| Message ID | 20220801175407.2647869-2-haoluo@google.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | BPF |
| Headers | show |
| Series | bpf: rstat: cgroup hierarchical stats | expand |
> From: Hao Luo [mailto:haoluo@google.com] > Sent: Monday, August 1, 2022 7:54 PM > From: Benjamin Tissoires <benjamin.tissoires@redhat.com> > > From: Benjamin Tissoires <benjamin.tissoires@redhat.com> > > This allows to declare a kfunc as sleepable and prevents its use in > a non sleepable program. > > Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com> > Co-developed-by: Yosry Ahmed <yosryahmed@google.com> > Signed-off-by: Yosry Ahmed <yosryahmed@google.com> > Signed-off-by: Hao Luo <haoluo@google.com> Thanks, helpful also for me. Reviewed-by: Roberto Sassu <roberto.sassu@huawei.com> Roberto > --- > Documentation/bpf/kfuncs.rst | 6 ++++++ > include/linux/btf.h | 1 + > kernel/bpf/btf.c | 9 +++++++++ > 3 files changed, 16 insertions(+) > > diff --git a/Documentation/bpf/kfuncs.rst b/Documentation/bpf/kfuncs.rst > index c0b7dae6dbf5..c8b21de1c772 100644 > --- a/Documentation/bpf/kfuncs.rst > +++ b/Documentation/bpf/kfuncs.rst > @@ -146,6 +146,12 @@ that operate (change some property, perform some > operation) on an object that > was obtained using an acquire kfunc. Such kfuncs need an unchanged pointer to > ensure the integrity of the operation being performed on the expected object. > > +2.4.6 KF_SLEEPABLE flag > +----------------------- > + > +The KF_SLEEPABLE flag is used for kfuncs that may sleep. Such kfuncs can only > +be called by sleepable BPF programs (BPF_F_SLEEPABLE). > + > 2.5 Registering the kfuncs > -------------------------- > > diff --git a/include/linux/btf.h b/include/linux/btf.h > index cdb376d53238..976cbdd2981f 100644 > --- a/include/linux/btf.h > +++ b/include/linux/btf.h > @@ -49,6 +49,7 @@ > * for this case. > */ > #define KF_TRUSTED_ARGS (1 << 4) /* kfunc only takes trusted pointer > arguments */ > +#define KF_SLEEPABLE (1 << 5) /* kfunc may sleep */ > > struct btf; > struct btf_member; > diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c > index 7e64447659f3..d3e4c86b8fcd 100644 > --- a/kernel/bpf/btf.c > +++ b/kernel/bpf/btf.c > @@ -6175,6 +6175,7 @@ static int btf_check_func_arg_match(struct > bpf_verifier_env *env, > { > enum bpf_prog_type prog_type = resolve_prog_type(env->prog); > bool rel = false, kptr_get = false, trusted_arg = false; > + bool sleepable = false; > struct bpf_verifier_log *log = &env->log; > u32 i, nargs, ref_id, ref_obj_id = 0; > bool is_kfunc = btf_is_kernel(btf); > @@ -6212,6 +6213,7 @@ static int btf_check_func_arg_match(struct > bpf_verifier_env *env, > rel = kfunc_flags & KF_RELEASE; > kptr_get = kfunc_flags & KF_KPTR_GET; > trusted_arg = kfunc_flags & KF_TRUSTED_ARGS; > + sleepable = kfunc_flags & KF_SLEEPABLE; > } > > /* check that BTF function arguments match actual types that the > @@ -6419,6 +6421,13 @@ static int btf_check_func_arg_match(struct > bpf_verifier_env *env, > func_name); > return -EINVAL; > } > + > + if (sleepable && !env->prog->aux->sleepable) { > + bpf_log(log, "kernel function %s is sleepable but the program is > not\n", > + func_name); > + return -EINVAL; > + } > + > /* returns argument register number > 0 in case of reference release > kfunc */ > return rel ? ref_regno : 0; > } > -- > 2.37.1.455.g008518b4e5-goog
diff --git a/Documentation/bpf/kfuncs.rst b/Documentation/bpf/kfuncs.rst index c0b7dae6dbf5..c8b21de1c772 100644 --- a/Documentation/bpf/kfuncs.rst +++ b/Documentation/bpf/kfuncs.rst @@ -146,6 +146,12 @@ that operate (change some property, perform some operation) on an object that was obtained using an acquire kfunc. Such kfuncs need an unchanged pointer to ensure the integrity of the operation being performed on the expected object. +2.4.6 KF_SLEEPABLE flag +----------------------- + +The KF_SLEEPABLE flag is used for kfuncs that may sleep. Such kfuncs can only +be called by sleepable BPF programs (BPF_F_SLEEPABLE). + 2.5 Registering the kfuncs -------------------------- diff --git a/include/linux/btf.h b/include/linux/btf.h index cdb376d53238..976cbdd2981f 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -49,6 +49,7 @@ * for this case. */ #define KF_TRUSTED_ARGS (1 << 4) /* kfunc only takes trusted pointer arguments */ +#define KF_SLEEPABLE (1 << 5) /* kfunc may sleep */ struct btf; struct btf_member; diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 7e64447659f3..d3e4c86b8fcd 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -6175,6 +6175,7 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, { enum bpf_prog_type prog_type = resolve_prog_type(env->prog); bool rel = false, kptr_get = false, trusted_arg = false; + bool sleepable = false; struct bpf_verifier_log *log = &env->log; u32 i, nargs, ref_id, ref_obj_id = 0; bool is_kfunc = btf_is_kernel(btf); @@ -6212,6 +6213,7 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, rel = kfunc_flags & KF_RELEASE; kptr_get = kfunc_flags & KF_KPTR_GET; trusted_arg = kfunc_flags & KF_TRUSTED_ARGS; + sleepable = kfunc_flags & KF_SLEEPABLE; } /* check that BTF function arguments match actual types that the @@ -6419,6 +6421,13 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, func_name); return -EINVAL; } + + if (sleepable && !env->prog->aux->sleepable) { + bpf_log(log, "kernel function %s is sleepable but the program is not\n", + func_name); + return -EINVAL; + } + /* returns argument register number > 0 in case of reference release kfunc */ return rel ? ref_regno : 0; }