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rt-thread/libcpu/arm/cortex-a/start_gcc.S

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ArmAsm
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/*
* Copyright (c) 2006-2018, RT-Thread Development Team
*
* SPDX-License-Identifier: Apache-2.0
*
* Change Logs:
* Date Author Notes
* 2013-07-05 Bernard the first version
* 2018-11-22 Jesven in the interrupt context, use rt_scheduler_do_irq_switch checks
* and switches to a new thread
*/
#include "rtconfig.h"
.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, 0x00000400
.equ SVC_Stack_Size, 0x00000400
.equ ABT_Stack_Size, 0x00000400
.equ RT_FIQ_STACK_PGSZ, 0x00000000
.equ RT_IRQ_STACK_PGSZ, 0x00000800
.equ USR_Stack_Size, 0x00000400
.equ SUB_UND_Stack_Size, 0x00000400
.equ SUB_SVC_Stack_Size, 0x00000400
.equ SUB_ABT_Stack_Size, 0x00000400
.equ SUB_RT_FIQ_STACK_PGSZ, 0x00000000
.equ SUB_RT_IRQ_STACK_PGSZ, 0x00000400
.equ SUB_USR_Stack_Size, 0x00000400
#define ISR_Stack_Size (UND_Stack_Size + SVC_Stack_Size + ABT_Stack_Size + \
RT_FIQ_STACK_PGSZ + RT_IRQ_STACK_PGSZ)
#define SUB_ISR_Stack_Size (SUB_UND_Stack_Size + SUB_SVC_Stack_Size + SUB_ABT_Stack_Size + \
SUB_RT_FIQ_STACK_PGSZ + SUB_RT_IRQ_STACK_PGSZ)
.section .data.share.isr
/* stack */
.globl stack_start
.globl stack_top
.align 3
stack_start:
.rept ISR_Stack_Size
.byte 0
.endr
stack_top:
.text
/* reset entry */
.globl _reset
_reset:
#ifdef ARCH_ARMV8
/* Check for HYP mode */
mrs r0, cpsr_all
and r0, r0, #0x1F
mov r8, #0x1A
cmp r0, r8
beq overHyped
b continue
overHyped: /* Get out of HYP mode */
adr r1, continue
msr ELR_hyp, r1
mrs r1, cpsr_all
and r1, r1, #0x1f ;@ CPSR_MODE_MASK
orr r1, r1, #0x13 ;@ CPSR_MODE_SUPERVISOR
msr SPSR_hyp, r1
eret
continue:
#endif
/* set the cpu to SVC32 mode and disable interrupt */
cps #Mode_SVC
#ifdef RT_USING_FPU
mov r4, #0xfffffff
mcr p15, 0, r4, c1, c0, 2
#endif
/* disable the data alignment check */
mrc p15, 0, r1, c1, c0, 0
bic r1, #(1<<0) /* Disable MMU */
bic r1, #(1<<1) /* Disable Alignment fault checking */
bic r1, #(1<<2) /* Disable data cache */
bic r1, #(1<<11) /* Disable program flow prediction */
bic r1, #(1<<12) /* Disable instruction cache */
bic r1, #(3<<19) /* bit[20:19] must be zero */
mcr p15, 0, r1, c1, c0, 0
@ get cpu id, and subtract the offset from the stacks base address
bl rt_hw_cpu_id
mov r5, r0
cmp r5, #0 @ cpu id == 0
beq normal_setup
@ cpu id > 0, stop or wait
#ifdef RT_SMP_AUTO_BOOT
ldr r0, =secondary_cpu_entry
mov r1, #0
str r1, [r0] /* clean secondary_cpu_entry */
#endif /* RT_SMP_AUTO_BOOT */
secondary_loop:
@ cpu core 1 goes into sleep until core 0 wakeup it
wfe
#ifdef RT_SMP_AUTO_BOOT
ldr r1, =secondary_cpu_entry
ldr r0, [r1]
cmp r0, #0
blxne r0 /* if(secondary_cpu_entry) secondary_cpu_entry(); */
#endif /* RT_SMP_AUTO_BOOT */
b secondary_loop
normal_setup:
/* 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 */
#ifdef RT_USING_SMP
mrc p15, 0, r1, c1, c0, 1
mov r0, #(1<<6)
orr r1, r0
mcr p15, 0, r1, c1, c0, 1 //enable smp
#endif
/* enable branch prediction */
mrc p15, 0, r0, c1, c0, 0
orr r0, r0, #(1<<11)
mcr p15, 0, r0, c1, c0, 0
/* initialize the mmu table and enable mmu */
ldr r0, =platform_mem_desc
ldr r1, =platform_mem_desc_size
ldr r1, [r1]
bl rt_hw_init_mmu_table
bl rt_hw_mmu_init
/* 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
@ Set the startup stack for svc
mov sp, r0
sub r0, r0, #SVC_Stack_Size
@ 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, #RT_FIQ_STACK_PGSZ
@ Enter IRQ Mode and set its Stack Pointer
msr cpsr_c, #Mode_IRQ|I_Bit|F_Bit
mov sp, r0
sub r0, r0, #RT_IRQ_STACK_PGSZ
/* come back to SVC mode */
msr cpsr_c, #Mode_SVC|I_Bit|F_Bit
bx lr
/* exception handlers: undef, swi, padt, dabt, resv, irq, fiq */
.section .text.isr, "ax"
.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
.align 5
.globl vector_irq
vector_irq:
#ifdef RT_USING_SMP
clrex
stmfd sp!, {r0, r1}
cps #Mode_SVC
mov r0, sp /* svc_sp */
mov r1, lr /* svc_lr */
cps #Mode_IRQ
sub lr, #4
stmfd r0!, {r1, lr} /* svc_lr, svc_pc */
stmfd r0!, {r2 - r12}
ldmfd sp!, {r1, r2} /* original r0, r1 */
stmfd r0!, {r1 - r2}
mrs r1, spsr /* original mode */
stmfd r0!, {r1}
#ifdef RT_USING_LWP
stmfd r0, {r13, r14}^ /* usr_sp, usr_lr */
sub r0, #8
#endif
#ifdef RT_USING_FPU
/* fpu context */
vmrs r6, fpexc
tst r6, #(1<<30)
beq 1f
vstmdb r0!, {d0-d15}
vstmdb r0!, {d16-d31}
vmrs r5, fpscr
stmfd r0!, {r5}
1:
stmfd r0!, {r6}
#endif
/* now irq stack is clean */
/* r0 is task svc_sp */
/* backup r0 -> r8 */
mov r8, r0
bl rt_interrupt_enter
bl rt_hw_trap_irq
bl rt_interrupt_leave
cps #Mode_SVC
mov sp, r8
mov r0, r8
bl rt_scheduler_do_irq_switch
b rt_hw_context_switch_exit
#else
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]
mov r1, sp @ r1 point to {r0-r3} in stack
add sp, sp, #4*4
ldmfd sp!, {r4-r12,lr}@ reload saved registers
mrs r0, spsr @ get cpsr of interrupt thread
sub r2, lr, #4 @ save old task's pc to r2
@ Switch to SVC mode with no interrupt. If the usr mode guest is
@ interrupted, this will just switch to the stack of kernel space.
@ save the registers in kernel space won't trigger data abort.
