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Groups > linux.kernel > #1179818

[PATCH v11 16/39] bpf tools: Create eBPF maps defined in an object file

From Wang Nan <wangnan0@huawei.com>
Newsgroups linux.kernel
Subject [PATCH v11 16/39] bpf tools: Create eBPF maps defined in an object file
Date 2015-07-08 15:30 +0200
Message-ID <pJXAe-3fG-31@gated-at.bofh.it> (permalink)
References <pJXqx-3bZ-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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This patch creates maps based on 'map' section in object file using
bpf_create_map(), and stores the fds into an array in 'struct
bpf_object'.

Previous patches parse ELF object file and collects required data, but
doesn't play with the kernel. They belong to the 'opening' phase. This
patch is the first patch in 'loading' phase. The 'loaded' field is
introduced in 'struct bpf_object' to avoid loading an object twice,
because the loading phase clears resources collected during the opening
which becomes useless after loading. In this patch, maps_buf is cleared.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David Ahern <dsahern@gmail.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kaixu Xia <xiakaixu@huawei.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1435716878-189507-17-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/lib/bpf/libbpf.c | 102 +++++++++++++++++++++++++++++++++++++++++++++++++
 tools/lib/bpf/libbpf.h |   4 ++
 2 files changed, 106 insertions(+)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 4f13772..c214e1c 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -21,6 +21,7 @@
 #include <gelf.h>
 
 #include "libbpf.h"
+#include "bpf.h"
 
 #define __printf(a, b)	__attribute__((format(printf, a, b)))
 
@@ -105,6 +106,13 @@ struct bpf_object {
 
 	struct bpf_program *programs;
 	size_t nr_programs;
+	int *map_fds;
+	/*
+	 * This field is required because maps_buf will be freed and
+	 * maps_buf_sz will be set to 0 after loaded.
+	 */
+	size_t nr_map_fds;
+	bool loaded;
 
 	/*
 	 * Information when doing elf related work. Only valid if fd
@@ -232,6 +240,7 @@ static struct bpf_object *bpf_object__new(const char *path,
 	obj->efile.obj_buf = obj_buf;
 	obj->efile.obj_buf_sz = obj_buf_sz;
 
+	obj->loaded = false;
 	return obj;
 }
 
@@ -568,6 +577,62 @@ bpf_program__collect_reloc(struct bpf_program *prog,
 	return 0;
 }
 
+static int
+bpf_object__create_maps(struct bpf_object *obj)
+{
+	unsigned int i;
+	size_t nr_maps;
+	int *pfd;
+
+	nr_maps = obj->maps_buf_sz / sizeof(struct bpf_map_def);
+	if (!obj->maps_buf || !nr_maps) {
+		pr_debug("don't need create maps for %s\n",
+			 obj->path);
+		return 0;
+	}
+
+	obj->map_fds = malloc(sizeof(int) * nr_maps);
+	if (!obj->map_fds) {
+		pr_warning("realloc perf_bpf_map_fds failed\n");
+		return -ENOMEM;
+	}
+	obj->nr_map_fds = nr_maps;
+
+	/* fill all fd with -1 */
+	memset(obj->map_fds, 0xff, sizeof(int) * nr_maps);
+
+	pfd = obj->map_fds;
+	for (i = 0; i < nr_maps; i++) {
+		struct bpf_map_def def;
+
+		def = *(struct bpf_map_def *)(obj->maps_buf +
+				i * sizeof(struct bpf_map_def));
+
+		*pfd = bpf_create_map(def.type,
+				      def.key_size,
+				      def.value_size,
+				      def.max_entries);
+		if (*pfd < 0) {
+			size_t j;
+			int err = *pfd;
+
+			pr_warning("failed to create map: %s\n",
+				   strerror(errno));
+			for (j = 0; j < i; j++)
+				zclose(obj->map_fds[j]);
+			obj->nr_map_fds = 0;
+			zfree(&obj->map_fds);
+			return err;
+		}
+		pr_debug("create map: fd=%d\n", *pfd);
+		pfd++;
+	}
+
+	zfree(&obj->maps_buf);
+	obj->maps_buf_sz = 0;
+	return 0;
+}
+
 static int bpf_object__collect_reloc(struct bpf_object *obj)
 {
 	int i, err;
@@ -671,6 +736,42 @@ struct bpf_object *bpf_object__open_buffer(void *obj_buf,
 	return __bpf_object__open("[buffer]", obj_buf, obj_buf_sz);
 }
 
