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Handle armv8m unpriv_access with SAU #486

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Handle armv8m unpriv_access with SAU #486

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123 changes: 24 additions & 99 deletions core/vmpu/src/mpu_armv8m/vmpu_armv8m_unpriv_access.c
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Original file line number Diff line number Diff line change
Expand Up @@ -15,110 +15,35 @@
* limitations under the License.
*/
#include <uvisor.h>
#include <stdbool.h>
#include "context.h"
#include "debug.h"
#include "vmpu.h"
#include "halt.h"
#include "vmpu_mpu.h"
#include "vmpu_unpriv_access.h"
#include <stdbool.h>

#define TT_RESP_IREGION_Pos 24U
#define TT_RESP_IREGION_Msk (0xFFUL << TT_RESP_IREGION_Pos)

#define TT_RESP_IRVALID_Pos 23U
#define TT_RESP_IRVALID_Msk (1UL << TT_RESP_IRVALID_Pos)

#define TT_RESP_S_Pos 22U
#define TT_RESP_S_Msk (1UL << TT_RESP_S_Pos)

#define TT_RESP_NSRW_Pos 21U
#define TT_RESP_NSRW_Msk (1UL << TT_RESP_NSRW_Pos)

#define TT_RESP_NSR_Pos 20U
#define TT_RESP_NSR_Msk (1UL << TT_RESP_NSR_Pos)

#define TT_RESP_RW_Pos 19U
#define TT_RESP_RW_Msk (1UL << TT_RESP_RW_Pos)

#define TT_RESP_R_Pos 18U
#define TT_RESP_R_Msk (1UL << TT_RESP_R_Pos)

#define TT_RESP_SRVALID_Pos 17U
#define TT_RESP_SRVALID_Msk (1UL << TT_RESP_SRVALID_Pos)

#define TT_RESP_MRVALID_Pos 16U
#define TT_RESP_MRVALID_Msk (1UL << TT_RESP_MRVALID_Pos)

#define TT_RESP_SREGION_Pos 8U
#define TT_RESP_SREGION_Msk (0xFFUL << TT_RESP_SREGION_Pos)

#define TT_RESP_MREGION_Pos 0U
#define TT_RESP_MREGION_Msk (0xFFUL << TT_RESP_MREGION_Pos)


static uint32_t vmpu_unpriv_test_range(uint32_t addr, uint32_t size)
{
if (!size) size = 1;
uint32_t response_lower, response_upper;
uint32_t test_addr_lower = addr & ~31UL;
uint32_t test_addr_upper = (addr + size - 1) & ~31UL;

/* Test lower address. */
asm volatile (
"tta %[response], %[addr]"
: [response] "=r" (response_lower)
: [addr] "r" (test_addr_lower)
);
if (test_addr_lower != test_addr_upper) {
/* Test upper address. */
asm volatile (
"tta %[response], %[addr]"
: [response] "=r" (response_upper)
: [addr] "r" (test_addr_upper)
);
/* If lower and upper do not have the same S|SRVALID|SREGION, then it's definitely not the same region. */
if (((response_lower ^ response_upper) & (TT_RESP_S_Msk | TT_RESP_SRVALID_Msk | TT_RESP_SREGION_Msk))) {
/* Upper memory region has different SAU region than lower memory region! */
return 0;
}
/* Both memory locations have the same non-secure SAU region and therefore same properties.
* No Secure SAU region can be inbetween due to SAU region overlap rules. */
response_lower &= response_upper;
}

return response_lower & (TT_RESP_NSRW_Msk | TT_RESP_NSR_Msk | TT_RESP_RW_Msk | TT_RESP_R_Msk |
TT_RESP_S_Msk | TT_RESP_SRVALID_Msk | TT_RESP_SREGION_Msk);
}

extern int vmpu_fault_recovery_mpu(uint32_t pc, uint32_t sp, uint32_t fault_addr, uint32_t fault_status);

uint32_t vmpu_unpriv_access(uint32_t addr, uint32_t size, uint32_t data)
{
unsigned int tries = 0;
while(1) {
if ((vmpu_unpriv_test_range(addr, UVISOR_UNPRIV_ACCESS_SIZE(size)) & (TT_RESP_NSRW_Msk | TT_RESP_SRVALID_Msk)) == (TT_RESP_NSRW_Msk | TT_RESP_SRVALID_Msk)) {
switch(size) {
case UVISOR_UNPRIV_ACCESS_READ(1):
return *((uint8_t *) addr);
case UVISOR_UNPRIV_ACCESS_READ(2):
return *((uint16_t *) addr);
case UVISOR_UNPRIV_ACCESS_READ(4):
return *((uint32_t *) addr);
case UVISOR_UNPRIV_ACCESS_WRITE(1):
*((uint8_t *) addr) = (uint8_t) data;
return 0;
case UVISOR_UNPRIV_ACCESS_WRITE(2):
*((uint16_t *) addr) = (uint16_t) data;
return 0;
case UVISOR_UNPRIV_ACCESS_WRITE(4):
*((uint32_t *) addr) = data;
return 0;
default:
break;
}
break;
}
if (++tries > 1 || !vmpu_fault_recovery_mpu(0, 0, addr, 0)) {
break;
// This operation could be slow since we are scanning all the regions defined for the box
// an implementation using the TTA command is faster but causes misses since it works with the MPU
if (vmpu_buffer_access_is_ok(g_active_box, (const void *) addr, UVISOR_UNPRIV_ACCESS_SIZE(size))){
switch(size) {
case UVISOR_UNPRIV_ACCESS_READ(1):
return *((uint8_t *) addr);
case UVISOR_UNPRIV_ACCESS_READ(2):
return *((uint16_t *) addr);
case UVISOR_UNPRIV_ACCESS_READ(4):
return *((uint32_t *) addr);
case UVISOR_UNPRIV_ACCESS_WRITE(1):
*((uint8_t *) addr) = (uint8_t) data;
return 0;
case UVISOR_UNPRIV_ACCESS_WRITE(2):
*((uint16_t *) addr) = (uint16_t) data;
return 0;
case UVISOR_UNPRIV_ACCESS_WRITE(4):
*((uint32_t *) addr) = data;
return 0;
default:
break;
}
}
HALT_ERROR(PERMISSION_DENIED, "Access to restricted resource denied");
Expand Down