ARM: VFP: re-initialize VFP coprocessor access enables on CPU hotplug
We can not guarantee that VFP will be enabled when CPU hotplug brings
a CPU back online from a reset state. Add a hotplug CPU notifier to
ensure that the VFP coprocessor access is enabled whenever a CPU comes
back online.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index 8063a32..0797cb5 100644
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -10,9 +10,12 @@
*/
#include <linux/module.h>
#include <linux/types.h>
+#include <linux/cpu.h>
#include <linux/kernel.h>
+#include <linux/notifier.h>
#include <linux/signal.h>
#include <linux/sched.h>
+#include <linux/smp.h>
#include <linux/init.h>
#include <asm/cputype.h>
@@ -484,7 +487,24 @@
put_cpu();
}
-#include <linux/smp.h>
+/*
+ * VFP hardware can lose all context when a CPU goes offline.
+ * Safely clear our held state when a CPU has been killed, and
+ * re-enable access to VFP when the CPU comes back online.
+ *
+ * Both CPU_DYING and CPU_STARTING are called on the CPU which
+ * is being offlined/onlined.
+ */
+static int vfp_hotplug(struct notifier_block *b, unsigned long action,
+ void *hcpu)
+{
+ if (action == CPU_DYING || action == CPU_DYING_FROZEN) {
+ unsigned int cpu = (long)hcpu;
+ last_VFP_context[cpu] = NULL;
+ } else if (action == CPU_STARTING || action == CPU_STARTING_FROZEN)
+ vfp_enable(NULL);
+ return NOTIFY_OK;
+}
/*
* VFP support code initialisation.
@@ -514,6 +534,8 @@
else if (vfpsid & FPSID_NODOUBLE) {
printk("no double precision support\n");
} else {
+ hotcpu_notifier(vfp_hotplug, 0);
+
smp_call_function(vfp_enable, NULL, 1);
VFP_arch = (vfpsid & FPSID_ARCH_MASK) >> FPSID_ARCH_BIT; /* Extract the architecture version */