Blackfin arch: disable pthread stack check for SMP at runtime

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>

arch/blackfin/include/asm/l1layout.h

@@ -8,6 +8,7 @@
 
 #include <asm/blackfin.h>
 
+#ifndef CONFIG_SMP
 #ifndef __ASSEMBLY__
 
 /* Data that is "mapped" into the process VM at the start of the L1 scratch
@@ -28,5 +29,6 @@ struct l1_scratch_task_info
 						get_l1_scratch_start())
 
 #endif
+#endif
 
 #endif

arch/blackfin/include/asm/processor.h

@@ -65,6 +65,7 @@ struct thread_struct {
  * pass the data segment into user programs if it exists,
  * it can't hurt anything as far as I can tell
  */
+#ifndef CONFIG_SMP
 #define start_thread(_regs, _pc, _usp)					\
 do {									\
 	set_fs(USER_DS);						\
@@ -78,6 +79,16 @@ do {									\
 		sizeof(*L1_SCRATCH_TASK_INFO));				\
 	wrusp(_usp);							\
 } while(0)
+#else
+#define start_thread(_regs, _pc, _usp)					\
+do {									\
+	set_fs(USER_DS);						\
+	(_regs)->pc = (_pc);						\
+	if (current->mm)						\
+		(_regs)->p5 = current->mm->start_data;			\
+	wrusp(_usp);							\
+} while (0)
+#endif
 
 /* Forward declaration, a strange C thing */
 struct task_struct;

arch/blackfin/include/asm/system.h

@@ -197,6 +197,7 @@ static inline unsigned long __xchg(unsigned long x, volatile void *ptr,
 
 asmlinkage struct task_struct *resume(struct task_struct *prev, struct task_struct *next);
 
+#ifndef CONFIG_SMP
 #define switch_to(prev,next,last) \
 do {    \
 	memcpy (&task_thread_info(prev)->l1_task_info, L1_SCRATCH_TASK_INFO, \
@@ -205,5 +206,11 @@ do {    \
 		sizeof *L1_SCRATCH_TASK_INFO); \
 	(last) = resume (prev, next);   \
 } while (0)
+#else
+#define switch_to(prev, next, last) \
+do {    \
+	(last) = resume(prev, next);   \
+} while (0)
+#endif
 
 #endif	/* _BLACKFIN_SYSTEM_H */

arch/blackfin/include/asm/thread_info.h

@@ -63,7 +63,9 @@ struct thread_info {
 	int preempt_count;	/* 0 => preemptable, <0 => BUG */
 	mm_segment_t addr_limit;	/* address limit */
 	struct restart_block restart_block;
+#ifndef CONFIG_SMP
 	struct l1_scratch_task_info l1_task_info;
+#endif
 };
 
 /*