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>

3 files changed, 136 insertions, 55 deletions

diff --git a/arch/sh/include/asm/processor_32.h b/arch/sh/include/asm/processor_32.h
index efdd78a53b1..9a8714945dc 100644
--- a/arch/sh/include/asm/processor_32.h
+++ b/arch/sh/include/asm/processor_32.h
@@ -58,6 +58,14 @@ asmlinkage void __init sh_cpu_init(void);
 #define SR_FD		0x00008000
 
 /*
+ * DSP structure and data
+ */
+struct sh_dsp_struct {
+	unsigned long dsp_regs[14];
+	long status;
+};
+
+/*
  * FPU structure and data
  */
 
@@ -96,6 +104,11 @@ struct thread_struct {
 
 	/* floating point info */
 	union sh_fpu_union fpu;
+
+#ifdef CONFIG_SH_DSP
+	/* Dsp status information */
+	struct sh_dsp_struct dsp_status;
+#endif
 };
 
 /* Count of active tasks with UBC settings */
diff --git a/arch/sh/include/asm/ptrace.h b/arch/sh/include/asm/ptrace.h
index 81c6568fdb3..d3f6caa936b 100644
--- a/arch/sh/include/asm/ptrace.h
+++ b/arch/sh/include/asm/ptrace.h
@@ -119,16 +119,8 @@ struct task_struct;
 extern void user_enable_single_step(struct task_struct *);
 extern void user_disable_single_step(struct task_struct *);
 
-#ifdef CONFIG_SH_DSP
-#define task_pt_regs(task) \
-	((struct pt_regs *) (task_stack_page(task) + THREAD_SIZE \
-		 - sizeof(struct pt_dspregs)) - 1)
-#define task_pt_dspregs(task) \
-	((struct pt_dspregs *) (task_stack_page(task) + THREAD_SIZE) - 1)
-#else
 #define task_pt_regs(task) \
 	((struct pt_regs *) (task_stack_page(task) + THREAD_SIZE) - 1)
-#endif
 
 static inline unsigned long profile_pc(struct pt_regs *regs)
 {
diff --git a/arch/sh/include/asm/system_32.h b/arch/sh/include/asm/system_32.h
index a726d5d0727..240b31e1142 100644
--- a/arch/sh/include/asm/system_32.h
+++ b/arch/sh/include/asm/system_32.h
@@ -3,59 +3,135 @@
 
 #include <linux/types.h>
 
+#ifdef CONFIG_SH_DSP
+
+#define is_dsp_enabled(tsk)						\
+	(!!(tsk->thread.dsp_status.status & SR_DSP))
+
+#define __restore_dsp(tsk)						\
+do {									\
+	register u32 *__ts2 __asm__ ("r2") =				\
+			(u32 *)&tsk->thread.dsp_status;			\
+	__asm__ __volatile__ (						\
+		".balign 4\n\t"						\
+		"movs.l	@r2+, a1\n\t"					\
+		"movs.l	@r2+, a0g\n\t"					\
+		"movs.l	@r2+, a1g\n\t"					\
+		"movs.l	@r2+, m0\n\t"					\
+		"movs.l	@r2+, m1\n\t"					\
+		"movs.l	@r2+, a0\n\t"					\
+		"movs.l	@r2+, x0\n\t"					\
+		"movs.l	@r2+, x1\n\t"					\
+		"movs.l	@r2+, y0\n\t"					\
+		"movs.l	@r2+, y1\n\t"					\
+		"lds.l	@r2+, dsr\n\t"					\
+		"ldc.l	@r2+, rs\n\t"					\
+		"ldc.l	@r2+, re\n\t"					\
+		"ldc.l	@r2+, mod\n\t"					\
+		: : "r" (__ts2));					\
+} while (0)
+
+
+#define __save_dsp(tsk)							\
+do {									\
+	register u32 *__ts2 __asm__ ("r2") =				\
+			(u32 *)&tsk->thread.dsp_status + 14;		\
+									\
+	__asm__ __volatile__ (						\
+		".balign 4\n\t"						\
+		"stc.l	mod, @-r2\n\t"				\
+		"stc.l	re, @-r2\n\t"					\
+		"stc.l	rs, @-r2\n\t"					\
+		"sts.l	dsr, @-r2\n\t"				\
+		"sts.l	y1, @-r2\n\t"					\
+		"sts.l	y0, @-r2\n\t"					\
+		"sts.l	x1, @-r2\n\t"					\
+		"sts.l	x0, @-r2\n\t"					\
+		"sts.l	a0, @-r2\n\t"					\
+		".word	0xf653		! movs.l	a1, @-r2\n\t"	\
+		".word	0xf6f3		! movs.l	a0g, @-r2\n\t"	\
+		".word	0xf6d3		! movs.l	a1g, @-r2\n\t"	\
+		".word	0xf6c3		! movs.l        m0, @-r2\n\t"	\
+		".word	0xf6e3		! movs.l        m1, @-r2\n\t"	\
+		: : "r" (__ts2));					\
+} while (0)
+
+#else
+
+#define is_dsp_enabled(tsk)	(0)
+#define __save_dsp(tsk)		do { } while (0)
+#define __restore_dsp(tsk)	do { } while (0)
+#endif
+
 struct task_struct *__switch_to(struct task_struct *prev,
 				struct task_struct *next);
 
