From 1bf4b05810fe38c5f09973295e8d4234a4fd5d87 Mon Sep 17 00:00:00 2001 From: Quentin Monnet Date: Thu, 17 Jan 2019 15:27:53 +0000 Subject: tools: bpftool: add probes for eBPF program types Introduce probes for supported BPF program types in libbpf, and call it from bpftool to test what types are available on the system. The probe simply consists in loading a very basic program of that type and see if the verifier complains or not. Sample output: # bpftool feature probe kernel ... Scanning eBPF program types... eBPF program_type socket_filter is available eBPF program_type kprobe is available eBPF program_type sched_cls is available ... # bpftool --json --pretty feature probe kernel { ... "program_types": { "have_socket_filter_prog_type": true, "have_kprobe_prog_type": true, "have_sched_cls_prog_type": true, ... } } v5: - In libbpf.map, move global symbol to a new LIBBPF_0.0.2 section. - Rename (non-API function) prog_load() as probe_load(). v3: - Get kernel version for checking kprobes availability from libbpf instead of from bpftool. Do not pass kernel_version as an argument when calling libbpf probes. - Use a switch with all enum values for setting specific program parameters just before probing, so that gcc complains at compile time (-Wswitch-enum) if new prog types were added to the kernel but libbpf was not updated. - Add a comment in libbpf.h about setrlimit() usage to allow many consecutive probe attempts. v2: - Move probes from bpftool to libbpf. - Remove C-style macros output from this patch. Signed-off-by: Quentin Monnet Reviewed-by: Jakub Kicinski Reviewed-by: Stanislav Fomichev Signed-off-by: Alexei Starovoitov --- tools/lib/bpf/libbpf.h | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'tools/lib/bpf/libbpf.h') diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index 5f68d7b75215..8e63821109ab 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -355,6 +355,17 @@ LIBBPF_API const struct bpf_line_info * bpf_prog_linfo__lfind(const struct bpf_prog_linfo *prog_linfo, __u32 insn_off, __u32 nr_skip); +/* + * Probe for supported system features + * + * Note that running many of these probes in a short amount of time can cause + * the kernel to reach the maximal size of lockable memory allowed for the + * user, causing subsequent probes to fail. In this case, the caller may want + * to adjust that limit with setrlimit(). + */ +LIBBPF_API bool bpf_probe_prog_type(enum bpf_prog_type prog_type, + __u32 ifindex); + #ifdef __cplusplus } /* extern "C" */ #endif -- cgit v1.2.3