Updates to CM4_MPU RCDS port

- System calls are now only allowed from kernel code. This change can be turned on
  or off using configENFORCE_SYSTEM_CALLS_FROM_KERNEL_ONLY.
- MPU is disabled before reprogramming it and enabled afterwards to be compliant
  with ARM recommendations.
pull/8/head
Gaurav Aggarwal 5 years ago
parent 18c3e5e02a
commit cef6548e8b

@ -30,8 +30,8 @@
*----------------------------------------------------------*/ *----------------------------------------------------------*/
/* Defining MPU_WRAPPERS_INCLUDED_FROM_API_FILE prevents task.h from redefining /* Defining MPU_WRAPPERS_INCLUDED_FROM_API_FILE prevents task.h from redefining
all the API functions to use the MPU wrappers. That should only be done when * all the API functions to use the MPU wrappers. That should only be done when
task.h is included from an application file. */ * task.h is included from an application file. */
#define MPU_WRAPPERS_INCLUDED_FROM_API_FILE #define MPU_WRAPPERS_INCLUDED_FROM_API_FILE
/* Scheduler includes. */ /* Scheduler includes. */
@ -99,12 +99,12 @@ task.h is included from an application file. */
#define portOFFSET_TO_PC ( 6 ) #define portOFFSET_TO_PC ( 6 )
/* For strict compliance with the Cortex-M spec the task start address should /* For strict compliance with the Cortex-M spec the task start address should
have bit-0 clear, as it is loaded into the PC on exit from an ISR. */ * have bit-0 clear, as it is loaded into the PC on exit from an ISR. */
#define portSTART_ADDRESS_MASK ( ( StackType_t ) 0xfffffffeUL ) #define portSTART_ADDRESS_MASK ( ( StackType_t ) 0xfffffffeUL )
/* Each task maintains its own interrupt status in the critical nesting /* Each task maintains its own interrupt status in the critical nesting
variable. Note this is not saved as part of the task context as context * variable. Note this is not saved as part of the task context as context
switches can only occur when uxCriticalNesting is zero. */ * switches can only occur when uxCriticalNesting is zero. */
static UBaseType_t uxCriticalNesting = 0xaaaaaaaa; static UBaseType_t uxCriticalNesting = 0xaaaaaaaa;
/* /*
@ -205,7 +205,7 @@ extern void vPortResetPrivilege( BaseType_t xRunningPrivileged );
StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters, BaseType_t xRunPrivileged ) StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters, BaseType_t xRunPrivileged )
{ {
/* Simulate the stack frame as it would be created by a context switch /* Simulate the stack frame as it would be created by a context switch
interrupt. */ * interrupt. */
pxTopOfStack--; /* Offset added to account for the way the MCU uses the stack on entry/exit of interrupts. */ pxTopOfStack--; /* Offset added to account for the way the MCU uses the stack on entry/exit of interrupts. */
*pxTopOfStack = portINITIAL_XPSR; /* xPSR */ *pxTopOfStack = portINITIAL_XPSR; /* xPSR */
pxTopOfStack--; pxTopOfStack--;
@ -216,7 +216,7 @@ StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t px
*pxTopOfStack = ( StackType_t ) pvParameters; /* R0 */ *pxTopOfStack = ( StackType_t ) pvParameters; /* R0 */
/* A save method is being used that requires each task to maintain its /* A save method is being used that requires each task to maintain its
own exec return value. */ * own exec return value. */
pxTopOfStack--; pxTopOfStack--;
*pxTopOfStack = portINITIAL_EXC_RETURN; *pxTopOfStack = portINITIAL_EXC_RETURN;
@ -238,11 +238,16 @@ StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t px
