mirror of https://gitee.com/openkylin/linux.git
264 lines
11 KiB
C
264 lines
11 KiB
C
/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
|
|
#ifndef __BPF_CORE_READ_H__
|
|
#define __BPF_CORE_READ_H__
|
|
|
|
/*
|
|
* enum bpf_field_info_kind is passed as a second argument into
|
|
* __builtin_preserve_field_info() built-in to get a specific aspect of
|
|
* a field, captured as a first argument. __builtin_preserve_field_info(field,
|
|
* info_kind) returns __u32 integer and produces BTF field relocation, which
|
|
* is understood and processed by libbpf during BPF object loading. See
|
|
* selftests/bpf for examples.
|
|
*/
|
|
enum bpf_field_info_kind {
|
|
BPF_FIELD_BYTE_OFFSET = 0, /* field byte offset */
|
|
BPF_FIELD_BYTE_SIZE = 1,
|
|
BPF_FIELD_EXISTS = 2, /* field existence in target kernel */
|
|
BPF_FIELD_SIGNED = 3,
|
|
BPF_FIELD_LSHIFT_U64 = 4,
|
|
BPF_FIELD_RSHIFT_U64 = 5,
|
|
};
|
|
|
|
#define __CORE_RELO(src, field, info) \
|
|
__builtin_preserve_field_info((src)->field, BPF_FIELD_##info)
|
|
|
|
#if __BYTE_ORDER == __LITTLE_ENDIAN
|
|
#define __CORE_BITFIELD_PROBE_READ(dst, src, fld) \
|
|
bpf_probe_read((void *)dst, \
|
|
__CORE_RELO(src, fld, BYTE_SIZE), \
|
|
(const void *)src + __CORE_RELO(src, fld, BYTE_OFFSET))
|
|
#else
|
|
/* semantics of LSHIFT_64 assumes loading values into low-ordered bytes, so
|
|
* for big-endian we need to adjust destination pointer accordingly, based on
|
|
* field byte size
|
|
*/
|
|
#define __CORE_BITFIELD_PROBE_READ(dst, src, fld) \
|
|
bpf_probe_read((void *)dst + (8 - __CORE_RELO(src, fld, BYTE_SIZE)), \
|
|
__CORE_RELO(src, fld, BYTE_SIZE), \
|
|
(const void *)src + __CORE_RELO(src, fld, BYTE_OFFSET))
|
|
#endif
|
|
|
|
/*
|
|
* Extract bitfield, identified by s->field, and return its value as u64.
|
|
* All this is done in relocatable manner, so bitfield changes such as
|
|
* signedness, bit size, offset changes, this will be handled automatically.
|
|
* This version of macro is using bpf_probe_read() to read underlying integer
|
|
* storage. Macro functions as an expression and its return type is
|
|
* bpf_probe_read()'s return value: 0, on success, <0 on error.
|
|
*/
|
|
#define BPF_CORE_READ_BITFIELD_PROBED(s, field) ({ \
|
|
unsigned long long val = 0; \
|
|
\
|
|
__CORE_BITFIELD_PROBE_READ(&val, s, field); \
|
|
val <<= __CORE_RELO(s, field, LSHIFT_U64); \
|
|
if (__CORE_RELO(s, field, SIGNED)) \
|
|
val = ((long long)val) >> __CORE_RELO(s, field, RSHIFT_U64); \
|
|
else \
|
|
val = val >> __CORE_RELO(s, field, RSHIFT_U64); \
|
|
val; \
|
|
})
|
|
|
|
/*
|
|
* Extract bitfield, identified by s->field, and return its value as u64.
|
|
* This version of macro is using direct memory reads and should be used from
|
|
* BPF program types that support such functionality (e.g., typed raw
|
|
* tracepoints).
