From patchwork Mon Nov 6 20:12:46 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: 13447453 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 BECD02E63A for ; Mon, 6 Nov 2023 20:13:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ZG2PvN1X" Received: from mail-yw1-x1135.google.com (mail-yw1-x1135.google.com [IPv6:2607:f8b0:4864:20::1135]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 361C610EB for ; Mon, 6 Nov 2023 12:13:11 -0800 (PST) Received: by mail-yw1-x1135.google.com with SMTP id 00721157ae682-59e88a28b98so42719867b3.1 for ; Mon, 06 Nov 2023 12:13:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1699301589; x=1699906389; 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=nqAlLOKNQif6b9Pce867dvcA4+g9SmLIfm6t01dtofw=; b=ZG2PvN1XXI8JcWz8gLSXLEj1EvEp0jUC5Dj6zCt4nmumRCLYBcm/myWcPi8ZKr3YMY y8K4r+3pHV7BOC30fRTCfOzaME16NPZ63mdugcW1XS486IrlgZMjuF4ULMauuLNKqh+w I2xIz4CFQcz4ME4MdnI7ZpoMkLRPTkhqX3y0dI6D+3JUsIa8cs5p478VQHH4sfMeoY1O LaJdecbeOjnc7T8ZXu2kozX9tGa/cRpu/9K65N+kYQRpyykExMvFJVyxCl47bxNgxlS2 F0MJ+ZDvA11uYoOVBORtu8dvW9tE0DhAyECCV6J9z+1oZAWcWniAe1DBINz7gYC+WJg4 YRrQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1699301589; x=1699906389; 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=nqAlLOKNQif6b9Pce867dvcA4+g9SmLIfm6t01dtofw=; b=VN+159uU9/UUVOltz3q4ur7gWsTOseNN8PqWxgaybvgOQD44eDxHplHtFhU27z6Gt5 RdHSvJoYBU49ThjDvuGVuZbrSvPd+vST+jzo74kyWFOltDYGOrSZPaH1U0F7LioC8ir1 4wju0JRIoRTvuo/xiYKGHDEOIcPIUkPnMUxZp870vdCG+qncj2yFP60Nko5YdtL5qA81 cBQNfdpCJJqgKwgTq0zalq4IDpKTOHWdL01o9qVQO30aZK+3CYGgT9L4m61a4OjGhMEV 7OGN1ll7YgtbYGEfTjCSfFuV/bSY0Q+OTfMqf6bumyIaVwbe8PD1JqlrUI9lZMYypet/ Cezw== X-Gm-Message-State: AOJu0YxgX5UTbOTUqjC1ng/oTUnAP+EMXXe1nF5iv9+y+e7Fbnr1RSZc LA0IteGxhFdGLuiuR/vAHTn29azFsQs= X-Google-Smtp-Source: AGHT+IFcX//JA6MvzX9T83rfcAtgUNbN8TZaXFu8H2mFpyO3rrTTkqYiB0nIof2YI4TD6oEeYuDTpQ== X-Received: by 2002:a0d:dbcc:0:b0:5a8:1a54:ba4b with SMTP id d195-20020a0ddbcc000000b005a81a54ba4bmr462758ywe.13.1699301589397; Mon, 06 Nov 2023 12:13:09 -0800 (PST) Received: from kickker.attlocal.net ([2600:1700:6cf8:1240:446d:cdea:6fa5:5630]) by smtp.gmail.com with ESMTPSA id e65-20020a816944000000b0058427045833sm4760611ywc.133.2023.11.06.12.13.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 06 Nov 2023 12:13:08 -0800 (PST) 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 v11 07/13] bpf: pass attached BTF to the bpf_struct_ops subsystem Date: Mon, 6 Nov 2023 12:12:46 -0800 Message-Id: <20231106201252.1568931-8-thinker.li@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231106201252.1568931-1-thinker.li@gmail.com> References: <20231106201252.1568931-1-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 | 57 ++++++++++++++++++++++++---------- kernel/bpf/syscall.c | 2 +- kernel/bpf/verifier.c | 9 ++++-- tools/include/uapi/linux/bpf.h | 5 +++ 5 files changed, 57 insertions(+), 21 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..2fb1b21f989a 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); } @@ -675,15 +676,30 @@ 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) - return ERR_PTR(-EINVAL); + if (attr->value_size != vt->size) { + ret = -EINVAL; + goto errout; + } t = st_ops_desc->type; @@ -694,17 +710,18 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr) (vt->size - sizeof(struct bpf_struct_ops_value)); st_map = bpf_map_area_alloc(st_map_size, NUMA_NO_NODE); - if (!st_map) - return ERR_PTR(-ENOMEM); + if (!st_map) { + ret = -ENOMEM; + goto errout; + } + st_map->btf = btf; st_map->st_ops_desc = st_ops_desc; map = &st_map->map; ret = bpf_jit_charge_modmem(PAGE_SIZE); - if (ret) { - __bpf_struct_ops_map_free(map); - return ERR_PTR(ret); - } + if (ret) + goto errout_free; st_map->image = bpf_jit_alloc_exec(PAGE_SIZE); if (!st_map->image) { @@ -713,25 +730,31 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr) * here. */ bpf_jit_uncharge_modmem(PAGE_SIZE); - __bpf_struct_ops_map_free(map); - return ERR_PTR(-ENOMEM); + ret = -ENOMEM; + goto errout_free; } st_map->uvalue = bpf_map_area_alloc(vt->size, NUMA_NO_NODE); st_map->links = bpf_map_area_alloc(btf_type_vlen(t) * sizeof(struct bpf_links *), NUMA_NO_NODE); if (!st_map->uvalue || !st_map->links) { - __bpf_struct_ops_map_free(map); - return ERR_PTR(-ENOMEM); + ret = -ENOMEM; + goto errout_free; } - 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 */