From: Jeremy Linton <jeremy.linton@xxxxxxx>
euler inclusion
category: feature
bugzilla: 11011
DTS: NA
CVE: NA
Patch will be in mainlien kernel 5.2
--------------------------------------------------
There are various reasons, including bencmarking, to disable spectrev2
mitigation on a machine. Provide a command-line to do so.
Signed-off-by: Jeremy Linton <jeremy.linton@xxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: linux-doc@xxxxxxxxxxxxxxx
[Hanjun: fix conflicts which we don't have PPC PPC_FSL_BOOK3E
arch spectre-v2 mitigation in 4.19 kernel, so remvoe PPC_FSL_BOOK3E]
Conflicts:
Documentation/admin-guide/kernel-parameters.txt
Signed-off-by: Hanjun Guo <guohanjun@xxxxxxxxxx>
---
Documentation/admin-guide/kernel-parameters.txt | 8 ++++----
arch/arm64/kernel/cpu_errata.c | 13 +++++++++++++
2 files changed, 17 insertions(+), 4 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index b43fbaa..bbc34c03 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2828,10 +2828,10 @@
check bypass). With this option data leaks are possible
in the system.
- nospectre_v2 [X86] Disable all mitigations for the Spectre variant 2
- (indirect branch prediction) vulnerability. System may
- allow data leaks with this option, which is equivalent
- to spectre_v2=off.
+ nospectre_v2 [X86,ARM64] Disable all mitigations for
+ the Spectre variant 2 (indirect branch prediction)
+ vulnerability. System may allow data leaks with this
+ option.
nospec_store_bypass_disable
[HW] Disable all mitigations for the Speculative Store Bypass vulnerability
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 74e9e80..7e5682c 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -210,6 +210,14 @@ static void qcom_link_stack_sanitization(void)
: "=&r" (tmp));
}
+static bool __nospectre_v2;
+static int __init parse_nospectre_v2(char *str)
+{
+ __nospectre_v2 = true;
+ return 0;
+}
+early_param("nospectre_v2", parse_nospectre_v2);
+
static void
enable_smccc_arch_workaround_1(const struct arm64_cpu_capabilities *entry)
{
@@ -221,6 +229,11 @@ static void qcom_link_stack_sanitization(void)
if (!entry->matches(entry, SCOPE_LOCAL_CPU))
return;
+ if (__nospectre_v2) {
+ pr_info_once("spectrev2 mitigation disabled by command line option\n");
+ return;
+ }
+
if (psci_ops.smccc_version == SMCCC_VERSION_1_0)
return;
--
1.7.12.4
