From 34d0b02e08470c56a411ba6da1f377bc6da02826 Mon Sep 17 00:00:00 2001 From: Jarkko Sakkinen Date: Thu, 10 May 2012 10:11:38 +0300 Subject: x86, realmode: Fix no cache bits test in reboot_32.S Before the new real-mode code infrastructure %edx was used for testing CD and NW bits with andl in order to decide whether to flush the processor caches or not. The value of cr0 was also stored in %eax, which was later used to set cr0 after masking out lower byte (except TS bit) in order to enter real-mode. In the new real-mode code infrastructure we wanted to keep input parameter in %eax so we are using %edx for both cr0 cases. This has caused regression since andl overwrites the value of %edx. This patch fixes the issue by replacing andl with testl, which is essentially andl without writing result to the register. Special thanks to Paolo Bonzini for noting this and proposing a fix. Reported-and-tested-by: Paolo Bonzini Signed-off-by: Jarkko Sakkinen Link: http://lkml.kernel.org/r/1336633898-23743-1-git-send-email-jarkko.sakkinen@intel.com Signed-off-by: H. Peter Anvin diff --git a/arch/x86/realmode/rm/reboot_32.S b/arch/x86/realmode/rm/reboot_32.S index 8d9bfd1..1140448 100644 --- a/arch/x86/realmode/rm/reboot_32.S +++ b/arch/x86/realmode/rm/reboot_32.S @@ -76,7 +76,7 @@ machine_real_restart_asm16: movl %edx, %cr0 movl %ecx, %cr3 movl %cr0, %edx - andl $0x60000000, %edx /* If no cache bits -> no wbinvd */ + testl $0x60000000, %edx /* If no cache bits -> no wbinvd */ jz 2f wbinvd 2: -- cgit v0.10.2