From patchwork Fri Nov 3 23:21:56 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kui-Feng Lee X-Patchwork-Id: 13445259 X-Patchwork-Delegate: bpf@iogearbox.net Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6453F262A6 for ; Fri, 3 Nov 2023 23:22:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="QA9FJhR6" Received: from mail-oo1-xc32.google.com (mail-oo1-xc32.google.com [IPv6:2607:f8b0:4864:20::c32]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 140B3B7 for ; Fri, 3 Nov 2023 16:22:22 -0700 (PDT) Received: by mail-oo1-xc32.google.com with SMTP id 006d021491bc7-5842ea6f4d5so1433261eaf.2 for ; Fri, 03 Nov 2023 16:22:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1699053741; x=1699658541; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=GMLmcQzRw+g3bs33c0PgnlIa2CJCu2fyueTsDXsP0lI=; b=QA9FJhR6mKVmgv7EoF6ZcW+4bLLQysKPkMEWrs5Yb8PgLyYGTAsMID9zjkeW3xDSJ4 VF5LerWfKDpirNL2jXByUm+ZSoBetRk1SSOFEwKy5K4lOVNHgEN6uOBIiA6nKIrEs2Rl jaNgfJwBEnTOVSkBZa+x0a+3l6yOlXSFFPqFhrqy8/mM2RlhixMVcMVpPB2ISy1vcGOC oGDMx20Ccd/rSHKPMof3dIeI6j7urTGTRsFvAOfdjCKSUd4aS3pvhMN2RZCuPdkcF4xb SCYyRldQP/TuSiOrFBoyar0ogZM5/iacNe6Z9tqqK7uOiNujRP0PS0hFq6p9nnU2GcAo Ql0g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1699053741; x=1699658541; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=GMLmcQzRw+g3bs33c0PgnlIa2CJCu2fyueTsDXsP0lI=; b=hlrwxnsDoPqQPaSxGYEsRDH62RhmXJVJOijLAMGnm/FNMpSbmBcRVYioD6anmFEkWu VTb6h8HpiNnecJDLvimpwy9WcZDKVywfTbZXOweWC96JnGtETV7GGg4dNBAHm9QLxeu9 fdeo1Nau68yPnIRHPiGTb8LaBmtiiFq9pnxpx9fw1bEIHkjOZgwLgdy/JFcBvARb/zZy tAGNf2rjup/ycFgwDpwUSeGHm3nqsNM+9msrr18zzyoVtKoUz+0moSjmywn+ExPb5FqA aJTqvtJggR+I2BnGoWkAZ68ZhgTAHHKWhoQJgfKntcEg09E3+g7k3gAEWhPTD77+1Csx pfcw== X-Gm-Message-State: AOJu0YxtSDqUkWVSn8Nng97WSO1o82nuYWlnFufE6rnfUSnq6/yHHNuv 3HBKqAywRapJ82zFjMFAN9MMmO2tx9g= X-Google-Smtp-Source: AGHT+IF1avbY3Wcr6XIAzwFqiVXcprCGXfBoYGdztNjyqb6e4XlAmZU1y+IhCWDhJSzanWraUo+abw== X-Received: by 2002:a4a:a787:0:b0:57b:92f2:1f64 with SMTP id l7-20020a4aa787000000b0057b92f21f64mr20258753oom.8.1699053741046; Fri, 03 Nov 2023 16:22:21 -0700 (PDT) Received: from kickker.attlocal.net ([2600:1700:6cf8:1240:287:9d8c:4ad:9459]) by smtp.gmail.com with ESMTPSA id 186-20020a4a14c3000000b0057b8baf00bbsm532288ood.22.2023.11.03.16.22.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 03 Nov 2023 16:22:20 -0700 (PDT) From: thinker.li@gmail.com To: bpf@vger.kernel.org, ast@kernel.org, martin.lau@linux.dev, song@kernel.org, kernel-team@meta.com, andrii@kernel.org, drosen@google.com Cc: sinquersw@gmail.com, kuifeng@meta.com, Kui-Feng Lee Subject: [PATCH bpf-next v10 07/13] bpf: pass attached BTF to the bpf_struct_ops subsystem Date: Fri, 3 Nov 2023 16:21:56 -0700 Message-Id: <20231103232202.3664407-8-thinker.li@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231103232202.3664407-1-thinker.li@gmail.com> References: <20231103232202.3664407-1-thinker.li@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net From: Kui-Feng Lee Every kernel module has its BTF, comprising information on types defined in the module. The BTF fd (attr->value_type_btf_obj_fd) passed from userspace helps the bpf_struct_ops to lookup type information and description of the struct_ops type, which is necessary for parsing the layout of map element values and registering maps. The descriptions are looked up by matching a type id (attr->btf_vmlinux_value_type_id) against bpf_struct_ops_desc(s) defined in a BTF. If the struct_ops type is defined in a module, the bpf_struct_ops needs to know the module BTF to lookup the bpf_struct_ops_desc. The bpf_prog includes attach_btf in aux which is passed along with the bpf_attr when loading the program. The purpose of attach_btf is to determine the btf type of attach_btf_id. The attach_btf_id is then used to identify the traced function for a trace program. In the case of struct_ops programs, it is used to identify the struct_ops type of the struct_ops object that a program is attached to. Signed-off-by: Kui-Feng Lee --- include/uapi/linux/bpf.h | 5 +++++ kernel/bpf/bpf_struct_ops.c | 31 ++++++++++++++++++++++++++----- kernel/bpf/syscall.c | 2 +- kernel/bpf/verifier.c | 9 ++++++--- tools/include/uapi/linux/bpf.h | 5 +++++ 5 files changed, 43 insertions(+), 