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libbpf: Factor out low-level BPF program loading helper

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Refactor low-level API for BPF program loading to not rely on public API
types. This allows painless extension without constant efforts to cleverly not
break backwards compatibility.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20201203204634.1325171-12-andrii@kernel.org
This commit is contained in:
Andrii Nakryiko 2020-12-03 12:46:31 -08:00 committed by Alexei Starovoitov
parent 290248a5b7
commit 6aef10a481
3 changed files with 113 additions and 50 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

100
tools/lib/bpf/bpf.c
View File

@ -215,59 +215,52 @@ alloc_zero_tailing_info(const void *orecord, __u32 cnt,
return info;
}
int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
char *log_buf, size_t log_buf_sz)
int libbpf__bpf_prog_load(const struct bpf_prog_load_params *load_attr)
{
void *finfo = NULL, *linfo = NULL;
union bpf_attr attr;
__u32 log_level;
int fd;
if (!load_attr || !log_buf != !log_buf_sz)
if (!load_attr->log_buf != !load_attr->log_buf_sz)
return -EINVAL;
log_level = load_attr->log_level;
if (log_level > (4 | 2 | 1) || (log_level && !log_buf))
if (load_attr->log_level > (4 | 2 | 1) || (load_attr->log_level && !load_attr->log_buf))
return -EINVAL;
memset(&attr, 0, sizeof(attr));
attr.prog_type = load_attr->prog_type;
attr.expected_attach_type = load_attr->expected_attach_type;
if (attr.prog_type == BPF_PROG_TYPE_STRUCT_OPS ||
attr.prog_type == BPF_PROG_TYPE_LSM) {
attr.attach_btf_id = load_attr->attach_btf_id;
} else if (attr.prog_type == BPF_PROG_TYPE_TRACING ||
attr.prog_type == BPF_PROG_TYPE_EXT) {
attr.attach_btf_id = load_attr->attach_btf_id;
attr.attach_prog_fd = load_attr->attach_prog_fd;
} else {
attr.prog_ifindex = load_attr->prog_ifindex;
attr.kern_version = load_attr->kern_version;
}
attr.insn_cnt = (__u32)load_attr->insns_cnt;
attr.attach_btf_id = load_attr->attach_btf_id;
attr.attach_prog_fd = load_attr->attach_prog_fd;
attr.prog_ifindex = load_attr->prog_ifindex;
attr.kern_version = load_attr->kern_version;
attr.insn_cnt = (__u32)load_attr->insn_cnt;
attr.insns = ptr_to_u64(load_attr->insns);
attr.license = ptr_to_u64(load_attr->license);
attr.log_level = log_level;
if (log_level) {
attr.log_buf = ptr_to_u64(log_buf);
attr.log_size = log_buf_sz;
} else {
attr.log_buf = ptr_to_u64(NULL);
attr.log_size = 0;
attr.log_level = load_attr->log_level;
if (attr.log_level) {
attr.log_buf = ptr_to_u64(load_attr->log_buf);
attr.log_size = load_attr->log_buf_sz;
}
attr.prog_btf_fd = load_attr->prog_btf_fd;
attr.prog_flags = load_attr->prog_flags;
attr.func_info_rec_size = load_attr->func_info_rec_size;
attr.func_info_cnt = load_attr->func_info_cnt;
attr.func_info = ptr_to_u64(load_attr->func_info);
attr.line_info_rec_size = load_attr->line_info_rec_size;
attr.line_info_cnt = load_attr->line_info_cnt;
attr.line_info = ptr_to_u64(load_attr->line_info);
if (load_attr->name)
memcpy(attr.prog_name, load_attr->name,
min(strlen(load_attr->name), BPF_OBJ_NAME_LEN - 1));
attr.prog_flags = load_attr->prog_flags;
min(strlen(load_attr->name), (size_t)BPF_OBJ_NAME_LEN - 1));
fd = sys_bpf_prog_load(&attr, sizeof(attr));
if (fd >= 0)
@ -307,19 +300,19 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
}
fd = sys_bpf_prog_load(&attr, sizeof(attr));
if (fd >= 0)
goto done;
}
if (log_level || !log_buf)
if (load_attr->log_level || !load_attr->log_buf)
goto done;
/* Try again with log */
attr.log_buf = ptr_to_u64(log_buf);
attr.log_size = log_buf_sz;
attr.log_buf = ptr_to_u64(load_attr->log_buf);
attr.log_size = load_attr->log_buf_sz;
attr.log_level = 1;
log_buf[0] = 0;
load_attr->log_buf[0] = 0;
fd = sys_bpf_prog_load(&attr, sizeof(attr));
done:
free(finfo);
@ -327,6 +320,49 @@ done:
return fd;
}
int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
char *log_buf, size_t log_buf_sz)
{
struct bpf_prog_load_params p = {};
if (!load_attr || !log_buf != !log_buf_sz)
return -EINVAL;
p.prog_type = load_attr->prog_type;
p.expected_attach_type = load_attr->expected_attach_type;
switch (p.prog_type) {
case BPF_PROG_TYPE_STRUCT_OPS:
case BPF_PROG_TYPE_LSM:
p.attach_btf_id = load_attr->attach_btf_id;
break;
case BPF_PROG_TYPE_TRACING:
case BPF_PROG_TYPE_EXT:
p.attach_btf_id = load_attr->attach_btf_id;
p.attach_prog_fd = load_attr->attach_prog_fd;
break;
default:
p.prog_ifindex = load_attr->prog_ifindex;
p.kern_version = load_attr->kern_version;
}
p.insn_cnt = load_attr->insns_cnt;
p.insns = load_attr->insns;
p.license = load_attr->license;
p.log_level = load_attr->log_level;
p.log_buf = log_buf;
p.log_buf_sz = log_buf_sz;
p.prog_btf_fd = load_attr->prog_btf_fd;
p.func_info_rec_size = load_attr->func_info_rec_size;
p.func_info_cnt = load_attr->func_info_cnt;
p.func_info = load_attr->func_info;
p.line_info_rec_size = load_attr->line_info_rec_size;
p.line_info_cnt = load_attr->line_info_cnt;
p.line_info = load_attr->line_info;
p.name = load_attr->name;
p.prog_flags = load_attr->prog_flags;
return libbpf__bpf_prog_load(&p);
}
int bpf_load_program(enum bpf_prog_type type, const struct bpf_insn *insns,
size_t insns_cnt, const char *license,
__u32 kern_version, char *log_buf,