msr cpsr_c, #I_Bit|F_Bit|Mode_SVC
stmfd sp!, {r2} @ push old task's pc
stmfd sp!, {r4-r12,lr}@ push old task's lr,r12-r4
ldmfd r1, {r1-r4} @ restore r0-r3 of the interrupt thread
stmfd sp!, {r1-r4} @ push old task's r0-r3
stmfd sp!, {r0} @ push old task's cpsr
#ifdef RT_USING_LWP
stmfd sp, {r13, r14}^ @push usr_sp, usr_lr
sub sp, #8
#endif
#ifdef RT_USING_FPU
/* fpu context */
vmrs r6, fpexc
tst r6, #(1<<30)
beq 1f
vstmdb sp!, {d0-d15}
vstmdb sp!, {d16-d31}
vmrs r5, fpscr
stmfd sp!, {r5}
1:
stmfd sp!, {r6}
#endif
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
#ifdef RT_USING_FPU
/* fpu context */
ldmfd sp!, {r6}
vmsr fpexc, r6
tst r6, #(1<<30)
beq 1f
ldmfd sp!, {r5}
vmsr fpscr, r5
vldmia sp!, {d16-d31}
vldmia sp!, {d0-d15}
1:
#endif
#ifdef RT_USING_LWP
ldmfd sp, {r13, r14}^ @pop usr_sp, usr_lr
add sp, #8
#endif
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
#endif
.macro push_svc_reg
sub sp, sp, #17 * 4 @/* Sizeof(struct rt_hw_exp_stack) */
stmia sp, {r0 - r12} @/* Calling r0-r12 */
mov r0, sp
mrs r6, spsr @/* Save CPSR */
str lr, [r0, #15*4] @/* Push PC */
str r6, [r0, #16*4] @/* Push CPSR */
cps #Mode_SVC
str sp, [r0, #13*4] @/* Save calling SP */
str lr, [r0, #14*4] @/* Save calling PC */
.endm
.align 5
.weak vector_swi
vector_swi:
push_svc_reg
bl rt_hw_trap_swi
b .
.align 5
.globl vector_undef
vector_undef:
push_svc_reg
cps #Mode_UND
bl rt_hw_trap_undef
#ifdef RT_USING_FPU
ldr lr, [sp, #15*4]
ldmia sp, {r0 - r12}
add sp, sp, #17 * 4
movs pc, lr
#endif
b .
.align 5
.globl vector_pabt
vector_pabt:
push_svc_reg
bl rt_hw_trap_pabt
b .
.align 5
.globl vector_dabt
vector_dabt:
push_svc_reg
bl rt_hw_trap_dabt
b .
.align 5
.globl vector_resv
vector_resv:
push_svc_reg
bl rt_hw_trap_resv
b .
#ifdef RT_USING_SMP
.global secondary_cpu_start
secondary_cpu_start:
#ifdef RT_USING_FPU
mov r4, #0xfffffff
mcr p15, 0, r4, c1, c0, 2
#endif
mrc p15, 0, r1, c1, c0, 1
mov r0, #(1<<6)
orr r1, r0
mcr p15, 0, r1, c1, c0, 1 //enable smp
mrc p15, 0, r0, c1, c0, 0
bic r0, #(1<<13)
mcr p15, 0, r0, c1, c0, 0
/* enable branch prediction */
mrc p15, 0, r0, c1, c0, 0
orr r0, r0, #(1<<11)
mcr p15, 0, r0, c1, c0, 0
@ get cpu id, and subtract the offset from the stacks base address
bl rt_hw_cpu_id
sub r5, r0, #1
ldr r0, =SUB_ISR_Stack_Size
mul r0, r0, r5 @r0 = SUB_ISR_Stack_Size * (cpuid - 1)
ldr r1, =sub_stack_top
sub r0, r1, r0 @r0 = sub_stack_top - (SUB_ISR_Stack_Size * (cpuid - 1))
cps #Mode_SVC
mov sp, r0
sub r0, r0, #SUB_SVC_Stack_Size
cps #Mode_UND
mov sp, r0
sub r0, r0, #SUB_UND_Stack_Size
cps #Mode_ABT
mov sp, r0
sub r0, r0, #SUB_ABT_Stack_Size
cps #Mode_FIQ
mov sp, r0
sub r0, r0, #SUB_RT_FIQ_STACK_PGSZ
cps #Mode_IRQ
mov sp, r0
sub r0, r0, #SUB_RT_IRQ_STACK_PGSZ
cps #Mode_SVC
/* initialize the mmu table and enable mmu */
bl rt_hw_mmu_init
b secondary_cpu_c_start
.bss
.align 2 //align to 2~2=4
sub_stack_start:
.space (SUB_ISR_Stack_Size * (RT_CPUS_NR-1))
sub_stack_top:
#endif
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