From: Vincenzo Frascino <vincenzo.frascino@arm.com> To: Marc Zyngier <maz@kernel.org> Cc: linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, catalin.marinas@arm.com, will.deacon@arm.com, linux@armlinux.org.uk, luto@kernel.org, tglx@linutronix.de, m.szyprowski@samsung.com, mark.rutland@arm.com Subject: Re: [PATCH] clocksource: Fix arm_arch_timer clockmode when vDSO disabled Date: Fri, 21 Feb 2020 14:48:29 +0000 [thread overview] Message-ID: <c438aa7e-2c96-8c11-bb87-204929a01a20@arm.com> (raw) In-Reply-To: <a81251e813d54caddd56b9aac4b55e85@kernel.org> [-- Attachment #1: Type: text/plain, Size: 1654 bytes --] Hi Marc, On 21/02/2020 13:34, Marc Zyngier wrote: > Vincenzo, > > Please include Mark and myself for anything that touches the arch timers > (get_maintainer.pl will tell you who you need to cc). > Sorry about that, I posted it too quickly without the proper Cc on the patch. > On 2020-02-21 13:03, Vincenzo Frascino wrote: [...] > > This feels pretty clunky. > > I'd extect VDSO_ARCH_CLOCKMODES (or some similar architecture-specific > symbol) to be used for vdso_default, and that symbol to be defined as > VDSO_CLOCKMODE_NONE when CONFIG_GENERIC_GETTIMEOFDAY isn't selected. > My understanding is that currently VDSO_ARCH_CLOCKMODES depending on the architecture can identify one or more clocks. In the case of arm and the arm_arch_timer the arch specific symbol is VDSO_CLOCKMODE_ARCHTIMER (used for vdso_default), which as you are correctly stating has to be defined as VDSO_CLOCKMODE_NONE when CONFIG_GENERIC_GETTIMEOFDAY isn't selected. > Otherwise, you'll end-up replicating the same pattern in every > clock-source that gets used by the VDSO. Based on my investigation this fix should be replicated for all the clocksources used by architectures supported by Unified VDSO and of which VDSOs can be disabled (otherwise the current solution works). After a quick grep on the kernel tree: $ grep -nr "config VDSO" * arch/arm/mm/Kconfig:895:config VDSO Since the only clocksource that falls into these conditions seems to be arm_arch_timer I modified its driver. Please feel free to correct me if I missed or misunderstood something. > > M. -- Regards, Vincenzo [-- Attachment #2: pEpkey.asc --] [-- Type: application/pgp-keys, Size: 14291 bytes --]
WARNING: multiple messages have this Message-ID (diff)
From: Vincenzo Frascino <vincenzo.frascino@arm.com> To: Marc Zyngier <maz@kernel.org> Cc: linux-arch@vger.kernel.org, mark.rutland@arm.com, catalin.marinas@arm.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, linux@armlinux.org.uk, luto@kernel.org, tglx@linutronix.de, linux-arm-kernel@lists.infradead.org, m.szyprowski@samsung.com Subject: Re: [PATCH] clocksource: Fix arm_arch_timer clockmode when vDSO disabled Date: Fri, 21 Feb 2020 14:48:29 +0000 [thread overview] Message-ID: <c438aa7e-2c96-8c11-bb87-204929a01a20@arm.com> (raw) In-Reply-To: <a81251e813d54caddd56b9aac4b55e85@kernel.org> [-- Attachment #1: Type: text/plain, Size: 1654 bytes --] Hi Marc, On 21/02/2020 13:34, Marc Zyngier wrote: > Vincenzo, > > Please include Mark and myself for anything that touches the arch timers > (get_maintainer.pl will tell you who you need to cc). > Sorry about that, I posted it too quickly without the proper Cc on the patch. > On 2020-02-21 13:03, Vincenzo Frascino wrote: [...] > > This feels pretty clunky. > > I'd extect VDSO_ARCH_CLOCKMODES (or some similar architecture-specific > symbol) to be used for vdso_default, and that symbol to be defined as > VDSO_CLOCKMODE_NONE when CONFIG_GENERIC_GETTIMEOFDAY isn't selected. > My understanding is that currently VDSO_ARCH_CLOCKMODES depending on the architecture can identify one or more clocks. In the case of arm and the arm_arch_timer the arch specific symbol is VDSO_CLOCKMODE_ARCHTIMER (used for vdso_default), which as you are correctly stating has to be defined as VDSO_CLOCKMODE_NONE when CONFIG_GENERIC_GETTIMEOFDAY isn't selected. > Otherwise, you'll end-up replicating the same pattern in every > clock-source that gets used by the VDSO. Based on my investigation this fix should be replicated for all the clocksources used by architectures supported by Unified VDSO and of which VDSOs can be disabled (otherwise the current solution works). After a quick grep on the kernel tree: $ grep -nr "config VDSO" * arch/arm/mm/Kconfig:895:config VDSO Since the only clocksource that falls into these conditions seems to be arm_arch_timer I modified its driver. Please feel free to correct me if I missed or misunderstood something. > > M. -- Regards, Vincenzo [-- Attachment #2: pEpkey.asc --] [-- Type: application/pgp-keys, Size: 14291 bytes --] [-- Attachment #3: Type: text/plain, Size: 176 bytes --] _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-02-21 14:48 UTC|newest] Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <CGME20200221130455eucas1p2aa4312aad606b53add889811d8e9fbc7@eucas1p2.samsung.com> 2020-02-21 13:03 ` [PATCH] clocksource: Fix arm_arch_timer clockmode when vDSO disabled Vincenzo Frascino 2020-02-21 13:03 ` Vincenzo Frascino 2020-02-21 13:15 ` Marek Szyprowski 2020-02-21 13:15 ` Marek Szyprowski 2020-02-21 13:34 ` Marc Zyngier 2020-02-21 13:34 ` Marc Zyngier 2020-02-21 14:48 ` Vincenzo Frascino [this message] 2020-02-21 14:48 ` Vincenzo Frascino 2020-02-21 15:28 ` Marc Zyngier 2020-02-21 15:28 ` Marc Zyngier 2020-02-21 15:56 ` Vincenzo Frascino 2020-02-21 15:56 ` Vincenzo Frascino 2020-02-21 16:24 ` Marc Zyngier 2020-02-21 16:24 ` Marc Zyngier 2020-02-21 16:33 ` Vincenzo Frascino 2020-02-21 16:33 ` Vincenzo Frascino
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