tools/bpf: bpftool: add support for func types

This patch added support to print function signature
if btf func_info is available. Note that ksym
now uses function name instead of prog_name as
prog_name has a limit of 16 bytes including
ending '\0'.

The following is a sample output for selftests
test_btf with file test_btf_haskv.o for translated insns
and jited insns respectively.

  $ bpftool prog dump xlated id 1
  int _dummy_tracepoint(struct dummy_tracepoint_args * arg):
     0: (85) call pc+2#bpf_prog_2dcecc18072623fc_test_long_fname_1
     1: (b7) r0 = 0
     2: (95) exit
  int test_long_fname_1(struct dummy_tracepoint_args * arg):
     3: (85) call pc+1#bpf_prog_89d64e4abf0f0126_test_long_fname_2
     4: (95) exit
  int test_long_fname_2(struct dummy_tracepoint_args * arg):
     5: (b7) r2 = 0
     6: (63) *(u32 *)(r10 -4) = r2
     7: (79) r1 = *(u64 *)(r1 +8)
     ...
     22: (07) r1 += 1
     23: (63) *(u32 *)(r0 +4) = r1
     24: (95) exit

  $ bpftool prog dump jited id 1
  int _dummy_tracepoint(struct dummy_tracepoint_args * arg):
  bpf_prog_b07ccb89267cf242__dummy_tracepoint:
     0:   push   %rbp
     1:   mov    %rsp,%rbp
    ......
    3c:   add    $0x28,%rbp
    40:   leaveq
    41:   retq

  int test_long_fname_1(struct dummy_tracepoint_args * arg):
  bpf_prog_2dcecc18072623fc_test_long_fname_1:
     0:   push   %rbp
     1:   mov    %rsp,%rbp
    ......
    3a:   add    $0x28,%rbp
    3e:   leaveq
    3f:   retq

  int test_long_fname_2(struct dummy_tracepoint_args * arg):
  bpf_prog_89d64e4abf0f0126_test_long_fname_2:
     0:   push   %rbp
     1:   mov    %rsp,%rbp
    ......
    80:   add    $0x28,%rbp
    84:   leaveq
    85:   retq

