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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: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210721000822.40958-4-alexei.starovoitov@gmail.com
This commit is contained in:
Alexei Starovoitov 2021-07-20 17:08:21 -07:00 committed by Andrii Nakryiko
parent 3ee4f53355
commit 301ba4d710
3 changed files with 102 additions and 93 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
tools/lib/bpf/libbpf.c
View File

@ -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 @@ err_out:
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;

71
tools/lib/bpf/libbpf_internal.h
View File

@ -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);

92
tools/lib/bpf/relo_core.h Normal file
View File

@ -0,0 +1,92 @@
/* 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