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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>,
	Christoph Hellwig <hch@infradead.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
	Anton Arapov <anton@redhat.com>,
	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.
Date: Thu, 8 Mar 2012 14:48:09 +0100	[thread overview]
Message-ID: <20120308134809.GB28488@elte.hu> (raw)
In-Reply-To: <20120308131824.GC13284@linux.vnet.ibm.com>


* Srikar Dronamraju <srikar@linux.vnet.ibm.com> wrote:

> @@ -233,9 +233,11 @@ static inline void __user *arch_compat_alloc_user_space(long len)
>  
>  	if (test_thread_flag(TIF_IA32)) {
>  		sp = task_pt_regs(current)->sp;
> +#ifdef CONFIG_X86_64
>  	} else {
>  		/* -128 for the x32 ABI redzone */
>  		sp = __this_cpu_read(old_rsp) - 128;
> +#endif
>  	}
>  
>  	return (void __user *)round_down(sp - len, 16);

So 'sp' is undefined if that TIF check fails?

Also, on a 32-bit kernel the TIF check probably fails all the 
time, because we don't set TIF_IA32 (and don't know that flag).

It would probably be better to make the whole helper inline 
#ifdef 64-bit, it does not look very useful on 32-bit.

Thanks,

	Ingo

  reply	other threads:[~2012-03-08 13:48 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-02-23 11:02 [PATCH] uprobes/core: handle breakpoint and signal step exception Srikar Dronamraju
2012-02-23 12:18 ` Anton Arapov
2012-02-24  5:31   ` Srikar Dronamraju
2012-02-27  9:12 ` Ingo Molnar
2012-02-28 13:26   ` Srikar Dronamraju
2012-02-28 13:52     ` Ingo Molnar
2012-02-28 14:17       ` Srikar Dronamraju
2012-02-28 14:27         ` Ingo Molnar
2012-03-08 13:18   ` Srikar Dronamraju
2012-03-08 13:48     ` Ingo Molnar [this message]
2012-03-09  6:28       ` Srikar Dronamraju
2012-03-09  7:33         ` Ingo Molnar
2012-03-13  5:20           ` Ingo Molnar
2012-03-13  5:42             ` Ingo Molnar
2012-03-13  5:47               ` Ingo Molnar
2012-03-13  9:24                 ` Srikar Dronamraju
2012-03-13  9:38                   ` Ingo Molnar
2012-02-27  9:24 ` Ingo Molnar

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