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Updates to CM4_MPU RCDS port

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- 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
parent 18c3e5e02a
commit cef6548e8b
2 changed files with 146 additions and 90 deletions

217
FreeRTOS/Source/portable/RVDS/ARM_CM4_MPU/port.c
Unescape Escape View File

@ -30,8 +30,8 @@
*----------------------------------------------------------*/
/* 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
task.h is included from an application file. */
* all the API functions to use the MPU wrappers. That should only be done when
* task.h is included from an application file. */
#define MPU_WRAPPERS_INCLUDED_FROM_API_FILE
/* Scheduler includes. */
@ -99,12 +99,12 @@ task.h is included from an application file. */
#define portOFFSET_TO_PC ( 6 )
/* 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 )
/* 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
switches can only occur when uxCriticalNesting is zero. */
* variable. Note this is not saved as part of the task context as context
* switches can only occur when uxCriticalNesting is zero. */
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 )
{
/* 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 = portINITIAL_XPSR; /* xPSR */
pxTopOfStack--;
@ -216,7 +216,7 @@ StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t px
*pxTopOfStack = ( StackType_t ) pvParameters; /* R0 */
/* A save method is being used that requires each task to maintain its
own exec return value. */
* own exec return value. */
pxTopOfStack--;
*pxTopOfStack = portINITIAL_EXC_RETURN;
@ -238,11 +238,16 @@ StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t px
void prvSVCHandler( uint32_t *pulParam )
{
uint8_t ucSVCNumber;
uint32_t ulReg;
/* The stack contains: r0, r1, r2, r3, r12, r14, the return address and
xPSR. The first argument (r0) is pulParam[ 0 ]. */
ucSVCNumber = ( ( uint8_t * ) pulParam[ portOFFSET_TO_PC ] )[ -2 ];
uint32_t ulReg, ulPC;
#if( configENFORCE_SYSTEM_CALLS_FROM_KERNEL_ONLY == 1 )
extern uint32_t __syscalls_flash_start__;
extern uint32_t __syscalls_flash_end__;
#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 )
{
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;
/* Barriers are normally not required
but do ensure the code is completely
within the specified behaviour for the
architecture. */
* but do ensure the code is completely
* within the specified behaviour for the
* architecture. */
__asm volatile( "dsb" );
__asm volatile( "isb" );
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
{
mrs ulReg, control /* Obtain current control value. */
@ -266,6 +287,7 @@ uint32_t ulReg;
msr control, ulReg /* Write back new control value. */
}
break;
#endif /* #if( configENFORCE_SYSTEM_CALLS_FROM_KERNEL_ONLY == 1 ) */
default : /* Unknown SVC call. */
break;
@ -304,10 +326,24 @@ __asm void prvRestoreContextOfFirstTask( void )
ldr r1, [r3]
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... */
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. */
ldmia r1!, {r4-r11} /* Read 4 sets of MPU registers. */
stmia r2!, {r4-r11} /* Write 4 sets of MPU registers. */
ldmia r0!, {r3-r11, r14} /* Pop the registers that are not automatically saved on exception entry. */
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. */
msr control, r3
msr psp, r0 /* Restore the task stack pointer. */
mov r0, #0
@ -323,7 +359,7 @@ __asm void prvRestoreContextOfFirstTask( void )
BaseType_t xPortStartScheduler( void )
{
/* 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 ) );
#if( configASSERT_DEFINED == 1 )
@ -333,15 +369,15 @@ BaseType_t xPortStartScheduler( void )
volatile uint8_t ucMaxPriorityValue;
/* Determine the maximum priority from which ISR safe FreeRTOS API
functions can be called. ISR safe functions are those that end in
"FromISR". FreeRTOS maintains separate thread and ISR API functions to
ensure interrupt entry is as fast and simple as possible.
