From 2d3ea5e85dd867712ba8747cb01c2d88376ead5c Mon Sep 17 00:00:00 2001 From: Quentin Monnet Date: Thu, 17 Jan 2019 15:27:55 +0000 Subject: tools: bpftool: add probes for eBPF helper functions Similarly to what was done for program types and map types, add a set of probes to test the availability of the different eBPF helper functions on the current system. For each known program type, all known helpers are tested, in order to establish a compatibility matrix. Output is provided as a set of lists of available helpers, one per program type. Sample output: # bpftool feature probe kernel ... Scanning eBPF helper functions... eBPF helpers supported for program type socket_filter: - bpf_map_lookup_elem - bpf_map_update_elem - bpf_map_delete_elem ... eBPF helpers supported for program type kprobe: - bpf_map_lookup_elem - bpf_map_update_elem - bpf_map_delete_elem ... # bpftool --json --pretty feature probe kernel { ... "helpers": { "socket_filter_available_helpers": ["bpf_map_lookup_elem", \ "bpf_map_update_elem","bpf_map_delete_elem", ... ], "kprobe_available_helpers": ["bpf_map_lookup_elem", \ "bpf_map_update_elem","bpf_map_delete_elem", ... ], ... } } v5: - In libbpf.map, move global symbol to the new LIBBPF_0.0.2 section. v4: - Use "enum bpf_func_id" instead of "__u32" in bpf_probe_helper() declaration for the type of the argument used to pass the id of the helper to probe. - Undef BPF_HELPER_MAKE_ENTRY after using it. v3: - Do not pass kernel version from bpftool to libbpf probes (kernel version for testing program with kprobes is retrieved directly from libbpf). - Dump one list of available helpers per program type (instead of one list of compatible program types per helper). v2: - Move probes from bpftool to libbpf. - Test all program types for each helper, print a list of working prog types for each helper. - Fall back on include/uapi/linux/bpf.h for names and ids of helpers. - 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 --- .../bpf/bpftool/Documentation/bpftool-feature.rst | 4 ++ tools/bpf/bpftool/feature.c | 51 ++++++++++++++++++++++ 2 files changed, 55 insertions(+) (limited to 'tools/bpf') diff --git a/tools/bpf/bpftool/Documentation/bpftool-feature.rst b/tools/bpf/bpftool/Documentation/bpftool-feature.rst index 40ac13c0b782..255e3b3629a0 100644 --- a/tools/bpf/bpftool/Documentation/bpftool-feature.rst +++ b/tools/bpf/bpftool/Documentation/bpftool-feature.rst @@ -30,6 +30,10 @@ DESCRIPTION Keyword **kernel** can be omitted. + Note that when probed, some eBPF helpers (e.g. + **bpf_trace_printk**\ () or **bpf_probe_write_user**\ ()) may + print warnings to kernel logs. + **bpftool feature help** Print short help message. diff --git a/tools/bpf/bpftool/feature.c b/tools/bpf/bpftool/feature.c index cc731475c74b..55c8d215ca44 100644 --- a/tools/bpf/bpftool/feature.c +++ b/tools/bpf/bpftool/feature.c @@ -25,6 +25,13 @@ enum probe_component { COMPONENT_KERNEL, }; +#define BPF_HELPER_MAKE_ENTRY(name) [BPF_FUNC_ ## name] = "bpf_" # name +static const char * const helper_name[] = { + __BPF_FUNC_MAPPER(BPF_HELPER_MAKE_ENTRY) +}; + +#undef BPF_HELPER_MAKE_ENTRY + /* Miscellaneous utility functions */ static bool check_procfs(void) @@ -458,6 +465,44 @@ static void probe_map_type(enum bpf_map_type map_type) print_bool_feature(feat_name, plain_desc, res); } +static void +probe_helpers_for_progtype(enum bpf_prog_type prog_type, bool supported_type) +{ + const char *ptype_name = prog_type_name[prog_type]; + char feat_name[128]; + unsigned int id; + bool res; + + if (json_output) { + sprintf(feat_name, "%s_available_helpers", ptype_name); + jsonw_name(json_wtr, feat_name); + jsonw_start_array(json_wtr); + } else { + printf("eBPF helpers supported for program type %s:", + ptype_name); + } + + for (id = 1; id < ARRAY_SIZE(helper_name); id++) { + if (!supported_type) + res = false; + else + res = bpf_probe_helper(id, prog_type, 0); + + if (json_output) { + if (res) + jsonw_string(json_wtr, helper_name[id]); + } else { + if (res) + printf("\n\t- %s", helper_name[id]); + } + } + + if (json_output) + jsonw_end_array(json_wtr); + else + printf("\n"); +} + static int do_probe(int argc, char **argv) { enum probe_component target = COMPONENT_UNSPEC; @@ -533,6 +578,12 @@ static int do_probe(int argc, char **argv) for (i = BPF_MAP_TYPE_UNSPEC + 1; i < map_type_name_size; i++) probe_map_type(i); + print_end_then_start_section("helpers", + "Scanning eBPF helper functions..."); + + for (i = BPF_PROG_TYPE_UNSPEC + 1; i < ARRAY_SIZE(prog_type_name); i++) + probe_helpers_for_progtype(i, supported_types[i]); + exit_close_json: if (json_output) { /* End current "section" of probes */ -- cgit v1.2.3-59-g8ed1b