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author | Martin KaFai Lau <kafai@fb.com> | 2021-02-12 05:10:30 +0300 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-03-04 13:37:33 +0300 |
commit | c8de71a7ae39e5f55b4ef5851387e2661c87f30b (patch) | |
tree | 15ee67fbb21bb4e896c37a522e4d276165af0270 /tools/lib | |
parent | b5f71c9ff1284da6012b402291b31badf91663d9 (diff) | |
download | linux-c8de71a7ae39e5f55b4ef5851387e2661c87f30b.tar.xz |
libbpf: Ignore non function pointer member in struct_ops
[ Upstream commit d2836dddc95d5dd82c7cb23726c97d8c9147f050 ]
When libbpf initializes the kernel's struct_ops in
"bpf_map__init_kern_struct_ops()", it enforces all
pointer types must be a function pointer and rejects
others. It turns out to be too strict. For example,
when directly using "struct tcp_congestion_ops" from vmlinux.h,
it has a "struct module *owner" member and it is set to NULL
in a bpf_tcp_cc.o.
Instead, it only needs to ensure the member is a function
pointer if it has been set (relocated) to a bpf-prog.
This patch moves the "btf_is_func_proto(kern_mtype)" check
after the existing "if (!prog) { continue; }". The original debug
message in "if (!prog) { continue; }" is also removed since it is
no longer valid. Beside, there is a later debug message to tell
which function pointer is set.
The "btf_is_func_proto(mtype)" has already been guaranteed
in "bpf_object__collect_st_ops_relos()" which has been run
before "bpf_map__init_kern_struct_ops()". Thus, this check
is removed.
v2:
- Remove outdated debug message (Andrii)
Remove because there is a later debug message to tell
which function pointer is set.
- Following mtype->type is no longer needed. Remove:
"skip_mods_and_typedefs(btf, mtype->type, &mtype_id)"
- Do "if (!prog)" test before skip_mods_and_typedefs.
Fixes: 590a00888250 ("bpf: libbpf: Add STRUCT_OPS support")
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210212021030.266932-1-kafai@fb.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'tools/lib')
-rw-r--r-- | tools/lib/bpf/libbpf.c | 22 |
1 files changed, 11 insertions, 11 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index ad165e6e74bc..b954db52bb80 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -865,24 +865,24 @@ static int bpf_map__init_kern_struct_ops(struct bpf_map *map, if (btf_is_ptr(mtype)) { struct bpf_program *prog; - mtype = skip_mods_and_typedefs(btf, mtype->type, &mtype_id); + prog = st_ops->progs[i]; + if (!prog) + continue; + kern_mtype = skip_mods_and_typedefs(kern_btf, kern_mtype->type, &kern_mtype_id); - if (!btf_is_func_proto(mtype) || - !btf_is_func_proto(kern_mtype)) { - pr_warn("struct_ops init_kern %s: non func ptr %s is not supported\n", + + /* mtype->type must be a func_proto which was + * guaranteed in bpf_object__collect_st_ops_relos(), + * so only check kern_mtype for func_proto here. + */ + if (!btf_is_func_proto(kern_mtype)) { + pr_warn("struct_ops init_kern %s: kernel member %s is not a func ptr\n", map->name, mname); return -ENOTSUP; } - prog = st_ops->progs[i]; - if (!prog) { - pr_debug("struct_ops init_kern %s: func ptr %s is not set\n", - map->name, mname); - continue; - } - prog->attach_btf_id = kern_type_id; prog->expected_attach_type = kern_member_idx; |