[PATCH v6 3/9] arm64: kaslr: drop special case for ThunderX in kaslr_requires_kpti()

[Ard Biesheuvel]

ThunderX is an obsolete platform that shipped without support for the
EFI_RNG_PROTOCOL in its firmware. Now that we no longer misidentify
small KASLR offsets as randomization being enabled, we can drop the
explicit check for ThunderX as well, given that KASLR is known to be
unavailable on these systems.

Note that we never enable KPTI on these systems, in spite of what this
function returns. The only penalty for getting it wrong (i.e., returning
true here on a ThunderX system) is that we will end up using non-global
mappings for the kernel pointlessly.

Signed-off-by: Ard Biesheuvel <ardb at kernel.org>
---
 arch/arm64/kernel/cpufeature.c | 12 ------------
 1 file changed, 12 deletions(-)

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 22e3604aee02..af46ca0da994 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1550,18 +1550,6 @@ bool kaslr_requires_kpti(void)
 			return false;
 	}
 
-	/*
-	 * Systems affected by Cavium erratum 24756 are incompatible
-	 * with KPTI.
-	 */
-	if (IS_ENABLED(CONFIG_CAVIUM_ERRATUM_27456)) {
-		extern const struct midr_range cavium_erratum_27456_cpus[];
-
-		if (is_midr_in_range_list(read_cpuid_id(),
-					  cavium_erratum_27456_cpus))
-			return false;
-	}
-
 	return kaslr_enabled();
 }
 
-- 
2.35.1