| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Date: Mon, 7 Dec 2020 19:18:57 -0800
From: Yonghong Song <yhs@...com>
To: Brendan Jackman <jackmanb@...gle.com>, <bpf@...r.kernel.org>
CC: Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
KP Singh <kpsingh@...omium.org>,
Florent Revest <revest@...omium.org>,
<linux-kernel@...r.kernel.org>, Jann Horn <jannh@...gle.com>
Subject: Re: [PATCH bpf-next v4 10/11] bpf: Add tests for new BPF atomic
operations
On 12/7/20 8:07 AM, Brendan Jackman wrote:
> The prog_test that's added depends on Clang/LLVM features added by
> Yonghong in commit 286daafd6512 (was https://reviews.llvm.org/D72184 ).
>
> Note the use of a define called ENABLE_ATOMICS_TESTS: this is used
> to:
>
> - Avoid breaking the build for people on old versions of Clang
> - Avoid needing separate lists of test objects for no_alu32, where
> atomics are not supported even if Clang has the feature.
>
> The atomics_test.o BPF object is built unconditionally both for
> test_progs and test_progs-no_alu32. For test_progs, if Clang supports
> atomics, ENABLE_ATOMICS_TESTS is defined, so it includes the proper
> test code. Otherwise, progs and global vars are defined anyway, as
> stubs; this means that the skeleton user code still builds.
>
> The atomics_test.o userspace object is built once and used for both
> test_progs and test_progs-no_alu32. A variable called skip_tests is
> defined in the BPF object's data section, which tells the userspace
> object whether to skip the atomics test.
>
> Signed-off-by: Brendan Jackman <jackmanb@...gle.com>
Ack with minor comments below.
Acked-by: Yonghong Song <yhs@...com>
> ---
> tools/testing/selftests/bpf/Makefile | 10 +
> .../selftests/bpf/prog_tests/atomics.c | 246 ++++++++++++++++++
> tools/testing/selftests/bpf/progs/atomics.c | 154 +++++++++++
> .../selftests/bpf/verifier/atomic_and.c | 77 ++++++
> .../selftests/bpf/verifier/atomic_cmpxchg.c | 96 +++++++
> .../selftests/bpf/verifier/atomic_fetch_add.c | 106 ++++++++
> .../selftests/bpf/verifier/atomic_or.c | 77 ++++++
> .../selftests/bpf/verifier/atomic_xchg.c | 46 ++++
> .../selftests/bpf/verifier/atomic_xor.c | 77 ++++++
> 9 files changed, 889 insertions(+)
> create mode 100644 tools/testing/selftests/bpf/prog_tests/atomics.c
> create mode 100644 tools/testing/selftests/bpf/progs/atomics.c
> create mode 100644 tools/testing/selftests/bpf/verifier/atomic_and.c
> create mode 100644 tools/testing/selftests/bpf/verifier/atomic_cmpxchg.c
> create mode 100644 tools/testing/selftests/bpf/verifier/atomic_fetch_add.c
> create mode 100644 tools/testing/selftests/bpf/verifier/atomic_or.c
> create mode 100644 tools/testing/selftests/bpf/verifier/atomic_xchg.c
> create mode 100644 tools/testing/selftests/bpf/verifier/atomic_xor.c
>
> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> index ac25ba5d0d6c..13bc1d736164 100644
> --- a/tools/testing/selftests/bpf/Makefile
> +++ b/tools/testing/selftests/bpf/Makefile
> @@ -239,6 +239,12 @@ BPF_CFLAGS = -g -D__TARGET_ARCH_$(SRCARCH) $(MENDIAN) \
> -I$(INCLUDE_DIR) -I$(CURDIR) -I$(APIDIR) \
> -I$(abspath $(OUTPUT)/../usr/include)
>
> +# BPF atomics support was added to Clang in llvm-project commit 286daafd6512
> +# (release 12.0.0).
> +BPF_ATOMICS_SUPPORTED = $(shell \
> + echo "int x = 0; int foo(void) { return __sync_val_compare_and_swap(&x, 1, 2); }" \
> + | $(CLANG) -x cpp-output -S -target bpf -mcpu=v3 - -o /dev/null && echo 1 || echo 0)
'-x c' here more intuitive?
