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Date: Fri, 15 May 2015 07:51:08 +0000
From: Wang Nan <wangnan0@...wei.com>
To: <paulus@...ba.org>, <a.p.zijlstra@...llo.nl>, <mingo@...hat.com>,
<acme@...nel.org>, <namhyung@...nel.org>, <jolsa@...nel.org>,
<adrian.hunter@...el.com>, <dsahern@...il.com>, <ast@...mgrid.com>,
<daniel@...earbox.net>, <brendan.d.gregg@...il.com>,
<masami.hiramatsu.pt@...achi.com>
CC: <linux-kernel@...r.kernel.org>, <lizefan@...wei.com>,
<pi3orama@....com>, <wangnan0@...wei.com>
Subject: [RFC PATCH v2 15/37] tools lib bpf: collect bpf programs from object files.
This patch collects all programs in an object file into an array of
'struct bpf_program' for further processing. That structure is for
representing each eBPF program. 'bpf_prog' should be a better name, but
it has been used by linux/filter.h. Although it is a kernel space name,
I still prefer to call it 'bpf_program' to prevent possible confusion.
Signed-off-by: Wang Nan <wangnan0@...wei.com>
---
tools/lib/bpf/libbpf.c | 111 +++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 111 insertions(+)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 2068f0b..18b221f 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -77,6 +77,18 @@ void libbpf_set_print(int (*warn)(const char *format, ...),
# define LIBBPF_ELF_C_READ_MMAP ELF_C_READ
#endif
+/*
+ * bpf_prog should be a better name but it has been used in
+ * linux/filter.h.
+ */
+struct bpf_program {
+ /* Index in elf obj file, for relocation use. */
+ int idx;
+ char *section_name;
+ struct bpf_insn *insns;
+ size_t insns_cnt;
+};
+
struct bpf_object {
char *path;
bool needs_swap;
@@ -86,6 +98,9 @@ struct bpf_object {
size_t maps_buf_sz;
char *config_str;
+ struct bpf_program *programs;
+ size_t nr_programs;
+
/*
* Information when doing elf related work. Only valid if fd
* is valid.
@@ -99,6 +114,79 @@ struct bpf_object {
};
#define obj_elf_valid(o) ((o)->elf.fd >= 0)
+static void bpf_clear_program(struct bpf_program *prog)
+{
+ if (!prog)
+ return;
+ if (prog->section_name) {
+ free(prog->section_name);
+ prog->section_name = NULL;
+ }
+ if (prog->insns) {
+ free(prog->insns);
+ prog->insns = NULL;
+ }
+ prog->insns_cnt = 0;
+ prog->idx = -1;
+}
+
+static struct bpf_program *
+bpf_program_alloc(struct bpf_object *obj, void *data, size_t size,
+ char *name, int idx)
+{
+ struct bpf_program *prog, *progs;
+ int nr_progs;
+
+ if (size < sizeof(struct bpf_insn)) {
+ pr_warning("corrupted section '%s'\n", name);
+ return NULL;
+ }
+
+ progs = obj->programs;
+ nr_progs = obj->nr_programs;
+
+ progs = realloc(progs, sizeof(*prog) * (nr_progs + 1));
+ if (!progs) {
+ /*
+ * In this case the original obj->programs
+ * is still valid, so don't need special treat for
+ * bpf_close_object().
+ */
+ pr_warning("failed to alloc a new program '%s'\n",
+ name);
+ return NULL;
+ }
+
+ obj->programs = progs;
+
+ prog = &progs[nr_progs];
+ bzero(prog, sizeof(*prog));
+
+ obj->nr_programs = nr_progs + 1;
+
+ prog->section_name = strdup(name);
+ if (!prog->section_name) {
+ pr_warning("failed to alloc name for prog %s\n",
+ name);
+ goto out;
+ }
+
+ prog->insns = malloc(size);
+ if (!prog->insns) {
+ pr_warning("failed to alloc insns for %s\n", name);
+ goto out;
+ }
+ prog->insns_cnt = size / sizeof(struct bpf_insn);
+ memcpy(prog->insns, data,
+ prog->insns_cnt * sizeof(struct bpf_insn));
+ prog->idx = idx;
+
+ return prog;
+out:
+ bpf_clear_program(prog);
+ return NULL;
+}
+
static struct bpf_object *__bpf_obj_alloc(const char *path)
{
struct bpf_object *obj;
@@ -380,6 +468,22 @@ static int bpf_obj_elf_collect(struct bpf_object *obj)
err = -EEXIST;
} else
obj->elf.symbols = data;
+ } else if ((sh.sh_type == SHT_PROGBITS) &&
+ (sh.sh_flags & SHF_EXECINSTR) &&
+ (data->d_size > 0)) {
+ struct bpf_program *prog;
+
+ prog = bpf_program_alloc(obj, data->d_buf,
+ data->d_size, name,
+ idx);
+ if (!prog) {
+ pr_warning("failed to alloc "
+ "program %s (%s)", name,
+ obj->path);
+ err = -ENOMEM;
+ } else
+ pr_debug("found program %s\n",
+ prog->section_name);
}
if (err)
goto out;
@@ -446,5 +550,12 @@ void bpf_close_object(struct bpf_object *obj)
free(obj->maps_buf);
if (obj->config_str)
free(obj->config_str);
+ if (obj->programs) {
+ size_t i;
+
+ for (i = 0; i < obj->nr_programs; i++)
+ bpf_clear_program(&obj->programs[i]);
+ free(obj->programs);
+ }
free(obj);
}
--
1.8.3.4
--
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