From: Will Deacon <will@kernel.org>
To: Kees Cook <keescook@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>, Jann Horn <jannh@google.com>,
Peter Zijlstra <peterz@infradead.org>,
Catalin Marinas <catalin.marinas@arm.com>,
linux-kernel@vger.kernel.org, Mark Rutland <mark.rutland@am.com>,
Sami Tolvanen <samitolvanen@google.com>,
kernel-team@android.com, Ard Biesheuvel <ardb@kernel.org>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 4/6] scs: Move scs_overflow_check() out of architecture code
Date: Mon, 18 May 2020 17:44:00 +0100 [thread overview]
Message-ID: <20200518164359.GQ32394@willie-the-truck> (raw)
In-Reply-To: <202005180823.A9C8925ED@keescook>
On Mon, May 18, 2020 at 08:31:49AM -0700, Kees Cook wrote:
> On Mon, May 18, 2020 at 02:32:31PM +0100, Mark Rutland wrote:
> > On Mon, May 18, 2020 at 02:23:47PM +0100, Will Deacon wrote:
> > > This is something I would like to revisit, but we need more
> > > information from Sami about why Android rejected the larger allocation
> > > size, since I don't think there's an awful lot of point merging this
> > > series if Android doesn't pick it up.
> >
> > Indeed. I'd certainly prefer the robustness of a VMAP'd SCS if we can do
> > that.
>
> For smaller devices, the memory overhead was too high. (i.e. 4x more
> memory allocated to kernel stacks -- 4k vs 1k per thread.)
I just don't see an extra 3k per thread as being a real issue (the main
stack is 16k already). Even just the CPU register state is around 1k.
But I'd be very keen to see numbers/performance data that proves me wrong.
Will
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next prev parent reply other threads:[~2020-05-18 16:44 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-15 17:27 [PATCH 0/6] Clean up Shadow Call Stack patches for 5.8 Will Deacon
2020-05-15 17:27 ` [PATCH 1/6] arm64: scs: Store absolute SCS stack pointer value in thread_info Will Deacon
2020-05-18 11:37 ` Mark Rutland
2020-05-18 13:37 ` Will Deacon
2020-05-15 17:27 ` [PATCH 2/6] scs: Move accounting into alloc/free functions Will Deacon
2020-05-18 11:38 ` Mark Rutland
2020-05-18 13:39 ` Will Deacon
2020-05-15 17:27 ` [PATCH 3/6] arm64: scs: Use 'scs_sp' register alias for x18 Will Deacon
2020-05-18 11:55 ` Mark Rutland
2020-05-18 13:03 ` Will Deacon
2020-05-18 13:13 ` Mark Rutland
2020-05-15 17:27 ` [PATCH 4/6] scs: Move scs_overflow_check() out of architecture code Will Deacon
2020-05-18 12:12 ` Mark Rutland
2020-05-18 13:23 ` Will Deacon
2020-05-18 13:32 ` Mark Rutland
2020-05-18 15:31 ` Kees Cook
2020-05-18 16:44 ` Will Deacon [this message]
2020-05-15 17:27 ` [PATCH 5/6] scs: Remove references to asm/scs.h from core code Will Deacon
2020-05-18 12:15 ` Mark Rutland
2020-05-15 17:27 ` [PATCH 6/6] scs: Move DEFINE_SCS macro into " Will Deacon
2020-05-18 12:14 ` Mark Rutland
2020-05-18 13:26 ` Will Deacon
2020-05-18 13:37 ` Mark Rutland
2020-05-15 20:42 ` [PATCH 0/6] Clean up Shadow Call Stack patches for 5.8 Sami Tolvanen
2020-05-18 13:52 ` Will Deacon
2020-05-18 15:43 ` Sami Tolvanen
2020-05-18 16:49 ` Will Deacon
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