void prvSVCHandler( uint32_t *pulParam ) void prvSVCHandler( uint32_t *pulParam )
{ {
uint8_t ucSVCNumber; uint8_t ucSVCNumber;
uint32_t ulReg; uint32_t ulReg, ulPC;
#if( configENFORCE_SYSTEM_CALLS_FROM_KERNEL_ONLY == 1 )
/* The stack contains: r0, r1, r2, r3, r12, r14, the return address and extern uint32_t __syscalls_flash_start__;
xPSR. The first argument (r0) is pulParam[ 0 ]. */ extern uint32_t __syscalls_flash_end__;
ucSVCNumber = ( ( uint8_t * ) pulParam[ portOFFSET_TO_PC ] )[ -2 ]; #endif /* #if( configENFORCE_SYSTEM_CALLS_FROM_KERNEL_ONLY == 1 ) */
/* The stack contains: r0, r1, r2, r3, r12, LR, PC and xPSR. The first
* argument (r0) is pulParam[ 0 ]. */
ulPC = pulParam[ portOFFSET_TO_PC ];
ucSVCNumber = ( ( uint8_t * ) ulPC )[ -2 ];
switch( ucSVCNumber ) switch( ucSVCNumber )
{ {
case portSVC_START_SCHEDULER : portNVIC_SYSPRI1_REG |= portNVIC_SVC_PRI; case portSVC_START_SCHEDULER : portNVIC_SYSPRI1_REG |= portNVIC_SVC_PRI;
@ -251,14 +256,30 @@ uint32_t ulReg;
case portSVC_YIELD : portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT; case portSVC_YIELD : portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT;
/* Barriers are normally not required /* Barriers are normally not required
but do ensure the code is completely * but do ensure the code is completely
within the specified behaviour for the * within the specified behaviour for the
architecture. */ * architecture. */
__asm volatile( "dsb" ); __asm volatile( "dsb" );
__asm volatile( "isb" ); __asm volatile( "isb" );
break; break;
#if( configENFORCE_SYSTEM_CALLS_FROM_KERNEL_ONLY == 1 )
case portSVC_RAISE_PRIVILEGE : /* Only raise the privilege, if the
* svc was raised from any of the
* system calls. */
if( ulPC >= ( uint32_t ) __syscalls_flash_start__ &&
ulPC <= ( uint32_t ) __syscalls_flash_end__ )
{
__asm
{
mrs ulReg, control /* Obtain current control value. */
bic ulReg, #1 /* Set privilege bit. */
msr control, ulReg /* Write back new control value. */
}
}
break;
#else
case portSVC_RAISE_PRIVILEGE : __asm case portSVC_RAISE_PRIVILEGE : __asm
{ {
mrs ulReg, control /* Obtain current control value. */ mrs ulReg, control /* Obtain current control value. */
@ -266,6 +287,7 @@ uint32_t ulReg;
msr control, ulReg /* Write back new control value. */ msr control, ulReg /* Write back new control value. */
} }
break; break;
#endif /* #if( configENFORCE_SYSTEM_CALLS_FROM_KERNEL_ONLY == 1 ) */
default : /* Unknown SVC call. */ default : /* Unknown SVC call. */
break; break;
@ -304,9 +326,23 @@ __asm void prvRestoreContextOfFirstTask( void )
ldr r1, [r3] ldr r1, [r3]
ldr r0, [r1] /* The first item in the TCB is the task top of stack. */ ldr r0, [r1] /* The first item in the TCB is the task top of stack. */
add r1, r1, #4 /* Move onto the second item in the TCB... */ add r1, r1, #4 /* Move onto the second item in the TCB... */
dmb /* Complete outstanding transfers before disabling MPU. */
ldr r2, =0xe000ed94 /* MPU_CTRL register. */
ldr r3, [r2] /* Read the value of MPU_CTRL. */
bic r3, r3, #1 /* r3 = r3 & ~1 i.e. Clear the bit 0 in r3. */
str r3, [r2] /* Disable MPU. */
ldr r2, =0xe000ed9c /* Region Base Address register. */ ldr r2, =0xe000ed9c /* Region Base Address register. */
ldmia r1!, {r4-r11} /* Read 4 sets of MPU registers. */ ldmia r1!, {r4-r11} /* Read 4 sets of MPU registers. */
stmia r2!, {r4-r11} /* Write 4 sets of MPU registers. */ stmia r2!, {r4-r11} /* Write 4 sets of MPU registers. */
ldr r2, =0xe000ed94 /* MPU_CTRL register. */
