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The fpu_init() register initialization has been replaced by xstate setup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, 48 insertions, 32 deletions

diff --git a/arch/sh/kernel/cpu/init.c b/arch/sh/kernel/cpu/init.c
index 89b4b76c0d76..2e23422280a7 100644
--- a/arch/sh/kernel/cpu/init.c
+++ b/arch/sh/kernel/cpu/init.c
@@ -28,18 +28,30 @@
 #include <asm/ubc.h>
 #endif
 
+#ifdef CONFIG_SH_FPU
+#define cpu_has_fpu     1
+#else
+#define cpu_has_fpu     0
+#endif
+
+#ifdef CONFIG_SH_DSP
+#define cpu_has_dsp     1
+#else
+#define cpu_has_dsp     0
+#endif
+
 /*
  * Generic wrapper for command line arguments to disable on-chip
  * peripherals (nofpu, nodsp, and so forth).
  */
-#define onchip_setup(x)                         \
-static int x##_disabled __initdata = 0;         \
-                                                \
-static int __init x##_setup(char *opts)         \
-{                                               \
-        x##_disabled = 1;                       \
-        return 1;                               \
-}                                               \
+#define onchip_setup(x)                                 \
+static int x##_disabled __initdata = !cpu_has_##x;      \
+                                                        \
+static int __init x##_setup(char *opts)                 \
+{                                                       \
+        x##_disabled = 1;                               \
+        return 1;                                       \
+}                                                       \
 __setup("no" __stringify(x), x##_setup);
 
 onchip_setup(fpu);
@@ -207,6 +219,18 @@ static void detect_cache_shape(void)
                 l2_cache_shape = -1; /* No S-cache */
 }
 
+static void __init fpu_init(void)
+{
+        /* Disable the FPU */
+        if (fpu_disabled && (current_cpu_data.flags & CPU_HAS_FPU)) {
+                printk("FPU Disabled\n");
+                current_cpu_data.flags &= ~CPU_HAS_FPU;
+        }
+
+        disable_fpu();
+        clear_used_math();
+}
+
 #ifdef CONFIG_SH_DSP
 static void __init release_dsp(void)
 {
@@ -244,9 +268,17 @@ static void __init dsp_init(void)
         if (sr & SR_DSP)
                 current_cpu_data.flags |= CPU_HAS_DSP;
 
+        /* Disable the DSP */
+        if (dsp_disabled && (current_cpu_data.flags & CPU_HAS_DSP)) {
+                printk("DSP Disabled\n");
+                current_cpu_data.flags &= ~CPU_HAS_DSP;
+        }
+
         /* Now that we've determined the DSP status, clear the DSP bit. */
         release_dsp();
 }
+#else
+static inline void __init dsp_init(void) { }
 #endif /* CONFIG_SH_DSP */
 
 /**
@@ -302,18 +334,8 @@ asmlinkage void __init sh_cpu_init(void)
                 detect_cache_shape();
         }
 
-        /* Disable the FPU */
-        if (fpu_disabled) {
-                printk("FPU Disabled\n");
-                current_cpu_data.flags &= ~CPU_HAS_FPU;
-        }
-
-        /* FPU initialization */
-        disable_fpu();
-        if ((current_cpu_data.flags & CPU_HAS_FPU)) {
-                current_thread_info()->status &= ~TS_USEDFPU;
-                clear_used_math();
-        }
+        fpu_init();
+        dsp_init();
 
         /*
          * Initialize the per-CPU ASID cache very early, since the
@@ -321,18 +343,12 @@ asmlinkage void __init sh_cpu_init(void)
          */
         current_cpu_data.asid_cache = NO_CONTEXT;
 
-#ifdef CONFIG_SH_DSP
-        /* Probe for DSP */
-        dsp_init();
-
-        /* Disable the DSP */
-        if (dsp_disabled) {
-                printk("DSP Disabled\n");
-                current_cpu_data.flags &= ~CPU_HAS_DSP;
-                release_dsp();
-        }
-#endif
-
         speculative_execution_init();
         expmask_init();
+
+        /*
+         * Boot processor to setup the FP and extended state context info.
+         */
+        if (raw_smp_processor_id() == 0)
+                init_thread_xstate();
 }