From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-187.mta1.migadu.com (out-187.mta1.migadu.com [95.215.58.187]) (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 B62C43E022E for ; Mon, 13 Jul 2026 15:41:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.187 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783957278; cv=none; b=L8XJNS1G8xET3tvsb0AfeKtbPvIJoLXT0sz3EKluFTgw9uEyXB1YCgra8U7AX1XdvOie6pIN8nxbk9NjMEti07T2ELuQcCKMODHcEFVJhhTMWRGf26bv9G93HxLUApbM2PckJ59b+n3iGVGhyBzxaU/s6/uuNXX2qVHDTXMwJ24= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783957278; c=relaxed/simple; bh=5Gs9lpB29potX4QnrvDusLVJ/aaMcUDBRLbQ9GJSD5k=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=rt4mt4oTmNd175jNfg/RiWwz8MjSHMW2/8nHplh4eNQyceVNUX1ii9qfSi0jUYxguFF8BuSAfxa8TkjsZlyG7UXaHy+xtMTL9xUawjWfzLKV89Hd2F8Pnk33AGJULLRBrJYYOlbPu3kdUxYYm8ppnY5NLAhy0UblE3Y2yZdZnP4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=MsCFmQmV; arc=none smtp.client-ip=95.215.58.187 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="MsCFmQmV" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1783957274; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=hzeBVrq6hHQ0NkIFbRun2A7rrCztpk43QeGTJlPzK+w=; b=MsCFmQmVppb158pOGcSHmN3ZPT7M7IXnKgKGVKqyFo7zDokyiPPw1vANv9jHZr84IUXfNL WZkiek8ldyz29b+dXK0e1pHCUsvtC5kG5wvPalx2KCpwJWSPkvNvi9dqDWirSRik1u6YCE c92xprpFE4RjYFJDMk8Pqd6ZZr79SYM= From: Leon Hwang To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Kumar Kartikeya Dwivedi , Song Liu , Yonghong Song , Jiri Olsa , John Fastabend , Quentin Monnet , Shuah Khan , Leon Hwang , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, kernel-patches-bot@fb.com Subject: [PATCH bpf-next v9 5/9] bpftool: Generate skeleton for global percpu data Date: Mon, 13 Jul 2026 23:40:20 +0800 Message-ID: <20260713154024.30851-6-leon.hwang@linux.dev> In-Reply-To: <20260713154024.30851-1-leon.hwang@linux.dev> References: <20260713154024.30851-1-leon.hwang@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT Enhance bpftool to generate skeletons that properly handle global percpu variables. The generated skeleton now includes a dedicated structure for percpu data, allowing users to initialize and access percpu variables more efficiently. For global percpu variables, the skeleton now includes a nested structure, e.g.: struct test_global_percpu_data { struct bpf_object_skeleton *skeleton; struct bpf_object *obj; struct { struct bpf_map *percpu; } maps; // ... struct test_global_percpu_data__percpu { int data; char run; struct { char set; int i; int nums[7]; } struct_data; int nums[7]; } *percpu; // ... }; * The "struct test_global_percpu_data__percpu *percpu" points to initialized data, which is actually "maps.percpu->mmaped". * Before loading the skeleton, updating the "struct test_global_percpu_data__percpu *percpu" modifies the initial value of the corresponding global percpu variables. * After loading the skeleton, "maps.percpu->mmaped" has been marked as read-only in libbpf. If users want to update the global percpu variables, they have to update the "maps.percpu" map instead. * For lightweight skeleton, "lskel->percpu" will be protected by "mprotect(p, sz, PROT_READ)". * For subskeleton, those variables of global percpu data will be skipped. Acked-by: Quentin Monnet Assisted-by: Codex:gpt-5.5-xhigh Signed-off-by: Leon Hwang --- tools/bpf/bpftool/gen.c | 76 +++++++++++++++++++++++++++-------- tools/lib/bpf/skel_internal.h | 24 ++++++++++- 2 files changed, 81 insertions(+), 19 deletions(-) diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c