From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vladimir Murzin Subject: Re: [PATCH 06/14] ARM: spectre-v2: harden branch predictor on context switches Date: Wed, 16 May 2018 12:33:54 +0100 Message-ID: <0ddd02c0-0af6-e89a-e6ea-b2bd1290dfaf@arm.com> References: <20180516105949.GJ16141@n2100.armlinux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Language: en-GB 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: Russell King , linux-arm-kernel@lists.infradead.org Cc: Marc Zyngier , Florian Fainelli , kvmarm@lists.cs.columbia.edu, Christoffer Dall List-Id: kvmarm@lists.cs.columbia.edu On 16/05/18 12:01, Russell King wrote: > __v7_cr7mp_proc_info: > .long 0x410fc170 > .long 0xff0ffff0 > - __v7_proc __v7_cr7mp_proc_info, __v7_cr7mp_setup > + __v7_proc __v7_cr7mp_proc_info, __v7_cr7mp_setup, proc_fns = HARDENED_BPIALL_PROCESSOR_FUNCTIONS > .size __v7_cr7mp_proc_info, . - __v7_cr7mp_proc_info > > /* > @@ -649,7 +700,7 @@ ENDPROC(__v7_setup) > __v7_cr8mp_proc_info: > .long 0x410fc180 > .long 0xff0ffff0 > - __v7_proc __v7_cr8mp_proc_info, __v7_cr8mp_setup > + __v7_proc __v7_cr8mp_proc_info, __v7_cr8mp_setup, proc_fns = HARDENED_BPIALL_PROCESSOR_FUNCTIONS > .size __v7_cr8mp_proc_info, . - __v7_cr8mp_proc_info For R-class cores, the mitigation doesn't make much sense since we do not enforce user/kernel isolation anyway. I believe the same also applies to A-class cores built with !MMU, so you might want to guard CPU_SPECTRE with MMU in PATCH 05/14. Cheers Vladimir From mboxrd@z Thu Jan 1 00:00:00 1970 From: vladimir.murzin@arm.com (Vladimir Murzin) Date: Wed, 16 May 2018 12:33:54 +0100 Subject: [PATCH 06/14] ARM: spectre-v2: harden branch predictor on context switches In-Reply-To: References: <20180516105949.GJ16141@n2100.armlinux.org.uk> Message-ID: <0ddd02c0-0af6-e89a-e6ea-b2bd1290dfaf@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 16/05/18 12:01, Russell King wrote: > __v7_cr7mp_proc_info: > .long 0x410fc170 > .long 0xff0ffff0 > - __v7_proc __v7_cr7mp_proc_info, __v7_cr7mp_setup > + __v7_proc __v7_cr7mp_proc_info, __v7_cr7mp_setup, proc_fns = HARDENED_BPIALL_PROCESSOR_FUNCTIONS > .size __v7_cr7mp_proc_info, . - __v7_cr7mp_proc_info > > /* > @@ -649,7 +700,7 @@ ENDPROC(__v7_setup) > __v7_cr8mp_proc_info: > .long 0x410fc180 > .long 0xff0ffff0 > - __v7_proc __v7_cr8mp_proc_info, __v7_cr8mp_setup > + __v7_proc __v7_cr8mp_proc_info, __v7_cr8mp_setup, proc_fns = HARDENED_BPIALL_PROCESSOR_FUNCTIONS > .size __v7_cr8mp_proc_info, . - __v7_cr8mp_proc_info For R-class cores, the mitigation doesn't make much sense since we do not enforce user/kernel isolation anyway. I believe the same also applies to A-class cores built with !MMU, so you might want to guard CPU_SPECTRE with MMU in PATCH 05/14. Cheers Vladimir