libbpf: move bpf_for(), bpf_for_each(), and bpf_repeat() into bpf_helpers.h
To make it easier for bleeding-edge BPF applications, such as sched_ext, to utilize open-coded iterators, move bpf_for(), bpf_for_each(), and bpf_repeat() macros from selftests/bpf-internal bpf_misc.h helper, to libbpf-provided bpf_helpers.h header. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20230418002148.3255690-6-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Andrii Nakryiko
Alexei Starovoitov
parent
30bbfe3236
commit
c5e6474167
|
|
@ -291,4 +291,107 @@ enum libbpf_tristate {
|
|||
/* Helper macro to print out debug messages */
|
||||
#define bpf_printk(fmt, args...) ___bpf_pick_printk(args)(fmt, ##args)
|
||||
|
||||
struct bpf_iter_num;
|
||||
|
||||
extern int bpf_iter_num_new(struct bpf_iter_num *it, int start, int end) __ksym;
|
||||
extern int *bpf_iter_num_next(struct bpf_iter_num *it) __ksym;
|
||||
extern void bpf_iter_num_destroy(struct bpf_iter_num *it) __ksym;
|
||||
|
||||
#ifndef bpf_for_each
|
||||
/* bpf_for_each(iter_type, cur_elem, args...) provides generic construct for
|
||||
* using BPF open-coded iterators without having to write mundane explicit
|
||||
* low-level loop logic. Instead, it provides for()-like generic construct
|
||||
* that can be used pretty naturally. E.g., for some hypothetical cgroup
|
||||
* iterator, you'd write:
|
||||
*
|
||||
* struct cgroup *cg, *parent_cg = <...>;
|
||||
*
|
||||
* bpf_for_each(cgroup, cg, parent_cg, CG_ITER_CHILDREN) {
|
||||
* bpf_printk("Child cgroup id = %d", cg->cgroup_id);
|
||||
* if (cg->cgroup_id == 123)
|
||||
* break;
|
||||
* }
|
||||
*
|
||||
* I.e., it looks almost like high-level for each loop in other languages,
|
||||
* supports continue/break, and is verifiable by BPF verifier.
|
||||
*
|
||||
* For iterating integers, the difference betwen bpf_for_each(num, i, N, M)
|
||||
* and bpf_for(i, N, M) is in that bpf_for() provides additional proof to
|
||||
* verifier that i is in [N, M) range, and in bpf_for_each() case i is `int
|
||||
* *`, not just `int`. So for integers bpf_for() is more convenient.
|
||||
*
|
||||
* Note: this macro relies on C99 feature of allowing to declare variables
|
||||
* inside for() loop, bound to for() loop lifetime. It also utilizes GCC
|
||||
* extension: __attribute__((cleanup(<func>))), supported by both GCC and
|
||||
* Clang.
|
||||
*/
|
||||
#define bpf_for_each(type, cur, args...) for ( \
|
||||
/* initialize and define destructor */ \
|
||||
struct bpf_iter_##type ___it __attribute__((aligned(8), /* enforce, just in case */, \
|
||||
cleanup(bpf_iter_##type##_destroy))), \
|
||||
/* ___p pointer is just to call bpf_iter_##type##_new() *once* to init ___it */ \
|
||||
*___p __attribute__((unused)) = ( \
|
||||
bpf_iter_##type##_new(&___it, ##args), \
|
||||
/* this is a workaround for Clang bug: it currently doesn't emit BTF */ \
|
||||
/* for bpf_iter_##type##_destroy() when used from cleanup() attribute */ \
|
||||
(void)bpf_iter_##type##_destroy, (void *)0); \
|
||||
/* iteration and termination check */ \
|
||||
(((cur) = bpf_iter_##type##_next(&___it))); \
|
||||
)
|
||||
#endif /* bpf_for_each */
|
||||
|
||||
#ifndef bpf_for
|
||||
/* bpf_for(i, start, end) implements a for()-like looping construct that sets
|
||||
* provided integer variable *i* to values starting from *start* through,
|
||||
* but not including, *end*. It also proves to BPF verifier that *i* belongs
|
||||
* to range [start, end), so this can be used for accessing arrays without
|
||||
* extra checks.
|
||||
*
|
||||
* Note: *start* and *end* are assumed to be expressions with no side effects
|
||||
* and whose values do not change throughout bpf_for() loop execution. They do
|
||||
* not have to be statically known or constant, though.
|
||||
*
|
||||
* Note: similarly to bpf_for_each(), it relies on C99 feature of declaring for()
|
||||
* loop bound variables and cleanup attribute, supported by GCC and Clang.
