x86/fpu: Split an fpstate_alloc_init() function out of init_fpu()

[mirror_ubuntu-artful-kernel.git] / arch / x86 / kernel / i387.c

diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
index 29251f5668b1c84f3712b78de222cd464829281d..56b6e726fb60cec9fbb4228f98d6ad7058e26583 100644 (file)
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -246,6 +246,37 @@ void fpu_finit(struct fpu *fpu)
 }
 EXPORT_SYMBOL_GPL(fpu_finit);
 
+/*
+ * Allocate the backing store for the current task's FPU registers
+ * and initialize the registers themselves as well.
+ *
+ * Can fail.
+ */
+int fpstate_alloc_init(struct task_struct *curr)
+{
+       int ret;
+
+       if (WARN_ON_ONCE(curr != current))
+               return -EINVAL;
+       if (WARN_ON_ONCE(curr->flags & PF_USED_MATH))
+               return -EINVAL;
+
+       /*
+        * Memory allocation at the first usage of the FPU and other state.
+        */
+       ret = fpu_alloc(&curr->thread.fpu);
+       if (ret)
+               return ret;
+
+       fpu_finit(&curr->thread.fpu);
+
+       /* Safe to do for the current task: */
+       curr->flags |= PF_USED_MATH;
+
+       return 0;
+}
+EXPORT_SYMBOL_GPL(fpstate_alloc_init);
+
 /*
  * The _current_ task is using the FPU for the first time
  * so initialize it and set the mxcsr to its default