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Date: Tue, 13 Mar 2012 06:42:42 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>, Peter Zijlstra <peterz@infradead.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Oleg Nesterov <oleg@redhat.com>, LKML <linux-kernel@vger.kernel.org>,
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        Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
        Jim Keniston <jkenisto@linux.vnet.ibm.com>,
        Jiri Olsa <jolsa@redhat.com>, Josh Stone <jistone@redhat.com>
Subject: Re: [PATCH] uprobes/core: handle breakpoint and signal step
 exception.
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* Ingo Molnar <mingo@elte.hu> wrote:

> I.e. you could drop this patch altogether:
> 
>   x86/trivial: Fix 'old_rsp' undefined build failure when including asm/compat.h
> 
> And rework the is_ia32_compat_task() patch to use another 
> header and to use the is_32bit_task() name. Also, you should 
> double check whether the x32 execution model needs special 
> consideration as well:
> 
>  #define TIF_IA32		17	/* IA32 compatibility process */
>  #define TIF_X32		30	/* 32-bit native x86-64 binary */
> 
> otherwise uprobe will not work with x32 tasks properly.

Given that x32 tasks are using native 64-bit syscalls, what you 
need is the is_ia32_task() check. We have that in -tip already, 
in compat.h. If uprobes uses that definition then uprobes will 
be able to probe x32 tasks as well.

To make it available to uprobes please move is_ia32_task() to 
processor.h and make it return 1 on i386 kernels. This should be 
a very simple patch - and that's all that is needed.

Thanks,

	Ingo