00. 目录

01. 开发环境

• 开发板：Tiny4412SDK标准版 「Tiny4412 SDK 1506」
• 工具：「arm-linux-gcc-4.5.1」 「minicom」 「dnw」
• 平台：Ubuntu 20.04

02. 中断向量表

B1.8.1 Exception vectors and the exception base address

03. 中断向量表实现

vector.s文件内容如下

    .section .text.align 2.global vector_start
vector_start:b reset     @0x0b undef     @0x4b swi       @0x8b pabort    @0xCb dabort    @0x10nop         @0x14b irq       @0x18b firq      @0x1Creset:b resetundef:b undefswi:b swipabort:b pabortdabort:b dabortirq:b irqfirq:b firq.align 2.global vector_end
vector_end:nop

04. 设置Vectors bit

B6.1.86 SCTLR, System Control Register, PMSA

访问系统寄存器的方法

MRC p15, 0, <Rt>, c1, c0, 0 ; Read SCTLR into Rt
MCR p15, 0, <Rt>, c1, c0, 0 ; Write Rt to SCTLR

cp15.S增加如下函数

    .section .text.align 2.global set_vector_bit
set_vector_bit:mrc p15, 0, r0, c1, c0, 0orr r0, r0, #(1 << 13)mcr p15, 0, r0, c1, c0, 0mov pc, lr

05. 程序示例一

vector.s内容如下

    .section .rodata.align 2
.LC0:.string "system call open\n".LC1:.string "cpsr = %p\n"
.LC2:.string "system call num = %d\n".section .text.align 2.global vector_start
vector_start:b reset     @0x0b undef     @0x4b swi       @0x8b pabort    @0xCb dabort    @0x10nop         @0x14b irq       @0x18b firq      @0x1Creset:b resetundef:b undefswi:stmfd sp!, {r4, lr}ldr r0, .L0mov lr, pcldr pc, .L0 + 4ldmfd sp!, {r4, pc}pabort:b pabortdabort:b dabortirq:b irqfirq:b firq.L0:.word .LC0.word 0x43e11a2c @printf.word .LC1.word .LC2.align 2.global vector_end
vector_end:nop

start.S内容如下

    .section .text.align 2.global _start
_start:stmfd sp!, {r4, lr}bl mainldmfd sp!, {r4, pc}.section .text.align 2.global get_cpsr
get_cpsr:mrs r0, cpsrmov pc, lr.section .text.align 2.global system_call_open
system_call_open:stmfd sp!, {lr}swi #2ldmfd sp!, {pc}

test.c内容如下

#include <string.h>
#include <stdlib.h>
#include <adc.h>
#include <gpio.h>void (*udelay)(unsigned int) = (void*)0x43e26480;
int (*print)(const char *format, ...) = (void*)0x43e11a2c;extern unsigned int __bss_start;
extern unsigned int __bss_end;extern void vector_start();
extern void vector_end();//TTB的基地址
U32 *ttb = (void*)0x60000000;
U32 *ttb_c = (void*)0x61000000;int main(void)
{int i = 0;//0x40000000 ~ 0x80000000  1Gmemset((void*)&__bss_start, 0, (int)&__bss_end -(int)&__bss_start);print("main start\n");memset((void*)ttb, 0, 4096 * 4);ttb_l1_init(ttb);ttb_l1_mmap(ttb, 0xffff0000, 0x7fff0000);set_vector_bit();//设置TTB基地址set_ttb(ttb);//设置域访问的权限set_domain(0xffffffff);//使能MMUenable_mmu();//将中断向量表拷贝到0xffff0000地址处memcpy((void*)0xffff0000, (void*)vector_start, vector_end - vector_start);//产生软件中断system_call_open();print("main end\n");return 0;
}

执行结果

## Starting application at 0x50000000 ...
main start
system call open
main end
## Application terminated, rc = 0x0

06. 程序示例二

输出中断号和cpsr的值

vector.s内容如下

    .section .rodata.align 2
.LC0:.string "system call open\n"
.LC1:.string "cpsr = %p\n"
.LC2:.string "system call num = %d\n".section .text.align 2.global vector_start
vector_start:b reset     @0x0b undef     @0x4b swi       @0x8b pabort    @0xCb dabort    @0x10nop         @0x14b irq       @0x18b firq      @0x1Creset:b resetundef:b undefswi:stmfd sp!, {r4, lr}mov r4, lrldr r0, .L0mov lr, pcldr pc, .L0 + 4ldr r0, .L0 + 8mrs r1, cpsrmov lr, pcldr pc, .L0 + 4ldr r0, .L0 + 12sub r4, #4ldr r1, [r4]bic r1, r1, #0xff000000 @获取中断号mov lr, pcldr pc, .L0 + 4ldmfd sp!, {r4, lr}movs pc, lrpabort:b pabortdabort:b dabortirq:b irqfirq:b firq.L0:.word .LC0.word 0x43e11a2c @printf.word .LC1.word .LC2.align 2.global vector_end
vector_end:nop

test.c内容如下

#include <string.h>
#include <stdlib.h>
#include <adc.h>
#include <gpio.h>void (*udelay)(unsigned int) = (void*)0x43e26480;
int (*print)(const char *format, ...) = (void*)0x43e11a2c;extern unsigned int __bss_start;
extern unsigned int __bss_end;extern void vector_start();
extern void vector_end();//TTB的基地址
U32 *ttb = (void*)0x60000000;
U32 *ttb_c = (void*)0x61000000;int main(void)
{int i = 0;//0x40000000 ~ 0x80000000  1Gmemset((void*)&__bss_start, 0, (int)&__bss_end -(int)&__bss_start);print("main start\n");memset((void*)ttb, 0, 4096 * 4);ttb_l1_init(ttb);ttb_l1_mmap(ttb, 0xffff0000, 0x7fff0000);set_vector_bit();//设置TTB基地址set_ttb(ttb);//设置域访问的权限set_domain(0xffffffff);//使能MMUenable_mmu();//将中断向量表拷贝到0xffff0000地址处memcpy((void*)0xffff0000, (void*)vector_start, vector_end - vector_start);//产生软件中断system_call_open();print("main end\n");return 0;
}

执行结果

## Starting application at 0x50000000 ...
main start
system call open
cpsr = 600001d3
system call num = 2
main end
## Application terminated, rc = 0x0

07. 附录

6.1 Exynos 4412 SCP_Users Manual_Ver.0.10.00_Preliminary0.pdf

6.2 ARM® Architecture Reference Manual ARMv7-A and ARMv7-R edition