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

[Wang Nan]

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@xxxxxxxxxx>
---
 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

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