From 8dd0ee651d8aefdc2d8ae0fcc9c68dfc943c9e4c Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Mon, 5 Jun 2017 11:40:23 +0100 Subject: [PATCH] arm64: cpufeature: Fix CPU_OUT_OF_SPEC taint for uniform systems Commit 3fde2999fac5 ("arm64: cpufeature: Don't dump useless backtrace on CPU_OUT_OF_SPEC") changed the cpufeature detection code to use add_taint instead of WARN_TAINT_ONCE when detecting a heterogeneous system with mismatched feature support. Unfortunately, this resulted in all systems getting the taint, regardless of any feature mismatch. This patch fixes the problem by conditionalising the taint on detecting a feature mismatch. Acked-by: Mark Rutland Reported-by: Heiner Kallweit Signed-off-by: Will Deacon --- arch/arm64/kernel/cpufeature.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 22f554320581..55d5c72a507d 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -639,8 +639,10 @@ void update_cpu_features(int cpu, * Mismatched CPU features are a recipe for disaster. Don't even * pretend to support them. */ - pr_warn_once("Unsupported CPU feature variation detected.\n"); - add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK); + if (taint) { + pr_warn_once("Unsupported CPU feature variation detected.\n"); + add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK); + } } u64 read_sanitised_ftr_reg(u32 id) -- GitLab