4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
[ Upstream commit 4253b0e0627ee3461e64c2495c616f1c8f6b127b ]
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@xxxxxxxxxxxxxxx # 4.16
Fixes: d424986f1d ("s390: add sysfs attributes for spectre")
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/s390/kernel/Makefile | 1 +
arch/s390/kernel/nospec-branch.c | 18 ------------------
arch/s390/kernel/nospec-sysfs.c | 21 +++++++++++++++++++++
3 files changed, 22 insertions(+), 18 deletions(-)
create mode 100644 arch/s390/kernel/nospec-sysfs.c
--- a/arch/s390/kernel/Makefile
+++ b/arch/s390/kernel/Makefile
@@ -63,6 +63,7 @@ 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
--- a/arch/s390/kernel/nospec-branch.c
+++ b/arch/s390/kernel/nospec-branch.c
@@ -44,24 +44,6 @@ 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);
--- /dev/null
+++ b/arch/s390/kernel/nospec-sysfs.c
@@ -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");
+}
