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>

diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h
index e7e1a8a..525dec6 100644 (file)
--- a/tools/lib/bpf/bpf_helpers.h
+++ b/tools/lib/bpf/bpf_helpers.h
@@ -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

diff --git a/tools/testing/selftests/bpf/progs/bpf_misc.h b/tools/testing/selftests/bpf/progs/bpf_misc.h
index 6e3b490..3b307de 100644 (file)
--- a/tools/testing/selftests/bpf/progs/bpf_misc.h
+++ b/tools/testing/selftests/bpf/progs/bpf_misc.h
@@ -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