> +
> CLANG_CFLAGS = $(CLANG_SYS_INCLUDES) \
> -Wno-compare-distinct-pointer-types
>
> @@ -399,11 +405,15 @@ TRUNNER_EXTRA_FILES := $(OUTPUT)/urandom_read $(OUTPUT)/bpf_testmod.ko \
> $(wildcard progs/btf_dump_test_case_*.c)
> TRUNNER_BPF_BUILD_RULE := CLANG_BPF_BUILD_RULE
> TRUNNER_BPF_CFLAGS := $(BPF_CFLAGS) $(CLANG_CFLAGS)
> +ifeq ($(BPF_ATOMICS_SUPPORTED),1)
> + TRUNNER_BPF_CFLAGS += -DENABLE_ATOMICS_TESTS
> +endif
> TRUNNER_BPF_LDFLAGS := -mattr=+alu32
> $(eval $(call DEFINE_TEST_RUNNER,test_progs))
>
> # Define test_progs-no_alu32 test runner.
> TRUNNER_BPF_BUILD_RULE := CLANG_NOALU32_BPF_BUILD_RULE
> +TRUNNER_BPF_CFLAGS := $(BPF_CFLAGS) $(CLANG_CFLAGS)
> TRUNNER_BPF_LDFLAGS :=
> $(eval $(call DEFINE_TEST_RUNNER,test_progs,no_alu32))
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/atomics.c b/tools/testing/selftests/bpf/prog_tests/atomics.c
> new file mode 100644
> index 000000000000..c841a3abc2f7
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/atomics.c
> @@ -0,0 +1,246 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <test_progs.h>
> +
> +#include "atomics.skel.h"
> +
> +static void test_add(struct atomics *skel)
> +{
> + int err, prog_fd;
> + __u32 duration = 0, retval;
> + struct bpf_link *link;
> +
> + link = bpf_program__attach(skel->progs.add);
> + if (CHECK(IS_ERR(link), "attach(add)", "err: %ld\n", PTR_ERR(link)))
> + return;
> +
> + prog_fd = bpf_program__fd(skel->progs.add);
> + err = bpf_prog_test_run(prog_fd, 1, NULL, 0,
> + NULL, NULL, &retval, &duration);
> + if (CHECK(err || retval, "test_run add",
> + "err %d errno %d retval %d duration %d\n", err, errno, retval, duration))
> + goto cleanup;
> +
> + ASSERT_EQ(skel->data->add64_value, 3, "add64_value");
> + ASSERT_EQ(skel->bss->add64_result, 1, "add64_result");
> +
> + ASSERT_EQ(skel->data->add32_value, 3, "add32_value");
> + ASSERT_EQ(skel->bss->add32_result, 1, "add32_result");
> +
> + ASSERT_EQ(skel->bss->add_stack_value_copy, 3, "add_stack_value");
> + ASSERT_EQ(skel->bss->add_stack_result, 1, "add_stack_result");
> +
> + ASSERT_EQ(skel->data->add_noreturn_value, 3, "add_noreturn_value");
> +
> +cleanup:
> + bpf_link__destroy(link);
> +}
> +
[...]
> +
> +__u64 xchg64_value = 1;
> +__u64 xchg64_result = 0;
> +__u32 xchg32_value = 1;
> +__u32 xchg32_result = 0;
> +
> +SEC("fentry/bpf_fentry_test1")
> +int BPF_PROG(xchg, int a)
> +{
> +#ifdef ENABLE_ATOMICS_TESTS
> + __u64 val64 = 2;
> + __u32 val32 = 2;
> +
> + __atomic_exchange(&xchg64_value, &val64, &xchg64_result, __ATOMIC_RELAXED);
> + __atomic_exchange(&xchg32_value, &val32, &xchg32_result, __ATOMIC_RELAXED);
Interesting to see this also works. I guess we probably won't advertise
this, right? Currently for LLVM, the memory ordering parameter is ignored.
> +#endif
> +
> + return 0;
> +}
[...]
Powered by blists - more mailing lists