ldr r3, [r2] /* Read the value of MPU_CTRL. */
orr r3, r3, #1 /* r3 = r3 | 1 i.e. Set the bit 0 in r3. */
str r3, [r2] /* Enable MPU. */
dsb /* Force memory writes before continuing. */
ldmia r0!, {r3-r11, r14} /* Pop the registers that are not automatically saved on exception entry. */ ldmia r0!, {r3-r11, r14} /* Pop the registers that are not automatically saved on exception entry. */
msr control, r3 msr control, r3
msr psp, r0 /* Restore the task stack pointer. */ msr psp, r0 /* Restore the task stack pointer. */
@ -323,7 +359,7 @@ __asm void prvRestoreContextOfFirstTask( void )
BaseType_t xPortStartScheduler( void ) BaseType_t xPortStartScheduler( void )
{ {
/* configMAX_SYSCALL_INTERRUPT_PRIORITY must not be set to 0. See /* configMAX_SYSCALL_INTERRUPT_PRIORITY must not be set to 0. See
http://www.FreeRTOS.org/RTOS-Cortex-M3-M4.html */ * http://www.FreeRTOS.org/RTOS-Cortex-M3-M4.html */
configASSERT( ( configMAX_SYSCALL_INTERRUPT_PRIORITY ) ); configASSERT( ( configMAX_SYSCALL_INTERRUPT_PRIORITY ) );
#if( configASSERT_DEFINED == 1 ) #if( configASSERT_DEFINED == 1 )
@ -333,15 +369,15 @@ BaseType_t xPortStartScheduler( void )
volatile uint8_t ucMaxPriorityValue; volatile uint8_t ucMaxPriorityValue;
/* Determine the maximum priority from which ISR safe FreeRTOS API /* Determine the maximum priority from which ISR safe FreeRTOS API
functions can be called. ISR safe functions are those that end in * functions can be called. ISR safe functions are those that end in
"FromISR". FreeRTOS maintains separate thread and ISR API functions to * "FromISR". FreeRTOS maintains separate thread and ISR API functions to
ensure interrupt entry is as fast and simple as possible. * ensure interrupt entry is as fast and simple as possible.
Save the interrupt priority value that is about to be clobbered. */ * Save the interrupt priority value that is about to be clobbered. */
ulOriginalPriority = *pucFirstUserPriorityRegister; ulOriginalPriority = *pucFirstUserPriorityRegister;
/* Determine the number of priority bits available. First write to all /* Determine the number of priority bits available. First write to all
possible bits. */ * possible bits. */
*pucFirstUserPriorityRegister = portMAX_8_BIT_VALUE; *pucFirstUserPriorityRegister = portMAX_8_BIT_VALUE;
/* Read the value back to see how many bits stuck. */ /* Read the value back to see how many bits stuck. */
@ -351,7 +387,7 @@ BaseType_t xPortStartScheduler( void )
ucMaxSysCallPriority = configMAX_SYSCALL_INTERRUPT_PRIORITY & ucMaxPriorityValue; ucMaxSysCallPriority = configMAX_SYSCALL_INTERRUPT_PRIORITY & ucMaxPriorityValue;
/* Calculate the maximum acceptable priority group value for the number /* Calculate the maximum acceptable priority group value for the number
of bits read back. */ * of bits read back. */
ulMaxPRIGROUPValue = portMAX_PRIGROUP_BITS; ulMaxPRIGROUPValue = portMAX_PRIGROUP_BITS;
while( ( ucMaxPriorityValue & portTOP_BIT_OF_BYTE ) == portTOP_BIT_OF_BYTE ) while( ( ucMaxPriorityValue & portTOP_BIT_OF_BYTE ) == portTOP_BIT_OF_BYTE )
{ {
@ -362,8 +398,8 @@ BaseType_t xPortStartScheduler( void )
#ifdef __NVIC_PRIO_BITS #ifdef __NVIC_PRIO_BITS
{ {
/* Check the CMSIS configuration that defines the number of /* Check the CMSIS configuration that defines the number of
priority bits matches the number of priority bits actually queried * priority bits matches the number of priority bits actually queried
from the hardware. */ * from the hardware. */