|
|
*/
|
|
#define BPF_CORE_READ_BITFIELD(s, field) ({ \
|
|
const void *p = (const void *)s + __CORE_RELO(s, field, BYTE_OFFSET); \
|
|
unsigned long long val; \
|
|
\
|
|
switch (__CORE_RELO(s, field, BYTE_SIZE)) { \
|
|
case 1: val = *(const unsigned char *)p; \
|
|
case 2: val = *(const unsigned short *)p; \
|
|
case 4: val = *(const unsigned int *)p; \
|
|
case 8: val = *(const unsigned long long *)p; \
|
|
} \
|
|
val <<= __CORE_RELO(s, field, LSHIFT_U64); \
|
|
if (__CORE_RELO(s, field, SIGNED)) \
|
|
val = ((long long)val) >> __CORE_RELO(s, field, RSHIFT_U64); \
|
|
else \
|
|
val = val >> __CORE_RELO(s, field, RSHIFT_U64); \
|
|
val; \
|
|
})
|
|
|
|
/*
|
|
* Convenience macro to check that field actually exists in target kernel's.
|
|
* Returns:
|
|
* 1, if matching field is present in target kernel;
|
|
* 0, if no matching field found.
|
|
*/
|
|
#define bpf_core_field_exists(field) \
|
|
__builtin_preserve_field_info(field, BPF_FIELD_EXISTS)
|
|
|
|
/*
|
|
* Convenience macro to get byte size of a field. Works for integers,
|
|
* struct/unions, pointers, arrays, and enums.
|
|
*/
|
|
#define bpf_core_field_size(field) \
|
|
__builtin_preserve_field_info(field, BPF_FIELD_BYTE_SIZE)
|
|
|
|
/*
|
|
* bpf_core_read() abstracts away bpf_probe_read() call and captures offset
|
|
* relocation for source address using __builtin_preserve_access_index()
|
|
* built-in, provided by Clang.
|
|
*
|
|
* __builtin_preserve_access_index() takes as an argument an expression of
|
|
* taking an address of a field within struct/union. It makes compiler emit
|
|
* a relocation, which records BTF type ID describing root struct/union and an
|
|
* accessor string which describes exact embedded field that was used to take
|
|
* an address. See detailed description of this relocation format and
|
|
* semantics in comments to struct bpf_field_reloc in libbpf_internal.h.
|
|
*
|
|
* This relocation allows libbpf to adjust BPF instruction to use correct
|
|
* actual field offset, based on target kernel BTF type that matches original
|
|
* (local) BTF, used to record relocation.
|
|
*/
|
|
#define bpf_core_read(dst, sz, src) \
|
|
bpf_probe_read(dst, sz, \
|
|
(const void *)__builtin_preserve_access_index(src))
|
|
|
|
/*
|
|
* bpf_core_read_str() is a thin wrapper around bpf_probe_read_str()
|
|
* additionally emitting BPF CO-RE field relocation for specified source
|
|
* argument.
|
|
*/
|
|
#define bpf_core_read_str(dst, sz, src) \
|
|
bpf_probe_read_str(dst, sz, \
|
|
(const void *)__builtin_preserve_access_index(src))
|
|
|
|
#define ___concat(a, b) a ## b
|
|
#define ___apply(fn, n) ___concat(fn, n)
|
|
#define ___nth(_1, _2, _3, _4, _5, _6, _7, _8, _9, _10, __11, N, ...) N
|
|
|
|
/*
|
|
* return number of provided arguments; used for switch-based variadic macro
|
|
* definitions (see ___last, ___arrow, etc below)
|
|
*/
|
|
