Christian Brauner <christian@xxxxxxxxxx> writes:
> On Fri, Jul 19, 2019 at 08:18:02PM +1000, Michael Ellerman wrote:
>> Christian Brauner <christian@xxxxxxxxxx> writes:
>> > On Mon, Jul 15, 2019 at 03:56:04PM +0200, Christian Borntraeger wrote:
>> >> I think Vasily already has a clone3 patch for s390x with 435.
>> >
>> > A quick follow-up on this. Helge and Michael have asked whether there
>> > are any tests for clone3. Yes, there will be and I try to have them
>> > ready by the end of the this or next week for review. In the meantime I
>> > hope the following minimalistic test program that just verifies very
>> > very basic functionality (It's not pretty.) will help you test:
>>
>> Hi Christian,
>>
>> Thanks for the test.
>>
>> This actually oopses on powerpc, it hits the BUG_ON in CHECK_FULL_REGS
>> in process.c around line 1633:
>>
>> } else {
>> /* user thread */
>> struct pt_regs *regs = current_pt_regs();
>> CHECK_FULL_REGS(regs);
>> *childregs = *regs;
>> if (usp)
>>
>>
>> So I'll have to dig into how we fix that before we wire up clone3.
>>
>> Turns out testing is good! :)
>
> Indeed. I have a test-suite for clone3 in mind and I hope to have it
> ready by the end of next week. It's just always the finding the time
> part that is annoying. :)
I know the feeling!
> Thanks for digging into this, Michael!
No worries, happy to help where I can.
In the intervening five minutes I remembered how we handle this, we just
need a little wrapper to save the non-volatile regs:
_GLOBAL(ppc_clone3)
bl save_nvgprs
bl sys_clone3
b .Lsyscall_exit
A while back I meant to make it generate those automatically based on a
flag in the syscall.tbl but of course haven't got around to it :)
So with the above it seems all good:
$ ./clone3 ; echo $?
Parent process received child's pid 4204 as return value
Parent process received child's pidfd 3
Parent process received child's pid 4204 as return argument
Child process with pid 4204
0
I'll send a patch to wire it up on Monday.
cheers
