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Date: Fri, 17 Jan 2020 16:06:56 -0800
From: Alexei Starovoitov <ast@...nel.org>
To: <davem@...emloft.net>
CC: <daniel@...earbox.net>, <netdev@...r.kernel.org>,
<bpf@...r.kernel.org>, <kernel-team@...com>
Subject: [PATCH bpf-next 2/3] libbpf: Add support for program extensions
Add minimal support for program extensions. bpf_object_open_opts() needs to be
called with attach_prog_fd = target_prog_fd and BPF program extension needs to
have in .c file section definition like SEC("replace/func_to_be_replaced").
libbpf will search for "func_to_be_replaced" in the target_prog_fd's BTF and
will pass it in attach_btf_id to the kernel. This approach works for tests, but
more compex use case may need to request function name (and attach_btf_id that
kernel sees) to be more dynamic. Such API will be added in future patches.
Signed-off-by: Alexei Starovoitov <ast@...nel.org>
---
tools/include/uapi/linux/bpf.h | 1 +
tools/lib/bpf/bpf.c | 3 ++-
tools/lib/bpf/libbpf.c | 14 +++++++++++---
tools/lib/bpf/libbpf.h | 2 ++
tools/lib/bpf/libbpf.map | 2 ++
tools/lib/bpf/libbpf_probes.c | 1 +
6 files changed, 19 insertions(+), 4 deletions(-)
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 033d90a2282d..e81628eb059c 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -180,6 +180,7 @@ enum bpf_prog_type {
BPF_PROG_TYPE_CGROUP_SOCKOPT,
BPF_PROG_TYPE_TRACING,
BPF_PROG_TYPE_STRUCT_OPS,
+ BPF_PROG_TYPE_EXT,
};
enum bpf_attach_type {
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index ed42b006533c..c6dafe563176 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -237,7 +237,8 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
attr.expected_attach_type = load_attr->expected_attach_type;
if (attr.prog_type == BPF_PROG_TYPE_STRUCT_OPS) {
attr.attach_btf_id = load_attr->attach_btf_id;
- } else if (attr.prog_type == BPF_PROG_TYPE_TRACING) {
+ } 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 {
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index faab96a42141..bbf7e996553a 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -4837,7 +4837,8 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
load_attr.license = license;
if (prog->type == BPF_PROG_TYPE_STRUCT_OPS) {
load_attr.attach_btf_id = prog->attach_btf_id;
- } else if (prog->type == BPF_PROG_TYPE_TRACING) {
+ } 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 {
@@ -4918,7 +4919,8 @@ int bpf_program__load(struct bpf_program *prog, char *license, __u32 kern_ver)
{
int err = 0, fd, i, btf_id;
- if (prog->type == BPF_PROG_TYPE_TRACING) {
+ if (prog->type == BPF_PROG_TYPE_TRACING ||
+ prog->type == BPF_PROG_TYPE_EXT) {
btf_id = libbpf_find_attach_btf_id(prog);
if (btf_id <= 0)
return btf_id;
@@ -5092,7 +5094,8 @@ __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz,
bpf_program__set_type(prog, prog_type);
bpf_program__set_expected_attach_type(prog, attach_type);
- if (prog_type == BPF_PROG_TYPE_TRACING)
+ if (prog_type == BPF_PROG_TYPE_TRACING ||
+ prog_type == BPF_PROG_TYPE_EXT)
prog->attach_prog_fd = OPTS_GET(opts, attach_prog_fd, 0);
}
@@ -6166,6 +6169,7 @@ BPF_PROG_TYPE_FNS(xdp, BPF_PROG_TYPE_XDP);
BPF_PROG_TYPE_FNS(perf_event, BPF_PROG_TYPE_PERF_EVENT);
BPF_PROG_TYPE_FNS(tracing, BPF_PROG_TYPE_TRACING);
BPF_PROG_TYPE_FNS(struct_ops, BPF_PROG_TYPE_STRUCT_OPS);
+BPF_PROG_TYPE_FNS(extension, BPF_PROG_TYPE_EXT);
enum bpf_attach_type
bpf_program__get_expected_attach_type(struct bpf_program *prog)
@@ -6265,6 +6269,10 @@ static const struct bpf_sec_def section_defs[] = {
.expected_attach_type = BPF_TRACE_FEXIT,
.is_attach_btf = true,
.attach_fn = attach_trace),
+ SEC_DEF("replace/", EXT,
+ .expected_attach_type = 0,
+ .is_attach_btf = true,
+ .attach_fn = attach_trace),
BPF_PROG_SEC("xdp", BPF_PROG_TYPE_XDP),
BPF_PROG_SEC("perf_event", BPF_PROG_TYPE_PERF_EVENT),
BPF_PROG_SEC("lwt_in", BPF_PROG_TYPE_LWT_IN),
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 01639f9a1062..2a5e3b087002 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -318,6 +318,7 @@ LIBBPF_API int bpf_program__set_xdp(struct bpf_program *prog);
LIBBPF_API int bpf_program__set_perf_event(struct bpf_program *prog);
LIBBPF_API int bpf_program__set_tracing(struct bpf_program *prog);
LIBBPF_API int bpf_program__set_struct_ops(struct bpf_program *prog);
+LIBBPF_API int bpf_program__set_extension(struct bpf_program *prog);
LIBBPF_API enum bpf_prog_type bpf_program__get_type(struct bpf_program *prog);
LIBBPF_API void bpf_program__set_type(struct bpf_program *prog,
@@ -339,6 +340,7 @@ LIBBPF_API bool bpf_program__is_xdp(const struct bpf_program *prog);
LIBBPF_API bool bpf_program__is_perf_event(const struct bpf_program *prog);
LIBBPF_API bool bpf_program__is_tracing(const struct bpf_program *prog);
LIBBPF_API bool bpf_program__is_struct_ops(const struct bpf_program *prog);
+LIBBPF_API bool bpf_program__is_extension(const struct bpf_program *prog);
/*
* No need for __attribute__((packed)), all members of 'bpf_map_def'
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 64ec71ba41f1..b035122142bb 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -228,7 +228,9 @@ LIBBPF_0.0.7 {
bpf_prog_attach_xattr;
bpf_program__attach;
bpf_program__name;
+ bpf_program__is_extension;
bpf_program__is_struct_ops;
+ bpf_program__set_extension;
bpf_program__set_struct_ops;
btf__align_of;
libbpf_find_kernel_btf;
diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c
index 8cc992bc532a..b782ebef6ac9 100644
--- a/tools/lib/bpf/libbpf_probes.c
+++ b/tools/lib/bpf/libbpf_probes.c
@@ -107,6 +107,7 @@ probe_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns,
case BPF_PROG_TYPE_CGROUP_SOCKOPT:
case BPF_PROG_TYPE_TRACING:
case BPF_PROG_TYPE_STRUCT_OPS:
+ case BPF_PROG_TYPE_EXT:
default:
break;
}
--
2.23.0
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