From 3cc070c1c81948b33ebe2ea68cd39307ce2b312d Mon Sep 17 00:00:00 2001 From: afzal mohammed Date: Thu, 23 Mar 2017 13:49:32 +0100 Subject: [PATCH] ARM: 8665/1: nommu: access ID_PFR1 only if CPUID scheme Greg upon trying to boot no-MMU Kernel on ARM926EJ reported boot failure. He root caused it to ID_PFR1 access introduced by the commit mentioned in the fixes tag below. All CP15 processors need not have processor feature registers, only for architectures defined by CPUID scheme would have it. Hence check for it before accessing processor feature register, ID_PFR1. Fixes: f8300a0b5de0 ("ARM: 8647/2: nommu: dynamic exception base address setting") Reported-by: Greg Ungerer Signed-off-by: afzal mohammed Tested-by: Greg Ungerer Signed-off-by: Russell King --- arch/arm/mm/nommu.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/arm/mm/nommu.c b/arch/arm/mm/nommu.c index 3b5c7aaf9c76..33a45bd96860 100644 --- a/arch/arm/mm/nommu.c +++ b/arch/arm/mm/nommu.c @@ -303,7 +303,10 @@ static inline void set_vbar(unsigned long val) */ static inline bool security_extensions_enabled(void) { - return !!cpuid_feature_extract(CPUID_EXT_PFR1, 4); + /* Check CPUID Identification Scheme before ID_PFR1 read */ + if ((read_cpuid_id() & 0x000f0000) == 0x000f0000) + return !!cpuid_feature_extract(CPUID_EXT_PFR1, 4); + return 0; } static unsigned long __init setup_vectors_base(void) -- 2.20.1