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

tools/bpf/bpftool/btf_dumper.c

@@ -249,3 +249,139 @@ int btf_dumper_type(const struct btf_dumper *d, __u32 type_id,
 {
 	return btf_dumper_do_type(d, type_id, 0, data);
 }
+
+#define BTF_PRINT_ARG(...)						\
+	do {								\
+		pos += snprintf(func_sig + pos, size - pos,		\
+				__VA_ARGS__);				\
+		if (pos >= size)					\
+			return -1;					\
+	} while (0)
+#define BTF_PRINT_TYPE(type)					\
+	do {								\
+		pos = __btf_dumper_type_only(btf, type, func_sig,	\
+					     pos, size);		\
+		if (pos == -1)						\
+			return -1;					\
+	} while (0)
+
+static int btf_dump_func(const struct btf *btf, char *func_sig,
+			 const struct btf_type *func_proto,
+			 const struct btf_type *func, int pos, int size);
+
+static int __btf_dumper_type_only(const struct btf *btf, __u32 type_id,
+				  char *func_sig, int pos, int size)
+{
+	const struct btf_type *proto_type;
+	const struct btf_array *array;
+	const struct btf_type *t;
+
+	if (!type_id) {
+		BTF_PRINT_ARG("void ");
+		return pos;
+	}
+
+	t = btf__type_by_id(btf, type_id);
+
+	switch (BTF_INFO_KIND(t->info)) {
+	case BTF_KIND_INT:
+		BTF_PRINT_ARG("%s ", btf__name_by_offset(btf, t->name_off));
+		break;
+	case BTF_KIND_STRUCT:
+		BTF_PRINT_ARG("struct %s ",
+			      btf__name_by_offset(btf, t->name_off));
+		break;
+	case BTF_KIND_UNION:
+		BTF_PRINT_ARG("union %s ",
+			      btf__name_by_offset(btf, t->name_off));
+		break;
+	case BTF_KIND_ENUM:
+		BTF_PRINT_ARG("enum %s ",
+			      btf__name_by_offset(btf, t->name_off));
+		break;
+	case BTF_KIND_ARRAY:
+		array = (struct btf_array *)(t + 1);
+		BTF_PRINT_TYPE(array->type);
+		BTF_PRINT_ARG("[%d]", array->nelems);
+		break;
+	case BTF_KIND_PTR:
+		BTF_PRINT_TYPE(t->type);
+		BTF_PRINT_ARG("* ");
+		break;
+	case BTF_KIND_UNKN:
+	case BTF_KIND_FWD:
+	case BTF_KIND_TYPEDEF:
+		return -1;
+	case BTF_KIND_VOLATILE:
+		BTF_PRINT_ARG("volatile ");
+		BTF_PRINT_TYPE(t->type);
+		break;
+	case BTF_KIND_CONST:
+		BTF_PRINT_ARG("const ");
+		BTF_PRINT_TYPE(t->type);
+		break;
+	case BTF_KIND_RESTRICT:
+		BTF_PRINT_ARG("restrict ");
+		BTF_PRINT_TYPE(t->type);
+		break;
+	case BTF_KIND_FUNC_PROTO:
+		pos = btf_dump_func(btf, func_sig, t, NULL, pos, size);
+		if (pos == -1)
+			return -1;
+		break;
+	case BTF_KIND_FUNC:
+		proto_type = btf__type_by_id(btf, t->type);
+		pos = btf_dump_func(btf, func_sig, proto_type, t, pos, size);
+		if (pos == -1)
+			return -1;
+		break;
+	default:
+		return -1;
+	}
+
+	return pos;
+}
+
+static int btf_dump_func(const struct btf *btf, char *func_sig,
+			 const struct btf_type *func_proto,
+			 const struct btf_type *func, int pos, int size)
+{
+	int i, vlen;
+
+	BTF_PRINT_TYPE(func_proto->type);
+	if (func)
+		BTF_PRINT_ARG("%s(", btf__name_by_offset(btf, func->name_off));
+	else
+		BTF_PRINT_ARG("(");
+	vlen = BTF_INFO_VLEN(func_proto->info);
+	for (i = 0; i < vlen; i++) {
+		struct btf_param *arg = &((struct btf_param *)(func_proto + 1))[i];
+
+		if (i)
+			BTF_PRINT_ARG(", ");
+		if (arg->type) {
+			BTF_PRINT_TYPE(arg->type);
+			BTF_PRINT_ARG("%s",
+				      btf__name_by_offset(btf, arg->name_off));
+		} else {
+			BTF_PRINT_ARG("...");
+		}
+	}
+	BTF_PRINT_ARG(")");
+
+	return pos;
+}
+
+void btf_dumper_type_only(const struct btf *btf, __u32 type_id, char *func_sig,
+			  int size)
+{
+	int err;
+
+	func_sig[0] = '\0';
+	if (!btf)
+		return;
+
+	err = __btf_dumper_type_only(btf, type_id, func_sig, 0, size);
+	if (err < 0)
+		func_sig[0] = '\0';
+}

tools/bpf/bpftool/main.h

@@ -187,6 +187,8 @@ struct btf_dumper {
  */
 int btf_dumper_type(const struct btf_dumper *d, __u32 type_id,
 		    const void *data);
+void btf_dumper_type_only(const struct btf *btf, __u32 func_type_id,
+			  char *func_only, int size);
 
 struct nlattr;
 struct ifinfomsg;