index a01d06d22d1a..b60db1108149 100644 --- a/tools/bpf/bpftool/gen.c +++ b/tools/bpf/bpftool/gen.c @@ -101,6 +101,12 @@ static bool get_map_ident(const struct bpf_map *map, char *buf, size_t buf_sz) return true; } + if (bpf_map__type(map) == BPF_MAP_TYPE_PERCPU_ARRAY) { + snprintf(buf, buf_sz, "%s", name + 1); + sanitize_identifier(buf); + return true; + } + for (i = 0, n = ARRAY_SIZE(sfxs); i < n; i++) { const char *sfx = sfxs[i], *p; @@ -117,7 +123,7 @@ static bool get_map_ident(const struct bpf_map *map, char *buf, size_t buf_sz) static bool get_datasec_ident(const char *sec_name, char *buf, size_t buf_sz) { - static const char *pfxs[] = { ".data", ".rodata", ".bss", ".kconfig" }; + static const char *pfxs[] = { ".data", ".rodata", ".bss", ".percpu", ".kconfig" }; int i, n; /* recognize hard coded LLVM section name */ @@ -254,7 +260,7 @@ static const struct btf_type *find_type_for_map(struct btf *btf, const char *map return NULL; } -static bool is_mmapable_map(const struct bpf_map *map, char *buf, size_t sz) +static bool is_skel_data(const struct bpf_map *map, char *buf, size_t sz) { size_t tmp_sz; @@ -263,13 +269,19 @@ static bool is_mmapable_map(const struct bpf_map *map, char *buf, size_t sz) return true; } - if (!bpf_map__is_internal(map) || !(bpf_map__map_flags(map) & BPF_F_MMAPABLE)) + if (!bpf_map__is_internal(map)) return false; if (!get_map_ident(map, buf, sz)) return false; - return true; + if (bpf_map__map_flags(map) & BPF_F_MMAPABLE) + return true; + + if (bpf_map__type(map) == BPF_MAP_TYPE_PERCPU_ARRAY) + return true; + + return false; } static int codegen_datasecs(struct bpf_object *obj, const char *obj_name) @@ -286,8 +298,11 @@ static int codegen_datasecs(struct bpf_object *obj, const char *obj_name) return -errno; bpf_object__for_each_map(map, obj) { - /* only generate definitions for memory-mapped internal maps */ - if (!is_mmapable_map(map, map_ident, sizeof(map_ident))) + /* + * Only generate definitions for internal maps that have + * mmapped data. + */ + if (!is_skel_data(map, map_ident, sizeof(map_ident))) continue; sec = find_type_for_map(btf, map_ident); @@ -339,8 +354,14 @@ static int codegen_subskel_datasecs(struct bpf_object *obj, const char *obj_name return -errno; bpf_object__for_each_map(map, obj) { - /* only generate definitions for memory-mapped internal maps */ - if (!is_mmapable_map(map, map_ident, sizeof(map_ident))) + /* + * Only generate definitions for internal maps that have + * mmapped data. + */ + if (!is_skel_data(map, map_ident, sizeof(map_ident))) + continue; + + if (bpf_map__type(map) == BPF_MAP_TYPE_PERCPU_ARRAY) continue; sec = find_type_for_map(btf, map_ident); @@ -493,7 +514,10 @@ static size_t bpf_map_mmap_sz(const struct bpf_map *map) return map_sz; } -/* Emit type size asserts for all top-level fields in memory-mapped internal maps. */ +/* + * Emit type size asserts for all top-level fields in internal maps that + * have mmaped data. + */ static void codegen_asserts(struct bpf_object *obj, const char *obj_name) { struct btf *btf = bpf_object__btf(obj); @@ -517,7 +541,7 @@ static void codegen_asserts(struct bpf_object *obj, const char *obj_name) ", obj_name); bpf_object__for_each_map(map, obj) { - if (!is_mmapable_map(map, map_ident, sizeof(map_ident))) + if (!is_skel_data(map, map_ident, sizeof(map_ident))) continue; sec = find_type_for_map(btf, map_ident); @@ -669,7 +693,8 @@ static void codegen_destroy(struct bpf_object *obj, const char *obj_name) if (!get_map_ident(map, ident, sizeof(ident))) continue; if (bpf_map__is_internal(map) && - (bpf_map__map_flags(map) & BPF_F_MMAPABLE)) + ((bpf_map__map_flags(map) & BPF_F_MMAPABLE) || + bpf_map__type(map) == BPF_MAP_TYPE_PERCPU_ARRAY)) printf("\tskel_free_map_data(skel->%1$s, skel->maps.