How to enterd Privileged Mode ?

Hello Arrly,

  The HalCoGen generates the device startup file where it will put the device into SYSTEM privileged mode. In the sys_core.asm you will find the _coreInitRegisters_() function where the core registers are initialized in different CPU operating modes. The _coreInitRegisters_() is called in the sys_startup.c in the very beginning. For further information about privileged mode please refer to the Cortex-R4F TRM and look under 2.3 Operating modes section.

;-------------------------------------------------------------------------------
; Initialize CPU Registers
; SourceId : CORE_SourceId_001
; DesignId : CORE_DesignId_001
; Requirements: HL_SR477, HL_SR476, HL_SR492

    .def     _coreInitRegisters_
    .asmfunc


_coreInitRegisters_


    ; After reset, the CPU is in the Supervisor mode (M = 10011)
        mov r0, lr
        mov r1, #0x0000
        mov r2, #0x0000
        mov r3, #0x0000
        mov r4, #0x0000
        mov r5, #0x0000
        mov r6, #0x0000
        mov r7, #0x0000
        mov r8, #0x0000
        mov r9, #0x0000
        mov r10, #0x0000
        mov r11, #0x0000
        mov r12, #0x0000
        mov r13, #0x0000
        mrs r1, cpsr
        msr spsr_cxsf, r1
        ; Switch to FIQ mode (M = 10001)
        cps #17
        mov lr, r0
        mov r8, #0x0000
        mov r9, #0x0000
        mov r10, #0x0000
        mov r11, #0x0000
        mov r12, #0x0000
        mrs r1, cpsr
        msr spsr_cxsf, r1
        ; Switch to IRQ mode (M = 10010)
        cps #18
        mov lr, r0
        mrs r1,cpsr
        msr spsr_cxsf, r1
        ; Switch to Abort mode (M = 10111)
        cps #23
        mov lr, r0
        mrs r1,cpsr
        msr spsr_cxsf, r1
        ; Switch to Undefined Instruction Mode (M = 11011)
        cps #27
        mov lr, r0
        mrs r1,cpsr
        msr spsr_cxsf, r1
        ; Switch to System Mode ( Shares User Mode registers ) (M = 11111)
        cps #31
        mov lr, r0
        mrs r1,cpsr
        msr spsr_cxsf, r1


        mrc   p15,     #0x00,      r2,       c1, c0, #0x02
        orr   r2,      r2,         #0xF00000
        mcr   p15,     #0x00,      r2,       c1, c0, #0x02
        mov   r2,      #0x40000000
        fmxr  fpexc,   r2

        fmdrr d0,         r1,     r1
        fmdrr d1,         r1,     r1
        fmdrr d2,         r1,     r1
        fmdrr d3,         r1,     r1
        fmdrr d4,         r1,     r1
        fmdrr d5,         r1,     r1
        fmdrr d6,         r1,     r1
        fmdrr d7,         r1,     r1
        fmdrr d8,         r1,     r1
        fmdrr d9,         r1,     r1
        fmdrr d10,        r1,     r1
        fmdrr d11,        r1,     r1
        fmdrr d12,        r1,     r1
        fmdrr d13,        r1,     r1
        fmdrr d14,        r1,     r1
        fmdrr d15,        r1,     r1
        bl    next1
next1
        bl    next2
next2
        bl    next3
next3
        bl    next4
next4
        bx    r0

    .endasmfunc

Also you will likely need to run certain tasks in USER mode to restrict their access to critical memory areas.
Once you enter User mode you cannot simply switch to System or Supervisor mode like is shown above.

From user mode, an exception is required to enter privilege again thus giving a controlled entry point back from User to Privilege.

There are two ways software can initiate this: (a) using an SVC call, which will put you into the SWI handler and into supervisor mode, (b) using the System Software Interrupt of the system module (SSI) which will generate an IRQ interrupt for you and put you into the IRQ mode.