 /*
  *	switch_to() should switch tasks to task nr n, first
  */
-#define switch_to(prev, next, last)					\
-do {									\
-	register u32 *__ts1 __asm__ ("r1") = (u32 *)&prev->thread.sp;	\
-	register u32 *__ts2 __asm__ ("r2") = (u32 *)&prev->thread.pc;	\
-	register u32 *__ts4 __asm__ ("r4") = (u32 *)prev;		\
-	register u32 *__ts5 __asm__ ("r5") = (u32 *)next;		\
-	register u32 *__ts6 __asm__ ("r6") = (u32 *)&next->thread.sp;	\
-	register u32 __ts7 __asm__ ("r7") = next->thread.pc;		\
-	struct task_struct *__last;					\
-									\
-	__asm__ __volatile__ (						\
-		".balign 4\n\t"						\
-		"stc.l	gbr, @-r15\n\t"					\
-		"sts.l	pr, @-r15\n\t"					\
-		"mov.l	r8, @-r15\n\t"					\
-		"mov.l	r9, @-r15\n\t"					\
-		"mov.l	r10, @-r15\n\t"					\
-		"mov.l	r11, @-r15\n\t"					\
-		"mov.l	r12, @-r15\n\t"					\
-		"mov.l	r13, @-r15\n\t"					\
-		"mov.l	r14, @-r15\n\t"					\
-		"mov.l	r15, @r1\t! save SP\n\t"			\
-		"mov.l	@r6, r15\t! change to new stack\n\t"		\
-		"mova	1f, %0\n\t"					\
-		"mov.l	%0, @r2\t! save PC\n\t"				\
-		"mov.l	2f, %0\n\t"					\
-		"jmp	@%0\t! call __switch_to\n\t"			\
-		" lds	r7, pr\t!  with return to new PC\n\t"		\
-		".balign	4\n"					\
-		"2:\n\t"						\
-		".long	__switch_to\n"					\
-		"1:\n\t"						\
-		"mov.l	@r15+, r14\n\t"					\
-		"mov.l	@r15+, r13\n\t"					\
-		"mov.l	@r15+, r12\n\t"					\
-		"mov.l	@r15+, r11\n\t"					\
-		"mov.l	@r15+, r10\n\t"					\
-		"mov.l	@r15+, r9\n\t"					\
-		"mov.l	@r15+, r8\n\t"					\
-		"lds.l	@r15+, pr\n\t"					\
-		"ldc.l	@r15+, gbr\n\t"					\
-		: "=z" (__last)						\
-		: "r" (__ts1), "r" (__ts2), "r" (__ts4),		\
-		  "r" (__ts5), "r" (__ts6), "r" (__ts7)			\
-		: "r3", "t");						\
-									\
-	last = __last;							\
+#define switch_to(prev, next, last)				\
+do {								\
+	register u32 *__ts1 __asm__ ("r1");			\
+	register u32 *__ts2 __asm__ ("r2");			\
+	register u32 *__ts4 __asm__ ("r4");			\
+	register u32 *__ts5 __asm__ ("r5");			\
+	register u32 *__ts6 __asm__ ("r6");			\
+	register u32 __ts7 __asm__ ("r7");			\
+	struct task_struct *__last;				\
+								\
+	if (is_dsp_enabled(prev))				\
+		__save_dsp(prev);				\
+								\
+	__ts1 = (u32 *)&prev->thread.sp;			\
+	__ts2 = (u32 *)&prev->thread.pc;			\
+	__ts4 = (u32 *)prev;					\
+	__ts5 = (u32 *)next;					\
+	__ts6 = (u32 *)&next->thread.sp;			\
+	__ts7 = next->thread.pc;				\
+								\
+	__asm__ __volatile__ (					\
+		".balign 4\n\t"					\
+		"stc.l	gbr, @-r15\n\t"				\
+		"sts.l	pr, @-r15\n\t"				\
+		"mov.l	r8, @-r15\n\t"				\
+		"mov.l	r9, @-r15\n\t"				\
+		"mov.l	r10, @-r15\n\t"				\
+		"mov.l	r11, @-r15\n\t"				\
+		"mov.l	r12, @-r15\n\t"				\
+		"mov.l	r13, @-r15\n\t"				\
+		"mov.l	r14, @-r15\n\t"				\
+		"mov.l	r15, @r1\t! save SP\n\t"		\
+		"mov.l	@r6, r15\t! change to new stack\n\t"	\
+		"mova	1f, %0\n\t"				\
+		"mov.l	%0, @r2\t! save PC\n\t"			\
+		"mov.l	2f, %0\n\t"				\
+		"jmp	@%0\t! call __switch_to\n\t"		\
+		" lds	r7, pr\t!  with return to new PC\n\t"	\
+		".balign	4\n"				\
+		"2:\n\t"					\
+		".long	__switch_to\n"				\
+		"1:\n\t"					\
+		"mov.l	@r15+, r14\n\t"				\
+		"mov.l	@r15+, r13\n\t"				\
+		"mov.l	@r15+, r12\n\t"				\
+		"mov.l	@r15+, r11\n\t"				\
+		"mov.l	@r15+, r10\n\t"				\
+		"mov.l	@r15+, r9\n\t"				\
+		"mov.l	@r15+, r8\n\t"				\
+		"lds.l	@r15+, pr\n\t"				\
+		"ldc.l	@r15+, gbr\n\t"				\
+		: "=z" (__last)					\
+		: "r" (__ts1), "r" (__ts2), "r" (__ts4),	\
+		  "r" (__ts5), "r" (__ts6), "r" (__ts7)		\
+		: "r3", "t");					\
+								\
+	last = __last;						\
+} while (0)
+
+#define finish_arch_switch(prev)				\
+do {								\
+	if (is_dsp_enabled(prev))				\
+		__restore_dsp(prev);				\
 } while (0)
 
 #define __uses_jump_to_uncached \