Non Rtos build fails for ARM compiler

[deepikabhavnani]

Description

Mbed OS example when built without rtos, fails in init for ARM compiler.
++ MbedOS Error Info ++
Error Status: 0x80FF013D Code: 317 Module: 255
Error Message: Fault exception
Location: 0x51DB
Error Value: 0x12E6
For more info, visit: https://armmbed.github.io/mbedos-error/?error=0x80FF013D
-- MbedOS Error Info -
++ MbedOS Fault Handler ++

FaultType: HardFault

Context:
R0 : 000073EC
R1 : 00000000
R2 : 000083EC
R3 : 20000104
R4 : 000083EC
R5 : 000073EC
R6 : 000073FC
R7 : 200005DC
R8 : 00000000
R9 : 00000000
R10 : 000071AC
R11 : 000071AC
R12 : 00000000
SP : 2002FFD0
LR : 000012CF
PC : 000012E6
xPSR : 41000000
PSP : 00000000
MSP : 2002FF68
CPUID: 410FC241
HFSR : 40000000
MMFSR: 00000000
BFSR : 00000086
UFSR : 00000000
DFSR : 00000008
AFSR : 00000000
BFAR : 000073EC
Mode : Thread
Priv : Privileged
Stack: MSP

Crash location = __Heap_Initialize
Caller location = _init_alloc

Steps to compile non-rtos version for blinky:

1. mbed import mbed-os-example-blinky
2. Add .mbedignore with following data
   /test/
   mbed-os/rtos/*
   mbed-os/events/*
   mbed-os/features/*
   mbed-os/components/*
3. Remove mbed_app.json - or set all configs as false.

Issue gets fixed with below change in linker file:

diff --git a/targets/TARGET_Freescale/TARGET_MCUXpresso_MCUS/TARGET_MCU_K64F/device/TOOLCHAIN_ARM_STD/MK64FN1M0xxx12.sct b/targets/TARGET_Freescale/TARGET_MCUXpresso_MCUS/TARGET_MCU_K64F/device/TOOLCHAIN_ARM_STD/MK64FN1M0xxx12.sct
index 72a6efafe2..3a92ddf5b1 100644
--- a/targets/TARGET_Freescale/TARGET_MCUXpresso_MCUS/TARGET_MCU_K64F/device/TOOLCHAIN_ARM_STD/MK64FN1M0xxx12.sct
+++ b/targets/TARGET_Freescale/TARGET_MCUXpresso_MCUS/TARGET_MCU_K64F/device/TOOLCHAIN_ARM_STD/MK64FN1M0xxx12.sct
@@ -131,6 +131,4 @@ LR_IROM1 m_interrupts_start m_text_start+m_text_size-m_interrupts_start {   ; lo
   }
   RW_IRAM1 ImageLimit(RW_m_data_2) { ; Heap region growing up
   }
-  ARM_LIB_STACK m_data_2_start+m_data_2_size EMPTY -Stack_Size { ; Stack region growing down
-  }
 }

Linker file was updated to have stack config option and later use it to have unified stack size across all targets.

Solution:

Correct the implementation of _mbed_user_setup_stackheap which assumes single stack and heap region of IARM1 is present in linker file.

mbed-os/platform/mbed_retarget.cpp

Line 909 in 80c6f5f

extern "C" MBED_WEAK __value_in_regs struct __initial_stackheap _mbed_user_setup_stackheap(uint32_t R0, uint32_t R1, uint32_t R2, uint32_t R3)

We have alternate implementations for few targets, considering stack and heap as separate regions for Mbed 2 as well.

mbed-os/targets/TARGET_RENESAS/TARGET_RZ_A1XX/TARGET_RZ_A1H/device/TOOLCHAIN_ARM_STD/sys.cpp

Line 47 in d2e9136

extern __value_in_regs struct __initial_stackheap _mbed_user_setup_stackheap(uint32_t R0, uint32_t R1, uint32_t R2, uint32_t R3) {

Impact:
#8039 - Affects K64F only and is part of 5.11 release
#9092 - All targets and is for 5,12

Issue request type

[ ] Question
[ ] Enhancement
[X] Bug

[deepikabhavnani]

CC @c1728p9 @geky @SenRamakri @LiyouZhou @sg-

[ciarmcom]

Internal Jira reference: https://jira.arm.com/browse/MBOCUSTRIA-805

[JanneKiiskila]

@adbridge we need this to next patch release, please.

[0xc0170]

@mprse Can you please review?

[mprse]

I'll try to investigate this one and provide the fix.

