selftests/bpf: Add unit tests for bpf_arena_alloc/free_pages

Add unit tests for bpf_arena_alloc/free_pages() functionality
and bpf_arena_common.h with a set of common helpers and macros that
is used in this test and the following patches.

Also modify test_loader that didn't support running bpf_prog_type_syscall
programs.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240308010812.89848-13-alexei.starovoitov@gmail.com

1 files changed, 70 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/bpf_arena_common.h b/tools/testing/selftests/bpf/bpf_arena_common.h
new file mode 100644
index 000000000000..bcf195c64a45
--- /dev/null
+++ b/tools/testing/selftests/bpf/bpf_arena_common.h
@@ -0,0 +1,70 @@
+/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) */
+/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */
+#pragma once
+
+#ifndef WRITE_ONCE
+#define WRITE_ONCE(x, val) ((*(volatile typeof(x) *) &(x)) = (val))
+#endif
+
+#ifndef NUMA_NO_NODE
+#define	NUMA_NO_NODE	(-1)
+#endif
+
+#ifndef arena_container_of
+#define arena_container_of(ptr, type, member)			\
+	({							\
+		void __arena *__mptr = (void __arena *)(ptr);	\
+		((type *)(__mptr - offsetof(type, member)));	\
+	})
+#endif
+
+#ifdef __BPF__ /* when compiled as bpf program */
+
+#ifndef PAGE_SIZE
+#define PAGE_SIZE __PAGE_SIZE
+/*
+ * for older kernels try sizeof(struct genradix_node)
+ * or flexible:
+ * static inline long __bpf_page_size(void) {
+ *   return bpf_core_enum_value(enum page_size_enum___l, __PAGE_SIZE___l) ?: sizeof(struct genradix_node);
+ * }
+ * but generated code is not great.
+ */
+#endif
+
+#if defined(__BPF_FEATURE_ARENA_CAST) && !defined(BPF_ARENA_FORCE_ASM)
+#define __arena __attribute__((address_space(1)))
+#define cast_kern(ptr) /* nop for bpf prog. emitted by LLVM */
+#define cast_user(ptr) /* nop for bpf prog. emitted by LLVM */
+#else
+#define __arena
+#define cast_kern(ptr) bpf_addr_space_cast(ptr, 0, 1)
+#define cast_user(ptr) bpf_addr_space_cast(ptr, 1, 0)
+#endif
+
+void __arena* bpf_arena_alloc_pages(void *map, void __arena *addr, __u32 page_cnt,
+				    int node_id, __u64 flags) __ksym __weak;
+void bpf_arena_free_pages(void *map, void __arena *ptr, __u32 page_cnt) __ksym __weak;
+
+#else /* when compiled as user space code */
+
+#define __arena
+#define __arg_arena
+#define cast_kern(ptr) /* nop for user space */
+#define cast_user(ptr) /* nop for user space */
+__weak char arena[1];
+
+#ifndef offsetof
+#define offsetof(type, member)  ((unsigned long)&((type *)0)->member)
+#endif
+
+static inline void __arena* bpf_arena_alloc_pages(void *map, void *addr, __u32 page_cnt,
+						  int node_id, __u64 flags)
+{
+	return NULL;
+}
+static inline void bpf_arena_free_pages(void *map, void __arena *ptr, __u32 page_cnt)
+{
+}
+
+#endif