From: Michael Neuling <mikey@neuling•org>
To: Benjamin Herrenschmidt <benh@kernel•crashing.org>
Cc: linuxppc-dev@lists•ozlabs.org, Matt Evans <matt@ozlabs•org>
Subject: Re: [PATCH 2/5] powerpc/tm: Fix 32 bit non-rt signals
Date: Sun, 09 Jun 2013 20:12:29 +1000 [thread overview]
Message-ID: <24241.1370772749@ale.ozlabs.ibm.com> (raw)
In-Reply-To: <1370762745.14883.11.camel@pasglop>
Benjamin Herrenschmidt <benh@kernel•crashing.org> wrote:
> On Fri, 2013-06-07 at 20:36 +1000, Michael Neuling wrote:
> > Currently sys_sigreturn() is TM unaware. Therefore, if we take a 32 bit signal
> > without SIGINFO (non RT) inside a transaction, on signal return we don't
> > restore the signal frame correctly.
> >
> > This checks if the signal frame being restoring is an active transaction, and
> > if so, it copies the additional state to ptregs so it can be restored.
> >
> > Signed-off-by: Michael Neuling <mikey@neuling•org>
> > ---
>
> .../...
>
> > +#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
> > + mcp = (struct mcontext __user *)&sf->mctx;
> > + tm_mcp = (struct mcontext __user *)&sf->mctx_transact;
> > + if (__get_user(msr_hi, &tm_mcp->mc_gregs[PT_MSR]))
> > goto badframe;
> > + if MSR_TM_ACTIVE(msr_hi<<32) {
>
> Mising ( and ). I'll apply that fix locally.
>
> Appart from that, I suppose it's ok. I don't see any exposure
> coming from users "cooking" the tm_frame and calling sigreturn,
> so as long as we are confident userspace generally only uses
> sigreturn with frames it got from an actual signal, and doesn't
> try to "generate" frames by hand, we should be ok.
We should add a has_cpu_feature(TM) here also in case someone cooks up
an sig frame with MSR TM active, but on a non TM CPU. This could possibly
result in a trecheckpoint on a non TM CPU hence an illegal in the
kernel.
I'll repost.
Thanks,
Mikey
next prev parent reply other threads:[~2013-06-09 10:12 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-07 10:36 [PATCH 1/5] powerpc/tm: Fix writing top half of MSR on 32 bit signals Michael Neuling
2013-06-07 10:36 ` [PATCH 2/5] powerpc/tm: Fix 32 bit non-rt signals Michael Neuling
2013-06-09 7:25 ` Benjamin Herrenschmidt
2013-06-09 10:12 ` Michael Neuling [this message]
2013-06-07 10:36 ` [PATCH 3/5] powerpc/tm: Fix restoration of MSR on 32bit signal return Michael Neuling
2013-06-09 7:27 ` Benjamin Herrenschmidt
2013-06-09 9:56 ` Michael Neuling
2013-06-07 10:36 ` [PATCH 4/5] powerpc/tm: Fix return of 32bit rt signals to active transactions Michael Neuling
2013-06-07 10:36 ` [PATCH 5/5] powerpc/tm: Fix return of active 64bit signals Michael Neuling
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