diff options
| author | Ivan Babrou | 2024-05-20 15:51:49 -0700 |
|---|---|---|
| committer | Andrii Nakryiko | 2024-05-21 10:36:28 -0700 |
| commit | f4aba3471cfb9ccf69b476463f19b4c50fef6b14 (patch) | |
| tree | d450f78e9d0d25957ef384db728470f20837a26c /tools | |
| parent | 6f130e4d4a5f7174f98300376f3994817ad7e21c (diff) | |
bpftool: Un-const bpf_func_info to fix it for llvm 17 and newer
LLVM 17 started treating const structs as constants:
* https://github.com/llvm/llvm-project/commit/0b2d5b967d98
Combined with pointer laundering via ptr_to_u64, which takes a const ptr,
but in reality treats the underlying memory as mutable, this makes clang
always pass zero to btf__type_by_id, which breaks full name resolution.
Disassembly before (LLVM 16) and after (LLVM 17):
- 8b 75 cc mov -0x34(%rbp),%esi
- e8 47 8d 02 00 call 3f5b0 <btf__type_by_id>
+ 31 f6 xor %esi,%esi
+ e8 a9 8c 02 00 call 3f510 <btf__type_by_id>
It's a bigger project to fix this properly (and a question whether LLVM
itself should detect this), but for right now let's just fix bpftool.
For more information, see this thread in bpf mailing list:
* https://lore.kernel.org/bpf/CABWYdi0ymezpYsQsPv7qzpx2fWuTkoD1-wG1eT-9x-TSREFrQg@mail.gmail.com/T/
Fixes: b662000aff84 ("bpftool: Adding support for BTF program names")
Signed-off-by: Ivan Babrou <ivan@cloudflare.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/bpf/20240520225149.5517-1-ivan@cloudflare.com
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/bpf/bpftool/common.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/tools/bpf/bpftool/common.c b/tools/bpf/bpftool/common.c index 958e92acca8e..9b75639434b8 100644 --- a/tools/bpf/bpftool/common.c +++ b/tools/bpf/bpftool/common.c @@ -410,7 +410,7 @@ void get_prog_full_name(const struct bpf_prog_info *prog_info, int prog_fd, { const char *prog_name = prog_info->name; const struct btf_type *func_type; - const struct bpf_func_info finfo = {}; + struct bpf_func_info finfo = {}; struct bpf_prog_info info = {}; __u32 info_len = sizeof(info); struct btf *prog_btf = NULL; |