From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from 66-220-144-179.mail-mxout.facebook.com (66-220-144-179.mail-mxout.facebook.com [66.220.144.179]) (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 153E3412BFA for ; Wed, 23 Sep 2026 05:00:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=66.220.144.179 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790139644; cv=none; b=HazY0vGeSjniJLKkwXQMlHDWME1pM61i2yIxGcL0U3brpz4sn2ySVuxYROCglejt7lik+9nnetUGBXmHITSomSg7+xpgMVK4CQKIK9MeglPx2LeU+mUlZNXssD33ry3ymREgACDWNYeFhZvUBPRewLjXB4ZQSZtjxEkXx4ckP64= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790139644; c=relaxed/simple; bh=2QHSia9+hFDSSIDIFtFp5COQhRmMOvKmOj0hzbQPAeE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=U6xBfpXIZVHrc0SrhO/4X8118JEP7Wo5/OK0JDnzfrBqPYbtIB2AElD/WdA94oZ/A9BlngA1T16ZTiLQ9+KFBwCrCUO4z7Yh32NU22y1Zk9qOifem3fwtIV89MC15iG3EhD/GsvoWIBTZNF+G7DXMiZqkEaOtMa8ZugPoBjTddw= 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=66.220.144.179 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 53D7E2C8DADF61; Tue, 22 Sep 2026 22:00:34 -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 v5 21/21] selftests/bpf: Load an exception cleanup program from a light skeleton Date: Tue, 22 Sep 2026 22:00:34 -0700 Message-ID: <20260923050034.2427959-1-yonghong.song@linux.dev> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260923045846.2414643-1-yonghong.song@linux.dev> References: <20260923045846.2414643-1-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.skel | 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.skel b/tools/testing/se= lftests/bpf/Makefile.skel index 580d1d82c186..6d7518fa4018 100644 --- a/tools/testing/selftests/bpf/Makefile.skel +++ b/tools/testing/selftests/bpf/Makefile.skel @@ -33,7 +33,7 @@ LINKED_SKELS :=3D test_static_linked.skel.h linked_func= s.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 d6f63f147c4a..68f2d61a694b 100644 --- a/tools/testing/selftests/bpf/exceptions_cleanup.h +++ b/tools/testing/selftests/bpf/exceptions_cleanup.h @@ -36,6 +36,9 @@ #define RAN_GLOBAL_PAD 0x80000 #define RAN_PAD_R0 0x100000 =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 dbdb78b791e0..323ee8d72c91 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 \ @@ -171,6 +172,30 @@ 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; @@ -487,6 +512,9 @@ 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