/* * Copyright (c) 2006-2022, RT-Thread Development Team * * SPDX-License-Identifier: Apache-2.0 * * Change Logs: * Date Author Notes * 2013-07-05 Bernard the first version */ .equ Mode_USR, 0x10 .equ Mode_FIQ, 0x11 .equ Mode_IRQ, 0x12 .equ Mode_SVC, 0x13 .equ Mode_ABT, 0x17 .equ Mode_UND, 0x1B .equ Mode_SYS, 0x1F .equ I_Bit, 0x80 @ when I bit is set, IRQ is disabled .equ F_Bit, 0x40 @ when F bit is set, FIQ is disabled .equ UND_Stack_Size, 0x00000200 .equ SVC_Stack_Size, 0x00000100 .equ ABT_Stack_Size, 0x00000000 .equ FIQ_Stack_Size, 0x00000000 .equ IRQ_Stack_Size, 0x00000100 .equ USR_Stack_Size, 0x00000100 #define ISR_Stack_Size (UND_Stack_Size + SVC_Stack_Size + ABT_Stack_Size + \ FIQ_Stack_Size + IRQ_Stack_Size) /* stack */ .globl stack_start .globl stack_top .align 3 stack_start: .rept ISR_Stack_Size .long 0 .endr stack_top: /* reset entry */ .globl _reset _reset: /* set the cpu to SVC32 mode and disable interrupt */ mrs r0, cpsr bic r0, r0, #0x1f orr r0, r0, #0x13 msr cpsr_c, r0 /* setup stack */ bl stack_setup /* clear .bss */ mov r0,#0 /* get a zero */ ldr r1,=__bss_start /* bss start */ ldr r2,=__bss_end /* bss end */ bss_loop: cmp r1,r2 /* check if data to clear */ strlo r0,[r1],#4 /* clear 4 bytes */ blo bss_loop /* loop until done */ /* call C++ constructors of global objects */ ldr r0, =__ctors_start__ ldr r1, =__ctors_end__ ctor_loop: cmp r0, r1 beq ctor_end ldr r2, [r0], #4 stmfd sp!, {r0-r1} mov lr, pc bx r2 ldmfd sp!, {r0-r1} b ctor_loop ctor_end: /* start RT-Thread Kernel */ ldr pc, _rtthread_startup _rtthread_startup: .word rtthread_startup stack_setup: ldr r0, =stack_top @ Enter Undefined Instruction Mode and set its Stack Pointer msr cpsr_c, #Mode_UND|I_Bit|F_Bit mov sp, r0 sub r0, r0, #UND_Stack_Size @ Enter Abort Mode and set its Stack Pointer msr cpsr_c, #Mode_ABT|I_Bit|F_Bit mov sp, r0 sub r0, r0, #ABT_Stack_Size @ Enter FIQ Mode and set its Stack Pointer msr cpsr_c, #Mode_FIQ|I_Bit|F_Bit mov sp, r0 sub r0, r0, #FIQ_Stack_Size @ Enter IRQ Mode and set its Stack Pointer msr cpsr_c, #Mode_IRQ|I_Bit|F_Bit mov sp, r0 sub r0, r0, #IRQ_Stack_Size @ Enter Supervisor Mode and set its Stack Pointer msr cpsr_c, #Mode_SVC|I_Bit|F_Bit mov sp, r0 sub r0, r0, #SVC_Stack_Size @ Enter User Mode and set its Stack Pointer mov sp, r0 sub sl, sp, #USR_Stack_Size bx lr /* exception handlers: undef, swi, padt, dabt, resv, irq, fiq */ .align 5 .globl vector_undef vector_undef: sub sp, sp, #72 stmia sp, {r0 - r12} @/* Calling r0-r12 */ add r8, sp, #60 mrs r1, cpsr mrs r2, spsr orr r2,r2, #I_Bit|F_Bit msr cpsr_c, r2 mov r0, r0 stmdb