This is a note to let you know that I've just added the patch titled
bpftool: Un-const bpf_func_info to fix it for llvm 17 and newer
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
bpftool-un-const-bpf_func_info-to-fix-it-for-llvm-17.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit b2c009d346f476b4c95bcaf52bdc1f3111c53f14
Author: Ivan Babrou <ivan@xxxxxxxxxxxxxx>
Date: Mon May 20 15:51:49 2024 -0700
bpftool: Un-const bpf_func_info to fix it for llvm 17 and newer
[ 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-TSREFrQg@xxxxxxxxxxxxxx/T/
Fixes: b662000aff84 ("bpftool: Adding support for BTF program names")
Signed-off-by: Ivan Babrou <ivan@xxxxxxxxxxxxxx>
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Acked-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Acked-by: Yonghong Song <yonghong.song@xxxxxxxxx>
Link: https://lore.kernel.org/bpf/20240520225149.5517-1-ivan@xxxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/tools/bpf/bpftool/common.c b/tools/bpf/bpftool/common.c
index e7a11cff7245a..db02b000fbebd 100644
--- a/tools/bpf/bpftool/common.c
+++ b/tools/bpf/bpftool/common.c
@@ -333,7 +333,7 @@ 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;