* functions can be called. ISR safe functions are those that end in
* "FromISR". FreeRTOS maintains separate thread and ISR API functions to
* 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;
/* Determine the number of priority bits available. First write to all
possible bits. */
* possible bits. */
*pucFirstUserPriorityRegister = portMAX_8_BIT_VALUE;
/* Read the value back to see how many bits stuck. */
@ -351,7 +387,7 @@ BaseType_t xPortStartScheduler( void )
ucMaxSysCallPriority = configMAX_SYSCALL_INTERRUPT_PRIORITY & ucMaxPriorityValue;
/* Calculate the maximum acceptable priority group value for the number
of bits read back. */
* of bits read back. */
ulMaxPRIGROUPValue = portMAX_PRIGROUP_BITS;
while( ( ucMaxPriorityValue & portTOP_BIT_OF_BYTE ) == portTOP_BIT_OF_BYTE )
{
@ -362,8 +398,8 @@ BaseType_t xPortStartScheduler( void )
#ifdef __NVIC_PRIO_BITS
{
/* Check the CMSIS configuration that defines the number of
priority bits matches the number of priority bits actually queried
from the hardware. */
* priority bits matches the number of priority bits actually queried
* from the hardware. */
configASSERT( ( portMAX_PRIGROUP_BITS - ulMaxPRIGROUPValue ) == __NVIC_PRIO_BITS );
}
#endif
@ -371,26 +407,26 @@ BaseType_t xPortStartScheduler( void )
#ifdef configPRIO_BITS
{
/* Check the FreeRTOS configuration that defines the number of
priority bits matches the number of priority bits actually queried
from the hardware. */
* priority bits matches the number of priority bits actually queried
* from the hardware. */
configASSERT( ( portMAX_PRIGROUP_BITS - ulMaxPRIGROUPValue ) == configPRIO_BITS );
}
#endif
/* Shift the priority group value back to its position within the AIRCR
register. */
* register. */
ulMaxPRIGROUPValue <<= portPRIGROUP_SHIFT;
ulMaxPRIGROUPValue &= portPRIORITY_GROUP_MASK;
/* Restore the clobbered interrupt priority register to its original
value. */
* value. */
*pucFirstUserPriorityRegister = ulOriginalPriority;
}
#endif /* conifgASSERT_DEFINED */
/* 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
lower priorities are masked). */
* handler higher priority so it can be used to exit a critical section (where
* lower priorities are masked). */
portNVIC_SYSPRI2_REG |= portNVIC_PENDSV_PRI;
portNVIC_SYSPRI2_REG |= portNVIC_SYSTICK_PRI;
@ -398,7 +434,7 @@ BaseType_t xPortStartScheduler( void )
prvSetupMPU();
/* Start the timer that generates the tick ISR. Interrupts are disabled
here already. */
* here already. */
prvSetupTimerInterrupt();
/* 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. */
msr msp, r0
/* 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
unnecessary leaving of space in the SVC stack for lazy saving of FPU
registers. */
* before the scheduler was started - which would otherwise result in the
* unnecessary leaving of space in the SVC stack for lazy saving of FPU
* registers. */
mov r0, #0
msr control, r0
/* Globally enable interrupts. */
@ -447,7 +483,7 @@ __asm void prvStartFirstTask( void )
void vPortEndScheduler( void )
{
/* Not implemented in ports where there is nothing to return to.
