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Updates to CM4_MPU GCC 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.
This commit is contained in:
Gaurav Aggarwal 2019-12-20 02:05:44 +00:00
parent c07f60c383
commit 47d8ac6ac6
2 changed files with 110 additions and 22 deletions
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96
FreeRTOS/Source/portable/GCC/ARM_CM4_MPU/port.c
View file

@ -134,7 +134,7 @@ void vPortSetupTimerInterrupt( void );
* Standard FreeRTOS exception handlers. * Standard FreeRTOS exception handlers.
*/ */
void xPortPendSVHandler( void ) __attribute__ (( naked )) PRIVILEGED_FUNCTION; void xPortPendSVHandler( void ) __attribute__ (( naked )) PRIVILEGED_FUNCTION;
void xPortSysTickHandler( void ) __attribute__ ((optimize("3"))) PRIVILEGED_FUNCTION; void xPortSysTickHandler( void ) PRIVILEGED_FUNCTION;
void vPortSVCHandler( void ) __attribute__ (( naked )) PRIVILEGED_FUNCTION; void vPortSVCHandler( void ) __attribute__ (( naked )) PRIVILEGED_FUNCTION;
/* /*
@ -260,10 +260,25 @@ void vPortSVCHandler( void )
static void prvSVCHandler( uint32_t *pulParam ) static void prvSVCHandler( uint32_t *pulParam )
{ {
uint8_t ucSVCNumber; uint8_t ucSVCNumber;
uint32_t ulPC;
#if( configENFORCE_SYSTEM_CALLS_FROM_KERNEL_ONLY == 1 )
#if defined( __ARMCC_VERSION )
/* Declaration when these variable are defined in code instead of being
* exported from linker scripts. */
extern uint32_t * __syscalls_flash_start__;
extern uint32_t * __syscalls_flash_end__;
#else
/* Declaration when these variable are exported from linker scripts. */
extern uint32_t __syscalls_flash_start__[];
extern uint32_t __syscalls_flash_end__[];
#endif /* #if defined( __ARMCC_VERSION ) */
#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 ];
/* 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 ];
switch( ucSVCNumber ) switch( ucSVCNumber )
{ {
case portSVC_START_SCHEDULER : portNVIC_SYSPRI1_REG |= portNVIC_SVC_PRI; case portSVC_START_SCHEDULER : portNVIC_SYSPRI1_REG |= portNVIC_SVC_PRI;
@ -280,6 +295,23 @@ uint8_t ucSVCNumber;
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 volatile
(
" mrs r1, control \n" /* Obtain current control value. */
" bic r1, #1 \n" /* Set privilege bit. */
" msr control, r1 \n" /* Write back new control value. */
::: "r1", "memory"
);
}
break;
#else
case portSVC_RAISE_PRIVILEGE : __asm volatile case portSVC_RAISE_PRIVILEGE : __asm volatile
( (
" mrs r1, control \n" /* Obtain current control value. */ " mrs r1, control \n" /* Obtain current control value. */
@ -288,6 +320,7 @@ uint8_t ucSVCNumber;
::: "r1", "memory" ::: "r1", "memory"
); );
break; break;
#endif /* #if( configENFORCE_SYSTEM_CALLS_FROM_KERNEL_ONLY == 1 ) */
default : /* Unknown SVC call. */ default : /* Unknown SVC call. */
break; break;
@ -307,9 +340,23 @@ static void prvRestoreContextOfFirstTask( void )
" ldr r1, [r3] \n" " ldr r1, [r3] \n"
" ldr r0, [r1] \n" /* The first item in the TCB is the task top of stack. */ " ldr r0, [r1] \n" /* The first item in the TCB is the task top of stack. */
" add r1, r1, #4 \n" /* Move onto the second item in the TCB... */ " add r1, r1, #4 \n" /* Move onto the second item in the TCB... */
" \n"
" dmb \n" /* Complete outstanding transfers before disabling MPU. */
" ldr r2, =0xe000ed94 \n" /* MPU_CTRL register. */
" ldr r3, [r2] \n" /* Read the value of MPU_CTRL. */
" bic r3, #1 \n" /* r3 = r3 & ~1 i.e. Clear the bit 0 in r3. */
" str r3, [r2] \n" /* Disable MPU. */
" \n"
" ldr r2, =0xe000ed9c \n" /* Region Base Address register. */ " ldr r2, =0xe000ed9c \n" /* Region Base Address register. */
" ldmia r1!, {r4-r11} \n" /* Read 4 sets of MPU registers. */ " ldmia r1!, {r4-r11} \n" /* Read 4 sets of MPU registers from TCB. */
" stmia r2!, {r4-r11} \n" /* Write 4 sets of MPU registers. */ " stmia r2!, {r4-r11} \n" /* Write 4 sets of MPU registers. */
" \n"
" ldr r2, =0xe000ed94 \n" /* MPU_CTRL register. */
" ldr r3, [r2] \n" /* Read the value of MPU_CTRL. */
" orr r3, #1 \n" /* r3 = r3 | 1 i.e. Set the bit 0 in r3. */
" str r3, [r2] \n" /* Enable MPU. */
" dsb \n" /* Force memory writes before continuing. */
" \n"
" ldmia r0!, {r3-r11, r14} \n" /* Pop the registers that are not automatically saved on exception entry. */ " ldmia r0!, {r3-r11, r14} \n" /* Pop the registers that are not automatically saved on exception entry. */
" msr control, r3 \n" " msr control, r3 \n"
" msr psp, r0 \n" /* Restore the task stack pointer. */ " msr psp, r0 \n" /* Restore the task stack pointer. */
