[lttng-dev] LTTng system call tracing on ARM

[Jan Glauber]

On Wed, Apr 10, 2013 at 12:20:12PM -0400, Mathieu Desnoyers wrote:
> 
> Thanks for the detailed report !!
> 
> Please try with this commit:

Yes, that patch works. But I'm still curious if you can explain what the
override was for ;-

--Jan
 
> commit 11fa478f18241fedee86f7dc7820a91c629c9e7e
> Author: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
> Date:   Wed Apr 10 12:14:38 2013 -0400
> 
>     Fix: remove ARM set_tls system call override
>     
>     We'll need to find a better way to instrument ARM-specific system calls
>     located at a far offset from the standard systems calls. A 16MB
>     lttng-modules kernel module is really not acceptable.
>     
>     Removing this instrumentation for now. sys_set_tls will appear as
>     sys_unknown.
>     
>     Fixes #472
>     
>     CC: Ryan Kyser <Ryan.Kyser at jci.com>
>     Ref: http://lists.lttng.org/pipermail/lttng-dev/2013-April/019990.html
>     Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
> 
> diff --git a/instrumentation/syscalls/headers/arm-32-syscalls-2.6.38_integers_override.h b/instrumentation/syscalls/headers/arm-32-syscalls-2.6.38_integers_override.h
> index 93b8674..895370f 100644
> --- a/instrumentation/syscalls/headers/arm-32-syscalls-2.6.38_integers_override.h
> +++ b/instrumentation/syscalls/headers/arm-32-syscalls-2.6.38_integers_override.h
> @@ -2,7 +2,6 @@
>  
>  #define OVERRIDE_TABLE_32_sys_arm_fadvise64_64
>  #define OVERRIDE_TABLE_32_sys_sync_file_range2
> -#define OVERRIDE_TABLE_32_sys_set_tls
>  
>  #ifndef CREATE_SYSCALL_TABLE
>  
> @@ -38,18 +37,6 @@ SC_TRACE_EVENT(sys_sync_file_range2,
>  	TP_printk()
>  )
>  
> -SC_TRACE_EVENT(sys_set_tls,
> -	TP_PROTO(unsigned int tid, unsigned long tls),
> -	TP_ARGS(tid, tls),
> -	TP_STRUCT__entry(
> -		__field(unsigned int, tid)
> -		__field_hex(unsigned int, tls)),
> -	TP_fast_assign(
> -		tp_assign(tid, tid)
> -		tp_assign(tls, tls)),
> -	TP_printk()
> -)
> -
>  #else	/* CREATE_SYSCALL_TABLE */
>  
>  #define OVVERRIDE_TABLE_32_sys_mmap
> @@ -59,9 +46,6 @@ TRACE_SYSCALL_TABLE(sys_mmap, sys_mmap, 90, 6)
>  TRACE_SYSCALL_TABLE(sys_arm_fadvise64_64, sys_arm_fadvise64_64, 270, 4)
>  #define OVERRIDE_TABLE_32_sys_sync_file_range2
>  TRACE_SYSCALL_TABLE(sys_sync_file_range2, sys_sync_file_range2, 341, 4)
> -#define OVERRIDE_TABLE_32_sys_set_tls
> -TRACE_SYSCALL_TABLE(sys_set_tls, sys_set_tls, 0xf0005, 2)
> -
>  
>  #endif /* CREATE_SYSCALL_TABLE */
>  
> 
> 
> > 
> > --Jan
> > 
> > > -PL
> > > 
> > > 
> > > 
> > > On Wed, Apr 10, 2013 at 9:02 AM, Jan Glauber <jan.glauber at gmail.com> wrote:
> > > 
> > > > On Wed, Apr 10, 2013 at 08:37:18AM -0400, PLSTC wrote:
> > > > > Hey Jan,
> > > > >
> > > > > I cannot speak on behalf of everyone here, but during our attempt to port
> > > > > LTTng to Android, we also noticed that the kernels we were using (3.0.x)
> > > > > were nowhere near the requirements for syscall tracepoints support. I
> > > > > believe such support was added on x86/64 way earlier (early 3.x) than on
> > > > > ARM, which is why it was included in LTTng's modules a while ago. Simply
> > > > > put, the ARM kernel is late.
> > > >
> > > > OK, so for ARM kernel version 3.6 is the minimum unless the syscall
> > > > tracepoint
> > > > support is backported.
> > > >
> > > > > There are a few actuals ways to 'enable' syscall tracepoints support on
> > > > > early ARM kernels, but they all including a bit of kernel
> > > > hacking/patching.
> > > > > I could send you some links if you're interested in that.
> > > >
> > > > Yes, sure!
> > > >
> > > > --Jan
> > > >
> > > > > -PL
> > > > > On Apr 10, 2013 4:40 AM, "Jan Glauber" <jan.glauber at gmail.com> wrote:
> > > > >
> > > > > > Hi,
> > > > > >
> > > > > > I want to use LTTng for system call tracing on ARM. Now lttng-modules
> > > > seems
> > > > > > to support system call tracing on ARM already since
> > > > > > "8f4f80e LTTng Modules ARM syscall instrumentation".
> > > > > >
> > > > > > But I wonder how that worked since lttng-syscalls.c is only build under
> > > > > > CONFIG_HAVE_SYSCALL_TRACEPOINTS and that was added to ARM only with
> > > > kernel
> > > > > > 3.6
> > > > > > (much after than the lttng-modules commit).
> > > > > >
> > > > > > Am I missing something? Is system call tracing working on ARM with the
> > > > > > upstream
> > > > > > LTTng version?
> > > > > >
> > > > > > thanks,
> > > > > > Jan
> > > > > >
> > > > > > _______________________________________________
> > > > > > lttng-dev mailing list
> > > > > > lttng-dev at lists.lttng.org
> > > > > > http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
> > > > > >
> > > >
> > 
> > _______________________________________________
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> > lttng-dev at lists.lttng.org
> > http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
> 
> -- 
> Mathieu Desnoyers
> EfficiOS Inc.
> http://www.efficios.com