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From: Catalin Marinas <catalin.marinas@arm.com>
To: Peter Collingbourne <pcc@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>,
	Kostya Serebryany <kcc@google.com>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	linux-arch@vger.kernel.org,
	Richard Earnshaw <Richard.Earnshaw@arm.com>,
	Szabolcs Nagy <szabolcs.nagy@arm.com>,
	Marc Zyngier <maz@kernel.org>,
	Kevin Brodsky <kevin.brodsky@arm.com>,
	linux-mm@kvack.org, Andrey Konovalov <andreyknvl@google.com>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Will Deacon <will@kernel.org>
Subject: Re: [PATCH] arm64: mte: Clear SCTLR_EL1.TCF0 on exec
Date: Wed, 12 Feb 2020 17:03:50 +0000	[thread overview]
Message-ID: <20200212170350.GB587247@arrakis.emea.arm.com> (raw)
In-Reply-To: <20191220014853.223389-1-pcc@google.com>

On Thu, Dec 19, 2019 at 05:48:53PM -0800, Peter Collingbourne wrote:
> On Thu, Dec 19, 2019 at 12:32 PM Peter Collingbourne <pcc@google.com> wrote:
> > On Wed, Dec 11, 2019 at 10:45 AM Catalin Marinas
> > <catalin.marinas@arm.com> wrote:
> > > +       if (current->thread.sctlr_tcf0 != next->thread.sctlr_tcf0)
> > > +               update_sctlr_el1_tcf0(next->thread.sctlr_tcf0);
> >
> > I don't entirely understand why yet, but I've found that this check is
> > insufficient for ensuring consistency between SCTLR_EL1.TCF0 and
> > sctlr_tcf0. In my Android test environment with some processes having
> > sctlr_tcf0=SCTLR_EL1_TCF0_SYNC and others having sctlr_tcf0=0, I am
> > seeing intermittent tag failures coming from the sctlr_tcf0=0
> > processes. With this patch:
[...]
> > Since sysreg_clear_set only sets the sysreg if it ended up changing, I
> > wouldn't expect this to cause a significant performance hit unless
> > just reading SCTLR_EL1 is expensive. That being said, if the
> > inconsistency is indicative of a deeper problem, we should probably
> > address that.
> 
> I tracked it down to the flush_mte_state() function setting sctlr_tcf0 but
> failing to update SCTLR_EL1.TCF0. With this patch I am not seeing any more
> inconsistencies.

Thanks Peter. I folded in your fix.

-- 
Catalin

  parent reply	other threads:[~2020-02-12 17:03 UTC|newest]

