Re: [LTP] [PATCH] syscalls: fix some failure on arch X86_64

Wei Yongjun
2009-11-11T05:06:30Z

Mike Frysinger wrote:
> On Tuesday 10 November 2009 04:38:30 liubo wrote:
>
>> 1) rt_sigaction
>> "sigaction" has the structure:
>>
>> struct sigaction {
>> __sighandler_t sa_handler;
>> unsigned long sa_flags;
>> #ifdef SA_RESTORER
>> __sigrestore_t sa_restorer;
>> #endif
>> sigset_t sa_mask; /* mask last for extensibility */
>> };
>>
>> However, on arch x86_64, if we directly get to call rt_sigaction,
>> the argument "sa_restorer" will not be fulfilled, and this will lead
>> to segment fault.
>> on arch x86_64, if sa_restorer is not set, kernel will lead to segment
>> fault. In other arch, if sa_restorer is not set, kernel can do the correct
>> work. To avoid this segment fault, we use glibc function
>> "int sigaction(...);" instead, which can fulfill the argument
>> "sa_restorer".
>>
>
> which defeats the purpose of the test. there is no guarantee that the C
> library sigaction function is implemented via the __NR_rt_sigaction syscall.
>

In x86_64, it do this. And If we want to use __NR_rt_sigaction syscall
directly, we must fill the sa_restorer and set the RESTORER flag to
sa_mask. If we do not set the sa_restorer, kill will always cause
segment fault.

>
>> 2) rt_sigprocmask
>> This failure contains two aspects,
>> the first is the segment fault as described in 1),
>> the second is that testcase uses a unknown signal 33 for test,
>> and this will lead sigaction cannot bind signal 33 to the action.
>>
>> So, we attempt to use a known signal instead, such as 34.
>>
>
> which is just as bogus and unportable. if the test needs a real time signal,
> it should leverage the sigrtmin...sigrtmax defines.
> -mike
>
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