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Subject: Re: [RFC] [PATCH 2.6.37-rc5-tip 13/20] 13: x86: x86 specific probe
 handling
From: Peter Zijlstra <peterz@infradead.org>
To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>,
        Arnaldo Carvalho de Melo <acme@infradead.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
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        Jim Keniston <jkenisto@linux.vnet.ibm.com>,
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Date: Tue, 25 Jan 2011 14:56:22 +0100
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On Thu, 2010-12-16 at 15:29 +0530, Srikar Dronamraju wrote:
> 
> +void arch_uprobe_enable_sstep(struct pt_regs *regs)
> +{
> +       /*
> +        * Enable single-stepping by
> +        * - Set TF on stack
> +        * - Set TIF_SINGLESTEP: Guarantees that TF is set when
> +        *      returning to user mode.
> +        *  - Indicate that TF is set by us.
> +        */
> +       regs->flags |= X86_EFLAGS_TF;
> +       set_thread_flag(TIF_SINGLESTEP);
> +       set_thread_flag(TIF_FORCED_TF);
> +}
> +
> +void arch_uprobe_disable_sstep(struct pt_regs *regs)
> +{
> +       /* Disable single-stepping by clearing what we set */
> +       clear_thread_flag(TIF_SINGLESTEP);
> +       clear_thread_flag(TIF_FORCED_TF);
> +       regs->flags &= ~X86_EFLAGS_TF;
> +} 

Why not use the code from arch/x86/kernel/step.c?