Subject: Re: [PATCH 1/2] powerpc: ptrace CHECK_FULL_REGS
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Roland McGrath <roland@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>, linuxppc-dev@ozlabs.org,
       David Woodhouse <dwmw2@redhat.com>,
       Andrew Morton <akpm@linux-foundation.org>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       linux-kernel@vger.kernel.org
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Date: Tue, 25 Sep 2007 13:58:46 +1000
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On Mon, 2007-09-24 at 17:59 -0700, Roland McGrath wrote:
> > Yup, I think I ditched most of them.. for some reason I decided it
> > couldn't happen, but maybe I'm wrong ?
> 
> Well, it's a BUG_ON.  It's supposed to be for something that "can't happen".
> That's why it's a sanity check, not a wild assertion. ;-)
> 
> The 2/2 patch is an example of a bug that CHECK_FULL_REGS catches.
> In the status quo, using PTRACE_PEEKUSR in a bug case crashes while using
> PTRACE_GETREGS in the same place might get bogus data.  (In the actual bug
> thus found, the data is not bogus and only the bit that FULL_REGS checks is.)

Fair enough.

Ben.


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