|
||||
*/
|
||||
#define bpf_for(i, start, end) for ( \
|
||||
/* initialize and define destructor */ \
|
||||
struct bpf_iter_num ___it __attribute__((aligned(8), /* enforce, just in case */ \
|
||||
cleanup(bpf_iter_num_destroy))), \
|
||||
/* ___p pointer is necessary to call bpf_iter_num_new() *once* to init ___it */ \
|
||||
*___p __attribute__((unused)) = ( \
|
||||
bpf_iter_num_new(&___it, (start), (end)), \
|
||||
/* this is a workaround for Clang bug: it currently doesn't emit BTF */ \
|
||||
/* for bpf_iter_num_destroy() when used from cleanup() attribute */ \
|
||||
(void)bpf_iter_num_destroy, (void *)0); \
|
||||
({ \
|
||||
/* iteration step */ \
|
||||
int *___t = bpf_iter_num_next(&___it); \
|
||||
/* termination and bounds check */ \
|
||||
(___t && ((i) = *___t, (i) >= (start) && (i) < (end))); \
|
||||
}); \
|
||||
)
|
||||
#endif /* bpf_for */
|
||||
|
||||
#ifndef bpf_repeat
|
||||
/* bpf_repeat(N) performs N iterations without exposing iteration number
|
||||
*
|
||||
* Note: similarly to bpf_for_each(), it relies on C99 feature of declaring for()
|
||||
* loop bound variables and cleanup attribute, supported by GCC and Clang.
|
||||
*/
|
||||
#define bpf_repeat(N) for ( \
|
||||
/* initialize and define destructor */ \
|
||||
struct bpf_iter_num ___it __attribute__((aligned(8), /* enforce, just in case */ \
|
||||
cleanup(bpf_iter_num_destroy))), \
|
||||
/* ___p pointer is necessary to call bpf_iter_num_new() *once* to init ___it */ \
|
||||
*___p __attribute__((unused)) = ( \
|
||||
bpf_iter_num_new(&___it, 0, (N)), \
|
||||
/* this is a workaround for Clang bug: it currently doesn't emit BTF */ \
|
||||
/* for bpf_iter_num_destroy() when used from cleanup() attribute */ \
|
||||
(void)bpf_iter_num_destroy, (void *)0); \
|
||||
bpf_iter_num_next(&___it); \
|
||||
/* nothing here */ \
|
||||
)
|
||||
#endif /* bpf_repeat */
|
||||
|
||||
#endif
|
||||
|
|
|
|||
|
|
@ -121,107 +121,4 @@
|
|||
/* make it look to compiler like value is read and written */
|
||||
#define __sink(expr) asm volatile("" : "+g"(expr))
|
||||
|
||||
struct bpf_iter_num;
|
||||
|
||||
extern int bpf_iter_num_new(struct bpf_iter_num *it, int start, int end) __ksym;
|
||||
extern int *bpf_iter_num_next(struct bpf_iter_num *it) __ksym;
|
||||
extern void bpf_iter_num_destroy(struct bpf_iter_num *it) __ksym;
|
||||
|
||||
#ifndef bpf_for_each
|
||||
/* bpf_for_each(iter_type, cur_elem, args...) provides generic construct for
|
||||
* using BPF open-coded iterators without having to write mundane explicit
|
||||
* low-level loop logic. Instead, it provides for()-like generic construct
|
||||
* that can be used pretty naturally. E.g., for some hypothetical cgroup
|
||||
* iterator, you'd write:
|
||||
*
|
||||
* struct cgroup *cg, *parent_cg = <...>;
|
||||
*
|
||||
* bpf_for_each(cgroup, cg, parent_cg, CG_ITER_CHILDREN) {
|
||||
* bpf_printk("Child cgroup id = %d", cg->cgroup_id);
|
||||
* if (cg->cgroup_id == 123)
|
||||
* break;
|
||||
* }
|
||||
*
|
||||
* I.e., it looks almost like high-level for each loop in other languages,
|
||||
* supports continue/break, and is verifiable by BPF verifier.
|
||||
*
|
||||
* For iterating integers, the difference betwen bpf_for_each(num, i, N, M)
|
||||
* and bpf_for(i, N, M) is in that bpf_for() provides additional proof to
|
||||
* verifier that i is in [N, M) range, and in bpf_for_each() case i is `int
|
||||
* *`, not just `int`. So for integers bpf_for() is more convenient.