tools/bpf/bpftool/prog.c

@@ -47,6 +47,7 @@
 #include <linux/err.h>
 
 #include <bpf.h>
+#include <btf.h>
 #include <libbpf.h>
 
 #include "cfg.h"
@@ -451,14 +452,19 @@ static int do_dump(int argc, char **argv)
 	struct bpf_prog_info info = {};
 	unsigned int *func_lens = NULL;
 	const char *disasm_opt = NULL;
+	unsigned int finfo_rec_size;
 	unsigned int nr_func_ksyms;
 	unsigned int nr_func_lens;
 	struct dump_data dd = {};
 	__u32 len = sizeof(info);
+	struct btf *btf = NULL;
+	void *func_info = NULL;
+	unsigned int finfo_cnt;
 	unsigned int buf_size;
 	char *filepath = NULL;
 	bool opcodes = false;
 	bool visual = false;
+	char func_sig[1024];
 	unsigned char *buf;
 	__u32 *member_len;
 	__u64 *member_ptr;
@@ -551,6 +557,17 @@ static int do_dump(int argc, char **argv)
 		}
 	}
 
+	finfo_cnt = info.func_info_cnt;
+	finfo_rec_size = info.func_info_rec_size;
+	if (finfo_cnt && finfo_rec_size) {
+		func_info = malloc(finfo_cnt * finfo_rec_size);
+		if (!func_info) {
+			p_err("mem alloc failed");
+			close(fd);
+			goto err_free;
+		}
+	}
+
 	memset(&info, 0, sizeof(info));
 
 	*member_ptr = ptr_to_u64(buf);
@@ -559,6 +576,9 @@ static int do_dump(int argc, char **argv)
 	info.nr_jited_ksyms = nr_func_ksyms;
 	info.jited_func_lens = ptr_to_u64(func_lens);
 	info.nr_jited_func_lens = nr_func_lens;
+	info.func_info_cnt = finfo_cnt;
+	info.func_info_rec_size = finfo_rec_size;
+	info.func_info = ptr_to_u64(func_info);
 
 	err = bpf_obj_get_info_by_fd(fd, &info, &len);
 	close(fd);
@@ -582,6 +602,18 @@ static int do_dump(int argc, char **argv)
 		goto err_free;
 	}
 
+	if (info.func_info_cnt != finfo_cnt) {
+		p_err("incorrect func_info_cnt %d vs. expected %d",
+		      info.func_info_cnt, finfo_cnt);
+		goto err_free;
+	}
+
+	if (info.func_info_rec_size != finfo_rec_size) {
+		p_err("incorrect func_info_rec_size %d vs. expected %d",
+		      info.func_info_rec_size, finfo_rec_size);
+		goto err_free;
+	}
+
 	if ((member_len == &info.jited_prog_len &&
 	     info.jited_prog_insns == 0) ||
 	    (member_len == &info.xlated_prog_len &&
@@ -590,6 +622,11 @@ static int do_dump(int argc, char **argv)
 		goto err_free;
 	}
 
+	if (info.btf_id && btf_get_from_id(info.btf_id, &btf)) {
+		p_err("failed to get btf");
+		goto err_free;
+	}
+
 	if (filepath) {
 		fd = open(filepath, O_WRONLY | O_CREAT | O_TRUNC, 0600);
 		if (fd < 0) {
@@ -622,6 +659,7 @@ static int do_dump(int argc, char **argv)
 
 		if (info.nr_jited_func_lens && info.jited_func_lens) {
 			struct kernel_sym *sym = NULL;
+			struct bpf_func_info *record;
 			char sym_name[SYM_MAX_NAME];
 			unsigned char *img = buf;
 			__u64 *ksyms = NULL;
@@ -648,12 +686,25 @@ static int do_dump(int argc, char **argv)
 					strcpy(sym_name, "unknown");
 				}
 
+				if (func_info) {
+					record = func_info + i * finfo_rec_size;
+					btf_dumper_type_only(btf, record->type_id,
+							     func_sig,
+							     sizeof(func_sig));
+				}
+
 				if (json_output) {
 					jsonw_start_object(json_wtr);
+					if (func_info && func_sig[0] != '\0') {
+						jsonw_name(json_wtr, "proto");
+						jsonw_string(json_wtr, func_sig);
+					}
 					jsonw_name(json_wtr, "name");
 					jsonw_string(json_wtr, sym_name);
 					jsonw_name(json_wtr, "insns");
 				} else {
+					if (func_info && func_sig[0] != '\0')
+						printf("%s:\n", func_sig);
 					printf("%s:\n", sym_name);
 				}
 
