rebase patches on top of Ubuntu-4.15.0-35.38
(generated with debian/scripts/import-upstream-tag) Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
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@ -54,7 +54,7 @@ Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
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2 files changed, 110 insertions(+)
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2 files changed, 110 insertions(+)
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diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
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diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
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index e1c10a202abe..e40248310433 100644
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index 51210d10d905..ceb1b471d249 100644
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--- a/Documentation/admin-guide/kernel-parameters.txt
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--- a/Documentation/admin-guide/kernel-parameters.txt
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+++ b/Documentation/admin-guide/kernel-parameters.txt
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+++ b/Documentation/admin-guide/kernel-parameters.txt
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@@ -3049,6 +3049,15 @@
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@@ -3049,6 +3049,15 @@
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@ -1,95 +0,0 @@
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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Jiri Kosina <jkosina@suse.cz>
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Date: Wed, 29 Aug 2018 19:17:40 +0000
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Subject: [PATCH] x86/speculation: Protect against userspace-userspace
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spectreRSB
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The article "Spectre Returns! Speculation Attacks using the Return Stack
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Buffer" [1] describes two new (sub-)variants of spectrev2-like attacks,
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making use solely of the RSB contents even on CPUs that don't fallback to
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BTB on RSB underflow (Skylake+).
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Mitigate userspace-userspace attacks by always unconditionally filling RSB on
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context switch when the generic spectrev2 mitigation has been enabled.
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[1] https://arxiv.org/pdf/1807.07940.pdf
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Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
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Acked-by: Tim Chen <tim.c.chen@linux.intel.com>
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Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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Cc: Borislav Petkov <bp@suse.de>
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Cc: David Woodhouse <dwmw@amazon.co.uk>
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Cc: Peter Zijlstra <peterz@infradead.org>
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Cc: Linus Torvalds <torvalds@linux-foundation.org>
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Cc: stable@vger.kernel.org
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Link: https://lkml.kernel.org/r/nycvar.YFH.7.76.1807261308190.997@cbobk.fhfr.pm
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CVE-2017-5715 (SpectreRSB sub-variant)
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(cherry picked from commit fdf82a7856b32d905c39afc85e34364491e46346)
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Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
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Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
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---
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arch/x86/kernel/cpu/bugs.c | 38 +++++++-------------------------------
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1 file changed, 7 insertions(+), 31 deletions(-)
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diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
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index 700b4c0a93a2..edfc64a8a154 100644
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--- a/arch/x86/kernel/cpu/bugs.c
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+++ b/arch/x86/kernel/cpu/bugs.c
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@@ -322,23 +322,6 @@ static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void)
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return cmd;
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}
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-/* Check for Skylake-like CPUs (for RSB handling) */
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-static bool __init is_skylake_era(void)
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-{
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- if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
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- boot_cpu_data.x86 == 6) {
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- switch (boot_cpu_data.x86_model) {
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- case INTEL_FAM6_SKYLAKE_MOBILE:
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- case INTEL_FAM6_SKYLAKE_DESKTOP:
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- case INTEL_FAM6_SKYLAKE_X:
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- case INTEL_FAM6_KABYLAKE_MOBILE:
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- case INTEL_FAM6_KABYLAKE_DESKTOP:
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- return true;
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- }
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- }
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- return false;
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-}
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-
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static void __init spectre_v2_select_mitigation(void)
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{
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enum spectre_v2_mitigation_cmd cmd = spectre_v2_parse_cmdline();
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@@ -399,22 +382,15 @@ static void __init spectre_v2_select_mitigation(void)
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pr_info("%s\n", spectre_v2_strings[mode]);
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/*
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- * If neither SMEP nor PTI are available, there is a risk of
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- * hitting userspace addresses in the RSB after a context switch
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- * from a shallow call stack to a deeper one. To prevent this fill
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- * the entire RSB, even when using IBRS.
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+ * If spectre v2 protection has been enabled, unconditionally fill
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+ * RSB during a context switch; this protects against two independent
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+ * issues:
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*
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- * Skylake era CPUs have a separate issue with *underflow* of the
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- * RSB, when they will predict 'ret' targets from the generic BTB.
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- * The proper mitigation for this is IBRS. If IBRS is not supported
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- * or deactivated in favour of retpolines the RSB fill on context
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- * switch is required.
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+ * - RSB underflow (and switch to BTB) on Skylake+
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+ * - SpectreRSB variant of spectre v2 on X86_BUG_SPECTRE_V2 CPUs
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*/
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- if ((!boot_cpu_has(X86_FEATURE_PTI) &&
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- !boot_cpu_has(X86_FEATURE_SMEP)) || is_skylake_era()) {
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- setup_force_cpu_cap(X86_FEATURE_RSB_CTXSW);
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- pr_info("Spectre v2 mitigation: Filling RSB on context switch\n");
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- }
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+ setup_force_cpu_cap(X86_FEATURE_RSB_CTXSW);
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+ pr_info("Spectre v2 / SpectreRSB mitigation: Filling RSB on context switch\n");
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/* Initialize Indirect Branch Prediction Barrier if supported */
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if (boot_cpu_has(X86_FEATURE_IBPB)) {
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