Re: [PATCH 4/6] tracing: add tracing support for compat syscalls

[Heiko Carstens <heiko.carstens@de.ibm.com>]

On Mon, Feb 08, 2010 at 10:43:25AM -0500, Jason Baron wrote:
> On Wed, Feb 03, 2010 at 01:52:51PM +0100, Heiko Carstens wrote:
> > On Tue, Feb 02, 2010 at 04:21:51PM -0500, Jason Baron wrote:
> > > Add core support to event tracing for compat syscalls. The basic idea is that we
> > > check if we have a compat task via 'is_compat_task()'. If so, we lookup in the
> > > new compat_syscalls_metadata table, the corresponding struct syscall_metadata, to
> > > check syscall arguments and whether or not we are enabled.
> > > 
> > > Signed-off-by: Jason Baron <jbaron@redhat.com>
> > > ---
> > >  include/linux/compat.h        |    8 +++++
> > >  include/trace/syscall.h       |    4 ++
> > >  kernel/trace/trace.h          |    2 +
> > >  kernel/trace/trace_syscalls.c |   63 +++++++++++++++++++++++++++++++++++-----
> > >  4 files changed, 69 insertions(+), 8 deletions(-)
> > > 
> > > diff --git a/include/linux/compat.h b/include/linux/compat.h
> > > index ef68119..ab2cda2 100644
> > > --- a/include/linux/compat.h
> > > +++ b/include/linux/compat.h
> > > @@ -353,5 +353,13 @@ asmlinkage long compat_sys_newfstatat(unsigned int dfd, char __user * filename,
> > >  asmlinkage long compat_sys_openat(unsigned int dfd, const char __user *filename,
> > >  				  int flags, int mode);
> > > 
> > > +#else /* CONFIG_COMPAT */
> > > +
> > > +#define NR_syscalls_compat 0
> > > +static inline int is_compat_task(void)
> > > +{
> > > +	return 0;
> > > +}
> > > +
> > >  #endif /* CONFIG_COMPAT */
> > >  #endif /* _LINUX_COMPAT_H */
> > 
> > This part will break compilation on s390, since it has already the same
> > function defined for !CONFIG_COMPAT.
> 
> If multiple arches want this definition, then it seems the the common
> include/linux/compat.h is good place for it.
> 
> > In order to avoid the whole ifdef mess some s390 files do include
> > asm/compat.h instead of linux/compat.h. This will get messy :)
> 
> is there a way for s390 to use the common include/linux/compat.h file?
> what other arch defs are required? 

Yes of course it is possible (I think :). I'll send a patch.