libbpf: Improve LINUX_VERSION_CODE detection

Ubuntu reports incorrect kernel version through uname(), which on older
kernels leads to kprobe BPF programs failing to load due to the version
check mismatch.

Accommodate Ubuntu's quirks with LINUX_VERSION_CODE by using
Ubuntu-specific /proc/version_code to fetch major/minor/patch versions
to form LINUX_VERSION_CODE.

While at it, consolide libbpf's kernel version detection code between
libbpf.c and libbpf_probes.c.

  [0] Closes: https://github.com/libbpf/libbpf/issues/421

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211222231003.2334940-1-andrii@kernel.org
This commit is contained in:
Andrii Nakryiko
2021-12-22 15:10:03 -08:00
committed by Andrii Nakryiko
parent 3f592a59d7
commit 0171976dc5
3 changed files with 28 additions and 17 deletions

View File

@@ -48,22 +48,6 @@ static int get_vendor_id(int ifindex)
return strtol(buf, NULL, 0);
}
static int get_kernel_version(void)
{
int version, subversion, patchlevel;
struct utsname utsn;
/* Return 0 on failure, and attempt to probe with empty kversion */
if (uname(&utsn))
return 0;
if (sscanf(utsn.release, "%d.%d.%d",
&version, &subversion, &patchlevel) != 3)
return 0;
return (version << 16) + (subversion << 8) + patchlevel;
}
static int probe_prog_load(enum bpf_prog_type prog_type,
const struct bpf_insn *insns, size_t insns_cnt,
char *log_buf, size_t log_buf_sz,