Errors when compile asm file

Hi Mitko,

MSR with an immediate value is an ARM only instruction. Are you using a Cortex-R or Cortex-A processor? If not you need to move the bits first into a register (let's say r0) and then use msr CPSR_c, r0 to load into the CPSR. If you are indeed using an ARM processor having an ARM execution mode, I believe you just have to define the Mode_UND, I_Bit and F_Bit to their hex values.

Best regards,

Thomas

Hi Thomas,

Thanks about the recommendation. The processor is ARM926ej, and I am porting a Keil code to GCC. After fixing the definitions as you recommended - no errors on those lines, but getting the following errors:

../wb_init.s(45): error: internal_relocation (type: OFFSET_IMM) not fixed up

As well as there is this C code that provides errors too (on Keil it compiles with no errors):

__value_in_regs struct R0_R3 {unsigned heap_base, stack_base, heap_limit, stack_limit;}
    __user_initial_stackheap(unsigned int R0, unsigned int SP, unsigned int R2, unsigned int SL)
{
    struct R0_R3 config;

    //config.heap_base = 0x00060000;
    config.heap_base = (unsigned int)&Image$$ZI$$Limit;
    config.stack_base = SP;

/*

../standalone.c(32): error: expected '=', ',', ';', 'asm' or '__attribute__' before 'struct'
../standalone.c: In function '__user_initial_stackheap':
../standalone.c(38): error: 'struct R0_R3' has no member named 'heap_base'
../standalone.c(39): error: 'struct R0_R3' has no member named 'stack_base'

Hi Mitko,

I'm not aware of an exact equivalent to __value_in_regs for GCC but you put an optimize attribute that tells to return the struct un general registers. Note that this is a function attribute so you would need to set it on each function returning this struct R0_R3. This actually quite make sense since this is concern how a function is called and returned from. You would do it this way:

struct R0_R3 {unsigned heap_base, stack_base, heap_limit, stack_limit;}
__user_initial_stackheap (unsigned int R0, unsigned int SP, unsigned int R2, unsigned int SL) __attribute ((optimize ("reg-struct-return")))
{
  struct R0_R3 config;
  // rest of code here
}

As to your relocation error, could you provide us with a simple testcase? I see from the code that this error happens when a section doesn't have rela but would need more info to diagnose more precisely what is the problem.

Best regards,

Thomas

Hi Thomas,

Unfortunately, your recommendation didn't fix the problem, currently getting the following error:

../standalone.c(34): error: expected ',' or ';' before '{' token

32 struct R0_R3 {unsigned heap_base, stack_base, heap_limit, stack_limit;}
33 __user_initial_stackheap (unsigned int R0, unsigned int SP, unsigned int R2, unsigned int SL) __attribute ((optimize ("reg-struct-return")))
34 {
35 struct R0_R3 config;

Regarding the relocation error, I changed the compiler to gcc-arm-none-eabi-4_9-2014q4-20141203 and the relocation error is not shown so far, but getting other types of errors:

../wb_init.s: Assembler messages:
Error: ../wb_init.s: Error: .size expression for Prefetch_Handler does not evaluate to a constant
Error: ../wb_init.s: Error: .size expression for SWI_Handler1 does not evaluate to a constant

# ************************
# Exception Handlers
# ************************

# The following dummy handlers do not do anything useful in this example.
# They are set up here for completeness.

#Undefined_Handler
# B Undefined_Handler
        .weak Undef_Handler
        .type Undef_Handler, %function
Undef_Handler: B Undef_Handler
        .size Undef_Handler, . - Undef_Handler
#SWI_Handler1
# B
        .weak SWI_Handler1
        .type SWI_Handler1, %function
SWI_Handler: B SWI_Handler1
        .size SWI_Handler1, . - SWI_Handler1
#Prefetch_Handler
# B Prefetch_Handler
        .weak Prefetch_Handler
        .type Prefetch_Handler, %function
PAbt_Handler: B Prefetch_Handler
        .size Prefetch_Handler, . - Prefetch_Handler
#Abort_Handler
# B Abort_Handler
        .weak Abort_Handler
        .type Abort_Handler, %function
Abort_Handler: B Abort_Handler
        .size Abort_Handler, . - Abort_Handler
#IRQ_Handler
# B IRQ_Handler
        .weak IRQ_Handler
        .type IRQ_Handler, %function
IRQ_Handler: B IRQ_Handler
        .size IRQ_Handler, . - IRQ_Handler
#FIQ_Handler
# B FIQ_Handler
        .weak FIQ_Handler
        .type FIQ_Handler, %function
FIQ_Handler: B FIQ_Handler
        .size FIQ_Handler, . - FIQ_Handler

I do understand that is quite difficult just to look at some pieces of the code and wondered if you might be willing to look at the whole project if uploaded somewhere ?

Regards,
Mitko

Hi Mitko,

My apologize, I tried the attribute on a prototype where I should have tried on a definition as in the example I gave. For function definition the attribute must be before the return type. Thus the correct example is:

__attribute ((optimize ("reg-struct-return"))) struct R0_R3 {unsigned heap_base, stack_base, heap_limit, stack_limit;}
__user_initial_stackheap (unsigned int R0, unsigned int SP, unsigned int R2, unsigned int SL)
{
  struct R0_R3 config;
  // rest of code here
}

As to the errors you get with .size this is because you didn't declare a label for these symbols. So the assembler doesn't see their address and cannot compute the difference between the current location and the start. You should do something like this:

#Prefetch_Handler
# B Prefetch_Handler
        .weak Prefetch_Handler
        .type Prefetch_Handler, %function
PAbt_Handler: B Prefetch_Handler
Prefetch_Handler:
        .size Prefetch_Handler, . - Prefetch_Handler

Best regards.