From mboxrd@z Thu Jan 1 00:00:00 1970 From: AKASHI Takahiro Subject: Re: [PATCH] selftests/seccomp: build on aarch64, document ABI Date: Thu, 10 Sep 2015 19:35:33 +0900 Message-ID: <55F15CF5.3000409@linaro.org> References: <20150909193025.GA29244@www.outflux.net> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20150909193025.GA29244@www.outflux.net> Sender: linux-kernel-owner@vger.kernel.org To: Kees Cook , linux-arm-kernel@lists.infradead.org Cc: Bamvor Zhang Jian , Arnd Bergmann , Shuah Khan , Andy Lutomirski , Will Drewry , linux-api@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-api@vger.kernel.org On 09/10/2015 04:30 AM, Kees Cook wrote: > The syscall ABI is inconsistent on aarch64 compat, so at least we should > document it in the seccomp_bpf tests. > > Signed-off-by: Kees Cook > --- > Can someone with access to native aarch64 double-check this for me? I > think we need to change these tests to pass if it's expected, but the > compat behavior seems bad. It means compat code will break under an > aarch64 kernel, when dealing with syscalls, like through seccomp. > --- > tools/testing/selftests/seccomp/seccomp_bpf.c | 15 +++++++++++++-- > 1 file changed, 13 insertions(+), 2 deletions(-) > > diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c > index 770f47adf295..866ff42e000d 100644 > --- a/tools/testing/selftests/seccomp/seccomp_bpf.c > +++ b/tools/testing/selftests/seccomp/seccomp_bpf.c > @@ -33,6 +33,10 @@ > #include > #include > > +#if defined(__aarch64__) && !defined(__NR_poll) > +# define __NR_poll 0x49 > +#endif > + > #include "test_harness.h" > > #ifndef PR_SET_PTRACER > @@ -2124,10 +2128,17 @@ TEST(syscall_restart) > ASSERT_EQ(SIGTRAP, WSTOPSIG(status)); > ASSERT_EQ(PTRACE_EVENT_SECCOMP, (status >> 16)); > ASSERT_EQ(0, ptrace(PTRACE_GETEVENTMSG, child_pid, NULL, &msg)); > - ASSERT_EQ(0x200, msg); > + > + /* > + * FIXME: > + * - native ARM does not expose true syscall. > + * - compat ARM on ARM64 does expose true syscall. > + * - native ARM64 hides true syscall even from seccomp. Are you sure about the last line? The kernel pushes __NR_compat_restart_syscall to w7 in compat mode, while __NR_restart_syscall to x8 in native mode. But it is the only difference, as far as I understand, in terms of restarting a system call. So the behavior should be basically the same. -Takahiro AKASHI > + */ > + ASSERT_EQ(0x200, msg); /* This will fail on native arm64. */ > ret = get_syscall(_metadata, child_pid); > #if defined(__arm__) > - /* FIXME: ARM does not expose true syscall in registers. */ > + /* This will fail on arm64 in compat mode. */ > EXPECT_EQ(__NR_poll, ret); > #else > EXPECT_EQ(__NR_restart_syscall, ret); >