From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from 69-171-232-181.mail-mxout.facebook.com (69-171-232-181.mail-mxout.facebook.com [69.171.232.181]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 317A8140E5F for ; Fri, 18 Sep 2026 04:43:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=69.171.232.181 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789706630; cv=none; b=qHlmT8kGzKIJWPwCFWEcjbh4/YNLbj2lqcYcudKhYmRYpdOE6PA50aFQ8o2z8tVunKifq4eX4iy+CkPlaLx/ww9KxRhlKVvud+sUJ+NVvszIm721SOjsNTkO694hzzqN9mhYB5QOGoczLpfBUubB8pBcs3DiUFDdrvb1QYE14k8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789706630; c=relaxed/simple; bh=yncN8hZlG4LelMujTwalECY9VeifeEEygGoKGqwemkg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=VTSJVX/arrGfd3RPnjcvg/5zn0y5P36OMye+mPbPjg99TfU9SVeyUrNetutwIjNVlPyr7l4ia3tu4eiAFAANUYA2aRd5cL2bns9Qy4ZJ3IzQHVI7javjdCNTHOGjUQ8KEDiI/vmzM80zKoU61aC5JuCXX20TlEx4r5Kw6IOip8Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.dev; spf=fail smtp.mailfrom=linux.dev; arc=none smtp.client-ip=69.171.232.181 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=linux.dev Received: by devvm16039.vll0.facebook.com (Postfix, from userid 128203) id 9BFB22B7C8BFC6; Thu, 17 Sep 2026 21:43:42 -0700 (PDT) From: Yonghong Song To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Eduard Zingerman , kernel-team@fb.com Subject: [PATCH bpf-next v2 20/20] selftests/bpf: Load an exception cleanup program from a light skeleton Date: Thu, 17 Sep 2026 21:43:42 -0700 Message-ID: <20260918044342.3294235-1-yonghong.song@linux.dev> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260918044156.3283973-1-yonghong.song@linux.dev> References: <20260918044156.3283973-1-yonghong.song@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable For a light skeleton, libbpf hands the records to bpf_gen__prog_load(), which writes them into a blob and emits a loader program that issues BPF_PROG_LOAD from inside the kernel. Nothing about that is shared with t= he ordinary path: the attr is built field by field, and the kfunc names are resolved by the loader program when it runs. exceptions_cleanup_light.c is the smallest program that can tell whether = a table survives that trip: one record covering the bpf_throw() call itself= , one pad that sets a bit and resumes. If the table arrives, the pad runs a= nd the cookie comes back; if it does not, the program does not load at all. Signed-off-by: Yonghong Song --- tools/testing/selftests/bpf/Makefile | 2 +- .../selftests/bpf/exceptions_cleanup.h | 3 ++ .../bpf/prog_tests/exceptions_cleanup.c | 28 +++++++++++++ .../bpf/progs/exceptions_cleanup_light.c | 39 +++++++++++++++++++ 4 files changed, 71 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/bpf/progs/exceptions_cleanup_= light.c diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftes= ts/bpf/Makefile index 7ea5ba1df29e..981cc2643049 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -523,7 +523,7 @@ LINKED_SKELS :=3D test_static_linked.skel.h linked_fu= ncs.skel.h \ LSKELS :=3D fexit_sleep.c trace_printk.c trace_vprintk.c map_ptr_kern.c = \ core_kern.c core_kern_overflow.c test_ringbuf.c \ test_ringbuf_n.c test_ringbuf_map_key.c test_ringbuf_write.c \ - test_ringbuf_overwrite.c + test_ringbuf_overwrite.c exceptions_cleanup_light.c =20 LSKELS_SIGNED :=3D fentry_test.c