#define ___narg(...) ___nth(_, ##__VA_ARGS__, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
|
|
/*
|
|
* return 0 if no arguments are passed, N - otherwise; used for
|
|
* recursively-defined macros to specify termination (0) case, and generic
|
|
* (N) case (e.g., ___read_ptrs, ___core_read)
|
|
*/
|
|
#define ___empty(...) ___nth(_, ##__VA_ARGS__, N, N, N, N, N, N, N, N, N, N, 0)
|
|
|
|
#define ___last1(x) x
|
|
#define ___last2(a, x) x
|
|
#define ___last3(a, b, x) x
|
|
#define ___last4(a, b, c, x) x
|
|
#define ___last5(a, b, c, d, x) x
|
|
#define ___last6(a, b, c, d, e, x) x
|
|
#define ___last7(a, b, c, d, e, f, x) x
|
|
#define ___last8(a, b, c, d, e, f, g, x) x
|
|
#define ___last9(a, b, c, d, e, f, g, h, x) x
|
|
#define ___last10(a, b, c, d, e, f, g, h, i, x) x
|
|
#define ___last(...) ___apply(___last, ___narg(__VA_ARGS__))(__VA_ARGS__)
|
|
|
|
#define ___nolast2(a, _) a
|
|
#define ___nolast3(a, b, _) a, b
|
|
#define ___nolast4(a, b, c, _) a, b, c
|
|
#define ___nolast5(a, b, c, d, _) a, b, c, d
|
|
#define ___nolast6(a, b, c, d, e, _) a, b, c, d, e
|
|
#define ___nolast7(a, b, c, d, e, f, _) a, b, c, d, e, f
|
|
#define ___nolast8(a, b, c, d, e, f, g, _) a, b, c, d, e, f, g
|
|
#define ___nolast9(a, b, c, d, e, f, g, h, _) a, b, c, d, e, f, g, h
|
|
#define ___nolast10(a, b, c, d, e, f, g, h, i, _) a, b, c, d, e, f, g, h, i
|
|
#define ___nolast(...) ___apply(___nolast, ___narg(__VA_ARGS__))(__VA_ARGS__)
|
|
|
|
#define ___arrow1(a) a
|
|
#define ___arrow2(a, b) a->b
|
|
#define ___arrow3(a, b, c) a->b->c
|
|
#define ___arrow4(a, b, c, d) a->b->c->d
|
|
#define ___arrow5(a, b, c, d, e) a->b->c->d->e
|
|
#define ___arrow6(a, b, c, d, e, f) a->b->c->d->e->f
|
|
#define ___arrow7(a, b, c, d, e, f, g) a->b->c->d->e->f->g
|
|
#define ___arrow8(a, b, c, d, e, f, g, h) a->b->c->d->e->f->g->h
|
|
#define ___arrow9(a, b, c, d, e, f, g, h, i) a->b->c->d->e->f->g->h->i
|
|
#define ___arrow10(a, b, c, d, e, f, g, h, i, j) a->b->c->d->e->f->g->h->i->j
|
|
#define ___arrow(...) ___apply(___arrow, ___narg(__VA_ARGS__))(__VA_ARGS__)
|
|
|
|
#define ___type(...) typeof(___arrow(__VA_ARGS__))
|
|
|
|
#define ___read(read_fn, dst, src_type, src, accessor) \
|
|
read_fn((void *)(dst), sizeof(*(dst)), &((src_type)(src))->accessor)
|
|
|
|
/* "recursively" read a sequence of inner pointers using local __t var */
|
|
#define ___rd_first(src, a) ___read(bpf_core_read, &__t, ___type(src), src, a);
|
|
#define ___rd_last(...) \
|
|
___read(bpf_core_read, &__t, \
|
|
___type(___nolast(__VA_ARGS__)), __t, ___last(__VA_ARGS__));
|
|
#define ___rd_p1(...) const void *__t; ___rd_first(__VA_ARGS__)
|
|
#define ___rd_p2(...) ___rd_p1(___nolast(__VA_ARGS__)) ___rd_last(__VA_ARGS__)
|
|
#define ___rd_p3(...) ___rd_p2(___nolast(__VA_ARGS__)) ___rd_last(__VA_ARGS__)
|
|
#define ___rd_p4(...) ___rd_p3(___nolast(__VA_ARGS__)) ___rd_last(__VA_ARGS__)