r8, {sp, lr} @/* Calling SP, LR */ msr cpsr_c, r1 @/* return to Undefined Instruction mode */ str lr, [r8, #0] @/* Save calling PC */ mrs r6, spsr str r6, [r8, #4] @/* Save CPSR */ str r0, [r8, #8] @/* Save OLD_R0 */ mov r0, sp bl rt_hw_trap_udef ldmia sp, {r0 - r12} @/* Calling r0 - r2 */ mov r0, r0 ldr lr, [sp, #60] @/* Get PC */ add sp, sp, #72 movs pc, lr @/* return & move spsr_svc into cpsr */ .align 5 .globl vector_swi vector_swi: bl rt_hw_trap_swi .align 5 .globl vector_pabt vector_pabt: bl rt_hw_trap_pabt .align 5 .globl vector_dabt vector_dabt: sub sp, sp, #72 stmia sp, {r0 - r12} @/* Calling r0-r12 */ add r8, sp, #60 stmdb r8, {sp, lr} @/* Calling SP, LR */ str lr, [r8, #0] @/* Save calling PC */ mrs r6, spsr str r6, [r8, #4] @/* Save CPSR */ str r0, [r8, #8] @/* Save OLD_R0 */ mov r0, sp bl rt_hw_trap_dabt ldmia sp, {r0 - r12} @/* Calling r0 - r2 */ mov r0, r0 ldr lr, [sp, #60] @/* Get PC */ add sp, sp, #72 movs pc, lr @/* return & move spsr_svc into cpsr */ .align 5 .globl vector_resv vector_resv: b . .align 5 .globl vector_fiq vector_fiq: stmfd sp!,{r0-r7,lr} bl rt_hw_trap_fiq ldmfd sp!,{r0-r7,lr} subs pc,lr,#4 .globl rt_interrupt_enter .globl rt_interrupt_leave .globl rt_thread_switch_interrupt_flag .globl rt_interrupt_from_thread .globl rt_interrupt_to_thread .globl rt_current_thread .globl vmm_thread .globl vmm_virq_check .globl vector_irq vector_irq: stmfd sp!, {r0-r12,lr} bl rt_interrupt_enter bl rt_hw_trap_irq bl rt_interrupt_leave @ if rt_thread_switch_interrupt_flag set, jump to @ rt_hw_context_switch_interrupt_do and don't return ldr r0, =rt_thread_switch_interrupt_flag ldr r1, [r0] cmp r1, #1 beq rt_hw_context_switch_interrupt_do ldmfd sp!, {r0-r12,lr} subs pc, lr, #4 rt_hw_context_switch_interrupt_do: mov r1, #0 @ clear flag str r1, [r0] ldmfd sp!, {r0-r12,lr}@ reload saved registers stmfd sp, {r0-r2} @ save r0-r2 mrs r0, spsr @ get cpsr of interrupt thread sub r1, sp, #4*3 sub r2, lr, #4 @ save old task's pc to r2 @ switch to SVC mode with no interrupt msr cpsr_c, #I_Bit|F_Bit|Mode_SVC stmfd sp!, {r2} @ push old task's pc stmfd sp!, {r3-r12,lr}@ push old task's lr,r12-r4 ldmfd r1, {r1-r3} @ restore r0-r2 of the interrupt thread stmfd sp!, {r1-r3} @ push old task's r0-r2 stmfd sp!, {r0} @ push old task's cpsr ldr r4, =rt_interrupt_from_thread ldr r5, [r4] str sp, [r5] @ store sp in preempted tasks's TCB ldr r6, =rt_interrupt_to_thread ldr r6, [r6] ldr sp, [r6] @ get new task's stack pointer ldmfd sp!, {r4} @ pop new task's cpsr to spsr msr spsr_cxsf, r4 ldmfd sp!, {r0-r12,lr,pc}^ @ pop new task's r0-r12,lr & pc, copy spsr to cpsr