@ -506,9 +553,23 @@ void xPortPendSVHandler( void )
" ldr r1, [r3] \n" " ldr r1, [r3] \n"
" ldr r0, [r1] \n" /* The first item in the TCB is the task top of stack. */ " ldr r0, [r1] \n" /* The first item in the TCB is the task top of stack. */
" add r1, r1, #4 \n" /* Move onto the second item in the TCB... */ " add r1, r1, #4 \n" /* Move onto the second item in the TCB... */
" \n"
" dmb \n" /* Complete outstanding transfers before disabling MPU. */
" ldr r2, =0xe000ed94 \n" /* MPU_CTRL register. */
" ldr r3, [r2] \n" /* Read the value of MPU_CTRL. */
" bic r3, #1 \n" /* r3 = r3 & ~1 i.e. Clear the bit 0 in r3. */
" str r3, [r2] \n" /* Disable MPU. */
" \n"
" ldr r2, =0xe000ed9c \n" /* Region Base Address register. */ " ldr r2, =0xe000ed9c \n" /* Region Base Address register. */
" ldmia r1!, {r4-r11} \n" /* Read 4 sets of MPU registers. */ " ldmia r1!, {r4-r11} \n" /* Read 4 sets of MPU registers from TCB. */
" stmia r2!, {r4-r11} \n" /* Write 4 sets of MPU registers. */ " stmia r2!, {r4-r11} \n" /* Write 4 sets of MPU registers. */
" \n"
" ldr r2, =0xe000ed94 \n" /* MPU_CTRL register. */
" ldr r3, [r2] \n" /* Read the value of MPU_CTRL. */
" orr r3, #1 \n" /* r3 = r3 | 1 i.e. Set the bit 0 in r3. */
" str r3, [r2] \n" /* Enable MPU. */
" dsb \n" /* Force memory writes before continuing. */
" \n"
" ldmia r0!, {r3-r11, r14} \n" /* Pop the registers that are not automatically saved on exception entry. */ " ldmia r0!, {r3-r11, r14} \n" /* Pop the registers that are not automatically saved on exception entry. */
" msr control, r3 \n" " msr control, r3 \n"
" \n" " \n"
@ -576,12 +637,22 @@ static void vPortEnableVFP( void )
static void prvSetupMPU( void ) static void prvSetupMPU( void )
{ {
#if defined( __ARMCC_VERSION )
/* Declaration when these variable are defined in code instead of being
* exported from linker scripts. */
extern uint32_t * __privileged_functions_end__;
extern uint32_t * __FLASH_segment_start__;
extern uint32_t * __FLASH_segment_end__;
extern uint32_t * __privileged_data_start__;
extern uint32_t * __privileged_data_end__;
#else
/* Declaration when these variable are exported from linker scripts. */
extern uint32_t __privileged_functions_end__[]; extern uint32_t __privileged_functions_end__[];
extern uint32_t __FLASH_segment_start__[]; extern uint32_t __FLASH_segment_start__[];
extern uint32_t __FLASH_segment_end__[]; extern uint32_t __FLASH_segment_end__[];
extern uint32_t __privileged_data_start__[]; extern uint32_t __privileged_data_start__[];
extern uint32_t __privileged_data_end__[]; extern uint32_t __privileged_data_end__[];
#endif
/* Check the expected MPU is present. */ /* Check the expected MPU is present. */
if( portMPU_TYPE_REG == portEXPECTED_MPU_TYPE_VALUE ) if( portMPU_TYPE_REG == portEXPECTED_MPU_TYPE_VALUE )
{ {
@ -693,10 +764,21 @@ void vResetPrivilege( void ) /* __attribute__ (( naked )) */
void vPortStoreTaskMPUSettings( xMPU_SETTINGS *xMPUSettings, const struct xMEMORY_REGION * const xRegions, StackType_t *pxBottomOfStack, uint32_t ulStackDepth ) void vPortStoreTaskMPUSettings( xMPU_SETTINGS *xMPUSettings, const struct xMEMORY_REGION * const xRegions, StackType_t *pxBottomOfStack, uint32_t ulStackDepth )
{ {
#if defined( __ARMCC_VERSION )
/* Declaration when these variable are defined in code instead of being
* exported from linker scripts. */
extern uint32_t * __SRAM_segment_start__;
extern uint32_t * __SRAM_segment_end__;
extern uint32_t * __privileged_data_start__;
extern uint32_t * __privileged_data_end__;
#else
/* Declaration when these variable are exported from linker scripts. */
extern uint32_t __SRAM_segment_start__[]; extern uint32_t __SRAM_segment_start__[];
extern uint32_t __SRAM_segment_end__[]; extern uint32_t __SRAM_segment_end__[];
extern uint32_t __privileged_data_start__[]; extern uint32_t __privileged_data_start__[];
extern uint32_t __privileged_data_end__[]; extern uint32_t __privileged_data_end__[];
#endif
int32_t lIndex; int32_t lIndex;
uint32_t ul; uint32_t ul;

6
FreeRTOS/Source/portable/GCC/ARM_CM4_MPU/portmacro.h
View file

@ -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 )
@ -293,6 +294,11 @@ portFORCE_INLINE static void vPortSetBASEPRI( uint32_t ulNewMaskValue )
#define portMEMORY_BARRIER() __asm volatile( "" ::: "memory" ) #define portMEMORY_BARRIER() __asm volatile( "" ::: "memory" )
#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