fexit_test.c atomics.c =20 diff --git a/tools/testing/selftests/bpf/exceptions_cleanup.h b/tools/tes= ting/selftests/bpf/exceptions_cleanup.h index 5896cf83d15e..0c088d96ca01 100644 --- a/tools/testing/selftests/bpf/exceptions_cleanup.h +++ b/tools/testing/selftests/bpf/exceptions_cleanup.h @@ -32,6 +32,9 @@ #define RAN_RESUME_ALIAS 0x8000 #define RAN_PAD_TAIL_CALL 0x10000 =20 +/* progs/exceptions_cleanup_light.c: the one pad it has. */ +#define RAN_LIGHT 0x1 + #define CLEANUP_REC(begin, end, landing_pad) \ ".pushsection .bpf_cleanup,\"a\",@progbits;" \ ".long " begin ";" \ diff --git a/tools/testing/selftests/bpf/prog_tests/exceptions_cleanup.c = b/tools/testing/selftests/bpf/prog_tests/exceptions_cleanup.c index ffc0b9519168..ad0ff949f10d 100644 --- a/tools/testing/selftests/bpf/prog_tests/exceptions_cleanup.c +++ b/tools/testing/selftests/bpf/prog_tests/exceptions_cleanup.c @@ -8,6 +8,7 @@ #include "exceptions_cleanup_freplace.skel.h" #include "exceptions_cleanup_pad_freplace.skel.h" #include "exceptions_cleanup_ext_table.skel.h" +#include "exceptions_cleanup_light.lskel.h" =20 /* foo3 threw: every frame that has a pad ran it. */ #define PADS_FOO3_THREW \ @@ -170,6 +171,30 @@ static void test_ext_table(struct exceptions_cleanup= _shapes *skel) exceptions_cleanup_ext_table__destroy(fr); } =20 +static void test_light_skeleton(void) +{ + struct exceptions_cleanup_light_lskel *skel; + __u64 ctx =3D 0; + int err; + + LIBBPF_OPTS(bpf_test_run_opts, topts, + .ctx_in =3D &ctx, + .ctx_size_in =3D sizeof(ctx), + ); + + skel =3D exceptions_cleanup_light_lskel__open_and_load(); + if (!ASSERT_OK_PTR(skel, "light open_and_load")) + return; + + err =3D bpf_prog_test_run_opts(skel->progs.entry_light.prog_fd, &topts)= ; + if (!ASSERT_OK(err, "run")) + goto out; + ASSERT_EQ(topts.retval, THROW_COOKIE, "retval"); + ASSERT_EQ(skel->bss->pads_ran, RAN_LIGHT, "pads_ran"); +out: + exceptions_cleanup_light_lskel__destroy(skel); +} + static void test_shapes(void) { struct exceptions_cleanup_shapes *skel; @@ -387,6 +412,9 @@ void test_exceptions_cleanup(void) =20 exceptions_cleanup__destroy(skel); =20 + if (test__start_subtest("light_skeleton")) + test_light_skeleton(); + test_shapes(); =20 RUN_TESTS(exceptions_cleanup_fail); diff --git a/tools/testing/selftests/bpf/progs/exceptions_cleanup_light.c= b/tools/testing/selftests/bpf/progs/exceptions_cleanup_light.c new file mode 100644 index 000000000000..de7ae478d67f --- /dev/null +++ b/tools/testing/selftests/bpf/progs/exceptions_cleanup_light.c @@ -0,0 +1,39 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */ +#include +#include +#include "bpf_misc.h" +#include "exceptions_cleanup.h" + +static __used __noinline void __kfunc_btf_anchor(void) +{ + bpf_throw(0); + bpf_preempt_disable(); + bpf_preempt_enable(); + bpf_unwind_resume(); +} + +__u64 pads_ran =3D 0; + +SEC("syscall") +__naked int entry_light(void) +{ + asm volatile ( + "call bpf_preempt_disable;" + "r1 =3D %[cookie];" +"1:" "call bpf_throw;" /* cleanup region */ +"2:" + "exit;" +"3:" /* landing pad */ + "call bpf_preempt_enable;" + PAD_RAN("%[ran]") + "call bpf_unwind_resume;" + "exit;" + CLEANUP_REC("1b", "2b", "3b") + : + : [cookie]"i"(THROW_COOKIE), [ran]"i"(RAN_LIGHT), + __imm_addr(pads_ran) + : __clobber_all); +} + +char _license[] SEC("license") =3D "GPL"; --=20 2.53.0-Meta