[PATCH v4 bpf-next 15/22] libbpf: Use fd_array only with gen_loader.

From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: davem@davemloft.net
Cc: daniel@iogearbox.net, andrii@kernel.org,
	john.fastabend@gmail.com, bpf@vger.kernel.org,
	kernel-team@fb.com
Subject: [PATCH v4 bpf-next 15/22] libbpf: Use fd_array only with gen_loader.
Date: Fri,  7 May 2021 20:48:30 -0700	[thread overview]
Message-ID: <20210508034837.64585-16-alexei.starovoitov@gmail.com> (raw)
In-Reply-To: <20210508034837.64585-1-alexei.starovoitov@gmail.com>

From: Alexei Starovoitov <ast@kernel.org>

Rely on fd_array kernel feature only to generate loader program,
since it's mandatory for it.
Avoid using fd_array by default to preserve test coverage
for old style map_fd patching.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
 tools/lib/bpf/libbpf.c | 24 ++++--------------------
 1 file changed, 4 insertions(+), 20 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 0ca79712f850..24a659448782 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -291,7 +291,6 @@ struct bpf_program {
 	__u32 line_info_rec_size;
 	__u32 line_info_cnt;
 	__u32 prog_flags;
-	int *fd_array;
 };
 
 struct bpf_struct_ops {
@@ -6451,7 +6450,7 @@ bpf_object__relocate_data(struct bpf_object *obj, struct bpf_program *prog)
 
 		switch (relo->type) {
 		case RELO_LD64:
-			if (kernel_supports(obj, FEAT_FD_IDX)) {
+			if (obj->gen_loader) {
 				insn[0].src_reg = BPF_PSEUDO_MAP_IDX;
 				insn[0].imm = relo->map_idx;
 			} else {
@@ -6461,7 +6460,7 @@ bpf_object__relocate_data(struct bpf_object *obj, struct bpf_program *prog)
 			break;
 		case RELO_DATA:
 			insn[1].imm = insn[0].imm + relo->sym_off;
-			if (kernel_supports(obj, FEAT_FD_IDX)) {
+			if (obj->gen_loader) {
 				insn[0].src_reg = BPF_PSEUDO_MAP_IDX_VALUE;
 				insn[0].imm = relo->map_idx;
 			} else {
@@ -6472,7 +6471,7 @@ bpf_object__relocate_data(struct bpf_object *obj, struct bpf_program *prog)
 		case RELO_EXTERN_VAR:
 			ext = &obj->externs[relo->sym_off];
 			if (ext->type == EXT_KCFG) {
-				if (kernel_supports(obj, FEAT_FD_IDX)) {
+				if (obj->gen_loader) {
 					insn[0].src_reg = BPF_PSEUDO_MAP_IDX_VALUE;
 					insn[0].imm = obj->kconfig_map_idx;
 				} else {
@@ -7275,7 +7274,6 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
 	load_attr.attach_btf_id = prog->attach_btf_id;
 	load_attr.kern_version = kern_version;
 	load_attr.prog_ifindex = prog->prog_ifindex;
-	load_attr.fd_array = prog->fd_array;
 
 	/* specify func_info/line_info only if kernel supports them */
 	btf_fd = bpf_object__btf_fd(prog->obj);
@@ -7506,7 +7504,6 @@ static int
 bpf_object__load_progs(struct bpf_object *obj, int log_level)
 {
 	struct bpf_program *prog;
-	int *fd_array = NULL;
 	size_t i;
 	int err;
 
@@ -7517,14 +7514,6 @@ bpf_object__load_progs(struct bpf_object *obj, int log_level)
 			return err;
 	}
 
-	if (kernel_supports(obj, FEAT_FD_IDX) && obj->nr_maps) {
-		fd_array = malloc(sizeof(int) * obj->nr_maps);
-		if (!fd_array)
-			return -ENOMEM;
-		for (i = 0; i < obj->nr_maps; i++)
-			fd_array[i] = obj->maps[i].fd;
-	}
-
 	for (i = 0; i < obj->nr_programs; i++) {
 		prog = &obj->programs[i];
 		if (prog_is_subprog(obj, prog))
@@ -7534,17 +7523,12 @@ bpf_object__load_progs(struct bpf_object *obj, int log_level)
 			continue;
 		}
 		prog->log_level |= log_level;
-		prog->fd_array = fd_array;
 		err = bpf_program__load(prog, obj->license, obj->kern_version);
-		prog->fd_array = NULL;
-		if (err) {
-			free(fd_array);
+		if (err)
 			return err;
-		}
 	}
 	if (obj->gen_loader)
 		bpf_object__free_relocs(obj);
-	free(fd_array);
 	return 0;
 }
 
-- 
2.30.2