configASSERT( ( portMAX_PRIGROUP_BITS - ulMaxPRIGROUPValue ) == __NVIC_PRIO_BITS ); configASSERT( ( portMAX_PRIGROUP_BITS - ulMaxPRIGROUPValue ) == __NVIC_PRIO_BITS );
} }
#endif #endif
@ -371,26 +407,26 @@ BaseType_t xPortStartScheduler( void )
#ifdef configPRIO_BITS #ifdef configPRIO_BITS
{ {
/* Check the FreeRTOS configuration that defines the number of /* Check the FreeRTOS configuration that defines the number of
priority bits matches the number of priority bits actually queried * priority bits matches the number of priority bits actually queried
from the hardware. */ * from the hardware. */
configASSERT( ( portMAX_PRIGROUP_BITS - ulMaxPRIGROUPValue ) == configPRIO_BITS ); configASSERT( ( portMAX_PRIGROUP_BITS - ulMaxPRIGROUPValue ) == configPRIO_BITS );
} }
#endif #endif
/* Shift the priority group value back to its position within the AIRCR /* Shift the priority group value back to its position within the AIRCR
register. */ * register. */
ulMaxPRIGROUPValue <<= portPRIGROUP_SHIFT; ulMaxPRIGROUPValue <<= portPRIGROUP_SHIFT;
ulMaxPRIGROUPValue &= portPRIORITY_GROUP_MASK; ulMaxPRIGROUPValue &= portPRIORITY_GROUP_MASK;
/* Restore the clobbered interrupt priority register to its original /* Restore the clobbered interrupt priority register to its original
value. */ * value. */
*pucFirstUserPriorityRegister = ulOriginalPriority; *pucFirstUserPriorityRegister = ulOriginalPriority;
} }
#endif /* conifgASSERT_DEFINED */ #endif /* conifgASSERT_DEFINED */
/* Make PendSV and SysTick the same priority as the kernel, and the SVC /* Make PendSV and SysTick the same priority as the kernel, and the SVC
handler higher priority so it can be used to exit a critical section (where * handler higher priority so it can be used to exit a critical section (where
lower priorities are masked). */ * lower priorities are masked). */
portNVIC_SYSPRI2_REG |= portNVIC_PENDSV_PRI; portNVIC_SYSPRI2_REG |= portNVIC_PENDSV_PRI;
portNVIC_SYSPRI2_REG |= portNVIC_SYSTICK_PRI; portNVIC_SYSPRI2_REG |= portNVIC_SYSTICK_PRI;
@ -398,7 +434,7 @@ BaseType_t xPortStartScheduler( void )
prvSetupMPU(); prvSetupMPU();
/* Start the timer that generates the tick ISR. Interrupts are disabled /* Start the timer that generates the tick ISR. Interrupts are disabled
here already. */ * here already. */
prvSetupTimerInterrupt(); prvSetupTimerInterrupt();
/* Initialise the critical nesting count ready for the first task. */ /* Initialise the critical nesting count ready for the first task. */
@ -429,9 +465,9 @@ __asm void prvStartFirstTask( void )
/* Set the msp back to the start of the stack. */ /* Set the msp back to the start of the stack. */
msr msp, r0 msr msp, r0
/* Clear the bit that indicates the FPU is in use in case the FPU was used /* Clear the bit that indicates the FPU is in use in case the FPU was used
before the scheduler was started - which would otherwise result in the * before the scheduler was started - which would otherwise result in the
unnecessary leaving of space in the SVC stack for lazy saving of FPU * unnecessary leaving of space in the SVC stack for lazy saving of FPU
registers. */ * registers. */
mov r0, #0 mov r0, #0
msr control, r0 msr control, r0
/* Globally enable interrupts. */ /* Globally enable interrupts. */
@ -447,7 +483,7 @@ __asm void prvStartFirstTask( void )
void vPortEndScheduler( void ) void vPortEndScheduler( void )
{ {
/* Not implemented in ports where there is nothing to return to. /* Not implemented in ports where there is nothing to return to.