@@ -682,6 +733,9 @@ static int do_dump(int argc, char **argv)
 		kernel_syms_load(&dd);
 		dd.nr_jited_ksyms = info.nr_jited_ksyms;
 		dd.jited_ksyms = (__u64 *) info.jited_ksyms;
+		dd.btf = btf;
+		dd.func_info = func_info;
+		dd.finfo_rec_size = finfo_rec_size;
 
 		if (json_output)
 			dump_xlated_json(&dd, buf, *member_len, opcodes);
@@ -693,12 +747,14 @@ static int do_dump(int argc, char **argv)
 	free(buf);
 	free(func_ksyms);
 	free(func_lens);
+	free(func_info);
 	return 0;
 
 err_free:
 	free(buf);
 	free(func_ksyms);
 	free(func_lens);
+	free(func_info);
 	return -1;
 }
 

tools/bpf/bpftool/xlated_dumper.c

@@ -242,11 +242,15 @@ void dump_xlated_json(struct dump_data *dd, void *buf, unsigned int len,
 		.cb_imm		= print_imm,
 		.private_data	= dd,
 	};
+	struct bpf_func_info *record;
 	struct bpf_insn *insn = buf;
+	struct btf *btf = dd->btf;
 	bool double_insn = false;
+	char func_sig[1024];
 	unsigned int i;
 
 	jsonw_start_array(json_wtr);
+	record = dd->func_info;
 	for (i = 0; i < len / sizeof(*insn); i++) {
 		if (double_insn) {
 			double_insn = false;
@@ -255,6 +259,20 @@ void dump_xlated_json(struct dump_data *dd, void *buf, unsigned int len,
 		double_insn = insn[i].code == (BPF_LD | BPF_IMM | BPF_DW);
 
 		jsonw_start_object(json_wtr);
+
+		if (btf && record) {
+			if (record->insn_offset == i) {
+				btf_dumper_type_only(btf, record->type_id,
+						     func_sig,
+						     sizeof(func_sig));
+				if (func_sig[0] != '\0') {
+					jsonw_name(json_wtr, "proto");
+					jsonw_string(json_wtr, func_sig);
+				}
+				record = (void *)record + dd->finfo_rec_size;
+			}
+		}
+
 		jsonw_name(json_wtr, "disasm");
 		print_bpf_insn(&cbs, insn + i, true);
 
@@ -297,16 +315,31 @@ void dump_xlated_plain(struct dump_data *dd, void *buf, unsigned int len,
 		.cb_imm		= print_imm,
 		.private_data	= dd,
 	};
+	struct bpf_func_info *record;
 	struct bpf_insn *insn = buf;
+	struct btf *btf = dd->btf;
 	bool double_insn = false;
+	char func_sig[1024];
 	unsigned int i;
 
+	record = dd->func_info;
 	for (i = 0; i < len / sizeof(*insn); i++) {
 		if (double_insn) {
 			double_insn = false;
 			continue;
 		}
 
+		if (btf && record) {
+			if (record->insn_offset == i) {
+				btf_dumper_type_only(btf, record->type_id,
+						     func_sig,
+						     sizeof(func_sig));
+				if (func_sig[0] != '\0')
+					printf("%s:\n", func_sig);
+				record = (void *)record + dd->finfo_rec_size;
+			}
+		}
+
 		double_insn = insn[i].code == (BPF_LD | BPF_IMM | BPF_DW);
 
 		printf("% 4d: ", i);

tools/bpf/bpftool/xlated_dumper.h

@@ -51,6 +51,9 @@ struct dump_data {
 	__u32 sym_count;
 	__u64 *jited_ksyms;
 	__u32 nr_jited_ksyms;
+	struct btf *btf;
+	void *func_info;
+	__u32 finfo_rec_size;
 	char scratch_buff[SYM_MAX_NAME + 8];
 };