Memory protection

Description

Memory protection support internals for ARM architecture.

Modules
	ARM MPU CTRL fields
	ARM MPU RASR fields
	ARM MPU RBAR fields
	ARM MPU register aliases
	MPU region names
	Names of ARM MPU regions as being used by CMRX.

Macros
#define	MPU_RNR_REGION   (MPU_RNR_REGION_Msk)
#define	MPU_RNR_REGION_LSB   (MPU_RNR_REGION_Pos)
#define	MPU_AP_MASK   0b0111
#define	MPU_EXECUTE_SHIFT   3

Functions
int	mpu_set_region (uint8_t region, const void *base, uint32_t size, uint8_t cls)
	Configure and activate MPU region.
int	mpu_clear_region (uint8_t region)
	Disable MPU region.
int	mpu_load (const MPU_State *state, uint8_t base, uint8_t count)
static const uint32_t	__MPU_flags []
	MPU region access rights.
int	mpu_configure_region (uint8_t region, const void *base, uint32_t size, uint8_t flags, uint32_t *RBAR, uint32_t *RASR)
	Create configuration for MPU region.
void	hard_fault_handler (void)
	Handler for hard fault.
void	mem_manage_handler (void)
static uint8_t	log_2 (uint32_t num)
void	mpu_enable ()
	Enable memory protection.
void	mpu_disable ()
	Disable memory protection.
int	mpu_store (MPU_State *hosted_state, MPU_State *parent_state)
	Store MPU settings.
int	mpu_restore (const MPU_State *hosted_state, const MPU_State *parent_state)
	Load MPU settings.
uint32_t	__mpu_expand_class (uint8_t class)

Macro Definition Documentation

MPU_AP_MASK

#define MPU_AP_MASK   0b0111

MPU_EXECUTE_SHIFT

#define MPU_EXECUTE_SHIFT   3

MPU_RNR_REGION

#define MPU_RNR_REGION   (MPU_RNR_REGION_Msk)

MPU_RNR_REGION_LSB

#define MPU_RNR_REGION_LSB   (MPU_RNR_REGION_Pos)

Function Documentation

__mpu_expand_class()

uint32_t __mpu_expand_class

(

uint8_t

class

)

hard_fault_handler()

void hard_fault_handler

(

void

)

Handler for hard fault.

log_2()

static uint8_t log_2 ( uint32_t  num )

inlinestatic

mem_manage_handler()

void mem_manage_handler

(

void

)

mpu_clear_region()

int mpu_clear_region

(

uint8_t

region

)

Disable MPU region.

This function will disable use of MPU region. Address and size will remain configured, but region is not marked as enabled anymore.

Parameters

region

ID of region being deactivated (0 - 7)

Returns

E_OK if region was deactivated

mpu_configure_region()

int mpu_configure_region	(	uint8_t	region,
		const void *	base,
		uint32_t	size,
		uint8_t	flags,
		uint32_t *	RBAR,
		uint32_t *	RASR
	)

Create configuration for MPU region.

@TODO

mpu_disable()

void mpu_disable

(

)

Disable memory protection.

This routine will disable memory protection even for unprivileged code.

mpu_enable()

void mpu_enable

(

)

Enable memory protection.

This routine enables memory protection with standard memory setup for kernel purposes. This means that any privileged code has full access to memory as if no memory protection was turned on.

Note

It is safe to call this routine in kernel context even if no memory regions are set.

mpu_load()

int mpu_load	(	const MPU_State *	state,
		uint8_t	base,
		uint8_t	count
	)

mpu_restore()

int mpu_restore	(	const MPU_State *	hosted_state,
		const MPU_State *	parent_state
	)

Load MPU settings.

Loads MPU settings for default amount of regions from off-CPU buffer. This is suitable for store-resume during task switching.

Parameters

state

MPU state buffer

mpu_set_region()

int mpu_set_region	(	uint8_t	region,
		const void *	base,
		uint32_t	size,
		uint8_t	cls
	)

Configure and activate MPU region.

Activate given memory region with new base address and size. For now, caller is responsible for providing base address, which is aligned to size of block. If region is already activated, then its base address, size and flags are being overwritten.

Parameters

region	ID of region being activated (0-7)
base	base address of region
size	size of region (256B and more)
cls	region access class, see MPU_class for available access classes

Returns

E_OK if region was configured, otherwise error code is returned

mpu_store()

int mpu_store	(	MPU_State *	hosted_state,
		MPU_State *	parent_state
	)

Store MPU settings.

Stores MPU settings for default amount of regions into off-CPU buffer. This is suitable for store-resume during task switching.

Parameters

state

MPU state buffer

Variable Documentation

__MPU_flags

const uint32_t __MPU_flags[]

static

Initial value:

= {
    0,
    MPU_RASR_ATTR_AP_PRW_URO,
    MPU_RASR_ATTR_AP_PRW_URW,
    MPU_RASR_ATTR_XN | MPU_RASR_ATTR_AP_PRW_URO,
    MPU_RASR_ATTR_XN | MPU_RASR_ATTR_AP_PRW_URW,
}

MPU region access rights.

This array maps CMRX access modes to ARM access modes See enum MPU_Flags for meaning of individual indices.