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| author | Anton Protopopov <a.s.protopopov@gmail.com> | 2025-05-02 19:30:31 +0000 |
|---|---|---|
| committer | Andrii Nakryiko <andrii@kernel.org> | 2025-05-05 14:20:28 -0700 |
| commit | 41d4ce6df3f4945341ec509a840cc002a413b6cc (patch) | |
| tree | 4d9fefb63d654a334b14c4360e8ca51dfa8fb304 | |
| parent | a28fe3160362f92b0a1ae4a711244c75b41f4955 (diff) | |
bpf: Fix uninitialized values in BPF_{CORE,PROBE}_READ
With the latest LLVM bpf selftests build will fail with
the following error message:
progs/profiler.inc.h:710:31: error: default initialization of an object of type 'typeof ((parent_task)->real_cred->uid.val)' (aka 'const unsigned int') leaves the object uninitialized and is incompatible with C++ [-Werror,-Wdefault-const-init-unsafe]
710 | proc_exec_data->parent_uid = BPF_CORE_READ(parent_task, real_cred, uid.val);
| ^
tools/testing/selftests/bpf/tools/include/bpf/bpf_core_read.h:520:35: note: expanded from macro 'BPF_CORE_READ'
520 | ___type((src), a, ##__VA_ARGS__) __r; \
| ^
This happens because BPF_CORE_READ (and other macro) declare the
variable __r using the ___type macro which can inherit const modifier
from intermediate types.
Fix this by using __typeof_unqual__, when supported. (And when it
is not supported, the problem shouldn't appear, as older compilers
haven't complained.)
Fixes: 792001f4f7aa ("libbpf: Add user-space variants of BPF_CORE_READ() family of macros")
Fixes: a4b09a9ef945 ("libbpf: Add non-CO-RE variants of BPF_CORE_READ() macro family")
Signed-off-by: Anton Protopopov <a.s.protopopov@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250502193031.3522715-1-a.s.protopopov@gmail.com
| -rw-r--r-- | tools/lib/bpf/bpf_core_read.h | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/tools/lib/bpf/bpf_core_read.h b/tools/lib/bpf/bpf_core_read.h index c0e13cdf9660..b997c68bd945 100644 --- a/tools/lib/bpf/bpf_core_read.h +++ b/tools/lib/bpf/bpf_core_read.h @@ -388,7 +388,13 @@ extern void *bpf_rdonly_cast(const void *obj, __u32 btf_id) __ksym __weak; #define ___arrow10(a, b, c, d, e, f, g, h, i, j) a->b->c->d->e->f->g->h->i->j #define ___arrow(...) ___apply(___arrow, ___narg(__VA_ARGS__))(__VA_ARGS__) +#if defined(__clang__) && (__clang_major__ >= 19) +#define ___type(...) __typeof_unqual__(___arrow(__VA_ARGS__)) +#elif defined(__GNUC__) && (__GNUC__ >= 14) +#define ___type(...) __typeof_unqual__(___arrow(__VA_ARGS__)) +#else #define ___type(...) typeof(___arrow(__VA_ARGS__)) +#endif #define ___read(read_fn, dst, src_type, src, accessor) \ read_fn((void *)(dst), sizeof(*(dst)), &((src_type)(src))->accessor) |