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From: Li Kun <hw.likun@huawei.com>
To: Will Deacon <will.deacon@arm.com>, Yisheng Xie <xieyisheng1@huawei.com>
Cc: <lorenzo.pieralisi@arm.com>, <ard.biesheuvel@linaro.org>,
	<marc.zyngier@arm.com>, <catalin.marinas@arm.com>,
	<linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>, <labbott@redhat.com>,
	<christoffer.dall@linaro.org>
Subject: Re: [PATCH v2 07/11] arm64: Add skeleton to harden the branch predictor against aliasing attacks
Date: Fri, 19 Jan 2018 11:37:24 +0800	[thread overview]
Message-ID: <a8f3579a-9afd-c39a-fad7-826eba8e9ac8@huawei.com> (raw)
In-Reply-To: <20180117100715.GA27892@arm.com>

Hi will,


在 2018/1/17 18:07, Will Deacon 写道:
> On Wed, Jan 17, 2018 at 12:10:33PM +0800, Yisheng Xie wrote:
>> Hi Will,
>>
>> On 2018/1/5 21:12, Will Deacon wrote:
>>> diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c
>>> index 5f7097d0cd12..d99b36555a16 100644
>>> --- a/arch/arm64/mm/context.c
>>> +++ b/arch/arm64/mm/context.c
>>> @@ -246,6 +246,8 @@ asmlinkage void post_ttbr_update_workaround(void)
>>>   			"ic iallu; dsb nsh; isb",
>>>   			ARM64_WORKAROUND_CAVIUM_27456,
>>>   			CONFIG_CAVIUM_ERRATUM_27456));
>>> +
>>> +	arm64_apply_bp_hardening();
>>>   }
>> post_ttbr_update_workaround was used for fix Cavium erratum 2745? so does that
>> means, if we do not have this erratum, we do not need arm64_apply_bp_hardening()?
>> when mm_swtich and kernel_exit?
>>
>>  From the code logical, it seems not only related to erratum 2745 anymore?
>> should it be renamed?
> post_ttbr_update_workaround just runs code after a TTBR update, which
> includes mitigations against variant 2 of "spectre" and also a workaround
> for a Cavium erratum. These are separate issues.
But AFAIU, according to the theory of spectre, we don't need to clear 
the BTB every time we return to user?
If we enable CONFIG_ARM64_SW_TTBR0_PAN, there will be a call to 
arm64_apply_bp_hardening every time kernel exit to el0.
kernel_exit
     post_ttbr_update_workaround
         arm64_apply_bp_hardening
>
> Will
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

-- 
Best Regards
Li Kun

  parent reply	other threads:[~2018-01-19  3:40 UTC|newest]

