Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754915AbbFLFk6 (ORCPT ); Fri, 12 Jun 2015 01:40:58 -0400 Received: from szxga02-in.huawei.com ([119.145.14.65]:10923 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753024AbbFLFgj (ORCPT ); Fri, 12 Jun 2015 01:36:39 -0400 From: Wang Nan To: , , , , , , , , , , CC: , , , , Subject: [RFC PATCH v7 05/37] bpf tools: Read eBPF object from buffer Date: Fri, 12 Jun 2015 05:35:13 +0000 Message-ID: <1434087345-127225-6-git-send-email-wangnan0@huawei.com> X-Mailer: git-send-email 1.8.3.4 In-Reply-To: <1434087345-127225-1-git-send-email-wangnan0@huawei.com> References: <1434087345-127225-1-git-send-email-wangnan0@huawei.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.107.197.200] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4510 Lines: 160 To support dynamic compiling, this patch allows caller to pass a in-memory buffer to libbpf by bpf_object__open_buffer(). libbpf calls elf_memory() to open it as ELF object file. Because __bpf_object__open() collects all required data and won't need that buffer anymore, libbpf uses that buffer directly instead of clone a new buffer. Caller of libbpf can free that buffer or use it do other things after bpf_object__open_buffer() return. Signed-off-by: Wang Nan --- tools/lib/bpf/libbpf.c | 62 ++++++++++++++++++++++++++++++++++++++++---------- tools/lib/bpf/libbpf.h | 2 ++ 2 files changed, 52 insertions(+), 12 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 197ab5e..8ba6ac6 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -84,6 +84,8 @@ struct bpf_object { */ struct { int fd; + void *obj_buf; + size_t obj_buf_sz; Elf *elf; GElf_Ehdr ehdr; } efile; @@ -91,7 +93,9 @@ struct bpf_object { }; #define obj_elf_valid(o) ((o)->efile.elf) -static struct bpf_object *bpf_object__new(const char *path) +static struct bpf_object *bpf_object__new(const char *path, + void *obj_buf, + size_t obj_buf_sz) { struct bpf_object *obj; @@ -103,6 +107,16 @@ static struct bpf_object *bpf_object__new(const char *path) strcpy(obj->path, path); obj->efile.fd = -1; + + /* + * Caller of this function should also calls + * bpf_object__elf_finish() after data collection to return + * obj_buf to user. If not, we should duplicate the buffer to + * avoid user freeing them before elf finish. + */ + obj->efile.obj_buf = obj_buf; + obj->efile.obj_buf_sz = obj_buf_sz; + return obj; } @@ -116,6 +130,8 @@ static void bpf_object__elf_finish(struct bpf_object *obj) obj->efile.elf = NULL; } zclose(obj->efile.fd); + obj->efile.obj_buf = NULL; + obj->efile.obj_buf_sz = 0; } static int bpf_object__elf_init(struct bpf_object *obj) @@ -128,16 +144,26 @@ static int bpf_object__elf_init(struct bpf_object *obj) return -EEXIST; } - obj->efile.fd = open(obj->path, O_RDONLY); - if (obj->efile.fd < 0) { - pr_warning("failed to open %s: %s\n", obj->path, - strerror(errno)); - return -errno; + if (obj->efile.obj_buf_sz > 0) { + /* + * obj_buf should have been validated by + * bpf_object__open_buffer(). + */ + obj->efile.elf = elf_memory(obj->efile.obj_buf, + obj->efile.obj_buf_sz); + } else { + obj->efile.fd = open(obj->path, O_RDONLY); + if (obj->efile.fd < 0) { + pr_warning("failed to open %s: %s\n", obj->path, + strerror(errno)); + return -errno; + } + + obj->efile.elf = elf_begin(obj->efile.fd, + LIBBPF_ELF_C_READ_MMAP, + NULL); } - obj->efile.elf = elf_begin(obj->efile.fd, - LIBBPF_ELF_C_READ_MMAP, - NULL); if (!obj->efile.elf) { pr_warning("failed to open %s as ELF file\n", obj->path); @@ -167,7 +193,7 @@ errout: } static struct bpf_object * -__bpf_object__open(const char *path) +__bpf_object__open(const char *path, void *obj_buf, size_t obj_buf_sz) { struct bpf_object *obj; @@ -176,7 +202,7 @@ __bpf_object__open(const char *path) return NULL; } - obj = bpf_object__new(path); + obj = bpf_object__new(path, obj_buf, obj_buf_sz); if (!obj) return NULL; @@ -198,7 +224,19 @@ struct bpf_object *bpf_object__open(const char *path) pr_debug("loading %s\n", path); - return __bpf_object__open(path); + return __bpf_object__open(path, NULL, 0); +} + +struct bpf_object *bpf_object__open_buffer(void *obj_buf, + size_t obj_buf_sz) +{ + /* param validation */ + if (!obj_buf || obj_buf_sz <= 0) + return NULL; + + pr_debug("loading object from buffer\n"); + + return __bpf_object__open("[buffer]", obj_buf, obj_buf_sz); } void bpf_object__close(struct bpf_object *obj) diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index ec3301c..dc966dd 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -26,6 +26,8 @@ void libbpf_set_print(libbpf_print_fn_t warn, struct bpf_object; struct bpf_object *bpf_object__open(const char *path); +struct bpf_object *bpf_object__open_buffer(void *obj_buf, + size_t obj_buf_sz); void bpf_object__close(struct bpf_object *object); #endif -- 1.8.3.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/