linux-kernel - Re: test_syscall_vdso

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Date:   Tue, 26 Jun 2018 09:23:09 +0800
From:   Li Zhijian <zhijianx.li@...el.com>
To:     Andy Lutomirski <luto@...nel.org>
Cc:     Denys Vlasenko <dvlasenk@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@...r.kernel.org>,
        "Li, Philip" <philip.li@...el.com>,
        kernel test robot <xiaolong.ye@...el.com>
Subject: Re: test_syscall_vdso_32 [FAIL]

On 6/25/2018 11:40 PM, Andy Lutomirski wrote:
> On Mon, Jun 25, 2018 at 1:41 AM Li Zhijian <zhijianx.li@...el.com> wrote:
>> Hi
>>
>> Intel 0Day noticed that test_syscall_vdso_32 failed since 8bb2610bc4967f19672444a7b0407367f1540028(x86/entry/64/compat: Preserve r8-r11 in int $0x80)
>>
>> 2018-06-25 14:23:00 make run_tests -C x86
>> make: Entering directory '/usr/src/linux-selftests-x86_64-rhel-7.2-8bb2610bc4967f19672444a7b0407367f1540028/tools/testing/selftests/x86'
>> gcc -m32 -o /usr/src/linux-selftests-x86_64-rhel-7.2-8bb2610bc4967f19672444a7b0407367f1540028/tools/testing/selftests/x86/test_syscall_vdso_32 -O2 -g -std=gnu99 -pthread -Wall -no-pie -DCAN_BUILD_32 -DCAN_BUILD_64 test_syscall_vdso.c thunks_32.S -lrt -ldl -lm
>> TAP version 13
>> selftests: test_syscall_vdso_32
>> ========================================
>> [RUN]   Executing 6-argument 32-bit syscall via VDSO
>> [WARN]  Flags before=0000000000200ed7 id 0 00 o d i s z 0 a 0 p 1 c
>> [WARN]  Flags  after=0000000000200606 id 0 00 d i 0 0 p 1
>> [WARN]  Flags change=00000000000008d1 0 00 o s z 0 a 0 0 c
>> [OK]    Arguments are preserved across syscall
>> [NOTE]  R11 has changed:0000000000200606 - assuming clobbered by SYSRET insn
>> [OK]    R8..R15 did not leak kernel data
>> [RUN]   Executing 6-argument 32-bit syscall via INT 80
>> [OK]    Arguments are preserved across syscall
>> [FAIL]  R8 has changed:0000000000000000
>> [FAIL]  R9 has changed:0000000000000000
>> [FAIL]  R10 has changed:0000000000000000
>> [FAIL]  R11 has changed:0000000000000000
>> [RUN]   Executing 6-argument 32-bit syscall via VDSO
>> [WARN]  Flags before=0000000000200ed7 id 0 00 o d i s z 0 a 0 p 1 c
>> [WARN]  Flags  after=0000000000200606 id 0 00 d i 0 0 p 1
>> [WARN]  Flags change=00000000000008d1 0 00 o s z 0 a 0 0 c
>> [OK]    Arguments are preserved across syscall
>> [NOTE]  R11 has changed:0000000000200606 - assuming clobbered by SYSRET insn
>> [OK]    R8..R15 did not leak kernel data
>> [RUN]   Executing 6-argument 32-bit syscall via INT 80
>> [OK]    Arguments are preserved across syscall
>> [FAIL]  R8 has changed:0000000000000000
>> [FAIL]  R9 has changed:0000000000000000
>> [FAIL]  R10 has changed:0000000000000000
>> [FAIL]  R11 has changed:0000000000000000
>> [RUN]   Running tests under ptrace
>> not ok 1..1 selftests:  test_syscall_vdso_32 [FAIL]
>> make: Leaving directory '/usr/src/linux-selftests-x86_64-rhel-7.2-8bb2610bc4967f19672444a7b0407367f1540028/tools/testing/selftests/x86'
>>
>> This commit changed the testcase expected behavior, but looks it doesn't work as expected.
>> so want to consult whether 0Day missed something(special configurations) to this case ?
>>
>> if more details are needed, please let me know.
> Can you double-check that you're running the tests on an updated
> kernel?  The error you're getting makes it look like you've applied
> the patch to selftests but not to the kernel.


0Day always uses the same commit in selftests and kernel.
we first noticed this failure at v4.17-rc3, after bisecting, the FBC pointed to 8bb2610bc4967f19672444a7b0407367f1540028
so basing on v4.17-rc3, i reverted 8bb2610bc4967f19672444a7b0407367f1540028, then everything works well.

attached the kconfig.


Thanks



View attachment "config-4.17.0-rc3" of type "text/plain" (164178 bytes)