[PATCH 4.9 27/31] cpu/speculation: Uninline and export CPU mitigations helpers

Greg Kroah-Hartman
2019-11-15T06:23:20Z

From: Tyler Hicks <tyhicks@canonical.com>

commit 731dc9df975a5da21237a18c3384f811a7a41cc6 upstream.

A kernel module may need to check the value of the "mitigations=" kernel
command line parameter as part of its setup when the module needs
to perform software mitigations for a CPU flaw.

Uninline and export the helper functions surrounding the cpu_mitigations
enum to allow for their usage from a module.

Lastly, privatize the enum and cpu_mitigations variable since the value of
cpu_mitigations can be checked with the exported helper functions.

Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/linux/cpu.h | 25 ++-----------------------
kernel/cpu.c | 27 ++++++++++++++++++++++++++-
2 files changed, 28 insertions(+), 24 deletions(-)

--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -287,28 +287,7 @@ static inline int cpuhp_smt_enable(void)
static inline int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval) { return 0; }
#endif

-/*
- * These are used for a global "mitigations=" cmdline option for toggling
- * optional CPU mitigations.
- */
-enum cpu_mitigations {
- CPU_MITIGATIONS_OFF,
- CPU_MITIGATIONS_AUTO,
- CPU_MITIGATIONS_AUTO_NOSMT,
-};
-
-extern enum cpu_mitigations cpu_mitigations;
-
-/* mitigations=off */
-static inline bool cpu_mitigations_off(void)
-{
- return cpu_mitigations == CPU_MITIGATIONS_OFF;
-}
-
-/* mitigations=auto,nosmt */
-static inline bool cpu_mitigations_auto_nosmt(void)
-{
- return cpu_mitigations == CPU_MITIGATIONS_AUTO_NOSMT;
-}
+extern bool cpu_mitigations_off(void);
+extern bool cpu_mitigations_auto_nosmt(void);

#endif /* _LINUX_CPU_H_ */
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -2235,7 +2235,18 @@ void __init boot_cpu_hotplug_init(void)
this_cpu_write(cpuhp_state.state, CPUHP_ONLINE);
}

-enum cpu_mitigations cpu_mitigations __ro_after_init = CPU_MITIGATIONS_AUTO;
+/*
+ * These are used for a global "mitigations=" cmdline option for toggling
+ * optional CPU mitigations.
+ */
+enum cpu_mitigations {
+ CPU_MITIGATIONS_OFF,
+ CPU_MITIGATIONS_AUTO,
+ CPU_MITIGATIONS_AUTO_NOSMT,
+};
+
+static enum cpu_mitigations cpu_mitigations __ro_after_init =
+ CPU_MITIGATIONS_AUTO;

static int __init mitigations_parse_cmdline(char *arg)
{
@@ -2252,3 +2263,17 @@ static int __init mitigations_parse_cmdl
return 0;
}
early_param("mitigations", mitigations_parse_cmdline);
+
+/* mitigations=off */
+bool cpu_mitigations_off(void)
+{
+ return cpu_mitigations == CPU_MITIGATIONS_OFF;
+}
+EXPORT_SYMBOL_GPL(cpu_mitigations_off);
+
+/* mitigations=auto,nosmt */
+bool cpu_mitigations_auto_nosmt(void)
+{
+ return cpu_mitigations == CPU_MITIGATIONS_AUTO_NOSMT;
+}
+EXPORT_SYMBOL_GPL(cpu_mitigations_auto_nosmt);