9 deletions(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 0f6cdf52b1da..fd20c52606b2 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -1398,6 +1398,11 @@ union bpf_attr { * to using 5 hash functions). */ __u64 map_extra; + + __u32 value_type_btf_obj_fd; /* fd pointing to a BTF + * type data for + * btf_vmlinux_value_type_id. + */ }; struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */ diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c index 4ba6181ed1c4..8aaaa5121a56 100644 --- a/kernel/bpf/bpf_struct_ops.c +++ b/kernel/bpf/bpf_struct_ops.c @@ -635,6 +635,7 @@ static void __bpf_struct_ops_map_free(struct bpf_map *map) bpf_jit_uncharge_modmem(PAGE_SIZE); } bpf_map_area_free(st_map->uvalue); + btf_put(st_map->btf); bpf_map_area_free(st_map); } @@ -675,11 +676,24 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr) struct bpf_struct_ops_map *st_map; const struct btf_type *t, *vt; struct bpf_map *map; + struct btf *btf; int ret; - st_ops_desc = bpf_struct_ops_find_value(btf_vmlinux, attr->btf_vmlinux_value_type_id); - if (!st_ops_desc) - return ERR_PTR(-ENOTSUPP); + if (attr->value_type_btf_obj_fd) { + /* The map holds btf for its whole life time. */ + btf = btf_get_by_fd(attr->value_type_btf_obj_fd); + if (IS_ERR(btf)) + return ERR_PTR(PTR_ERR(btf)); + } else { + btf = btf_vmlinux; + btf_get(btf); + } + + st_ops_desc = bpf_struct_ops_find_value(btf, attr->btf_vmlinux_value_type_id); + if (!st_ops_desc) { + ret = -ENOTSUPP; + goto errout; + } vt = st_ops_desc->value_type; if (attr->value_size != vt->size) @@ -697,6 +711,7 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr) if (!st_map) return ERR_PTR(-ENOMEM); + st_map->btf = btf; st_map->st_ops_desc = st_ops_desc; map = &st_map->map; @@ -725,13 +740,19 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr) return ERR_PTR(-ENOMEM); } - st_map->btf = btf_vmlinux; - mutex_init(&st_map->lock); set_vm_flush_reset_perms(st_map->image); bpf_map_init_from_attr(map, attr); return map; + +errout_free: + __bpf_struct_ops_map_free(map); + btf = NULL; /* has been released */ +errout: + btf_put(btf); + + return ERR_PTR(ret); } static u64 bpf_struct_ops_map_mem_usage(const struct bpf_map *map) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 0ed286b8a0f0..974651fe2bee 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1096,7 +1096,7 @@ static int map_check_btf(struct bpf_map *map, const struct btf *btf, return ret; } -#define BPF_MAP_CREATE_LAST_FIELD map_extra +#define BPF_MAP_CREATE_LAST_FIELD value_type_btf_obj_fd /* called via syscall */ static int map_create(union bpf_attr *attr) { diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index bdd166cab977..3f446f76d4bf 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -20086,6 +20086,7 @@ static int check_struct_ops_btf_id(struct bpf_verifier_env *env) const struct btf_member *member; struct bpf_prog *prog = env->prog; u32 btf_id, member_idx; + struct btf *btf; const char *mname; if (!prog->gpl_compatible) { @@ -20093,8 +20094,10 @@ static int check_struct_ops_btf_id(struct bpf_verifier_env *env) return -EINVAL; } + btf = prog->aux->attach_btf; + btf_id = prog->aux->attach_btf_id; - st_ops_desc = bpf_struct_ops_find(btf_vmlinux, btf_id); + st_ops_desc = bpf_struct_ops_find(btf, btf_id); if (!st_ops_desc) { verbose(env, "attach_btf_id %u is not a supported struct\n", btf_id); @@ -20111,8 +20114,8 @@ static int check_struct_ops_btf_id(struct bpf_verifier_env *env) } member = &btf_type_member(t)[member_idx]; - mname = btf_name_by_offset(btf_vmlinux, member->name_off); - func_proto = btf_type_resolve_func_ptr(btf_vmlinux, member->type, + mname = btf_name_by_offset(btf, member->name_off); + func_proto = btf_type_resolve_func_ptr(btf, member->type, NULL); if (!func_proto) { verbose(env, "attach to invalid member %s(@idx %u) of struct %s\n", diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 0f6cdf52b1da..fd20c52606b2 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -1398,6 +1398,11 @@ union bpf_attr { * to using 5 hash functions). */ __u64 map_extra; + + __u32 value_type_btf_obj_fd; /* fd pointing to a BTF + * type data for + * btf_vmlinux_value_type_id. + */ }; struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */