I like the simplification. We should also clean up any BSPs that have
dead code beyond calling boot_card().
Does it make sense to add noreturn attributes to the initialization
call path starting with boot_card through
rtems_initialize_start_multitasking()?
-Gedare
On Thu, Feb 13, 2014 at 4:09 AM, Sebastian Huber
<sebastian.hu...@embedded-brains.de> wrote:
> Do not return to BSP context in the exit() shutdown path. This makes it
> possible to re-use the initialization stack. It can be used for the
> interrupt stack for example. On targets with a small RAM this is a
> considerable benefit.
>
> This change eliminates also some special cases and simplifies the code.
>
> Disable thread dispatching in rtems_shutdown_executive().
>
> Delete _Thread_Set_global_exit_status(),
> _Thread_Get_global_exit_status() and _Thread_Stop_multitasking().
> ---
> cpukit/sapi/src/exinit.c | 10 +---
> cpukit/sapi/src/exshutdown.c | 18 +++---
> .../score/cpu/arm/armv7m-multitasking-start-stop.c | 36 ++---------
> cpukit/score/cpu/arm/rtems/score/cpu.h | 5 +-
> cpukit/score/include/rtems/score/threadimpl.h | 65
> +-------------------
> cpukit/score/src/smp.c | 2 +-
> cpukit/score/src/threadstartmultitasking.c | 27 +++------
> testsuites/sptests/spsize/size.c | 3 +-
> 8 files changed, 29 insertions(+), 137 deletions(-)
>
> diff --git a/cpukit/sapi/src/exinit.c b/cpukit/sapi/src/exinit.c
> index 10c1559..e8b009b 100644
> --- a/cpukit/sapi/src/exinit.c
> +++ b/cpukit/sapi/src/exinit.c
> @@ -33,7 +33,6 @@
> #include <rtems/config.h>
> #include <rtems/debug.h>
> #include <rtems/extensionimpl.h>
> -#include <rtems/fatal.h>
> #include <rtems/init.h>
> #include <rtems/io.h>
> #include <rtems/score/sysstate.h>
> @@ -215,25 +214,20 @@ void rtems_initialize_device_drivers(void)
>
> void rtems_initialize_start_multitasking(void)
> {
> - uint32_t status;
> -
> _System_state_Set( SYSTEM_STATE_UP );
>
> #if defined(RTEMS_SMP)
> _SMP_Request_other_cores_to_perform_first_context_switch();
> #endif
>
> - _Thread_Start_multitasking( &_Thread_BSP_context );
> + _Thread_Start_multitasking();
>
> /*******************************************************************
> *******************************************************************
> *******************************************************************
> ****** APPLICATION RUNS HERE ******
> - ****** RETURNS WHEN SYSTEM IS SHUT DOWN ******
> + ****** THE FUNCTION NEVER RETURNS ******
> *******************************************************************
> *******************************************************************
> *******************************************************************/
> -
> - status = _Thread_Get_global_exit_status();
> - rtems_fatal( RTEMS_FATAL_SOURCE_EXIT, status );
> }
> diff --git a/cpukit/sapi/src/exshutdown.c b/cpukit/sapi/src/exshutdown.c
> index 7a96869..7cf7d35 100644
> --- a/cpukit/sapi/src/exshutdown.c
> +++ b/cpukit/sapi/src/exshutdown.c
> @@ -38,25 +38,25 @@ void rtems_shutdown_executive(
> uint32_t result
> )
> {
> + _Thread_Disable_dispatch();
> +
> if ( _System_state_Is_up( _System_state_Get() ) ) {
> #if defined(RTEMS_SMP)
> _SMP_Request_other_cores_to_shutdown();
> #endif
>
> - _Thread_Set_global_exit_status( result );
> _System_state_Set( SYSTEM_STATE_SHUTDOWN );
> - _Thread_Stop_multitasking();
> -
> - /*******************************************************************
> - *******************************************************************
> - ****** RETURN TO RTEMS_INITIALIZE_START_MULTITASKING() ******
> - ****** AND THEN TO BOOT_CARD() ******
> - *******************************************************************
> - *******************************************************************/
> + _Internal_error_Occurred( RTEMS_FATAL_SOURCE_EXIT, false, result );
> }
> _Internal_error_Occurred(
> INTERNAL_ERROR_CORE,
> true,
> INTERNAL_ERROR_SHUTDOWN_WHEN_NOT_UP
> );
> +
> + /***************************************************************
> + ***************************************************************
> + * SYSTEM SHUTS DOWN!!! WE DO NOT RETURN TO THIS POINT!!! *
> + ***************************************************************
> + ***************************************************************/
> }
> diff --git a/cpukit/score/cpu/arm/armv7m-multitasking-start-stop.c
> b/cpukit/score/cpu/arm/armv7m-multitasking-start-stop.c
> index f3e96e3..864bb53 100644
> --- a/cpukit/score/cpu/arm/armv7m-multitasking-start-stop.c
> +++ b/cpukit/score/cpu/arm/armv7m-multitasking-start-stop.c
> @@ -1,14 +1,14 @@
> /**
> * @file
> *
> - * @brief ARMV7M Start and Stop Multitasking
> + * @brief ARMV7M Start Multitasking
> */
>
> /*
> - * Copyright (c) 2011 Sebastian Huber. All rights reserved.