Artificially force an assert. */ * Artificially force an assert. */
configASSERT( uxCriticalNesting == 1000UL ); configASSERT( uxCriticalNesting == 1000UL );
} }
/*-----------------------------------------------------------*/ /*-----------------------------------------------------------*/
@ -511,9 +547,23 @@ __asm void xPortPendSVHandler( void )
ldr r1, [r3] ldr r1, [r3]
ldr r0, [r1] /* The first item in the TCB is the task top of stack. */ ldr r0, [r1] /* The first item in the TCB is the task top of stack. */
add r1, r1, #4 /* Move onto the second item in the TCB... */ add r1, r1, #4 /* Move onto the second item in the TCB... */
dmb /* Complete outstanding transfers before disabling MPU. */
ldr r2, =0xe000ed94 /* MPU_CTRL register. */
ldr r3, [r2] /* Read the value of MPU_CTRL. */
bic r3, r3, #1 /* r3 = r3 & ~1 i.e. Clear the bit 0 in r3. */
str r3, [r2] /* Disable MPU. */
ldr r2, =0xe000ed9c /* Region Base Address register. */ ldr r2, =0xe000ed9c /* Region Base Address register. */
ldmia r1!, {r4-r11} /* Read 4 sets of MPU registers. */ ldmia r1!, {r4-r11} /* Read 4 sets of MPU registers. */
stmia r2!, {r4-r11} /* Write 4 sets of MPU registers. */ stmia r2!, {r4-r11} /* Write 4 sets of MPU registers. */
ldr r2, =0xe000ed94 /* MPU_CTRL register. */
ldr r3, [r2] /* Read the value of MPU_CTRL. */
orr r3, r3, #1 /* r3 = r3 | 1 i.e. Set the bit 0 in r3. */
str r3, [r2] /* Enable MPU. */
dsb /* Force memory writes before continuing. */
ldmia r0!, {r3-r11, r14} /* Pop the registers that are not automatically saved on exception entry. */ ldmia r0!, {r3-r11, r14} /* Pop the registers that are not automatically saved on exception entry. */
msr control, r3 msr control, r3
@ -608,8 +658,8 @@ extern uint32_t __privileged_data_end__;
( portMPU_REGION_ENABLE ); ( portMPU_REGION_ENABLE );
/* Setup the first 16K for privileged only access (even though less /* Setup the first 16K for privileged only access (even though less
than 10K is actually being used). This is where the kernel code is * than 10K is actually being used). This is where the kernel code is
placed. */ * placed. */
portMPU_REGION_BASE_ADDRESS_REG = ( ( uint32_t ) __FLASH_segment_start__ ) | /* Base address. */ portMPU_REGION_BASE_ADDRESS_REG = ( ( uint32_t ) __FLASH_segment_start__ ) | /* Base address. */
( portMPU_REGION_VALID ) | ( portMPU_REGION_VALID ) |
( portPRIVILEGED_FLASH_REGION ); ( portPRIVILEGED_FLASH_REGION );
@ -620,7 +670,7 @@ extern uint32_t __privileged_data_end__;
( portMPU_REGION_ENABLE ); ( portMPU_REGION_ENABLE );
/* Setup the privileged data RAM region. This is where the kernel data /* Setup the privileged data RAM region. This is where the kernel data
is placed. */ * is placed. */
portMPU_REGION_BASE_ADDRESS_REG = ( ( uint32_t ) __privileged_data_start__ ) | /* Base address. */ portMPU_REGION_BASE_ADDRESS_REG = ( ( uint32_t ) __privileged_data_start__ ) | /* Base address. */
( portMPU_REGION_VALID ) | ( portMPU_REGION_VALID ) |
( portPRIVILEGED_RAM_REGION ); ( portPRIVILEGED_RAM_REGION );
@ -631,7 +681,7 @@ extern uint32_t __privileged_data_end__;
( portMPU_REGION_ENABLE ); ( portMPU_REGION_ENABLE );
/* By default allow everything to access the general peripherals. The /* By default allow everything to access the general peripherals. The
system peripherals and registers are protected. */ * system peripherals and registers are protected. */
portMPU_REGION_BASE_ADDRESS_REG = ( portPERIPHERALS_START_ADDRESS ) | portMPU_REGION_BASE_ADDRESS_REG = ( portPERIPHERALS_START_ADDRESS ) |
( portMPU_REGION_VALID ) | ( portMPU_REGION_VALID ) |
( portGENERAL_PERIPHERALS_REGION ); ( portGENERAL_PERIPHERALS_REGION );
@ -654,7 +704,7 @@ static uint32_t prvGetMPURegionSizeSetting( uint32_t ulActualSizeInBytes )
uint32_t ulRegionSize, ulReturnValue = 4; uint32_t ulRegionSize, ulReturnValue = 4;
/* 32 is the smallest region size, 31 is the largest valid value for /* 32 is the smallest region size, 31 is the largest valid value for
ulReturnValue. */ * ulReturnValue. */
for( ulRegionSize = 32UL; ulReturnValue < 31UL; ( ulRegionSize <<= 1UL ) ) for( ulRegionSize = 32UL; ulReturnValue < 31UL; ( ulRegionSize <<= 1UL ) )
{ {
if( ulActualSizeInBytes <= ulRegionSize ) if( ulActualSizeInBytes <= ulRegionSize )
@ -668,7 +718,7 @@ uint32_t ulRegionSize, ulReturnValue = 4;
} }
