From 5902da6d8a523ed468ea1f28e001c7d5f30c042d Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Wed, 9 Aug 2023 10:34:29 +0200 Subject: [PATCH] libbpf: Add uprobe multi link support to bpf_program__attach_usdt Adding support for usdt_manager_attach_usdt to use uprobe_multi link to attach to usdt probes. The uprobe_multi support is detected before the usdt program is loaded and its expected_attach_type is set accordingly. If uprobe_multi support is detected the usdt_manager_attach_usdt gathers uprobes info and calls bpf_program__attach_uprobe to create all needed uprobes. If uprobe_multi support is not detected the old behaviour stays. Also adding usdt.s program section for sleepable usdt probes. Signed-off-by: Jiri Olsa Link: https://lore.kernel.org/r/20230809083440.3209381-18-jolsa@kernel.org Signed-off-by: Alexei Starovoitov --- tools/lib/bpf/libbpf.c | 13 ++++++- tools/lib/bpf/usdt.c | 86 ++++++++++++++++++++++++++++++++++-------- 2 files changed, 82 insertions(+), 17 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 07b6cbe70059..b8afe2f5bc93 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -367,6 +367,8 @@ enum sec_def_flags { SEC_SLEEPABLE = 8, /* BPF program support non-linear XDP buffer */ SEC_XDP_FRAGS = 16, + /* Setup proper attach type for usdt probes. */ + SEC_USDT = 32, }; struct bpf_sec_def { @@ -6828,6 +6830,10 @@ static int libbpf_prepare_prog_load(struct bpf_program *prog, if (prog->type == BPF_PROG_TYPE_XDP && (def & SEC_XDP_FRAGS)) opts->prog_flags |= BPF_F_XDP_HAS_FRAGS; + /* special check for usdt to use uprobe_multi link */ + if ((def & SEC_USDT) && kernel_supports(prog->obj, FEAT_UPROBE_MULTI_LINK)) + prog->expected_attach_type = BPF_TRACE_UPROBE_MULTI; + if ((def & SEC_ATTACH_BTF) && !prog->attach_btf_id) { int btf_obj_fd = 0, btf_type_id = 0, err; const char *attach_name; @@ -6896,7 +6902,6 @@ static int bpf_object_load_prog(struct bpf_object *obj, struct bpf_program *prog if (!insns || !insns_cnt) return -EINVAL; - load_attr.expected_attach_type = prog->expected_attach_type; if (kernel_supports(obj, FEAT_PROG_NAME)) prog_name = prog->name; load_attr.attach_prog_fd = prog->attach_prog_fd; @@ -6932,6 +6937,9 @@ static int bpf_object_load_prog(struct bpf_object *obj, struct bpf_program *prog insns_cnt = prog->insns_cnt; } + /* allow prog_prepare_load_fn to change expected_attach_type */ + load_attr.expected_attach_type = prog->expected_attach_type; + if (obj->gen_loader) { bpf_gen__prog_load(obj->gen_loader, prog->type, prog->name, license, insns, insns_cnt, &load_attr, @@ -8759,7 +8767,8 @@ static const struct bpf_sec_def section_defs[] = { SEC_DEF("uretprobe.multi.s+", KPROBE, BPF_TRACE_UPROBE_MULTI, SEC_SLEEPABLE, attach_uprobe_multi), SEC_DEF("ksyscall+", KPROBE, 0, SEC_NONE, attach_ksyscall), SEC_DEF("kretsyscall+", KPROBE, 0, SEC_NONE, attach_ksyscall), - SEC_DEF("usdt+", KPROBE, 0, SEC_NONE, attach_usdt), + SEC_DEF("usdt+", KPROBE, 0, SEC_USDT, attach_usdt), + SEC_DEF("usdt.s+", KPROBE, 0, SEC_USDT | SEC_SLEEPABLE, attach_usdt), SEC_DEF("tc/ingress", SCHED_CLS, BPF_TCX_INGRESS, SEC_NONE), /* alias for tcx */ SEC_DEF("tc/egress", SCHED_CLS, BPF_TCX_EGRESS, SEC_NONE), /* alias for tcx */ SEC_DEF("tcx/ingress", SCHED_CLS, BPF_TCX_INGRESS, SEC_NONE), diff --git a/tools/lib/bpf/usdt.c b/tools/lib/bpf/usdt.c index 8322337ab65b..93794f01bb67 100644 --- a/tools/lib/bpf/usdt.c +++ b/tools/lib/bpf/usdt.c @@ -250,6 +250,7 @@ struct usdt_manager { bool has_bpf_cookie; bool has_sema_refcnt; + bool has_uprobe_multi; }; struct usdt_manager *usdt_manager_new(struct bpf_object *obj) @@ -284,6 +285,11 @@ struct usdt_manager *usdt_manager_new(struct bpf_object *obj) */ man->has_sema_refcnt = faccessat(AT_FDCWD, ref_ctr_sysfs_path, F_OK, AT_EACCESS) == 0; + /* + * Detect kernel support for uprobe multi link to be used for attaching + * usdt probes. + */ + man->has_uprobe_multi = kernel_supports(obj, FEAT_UPROBE_MULTI_LINK); return man; } @@ -808,6 +814,8 @@ struct bpf_link_usdt { long abs_ip; struct bpf_link *link; } *uprobes; + + struct bpf_link *multi_link; }; static int bpf_link_usdt_detach(struct bpf_link *link) @@ -816,6 +824,9 @@ static int bpf_link_usdt_detach(struct bpf_link *link) struct usdt_manager *man = usdt_link->usdt_man; int i; + bpf_link__destroy(usdt_link->multi_link); + + /* When having multi_link, uprobe_cnt is 0 */ for (i = 0; i < usdt_link->uprobe_cnt; i++) { /* detach underlying uprobe link */ bpf_link__destroy(usdt_link->uprobes[i].link); @@ -946,11 +957,13 @@ struct bpf_link *usdt_manager_attach_usdt(struct usdt_manager *man, const struct const char *usdt_provider, const char *usdt_name, __u64 usdt_cookie) { + unsigned long *offsets = NULL, *ref_ctr_offsets = NULL; int i, err, spec_map_fd, ip_map_fd; LIBBPF_OPTS(bpf_uprobe_opts, opts); struct hashmap *specs_hash = NULL; struct bpf_link_usdt *link = NULL; struct usdt_target *targets = NULL; + __u64 *cookies = NULL; struct elf_fd elf_fd; size_t target_cnt; @@ -997,10 +1010,21 @@ struct bpf_link *usdt_manager_attach_usdt(struct usdt_manager *man, const struct link->link.detach = &bpf_link_usdt_detach; link->link.dealloc = &bpf_link_usdt_dealloc; - link->uprobes = calloc(target_cnt, sizeof(*link->uprobes)); - if (!link->uprobes) { - err = -ENOMEM; - goto err_out; + if (man->has_uprobe_multi) { + offsets = calloc(target_cnt, sizeof(*offsets)); + cookies = calloc(target_cnt, sizeof(*cookies)); + ref_ctr_offsets = calloc(target_cnt, sizeof(*ref_ctr_offsets)); + + if (!offsets || !ref_ctr_offsets || !cookies) { + err = -ENOMEM; + goto err_out; + } + } else { + link->uprobes = calloc(target_cnt, sizeof(*link->uprobes)); + if (!link->uprobes) { + err = -ENOMEM; + goto err_out; + } } for (i = 0; i < target_cnt; i++) { @@ -1041,20 +1065,48 @@ struct bpf_link *usdt_manager_attach_usdt(struct usdt_manager *man, const struct goto err_out; } - opts.ref_ctr_offset = target->sema_off; - opts.bpf_cookie = man->has_bpf_cookie ? spec_id : 0; - uprobe_link = bpf_program__attach_uprobe_opts(prog, pid, path, - target->rel_ip, &opts); - err = libbpf_get_error(uprobe_link); - if (err) { - pr_warn("usdt: failed to attach uprobe #%d for '%s:%s' in '%s': %d\n", - i, usdt_provider, usdt_name, path, err); + if (man->has_uprobe_multi) { + offsets[i] = target->rel_ip; + ref_ctr_offsets[i] = target->sema_off; + cookies[i] = spec_id; + } else { + opts.ref_ctr_offset = target->sema_off; + opts.bpf_cookie = man->has_bpf_cookie ? spec_id : 0; + uprobe_link = bpf_program__attach_uprobe_opts(prog, pid, path, + target->rel_ip, &opts); + err = libbpf_get_error(uprobe_link); + if (err) { + pr_warn("usdt: failed to attach uprobe #%d for '%s:%s' in '%s': %d\n", + i, usdt_provider, usdt_name, path, err); + goto err_out; + } + + link->uprobes[i].link = uprobe_link; + link->uprobes[i].abs_ip = target->abs_ip; + link->uprobe_cnt++; + } + } + + if (man->has_uprobe_multi) { + LIBBPF_OPTS(bpf_uprobe_multi_opts, opts_multi, + .ref_ctr_offsets = ref_ctr_offsets, + .offsets = offsets, + .cookies = cookies, + .cnt = target_cnt, + ); + + link->multi_link = bpf_program__attach_uprobe_multi(prog, pid, path, + NULL, &opts_multi); + if (!link->multi_link) { + err = -errno; + pr_warn("usdt: failed to attach uprobe multi for '%s:%s' in '%s': %d\n", + usdt_provider, usdt_name, path, err); goto err_out; } - link->uprobes[i].link = uprobe_link; - link->uprobes[i].abs_ip = target->abs_ip; - link->uprobe_cnt++; + free(offsets); + free(ref_ctr_offsets); + free(cookies); } free(targets); @@ -1063,6 +1115,10 @@ struct bpf_link *usdt_manager_attach_usdt(struct usdt_manager *man, const struct return &link->link; err_out: + free(offsets); + free(ref_ctr_offsets); + free(cookies); + if (link) bpf_link__destroy(&link->link); free(targets);