> + * Copyright (c) 2011-2014 Sebastian Huber. All rights reserved.
> *
> * embedded brains GmbH
> - * Obere Lagerstr. 30
> + * Dornierstr. 4
> * 82178 Puchheim
> * Germany
> * <rt...@embedded-brains.de>
> @@ -27,18 +27,14 @@
> #ifdef ARM_MULTILIB_ARCH_V7M
>
> void __attribute__((naked)) _ARMV7M_Start_multitasking(
> - Context_Control *bsp,
> Context_Control *heir
> )
> {
> __asm__ volatile (
> - /* Store BSP context */
> - "stm r0, {r4-r11, lr}\n"
> - "str sp, [r0, %[spctxoff]]\n"
> /* Restore heir context */
> - "ldr r2, [r1, %[spctxoff]]\n"
> + "ldr r2, [r0, %[spctxoff]]\n"
> "msr psp, r2\n"
> - "ldm r1, {r4-r11, lr}\n"
> + "ldm r0, {r4-r11, lr}\n"
> /* Enable process stack pointer (PSP) */
> "mrs r2, control\n"
> "orr r2, #0x2\n"
> @@ -50,26 +46,4 @@ void __attribute__((naked)) _ARMV7M_Start_multitasking(
> );
> }
>
> -void __attribute__((naked)) _ARMV7M_Stop_multitasking( Context_Control *bsp )
> -{
> - __asm__ volatile (
> - /* Disable interrupts */
> - "mov r2, #0x80\n"
> - "msr basepri_max, r2\n"
> - /* Restore BSP context */
> - "ldr r2, [r0, %[spctxoff]]\n"
> - "msr msp, r2\n"
> - "ldm r0, {r4-r11, lr}\n"
> - /* Disable process stack pointer (PSP) */
> - "mrs r2, control\n"
> - "bic r2, #0x2\n"
> - "msr control, r2\n"
> - /* Return to BSP */
> - "bx lr\n"
> - :
> - : [spctxoff] "J" (offsetof(Context_Control, register_sp))
> - );
> - __builtin_unreachable();
> -}
> -
> #endif /* ARM_MULTILIB_ARCH_V7M */
> diff --git a/cpukit/score/cpu/arm/rtems/score/cpu.h
> b/cpukit/score/cpu/arm/rtems/score/cpu.h
> index b423dba..f56f9a6 100644
> --- a/cpukit/score/cpu/arm/rtems/score/cpu.h
> +++ b/cpukit/score/cpu/arm/rtems/score/cpu.h
> @@ -458,11 +458,8 @@ void _CPU_Context_restore( Context_Control *new_context )
> RTEMS_COMPILER_NO_RETURN_ATTRIBUTE;
>
> #if defined(ARM_MULTILIB_ARCH_V7M)
> - void _ARMV7M_Start_multitasking( Context_Control *bsp, Context_Control
> *heir );
> - void _ARMV7M_Stop_multitasking( Context_Control *bsp )
> - RTEMS_COMPILER_NO_RETURN_ATTRIBUTE;
> + void _ARMV7M_Start_multitasking( Context_Control *heir );
> #define _CPU_Start_multitasking _ARMV7M_Start_multitasking
> - #define _CPU_Stop_multitasking _ARMV7M_Stop_multitasking
> #endif
>
> void _CPU_Context_volatile_clobber( uintptr_t pattern );
> diff --git a/cpukit/score/include/rtems/score/threadimpl.h
> b/cpukit/score/include/rtems/score/threadimpl.h
> index 4f4fbc7..7c1d2a7 100644
> --- a/cpukit/score/include/rtems/score/threadimpl.h
> +++ b/cpukit/score/include/rtems/score/threadimpl.h
> @@ -20,6 +20,7 @@
> #define _RTEMS_SCORE_THREADIMPL_H
>
> #include <rtems/score/thread.h>
