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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2018-01-16 09:11:45 +0300
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2018-02-05 15:49:17 +0300
commitd768bd892fc8f066cd3aa000eb1867bcf32db0ee (patch)
tree73856bebc552b175d71bef6859824d7ca8d8e051 /arch/s390/include/asm/processor.h
parentcf1489984641369611556bf00c48f945c77bcf02 (diff)
downloadlinux-d768bd892fc8f066cd3aa000eb1867bcf32db0ee.tar.xz
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 <cohuck@redhat.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/include/asm/processor.h')
-rw-r--r--arch/s390/include/asm/processor.h1
1 files changed, 1 insertions, 0 deletions
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.