sh: Move over to dynamically allocated FPU context.

This follows the x86 xstate changes and implements a task_xstate slab
cache that is dynamically sized to match one of hard FP/soft FP/FPU-less.

This also tidies up and consolidates some of the SH-2A/SH-4 FPU
fragmentation. Now fpu state restorers are commonly defined, with the
init_fpu()/fpu_init() mess reworked to follow the x86 convention.
The fpu_init() register initialization has been replaced by xstate setup
followed by writing out to hardware via the standard restore path.

As init_fpu() now performs a slab allocation a secondary lighterweight
restorer is also introduced for the context switch.

In the future the DSP state will be rolled in here, too.

More work remains for math emulation and the SH-5 FPU, which presently
uses its own special (UP-only) interfaces.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 10 insertions, 6 deletions

diff --git a/arch/sh/include/asm/processor_32.h b/arch/sh/include/asm/processor_32.h
index 50b8c9c3fa4c..a359898206e8 100644
--- a/arch/sh/include/asm/processor_32.h
+++ b/arch/sh/include/asm/processor_32.h
@@ -90,11 +90,15 @@ struct sh_fpu_soft_struct {
 	unsigned long entry_pc;
 };
 
-union sh_fpu_union {
-	struct sh_fpu_hard_struct hard;
-	struct sh_fpu_soft_struct soft;
+union thread_xstate {
+	struct sh_fpu_hard_struct hardfpu;
+	struct sh_fpu_soft_struct softfpu;
 };
 
+extern unsigned int xstate_size;
+extern void free_thread_xstate(struct task_struct *);
+extern struct kmem_cache *task_xstate_cachep;
+
 struct thread_struct {
 	/* Saved registers when thread is descheduled */
 	unsigned long sp;
@@ -103,13 +107,13 @@ struct thread_struct {
 	/* Hardware debugging registers */
 	unsigned long ubc_pc;
 
-	/* floating point info */
-	union sh_fpu_union fpu;
-
 #ifdef CONFIG_SH_DSP
 	/* Dsp status information */
 	struct sh_dsp_struct dsp_status;
 #endif
+
+	/* Extended processor state */
+	union thread_xstate *xstate;
 };
 
 /* Count of active tasks with UBC settings */