Thread overview: 68+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-05 13:12 [PATCH v2 00/11] arm64 kpti hardening and variant 2 workarounds Will Deacon
2018-01-05 13:12 ` [PATCH v2 01/11] arm64: use RET instruction for exiting the trampoline Will Deacon
2018-01-06 13:13   ` Ard Biesheuvel
2018-01-08 14:33     ` Will Deacon
2018-01-08 14:38       ` Ard Biesheuvel
2018-01-08 14:45         ` Will Deacon
2018-01-08 14:56           ` Ard Biesheuvel
2018-01-08 15:27         ` David Laight
2018-01-05 13:12 ` [PATCH v2 02/11] arm64: Kconfig: Reword UNMAP_KERNEL_AT_EL0 kconfig entry Will Deacon
2018-01-05 13:12 ` [PATCH v2 03/11] arm64: Take into account ID_AA64PFR0_EL1.CSV3 Will Deacon
2018-01-08  7:24   ` [v2,03/11] " Jayachandran C
2018-01-08  9:20     ` Marc Zyngier
2018-01-08 17:40       ` Jayachandran C
2018-01-08 17:51         ` Will Deacon
2018-01-08 18:22           ` Alan Cox
2018-01-09  4:06           ` Jayachandran C
2018-01-09 10:00             ` Will Deacon
2018-01-19  1:00               ` Jon Masters
2018-01-08 17:52         ` Marc Zyngier
2018-01-08 17:06     ` Will Deacon
2018-01-08 17:50       ` Jayachandran C
2018-01-05 13:12 ` [PATCH v2 04/11] arm64: cpufeature: Pass capability structure to ->enable callback Will Deacon
2018-01-05 13:12 ` [PATCH v2 05/11] drivers/firmware: Expose psci_get_version through psci_ops structure Will Deacon
2018-01-05 13:12 ` [PATCH v2 06/11] arm64: Move post_ttbr_update_workaround to C code Will Deacon
2018-01-05 13:12 ` [PATCH v2 07/11] arm64: Add skeleton to harden the branch predictor against aliasing attacks Will Deacon
2018-01-08  0:15   ` Jon Masters
2018-01-08 12:16   ` James Morse
2018-01-08 14:26     ` Will Deacon
2018-01-17  4:10   ` Yisheng Xie
2018-01-17 10:07     ` Will Deacon
2018-01-18  8:37       ` Yisheng Xie
2018-01-19  3:37       ` Li Kun [this message]
2018-01-19 14:28         ` Will Deacon
2018-01-22  6:52           ` Li Kun
2018-01-05 13:12 ` [PATCH v2 08/11] arm64: KVM: Use per-CPU vector when BP hardening is enabled Will Deacon
2018-01-05 13:12 ` [PATCH v2 09/11] arm64: KVM: Make PSCI_VERSION a fast path Will Deacon
2018-01-05 13:12 ` [PATCH v2 10/11] arm64: cputype: Add missing MIDR values for Cortex-A72 and Cortex-A75 Will Deacon
2018-01-05 13:12 ` [PATCH v2 11/11] arm64: Implement branch predictor hardening for affected Cortex-A CPUs Will Deacon
2018-01-05 14:46   ` James Morse
2018-01-05 14:57     ` Marc Zyngier
2018-01-08  6:31   ` [v2, " Jayachandran C
2018-01-08  6:53     ` [PATCH 1/2] arm64: cputype: Add MIDR values for Cavium ThunderX2 CPUs Jayachandran C
2018-01-08  6:53       ` [PATCH 2/2] arm64: Branch predictor hardening for Cavium ThunderX2 Jayachandran C
2018-01-08 16:46         ` Will Deacon
2018-01-08 17:19           ` Jayachandran C
2018-01-08 17:23             ` Will Deacon
2018-01-09  2:26               ` Jayachandran C
2018-01-09  9:53                 ` Will Deacon
2018-01-09 12:47           ` [PATCH v2] " Jayachandran C
2018-01-16 21:50             ` Jon Masters
2018-01-16 21:52             ` Jon Masters
2018-01-16 23:45               ` Jayachandran C
2018-01-17 18:34                 ` Jon Masters
2018-01-18 13:53                 ` Will Deacon
2018-01-18 17:56                   ` Jayachandran C
2018-01-18 18:27                     ` Jon Masters
2018-01-18 23:28                       ` Jayachandran C
2018-01-19  1:17                         ` Jon Masters
2018-01-19 12:22                   ` [PATCH v3 1/2] " Jayachandran C
2018-01-19 12:22                     ` [PATCH v3 2/2] arm64: Turn on KPTI only on CPUs that need it Jayachandran C
2018-01-22 11:41                       ` Will Deacon
2018-01-22 11:51                         ` Ard Biesheuvel
2018-01-22 11:55                           ` Will Deacon
2018-01-22 18:59                         ` Jon Masters
2018-01-19 19:08                     ` [PATCH v3 1/2] arm64: Branch predictor hardening for Cavium ThunderX2 Jon Masters
2018-01-22 11:33                     ` Will Deacon
2018-01-22 19:00                       ` Jon Masters
2018-01-23  9:51                         ` Will Deacon

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