On 10/22/25 12:18 AM, Jiayuan Chen wrote:
When compiling the BPF selftests with Clang versions that do not support
the addr_space_cast builtin, the build fails with assembly errors in
"verifier_ldsx.c" [1].
The root cause is that the inline assembly using addr_space_cast is
being processed by a compiler that lacks this feature. To resolve this,
wrap the affected code sections (specifically the arena_ldsx_* test
functions) with #if defined(__BPF_FEATURE_ADDR_SPACE_CAST). This
ensures the code is only compiled when the Clang supports the necessary
feature, preventing build failures on older or incompatible compiler
versions.
This change maintains test coverage for systems with support while
allowing the tests to build successfully in all environments.
[1]:
root:tools/testing/selftests/bpf$ make
CLNG-BPF [test_progs] verifier_ldsx.bpf.o
progs/verifier_ldsx.c:322:2: error: invalid operand for instruction
322 | "r1 = %[arena] ll;"
| ^
<inline asm>:1:52: note: instantiated into assembly here
1 | r1 = arena ll;r0 = 0xdeadbeef;r0 = addr_space_cast(r0,...
| ^
I think you are using llvm18 and earlier. Why can you upgrade to llvm19 and
later
which should solve the problem?
Fixes: f61654912404 ("selftests: bpf: Add tests for signed loads from arena")
We do not need to have Fixes. compiler is also moving forward, we cannot support
really old compiler and it is no point to have __BPF_FEATURE_ADDR_SPACE_CAST
for really old compilers. So at some point, __BPF_FEATURE_ADDR_SPACE_CAST will
become default.
Signed-off-by: Jiayuan Chen <[email protected]>
---
tools/testing/selftests/bpf/progs/verifier_ldsx.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/tools/testing/selftests/bpf/progs/verifier_ldsx.c
b/tools/testing/selftests/bpf/progs/verifier_ldsx.c
index c8494b682c31..cefa02e417d3 100644
--- a/tools/testing/selftests/bpf/progs/verifier_ldsx.c
+++ b/tools/testing/selftests/bpf/progs/verifier_ldsx.c
@@ -263,6 +263,7 @@ __naked void ldsx_ctx_8(void)
: __clobber_all);
}
+#if defined(__BPF_FEATURE_ADDR_SPACE_CAST)
SEC("syscall")
__description("Arena LDSX Disasm")
__success
@@ -425,6 +426,7 @@ __naked void arena_ldsx_s32(void *ctx)
: __clobber_all
);
}
+#endif
If you are really using llvm18, then I found there are some other
build failures as well, e.g.,
/home/yhs/work/bpf-next/tools/testing/selftests/bpf/bpf_arena_common.h:47:15:
error: conflicting types for 'bpf_arena_alloc_pages'
47 | void __arena* bpf_arena_alloc_pages(void *map, void __arena *addr,
__u32 page_cnt,
| ^
/home/yhs/work/bpf-next/tools/testing/selftests/bpf/tools/include/vmlinux.h:160636:48:
note: previous declaration is here
160636 | extern void __attribute__((address_space(1)))
*bpf_arena_alloc_pages(void *p__map, void __attribute__((address_space(1)))
*addr__ign, u32 page_cnt, int node_id, u64 flags) __weak __ksym;
| ^
In file included from progs/stream.c:8:
/home/yhs/work/bpf-next/tools/testing/selftests/bpf/bpf_arena_common.h:49:5:
error: conflicting types for 'bpf_arena_reserve_pages'
49 | int bpf_arena_reserve_pages(void *map, void __arena *addr, __u32
page_cnt) __ksym __weak;
| ^
/home/yhs/work/bpf-next/tools/testing/selftests/bpf/tools/include/vmlinux.h:160638:12:
note: previous declaration is here
160638 | extern int bpf_arena_reserve_pages(void *p__map, void
__attribute__((address_space(1))) *ptr__ign, u32 page_cnt) __weak __ksym;
| ^
In file included from progs/stream.c:8:
/home/yhs/work/bpf-next/tools/testing/selftests/bpf/bpf_arena_common.h:50:6:
error: conflicting types for 'bpf_arena_free_pages'
50 | void bpf_arena_free_pages(void *map, void __arena *ptr, __u32 page_cnt)
__ksym __weak;
| ^
/home/yhs/work/bpf-next/tools/testing/selftests/bpf/tools/include/vmlinux.h:160637:13:
note: previous declaration is here
160637 | extern void bpf_arena_free_pages(void *p__map, void
__attribute__((address_space(1))) *ptr__ign, u32 page_cnt) __weak __ksym;
| ^
Please cover all build failures at once.
/* to retain debug info for BTF generation */
void kfunc_root(void)
