selftests/bpf: Factor out arena test from compute_live_registers

Prior commit [0] bundled multiple tests for compute_live_registers(), with
only one being arena-specific. Since kernel arena code is compiled-in only
if supported, this results in run-time failure of *all* otherwise portable
tests, e.g. on armhf 32-bit:

run_subtest:PASS:obj_open_mem 0 nsec
libbpf: map 'arena': failed to create: -EINVAL
run_subtest:FAIL:unexpected_load_failure unexpected error: -22 (errno 22)
torvalds#68/1    compute_live_registers/assign_chain:FAIL

Previous arena test code was mainly added as separate source files [1],
allowing either their temporary removal as a workaround or, ultimately,
exclusion via Makefile to build successfully. Follow the prior approach
by separating out arena-specific test source.

0: ("selftests/bpf: test cases for compute_live_registers()")
1: arena_spin_lock.c, arena_atomics.c, arena_htab.c, arena_htab_asm.c,
   arena_list.c, verifier_arena.c, verifier_arena_large.c

Signed-off-by: Tony Ambardar <[email protected]>

Author: guidosarducci

tools/testing/selftests/bpf/prog_tests/compute_live_registers_arena.c

@@ -0,0 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "compute_live_registers_arena.skel.h"
+#include "test_progs.h"
+
+void test_compute_live_registers_arena(void)
+{
+	RUN_TESTS(compute_live_registers_arena);
+}
+

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

@@ -3,7 +3,6 @@
 #include <linux/bpf.h>
 #include <bpf/bpf_helpers.h>
 #include "../../../include/linux/filter.h"
-#include "bpf_arena_common.h"
 #include "bpf_misc.h"
 
 struct {
@@ -13,12 +12,6 @@ struct {
 	__type(value, __u64);
 } test_map SEC(".maps");
 
-struct {
-	__uint(type, BPF_MAP_TYPE_ARENA);
-	__uint(map_flags, BPF_F_MMAPABLE);
-	__uint(max_entries, 1);
-} arena SEC(".maps");
-
 SEC("socket")
 __log_level(2)
 __msg(" 0: .......... (b7) r0 = 42")
@@ -370,33 +363,6 @@ __naked void ldabs(void)
 }
 
 
-#ifdef __BPF_FEATURE_ADDR_SPACE_CAST
-SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
-__log_level(2)
-__msg(" 6: .12345.... (85) call bpf_arena_alloc_pages")
-__msg(" 7: 0......... (bf) r1 = addr_space_cast(r0, 0, 1)")
-__msg(" 8: .1........ (b7) r2 = 42")
-__naked void addr_space_cast(void)
-{
-	asm volatile (
-		"r1 = %[arena] ll;"
-		"r2 = 0;"
-		"r3 = 1;"
-		"r4 = 0;"
-		"r5 = 0;"
-		"call %[bpf_arena_alloc_pages];"
-		"r1 = addr_space_cast(r0, 0, 1);"
-		"r2 = 42;"
-		"*(u64 *)(r1 +0) = r2;"
-		"r0 = 0;"
-		"exit;"
-		:
-		: __imm(bpf_arena_alloc_pages),
-		  __imm_addr(arena)
-		: __clobber_all);
-}
-#endif
-
 static __used __naked int aux1(void)
 {
 	asm volatile (
@@ -431,10 +397,4 @@ __naked void subprog1(void)
 		::: __clobber_all);
 }
 
-/* to retain debug info for BTF generation */
-void kfunc_root(void)
-{
-	bpf_arena_alloc_pages(0, 0, 0, 0, 0);
-}
-
 char _license[] SEC("license") = "GPL";

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

@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_arena_common.h"
+#include "bpf_misc.h"
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARENA);
+	__uint(map_flags, BPF_F_MMAPABLE);
+	__uint(max_entries, 1);
+} arena SEC(".maps");
+
+#ifdef __BPF_FEATURE_ADDR_SPACE_CAST
+SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
+__log_level(2)
+__msg(" 6: .12345.... (85) call bpf_arena_alloc_pages")
+__msg(" 7: 0......... (bf) r1 = addr_space_cast(r0, 0, 1)")
+__msg(" 8: .1........ (b7) r2 = 42")
+__naked void addr_space_cast(void)
+{
+	asm volatile (
+		"r1 = %[arena] ll;"
+		"r2 = 0;"
+		"r3 = 1;"
+		"r4 = 0;"
+		"r5 = 0;"
+		"call %[bpf_arena_alloc_pages];"
+		"r1 = addr_space_cast(r0, 0, 1);"
+		"r2 = 42;"
+		"*(u64 *)(r1 +0) = r2;"
+		"r0 = 0;"
+		"exit;"
+		:
+		: __imm(bpf_arena_alloc_pages),
+		  __imm_addr(arena)
+		: __clobber_all);
+}
+#endif
+
+/* to retain debug info for BTF generation */
+void kfunc_root(void)
+{
+	bpf_arena_alloc_pages(0, 0, 0, 0, 0);
+}
+
+char _license[] SEC("license") = "GPL";
+