From: Michael Ellerman <mpe@ellerman.id.au>
To: Peter Zijlstra <peterz@infradead.org>,
Christoph Hellwig <hch@infradead.org>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
"Christopher M. Riedl" <cmr@codefail.de>
Subject: Re: [PATCH 3/8] powerpc: Mark functions called inside uaccess blocks w/ 'notrace'
Date: Tue, 20 Oct 2020 18:34:06 +1100 [thread overview]
Message-ID: <87v9f5xsep.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <20201016094132.GI2611@hirez.programming.kicks-ass.net>
Peter Zijlstra <peterz@infradead.org> writes:
> On Fri, Oct 16, 2020 at 07:56:16AM +0100, Christoph Hellwig wrote:
>> On Thu, Oct 15, 2020 at 10:01:54AM -0500, Christopher M. Riedl wrote:
>> > Functions called between user_*_access_begin() and user_*_access_end()
>> > should be either inlined or marked 'notrace' to prevent leaving
>> > userspace access exposed. Mark any such functions relevant to signal
>> > handling so that subsequent patches can call them inside uaccess blocks.
>>
>> I don't think running this much code with uaccess enabled is a good
>> idea. Please refactor the code to reduce the criticial sections with
>> uaccess enabled.
>>
>> Btw, does powerpc already have the objtool validation that we don't
>> accidentally jump out of unsafe uaccess critical sections?
>
> It does not, there was some effort on that a while ago, but I suspect
> they're waiting for the ARM64 effort to land and build on that.
Right, we don't have objtool support.
We would definitely like objtool support at least for this uaccess
checking, I'm sure we have some escapes.
There was someone working on it in their own-time but last I heard that
was still WIP.
I didn't realise the ARM64 support was still not merged, so yeah having
that land first would probably simplify things, but we still need
someone who has time to work on it.
cheers
next prev parent reply other threads:[~2020-10-20 7:36 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-15 15:01 [PATCH 0/8] Improve signal performance on PPC64 with KUAP Christopher M. Riedl
2020-10-15 15:01 ` [PATCH 1/8] powerpc/uaccess: Add unsafe_copy_from_user Christopher M. Riedl
2020-10-16 6:54 ` Christoph Hellwig
2020-10-16 13:18 ` Christophe Leroy
2020-10-16 13:17 ` Christophe Leroy
2020-10-20 3:00 ` Christopher M. Riedl
2020-10-15 15:01 ` [PATCH 2/8] powerpc/signal: Add unsafe_copy_{vsx,fpr}_from_user() Christopher M. Riedl
2020-10-16 13:48 ` [PATCH 2/8] powerpc/signal: Add unsafe_copy_{vsx, fpr}_from_user() Christophe Leroy
2020-10-20 2:01 ` [PATCH 2/8] powerpc/signal: Add unsafe_copy_{vsx,fpr}_from_user() Christopher M. Riedl
2021-02-06 16:32 ` [PATCH 2/8] powerpc/signal: Add unsafe_copy_{vsx, fpr}_from_user() Christophe Leroy
2021-02-06 17:39 ` [PATCH 2/8] powerpc/signal: Add unsafe_copy_{vsx,fpr}_from_user() Christopher M. Riedl
2021-02-07 10:12 ` [PATCH 2/8] powerpc/signal: Add unsafe_copy_{vsx, fpr}_from_user() Christophe Leroy
2021-02-08 17:14 ` [PATCH 2/8] powerpc/signal: Add unsafe_copy_{vsx,fpr}_from_user() Christopher M. Riedl
2021-02-08 17:18 ` [PATCH 2/8] powerpc/signal: Add unsafe_copy_{vsx, fpr}_from_user() Christophe Leroy
2020-10-15 15:01 ` [PATCH 3/8] powerpc: Mark functions called inside uaccess blocks w/ 'notrace' Christopher M. Riedl
2020-10-16 6:56 ` Christoph Hellwig
2020-10-16 9:41 ` Peter Zijlstra
2020-10-20 7:34 ` Michael Ellerman [this message]
2020-10-16 7:02 ` Christophe Leroy
2020-10-20 1:59 ` Christopher M. Riedl
2020-10-15 15:01 ` [PATCH 4/8] powerpc/signal64: Replace setup_sigcontext() w/ unsafe_setup_sigcontext() Christopher M. Riedl
2020-10-15 15:01 ` [PATCH 5/8] powerpc/signal64: Replace restore_sigcontext() w/ unsafe_restore_sigcontext() Christopher M. Riedl
2020-10-15 15:01 ` [PATCH 6/8] powerpc/signal64: Replace setup_trampoline() w/ unsafe_setup_trampoline() Christopher M. Riedl
2020-10-16 13:56 ` Christophe Leroy
2020-10-20 2:42 ` Christopher M. Riedl
2020-10-20 5:02 ` Christophe Leroy
2020-10-15 15:01 ` [PATCH 7/8] powerpc/signal64: Rewrite handle_rt_signal64() to minimise uaccess switches Christopher M. Riedl
2020-10-16 14:00 ` Christophe Leroy
2020-10-20 2:44 ` Christopher M. Riedl
2020-10-15 15:01 ` [PATCH 8/8] powerpc/signal64: Rewrite rt_sigreturn() " Christopher M. Riedl
2020-10-16 14:07 ` Christophe Leroy
2020-10-20 2:45 ` Christopher M. Riedl
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