Commit 1e12d3ef authored by David Vernet's avatar David Vernet Committed by Alexei Starovoitov
Browse files

bpf: Allow BPF_PROG_TYPE_STRUCT_OPS programs to be sleepable 



BPF struct_ops programs currently cannot be marked as sleepable. This
need not be the case -- struct_ops programs can be sleepable, and e.g.
invoke kfuncs that export the KF_SLEEPABLE flag. So as to allow future
struct_ops programs to invoke such kfuncs, this patch updates the
verifier to allow struct_ops programs to be sleepable. A follow-on patch
will add support to libbpf for specifying struct_ops.s as a sleepable
struct_ops program, and then another patch will add testcases to the
dummy_st_ops selftest suite which test sleepable struct_ops behavior.

Signed-off-by: default avatarDavid Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230125164735.785732-2-void@manifault.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 2514a312

kernel/bpf/verifier.c

+3 −2
Original line number Diff line number Diff line
@@ -17114,7 +17114,8 @@ static bool can_be_sleepable(struct bpf_prog *prog) 
		}

	}

	return prog->type == BPF_PROG_TYPE_LSM ||

	       prog->type == BPF_PROG_TYPE_KPROBE; /* only for uprobes */

	       prog->type == BPF_PROG_TYPE_KPROBE /* only for uprobes */ ||

	       prog->type == BPF_PROG_TYPE_STRUCT_OPS;

}



static int check_attach_btf_id(struct bpf_verifier_env *env)
@@ -17136,7 +17137,7 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) 
	}



	if (prog->aux->sleepable && !can_be_sleepable(prog)) {

		verbose(env, "Only fentry/fexit/fmod_ret, lsm, iter and uprobe programs can be sleepable\n");

		verbose(env, "Only fentry/fexit/fmod_ret, lsm, iter, uprobe, and struct_ops programs can be sleepable\n");

		return -EINVAL;

	}

tools/testing/selftests/bpf/verifier/sleepable.c

+1 −1
Original line number Diff line number Diff line
@@ -85,7 +85,7 @@ 
	.expected_attach_type = BPF_TRACE_RAW_TP,

	.kfunc = "sched_switch",

	.result = REJECT,

	.errstr = "Only fentry/fexit/fmod_ret, lsm, iter and uprobe programs can be sleepable",

	.errstr = "Only fentry/fexit/fmod_ret, lsm, iter, uprobe, and struct_ops programs can be sleepable",

	.flags = BPF_F_SLEEPABLE,

	.runs = -1,

},