|
||||
*
|
||||
* Note: this macro relies on C99 feature of allowing to declare variables
|
||||
* inside for() loop, bound to for() loop lifetime. It also utilizes GCC
|
||||
* extension: __attribute__((cleanup(<func>))), supported by both GCC and
|
||||
* Clang.
|
||||
*/
|
||||
#define bpf_for_each(type, cur, args...) for ( \
|
||||
/* initialize and define destructor */ \
|
||||
struct bpf_iter_##type ___it __attribute__((aligned(8), /* enforce, just in case */, \
|
||||
cleanup(bpf_iter_##type##_destroy))), \
|
||||
/* ___p pointer is just to call bpf_iter_##type##_new() *once* to init ___it */ \
|
||||
*___p __attribute__((unused)) = ( \
|
||||
bpf_iter_##type##_new(&___it, ##args), \
|
||||
/* this is a workaround for Clang bug: it currently doesn't emit BTF */ \
|
||||
/* for bpf_iter_##type##_destroy() when used from cleanup() attribute */ \
|
||||
(void)bpf_iter_##type##_destroy, (void *)0); \
|
||||
/* iteration and termination check */ \
|
||||
(((cur) = bpf_iter_##type##_next(&___it))); \
|
||||
)
|
||||
#endif /* bpf_for_each */
|
||||
|
||||
#ifndef bpf_for
|
||||
/* bpf_for(i, start, end) implements a for()-like looping construct that sets
|
||||
* provided integer variable *i* to values starting from *start* through,
|
||||
* but not including, *end*. It also proves to BPF verifier that *i* belongs
|
||||
* to range [start, end), so this can be used for accessing arrays without
|
||||
* extra checks.
|
||||
*
|
||||
* Note: *start* and *end* are assumed to be expressions with no side effects
|
||||
* and whose values do not change throughout bpf_for() loop execution. They do
|
||||
* not have to be statically known or constant, though.
|
||||
*
|
||||
* Note: similarly to bpf_for_each(), it relies on C99 feature of declaring for()
|
||||
* loop bound variables and cleanup attribute, supported by GCC and Clang.
|
||||
*/
|
||||
#define bpf_for(i, start, end) for ( \
|
||||
/* initialize and define destructor */ \
|
||||
struct bpf_iter_num ___it __attribute__((aligned(8), /* enforce, just in case */ \
|
||||
cleanup(bpf_iter_num_destroy))), \
|
||||
/* ___p pointer is necessary to call bpf_iter_num_new() *once* to init ___it */ \
|
||||
*___p __attribute__((unused)) = ( \
|
||||
bpf_iter_num_new(&___it, (start), (end)), \
|
||||
/* this is a workaround for Clang bug: it currently doesn't emit BTF */ \
|
||||
/* for bpf_iter_num_destroy() when used from cleanup() attribute */ \
|
||||
(void)bpf_iter_num_destroy, (void *)0); \
|
||||
({ \
|
||||
/* iteration step */ \
|
||||
int *___t = bpf_iter_num_next(&___it); \
|
||||
/* termination and bounds check */ \
|
||||
(___t && ((i) = *___t, (i) >= (start) && (i) < (end))); \
|
||||
}); \
|
||||
)
|
||||
#endif /* bpf_for */
|
||||
|
||||
#ifndef bpf_repeat
|
||||
/* bpf_repeat(N) performs N iterations without exposing iteration number
|
||||
*
|
||||
* Note: similarly to bpf_for_each(), it relies on C99 feature of declaring for()
|
||||
* loop bound variables and cleanup attribute, supported by GCC and Clang.
|
||||
*/
|
||||
#define bpf_repeat(N) for ( \
|
||||
/* initialize and define destructor */ \
|
||||
struct bpf_iter_num ___it __attribute__((aligned(8), /* enforce, just in case */ \
|
||||
cleanup(bpf_iter_num_destroy))), \
|
||||
/* ___p pointer is necessary to call bpf_iter_num_new() *once* to init ___it */ \
|
||||
*___p __attribute__((unused)) = ( \
|
||||
bpf_iter_num_new(&___it, 0, (N)), \
|
||||
/* this is a workaround for Clang bug: it currently doesn't emit BTF */ \
|
||||
/* for bpf_iter_num_destroy() when used from cleanup() attribute */ \
|
||||
(void)bpf_iter_num_destroy, (void *)0); \
|
||||
bpf_iter_num_next(&___it); \
|
||||
/* nothing here */ \
|
||||
)
|
||||
#endif /* bpf_repeat */
|
||||
|
||||
#endif
|
||||
|
|
|
|||
Loading…
Reference in New Issue