s390: move spectre sysfs attribute code

BugLink: http://bugs.launchpad.net/bugs/1783418
[ 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@vger.kernel.org # 4.16
Fixes: d424986f1d ("s390: add sysfs attributes for spectre")
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/arch/s390/kernel/Makefile b/arch/s390/kernel/Makefile
index 6701abad9ac2a7eb7f94f1aa30af02751cc4d349..ec5bac79ead1d9a9e9b784069ddb113be04ce5dc 100644 (file)
--- a/arch/s390/kernel/Makefile
+++ b/arch/s390/kernel/Makefile
@@ -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

diff --git a/arch/s390/kernel/nospec-branch.c b/arch/s390/kernel/nospec-branch.c
index f236ce8757e8d4e0334859ebc59e53c2fafff727..834cf29f25999298aa9462e2382971090356fdae 100644 (file)
--- a/arch/s390/kernel/nospec-branch.c
+++ b/arch/s390/kernel/nospec-branch.c
@@ -43,24 +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);

diff --git a/arch/s390/kernel/nospec-sysfs.c b/arch/s390/kernel/nospec-sysfs.c
new file mode 100644 (file)
index 0000000..8affad5
--- /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");
+}