cmse_check_address_range does not work for CortexM33 code built with ARM CC 6.0

More experiment:

1) Copy arm_cmse.h into project directory, rename it to my_arm_cmse.h

2) Modify cmse_check_address_range(..) by adding a printf statement as below:

static void *
cmse_check_address_range(void *__pb, size_t __s, int __flags) {
uintptr_t __begin = (uintptr_t)__pb;
uintptr_t __end = __begin + __s - 1;
printf("__pb = %p\n", __pb);       //<----------------------- added by me to make sure cmse_check_address_range gets called !!
if (__end < __begin)
return NULL; /* wrap around check */

/* Check whether the range crosses a 32-bytes aligned address */
const int __single_check = (__begin ^ __end) < 0x20u;

..

3) In the main_s.c,  do the following changes to make sure my_arm_cmse.h is included and explicitly define __ARM_FEATURE_CMSE to 3

#include <stdio.h>
//#include <arm_cmse.h>
#define __ARM_FEATURE_CMSE 3
#include "my_arm_cmse.h"

4) When int __attribute__((cmse_nonsecure_entry)) ns_callable_fn1(int x) is executed, I can see the output of "__pb=200000" from  cmse_check_address_range(), but the result of cmse_check_address_range is still wrong, check the disassembly code,  there is no TT instruction generated from intrinsics  cmse_TT/cmse_TTT/cmse_TTA/cmse_TTAT. 

So what causes ARM CC not generating compete assembly code for cmse_check_address_range?

More experiment:

1) Copy arm_cmse.h into project directory, rename it to my_arm_cmse.h

2) Modify cmse_check_address_range(..) by adding a printf statement as below:

static void *
cmse_check_address_range(void *__pb, size_t __s, int __flags) {
uintptr_t __begin = (uintptr_t)__pb;
uintptr_t __end = __begin + __s - 1;
printf("__pb = %p\n", __pb);       //<----------------------- added by me to make sure cmse_check_address_range gets called !!
if (__end < __begin)
return NULL; /* wrap around check */

/* Check whether the range crosses a 32-bytes aligned address */
const int __single_check = (__begin ^ __end) < 0x20u;

..

3) In the main_s.c,  do the following changes to make sure my_arm_cmse.h is included and explicitly define __ARM_FEATURE_CMSE to 3

#include <stdio.h>
//#include <arm_cmse.h>
#define __ARM_FEATURE_CMSE 3
#include "my_arm_cmse.h"

4) When int __attribute__((cmse_nonsecure_entry)) ns_callable_fn1(int x) is executed, I can see the output of "__pb=200000" from  cmse_check_address_range(), but the result of cmse_check_address_range is still wrong, check the disassembly code,  there is no TT instruction generated from intrinsics  cmse_TT/cmse_TTT/cmse_TTA/cmse_TTAT. 

So what causes ARM CC not generating compete assembly code for cmse_check_address_range?

Is this a bug in ARM CC (v6.21 for ADS 2023.1 and v6.18 for ADS 2022.1) which is similar to GCC Bugzilla - Bug 99157 ?

Hi

My name is Stephen and I work at Arm.  Thanks for your interest in Cortex-M33 TrustZone.

I can reproduce what you see with cmse_check_address_range(), and I'm investigating further.

Stephen

Hi again

FYI: your code that calls cmse_check_address_range() didn't compile for me.  
I had to change:
     uint32_t * vRet = 1;
to:
     void * vRet;

An additional flag is required on the call, for example, change:
     vRet = cmse_check_address_range( p, size, CMSE_MPU_NONSECURE);
to:
     vRet = cmse_check_address_range( p, size, CMSE_MPU_NONSECURE | CMSE_MPU_READ );
     
With that change, I see a TTA instruction being generated, and get:
Hello from Non-secure Callable Function 1!
 (00200000, size=4) is entirely in non-secure region!

See developer.arm.com/.../TT-instruction-intrinsics
and
arm-software.github.io/.../cmse.html

Hope this helps

Stephen

Hi Stephen,

Thank you for the supports on this issue.

I tried with flag CMSE_MPU_NONSECURE | CMSE_MPU_READ, and the result was as expected.

The disassembly code for following branch in cms_check_address_range(void *__pb, size_t __s, int __flags) is optimized by AC6 with compiler option "-O1"

...

#if __ARM_CMSE_SECURE_MODE
case CMSE_MPU_NONSECURE:
__permb = cmse_TTA(__pb);
__perme = __single_check ? __permb : cmse_TTA(__pe);
break;
...

If changing to use "-O0", the disassembly code matches with C code even with flags set to CMSE_MPU_NONSECURE only.

This issue can be closed.

Thanks