6.10-stable review patch. If anyone has any objections, please let me know.
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From: Ivan Babrou ivan@cloudflare.com
[ Upstream commit f4aba3471cfb9ccf69b476463f19b4c50fef6b14 ]
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-TSREF...
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 Signed-off-by: Sasha Levin sashal@kernel.org --- tools/bpf/bpftool/common.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/bpf/bpftool/common.c b/tools/bpf/bpftool/common.c index 958e92acca8e2..9b75639434b81 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;