sh: Fix up DSP context save/restore.

There were a number of issues with the DSP context save/restore code,
mostly left-over relics from when it was introduced on SH3-DSP with
little follow-up testing, resulting in things like task_pt_dspregs()
referencing incorrect state on the stack.

This follows the MIPS convention of tracking the DSP state in the
thread_struct and handling the state save/restore in switch_to() and
finish_arch_switch() respectively. The regset interface is also updated,
which allows us to finally be rid of task_pt_dspregs() and the special
cased task_pt_regs().

Signed-off-by: Michael Trimarchi <michael@evidence.eu.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 13 insertions, 1 deletions

diff --git a/arch/sh/kernel/process_32.c b/arch/sh/kernel/process_32.c
index ddafbbbab2ab..0747fabd73a7 100644
--- a/arch/sh/kernel/process_32.c
+++ b/arch/sh/kernel/process_32.c
@@ -176,14 +176,26 @@ int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
 {
         struct thread_info *ti = task_thread_info(p);
         struct pt_regs *childregs;
-#if defined(CONFIG_SH_FPU)
+#if defined(CONFIG_SH_FPU) || defined(CONFIG_SH_DSP)
         struct task_struct *tsk = current;
+#endif
 
+#if defined(CONFIG_SH_FPU)
         unlazy_fpu(tsk, regs);
         p->thread.fpu = tsk->thread.fpu;
         copy_to_stopped_child_used_math(p);
 #endif
 
+#if defined(CONFIG_SH_DSP)
+        if (is_dsp_enabled(tsk)) {
+                /* We can use the __save_dsp or just copy the struct:
+                 * __save_dsp(p);
+                 * p->thread.dsp_status.status |= SR_DSP
+                 */
+                p->thread.dsp_status = tsk->thread.dsp_status;
+        }
+#endif
+
         childregs = task_pt_regs(p);
         *childregs = *regs;