From 192d1dccbfc5b901b66527df9df80304693cf06e Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Thu, 29 Sep 2016 12:48:11 -0700 Subject: [PATCH] x86/boot: Fix another __read_cr4() case on 486 The condition for reading CR4 was wrong: there are some CPUs with CPUID but not CR4. Rather than trying to make the condition exact, use __read_cr4_safe(). Fixes: 18bc7bd523e0 ("x86/boot: Synchronize trampoline_cr4_features and mmu_cr4_features directly") Reported-by: david@saggiorato.net Signed-off-by: Andy Lutomirski Reviewed-by: Borislav Petkov Cc: Brian Gerst Link: http://lkml.kernel.org/r/8c453a61c4f44ab6ff43c29780ba04835234d2e5.1475178369.git.luto@kernel.org Signed-off-by: Thomas Gleixner --- arch/x86/kernel/setup.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index 0fa60f5f5a16..98c9cd6f3b5d 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -1137,9 +1137,7 @@ void __init setup_arch(char **cmdline_p) * auditing all the early-boot CR4 manipulation would be needed to * rule it out. */ - if (boot_cpu_data.cpuid_level >= 0) - /* A CPU has %cr4 if and only if it has CPUID. */ - mmu_cr4_features = __read_cr4(); + mmu_cr4_features = __read_cr4_safe(); memblock_set_current_limit(get_max_mapped()); -- 2.20.1