Status of ARM user-space support?

Status of ARM user-space support?

[Grant Edwards]

What's the current state of user-space support for ARM?

A while back I remember finding a blog or mailing list post mentioning
that kernel patches had been submitted upstream to enable ARM user-space
support.  But, I can't seem to find that post/thread now...

-- 
Grant Edwards               grant.b.edwards        Yow! !  Everybody out of
                                  at               the GENETIC POOL!
                              gmail.com            

Re: Status of ARM user-space support?

[Frank Ch. Eigler]

Grant Edwards <grant.b.edwards@gmail.com> writes:

> What's the current state of user-space support for ARM? [...]

Unfortunately, I am not aware of any current efforts to port
any uprobes version to ARM.

- FChE

Re: Status of ARM user-space support?

[Grant Edwards]

On 2010-10-26, Frank Ch. Eigler <fche@redhat.com> wrote:
>
> Grant Edwards <grant.b.edwards@gmail.com> writes:
>
>> What's the current state of user-space support for ARM? [...]
>
> Unfortunately, I am not aware of any current efforts to port
> any uprobes version to ARM.

I finally found the posting I remembered reading.  Did I misunderstand?

  http://thread.gmane.org/gmane.linux.systemtap/12105/focus=12108


         >   - get arm and mips converted to regsets and uprobes, set a
         >     cut off date for others (Christoph, Roland)

         >  *** Update 4/24/09: arm work finished by Roland. (posted to
         >  lkml?) Christoph pinged the mips maintainer, no reply seen.

         The arm work was posted upstream on 4/24, but there have been
         no replies from ARM folks. [...]

I read that to mean that uprobes was done for the ARM and it just
needed to be incorporated into the mainline kernel sources by the
maintainers.  If so, are those patches available somewhere?

-- 
Grant Edwards               grant.b.edwards        Yow! I want a VEGETARIAN
                                  at               BURRITO to go ... with
                              gmail.com            EXTRA MSG!!

Re: Status of ARM user-space support?

[Roland McGrath]

>          >  *** Update 4/24/09: arm work finished by Roland. (posted to
>          >  lkml?) Christoph pinged the mips maintainer, no reply seen.
> 
>          The arm work was posted upstream on 4/24, but there have been
>          no replies from ARM folks. [...]

This refers to the work I did, which is only user_regset, tracehook, and
asm/syscall.h cleanups for ARM.  None of that went in, though not for any
particular reason.  Since then someone did something about asm/syscall.h
IIRC, but nobody has ever paid enough attention to merge the user_regset
and tracehook work I did.  That stuff is internal kernel cleanups that
don't by itself give you any exciting new features (only some core-dump
support for the arcane register flavors that lacked them).  

I have never done any work related to ARM support for instruction-copying
breakpoint insertion, which is the crux of kprobes and uprobes.  I'm not
aware of what others may have done in those areas.


Thanks,
Roland

Re: Status of ARM user-space support?

[Grant Edwards]

On 2010-10-26, Roland McGrath <roland@redhat.com> wrote:
>>          >  *** Update 4/24/09: arm work finished by Roland. (posted to
>>          >  lkml?) Christoph pinged the mips maintainer, no reply seen.
>> 
>>          The arm work was posted upstream on 4/24, but there have been
>>          no replies from ARM folks. [...]
>
> This refers to the work I did, which is only user_regset, tracehook, and
> asm/syscall.h cleanups for ARM.  None of that went in, though not for any
> particular reason.  Since then someone did something about asm/syscall.h
> IIRC, but nobody has ever paid enough attention to merge the user_regset
> and tracehook work I did.  That stuff is internal kernel cleanups that
> don't by itself give you any exciting new features (only some core-dump
> support for the arcane register flavors that lacked them).  
>
> I have never done any work related to ARM support for instruction-copying
> breakpoint insertion, which is the crux of kprobes and uprobes.  I'm not
> aware of what others may have done in those areas.

Rats.

When it said "arm work finished" after the bullet item "get arm and
mips converted to regsets and uprobes", I thought that meant that the
arm work was finished for regsets and uprobes.

There'll be some back-pedalling in the next project status meeting...

-- 
Grant Edwards               grant.b.edwards        Yow! But they went to MARS
                                  at               around 1953!!
                              gmail.com            

Re: Status of ARM user-space support?

[Frank Ch. Eigler]

Grant Edwards <grant.b.edwards@gmail.com> writes:

> [...]
>>>          The arm work was posted upstream on 4/24, but there have been
>>>          no replies from ARM folks. [...]
> [...]
> When it said "arm work finished" after the bullet item "get arm and
> mips converted to regsets and uprobes", I thought that meant that the
> arm work was finished for regsets and uprobes.

Yeah.  Roland's work has enabled ARM utrace (not uprobes), but for
whatever reason hasn't been merged yet.  ezannoni erred in mentioning
uprobes.  It would be nice if someone providing ARM distro and
interested in systemtap were to get in touch to fill in the missing
bits.

- FChE

Re: Status of ARM user-space support?

[Jim Keniston]

On Tue, 2010-10-26 at 22:28 -0400, Frank Ch. Eigler wrote:
> Grant Edwards <grant.b.edwards@gmail.com> writes:
> 
> > [...]
> >>>          The arm work was posted upstream on 4/24, but there have been
> >>>          no replies from ARM folks. [...]
> > [...]
> > When it said "arm work finished" after the bullet item "get arm and
> > mips converted to regsets and uprobes", I thought that meant that the
> > arm work was finished for regsets and uprobes.
> 
> Yeah.  Roland's work has enabled ARM utrace (not uprobes), but for
> whatever reason hasn't been merged yet.  ezannoni erred in mentioning
> uprobes.  It would be nice if someone providing ARM distro and
> interested in systemtap were to get in touch to fill in the missing
> bits.
> 
> - FChE

Yes.  Neither uprobes nor utrace is upstream.  The version of uprobes
that ships with SystemTap requires utrace.  I can email you our uprobes
porting guide, Grant, but of course it's not much use if your ARM system
doesn't include utrace.

Jim Keniston