%1$s.initial_value, %2$zu);\n", ident, bpf_map_mmap_sz(map)); codegen("\ @@ -741,7 +766,7 @@ static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *h const void *mmap_data = NULL; size_t mmap_size = 0; - if (!is_mmapable_map(map, ident, sizeof(ident))) + if (!is_skel_data(map, ident, sizeof(ident))) continue; codegen("\ @@ -849,8 +874,22 @@ static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *h bpf_object__for_each_map(map, obj) { const char *mmap_flags; - if (!is_mmapable_map(map, ident, sizeof(ident))) + if (!is_skel_data(map, ident, sizeof(ident))) + continue; + + if (bpf_map__type(map) == BPF_MAP_TYPE_PERCPU_ARRAY) { + codegen("\ + \n\ + err = skel_protect_map_data(skel->%1$s, &skel->maps.%1$s.initial_value, %2$zd);\n\ + if (err) \n\ + return err; \n\ + #ifdef __KERNEL__ \n\ + skel->%1$s = NULL; \n\ + #endif \n\ + ", + ident, bpf_map_mmap_sz(map)); continue; + } if (bpf_map__map_flags(map) & BPF_F_RDONLY_PROG) mmap_flags = "PROT_READ"; @@ -955,8 +994,7 @@ codegen_maps_skeleton(struct bpf_object *obj, size_t map_cnt, bool mmaped, bool map->map = &obj->maps.%s; \n\ ", i, bpf_map__name(map), ident); - /* memory-mapped internal maps */ - if (mmaped && is_mmapable_map(map, ident, sizeof(ident))) { + if (mmaped && is_skel_data(map, ident, sizeof(ident))) { printf("\tmap->mmaped = (void **)&obj->%s;\n", ident); } @@ -1740,7 +1778,9 @@ static int do_subskeleton(int argc, char **argv) /* Also count all maps that have a name */ map_cnt++; - if (!is_mmapable_map(map, ident, sizeof(ident))) + if (!is_skel_data(map, ident, sizeof(ident))) + continue; + if (bpf_map__type(map) == BPF_MAP_TYPE_PERCPU_ARRAY) continue; map_type_id = bpf_map__btf_value_type_id(map); @@ -1863,7 +1903,9 @@ static int do_subskeleton(int argc, char **argv) /* walk through each symbol and emit the runtime representation */ bpf_object__for_each_map(map, obj) { - if (!is_mmapable_map(map, ident, sizeof(ident))) + if (!is_skel_data(map, ident, sizeof(ident))) + continue; + if (bpf_map__type(map) == BPF_MAP_TYPE_PERCPU_ARRAY) continue; map_type_id = bpf_map__btf_value_type_id(map); diff --git a/tools/lib/bpf/skel_internal.h b/tools/lib/bpf/skel_internal.h index 53fee53d36d5..1f3f332dffbe 100644 --- a/tools/lib/bpf/skel_internal.h +++ b/tools/lib/bpf/skel_internal.h @@ -131,8 +131,10 @@ static inline void skel_free_map_data(void *p, __u64 addr, size_t sz) { if (addr != ~0ULL) kvfree(p); - /* When addr == ~0ULL the 'p' points to - * ((struct bpf_array *)map)->value. See skel_finalize_map_data. + /* + * When addr == ~0ULL the init buffer has already been released. + * For skel_finalize_map_data(), 'p' points to + * ((struct bpf_array *)map)->value. */ } @@ -170,6 +172,15 @@ static inline void *skel_finalize_map_data(__u64 *init_val, size_t mmap_sz, int return addr; } +static inline int skel_protect_map_data(void *p, __u64 *init_val, size_t sz) +{ + (void)sz; + + kvfree(p); + *init_val = ~0ULL; + return 0; +} + #else static inline void *skel_alloc(size_t size) @@ -208,6 +219,15 @@ static inline void *skel_finalize_map_data(__u64 *init_val, size_t mmap_sz, int return NULL; return addr; } + +static inline int skel_protect_map_data(void *p, __u64 *init_val, size_t sz) +{ + (void)init_val; + + if (mprotect(p, sz, PROT_READ)) + return -errno; + return 0; +} #endif static inline int skel_closenz(int fd) -- 2.55.0