[mprse]

I was able to reproduce the failure and tried to adapt heap parameters to be consistent with rtos builds:

mbed-os/rtos/TARGET_CORTEX/TOOLCHAIN_ARM_STD/mbed_boot_arm_std.c

Lines 30 to 42 in d1b367f

	#if !defined(ISR_STACK_SIZE)
	extern uint32_t Image$$ARM_LIB_STACK$$ZI$$Base[];
	extern uint32_t Image$$ARM_LIB_STACK$$ZI$$Length[];
	#define ISR_STACK_START ((unsigned char*)Image$$ARM_LIB_STACK$$ZI$$Base)
	#define ISR_STACK_SIZE ((uint32_t)Image$$ARM_LIB_STACK$$ZI$$Length)
	#endif
	#if !defined(HEAP_START)
	/* Defined by linker script */
	extern uint32_t Image$$RW_IRAM1$$ZI$$Limit[];
	#define HEAP_START ((unsigned char*)Image$$RW_IRAM1$$ZI$$Limit)
	#define HEAP_SIZE ((uint32_t)((uint32_t)ISR_STACK_START - (uint32_t)HEAP_START))
	#endif

Current version:

extern "C" char Image$$RW_IRAM1$$ZI$$Limit[];
extern "C" char Image$$ARM_LIB_STACK$$ZI$$Base[];
extern "C" char Image$$ARM_LIB_STACK$$ZI$$Length[];

extern "C" MBED_WEAK __value_in_regs struct __initial_stackheap _mbed_user_setup_stackheap(uint32_t R0, uint32_t R1, uint32_t R2, uint32_t R3)
{
    uint32_t zi_limit = (uint32_t)Image$$RW_IRAM1$$ZI$$Limit;
    uint32_t sp_limit = (uint32_t)Image$$ARM_LIB_STACK$$ZI$$Base;

    zi_limit = (zi_limit + 7) & ~0x7;    // ensure zi_limit is 8-byte aligned

    struct __initial_stackheap r;
    r.heap_base = zi_limit;
    r.heap_limit = sp_limit;
	
    return r;
}

It looks like heap parameters should be valid, but I'm still getting hard fault:

-- MbedOS Fault Handler --



++ MbedOS Error Info ++
Error Status: 0x80FF013D Code: 317 Module: 255
Error Message: Fault exception
Location: 0x51CB
Error Value: 0x12E6
For more info, visit: https://armmbed.github.io/mbedos-error/?error=0x80FF013D
-- MbedOS Error Info -▒
++ MbedOS Fault Handler ++

FaultType: HardFault

Context:
R0   : 000073DC
R1   : 00000000
R2   : 000083DC
R3   : 20000104
R4   : 000083DC
R5   : 000073DC
R6   : 000073EC
R7   : 200005DC
R8   : 00000000
R9   : 00000000
R10  : 0000719C
R11  : 0000719C
R12  : 00000000
SP   : 2002FFD0
LR   : 000012CF
PC   : 000012E6
xPSR : 41000000
PSP  : 00000000
MSP  : 2002FF68
CPUID: 410FC241
HFSR : 40000000
MMFSR: 00000000
BFSR : 00000086
UFSR : 00000000
DFSR : 00000008
AFSR : 00000000
BFAR : 000073DC
Mode : Thread
Priv : Privileged
Stack: MSP

@deepikabhavnani Do you maybe have some idea?

[deepikabhavnani]

@mprse - Implementation of __rt_lib_init might be needed as well.

mbed-os/targets/TARGET_RENESAS/TARGET_RZ_A1XX/TARGET_RZ_A1H/device/TOOLCHAIN_ARM_STD/sys.cpp

Line 84 in d2e9136

* The overriding __rt_lib_init is needed only for rtos-less code. For rtos code, __rt_entry is

More Info:
http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dai0179b/CHDEGGBA.html

With addition of ARM_LIB_STACK in linker file we are changing the memory model for RTOS-less builds to 2-region memory model. This needs approval from @sg-

[deepikabhavnani]

@adbridge we need this to next patch release, please.

@ARMmbed/mbed-os-maintainers - Please note the versions when adding the fix. Currently it will fail for all targets on master, since 8039 and 9092 are merged on master.

#8039 affects K64F and was part of 5.11 release, so local fix for K64F can be part of next patch release.
#9092 affects rest of the targets and is for 5.12, so fix for this should be part of 5.12 and not patch release.

[cmonr]

@bulislaw ^^^

[mprse]

@deepikabhavnani Thanks for link and experimentation of the problem.

Fix can be found here: #9571

I checked that blinky example(rtos-less build) works with this patch. I also removed redundant files for targets which have already used 2-region memory model (as it is now common). The only difference is that these targets defines also ARM_LIB_HEAP region. I added exception for these targets. Please review if such solution is acceptable.