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libbpf: Fix CO-RE relocs against .text section

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bpf_object__find_program_by_title(), used by CO-RE relocation code, doesn't
return .text "BPF program", if it is a function storage for sub-programs.
Because of that, any CO-RE relocation in helper non-inlined functions will
fail. Fix this by searching for .text-corresponding BPF program manually.

Adjust one of bpf_iter selftest to exhibit this pattern.

Fixes: ddc7c30426 ("libbpf: implement BPF CO-RE offset relocation algorithm")
Reported-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200619230423.691274-1-andriin@fb.com
This commit is contained in:
Andrii Nakryiko 2020-06-19 16:04:22 -07:00 committed by Alexei Starovoitov
parent 4e15507fea
commit 9c82a63cf3
2 changed files with 8 additions and 2 deletions
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8
tools/lib/bpf/libbpf.c
View File

@ -4818,7 +4818,13 @@ bpf_core_reloc_fields(struct bpf_object *obj, const char *targ_btf_path)
err = -EINVAL; err = -EINVAL;
goto out; goto out;
} }
prog = bpf_object__find_program_by_title(obj, sec_name); prog = NULL;
for (i = 0; i < obj->nr_programs; i++) {
if (!strcmp(obj->programs[i].section_name, sec_name)) {
prog = &obj->programs[i];
break;
}
}
if (!prog) { if (!prog) {
pr_warn("failed to find program '%s' for CO-RE offset relocation\n", pr_warn("failed to find program '%s' for CO-RE offset relocation\n",
sec_name); sec_name);

2
tools/testing/selftests/bpf/progs/bpf_iter_netlink.c
View File

@ -25,7 +25,7 @@ struct bpf_iter__netlink {
struct netlink_sock *sk; struct netlink_sock *sk;
} __attribute__((preserve_access_index)); } __attribute__((preserve_access_index));
static inline struct inode *SOCK_INODE(struct socket *socket) static __attribute__((noinline)) struct inode *SOCK_INODE(struct socket *socket)
{ {
return &container_of(socket, struct socket_alloc, socket)->vfs_inode; return &container_of(socket, struct socket_alloc, socket)->vfs_inode;
} }