> +#include <rtems/score/interr.h>
> #include <rtems/score/isr.h>
> #include <rtems/score/objectimpl.h>
> #include <rtems/score/statesimpl.h>
> @@ -54,15 +55,6 @@ SCORE_EXTERN void *rtems_ada_self;
> SCORE_EXTERN Objects_Information _Thread_Internal_information;
>
> /**
> - * The following context area contains the context of the "thread"
> - * which invoked the start multitasking routine. This context is
> - * restored as the last action of the stop multitasking routine. Thus
> - * control of the processor can be returned to the environment
> - * which initiated the system.
> - */
> -SCORE_EXTERN Context_Control _Thread_BSP_context;
> -
> -/**
> * The following holds how many user extensions are in the system. This
> * is used to determine how many user extension data areas to allocate
> * per thread.
> @@ -114,13 +106,8 @@ void _Thread_Create_idle(void);
> * This routine initiates multitasking. It is invoked only as
> * part of initialization and its invocation is the last act of
> * the non-multitasking part of the system initialization.
> - *
> - *
> - * - INTERRUPT LATENCY:
> - * + ready chain
> - * + select heir
> */
> -void _Thread_Start_multitasking( Context_Control *context );
> +void _Thread_Start_multitasking( void ) RTEMS_COMPILER_NO_RETURN_ATTRIBUTE;
>
> /**
> * @brief Allocate the requested stack space for the thread.
> @@ -446,36 +433,6 @@ void _Thread_blocking_operation_Cancel(
> );
>
> /**
> - * This routine halts multitasking and returns control to
> - * the "thread" (i.e. the BSP) which initially invoked the
> - * routine which initialized the system.
> - */
> -
> -RTEMS_INLINE_ROUTINE void _Thread_Stop_multitasking( void )
> -{
> -#if defined(_CPU_Stop_multitasking)
> - _CPU_Stop_multitasking( &_Thread_BSP_context );
> -#else
> - /*
> - * This may look a bit of an odd but _Context_Restart_self is just
> - * a very careful restore of a specific context which ensures that
> - * if we were running within the same context, it would work.
> - *
> - * And we will not return to this thread, so there is no point of
> - * saving the context.
> - */
> - _Context_Restart_self( &_Thread_BSP_context );
> -#endif
> -
> - /***************************************************************
> - ***************************************************************
> - * SYSTEM SHUTS DOWN!!! WE DO NOT RETURN TO THIS POINT!!! *
> - ***************************************************************
> - ***************************************************************
> - */
> -}
> -
> -/**
> * This function returns true if the_thread is the currently executing
> * thread, and false otherwise.
