diff mbox series

[bpf-next,v2,3/5] bpf: allow sleepable uprobe programs to attach

Message ID 611d4629dc959f9d327693180b0d106dcefe949f.1651532419.git.delyank@fb.com (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series sleepable uprobe support | expand

Checks

Context Check Description
bpf/vmtest-bpf-next-PR success PR summary
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix success Link
netdev/cover_letter success Series has a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 60 this patch: 60
netdev/cc_maintainers warning 14 maintainers not CCed: songliubraving@fb.com acme@kernel.org jolsa@kernel.org linux-perf-users@vger.kernel.org netdev@vger.kernel.org kafai@fb.com mingo@redhat.com mark.rutland@arm.com yhs@fb.com namhyung@kernel.org peterz@infradead.org john.fastabend@gmail.com kpsingh@kernel.org alexander.shishkin@linux.intel.com
netdev/build_clang success Errors and warnings before: 9 this patch: 9
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 60 this patch: 60
netdev/checkpatch warning WARNING: line length of 111 exceeds 80 columns WARNING: line length of 84 exceeds 80 columns WARNING: line length of 85 exceeds 80 columns
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
bpf/vmtest-bpf-next-VM_Test-1 success Logs for Kernel LATEST on ubuntu-latest + selftests
bpf/vmtest-bpf-next-VM_Test-2 success Logs for Kernel LATEST on z15 + selftests

Commit Message

Delyan Kratunov May 2, 2022, 11:09 p.m. UTC 
uprobe and kprobe programs have the same program type, KPROBE, which is
currently not allowed to load sleepable programs.

To avoid adding a new UPROBE type, we instead allow sleepable KPROBE
programs to load and defer the is-it-actually-a-uprobe-program check
to attachment time, where we're already validating the corresponding
perf_event.

A corollary of this patch is that you can now load a sleepable kprobe
program but cannot attach it.

Signed-off-by: Delyan Kratunov <delyank@fb.com>
---
 kernel/bpf/verifier.c |  4 ++--
 kernel/events/core.c  | 16 ++++++++++------
 2 files changed, 12 insertions(+), 8 deletions(-)

Comments

Andrii Nakryiko May 9, 2022, 11:52 p.m. UTC | #1 
On Mon, May 2, 2022 at 4:09 PM Delyan Kratunov <delyank@fb.com> wrote:
>
> uprobe and kprobe programs have the same program type, KPROBE, which is
> currently not allowed to load sleepable programs.
>
> To avoid adding a new UPROBE type, we instead allow sleepable KPROBE
> programs to load and defer the is-it-actually-a-uprobe-program check
> to attachment time, where we're already validating the corresponding
> perf_event.
>
> A corollary of this patch is that you can now load a sleepable kprobe
> program but cannot attach it.
>
> Signed-off-by: Delyan Kratunov <delyank@fb.com>
> ---

LGTM.

Acked-by: Andrii Nakryiko <andrii@kernel.org>

>  kernel/bpf/verifier.c |  4 ++--
>  kernel/events/core.c  | 16 ++++++++++------
>  2 files changed, 12 insertions(+), 8 deletions(-)
>

[...]
diff mbox series

Patch

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 813f6ee80419..82b37a1a8a33 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -14571,8 +14571,8 @@  static int check_attach_btf_id(struct bpf_verifier_env *env)
 	}
 
 	if (prog->aux->sleepable && prog->type != BPF_PROG_TYPE_TRACING &&
-	    prog->type != BPF_PROG_TYPE_LSM) {
-		verbose(env, "Only fentry/fexit/fmod_ret and lsm programs can be sleepable\n");
+	    prog->type != BPF_PROG_TYPE_LSM && prog->type != BPF_PROG_TYPE_KPROBE) {
+		verbose(env, "Only fentry/fexit/fmod_ret, lsm, and kprobe/uprobe programs can be sleepable\n");
 		return -EINVAL;
 	}
 
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 23bb19716ad3..bd09c4152a3b 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -10069,26 +10069,30 @@  static inline bool perf_event_is_tracing(struct perf_event *event)
 int perf_event_set_bpf_prog(struct perf_event *event, struct bpf_prog *prog,
 			    u64 bpf_cookie)
 {
-	bool is_kprobe, is_tracepoint, is_syscall_tp;
+	bool is_kprobe, is_uprobe, is_tracepoint, is_syscall_tp;
 
 	if (!perf_event_is_tracing(event))
 		return perf_event_set_bpf_handler(event, prog, bpf_cookie);
 
-	is_kprobe = event->tp_event->flags & TRACE_EVENT_FL_UKPROBE;
+	is_kprobe = event->tp_event->flags & TRACE_EVENT_FL_KPROBE;
+	is_uprobe = event->tp_event->flags & TRACE_EVENT_FL_UPROBE;
 	is_tracepoint = event->tp_event->flags & TRACE_EVENT_FL_TRACEPOINT;
 	is_syscall_tp = is_syscall_trace_event(event->tp_event);
-	if (!is_kprobe && !is_tracepoint && !is_syscall_tp)
+	if (!is_kprobe && !is_uprobe && !is_tracepoint && !is_syscall_tp)
 		/* bpf programs can only be attached to u/kprobe or tracepoint */
 		return -EINVAL;
 
-	if ((is_kprobe && prog->type != BPF_PROG_TYPE_KPROBE) ||
+	if (((is_kprobe || is_uprobe) && prog->type != BPF_PROG_TYPE_KPROBE) ||
 	    (is_tracepoint && prog->type != BPF_PROG_TYPE_TRACEPOINT) ||
 	    (is_syscall_tp && prog->type != BPF_PROG_TYPE_TRACEPOINT))
 		return -EINVAL;
 
+	if (prog->type == BPF_PROG_TYPE_KPROBE && prog->aux->sleepable && !is_uprobe)
+		/* only uprobe programs are allowed to be sleepable */
+		return -EINVAL;
+
 	/* Kprobe override only works for kprobes, not uprobes. */
-	if (prog->kprobe_override &&
-	    !(event->tp_event->flags & TRACE_EVENT_FL_KPROBE))
+	if (prog->kprobe_override && !is_kprobe)
 		return -EINVAL;
 
 	if (is_tracepoint || is_syscall_tp) {