BTF type ID of the "root" (containing) entity of a relocatable

 *   type or field;

 * - access_str_off - offset into corresponding .BTF string section. String

 *   interpretation depends on specific relocation kind:

 *     - for field-based relocations, string encodes an accessed field using

 *     a sequence of field and array indices, separated by colon (:). It's

 *     conceptually very close to LLVM's getelementptr ([0]) instruction's

 *     arguments for identifying offset to a field.

 *     - for type-based relocations, strings is expected to be just "0";

 *     - for enum value-based relocations, string contains an index of enum

 *     value within its enum type;

 *

 * Example to provide a better feel.

 *

 *   struct sample {

 *       int a;

 *       struct {

 *           int b[10];

 *       };

 *   };

 *

 *   struct sample *s = ...;

 *   int x = &s->a;     // encoded as "0:0" (a is field #0)

 *   int y = &s->b[5];  // encoded as "0:1:0:5" (anon struct is field #1, 

 *                      // b is field #0 inside anon struct, accessing elem #5)

 *   int z = &s[10]->b; // encoded as "10:1" (ptr is used as an array)

 *

 * type_id for all relocs in this example  will capture BTF type id of

 * `struct sample`.

 *

 * Such relocation is emitted when using __builtin_preserve_access_index()

 * Clang built-in, passing expression that captures field address, e.g.:

 *

 * bpf_probe_read(&dst, sizeof(dst),

 *		  __builtin_preserve_access_index(&src->a.b.c));

 *

 * In this case Clang will emit field relocation recording necessary data to

 * be able to find offset of embedded `a.b.c` field within `src` struct.

 *

 *   [0] https://llvm.org/docs/LangRef.html#getelementptr-instruction

 */

struct bpf_core_relo {

	__u32   insn_off;

	__u32   type_id;

	__u32   access_str_off;

	enum bpf_core_relo_kind kind;

};



typedef int (*type_id_visit_fn)(__u32 *type_id, void *ctx);

typedef int (*str_off_visit_fn)(__u32 *str_off, void *ctx);

tools/lib/bpf/relo_core.h

0 → 100644
+92 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */

/* Copyright (c) 2019 Facebook */



#ifndef __RELO_CORE_H

#define __RELO_CORE_H



/* bpf_core_relo_kind encodes which aspect of captured field/type/enum value

 * has to be adjusted by relocations.

 */

enum bpf_core_relo_kind {

	BPF_FIELD_BYTE_OFFSET = 0,	/* field byte offset */

	BPF_FIELD_BYTE_SIZE = 1,	/* field size in bytes */

	BPF_FIELD_EXISTS = 2,		/* field existence in target kernel */

	BPF_FIELD_SIGNED = 3,		/* field signedness (0 - unsigned, 1 - signed) */

	BPF_FIELD_LSHIFT_U64 = 4,	/* bitfield-specific left bitshift */

	BPF_FIELD_RSHIFT_U64 = 5,	/* bitfield-specific right bitshift */

	BPF_TYPE_ID_LOCAL = 6,		/* type ID in local BPF object */

	BPF_TYPE_ID_TARGET = 7,		/* type ID in target kernel */

	BPF_TYPE_EXISTS = 8,		/* type existence in target kernel */

	BPF_TYPE_SIZE = 9,		/* type size in bytes */

	BPF_ENUMVAL_EXISTS = 10,	/* enum value existence in target kernel */

	BPF_ENUMVAL_VALUE = 11,		/* enum value integer value */

};



/* The minimum bpf_core_relo checked by the loader

 *

 * CO-RE relocation captures the following data:

 * - insn_off - instruction offset (in bytes) within a BPF program that needs

 *   its insn->imm field to be relocated with actual field info;

 * - type_id - BTF type ID of the "root" (containing) entity of a relocatable

 *   type or field;

 * - access_str_off - offset into corresponding .BTF string section. String

 *   interpretation depends on specific relocation kind:

 *     - for field-based relocations, string encodes an accessed field using

 *     a sequence of field and array indices, separated by colon (:). It's

 *     conceptually very close to LLVM's getelementptr ([0]) instruction's

 *     arguments for identifying offset to a field.

 *     - for type-based relocations, strings is expected to be just "0";

 *     - for enum value-based relocations, string contains an index of enum

 *     value within its enum type;

 *

 * Example to provide a better feel.

 *

 *   struct sample {

 *       int a;

 *       struct {

 *           int b[10];

 *       };

 *   };

 *

 *   struct sample *s = ...;

 *   int x = &s->a;     // encoded as "0:0" (a is field #0)

 *   int y = &s->b[5];  // encoded as "0:1:0:5" (anon struct is field #1,

 *                      // b is field #0 inside anon struct, accessing elem #5)

 *   int z = &s[10]->b; // encoded as "10:1" (ptr is used as an array)

 *

 * type_id for all relocs in this example  will capture BTF type id of

 * `struct sample`.

 *

 * Such relocation is emitted when using __builtin_preserve_access_index()

 * Clang built-in, passing expression that captures field address, e.g.:

 *

 * bpf_probe_read(&dst, sizeof(dst),

 *		  __builtin_preserve_access_index(&src->a.b.c));

 *

 * In this case Clang will emit field relocation recording necessary data to

 * be able to find offset of embedded `a.b.c` field within `src` struct.

 *

 *   [0] https://llvm.org/docs/LangRef.html#getelementptr-instruction

 */

struct bpf_core_relo {

	__u32   insn_off;

	__u32   type_id;

	__u32   access_str_off;

	enum bpf_core_relo_kind kind;

};



struct bpf_core_cand

{

	const struct btf *btf;

	const struct btf_type *t;

	const char *name;

	__u32 id;

};



/* dynamically sized list of type IDs and its associated struct btf */

struct bpf_core_cand_list {

	struct bpf_core_cand *cands;

	int len;

};



#endif