x86, fpu: split FPU state from task struct - v5

Split the FPU save area from the task struct. This allows easy migration
of FPU context, and it's generally cleaner. It also allows the following
two optimizations:

1) only allocate when the application actually uses FPU, so in the first
lazy FPU trap. This could save memory for non-fpu using apps. Next patch
does this lazy allocation.

2) allocate the right size for the actual cpu rather than 512 bytes always.
Patches enabling xsave/xrstor support (coming shortly) will take advantage
of this.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 1 insertions, 1 deletions

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 4c13b1406c70..b795e831afd6 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -682,7 +682,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 
         /* we're going to use this soon, after a few expensive things */
         if (next_p->fpu_counter>5)
-                prefetch(&next->i387.fxsave);
+                prefetch(next->xstate);
 
         /*
          * Reload esp0, LDT and the page table pointer: