[PATCH RFC v3 bpf-next 3/4] libbpf: support sleepable progs

[Alexei Starovoitov <alexei.starovoitov@gmail.com>]

From: Alexei Starovoitov <ast@kernel.org>

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>
Acked-by: KP Singh <kpsingh@google.com>
---
 tools/lib/bpf/libbpf.c | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 7f01be2b88b8..936ce9e1623a 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -209,6 +209,7 @@ 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;
 };
 
@@ -5451,6 +5452,8 @@ __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);
@@ -6646,6 +6649,21 @@ 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),
@@ -6653,6 +6671,11 @@ 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,
@@ -7294,7 +7317,7 @@ 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;
 	}
-- 
2.23.0