Thread overview: 92+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-11 18:40 [PATCH 00/22] arm64: Memory Tagging Extension user-space support Catalin Marinas
2019-12-11 18:40 ` Catalin Marinas
2019-12-11 18:40 ` [PATCH 01/22] mm: Reserve asm-generic prot flags 0x10 and 0x20 for arch use Catalin Marinas
2019-12-11 18:40   ` Catalin Marinas
2019-12-11 19:26   ` Arnd Bergmann
2019-12-11 19:26     ` Arnd Bergmann
2019-12-11 18:40 ` [PATCH 02/22] kbuild: Add support for 'as-instr' to be used in Kconfig files Catalin Marinas
2019-12-11 18:40   ` Catalin Marinas
2019-12-12  5:03   ` Masahiro Yamada
2019-12-12  5:03     ` Masahiro Yamada
2019-12-11 18:40 ` [PATCH 03/22] arm64: alternative: Allow alternative_insn to always issue the first instruction Catalin Marinas
2019-12-11 18:40   ` Catalin Marinas
2019-12-11 18:40 ` [PATCH 04/22] arm64: Use macros instead of hard-coded constants for MAIR_EL1 Catalin Marinas
2019-12-11 18:40   ` Catalin Marinas
2019-12-11 18:40 ` [PATCH 05/22] arm64: mte: system register definitions Catalin Marinas
2019-12-11 18:40   ` Catalin Marinas
2019-12-11 18:40 ` [PATCH 06/22] arm64: mte: CPU feature detection and initial sysreg configuration Catalin Marinas
2019-12-11 18:40   ` Catalin Marinas
2019-12-11 18:40 ` [PATCH 07/22] arm64: mte: Use Normal Tagged attributes for the linear map Catalin Marinas
2019-12-11 18:40   ` Catalin Marinas
2019-12-11 18:40 ` [PATCH 08/22] arm64: mte: Assembler macros and default architecture for .S files Catalin Marinas
2019-12-11 18:40   ` Catalin Marinas
2019-12-11 18:40 ` [PATCH 09/22] arm64: mte: Tags-aware clear_page() implementation Catalin Marinas
2019-12-11 18:40   ` Catalin Marinas
2019-12-11 18:40 ` [PATCH 10/22] arm64: mte: Tags-aware copy_page() implementation Catalin Marinas
2019-12-11 18:40   ` Catalin Marinas
2019-12-11 18:40 ` [PATCH 11/22] arm64: Tags-aware memcmp_pages() implementation Catalin Marinas
2019-12-11 18:40   ` Catalin Marinas
2019-12-11 18:40 ` [PATCH 12/22] arm64: mte: Add specific SIGSEGV codes Catalin Marinas
2019-12-11 18:40   ` Catalin Marinas
2019-12-11 19:31   ` Arnd Bergmann
2019-12-11 19:31     ` Arnd Bergmann
2019-12-12  9:34     ` Catalin Marinas
2019-12-12  9:34       ` Catalin Marinas
2019-12-12 18:26     ` Eric W. Biederman
2019-12-12 18:26       ` Eric W. Biederman
2019-12-17 17:48       ` Catalin Marinas
2019-12-17 17:48         ` Catalin Marinas
2019-12-17 20:06         ` Eric W. Biederman
2019-12-17 20:06           ` Eric W. Biederman
2019-12-11 18:40 ` [PATCH 13/22] arm64: mte: Handle synchronous and asynchronous tag check faults Catalin Marinas
2019-12-11 18:40   ` Catalin Marinas
2019-12-14  1:43   ` Peter Collingbourne
2019-12-14  1:43     ` Peter Collingbourne
2019-12-17 18:01     ` Catalin Marinas
2019-12-17 18:01       ` Catalin Marinas
2019-12-20  1:36       ` [PATCH] arm64: mte: Do not service syscalls after async tag fault Peter Collingbourne
2019-12-20  1:36         ` Peter Collingbourne
2020-02-12 11:09         ` Catalin Marinas
2020-02-18 21:59           ` Peter Collingbourne
2020-02-19 16:16             ` Catalin Marinas
2019-12-11 18:40 ` [PATCH 14/22] mm: Introduce arch_calc_vm_flag_bits() Catalin Marinas
2019-12-11 18:40   ` Catalin Marinas
2019-12-11 18:40 ` [PATCH 15/22] arm64: mte: Add PROT_MTE support to mmap() and mprotect() Catalin Marinas
2019-12-11 18:40   ` Catalin Marinas
2020-01-21 22:06   ` Peter Collingbourne
2019-12-11 18:40 ` [PATCH 16/22] mm: Introduce arch_validate_flags() Catalin Marinas
2019-12-11 18:40   ` Catalin Marinas
2019-12-11 18:40 ` [PATCH 17/22] arm64: mte: Validate the PROT_MTE request via arch_validate_flags() Catalin Marinas
2019-12-11 18:40   ` Catalin Marinas
2019-12-11 18:40 ` [PATCH 18/22] mm: Allow arm64 mmap(PROT_MTE) on RAM-based files Catalin Marinas
2019-12-11 18:40   ` Catalin Marinas
2019-12-11 18:40 ` [PATCH 19/22] arm64: mte: Allow user control of the tag check mode via prctl() Catalin Marinas
2019-12-11 18:40   ` Catalin Marinas
2019-12-19 20:32   ` Peter Collingbourne
2019-12-19 20:32     ` Peter Collingbourne
2019-12-20  1:48     ` [PATCH] arm64: mte: Clear SCTLR_EL1.TCF0 on exec Peter Collingbourne
2019-12-20  1:48       ` Peter Collingbourne
2020-02-12 17:03       ` Catalin Marinas [this message]
2019-12-27 14:34   ` [PATCH 19/22] arm64: mte: Allow user control of the tag check mode via prctl() Kevin Brodsky
2019-12-27 14:34     ` Kevin Brodsky
2020-02-12 11:45     ` Catalin Marinas
2019-12-11 18:40 ` [PATCH 20/22] arm64: mte: Allow user control of the excluded tags " Catalin Marinas
2019-12-11 18:40   ` Catalin Marinas
2019-12-16 14:20   ` Kevin Brodsky
2019-12-16 14:20     ` Kevin Brodsky
2019-12-16 17:30     ` Peter Collingbourne
2019-12-16 17:30       ` Peter Collingbourne
2019-12-17 17:56       ` Catalin Marinas
2019-12-17 17:56         ` Catalin Marinas
2020-06-22 17:17       ` Catalin Marinas
2020-06-22 19:00         ` Peter Collingbourne
2020-06-23 16:42           ` Catalin Marinas
2019-12-11 18:40 ` [PATCH 21/22] arm64: mte: Kconfig entry Catalin Marinas
2019-12-11 18:40   ` Catalin Marinas
2019-12-11 18:40 ` [PATCH 22/22] arm64: mte: Add Memory Tagging Extension documentation Catalin Marinas
2019-12-11 18:40   ` Catalin Marinas
2019-12-24 15:03   ` Kevin Brodsky
2019-12-24 15:03     ` Kevin Brodsky
2019-12-13 18:05 ` [PATCH 00/22] arm64: Memory Tagging Extension user-space support Peter Collingbourne
2019-12-13 18:05   ` Peter Collingbourne
2020-02-13 11:23   ` Catalin Marinas

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