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SubjectRe: [PATCH v2 00/17] arm64 SSBD (aka Spectre-v4) mitigation
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Hi Catalin,

On 31/05/18 17:41, Catalin Marinas wrote:
> On Tue, May 29, 2018 at 01:11:04PM +0100, Marc Zyngier wrote:
>> Marc Zyngier (17):
>> arm/arm64: smccc: Add SMCCC-specific return codes
>> arm64: Call ARCH_WORKAROUND_2 on transitions between EL0 and EL1
>> arm64: Add per-cpu infrastructure to call ARCH_WORKAROUND_2
>> arm64: Add ARCH_WORKAROUND_2 probing
>> arm64: Add 'ssbd' command-line option
>> arm64: ssbd: Add global mitigation state accessor
>> arm64: ssbd: Skip apply_ssbd if not using dynamic mitigation
>> arm64: ssbd: Restore mitigation status on CPU resume
>> arm64: ssbd: Introduce thread flag to control userspace mitigation
>> arm64: ssbd: Add prctl interface for per-thread mitigation
>> arm64: KVM: Add HYP per-cpu accessors
>> arm64: KVM: Add ARCH_WORKAROUND_2 support for guests
>> arm64: KVM: Handle guest's ARCH_WORKAROUND_2 requests
>> arm64: KVM: Add ARCH_WORKAROUND_2 discovery through
>> ARCH_FEATURES_FUNC_ID
>
> I queued the 14 patches above for 4.18.

I just realized that your for-next/core branch is based on
4.17-rc4, which means arch/arm64/kernel/ssbd.c won't compile
(it relies on some of the symbols introduced with the x86
stuff in 4.17-rc7.

You can work around it by adding the following hack:

From 8a0dbe9fb468c03b3913d17af9dce7358f899ee3 Mon Sep 17 00:00:00 2001
From: Marc Zyngier <marc.zyngier@arm.com>
Date: Thu, 31 May 2018 17:54:11 +0100
Subject: [PATCH] fixup! arm64: ssbd: Add prctl interface for per-thread
mitigation

---
arch/arm64/kernel/ssbd.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/arch/arm64/kernel/ssbd.c b/arch/arm64/kernel/ssbd.c
index 07b12c034ec2..3432e5ef9f41 100644
--- a/arch/arm64/kernel/ssbd.c
+++ b/arch/arm64/kernel/ssbd.c
@@ -11,7 +11,9 @@

/*
* prctl interface for SSBD
+ * FIXME: Drop the below ifdefery once merged in 4.18.
*/
+#ifdef PR_SPEC_STORE_BYPASS
static int ssbd_prctl_set(struct task_struct *task, unsigned long ctrl)
{
int state = arm64_get_ssbd_state();
@@ -105,3 +107,4 @@ int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which)
return -ENODEV;
}
}
+#endif /* PR_SPEC_STORE_BYPASS */
--
2.17.1

Thanks,

M.
--
Jazz is not dead. It just smells funny...

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