From mboxrd@z Thu Jan 1 00:00:00 1970 From: Krzysztof Kozlowski Subject: Re: [PATCH 5/5] ARM: spectre-v2: per-CPU vtables to work around big.Little systems Date: Fri, 5 Oct 2018 11:35:52 +0200 Message-ID: References: <20180919094802.GH30658@n2100.armlinux.org.uk> <20181005090941eucas1p14031cd38d78e9d561975925bf977727d~aq0-OFZeE1866318663eucas1p1b@eucas1p1.samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20181005090941eucas1p14031cd38d78e9d561975925bf977727d~aq0-OFZeE1866318663eucas1p1b@eucas1p1.samsung.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Marek Szyprowski Cc: mark.rutland@arm.com, "linux-samsung-soc@vger.kernel.org" , julien.thierry@arm.com, marc.zyngier@arm.com, will.deacon@arm.com, dietmar.eggemann@arm.com, rmk+kernel@armlinux.org.uk, Morten.Rasmussen@arm.com, linux-arm-kernel@lists.infradead.org, Qais.Yousef@arm.com List-Id: linux-samsung-soc@vger.kernel.org On Fri, 5 Oct 2018 at 11:09, Marek Szyprowski wrote: > > Hi All, > > On 2018-09-19 11:49, Russell King wrote: > > In big.Little systems, some CPUs require the Spectre workarounds in > > paths such as the context switch, but other CPUs do not. In order > > to handle these differences, we need per-CPU vtables. > > > > We are unable to use the kernel's per-CPU variables to support this > > as per-CPU is not initialised at times when we need access to the > > vtables, so we have to use an array indexed by logical CPU number. > > > > Signed-off-by: Russell King > > This patch causes lots of kernel 'BUG' messages on all Samsung Exynos > boards. It started to appear since it has been merged to linux-next > on 20181002. I wonder if this issue is Exynos specific or there are > some patches missing in linux-next, which should fix those 'BUGS'. > If this is Exynos specific, please let us know what should be changed > in Exynos platform code to avoid this issue. Thanks Marek for narrowing this down. I confirm. All my Exynos boards experience this. Full logs: https://krzk.eu/#/builders/1/builds/2811/steps/12/logs/serial0 Best regards, Krzysztof From mboxrd@z Thu Jan 1 00:00:00 1970 From: krzk@kernel.org (Krzysztof Kozlowski) Date: Fri, 5 Oct 2018 11:35:52 +0200 Subject: [PATCH 5/5] ARM: spectre-v2: per-CPU vtables to work around big.Little systems In-Reply-To: <20181005090941eucas1p14031cd38d78e9d561975925bf977727d~aq0-OFZeE1866318663eucas1p1b@eucas1p1.samsung.com> References: <20180919094802.GH30658@n2100.armlinux.org.uk> <20181005090941eucas1p14031cd38d78e9d561975925bf977727d~aq0-OFZeE1866318663eucas1p1b@eucas1p1.samsung.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, 5 Oct 2018 at 11:09, Marek Szyprowski wrote: > > Hi All, > > On 2018-09-19 11:49, Russell King wrote: > > In big.Little systems, some CPUs require the Spectre workarounds in > > paths such as the context switch, but other CPUs do not. In order > > to handle these differences, we need per-CPU vtables. > > > > We are unable to use the kernel's per-CPU variables to support this > > as per-CPU is not initialised at times when we need access to the > > vtables, so we have to use an array indexed by logical CPU number. > > > > Signed-off-by: Russell King > > This patch causes lots of kernel 'BUG' messages on all Samsung Exynos > boards. It started to appear since it has been merged to linux-next > on 20181002. I wonder if this issue is Exynos specific or there are > some patches missing in linux-next, which should fix those 'BUGS'. > If this is Exynos specific, please let us know what should be changed > in Exynos platform code to avoid this issue. Thanks Marek for narrowing this down. I confirm. All my Exynos boards experience this. Full logs: https://krzk.eu/#/builders/1/builds/2811/steps/12/logs/serial0 Best regards, Krzysztof