Am 19.11.20 um 08:19 schrieb Sebastian Huber:
On 18/11/2020 15:45, Christian Mauderer wrote:
+/**
+ * Higher level region configuration.
+ *
+ * Allows to configure with begin and end which is more convenient for
+ * calculating the sizes from linker command file. Note that you
still have to
+ * follow the following rules:
+ *
+ * - Begin address has to be aligned to 0x20 (lower 5 bits set to 0)
+ * - Sizes can only be a value of 2^x with a minimum of 32 Byte. If
you have an
+ * end address that is not aligned, the region will get bigger.
+ * - Later regions have higher priority.
+ */
+typedef struct {
+ const void *begin;
+ const void *end;
+ uint32_t flags;
uint32_t rasr;
I guess the flags are actually a value stored directly to the RASR?
+} ARMV7M_MPU_Region_Config;
ARMV7M_MPU_Region_config
+
typedef struct {
uint32_t dhcsr;
uint32_t dcrsr;
@@ -611,6 +632,85 @@ void _ARMV7M_Supervisor_call( void );
void _ARMV7M_Clock_handler( void );
+static inline uint32_t _ARMV7M_MPU_get_region_size(uintptr_t size)
_ARMV7M_MPU_Get_region_size
+{
+ if ((size & (size - 1)) == 0) {
+ return ARMV7M_MPU_RASR_SIZE(30 - __builtin_clz(size));
+ } else {
+ return ARMV7M_MPU_RASR_SIZE(31 - __builtin_clz(size));
+ }
+}
+
+static inline void _ARMV7M_MPU_set_region(
_ARMV7M_MPU_Set_region
+ volatile ARMV7M_MPU *mpu,
+ uint32_t region,
+ uint32_t rasr,
+ const void *begin,
+ const void *end
+)
+{
+ uintptr_t size;
+ uint32_t rbar;
+
+ RTEMS_OBFUSCATE_VARIABLE(begin);
+ RTEMS_OBFUSCATE_VARIABLE(end);
+ size = (uintptr_t) end - (uintptr_t) begin;
+
+ if ( size > 0 ) {
+ rbar = (uintptr_t) begin | region | ARMV7M_MPU_RBAR_VALID;
+ rasr |= _ARMV7M_MPU_get_region_size(size);
+ } else {
+ rbar = region;
+ rasr = 0;
+ }
+
+ mpu->rbar = rbar;
+ mpu->rasr = rasr;
+}
+
+static inline void _ARMV7M_MPU_disable_region(
_ARMV7M_MPU_Disable_region
+ volatile ARMV7M_MPU *mpu,
+ uint32_t region
+)
+{
+ mpu->rbar = ARMV7M_MPU_RBAR_VALID | region;
+ mpu->rasr = 0;
+}
+
+static inline void _ARMV7M_MPU_setup_from_config_and_enable(
+ const ARMV7M_MPU_Region_Config *cfg,
+ size_t cfg_count
+)
_ARMV7M_MPU_Setup
The config is implicit in the parameter. You don't necessarily enable a
configured region. It depends on the user provided RASR value.
+{
+ volatile ARMV7M_MPU *mpu;
+ volatile ARMV7M_SCB *scb;
+ uint32_t region_count;
+ uint32_t region;
+
+ mpu = _ARMV7M_MPU;
+ scb = _ARMV7M_SCB;
+
+ region_count = ARMV7M_MPU_TYPE_DREGION_GET(mpu->type);
+
+ if (cfg_count > region_count) {
+ rtems_panic("invalid MPU config");
+ }
I think rtems_panic() is too heavy weight at this point. It uses
printk(). Maybe just use _Assert(). I think we need some light weight
general purpose fatal error which could just use the return address to
identify the error location.
+
+ for (region = 0; region < region_count; ++region) {
for (region = cfg_count; region < region_count; ++region)
Only disable not configured regions?
I think I maybe have to disable the MPU first if I do that. Otherwise it
is possible that there is (for example) a region 0 that prevents access
to all memory and a high region (lets say 5) that allows access to
program memory. As soon as I clear the high one but not the low one, the
system will crash because it can't access the memory any more.
But most likely a similar situation can be constructed with cleaning all
regions. I'll take a look at disabling MPU before setting it up.
+ _ARMV7M_MPU_disable_region(mpu, region);
+ }
+
+ for (region = 0; region < cfg_count; ++region) {
+ _ARMV7M_MPU_set_region(mpu, region, cfg->flags, cfg->begin,
cfg->end);
+ }
+
+ mpu->ctrl = ARMV7M_MPU_CTRL_ENABLE | ARMV7M_MPU_CTRL_PRIVDEFENA;
+ scb->shcsr |= ARMV7M_SCB_SHCSR_MEMFAULTENA;
+
+ _ARM_Data_synchronization_barrier();
+ _ARM_Instruction_synchronization_barrier();
+}
--
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