[RFC PATCH 12/22] perf bpf: collect bpf programs from object files.

Wang Nan
2015-04-30T11:00:48Z

This patch collects all programs in an object file and links them into
a list for further processing. 'struct bpf_perf_prog' is used 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_perf_prog' to prevent possible
confusion.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
---
tools/perf/util/bpf-loader.c | 91 ++++++++++++++++++++++++++++++++++++++++++++
tools/perf/util/bpf-loader.h | 14 +++++++
2 files changed, 105 insertions(+)

diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index b9c701a..bbebaf1 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -59,11 +59,20 @@ static void bpf_obj_clear_elf(struct bpf_obj *obj)
}
}

+static void bpf_perf_prog_free(struct bpf_perf_prog *prog);
+
static void bpf_obj_close(struct bpf_obj *obj)
{
+ struct bpf_perf_prog *prog, *tmp;
+
if (!obj)
return;

+ list_for_each_entry_safe(prog, tmp, &obj->progs_list, list) {
+ list_del(&prog->list);
+ bpf_perf_prog_free(prog);
+ }
+
bpf_obj_clear_elf(obj);

if (obj->path)
@@ -85,6 +94,7 @@ static struct bpf_obj *bpf_obj_alloc(const char *path)

obj->needs_swap = false;
obj->elf.fd = -1;
+ INIT_LIST_HEAD(&obj->progs_list);
return obj;
out:
bpf_obj_close(obj);
@@ -255,6 +265,70 @@ static int bpf_obj_config_init(struct bpf_obj *obj, void *data,
return 0;
}

+static void
+bpf_perf_prog_free(struct bpf_perf_prog *prog)
+{
+ if (!prog)
+ return;
+
+ if (prog->name)
+ free(prog->name);
+ if (prog->insns)
+ free(prog->insns);
+ free(prog);
+}
+
+static struct bpf_perf_prog *
+bpf_perf_prog_alloc(struct bpf_obj *obj __maybe_unused,
+ void *data, size_t size,
+ char *name, int idx)
+{
+ struct bpf_perf_prog *prog;
+
+ if (size < sizeof(struct bpf_insn)) {
+ pr_err("bpf: corrupted section %s\n", name);
+ return NULL;
+ }
+
+ prog = calloc(1, sizeof(struct bpf_perf_prog));
+ if (!prog) {
+ pr_err("bpf: failed to alloc prog\n");
+ return NULL;
+ }
+
+ /*
+ * Name of a program could be:
+ * "k(ret)probe/[a-zA-Z_][a-zA-Z_0-9]"
+ *
+ * or
+ *
+ * "[a-zA-Z_][a-zA-Z_0-9]"
+ *
+ * Will be parsed in other function. This function only saves
+ * the name.
+ */
+ prog->name = strdup(name);
+ if (!prog->name) {
+ pr_err("bpf: failed to alloc name for prog %s\n",
+ name);
+ goto out;
+ }
+
+ prog->insns = malloc(size);
+ if (!prog->insns) {
+ pr_err("bpf: 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_perf_prog_free(prog);
+ return NULL;
+}
+
static int bpf_obj_elf_collect(struct bpf_obj *obj)
{
Elf *elf = obj->elf.elf;
@@ -322,6 +396,23 @@ static int bpf_obj_elf_collect(struct bpf_obj *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_perf_prog *prog;
+
+ prog = bpf_perf_prog_alloc(obj, data->d_buf,
+ data->d_size, name,
+ idx);
+ if (!prog) {
+ pr_err("bpf: failed to alloc "
+ "program %s (%s)", name, obj->path);
+ err = -ENOMEM;
+ } else {
+ pr_debug("bpf: found program %s\n",
+ prog->name);
+ list_add(&prog->list, &obj->progs_list);
+ }
}
if (err)
goto out;
diff --git a/tools/perf/util/bpf-loader.h b/tools/perf/util/bpf-loader.h
index f0b573c..f9cb46b 100644
--- a/tools/perf/util/bpf-loader.h
+++ b/tools/perf/util/bpf-loader.h
@@ -19,9 +19,23 @@
int bpf__load(const char *path);
int bpf__run(void);

+struct bpf_perf_prog {
+ struct list_head list;
+
+ /* Index in elf obj file, for relocation use. */
+ int idx;
+ char *name;
+ struct bpf_insn *insns;
+ size_t insns_cnt;
+};
+
struct bpf_obj {
/* All bpf objs should be linked together. */
struct list_head list;
+
+ /* All eBPF programs are linked at this list */
+ struct list_head progs_list;
+
char *path;
bool needs_swap;
char license[64];
--
1.8.3.4