From: Roland McGrath <roland@redhat.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Woodhouse <dwmw2@redhat.com>,
linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org,
Paul Mackerras <paulus@samba.org>,
Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 1/2] powerpc: ptrace CHECK_FULL_REGS
Date: Mon, 24 Sep 2007 17:59:44 -0700 (PDT) [thread overview]
Message-ID: <20070925005945.02E924D04B7@magilla.localdomain> (raw)
In-Reply-To: Benjamin Herrenschmidt's message of Tuesday, 25 September 2007 10:33:26 +1000 <1190680406.12382.9.camel@localhost.localdomain>
> 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.)
Thanks,
Roland
next prev parent reply other threads:[~2007-09-25 0:59 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-09-24 23:50 [PATCH 1/2] powerpc: ptrace CHECK_FULL_REGS Roland McGrath
2007-09-25 0:33 ` Benjamin Herrenschmidt
2007-09-25 0:59 ` Roland McGrath [this message]
2007-09-25 3:58 ` Benjamin Herrenschmidt
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