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Subject[PATCH] arm64: cpufeature: make sure cpu_mitigations_off then kpti off
Date
From: Liu Song <liusong@linux.alibaba.com>

If kaslr is enabled, kpti cannot be turned off even if "mitigations=off",
adjust the code order to ensure that kpti is off when "mitigations=off".

Signed-off-by: Liu Song <liusong@linux.alibaba.com>
---
arch/arm64/kernel/cpufeature.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 42ea2bd..27d4850 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1616,6 +1616,11 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
__kpti_forced = -1;
}

+ if (cpu_mitigations_off() && !__kpti_forced) {
+ str = "mitigations=off";
+ __kpti_forced = -1;
+ }
+
/* Useful for KASLR robustness */
if (kaslr_requires_kpti()) {
if (!__kpti_forced) {
@@ -1624,11 +1629,6 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
}
}

- if (cpu_mitigations_off() && !__kpti_forced) {
- str = "mitigations=off";
- __kpti_forced = -1;
- }
-
if (!IS_ENABLED(CONFIG_UNMAP_KERNEL_AT_EL0)) {
pr_info_once("kernel page table isolation disabled by kernel configuration\n");
return false;
--
1.8.3.1
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