+int bpf_object__unload(struct bpf_object *obj)
+{
+	size_t i;
+
+	if (!obj)
+		return -EINVAL;
+
+	for (i = 0; i < obj->nr_map_fds; i++)
+		zclose(obj->map_fds[i]);
+	zfree(&obj->map_fds);
+	obj->nr_map_fds = 0;
+
+	return 0;
+}
+
+int bpf_object__load(struct bpf_object *obj)
+{
+	if (!obj)
+		return -EINVAL;
+
+	if (obj->loaded) {
+		pr_warning("object should not be loaded twice\n");
+		return -EINVAL;
+	}
+
+	obj->loaded = true;
+	if (bpf_object__create_maps(obj))
+		goto out;
+
+	return 0;
+out:
+	bpf_object__unload(obj);
+	pr_warning("failed to load object '%s'\n", obj->path);
+	return -EINVAL;
+}
+
 void bpf_object__close(struct bpf_object *obj)
 {
 	size_t i;
@@ -679,6 +780,7 @@ void bpf_object__close(struct bpf_object *obj)
 		return;
 
 	bpf_object__elf_finish(obj);
+	bpf_object__unload(obj);
 
 	zfree(&obj->maps_buf);
 
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 6e75acd..3e69600 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -30,6 +30,10 @@ struct bpf_object *bpf_object__open_buffer(void *obj_buf,
 					   size_t obj_buf_sz);
 void bpf_object__close(struct bpf_object *object);
 
+/* Load/unload object into/from kernel */
+int bpf_object__load(struct bpf_object *obj);
+int bpf_object__unload(struct bpf_object *obj);
+
 /*
  * We don't need __attribute__((packed)) now since it is
  * unnecessary for 'bpf_map_def' because they are all aligned.
-- 
1.8.3.4

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Thread

[PATCH v11 00/39] perf tools: filtering events using eBPF programs - part1 Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 03/39] bpf tools: Introduce 'bpf' library and add bpf feature check Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 35/39] perf tools: Add bpf_fd field to evsel and config it Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 28/39] perf tools: Make perf depend on libbpf Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 34/39] perf record: Load all eBPF object into kernel Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 13/39] bpf tools: Collect relocation sections from SHT_REL sections Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 22/39] bpf tools: Link all bpf objects onto a list Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 02/39] tracing, perf: Implement BPF programs attached to uprobes Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 07/39] bpf tools: Check endianness and make libbpf fail early Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 38/39] perf record: Add clang options for compiling BPF scripts Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 33/39] perf record: Probe at kprobe points Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 32/39] perf probe: Attach trace_probe_event with perf_probe_event Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 36/39] perf tools: Attach eBPF program to perf event Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 23/39] perf tools: Introduce llvm config options Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 11/39] bpf tools: Collect symbol table from SHT_SYMTAB section Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 10/39] bpf tools: Collect map definitions from 'maps' section Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 19/39] bpf tools: Load eBPF programs in object files into kernel Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 18/39] bpf tools: Introduce bpf_load_program() to bpf.c Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 15/39] bpf tools: Add bpf.c/h for common bpf operations Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 29/39] perf record: Enable passing bpf object file to --event Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 05/39] bpf tools: Open eBPF object file and do basic validation Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 27/39] perf tests: Add LLVM test for eBPF on-the-fly compiling Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 09/39] bpf tools: Collect version and license from ELF sections Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 31/39] perf tools: Parse probe points of eBPF programs during preparation Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 17/39] bpf tools: Relocate eBPF programs Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 16/39] bpf tools: Create eBPF maps defined in an object file Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 14/39] bpf tools: Record map accessing instructions for each program Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 25/39] perf tools: Auto detecting kernel build directory Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 39/39] bpf tools: Load a program with different instance using preprocessor Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 04/39] bpf tools: Allow caller to set printing function Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 21/39] bpf tools: Introduce accessors for struct bpf_object Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 06/39] bpf tools: Read eBPF object from buffer Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 24/39] perf tools: Call clang to compile C source to object code Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 20/39] bpf tools: Introduce accessors for struct bpf_program Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 37/39] perf tools: Suppress probing messages when probing by BPF loading Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 26/39] perf tools: Auto detecting kernel include options Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  Re: [PATCH v11 00/39] perf tools: filtering events using eBPF  programs - part1 Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-07-08 16:10 +0200

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