[PATCH bpf-next v4 7/8] selftests/bpf: cast explicitly in the struct_ops arena triggers

[Vineet Gupta <vineet.gupta@linux.dev>]

trigger() in struct_ops_arena.c and its three siblings puts the
__BPF_FEATURE_ADDR_SPACE_CAST guard inside the function, so without
arena support the body is gone and the program falls through to
"return 0". The host side then does

  err = bpf_prog_test_run_opts(bpf_program__fd(trigger), &topts);
  ASSERT_OK(err, "test_run");
  ASSERT_EQ(topts.retval, 0, "trigger_retval");

and passes, having run a program that did nothing.

These are not driven by test_loader, so __skip_without_arena cannot
reach them. They do not need it: cast_kern() is a nop when the
compiler supports the address space and bpf_addr_space_cast(ptr, 0, 1)
when it does not, so one cast makes the body work either way and the
tests run for real instead of being skipped.

No verdict changes: struct_ops_arena/arena_arg and /arena_autobind
reported OK before, from an empty body, and report OK now from one
that runs. What changes is that the OK means something.

Signed-off-by: Vineet Gupta <vineet.gupta@linux.dev>
---
v3 -> v4: was 8/8. cast_kern() instead of the skip_tests flag in
.data, so these run rather than skip. (Alexei)

 tools/testing/selftests/bpf/progs/struct_ops_arena.c           | 3 +--
 tools/testing/selftests/bpf/progs/struct_ops_arena_autobind.c  | 3 +--
 tools/testing/selftests/bpf/progs/struct_ops_arena_member.c    | 3 +--
 .../selftests/bpf/progs/struct_ops_arena_member_render.c       | 3 +--
 4 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/tools/testing/selftests/bpf/progs/struct_ops_arena.c b/tools/testing/selftests/bpf/progs/struct_ops_arena.c
index 8aa8639df91f..3fffa24839ee 100644
--- a/tools/testing/selftests/bpf/progs/struct_ops_arena.c
+++ b/tools/testing/selftests/bpf/progs/struct_ops_arena.c
@@ -86,7 +86,6 @@ struct bpf_testmod_ops3 testmod_arena = {
 SEC("syscall")
 int trigger(void *ctx)
 {
-#if defined(__BPF_FEATURE_ADDR_SPACE_CAST)
 	u64 __arena *val;
 	int ret;
 
@@ -94,6 +93,7 @@ int trigger(void *ctx)
 	if (!val)
 		return 1;
 
+	cast_kern(val);
 	*val = 41;
 	ret = bpf_testmod_ops3_call_test_arena((u64 *)val);
 	if (ret)
@@ -134,6 +134,5 @@ int trigger(void *ctx)
 		return 11;
 
 	bpf_arena_free_pages(&arena, (void __arena *)val, 1);
-#endif
 	return 0;
 }
diff --git a/tools/testing/selftests/bpf/progs/struct_ops_arena_autobind.c b/tools/testing/selftests/bpf/progs/struct_ops_arena_autobind.c
index 495faa0f4a8b..3455ca9e2d47 100644
--- a/tools/testing/selftests/bpf/progs/struct_ops_arena_autobind.c
+++ b/tools/testing/selftests/bpf/progs/struct_ops_arena_autobind.c
@@ -45,13 +45,13 @@ int unrelated(void *ctx)
 SEC("syscall")
 int trigger(void *ctx)
 {
-#if defined(__BPF_FEATURE_ADDR_SPACE_CAST)
 	u64 __arena *val;
 
 	val = bpf_arena_alloc_pages(&arena, NULL, 1, NUMA_NO_NODE, 0);
 	if (!val)
 		return 1;
 
+	cast_kern(val);
 	*val = 41;
 	if (bpf_testmod_ops3_call_test_arena((u64 *)val))
 		return 2;
@@ -59,6 +59,5 @@ int trigger(void *ctx)
 		return 3;
 
 	bpf_arena_free_pages(&arena, (void __arena *)val, 1);
-#endif
 	return 0;
 }
diff --git a/tools/testing/selftests/bpf/progs/struct_ops_arena_member.c b/tools/testing/selftests/bpf/progs/struct_ops_arena_member.c
index a2218cd81619..afbe59f77af6 100644
--- a/tools/testing/selftests/bpf/progs/struct_ops_arena_member.c
+++ b/tools/testing/selftests/bpf/progs/struct_ops_arena_member.c
@@ -80,7 +80,6 @@ struct bpf_testmod_ops3 testmod_arena_member = {
 SEC("syscall")
 int trigger(void *ctx)
 {
-#if defined(__BPF_FEATURE_ADDR_SPACE_CAST)
 	u64 __arena *val;
 	int ret;
 
@@ -88,6 +87,7 @@ int trigger(void *ctx)
 	if (!val)
 		return 1;
 
+	cast_kern(val);
 	*val = 41;
 	ret = bpf_testmod_ops3_call_test_arena_member((u64 *)val);
 	if (ret)
@@ -104,6 +104,5 @@ int trigger(void *ctx)
 		return 4;
 
 	bpf_arena_free_pages(&arena, (void __arena *)val, 1);
-#endif
 	return 0;
 }
diff --git a/tools/testing/selftests/bpf/progs/struct_ops_arena_member_render.c b/tools/testing/selftests/bpf/progs/struct_ops_arena_member_render.c
index 09b4c740bdca..c4e134e14f87 100644
--- a/tools/testing/selftests/bpf/progs/struct_ops_arena_member_render.c
+++ b/tools/testing/selftests/bpf/progs/struct_ops_arena_member_render.c
@@ -63,7 +63,6 @@ struct bpf_testmod_ops3 testmod_arena_member_render = {
 SEC("syscall")
 int trigger(void *ctx)
 {
-#if defined(__BPF_FEATURE_ADDR_SPACE_CAST)
 	u64 __arena *val;
 	int ret;
 
@@ -71,6 +70,7 @@ int trigger(void *ctx)
 	if (!val)
 		return 1;
 
+	cast_kern(val);
 	*val = 41;
 	ret = bpf_testmod_ops3_call_test_arena_member((u64 *)val);
 	if (ret)
@@ -80,6 +80,5 @@ int trigger(void *ctx)
 		return 3;
 
 	bpf_arena_free_pages(&arena, (void __arena *)val, 1);
-#endif
 	return 0;
 }
-- 
2.53.0-Meta