error: use __INITIAL_SP from cmsis instead of RTX one

[0xc0170]

Summary of changes

We used to require INITIAL_SP as rtx target headers define it. This should not be required, as
cmsis already defines symbol __INITIAL_SP for all toolchains.

Fixes #14432

We have platform/tests/TESTS/mbed_platform/error_handling/main.cpp but that does not probably contain any config in our CI to run with these enabled:

"platform.error-all-threads-info": true,
"platform.stack-dump-enabled": true,

Impact of changes

Migration actions required

Documentation

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Pull request type

[x] Patch update (Bug fix / Target update / Docs update / Test update / Refactor)
[] Feature update (New feature / Functionality change / New API)
[] Major update (Breaking change E.g. Return code change / API behaviour change)

---

Test results

[x] No Tests required for this change (E.g docs only update)
[] Covered by existing mbed-os tests (Greentea or Unittest)
[] Tests / results supplied as part of this PR

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Reviewers

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[ciarmcom]

@0xc0170, thank you for your changes.
@ARMmbed/mbed-os-maintainers please review.

[rotu]

I'm not getting this to build under ARMC6. User error?

mbed compile -t arm --profile debug  
[mbed] Working path "/home/dan/Mbed Programs/ng-robot-firmware" (program)
Building project ng-robot-firmware (NUCLEO_H743ZI2, ARMC6)
Scan: ng-robot-firmware
Using ROM region application in this build.
  Region application: size 0x200000, offset 0x8000000
Using RAM region application_ram in this build.
  Region application_ram: size 0x80000, offset 0x24000000
Compile [ 41.7%]: mbed_printf_armlink_overrides.c
Compile [ 42.0%]: mbed_printf_implementation.c
Compile [ 42.3%]: mbed_stats.c
Compile [ 42.6%]: mbed_wait_api_no_rtos.c
Compile [ 42.9%]: mbed_sdk_boot.c
Compile [ 43.2%]: mbed_semihost_api.c
Compile [ 43.5%]: mbed_printf_wrapper.c
Compile [ 43.8%]: mbed_error.c
[Error] mbed_error.c@522,41: use of undeclared identifier 'Image$$ARM_LIB_STACK$$ZI$$Limit'
[Error] mbed_error.c@522,41: use of undeclared identifier 'Image$$ARM_LIB_STACK$$ZI$$Limit'
[ERROR] ./mbed-os/platform/source/mbed_error.c:522:41: error: use of undeclared identifier 'Image$$ARM_LIB_STACK$$ZI$$Limit'
        uint32_t msp_size = MAX(0, (int)__INITIAL_SP - (int)msp_sp);
                                        ^
./mbed-os/cmsis/CMSIS_5/CMSIS/TARGET_CORTEX_M/Include/cmsis_armclang.h:124:35: note: expanded from macro '__INITIAL_SP'
#define __INITIAL_SP              Image$$ARM_LIB_STACK$$ZI$$Limit
                                  ^
./mbed-os/platform/source/mbed_error.c:522:41: error: use of undeclared identifier 'Image$$ARM_LIB_STACK$$ZI$$Limit'
./mbed-os/cmsis/CMSIS_5/CMSIS/TARGET_CORTEX_M/Include/cmsis_armclang.h:124:35: note: expanded from macro '__INITIAL_SP'
#define __INITIAL_SP              Image$$ARM_LIB_STACK$$ZI$$Limit
                                  ^
2 errors generated.

[mbed] ERROR: "/home/dan/.config/Mbed Studio/mbed-studio-tools/python/bin/python" returned error.
       Code: 1
       Path: "/home/dan/Mbed Programs/ng-robot-firmware"
       Command: "/home/dan/.config/Mbed Studio/mbed-studio-tools/python/bin/python -u /home/dan/Mbed Programs/ng-robot-firmware/mbed-os/tools/make.py -t arm -m NUCLEO_H743ZI2 --profile debug --source . --build ./BUILD/NUCLEO_H743ZI2/ARM-DEBUG"
       Tip: You could retry the last command with "-v" flag for verbose output
---

[rotu]

Maybe should be #define __INITIAL_SP __builtin___get_unsafe_stack_top() for armclang?

doesn't work. No idea what it should be.

[0xc0170]

We might have some targets that do not define the required symbols? I'll check NUCLEO_H743ZI2 first and then more targets.

Pull request has been modified.

[0xc0170]

I believe I fixed it. It was not marked as being extern symbol so compiler could not find it's definition but I've checked and the linker files should provide these.

I've tested both toolchains, no errors.

[0xc0170]

I run CI to check more targets

[mbed-ci]

Jenkins CI Test : ✔️ SUCCESS

Build Number: 1 | 🔒 Jenkins CI Job | 🌐 Logs & Artifacts

CLICK for Detailed Summary

jobs	Status
jenkins-ci/mbed-os-ci_unittests	✔️
jenkins-ci/mbed-os-ci_cmake-cloud-example-GCC_ARM	✔️
jenkins-ci/mbed-os-ci_build-cloud-example-ARM	✔️
jenkins-ci/mbed-os-ci_build-cloud-example-GCC_ARM	✔️
jenkins-ci/mbed-os-ci_cmake-cloud-example-ARM	✔️
jenkins-ci/mbed-os-ci_build-greentea-ARM	✔️
jenkins-ci/mbed-os-ci_cmake-example-GCC_ARM	✔️
jenkins-ci/mbed-os-ci_cmake-example-ARM	✔️
jenkins-ci/mbed-os-ci_build-greentea-GCC_ARM	✔️
jenkins-ci/mbed-os-ci_build-example-GCC_ARM	✔️
jenkins-ci/mbed-os-ci_build-example-ARM	✔️
jenkins-ci/mbed-os-ci_greentea-test	✔️

[rotu]

It works!

[0xc0170]

As it was already approved, I'll merge this