/* Shift the code by one before returning so it can be written directly /* Shift the code by one before returning so it can be written directly
into the the correct bit position of the attribute register. */ * into the the correct bit position of the attribute register. */
return ( ulReturnValue << 1UL ); return ( ulReturnValue << 1UL );
} }
/*-----------------------------------------------------------*/ /*-----------------------------------------------------------*/
@ -723,7 +773,7 @@ uint32_t ul;
( portMPU_REGION_ENABLE ); ( portMPU_REGION_ENABLE );
/* Re-instate the privileged only RAM region as xRegion[ 0 ] will have /* Re-instate the privileged only RAM region as xRegion[ 0 ] will have
just removed the privileged only parameters. */ * just removed the privileged only parameters. */
xMPUSettings->xRegion[ 1 ].ulRegionBaseAddress = xMPUSettings->xRegion[ 1 ].ulRegionBaseAddress =
( ( uint32_t ) __privileged_data_start__ ) | /* Base address. */ ( ( uint32_t ) __privileged_data_start__ ) | /* Base address. */
( portMPU_REGION_VALID ) | ( portMPU_REGION_VALID ) |
@ -745,9 +795,9 @@ uint32_t ul;
else else
{ {
/* This function is called automatically when the task is created - in /* This function is called automatically when the task is created - in
which case the stack region parameters will be valid. At all other * which case the stack region parameters will be valid. At all other
times the stack parameters will not be valid and it is assumed that the * times the stack parameters will not be valid and it is assumed that the
stack region has already been configured. */ * stack region has already been configured. */
if( ulStackDepth > 0 ) if( ulStackDepth > 0 )
{ {
/* Define the region that allows access to the stack. */ /* Define the region that allows access to the stack. */
@ -770,8 +820,8 @@ uint32_t ul;
if( ( xRegions[ lIndex ] ).ulLengthInBytes > 0UL ) if( ( xRegions[ lIndex ] ).ulLengthInBytes > 0UL )
{ {
/* Translate the generic region definition contained in /* Translate the generic region definition contained in
xRegions into the CM3 specific MPU settings that are then * xRegions into the CM3 specific MPU settings that are then
stored in xMPUSettings. */ * stored in xMPUSettings. */
xMPUSettings->xRegion[ ul ].ulRegionBaseAddress = xMPUSettings->xRegion[ ul ].ulRegionBaseAddress =
( ( uint32_t ) xRegions[ lIndex ].pvBaseAddress ) | ( ( uint32_t ) xRegions[ lIndex ].pvBaseAddress ) |
( portMPU_REGION_VALID ) | ( portMPU_REGION_VALID ) |
@ -821,47 +871,46 @@ __asm uint32_t prvPortGetIPSR( void )
ucCurrentPriority = pcInterruptPriorityRegisters[ ulCurrentInterrupt ]; ucCurrentPriority = pcInterruptPriorityRegisters[ ulCurrentInterrupt ];
/* The following assertion will fail if a service routine (ISR) for /* The following assertion will fail if a service routine (ISR) for
an interrupt that has been assigned a priority above * an interrupt that has been assigned a priority above
configMAX_SYSCALL_INTERRUPT_PRIORITY calls an ISR safe FreeRTOS API * configMAX_SYSCALL_INTERRUPT_PRIORITY calls an ISR safe FreeRTOS API
function. ISR safe FreeRTOS API functions must *only* be called * function. ISR safe FreeRTOS API functions must *only* be called
from interrupts that have been assigned a priority at or below * from interrupts that have been assigned a priority at or below
configMAX_SYSCALL_INTERRUPT_PRIORITY. * configMAX_SYSCALL_INTERRUPT_PRIORITY.
Numerically low interrupt priority numbers represent logically high * Numerically low interrupt priority numbers represent logically high
interrupt priorities, therefore the priority of the interrupt must * interrupt priorities, therefore the priority of the interrupt must
be set to a value equal to or numerically *higher* than * be set to a value equal to or numerically *higher* than
configMAX_SYSCALL_INTERRUPT_PRIORITY. * configMAX_SYSCALL_INTERRUPT_PRIORITY.
Interrupts that use the FreeRTOS API must not be left at their * Interrupts that use the FreeRTOS API must not be left at their
default priority of zero as that is the highest possible priority, * default priority of zero as that is the highest possible priority,
which is guaranteed to be above configMAX_SYSCALL_INTERRUPT_PRIORITY, * which is guaranteed to be above configMAX_SYSCALL_INTERRUPT_PRIORITY,
and therefore also guaranteed to be invalid. * and therefore also guaranteed to be invalid.
