Optimizations to _NewContext() and _NewContextInternal()

Since the address of the new context is known before _NewContext() is invoked
(due to it being passed a properly aligned stack), there is no longer any
need for _NewContext to return the pointer to the context.

Furthermore, as a direct result of the properly aligned stack, the pointer to
the new context does not need to be passed as a separate parameter since it
will always match the passed stack pointer.

Change-Id: Ie57a9c4ad17f6f13e8b3f659cd701d4f8950ea97
Signed-off-by: Peter Mitsis <peter.mitsis@windriver.com>

arch/arc/core/context.c

@@ -108,7 +108,7 @@ static ALWAYS_INLINE void context_monitor_init(struct s_CCS *pCcs /* context */
  * RETURNS: N/A
  */
 
-void *_NewContext(
+void _NewContext(
 	char *pStackMem,       /* pointer to aligned stack memory */
 	unsigned stackSize,    /* stack size in bytes */
 	_ContextEntry pEntry,  /* context (thread) entry point routine */
@@ -166,6 +166,4 @@ void *_NewContext(
 	/* initial values in all other registers/CCS entries are irrelevant */
 
 	CONTEXT_MONITOR_INIT(pCcs);
-
-	return pCcs;
 }

arch/arc/include/nanok.h

@@ -265,7 +265,7 @@ static ALWAYS_INLINE int _IS_IN_ISR(void)
 }
 
 extern void _insert_ccs(tCCS **, tCCS *);
-extern void *_NewContext(char *, unsigned, _ContextEntry,
+extern void _NewContext(char *, unsigned, _ContextEntry,
 						_ContextArg, _ContextArg, _ContextArg,
 						int, unsigned);
 

arch/arm/core/nanocontext.c

@@ -102,7 +102,7 @@ static ALWAYS_INLINE void _context_monitor_init(struct s_CCS *pCcs /* context */
 * RETURNS: N/A
 */
 
-void *_NewContext(
+void _NewContext(
 	char *pStackMem,      /* aligned stack memory */
 	unsigned stackSize,   /* stack size in bytes */
 	_ContextEntry pEntry, /* entry point */
@@ -146,6 +146,4 @@ void *_NewContext(
 	/* initial values in all other registers/CCS entries are irrelevant */
 
 	CONTEXT_MONITOR_INIT(pCcs);
-
-	return pCcs;
 }

arch/arm/include/nanok.h

@@ -199,7 +199,7 @@ static ALWAYS_INLINE void fiberRtnValueSet(
 }
 
 extern void _insert_ccs(tCCS **, tCCS *);
-extern void *_NewContext(char *,
+extern void _NewContext(char *,
 			 unsigned,
 			 _ContextEntry,
 			 _ContextArg,

arch/x86/core/nanocontext.c

@@ -75,7 +75,6 @@ void _ContextEntryWrapper(_ContextEntry, _ContextArg, _ContextArg, _ContextArg);
 */
 
 static void _NewContextInternal(
-	tCCS *ccs,	  /* pointer to the new task's ccs */
 	char *pStackMem,    /* pointer to context stack memory */
 	unsigned stackSize, /* size of stack in bytes */
 	int priority,       /* context priority */
@@ -83,6 +82,7 @@ static void _NewContextInternal(
 	)
 {
 	unsigned long *pInitialCtx;
+	tCCS *ccs = (tCCS *) pStackMem;    /* pointer to the new task's ccs */
 
 #ifndef CONFIG_FP_SHARING
 	ARG_UNUSED(options);
@@ -288,7 +288,7 @@ __asm__("\t.globl _context_entry\n"
 * \NOMANUAL
 */
 
-void *_NewContext(
+void _NewContext(
 	char *pStackMem,      /* pointer to aligned stack memory */
 	unsigned stackSize,   /* size of stack in bytes */
 	_ContextEntry pEntry, /* context entry point function */
@@ -299,7 +299,6 @@ void *_NewContext(
 	unsigned options  /* context options: USE_FP, USE_SSE */
 	)
 {
-	tCCS *ccs;
 	unsigned long *pInitialContext;
 
 	/* carve the context entry struct from the "base" of the stack */
@@ -354,10 +353,5 @@ void *_NewContext(
 	 * stack
 	 */
 
-	ccs = (tCCS *) pStackMem;
-
-	_NewContextInternal(ccs, pStackMem, stackSize, priority, options);
-
-
-	return ((void *)ccs);
+	_NewContextInternal(pStackMem, stackSize, priority, options);
 }

arch/x86/include/nanok.h

@@ -865,7 +865,7 @@ extern void nano_cpu_atomic_idle(unsigned int imask);
 extern unsigned _Swap(unsigned int mask);
 extern void _insert_ccs(tCCS **queue, tCCS *ccs);
 
-extern void *_NewContext(char *pStack,
+extern void _NewContext(char *pStack,
 			 unsigned stackSize,
 			 _ContextEntry pEntry,
 			 _ContextArg arg1,

kernel/microkernel/k_task.c

@@ -205,7 +205,6 @@ void start_task(struct k_proc *X,	 /* ptr to task control block */
 			      )
 {
 	unsigned int contextOptions;
-	void *pNewContext;
 
 /* Note: the field X->worksize now represents the task size in bytes */
 
@@ -225,7 +224,7 @@ void start_task(struct k_proc *X,	 /* ptr to task control block */
 	 * the context is a task, rather than a fiber.
 	 */
 
-	pNewContext = (tCCS *)_NewContext((char *)X->workspace, /* pStackMem */
+	_NewContext((char *)X->workspace, /* pStackMem */
 				X->worksize,		/* stackSize */
 				(_ContextEntry)func,  /* pEntry */
 				(void *)0,		/* parameter1 */
@@ -235,7 +234,6 @@ void start_task(struct k_proc *X,	 /* ptr to task control block */
 				contextOptions	/* options */
 				);
 
-	X->workspace = (char *)pNewContext;
 	X->fabort = NULL;
 
 	reset_state_bit(X, TF_STOP | TF_TERM);

kernel/nanokernel/nano_fiber.c

@@ -83,7 +83,8 @@ void _fiber_start(char *pStack,
 	memset((char *)pStack, 0xaa, stackSize);
 #endif
 
-	ccs = _NewContext((char *)pStack,
+	ccs = (tCCS *) pStack;
+	_NewContext(pStack,
 			  stackSize,
 			  (_ContextEntry)pEntry,
 			  (void *)parameter1,

kernel/nanokernel/nano_init.c

@@ -152,7 +152,8 @@ static void nano_init(tCCS *dummyOutContext)
 	 * (or idle task). The entry point for this context is 'main'.
 	 */
 
-	_nanokernel.task =
+	_nanokernel.task = (tCCS *) main_task_stack;
+
 	_NewContext(main_task_stack,	/* pStackMem */
 			    CONFIG_MAIN_STACK_SIZE, /* stackSize */
 			    (_ContextEntry)main,	 /* pEntry */