From: Alexei Starovoitov <ast@xxxxxxxxxx>
Add support for FD_IDX and make libbpf prefer that approach to loading programs
to make testing and bisection easy.
The next patch will fine tune libbpf behavior to use FEAT_FD_IDX only when
generating loader program.
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
---
tools/lib/bpf/bpf.c | 1 +
tools/lib/bpf/libbpf.c | 73 +++++++++++++++++++++++++++++----
tools/lib/bpf/libbpf_internal.h | 1 +
3 files changed, 68 insertions(+), 7 deletions(-)
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index bba48ff4c5c0..b96a3aba6fcc 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -252,6 +252,7 @@ int libbpf__bpf_prog_load(const struct bpf_prog_load_params *load_attr)
attr.prog_btf_fd = load_attr->prog_btf_fd;
attr.prog_flags = load_attr->prog_flags;
+ attr.fd_array = ptr_to_u64(load_attr->fd_array);
attr.func_info_rec_size = load_attr->func_info_rec_size;
attr.func_info_cnt = load_attr->func_info_cnt;
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 491349a31a06..0b9270403a77 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -175,6 +175,8 @@ enum kern_feature_id {
FEAT_MODULE_BTF,
/* BTF_KIND_FLOAT support */
FEAT_BTF_FLOAT,
+ /* Kernel support for FD_IDX */
+ FEAT_FD_IDX,
__FEAT_CNT,
};
@@ -288,6 +290,7 @@ struct bpf_program {
__u32 line_info_rec_size;
__u32 line_info_cnt;
__u32 prog_flags;
+ int *fd_array;
};
struct bpf_struct_ops {
@@ -4238,6 +4241,29 @@ static int probe_module_btf(void)
return !err;
}
+static int probe_kern_fd_idx(void)
+{
+ struct bpf_load_program_attr attr;
+ struct bpf_insn insns[] = {
+ BPF_LD_IMM64_RAW(BPF_REG_0, BPF_PSEUDO_MAP_IDX, 0),
+ BPF_EXIT_INSN(),
+ };
+ int err;
+
+ memset(&attr, 0, sizeof(attr));
+ attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
+ attr.insns = insns;
+ attr.insns_cnt = ARRAY_SIZE(insns);
+ attr.license = "GPL";
+
+ err = bpf_load_program_xattr(&attr, NULL, 0);
+ if (err >= 0) {
+ close(err);
+ return 0;
+ }
+ return errno == EPROTO;
+}
+
enum kern_feature_result {
FEAT_UNKNOWN = 0,
FEAT_SUPPORTED = 1,
@@ -4288,6 +4314,9 @@ static struct kern_feature_desc {
[FEAT_BTF_FLOAT] = {
"BTF_KIND_FLOAT support", probe_kern_btf_float,
},
+ [FEAT_FD_IDX] = {
+ "prog_load with fd_idx", probe_kern_fd_idx,
+ },
};
static bool kernel_supports(enum kern_feature_id feat_id)
@@ -6368,19 +6397,34 @@ bpf_object__relocate_data(struct bpf_object *obj, struct bpf_program *prog)
switch (relo->type) {
case RELO_LD64:
- insn[0].src_reg = BPF_PSEUDO_MAP_FD;
- insn[0].imm = obj->maps[relo->map_idx].fd;
+ if (kernel_supports(FEAT_FD_IDX)) {
+ insn[0].src_reg = BPF_PSEUDO_MAP_IDX;
+ insn[0].imm = relo->map_idx;
+ } else {
+ insn[0].src_reg = BPF_PSEUDO_MAP_FD;
+ insn[0].imm = obj->maps[relo->map_idx].fd;
+ }
break;
case RELO_DATA:
- insn[0].src_reg = BPF_PSEUDO_MAP_VALUE;
insn[1].imm = insn[0].imm + relo->sym_off;
- insn[0].imm = obj->maps[relo->map_idx].fd;
+ if (kernel_supports(FEAT_FD_IDX)) {
+ insn[0].src_reg = BPF_PSEUDO_MAP_IDX_VALUE;
+ insn[0].imm = relo->map_idx;
+ } else {
+ insn[0].src_reg = BPF_PSEUDO_MAP_VALUE;
+ insn[0].imm = obj->maps[relo->map_idx].fd;
+ }
break;
case RELO_EXTERN_VAR:
ext = &obj->externs[relo->sym_off];
if (ext->type == EXT_KCFG) {
- insn[0].src_reg = BPF_PSEUDO_MAP_VALUE;
- insn[0].imm = obj->maps[obj->kconfig_map_idx].fd;
+ if (kernel_supports(FEAT_FD_IDX)) {
+ insn[0].src_reg = BPF_PSEUDO_MAP_IDX_VALUE;
+ insn[0].imm = obj->kconfig_map_idx;
+ } else {
+ insn[0].src_reg = BPF_PSEUDO_MAP_VALUE;
+ insn[0].imm = obj->maps[obj->kconfig_map_idx].fd;
+ }
insn[1].imm = ext->kcfg.data_off;
} else /* EXT_KSYM */ {
if (ext->ksym.type_id) { /* typed ksyms */
@@ -7106,6 +7150,7 @@ 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);
@@ -7296,6 +7341,7 @@ 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;
@@ -7306,6 +7352,14 @@ bpf_object__load_progs(struct bpf_object *obj, int log_level)
return err;
}
+ if (kernel_supports(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))
@@ -7315,10 +7369,15 @@ 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);
- if (err)
+ prog->fd_array = NULL;
+ if (err) {
+ free(fd_array);
return err;
+ }
}
+ free(fd_array);
return 0;
}
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index ee426226928f..2d4f4a995f35 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -249,6 +249,7 @@ struct bpf_prog_load_params {
__u32 log_level;
char *log_buf;
size_t log_buf_sz;
+ int *fd_array;
};
int libbpf__bpf_prog_load(const struct bpf_prog_load_params *load_attr);
--
2.30.2
