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/bpf/bpftool/feature.c | 48 ++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 47 insertions(+), 1 deletion(-) (limited to 'tools/bpf') diff --git a/tools/bpf/bpftool/feature.c b/tools/bpf/bpftool/feature.c index 4a2867439ab7..d6508dde4808 100644 --- a/tools/bpf/bpftool/feature.c +++ b/tools/bpf/bpftool/feature.c @@ -1,6 +1,7 @@ // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) /* Copyright (c) 2019 Netronome Systems, Inc. */ +#include #include #include #include @@ -11,6 +12,7 @@ #include #include +#include #include "main.h" @@ -83,6 +85,17 @@ print_start_section(const char *json_title, const char *plain_title) } } +static void +print_end_then_start_section(const char *json_title, const char *plain_title) +{ + if (json_output) + jsonw_end_object(json_wtr); + else + printf("\n"); + + print_start_section(json_title, plain_title); +} + /* Probing functions */ static int read_procfs(const char *path) @@ -403,9 +416,33 @@ static bool probe_bpf_syscall(void) return res; } +static void probe_prog_type(enum bpf_prog_type prog_type, bool *supported_types) +{ + const char *plain_comment = "eBPF program_type "; + char feat_name[128], plain_desc[128]; + size_t maxlen; + bool res; + + res = bpf_probe_prog_type(prog_type, 0); + + supported_types[prog_type] |= res; + + maxlen = sizeof(plain_desc) - strlen(plain_comment) - 1; + if (strlen(prog_type_name[prog_type]) > maxlen) { + p_info("program type name too long"); + return; + } + + sprintf(feat_name, "have_%s_prog_type", prog_type_name[prog_type]); + sprintf(plain_desc, "%s%s", plain_comment, prog_type_name[prog_type]); + print_bool_feature(feat_name, plain_desc, res); +} + static int do_probe(int argc, char **argv) { enum probe_component target = COMPONENT_UNSPEC; + bool supported_types[128] = {}; + unsigned int i; /* Detection assumes user has sufficient privileges (CAP_SYS_ADMIN). * Let's approximate, and restrict usage to root user only. @@ -460,8 +497,17 @@ static int do_probe(int argc, char **argv) print_start_section("syscall_config", "Scanning system call availability..."); - probe_bpf_syscall(); + if (!probe_bpf_syscall()) + /* bpf() syscall unavailable, don't probe other BPF features */ + goto exit_close_json; + + print_end_then_start_section("program_types", + "Scanning eBPF program types..."); + + for (i = BPF_PROG_TYPE_UNSPEC + 1; i < ARRAY_SIZE(prog_type_name); i++) + probe_prog_type(i, supported_types); +exit_close_json: if (json_output) { /* End current "section" of probes */ jsonw_end_object(json_wtr); -- cgit v1.2.3