[PATCH] ARM: vfp: Prevent process migration during vfp_init()

[Hyungwoo Yang]

System crashes if there is process migration during vfp_init() call.

During vfp_init(), if a process which called vfp_enable() is migrated just
after the call, then the process executing the rest of code will access
a VFP unit which is not ENABLED and also smp_call_function() will not work
as it is expected.

This patch prevents accessing VFP unit disabled by preventing migration
and also replaces smp_call_function() with on_each_cpu() to make sure that
no VFP remains disabled.

Signed-off-by: Hyungwoo Yang <hyungwooy@xxxxxxxxxx>
---
 arch/arm/vfp/vfpmodule.c |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index bc683b8..fefa4cb 100644
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -655,7 +655,9 @@ static int __init vfp_init(void)
 {
 	unsigned int vfpsid;
 	unsigned int cpu_arch = cpu_architecture();
-
+#ifdef CONFIG_SMP
+	preempt_disable();
+#endif
 	if (cpu_arch >= CPU_ARCH_ARMv6)
 		vfp_enable(NULL);

@@ -669,6 +671,9 @@ static int __init vfp_init(void)
 	vfpsid = fmrx(FPSID);
 	barrier();
 	vfp_vector = vfp_null_entry;
+#ifdef CONFIG_SMP
+	preempt_enable();
+#endif

 	printk(KERN_INFO "VFP support v0.3: ");
 	if (VFP_arch)
@@ -678,7 +683,7 @@ static int __init vfp_init(void)
 	} else {
 		hotcpu_notifier(vfp_hotplug, 0);

-		smp_call_function(vfp_enable, NULL, 1);
+		on_each_cpu(vfp_enable, NULL, 1);

 		VFP_arch = (vfpsid & FPSID_ARCH_MASK) >> FPSID_ARCH_BIT;  /*
Extract the architecture version */
 		printk("implementor %02x architecture %d part %02x variant %x rev %x\n",
-- 
1.7.0.4
--
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