From: Will Deacon <will.deacon@arm.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: ard.biesheuvel@linaro.org, kernel-hardening@lists.openwall.com,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, akashi.takahiro@linaro.org,
catalin.marinas@arm.com, dave.martin@arm.com,
james.morse@arm.com, labbott@fedoraproject.org,
keescook@chromium.org
Subject: Re: [RFC PATCH 1/6] arm64: use tpidr_el1 for current, free sp_el0
Date: Fri, 14 Jul 2017 02:30:54 +0100 [thread overview]
Message-ID: <20170714013054.GE22336@arm.com> (raw)
In-Reply-To: <1499898783-25732-2-git-send-email-mark.rutland@arm.com>
On Wed, Jul 12, 2017 at 11:32:58PM +0100, Mark Rutland wrote:
> Today we use TPIDR_EL1 for our percpu offset, and SP_EL0 for current
> (and current::thread_info, which is at offset 0).
>
> Using SP_EL0 in this way prevents us from using EL1 thread mode, where
> SP_EL0 is not addressable (since it's used as the active SP). It also
> means we can't use SP_EL0 for other purposes (e.g. as a
> scratch-register).
>
> This patch frees up SP_EL0 for such usage, by storing the percpu offset
> in current::thread_info, and using TPIDR_EL1 to store current. As we no
> longer need to update SP_EL0 at EL0 exception boundaries, this allows us
> to delete some code.
Does this mean we can just use asm-generic/percpu.h?
Will
next prev parent reply other threads:[~2017-07-14 1:30 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-12 22:32 [RFC PATCH 0/6] arm64: alternative VMAP_STACK implementation Mark Rutland
2017-07-12 22:32 ` [RFC PATCH 1/6] arm64: use tpidr_el1 for current, free sp_el0 Mark Rutland
2017-07-14 1:30 ` Will Deacon [this message]
2017-07-12 22:32 ` [RFC PATCH 2/6] arm64: avoid open-coding THREAD_SIZE{,_ORDER} Mark Rutland
2017-07-13 10:18 ` James Morse
2017-07-13 11:26 ` Mark Rutland
2017-07-12 22:33 ` [RFC PATCH 3/6] arm64: pad stacks to PAGE_SIZE for VMAP_STACK Mark Rutland
2017-07-12 22:33 ` [RFC PATCH 4/6] arm64: pass stack base to secondary_start_kernel Mark Rutland
2017-07-12 22:33 ` [RFC PATCH 5/6] arm64: keep track of current stack Mark Rutland
2017-07-12 22:33 ` [RFC PATCH 6/6] arm64: add VMAP_STACK and detect out-of-bounds SP Mark Rutland
2017-07-13 6:58 ` Ard Biesheuvel
2017-07-13 10:49 ` Mark Rutland
2017-07-13 11:49 ` Ard Biesheuvel
2017-07-13 16:10 ` Mark Rutland
2017-07-13 17:55 ` [kernel-hardening] " Mark Rutland
2017-07-13 18:28 ` Ard Biesheuvel
2017-07-14 10:32 ` Mark Rutland
2017-07-14 10:48 ` Ard Biesheuvel
2017-07-14 12:27 ` Ard Biesheuvel
2017-07-14 14:06 ` Mark Rutland
2017-07-14 14:14 ` Ard Biesheuvel
2017-07-14 14:39 ` Robin Murphy
2017-07-14 15:03 ` Robin Murphy
2017-07-14 15:15 ` Ard Biesheuvel
2017-07-14 15:25 ` Mark Rutland
2017-07-14 21:27 ` Mark Rutland
2017-07-16 0:03 ` Ard Biesheuvel
2017-07-18 21:53 ` Laura Abbott
2017-07-19 8:08 ` Ard Biesheuvel
2017-07-19 23:32 ` Laura Abbott
2017-07-20 5:35 ` Ard Biesheuvel
2017-07-20 8:36 ` James Morse
2017-07-20 8:56 ` Ard Biesheuvel
2017-07-20 17:30 ` Ard Biesheuvel
2017-07-20 19:10 ` Laura Abbott
2017-07-14 12:52 ` Mark Rutland
2017-07-14 12:55 ` Ard Biesheuvel
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