Artificially force an assert. */
* Artificially force an assert. */
configASSERT( uxCriticalNesting == 1000UL );
}
/*-----------------------------------------------------------*/
@ -511,9 +547,23 @@ __asm void xPortPendSVHandler( void )
ldr r1, [r3]
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... */
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. */
ldmia r1!, {r4-r11} /* Read 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. */
msr control, r3
@ -608,8 +658,8 @@ extern uint32_t __privileged_data_end__;
( portMPU_REGION_ENABLE );
/* Setup the first 16K for privileged only access (even though less
than 10K is actually being used). This is where the kernel code is
placed. */
* than 10K is actually being used). This is where the kernel code is
* placed. */
portMPU_REGION_BASE_ADDRESS_REG = ( ( uint32_t ) __FLASH_segment_start__ ) | /* Base address. */
( portMPU_REGION_VALID ) |
( portPRIVILEGED_FLASH_REGION );
@ -620,7 +670,7 @@ extern uint32_t __privileged_data_end__;
( portMPU_REGION_ENABLE );
/* 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_VALID ) |
( portPRIVILEGED_RAM_REGION );
@ -631,7 +681,7 @@ extern uint32_t __privileged_data_end__;
( portMPU_REGION_ENABLE );
/* 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_VALID ) |
( portGENERAL_PERIPHERALS_REGION );
@ -654,7 +704,7 @@ static uint32_t prvGetMPURegionSizeSetting( uint32_t ulActualSizeInBytes )
uint32_t ulRegionSize, ulReturnValue = 4;
/* 32 is the smallest region size, 31 is the largest valid value for
ulReturnValue. */
* ulReturnValue. */
for( ulRegionSize = 32UL; ulReturnValue < 31UL; ( ulRegionSize <<= 1UL ) )
{
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
into the the correct bit position of the attribute register. */
* into the the correct bit position of the attribute register. */
return ( ulReturnValue << 1UL );
}
/*-----------------------------------------------------------*/
@ -723,7 +773,7 @@ uint32_t ul;
( portMPU_REGION_ENABLE );
/* 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 =
( ( uint32_t ) __privileged_data_start__ ) | /* Base address. */
( portMPU_REGION_VALID ) |
@ -745,9 +795,9 @@ uint32_t ul;
else
{
/* This function is called automatically when the task is created - in
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
stack region has already been configured. */
* 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
* stack region has already been configured. */
if( ulStackDepth > 0 )
{
/* Define the region that allows access to the stack. */
@ -770,8 +820,8 @@ uint32_t ul;
if( ( xRegions[ lIndex ] ).ulLengthInBytes > 0UL )
{
/* Translate the generic region definition contained in
xRegions into the CM3 specific MPU settings that are then
stored in xMPUSettings. */
* xRegions into the CM3 specific MPU settings that are then
* stored in xMPUSettings. */
xMPUSettings->xRegion[ ul ].ulRegionBaseAddress =
( ( uint32_t ) xRegions[ lIndex ].pvBaseAddress ) |
( portMPU_REGION_VALID ) |
@ -821,47 +871,46 @@ __asm uint32_t prvPortGetIPSR( void )
ucCurrentPriority = pcInterruptPriorityRegisters[ ulCurrentInterrupt ];
/* The following assertion will fail if a service routine (ISR) for
an interrupt that has been assigned a priority above
configMAX_SYSCALL_INTERRUPT_PRIORITY calls an ISR safe FreeRTOS API
function. ISR safe FreeRTOS API functions must *only* be called
from interrupts that have been assigned a priority at or below
configMAX_SYSCALL_INTERRUPT_PRIORITY.
Numerically low interrupt priority numbers represent logically high
interrupt priorities, therefore the priority of the interrupt must
be set to a value equal to or numerically *higher* than
configMAX_SYSCALL_INTERRUPT_PRIORITY.
Interrupts that use the FreeRTOS API must not be left at their
default priority of zero as that is the highest possible priority,
which is guaranteed to be above configMAX_SYSCALL_INTERRUPT_PRIORITY,
and therefore also guaranteed to be invalid.
FreeRTOS maintains separate thread and ISR API functions to ensure
interrupt entry is as fast and simple as possible.
The following links provide detailed information:
http://www.freertos.org/RTOS-Cortex-M3-M4.html
http://www.freertos.org/FAQHelp.html */
* an interrupt that has been assigned a priority above
* configMAX_SYSCALL_INTERRUPT_PRIORITY calls an ISR safe FreeRTOS API
* function. ISR safe FreeRTOS API functions must *only* be called
* from interrupts that have been assigned a priority at or below
* configMAX_SYSCALL_INTERRUPT_PRIORITY.