FreeRTOS maintains separate thread and ISR API functions to ensure * FreeRTOS maintains separate thread and ISR API functions to ensure
interrupt entry is as fast and simple as possible. * interrupt entry is as fast and simple as possible.
The following links provide detailed information: * The following links provide detailed information:
http://www.freertos.org/RTOS-Cortex-M3-M4.html * http://www.freertos.org/RTOS-Cortex-M3-M4.html
http://www.freertos.org/FAQHelp.html */ * http://www.freertos.org/FAQHelp.html */
configASSERT( ucCurrentPriority >= ucMaxSysCallPriority ); configASSERT( ucCurrentPriority >= ucMaxSysCallPriority );
} }
/* Priority grouping: The interrupt controller (NVIC) allows the bits /* Priority grouping: The interrupt controller (NVIC) allows the bits
that define each interrupt's priority to be split between bits that * that define each interrupt's priority to be split between bits that
define the interrupt's pre-emption priority bits and bits that define * define the interrupt's pre-emption priority bits and bits that define
the interrupt's sub-priority. For simplicity all bits must be defined * the interrupt's sub-priority. For simplicity all bits must be defined
to be pre-emption priority bits. The following assertion will fail if * to be pre-emption priority bits. The following assertion will fail if
this is not the case (if some bits represent a sub-priority). * this is not the case (if some bits represent a sub-priority).
If the application only uses CMSIS libraries for interrupt * If the application only uses CMSIS libraries for interrupt
configuration then the correct setting can be achieved on all Cortex-M * configuration then the correct setting can be achieved on all Cortex-M
devices by calling NVIC_SetPriorityGrouping( 0 ); before starting the * devices by calling NVIC_SetPriorityGrouping( 0 ); before starting the
scheduler. Note however that some vendor specific peripheral libraries * scheduler. Note however that some vendor specific peripheral libraries
assume a non-zero priority group setting, in which cases using a value * assume a non-zero priority group setting, in which cases using a value
of zero will result in unpredicable behaviour. */ * of zero will result in unpredicable behaviour. */
configASSERT( ( portAIRCR_REG & portPRIORITY_GROUP_MASK ) <= ulMaxPRIGROUPValue ); configASSERT( ( portAIRCR_REG & portPRIORITY_GROUP_MASK ) <= ulMaxPRIGROUPValue );
} }
#endif /* configASSERT_DEFINED */ #endif /* configASSERT_DEFINED */
/*-----------------------------------------------------------*/

@ -77,6 +77,7 @@ typedef unsigned long UBaseType_t;
#define portMPU_REGION_PRIVILEGED_READ_ONLY ( 0x05UL << 24UL ) #define portMPU_REGION_PRIVILEGED_READ_ONLY ( 0x05UL << 24UL )
#define portMPU_REGION_READ_ONLY ( 0x06UL << 24UL ) #define portMPU_REGION_READ_ONLY ( 0x06UL << 24UL )
#define portMPU_REGION_PRIVILEGED_READ_WRITE ( 0x01UL << 24UL ) #define portMPU_REGION_PRIVILEGED_READ_WRITE ( 0x01UL << 24UL )
#define portMPU_REGION_PRIVILEGED_READ_WRITE_UNPRIV_READ_ONLY ( 0x02UL << 24UL )
#define portMPU_REGION_CACHEABLE_BUFFERABLE ( 0x07UL << 16UL ) #define portMPU_REGION_CACHEABLE_BUFFERABLE ( 0x07UL << 16UL )
#define portMPU_REGION_EXECUTE_NEVER ( 0x01UL << 28UL ) #define portMPU_REGION_EXECUTE_NEVER ( 0x01UL << 28UL )
@ -301,6 +302,12 @@ BaseType_t xReturn;
} }
/*-----------------------------------------------------------*/ /*-----------------------------------------------------------*/
#ifndef configENFORCE_SYSTEM_CALLS_FROM_KERNEL_ONLY
#warning "configENFORCE_SYSTEM_CALLS_FROM_KERNEL_ONLY is not defined. We recommend defining it to 1 in FreeRTOSConfig.h for better security."
#define configENFORCE_SYSTEM_CALLS_FROM_KERNEL_ONLY 0
#endif
/*-----------------------------------------------------------*/
#ifdef __cplusplus #ifdef __cplusplus
} }
#endif #endif

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