libbpf, selftests/bpf: Adjust libbpf, bpftool, selftests to match LLVM

The selftests use
to tell LLVM about special pointers. For LLVM there is nothing "arena"
about them. They are simply pointers in a different address space.
Hence LLVM diff https://github.com/llvm/llvm-project/pull/85161 renamed:
. macro __BPF_FEATURE_ARENA_CAST -> __BPF_FEATURE_ADDR_SPACE_CAST
. global variables in __attribute__((address_space(N))) are now
placed in section named ".addr_space.N" instead of ".arena.N".

Adjust libbpf, bpftool, and selftests to match LLVM.

Signed-off-by: Alexei Starovoitov <[e-mail]>
Signed-off-by: Andrii Nakryiko <[e-mail]>
Acked-by: Stanislav Fomichev <[e-mail]>
Link: https://lore.kernel.org/bpf/[e-mail]

tools/bpf/bpftool/gen.c

···
 	int i, n;
 
 	/* recognize hard coded LLVM section name */
-	if (strcmp(sec_name, ".arena.1") == 0) {
+	if (strcmp(sec_name, ".addr_space.1") == 0) {
 		/* this is the name to use in skeleton */
 		snprintf(buf, buf_sz, "arena");
 		return true;

tools/lib/bpf/libbpf.c

···
 #define KSYMS_SEC ".ksyms"
 #define STRUCT_OPS_SEC ".struct_ops"
 #define STRUCT_OPS_LINK_SEC ".struct_ops.link"
-#define ARENA_SEC ".arena.1"
+#define ARENA_SEC ".addr_space.1"
 
 enum libbpf_map_type {
 	LIBBPF_MAP_UNSPEC,

tools/testing/selftests/bpf/bpf_arena_common.h

···
  */
 #endif
 
-#if defined(__BPF_FEATURE_ARENA_CAST) && !defined(BPF_ARENA_FORCE_ASM)
+#if defined(__BPF_FEATURE_ADDR_SPACE_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 */

tools/testing/selftests/bpf/progs/arena_htab.c

···
 SEC("syscall")
 int arena_htab_llvm(void *ctx)
 {
-#if defined(__BPF_FEATURE_ARENA_CAST) || defined(BPF_ARENA_FORCE_ASM)
+#if defined(__BPF_FEATURE_ADDR_SPACE_CAST) || defined(BPF_ARENA_FORCE_ASM)
 	struct htab __arena *htab;
 	__u64 i;
 

tools/testing/selftests/bpf/progs/arena_list.c

···
 int cnt;
 bool skip = false;
 
-#ifdef __BPF_FEATURE_ARENA_CAST
+#ifdef __BPF_FEATURE_ADDR_SPACE_CAST
 long __arena arena_sum;
 int __arena test_val = 1;
 struct arena_list_head __arena global_head;
 #else
-long arena_sum SEC(".arena.1");
-int test_val SEC(".arena.1");
+long arena_sum SEC(".addr_space.1");
+int test_val SEC(".addr_space.1");
 #endif
 
 int zero;
···
 SEC("syscall")
 int arena_list_add(void *ctx)
 {
-#ifdef __BPF_FEATURE_ARENA_CAST
+#ifdef __BPF_FEATURE_ADDR_SPACE_CAST
 	__u64 i;
 
 	list_head = &global_head;
···
 SEC("syscall")
 int arena_list_del(void *ctx)
 {
-#ifdef __BPF_FEATURE_ARENA_CAST
+#ifdef __BPF_FEATURE_ADDR_SPACE_CAST
 	struct elem __arena *n;
 	int sum = 0;
 

tools/testing/selftests/bpf/progs/verifier_arena.c

···
 __success __retval(0)
 int basic_alloc1(void *ctx)
 {
-#if defined(__BPF_FEATURE_ARENA_CAST)
+#if defined(__BPF_FEATURE_ADDR_SPACE_CAST)
 	volatile int __arena *page1, *page2, *no_page, *page3;
 
 	page1 = bpf_arena_alloc_pages(&arena, NULL, 1, NUMA_NO_NODE, 0);
···
 __success __retval(0)
 int basic_alloc2(void *ctx)
 {
-#if defined(__BPF_FEATURE_ARENA_CAST)
+#if defined(__BPF_FEATURE_ADDR_SPACE_CAST)
 	volatile char __arena *page1, *page2, *page3, *page4;
 
 	page1 = bpf_arena_alloc_pages(&arena, NULL, 2, NUMA_NO_NODE, 0);