[v7,04/33] arm64: kaslr: drop special case for ThunderX in kaslr_requires_kpti()

Commit Message

Ard Biesheuvel Nov. 11, 2022, 5:11 p.m. UTC

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.

Note that we never enable KPTI on these systems, in spite of what this
function returns. However, using non-global mappings for code regions is
what tickles the erratum on these cores, regardless of whether KPTI is
enabled or not, so non-global mappings should simply never be used here.

Signed-off-by: Ard Biesheuvel <[e-mail]>
---
 arch/arm64/kernel/cpufeature.c | 12 ------------
 1 file changed, 12 deletions(-)

Patch

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index ded7684b0a304edc..fdbae2320b466d98 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1608,18 +1608,6 @@  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();
 }