50a9ff6df4
The kernel is moved ahead to version 3.10.0-693.21.1.el7 To summarize: CVE-2017-5753 [bounds check bypass] aka 'Spectre Variant 1' This is fixed by load fences and is "baked in" and cannot be turned off. CVE-2017-5715 [branch target injection] aka 'Spectre Variant 2' This is fixed by a combination of retpolines and IBPB, or IBRS+IBPB if on skylake. This requires a microcode change in the processors. This feature, if on, has a significant performance impact. It is assumed on unless turned off via the "nospectre_v2" bootarg. CVE-2017-5754 [rogue data cache load] aka 'Meltdown' aka 'Variant 3' This is fixed by page table isolation using the Kaiser patches. This feature is assumed on unless turned off via the "nopti" bootarg. As of the commit date, we have changed the installer kickstarts to issue both "nopti nospectre_v2" bootargs to minimize realtime impacts by default. The customer will be able to optionally sacrifice performance for extra security at datafill time. Change-Id: Id7c99923f2ee2ee91f77c7bd9940e684eff8b476 Signed-off-by: Jim Somerville <Jim.Somerville@windriver.com>
48 lines
1.9 KiB
Diff
48 lines
1.9 KiB
Diff
From 011cad0bf33dc86ce40fe18557b19a42fbc4e657 Mon Sep 17 00:00:00 2001
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Message-Id: <011cad0bf33dc86ce40fe18557b19a42fbc4e657.1522097754.git.Jim.Somerville@windriver.com>
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In-Reply-To: <f4706beaf86081b0890ea616082913f8f51823ff.1522097754.git.Jim.Somerville@windriver.com>
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References: <f4706beaf86081b0890ea616082913f8f51823ff.1522097754.git.Jim.Somerville@windriver.com>
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From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
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Date: Thu, 15 Dec 2016 15:37:47 -0800
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Subject: [PATCH 16/27] rcu: Don't wake rcuc/X kthreads on NOCB CPUs
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[ upstream 630c7ed9ca0608912fa7c8591d05dfc8742dc9e6 in tip repo ]
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Chris Friesen notice that rcuc/X kthreads were consuming CPU even on
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NOCB CPUs. This makes no sense because the only purpose or these
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kthreads is to invoke normal (non-offloaded) callbacks, of which there
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will never be any on NOCB CPUs. This problem was due to a bug in
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cpu_has_callbacks_ready_to_invoke(), which should have been checking
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->nxttail[RCU_NEXT_TAIL] for NULL, but which was instead (incorrectly)
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checking ->nxttail[RCU_DONE_TAIL]. Because ->nxttail[RCU_DONE_TAIL] is
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never NULL, the only effect is to cause the rcuc/X kthread to execute
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when it should not do so.
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This commit therefore checks ->nxttail[RCU_NEXT_TAIL], which is NULL
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for NOCB CPUs.
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Reported-by: Chris Friesen <chris.friesen@windriver.com>
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Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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Signed-off-by: Jim Somerville <Jim.Somerville@windriver.com>
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---
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kernel/rcutree.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/kernel/rcutree.c b/kernel/rcutree.c
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index f46e3e4..ac3dfb7 100644
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--- a/kernel/rcutree.c
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+++ b/kernel/rcutree.c
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@@ -300,7 +300,7 @@ static int
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cpu_has_callbacks_ready_to_invoke(struct rcu_data *rdp)
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{
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return &rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL] &&
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- rdp->nxttail[RCU_DONE_TAIL] != NULL;
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+ rdp->nxttail[RCU_NEXT_TAIL] != NULL;
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}
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/*
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--
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1.8.3.1
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