[LTP] [PATCH] stime: Only o32 system calls require 32-bit programs on mips

[zhanglianjie]

On 2021-07-20 17:40, Petr Vorel wrote:
> Hi zhanglianjie,
> 
> [ Cc Thomas Bogendoerfer, MIPS kernel maintainer ]
> 
>> On 2021-07-20 15:56, Petr Vorel wrote:
>>> Hi zhanglianjie,
> 
>>>> The stime() system call is only o32, not n32 and n64. If you do not
>>>> specify that the current program is compiled to 32-bit when compiling
>>>> the program on mips, the stime() system call will fail when the
>>>> program is running.
>>> You're right that stime() is only on o32. But tst_syscall() should catch that.
>>> Or does it set different errno than ENOSYS?
> 
>> The returned errno is EFAULT. The o32 system call of stime is implemented on
>> mips, so ENOSYS will not be returned.
> I see.
> 
>> COMPAT_SYSCALL_DEFINE1(stime, compat_time_t __user *, tptr)
>> {
>>      ...
>>      if (get_user(tv.tv_sec, tptr))
>>          return -EFAULT;
>>      ...
>> }
> 
>> The tptr address is in the user space 0x120010da0, and after the system
>> call, it is 0x20010da0 in the kernel state, and the upper 32 bits are set to
>> 0, resulting in a failure to copy data from the user space to the kernel
>> space.
> Thanks for explanation.
> 
>> This patch needs to be modified and cannot affect other architectures.
> Yes, o2 has to fixed, but agree that this would affect other archs which
> supports __NR_stime, i.e. i386 now also complains:
> stime_var.h:31: TCONF: the stime() syscall only o32 ABI in mips, make sure the current program is 32-bit
> 
> but it should stay:
> stime02.c:37: TPASS: stime(2) fails, Caller not root: EPERM (1)
> 
Thanks for the code review.
If it only affects the mips architecture and does not affect other 
architectures, does it need to be modified here?
>>> ...
>>>> +#if defined(__mips__) && _MIPS_SZLONG == 32
> Not sure if this would work to whitelist only mips n32 and n64 (keep mips o32
> and all other archs):
> #if ! defined(_MIPS_SZLONG) || _MIPS_SZLONG == 32
> 
It can be determined that only mips n32 and n64 need to be whitelisted, 
and calling stime() on other 64-bit architectures will return ENOSYS.

In the following compilation conditions, _ABIO32, _ABI64, and _ABIN32 
have been defined:

grep -E 'ifdef|if defined' ~/ltp/include/lapi/syscalls.h
#ifdef __aarch64__
#ifdef __arc__
#ifdef __arm__
#ifdef __hppa__
#ifdef __i386__
#ifdef __ia64__
#if defined(__mips__) && defined(_ABIN32)
#if defined(__mips__) && defined(_ABI64)
#if defined(__mips__) && defined(_ABIO32)
#ifdef __powerpc64__
#ifdef __powerpc__
#ifdef __s390x__
#if defined(__s390__) && !defined(__s390x__)
#ifdef __sh__
#if defined(__sparc__) && defined(__arch64__)
#if defined(__sparc__) && !defined(__arch64__)
#ifdef __x86_64__


Modified patch v2:
https://patchwork.ozlabs.org/project/ltp/patch/20210720083708.13281-1-zhanglianjie@uniontech.com/
> 
>>>>    		return tst_syscall(__NR_stime, ntime);
>>>> +#else
>>>> +		tst_brk(TCONF, "the stime() syscall only o32 ABI in mips, make sure the current program is 32-bit");
>>>> +#endif
> 

-- 
Regards,
Zhang Lianjie