libbpf: Support sleepable progs

Pass request to load program as sleepable via ".s" suffix in the section name.
If it happens in the future that all map types and helpers are allowed with
BPF_F_SLEEPABLE flag "fmod_ret/" and "lsm/" can be aliased to "fmod_ret.s/" and
"lsm.s/" to make all lsm and fmod_ret programs sleepable by default. The fentry
and fexit programs would always need to have sleepable vs non-sleepable
distinction, since not all fentry/fexit progs will be attached to sleepable
kernel functions.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: KP Singh <kpsingh@google.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200827220114.69225-5-alexei.starovoitov@gmail.com

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 8cdb2528482e9dce6be8554a5a71679044cc4d54..b688aadf09c5dea61c9349305ddeb23bc70152bf 100644 (file)
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -208,6 +208,7 @@ struct bpf_sec_def {
        bool is_exp_attach_type_optional;
        bool is_attachable;
        bool is_attach_btf;
+       bool is_sleepable;
        attach_fn_t attach_fn;
 };
 
@@ -6291,6 +6292,8 @@ __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz,
                        /* couldn't guess, but user might manually specify */
                        continue;
 
+               if (prog->sec_def->is_sleepable)
+                       prog->prog_flags |= BPF_F_SLEEPABLE;
                bpf_program__set_type(prog, prog->sec_def->prog_type);
                bpf_program__set_expected_attach_type(prog,
                                prog->sec_def->expected_attach_type);
@@ -7559,6 +7562,21 @@ static const struct bpf_sec_def section_defs[] = {
                .expected_attach_type = BPF_TRACE_FEXIT,
                .is_attach_btf = true,
                .attach_fn = attach_trace),
+       SEC_DEF("fentry.s/", TRACING,
+               .expected_attach_type = BPF_TRACE_FENTRY,
+               .is_attach_btf = true,
+               .is_sleepable = true,
+               .attach_fn = attach_trace),
+       SEC_DEF("fmod_ret.s/", TRACING,
+               .expected_attach_type = BPF_MODIFY_RETURN,
+               .is_attach_btf = true,
+               .is_sleepable = true,
+               .attach_fn = attach_trace),
+       SEC_DEF("fexit.s/", TRACING,
+               .expected_attach_type = BPF_TRACE_FEXIT,
+               .is_attach_btf = true,
+               .is_sleepable = true,
+               .attach_fn = attach_trace),
        SEC_DEF("freplace/", EXT,
                .is_attach_btf = true,
                .attach_fn = attach_trace),
@@ -7566,6 +7584,11 @@ static const struct bpf_sec_def section_defs[] = {
                .is_attach_btf = true,
                .expected_attach_type = BPF_LSM_MAC,
                .attach_fn = attach_lsm),
+       SEC_DEF("lsm.s/", LSM,
+               .is_attach_btf = true,
+               .is_sleepable = true,
+               .expected_attach_type = BPF_LSM_MAC,
+               .attach_fn = attach_lsm),
        SEC_DEF("iter/", TRACING,
                .expected_attach_type = BPF_TRACE_ITER,
                .is_attach_btf = true,
@@ -8288,7 +8311,7 @@ int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr,
 
                prog->prog_ifindex = attr->ifindex;
                prog->log_level = attr->log_level;
-               prog->prog_flags = attr->prog_flags;
+               prog->prog_flags |= attr->prog_flags;
                if (!first_prog)
                        first_prog = prog;
        }