void cxx_invoke_constructors(void) {
    extern const char _ctors_start, _ctors_end;
    typedef void (*ctor_func_t)(void);
    ctor_func_t *func = (ctor_func_t *) &_ctors_start;
    ....
    for ( ; func != (ctor_func_t *) &_ctors_end; func++) {
        (*func)();
    }
}

int __cxa_atexit(void (*f)(void *), void *objptr, void *dso) {
    if (atexit_func_count >= TABLE_SIZE) {
        printf("__cxa_atexit: static destruction table overflow.\n");
        return -1;
    }
    atexit_funcs[atexit_func_count].destructor_func = f;
    atexit_funcs[atexit_func_count].obj_ptr = objptr;
    atexit_funcs[atexit_func_count].dso_handle = dso;
    atexit_func_count++;
    return 0;
};
void __cxa_finalize(void *f) {
    int i = atexit_func_count;
    if (!f) {
        while (i--) {
            if (atexit_funcs[i].destructor_func) {
                (*atexit_funcs[i].destructor_func)(atexit_funcs[i].obj_ptr);
                atexit_funcs[i].destructor_func = 0;
            }
        }
        atexit_func_count = 0;
    } else {
        for ( ; i >= 0; --i) {
            if (atexit_funcs[i].destructor_func == f) {
                (*atexit_funcs[i].destructor_func)(atexit_funcs[i].obj_ptr);
                atexit_funcs[i].destructor_func = 0;
            }
        }
    }
}
void cxx_invoke_destructors(void) {
    extern const char _dtors_start, _dtors_end;
    typedef void (*dtor_func_t)(void);
    dtor_func_t *func = ((dtor_func_t *) &_dtors_end) - 1;
    /* There are two possible ways for destructors to be calls:
     * 1. Through callbacks registered with __cxa_atexit.
     * 2. From .fini_array section.  */
    /* Handle callbacks registered with __cxa_atexit first, if any.*/
    __cxa_finalize(0);
    /* Handle .fini_array, if any. Functions are executed in teh reverse order. */
    for ( ; func >= (dtor_func_t *) &_dtors_start; func--) {
        (*func)();
    }
}

/**
* @brief Register destructor for a global object
*
* @param destructor the global object destructor function
* @param objptr global object pointer
* @param dso Dynamic Shared Object handle for shared libraries
*
* Function does nothing at the moment, assuming the global objects
* do not need to be deleted
*
* @return N/A
*/
int __cxa_atexit(void (*destructor)(void *), void *objptr, void *dso)
{
    ARG_UNUSED(destructor);
    ARG_UNUSED(objptr);
    ARG_UNUSED(dso);
    return 0;
}

void* operator new(std::size_t size)  throw() {
    void *ptr = NULL;
    if ((ptr = std::malloc(size)) == 0) {
        if (alloc_failure_handler) {
            alloc_failure_handler();
        }
    }
    return ptr;
}
void operator delete(void* ptr) throw() {
    std::free(ptr);
}

void register_eh_frame(void) {
    extern const char _eh_frame_begin;
    __register_frame((void *)&_eh_frame_begin);
}

.ARM.exidx : {
        __exidx_start = .;
        KEEP(*(.ARM.exidx*));
        __exidx_end = .;
    } SECTION_REGION(text)
    .ARM.extab : {
        KEEP(*(.ARM.extab*));
    } SECTION_REGION(text)

extern __EIT_entry __exidx_start;
extern __EIT_entry __exidx_end;

$ arm-none-eabi-gcc -v
Using built-in specs.
COLLECT_GCC=arm-none-eabi-gcc
COLLECT_LTO_WRAPPER=/home/alexander/apt/gcc-arm-none-eabi-9-2020-q2-update/bin/../lib/gcc/arm-none-eabi/9.3.1/lto-wrapper
Target: arm-none-eabi
Configured with: ***     --with-gnu-as --with-gnu-ld --with-newlib   ***
Thread model: single
gcc version 9.3.1 20200408 (release) (GNU Arm Embedded Toolchain 9-2020-q2-update)

struct _reent {
    int _errno;           /* local copy of errno */
  /* FILE is a big struct and may change over time.  To try to achieve binary
     compatibility with future versions, put stdin,stdout,stderr here.
     These are pointers into member __sf defined below.  */
    FILE *_stdin, *_stdout, *_stderr;
};
struct _reent global_newlib_reent;
void *_impure_ptr = &global_newlib_reent;
static int reent_init(void) {
    global_newlib_reent._stdin = stdin;
    global_newlib_reent._stdout = stdout;
    global_newlib_reent._stderr = stderr;
    return 0;
}

$ arm-none-eabi-gcc -v
***
Thread model: single
gcc version 9.3.1 20200408 (release) (GNU Arm Embedded Toolchain 9-2020-q2-update)