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From: Will Deacon <will@kernel.org>
To: broonie@kernel.org
Cc: kernel-team@android.com,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Marc Zyngier <maz@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/2] arm64: Simplify early check for broken TX1 when KASLR is enabled
Date: Wed, 15 Jan 2020 14:28:59 +0000	[thread overview]
Message-ID: <20200115142900.28976-2-will@kernel.org> (raw)
In-Reply-To: <20200115142900.28976-1-will@kernel.org>

Now that the decision to use non-global mappings is stored in a variable,
the check to avoid enabling them for the terminally broken ThunderX1
platform can be simplified so that it is only keyed off the MIDR value.

Signed-off-by: Will Deacon <will@kernel.org>
---
 arch/arm64/kernel/cpufeature.c | 15 ++++-----------
 1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 4a031111ceb5..d5242b44dc5a 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -980,9 +980,7 @@ has_useable_cnp(const struct arm64_cpu_capabilities *entry, int scope)
  */
 bool kaslr_requires_kpti(void)
 {
-	bool tx1_bug;
 	u64 ftr;
-
 	if (!IS_ENABLED(CONFIG_RANDOMIZE_BASE))
 		return false;
 
@@ -1000,18 +998,13 @@ bool kaslr_requires_kpti(void)
 	 * Systems affected by Cavium erratum 24756 are incompatible
 	 * with KPTI.
 	 */
-	if (!IS_ENABLED(CONFIG_CAVIUM_ERRATUM_27456)) {
-		tx1_bug = false;
-	} else if (!static_branch_likely(&arm64_const_caps_ready)) {
+	if (IS_ENABLED(CONFIG_CAVIUM_ERRATUM_27456)) {
 		extern const struct midr_range cavium_erratum_27456_cpus[];
 
-		tx1_bug = is_midr_in_range_list(read_cpuid_id(),
-						cavium_erratum_27456_cpus);
-	} else {
-		tx1_bug = __cpus_have_const_cap(ARM64_WORKAROUND_CAVIUM_27456);
+		if (is_midr_in_range_list(read_cpuid_id(),
+					  cavium_erratum_27456_cpus))
+			return false;
 	}
-	if (tx1_bug)
-		return false;
 
 	return kaslr_offset() > 0;
 }
-- 
2.25.0.rc1.283.g88dfdc4193-goog


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  reply	other threads:[~2020-01-15 14:29 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-15 14:28 [PATCH 0/2] A couple of cleanups on top of for-next/e0pd Will Deacon
2020-01-15 14:28 ` Will Deacon [this message]
2020-01-15 14:29 ` [PATCH 2/2] arm64: Use register field helper in kaslr_requires_kpti() Will Deacon
2020-01-15 17:06   ` Mark Brown
2020-01-15 15:11 ` [PATCH 0/2] A couple of cleanups on top of for-next/e0pd Catalin Marinas
2020-01-15 16:47 ` Suzuki Kuruppassery Poulose

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