34
tools/lib/bpf/libbpf.c
View File

@ -6809,7 +6809,7 @@ static int
load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
char *license, __u32 kern_version, int *pfd)
{
struct bpf_load_program_attr load_attr;
struct bpf_prog_load_params load_attr = {};
char *cp, errmsg[STRERR_BUFSIZE];
size_t log_buf_size = 0;
char *log_buf = NULL;
@ -6828,7 +6828,6 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
if (!insns || !insns_cnt)
return -EINVAL;
memset(&load_attr, 0, sizeof(struct bpf_load_program_attr));
load_attr.prog_type = prog->type;
/* old kernels might not support specifying expected_attach_type */
if (!kernel_supports(FEAT_EXP_ATTACH_TYPE) && prog->sec_def &&
@ -6839,19 +6838,14 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
if (kernel_supports(FEAT_PROG_NAME))
load_attr.name = prog->name;
load_attr.insns = insns;
load_attr.insns_cnt = insns_cnt;
load_attr.insn_cnt = insns_cnt;
load_attr.license = license;
if (prog->type == BPF_PROG_TYPE_STRUCT_OPS ||
prog->type == BPF_PROG_TYPE_LSM) {
load_attr.attach_btf_id = prog->attach_btf_id;
} else if (prog->type == BPF_PROG_TYPE_TRACING ||
prog->type == BPF_PROG_TYPE_EXT) {
load_attr.attach_prog_fd = prog->attach_prog_fd;
load_attr.attach_btf_id = prog->attach_btf_id;
} else {
load_attr.kern_version = kern_version;
load_attr.prog_ifindex = prog->prog_ifindex;
}
load_attr.attach_btf_id = prog->attach_btf_id;
load_attr.attach_prog_fd = prog->attach_prog_fd;
load_attr.attach_btf_id = prog->attach_btf_id;
load_attr.kern_version = kern_version;
load_attr.prog_ifindex = prog->prog_ifindex;
/* specify func_info/line_info only if kernel supports them */
btf_fd = bpf_object__btf_fd(prog->obj);
if (btf_fd >= 0 && kernel_supports(FEAT_BTF_FUNC)) {
@ -6875,7 +6869,9 @@ retry_load:
*log_buf = 0;
}
ret = bpf_load_program_xattr(&load_attr, log_buf, log_buf_size);
load_attr.log_buf = log_buf;
load_attr.log_buf_sz = log_buf_size;
ret = libbpf__bpf_prog_load(&load_attr);
if (ret >= 0) {
if (log_buf && load_attr.log_level)
@ -6916,9 +6912,9 @@ retry_load:
pr_warn("-- BEGIN DUMP LOG ---\n");
pr_warn("\n%s\n", log_buf);
pr_warn("-- END LOG --\n");
} else if (load_attr.insns_cnt >= BPF_MAXINSNS) {
} else if (load_attr.insn_cnt >= BPF_MAXINSNS) {
pr_warn("Program too large (%zu insns), at most %d insns\n",
load_attr.insns_cnt, BPF_MAXINSNS);
load_attr.insn_cnt, BPF_MAXINSNS);
ret = -LIBBPF_ERRNO__PROG2BIG;
} else if (load_attr.prog_type != BPF_PROG_TYPE_KPROBE) {
/* Wrong program type? */
@ -6926,7 +6922,9 @@ retry_load:
load_attr.prog_type = BPF_PROG_TYPE_KPROBE;
load_attr.expected_attach_type = 0;
fd = bpf_load_program_xattr(&load_attr, NULL, 0);
load_attr.log_buf = NULL;
load_attr.log_buf_sz = 0;
fd = libbpf__bpf_prog_load(&load_attr);
if (fd >= 0) {
close(fd);
ret = -LIBBPF_ERRNO__PROGTYPE;

29
tools/lib/bpf/libbpf_internal.h
View File

@ -151,6 +151,35 @@ int parse_cpu_mask_file(const char *fcpu, bool **mask, int *mask_sz);
int libbpf__load_raw_btf(const char *raw_types, size_t types_len,
const char *str_sec, size_t str_len);
struct bpf_prog_load_params {
enum bpf_prog_type prog_type;
enum bpf_attach_type expected_attach_type;
const char *name;
const struct bpf_insn *insns;
size_t insn_cnt;
const char *license;
__u32 kern_version;
__u32 attach_prog_fd;
__u32 attach_btf_id;
__u32 prog_ifindex;
__u32 prog_btf_fd;
__u32 prog_flags;
__u32 func_info_rec_size;
const void *func_info;
__u32 func_info_cnt;
__u32 line_info_rec_size;
const void *line_info;
__u32 line_info_cnt;
__u32 log_level;
char *log_buf;
size_t log_buf_sz;
};
int libbpf__bpf_prog_load(const struct bpf_prog_load_params *load_attr);
int bpf_object__section_size(const struct bpf_object *obj, const char *name,
__u32 *size);
int bpf_object__variable_offset(const struct bpf_object *obj, const char *name,