|
|
#define ___rd_p5(...) ___rd_p4(___nolast(__VA_ARGS__)) ___rd_last(__VA_ARGS__)
|
|
#define ___rd_p6(...) ___rd_p5(___nolast(__VA_ARGS__)) ___rd_last(__VA_ARGS__)
|
|
#define ___rd_p7(...) ___rd_p6(___nolast(__VA_ARGS__)) ___rd_last(__VA_ARGS__)
|
|
#define ___rd_p8(...) ___rd_p7(___nolast(__VA_ARGS__)) ___rd_last(__VA_ARGS__)
|
|
#define ___rd_p9(...) ___rd_p8(___nolast(__VA_ARGS__)) ___rd_last(__VA_ARGS__)
|
|
#define ___read_ptrs(src, ...) \
|
|
___apply(___rd_p, ___narg(__VA_ARGS__))(src, __VA_ARGS__)
|
|
|
|
#define ___core_read0(fn, dst, src, a) \
|
|
___read(fn, dst, ___type(src), src, a);
|
|
#define ___core_readN(fn, dst, src, ...) \
|
|
___read_ptrs(src, ___nolast(__VA_ARGS__)) \
|
|
___read(fn, dst, ___type(src, ___nolast(__VA_ARGS__)), __t, \
|
|
___last(__VA_ARGS__));
|
|
#define ___core_read(fn, dst, src, a, ...) \
|
|
___apply(___core_read, ___empty(__VA_ARGS__))(fn, dst, \
|
|
src, a, ##__VA_ARGS__)
|
|
|
|
/*
|
|
* BPF_CORE_READ_INTO() is a more performance-conscious variant of
|
|
* BPF_CORE_READ(), in which final field is read into user-provided storage.
|
|
* See BPF_CORE_READ() below for more details on general usage.
|
|
*/
|
|
#define BPF_CORE_READ_INTO(dst, src, a, ...) \
|
|
({ \
|
|
___core_read(bpf_core_read, dst, src, a, ##__VA_ARGS__) \
|
|
})
|
|
|
|
/*
|
|
* BPF_CORE_READ_STR_INTO() does same "pointer chasing" as
|
|
* BPF_CORE_READ() for intermediate pointers, but then executes (and returns
|
|
* corresponding error code) bpf_core_read_str() for final string read.
|
|
*/
|
|
#define BPF_CORE_READ_STR_INTO(dst, src, a, ...) \
|
|
({ \
|
|
___core_read(bpf_core_read_str, dst, src, a, ##__VA_ARGS__) \
|
|
})
|
|
|
|
/*
|
|
* BPF_CORE_READ() is used to simplify BPF CO-RE relocatable read, especially
|
|
* when there are few pointer chasing steps.
|
|
* E.g., what in non-BPF world (or in BPF w/ BCC) would be something like:
|
|
* int x = s->a.b.c->d.e->f->g;
|
|
* can be succinctly achieved using BPF_CORE_READ as:
|
|
* int x = BPF_CORE_READ(s, a.b.c, d.e, f, g);
|
|
*
|
|
* BPF_CORE_READ will decompose above statement into 4 bpf_core_read (BPF
|
|
* CO-RE relocatable bpf_probe_read() wrapper) calls, logically equivalent to:
|
|
* 1. const void *__t = s->a.b.c;
|
|
* 2. __t = __t->d.e;
|
|
* 3. __t = __t->f;
|
|
* 4. return __t->g;
|
|
*
|
|
* Equivalence is logical, because there is a heavy type casting/preservation
|
|
* involved, as well as all the reads are happening through bpf_probe_read()
|
|
* calls using __builtin_preserve_access_index() to emit CO-RE relocations.
|
|
*
|
|
* N.B. Only up to 9 "field accessors" are supported, which should be more
|
|
* than enough for any practical purpose.
|
|
*/
|
|
#define BPF_CORE_READ(src, a, ...) \
|
|
({ \
|
|
___type(src, a, ##__VA_ARGS__) __r; \
|
|
BPF_CORE_READ_INTO(&__r, src, a, ##__VA_ARGS__); \
|
|
__r; \
|
|
})
|
|
|
|
#endif
|
|
|