rseq system call incompletely wired up in microblaze

rseq system call incompletely wired up in microblaze

[Mathieu Desnoyers]

Hi Michal,

I notice the following commit went into 4.18:

commit 54b0a2011dfcd2e3fe2c28062694fbbe3eb377a3
Author: Michal Simek <michal.simek@xilinx.com>
Date:   Thu Jun 14 08:24:39 2018 +0200

    microblaze: Add new syscalls io_pgetevents and rseq
    
    Wire up new syscalls io_pgetevents and rseq.
    
    Signed-off-by: Michal Simek <michal.simek@xilinx.com>

It adds the rseq system call to the microblaze syscall list, but
does not add the required hooks in the architecture code, nor does
it select HAVE_RSEQ. So effectively, even though sys_rseq is reserved
on microblaze, it currently always returns ENOSYS.

Is your intent to simply reserve the system call number, or to
also get rseq to work on microblaze ?

A good example of the architecture changes required to
wire up rseq can be found here:

commit 9d6d99e3ac8ccfd0945edb3c83cd912838775056
Author: Heiko Carstens <heiko.carstens@de.ibm.com>
Date:   Sat Jun 30 10:54:15 2018 +0200

    s390: wire up rseq system call
    
    Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
    Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

Also, please make sure the tools/testing/selftests/rseq/ tests
pass before pushing a commit enabling it for your architecture.

Thanks,

Mathieu

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com

Re: rseq system call incompletely wired up in microblaze

[Michal Simek]

Hi Mathieu,

On 14.10.2018 18:46, Mathieu Desnoyers wrote:
> Hi Michal,
> 
> I notice the following commit went into 4.18:
> 
> commit 54b0a2011dfcd2e3fe2c28062694fbbe3eb377a3
> Author: Michal Simek <michal.simek@xilinx.com>
> Date:   Thu Jun 14 08:24:39 2018 +0200
> 
>     microblaze: Add new syscalls io_pgetevents and rseq
>     
>     Wire up new syscalls io_pgetevents and rseq.
>     
>     Signed-off-by: Michal Simek <michal.simek@xilinx.com>
> 
> It adds the rseq system call to the microblaze syscall list, but
> does not add the required hooks in the architecture code, nor does
> it select HAVE_RSEQ. So effectively, even though sys_rseq is reserved
> on microblaze, it currently always returns ENOSYS.
> 
> Is your intent to simply reserve the system call number, or to
> also get rseq to work on microblaze ?

Yes. my indentation is allocate syscall numbers for all these new
syscalls because it takes some time when new syscalls numbers are
propagated to toolchain builds.
I can't see a problem if ENOSYS is returned because it is proper
reaction when syscall is not implemented.

Thanks,
Michal