From d768bd892fc8f066cd3aa000eb1867bcf32db0ee Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Tue, 16 Jan 2018 07:11:45 +0100 Subject: s390: add options to change branch prediction behaviour for the kernel Add the PPA instruction to the system entry and exit path to switch the kernel to a different branch prediction behaviour. The instructions are added via CPU alternatives and can be disabled with the "nospec" or the "nobp=0" kernel parameter. If the default behaviour selected with CONFIG_KERNEL_NOBP is set to "n" then the "nobp=1" parameter can be used to enable the changed kernel branch prediction. Acked-by: Cornelia Huck Signed-off-by: Martin Schwidefsky --- arch/s390/include/asm/processor.h | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/s390/include/asm') diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h index bfbfad482289..5f37f9ceef5e 100644 --- a/arch/s390/include/asm/processor.h +++ b/arch/s390/include/asm/processor.h @@ -91,6 +91,7 @@ void cpu_detect_mhz_feature(void); extern const struct seq_operations cpuinfo_op; extern int sysctl_ieee_emulation_warnings; extern void execve_tail(void); +extern void __bpon(void); /* * User space process size: 2GB for 31 bit, 4TB or 8PT for 64 bit. -- cgit v1.2.3