From: Jeremy Linton jeremy.linton@arm.com
[ Upstream commit e5ce5e7267ddcbe13ab9ead2542524e1b7993e5a ]
There are various reasons, such as benchmarking, to disable spectrev2 mitigation on a machine. Provide a command-line option to do so.
Signed-off-by: Jeremy Linton jeremy.linton@arm.com Reviewed-by: Suzuki K Poulose suzuki.poulose@arm.com Reviewed-by: Andre Przywara andre.przywara@arm.com Reviewed-by: Catalin Marinas catalin.marinas@arm.com Tested-by: Stefan Wahren stefan.wahren@i2se.com Cc: Jonathan Corbet corbet@lwn.net Cc: linux-doc@vger.kernel.org Signed-off-by: Will Deacon will.deacon@arm.com Signed-off-by: Ard Biesheuvel ard.biesheuvel@linaro.org --- 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 e8ddf0ef232e..cc2f5c9a8161 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2866,10 +2866,10 @@ (bounds check bypass). With this option data leaks are possible in the system.
- nospectre_v2 [X86,PPC_FSL_BOOK3E] 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,PPC_FSL_BOOK3E,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 10571a378f4c..2394a105ebf4 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -189,6 +189,14 @@ 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) { @@ -200,6 +208,11 @@ enable_smccc_arch_workaround_1(const struct arm64_cpu_capabilities *entry) 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;