> */
> @@ -630,24 +587,6 @@ RTEMS_INLINE_ROUTINE void _Thread_Internal_free (
> _Objects_Free( &_Thread_Internal_information, &the_task->Object );
> }
>
> -RTEMS_INLINE_ROUTINE void _Thread_Set_global_exit_status(
> - uint32_t exit_status
> -)
> -{
> - Thread_Control *idle = (Thread_Control *)
> - _Thread_Internal_information.local_table[ 1 ];
> -
> - idle->Wait.return_code = exit_status;
> -}
> -
> -RTEMS_INLINE_ROUTINE uint32_t _Thread_Get_global_exit_status( void )
> -{
> - const Thread_Control *idle = (const Thread_Control *)
> - _Thread_Internal_information.local_table[ 1 ];
> -
> - return idle->Wait.return_code;
> -}
> -
> RTEMS_INLINE_ROUTINE void _Thread_Signal_notification( Thread_Control
> *thread )
> {
> if ( _ISR_Is_in_progress() && _Thread_Is_executing( thread ) ) {
> diff --git a/cpukit/score/src/smp.c b/cpukit/score/src/smp.c
> index 2f8a488..df1c6d3 100644
> --- a/cpukit/score/src/smp.c
> +++ b/cpukit/score/src/smp.c
> @@ -40,7 +40,7 @@ void rtems_smp_secondary_cpu_initialize( void )
>
> _Per_CPU_Wait_for_state( self_cpu, PER_CPU_STATE_BEGIN_MULTITASKING );
>
> - _Thread_Start_multitasking( NULL );
> + _Thread_Start_multitasking();
> }
>
> void rtems_smp_process_interrupt( void )
> diff --git a/cpukit/score/src/threadstartmultitasking.c
> b/cpukit/score/src/threadstartmultitasking.c
> index 52337ab..a676364 100644
> --- a/cpukit/score/src/threadstartmultitasking.c
> +++ b/cpukit/score/src/threadstartmultitasking.c
> @@ -20,7 +20,7 @@
>
> #include <rtems/score/threadimpl.h>
>
> -void _Thread_Start_multitasking( Context_Control *context )
> +void _Thread_Start_multitasking( void )
> {
> Per_CPU_Control *self_cpu = _Per_CPU_Get();
> Thread_Control *heir = self_cpu->heir;
> @@ -28,7 +28,13 @@ void _Thread_Start_multitasking( Context_Control *context )
> #if defined(RTEMS_SMP)
> _Per_CPU_Change_state( self_cpu, PER_CPU_STATE_UP );
>
> + /*
> + * Threads begin execution in the _Thread_Handler() function. This
> + * function will set the thread dispatch disable level to zero and calls
> + * _Per_CPU_Release().
> + */
> _Per_CPU_Acquire( self_cpu );
> + self_cpu->thread_dispatch_disable_level = 1;
>
> self_cpu->executing->is_executing = false;
> heir->is_executing = true;
> @@ -59,26 +65,9 @@ void _Thread_Start_multitasking( Context_Control *context )
> _Context_Restore_fp( &heir->fp_context );
> #endif
>
> -#if defined(RTEMS_SMP)
> - if ( context != NULL ) {
> -#endif
> -
> #if defined(_CPU_Start_multitasking)
> - _CPU_Start_multitasking( context, &heir->Registers );
> + _CPU_Start_multitasking( &heir->Registers );
> #else
> - _Context_Switch( context, &heir->Registers );
> -#endif
> -
> -#if defined(RTEMS_SMP)
> - } else {
> - /*
> - * Threads begin execution in the _Thread_Handler() function. This
> - * function will set the thread dispatch disable level to zero and calls
> - * _Per_CPU_Release().
> - */
> - self_cpu->thread_dispatch_disable_level = 1;
> -
> _CPU_Context_restore( &heir->Registers );
> - }
> #endif
> }
> diff --git a/testsuites/sptests/spsize/size.c
> b/testsuites/sptests/spsize/size.c
> index f204c05..5b3cefe 100644
> --- a/testsuites/sptests/spsize/size.c
> +++ b/testsuites/sptests/spsize/size.c
> @@ -385,8 +385,7 @@ uninitialized =
>
> /*tasksimpl.h*/ (sizeof _RTEMS_tasks_Information) +
>
> -/*thread.h*/ (sizeof _Thread_BSP_context) +
> - (sizeof _Thread_Dispatch_disable_level) +
> +/*thread.h*/ (sizeof _Thread_Dispatch_disable_level) +
> (sizeof _Thread_Maximum_extensions) +
> (sizeof _Thread_Ticks_per_timeslice) +
> (sizeof _Thread_Executing) +
> --
> 1.7.7
>
> _______________________________________________
> rtems-devel mailing list
> rtems-devel@rtems.org
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