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bpf: Allow BPF_PROG_TYPE_STRUCT_OPS programs to be sleepable

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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: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230125164735.785732-2-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
David Vernet 2023-01-25 10:47:32 -06:00 committed by Alexei Starovoitov
parent 2514a31241
commit 1e12d3ef47
2 changed files with 4 additions and 3 deletions
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5
kernel/bpf/verifier.c
View File

@ -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;
}

2
tools/testing/selftests/bpf/verifier/sleepable.c
View File

@ -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,
},