From: Will Deacon <will@kernel.org>
Date: Wed, 15 Jan 2020 14:06:37 +0000 (+0000)
Subject: arm64: Use register field helper in kaslr_requires_kpti()
X-Git-Tag: v5.6-rc1~208^2~4^4~1
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=a569f5f37203451d5378cb7de45f643bcb93d5e9;p=thirdparty%2Fkernel%2Flinux.git

arm64: Use register field helper in kaslr_requires_kpti()

Rather than open-code the extraction of the E0PD field from the MMFR2
register, we can use the cpuid_feature_extract_unsigned_field() helper
instead.

Acked-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
---

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index d5242b44dc5a2..1ebeb5bc17d22 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -980,7 +980,6 @@ has_useable_cnp(const struct arm64_cpu_capabilities *entry, int scope)
  */
 bool kaslr_requires_kpti(void)
 {
-	u64 ftr;
 	if (!IS_ENABLED(CONFIG_RANDOMIZE_BASE))
 		return false;
 
@@ -989,8 +988,9 @@ bool kaslr_requires_kpti(void)
 	 * where available.
 	 */
 	if (IS_ENABLED(CONFIG_ARM64_E0PD)) {
-		ftr = read_sysreg_s(SYS_ID_AA64MMFR2_EL1);
-		if ((ftr >> ID_AA64MMFR2_E0PD_SHIFT) & 0xf)
+		u64 mmfr2 = read_sysreg_s(SYS_ID_AA64MMFR2_EL1);
+		if (cpuid_feature_extract_unsigned_field(mmfr2,
+						ID_AA64MMFR2_E0PD_SHIFT))
 			return false;
 	}