* Numerically low interrupt priority numbers represent logically high
* interrupt priorities, therefore the priority of the interrupt must
* be set to a value equal to or numerically *higher* than
* configMAX_SYSCALL_INTERRUPT_PRIORITY.
* Interrupts that use the FreeRTOS API must not be left at their
* default priority of zero as that is the highest possible priority,
* which is guaranteed to be above configMAX_SYSCALL_INTERRUPT_PRIORITY,
* and therefore also guaranteed to be invalid.
* FreeRTOS maintains separate thread and ISR API functions to ensure
* interrupt entry is as fast and simple as possible.
* The following links provide detailed information:
* http://www.freertos.org/RTOS-Cortex-M3-M4.html
* http://www.freertos.org/FAQHelp.html */
configASSERT( ucCurrentPriority >= ucMaxSysCallPriority );
}
/* Priority grouping: The interrupt controller (NVIC) allows the bits
that define each interrupt's priority to be split between bits that
define the interrupt's pre-emption priority bits and bits that define
the interrupt's sub-priority. For simplicity all bits must be defined
to be pre-emption priority bits. The following assertion will fail if
this is not the case (if some bits represent a sub-priority).
If the application only uses CMSIS libraries for interrupt
configuration then the correct setting can be achieved on all Cortex-M
devices by calling NVIC_SetPriorityGrouping( 0 ); before starting the
scheduler. Note however that some vendor specific peripheral libraries
assume a non-zero priority group setting, in which cases using a value
of zero will result in unpredicable behaviour. */
* that define each interrupt's priority to be split between bits that
* define the interrupt's pre-emption priority bits and bits that define
* the interrupt's sub-priority. For simplicity all bits must be defined
* to be pre-emption priority bits. The following assertion will fail if
* this is not the case (if some bits represent a sub-priority).
* If the application only uses CMSIS libraries for interrupt
* configuration then the correct setting can be achieved on all Cortex-M
* devices by calling NVIC_SetPriorityGrouping( 0 ); before starting the
* scheduler. Note however that some vendor specific peripheral libraries
* assume a non-zero priority group setting, in which cases using a value
* of zero will result in unpredicable behaviour. */
configASSERT( ( portAIRCR_REG & portPRIORITY_GROUP_MASK ) <= ulMaxPRIGROUPValue );
}
#endif /* configASSERT_DEFINED */
/*-----------------------------------------------------------*/

19
FreeRTOS/Source/portable/RVDS/ARM_CM4_MPU/portmacro.h
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@ -73,12 +73,13 @@ typedef unsigned long UBaseType_t;
#define portUSING_MPU_WRAPPERS 1
#define portPRIVILEGE_BIT ( 0x80000000UL )
#define portMPU_REGION_READ_WRITE ( 0x03UL << 24UL )
#define portMPU_REGION_PRIVILEGED_READ_ONLY ( 0x05UL << 24UL )
#define portMPU_REGION_READ_ONLY ( 0x06UL << 24UL )
#define portMPU_REGION_PRIVILEGED_READ_WRITE ( 0x01UL << 24UL )
#define portMPU_REGION_CACHEABLE_BUFFERABLE ( 0x07UL << 16UL )
#define portMPU_REGION_EXECUTE_NEVER ( 0x01UL << 28UL )
#define portMPU_REGION_READ_WRITE ( 0x03UL << 24UL )
#define portMPU_REGION_PRIVILEGED_READ_ONLY ( 0x05UL << 24UL )
#define portMPU_REGION_READ_ONLY ( 0x06UL << 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_EXECUTE_NEVER ( 0x01UL << 28UL )
#define portUNPRIVILEGED_FLASH_REGION ( 0UL )
#define portPRIVILEGED_FLASH_REGION ( 1UL )
@ -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
}
#endif

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