The introduced header file linux/version.h in libbpf_probes.c may have a wrong macro KERNEL_VERSION for calculating LINUX_VERSION_CODE in some old kernel (Debian9,10). Below is a version info example from Debian 10. release: 4.19.0-22-amd64 version: #1 SMP Debian 4.19.260-1 (2022-09-29) The macro KERNEL_VERSION is defined to (((a) << 16) + ((b) << 8)) + (c)), which a, b, and c stand for major, minor and patch version. So in example here, the major is 4, minor is 19, patch is 260, the LINUX_VERSION(4, 19, 260) which is 267268 should be matched to LINUX_VERSION_CODE. However, the KERNEL_VERSION_CODE in linux/version.h is defined to 267263. I noticed that the macro KERNEL_VERSION in linux/version.h of some new kernel is defined to (((a) << 16) + ((b) << 8) + ((c) > 255 ? 255 : (c))). And KERNEL_VERSION(4, 19, 260) is equal to 267263 which is the right LINUX_VERSION_CODE. The mismatched LINUX_VERSION_CODE which will cause failing to load kprobe BPF programs in the version check of BPF syscall. The return value of get_kernel_version in libbpf_probes.c should be matched to LINUX_VERSION_CODE by correcting the macro KERNEL_VERSION. Signed-off-by: songrui.771 <songrui.771@xxxxxxxxxxxxx> --- Changes since v1: - reintroduce header file linux/version.h - define a new macro LIBBPF_KERNEL_VERSION to get kernel version rather than KERNEL_VERSION --- tools/lib/bpf/libbpf_probes.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c index 4f3bc968ff8e..5b22a880c7e7 100644 --- a/tools/lib/bpf/libbpf_probes.c +++ b/tools/lib/bpf/libbpf_probes.c @@ -18,6 +18,10 @@ #include "libbpf.h" #include "libbpf_internal.h" +#ifndef LIBBPF_KERNEL_VERSION +#define LIBBPF_KERNEL_VERSION(a, b, c) (((a) << 16) + ((b) << 8) + ((c) > 255 ? 255 : (c))) +#endif + /* On Ubuntu LINUX_VERSION_CODE doesn't correspond to info.release, * but Ubuntu provides /proc/version_signature file, as described at * https://ubuntu.com/kernel, with an example contents below, which we @@ -47,7 +51,7 @@ static __u32 get_ubuntu_kernel_version(void) if (ret != 3) return 0; - return KERNEL_VERSION(major, minor, patch); + return LIBBPF_KERNEL_VERSION(major, minor, patch); } /* On Debian LINUX_VERSION_CODE doesn't correspond to info.release. @@ -74,7 +78,7 @@ static __u32 get_debian_kernel_version(struct utsname *info) if (sscanf(p, "Debian %u.%u.%u", &major, &minor, &patch) != 3) return 0; - return KERNEL_VERSION(major, minor, patch); + return LIBBPF_KERNEL_VERSION(major, minor, patch); } __u32 get_kernel_version(void) @@ -97,7 +101,7 @@ __u32 get_kernel_version(void) if (sscanf(info.release, "%u.%u.%u", &major, &minor, &patch) != 3) return 0; - return KERNEL_VERSION(major, minor, patch); + return LIBBPF_KERNEL_VERSION(major, minor, patch); } static int probe_prog_load(enum bpf_prog_type prog_type, -- 2.39.2 (Apple Git-143)
