On 2018/6/7 1:48, h...@zytor.com wrote:
> On June 6, 2018 2:17:42 AM PDT, "Leizhen (ThunderTown)"
> <thunder.leiz...@huawei.com> wrote:
>> I found that glibc has already dealt with this case. So this issue must
>> have been met before, should it be maintained by libc/user?
>>
>> if (GLRO(dl_sysinfo_dso) == NULL)
>> {
>> kact.sa_flags |= SA_RESTORER;
>>
>> kact.sa_restorer = ((act->sa_flags & SA_SIGINFO)
>> ? &restore_rt : &restore);
>> }
>>
>>
>> On 2018/6/6 15:52, Leizhen (ThunderTown) wrote:
>>>
>>>
>>> On 2018/6/5 19:24, Leizhen (ThunderTown) wrote:
>>>> After I executed "echo 0 > /proc/sys/abi/vsyscall32" to disable
>> vdso, the rt_sigaction01 test case from ltp_2015 failed.
>>>> The test case source code please refer to the attachment, and the
>> output as blow:
>>>>
>>>> -----------------
>>>> ./rt_sigaction01
>>>> rt_sigaction01 0 TINFO : signal: 34
>>>> rt_sigaction01 1 TPASS : rt_sigaction call succeeded: result =
>> 0
>>>> rt_sigaction01 0 TINFO : sa.sa_flags = SA_RESETHAND|SA_SIGINFO
>>>> rt_sigaction01 0 TINFO : Signal Handler Called with signal
>> number 34
>>>>
>>>> Segmentation fault
>>>> ------------------
>>>>
>>>>
>>>> Is this the desired result? In function ia32_setup_rt_frame, I found
>> below code:
>>>>
>>>> if (ksig->ka.sa.sa_flags & SA_RESTORER)
>>>> restorer = ksig->ka.sa.sa_restorer;
>>>> else
>>>> restorer = current->mm->context.vdso +
>>>> vdso_image_32.sym___kernel_rt_sigreturn;
>>>> put_user_ex(ptr_to_compat(restorer), &frame->pretcode);
>>>>
>>>> Because the vdso is disabled, so current->mm->context.vdso is NULL,
>> which cause the result of frame->pretcode invalid.
>>>>
>>>> I'm not sure whether this is a kernel bug or just an error of test
>> case itself. Can anyone help me?
>>>>
>>>
>
> The use of signals without SA_RESTORER is considered obsolete, but it's
> somewhat surprising that the vdso isn't there; it should be mapped even for
> static binaries esp. on i386 since it is the preferred way to do system calls
> (you don't need to parse the ELF for that.) Are you explicitly disabling the
> VDSO? If so, Don't Do That.
Yes, the vdso was explicitly disabled by the tester. Thanks.
>
--
Thanks!
BestRegards
