arm 交叉编译 thumb 与 arm 指令的方法

• 本文实现了在 x86 的 ubuntu 的机器上，使用 arm-linux-gnueabihf-gcc 交叉编译链工具，编译出在 arm 开发板上可以运行的 thumb 指令集的可执行文件。后续会使用 vscode 使用网络进行远程调试。

1. 编译器 arm-linux-gnueabihf-gcc

# arm-linux-gnueabihf-gcc -v
Using built-in specs.
COLLECT_GCC=arm-linux-gnueabihf-gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc-cross/arm-linux-gnueabihf/11/lto-wrapper
Target: arm-linux-gnueabihf
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 11.4.0-1ubuntu1~22.04' --with-bugurl=file:///usr/share/doc/gcc-11/README.Bugs --enable-languages=c,ada,c++,go,d,fortran,objc,obj-c++,m2 --prefix=/usr --with-gcc-major-version-only --program-suffix=-11 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-libitm --disable-libquadmath --disable-libquadmath-support --enable-plugin --enable-default-pie --with-system-zlib --enable-libphobos-checking=release --without-target-system-zlib --enable-multiarch --disable-sjlj-exceptions --with-arch=armv7-a+fp --with-float=hard --with-mode=thumb --disable-werror --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=arm-linux-gnueabihf --program-prefix=arm-linux-gnueabihf- --includedir=/usr/arm-linux-gnueabihf/include --with-build-config=bootstrap-lto-lean --enable-link-serialization=2
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 11.4.0 (Ubuntu 11.4.0-1ubuntu1~22.04) 

ubuntu 中安装方法 sudo apt-get install binutils-arm-linux-gnueabi gcc-arm-linux-gnuabihf

2. 代码中实现

使用 __attribute__((target("thumb"))) void thumb_ins(void); 指定函数编译为 thumb 指令

//完整的 main.c 的示例
#include <stdio.h>__attribute__((target("thumb"))) void thumb_ins(void);
void thumb_ins(void) {int ia = 0;int ib = 0;int ic = 0;while (1) {ia = 0;ib = 0;ic = 0xab;asm volatile ("mov r0, #1");asm volatile ("mov r4, #0");asm volatile ("cmp r4, #0");asm volatile ("itte  eq");asm volatile ("moveq r1, #55");asm volatile ("moveq r2, #66");asm volatile ("movne r2, #77");asm volatile ("mov %0, r1" : "=r" (ia));asm volatile ("mov %0, r2" : "=r" (ib));asm volatile ("mov %0, r0" : "=r" (ic));if ((ia != 55) || (ib != 66)) {printf("error!!!");printf(" ia %d ib %d  %d\r\n", ia, ib, ic);}}
}int main(void)
{printf("I run!!! %s %s\r\n", __TIME__, __DATE__);while (1) {thumb_ins();}return 0;
}

3. 编译方法

• 编译指令 arm-linux-gnueabihf-gcc -g -static -mthumb-interwork -mthumb main.c
  
  参数解释：
  
  -g 添加调试信息
  
  -static 使用静态链接的方式
  
  -mthumb 使用 thumb 指令集
  
  -mthumb-interwork 支持 arm 与 thumb 混合
  

• 反汇编查看是否正确 arm-linux-gnueabihf-objdump -S a.out > a.asm

__attribute__((target("thumb"))) void thumb_ins(void);
void thumb_ins(void) {10438:	b580      	push	{r7, lr}1043a:	b084      	sub	sp, #161043c:	af00      	add	r7, sp, #0int ia = 0;1043e:	2300      	movs	r3, #010440:	607b      	str	r3, [r7, #4]int ib = 0;10442:	2300      	movs	r3, #010444:	60bb      	str	r3, [r7, #8]int ic = 0;10446:	2300      	movs	r3, #010448:	60fb      	str	r3, [r7, #12]while (1) {ia = 0;1044a:	2300      	movs	r3, #01044c:	607b      	str	r3, [r7, #4]ib = 0;1044e:	2300      	movs	r3, #010450:	60bb      	str	r3, [r7, #8]ic = 0xab;10452:	23ab      	movs	r3, #171	; 0xab10454:	60fb      	str	r3, [r7, #12]asm volatile ("mov r0, #1");10456:	f04f 0001 	mov.w	r0, #1asm volatile ("mov r4, #0");1045a:	f04f 0400 	mov.w	r4, #0asm volatile ("cmp r4, #0");1045e:	2c00      	cmp	r4, #0asm volatile ("itte  eq");10460:	bf06      	itte	eqasm volatile ("moveq r1, #55");10462:	2137      	moveq	r1, #55	; 0x37asm volatile ("moveq r2, #66");10464:	2242      	moveq	r2, #66	; 0x42asm volatile ("movne r2, #77");10466:	224d      	movne	r2, #77	; 0x4dasm volatile ("mov %0, r1" : "=r" (ia));10468:	460b      	mov	r3, r11046a:	607b      	str	r3, [r7, #4]asm volatile ("mov %0, r2" : "=r" (ib));1046c:	4613      	mov	r3, r21046e:	60bb      	str	r3, [r7, #8]asm volatile ("mov %0, r0" : "=r" (ic));10470:	4603      	mov	r3, r010472:	60fb      	str	r3, [r7, #12]if ((ia != 55) || (ib != 66)) {10474:	687b      	ldr	r3, [r7, #4]10476:	2b37      	cmp	r3, #55	; 0x3710478:	d102      	bne.n	10480 <thumb_ins+0x48>1047a:	68bb      	ldr	r3, [r7, #8]1047c:	2b42      	cmp	r3, #66	; 0x421047e:	d0e4      	beq.n	1044a <thumb_ins+0x12>printf("error!!!");10480:	4b06      	ldr	r3, [pc, #24]	; (1049c <thumb_ins+0x64>)10482:	447b      	add	r3, pc10484:	4618      	mov	r0, r310486:	f004 fb67 	bl	14b58 <_IO_printf>printf(" ia %d ib %d  %d\r\n", ia, ib, ic);1048a:	68fb      	ldr	r3, [r7, #12]1048c:	68ba      	ldr	r2, [r7, #8]1048e:	6879      	ldr	r1, [r7, #4]10490:	4803      	ldr	r0, [pc, #12]	; (104a0 <thumb_ins+0x68>)10492:	4478      	add	r0, pc10494:	f004 fb60 	bl	14b58 <_IO_printf>ia = 0;10498:	e7d7      	b.n	1044a <thumb_ins+0x12>1049a:	bf00      	nop1049c:	0003f1be 	.word	0x0003f1be104a0:	0003f1ba 	.word	0x0003f1ba000104a4 <main>:}
}

最后将 a.out 放入目标板卡使用 chmod +x 添加执行权限，即可运行。