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s390: move spectre sysfs attribute code 

The nospec-branch.c file is compiled without the gcc options to
generate expoline thunks. The return branch of the sysfs show
functions cpu_show_spectre_v1 and cpu_show_spectre_v2 is an indirect
branch as well. These need to be compiled with expolines.

Move the sysfs functions for spectre reporting to a separate file
and loose an '.' for one of the messages.

Cc: stable@vger.kernel.org # 4.16
Fixes: d424986f1d ("s390: add sysfs attributes for spectre")
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky 2018-04-24 08:23:54 +02:00
parent c50c84c3ac
commit 4253b0e062
3 changed files with 22 additions and 19 deletions
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1
arch/s390/kernel/Makefile
View File

@ -65,6 +65,7 @@ obj-y += nospec-branch.o
extra-y += head.o head64.o vmlinux.lds
obj-$(CONFIG_SYSFS) += nospec-sysfs.o
CFLAGS_REMOVE_nospec-branch.o += $(CC_FLAGS_EXPOLINE)
obj-$(CONFIG_MODULES) += module.o

19
arch/s390/kernel/nospec-branch.c
View File

@ -1,7 +1,6 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/module.h>
#include <linux/device.h>
#include <linux/cpu.h>
#include <asm/nospec-branch.h>
static int __init nobp_setup_early(char *str)
@ -44,24 +43,6 @@ static int __init nospec_report(void)
}
arch_initcall(nospec_report);
#ifdef CONFIG_SYSFS
ssize_t cpu_show_spectre_v1(struct device *dev,
struct device_attribute *attr, char *buf)
{
return sprintf(buf, "Mitigation: __user pointer sanitization\n");
}
ssize_t cpu_show_spectre_v2(struct device *dev,
struct device_attribute *attr, char *buf)
{
if (IS_ENABLED(CC_USING_EXPOLINE) && !nospec_disable)
return sprintf(buf, "Mitigation: execute trampolines\n");
if (__test_facility(82, S390_lowcore.alt_stfle_fac_list))
return sprintf(buf, "Mitigation: limited branch prediction.\n");
return sprintf(buf, "Vulnerable\n");
}
#endif
#ifdef CONFIG_EXPOLINE
int nospec_disable = IS_ENABLED(CONFIG_EXPOLINE_OFF);

21
arch/s390/kernel/nospec-sysfs.c Normal file
View File

@ -0,0 +1,21 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/device.h>
#include <linux/cpu.h>
#include <asm/facility.h>
#include <asm/nospec-branch.h>
ssize_t cpu_show_spectre_v1(struct device *dev,
struct device_attribute *attr, char *buf)
{
return sprintf(buf, "Mitigation: __user pointer sanitization\n");
}
ssize_t cpu_show_spectre_v2(struct device *dev,
struct device_attribute *attr, char *buf)
{
if (IS_ENABLED(CC_USING_EXPOLINE) && !nospec_disable)
return sprintf(buf, "Mitigation: execute trampolines\n");
if (__test_facility(82, S390_lowcore.alt_stfle_fac_list))
return sprintf(buf, "Mitigation: limited branch prediction\n");
return sprintf(buf, "Vulnerable\n");
}