使用 Qemu 调试 LoongArch 应用程序
1.编译 Qemu
OS:Ubuntu 22.04
下载Qemu源码
git clone --depth=1 https://gitlab.com/qemu-project/qemu.git
编译
cd qemu
mkdir build
cd build
../configure --target-list=loongarch64-linux-user,loongarch64-softmmu --prefix=`pwd`/__install
make && make install
测试
$ cd __install/
$ ls
bin include libexec share var
$ cd bin/
$ ls
elf2dmp hello qemu-edid qemu-ga qemu-img qemu-io qemu-keymap qemu-loongarch64 qemu-nbd qemu-pr-helper qemu-storage-daemon qemu-system-loongarch64 qemu-vmsr-helper sum
$ ./qemu-loongarch64 --version
qemu-loongarch64 version 10.0.50
Copyright (c) 2003-2025 Fabrice Bellard and the QEMU Project developers
2.应用程序调试
交叉工具链
gcc13: https://gitee.com/open-loongarch/cross-toolchain/tree/master/gcc-13
gcc14: https://github.com/loongson/build-tools/releases/tag/2025.02.21
本案例使用是的gcc13。
2.1 汇编程序
2.1.1 源码
$ cat sum.s .section .text.globl _start_start:addi.w $t0, $zero, 0 # $t0 = 0 (累加器)addi.w $t1, $zero, 1 # $t1 = 1 (计数器)loop:add.w $t0, $t0, $t1 # $t0 = $t0 + $t1addi.w $t1, $t1, 1 # $t1 = $t1 + 1addi.w $t2, $zero, 6 # $t2 = 6 (终止值)slt $t3, $t1, $t2 # $t3 = ($t1 < $t2) ? 1 : 0bnez $t3, loop # 若 $t3 != 0，跳转到 loop# 终止程序（LoongArch 系统调用）addi.w $a7, $zero, 93 # exit 系统调用号 = 93addi.w $a0, $zero, 0 # 退出码 = 0syscall 0 # 调用内核
2.1.2 编译
$ loongarch64-linux-gcc -v
Using built-in specs.
COLLECT_GCC=/opt/loongarch64-linux-gnu-gcc13.3/bin/loongarch64-linux-gcc.br_real
COLLECT_LTO_WRAPPER=/opt/loongarch64-linux-gnu-gcc13.3/bin/../libexec/gcc/loongarch64-loongson-linux-gnu/13.3.0/lto-wrapper
Target: loongarch64-loongson-linux-gnu
Configured with: ./configure --prefix=/home/loongson/data1/work-tao/buildroot/buildroot-2024.08/output/host --sysconfdir=/home/loongson/data1/work-tao/buildroot/buildroot-2024.08/output/host/etc --enable-static --target=loongarch64-loongson-linux-gnu --with-sysroot=/home/loongson/data1/work-tao/buildroot/buildroot-2024.08/output/host/loongarch64-loongson-linux-gnu/sysroot --enable-__cxa_atexit --with-gnu-ld --disable-libssp --disable-multilib --disable-decimal-float --enable-plugins --enable-lto --with-gmp=/home/loongson/data1/work-tao/buildroot/buildroot-2024.08/output/host --with-mpc=/home/loongson/data1/work-tao/buildroot/buildroot-2024.08/output/host --with-mpfr=/home/loongson/data1/work-tao/buildroot/buildroot-2024.08/output/host --with-pkgversion='Buildroot -ge7e368b6-dirty' --with-bugurl=https://gitlab.com/buildroot.org/buildroot/-/issues --without-zstd --disable-libquadmath --disable-libquadmath-support --enable-tls --enable-threads --without-isl --without-cloog --with-abi=lp64d --enable-languages=c,c++ --with-build-time-tools=/home/loongson/data1/work-tao/buildroot/buildroot-2024.08/output/host/loongarch64-loongson-linux-gnu/bin --enable-shared --disable-libgomp
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 13.3.0 (Buildroot -ge7e368b6-dirty)$ loongarch64-linux-gcc -g sum.s -o sum -nostdlib
sum.s: Assembler messages:
sum.s: Warning: end of file in comment; newline inserted$ file sum
sum: ELF 64-bit LSB executable, LoongArch, version 1 (SYSV), statically linked, with debug_info, not stripped
2.1.3 调试
通过qemu-loongarch64 运行应用程序，并指定gdb 的端口号为 1234，同时指定库的路径，如果程序是静态编译的则不需要。
$ ./qemu-loongarch64 -L /opt/loongarch64-linux-gnu-gcc13.3/loongarch64-loongson-linux-gnu/sysroot/ -g 1234 ./sum
运行loongarch64-linux-gdb 进行在线debug
$ loongarch64-linux-gdb
GNU gdb (GDB) 14.2
Copyright (C) 2023 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "--host=x86_64-pc-linux-gnu --target=loongarch64-loongson-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<https://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:<http://www.gnu.org/software/gdb/documentation/>.For help, type "help".
Type "apropos word" to search for commands related to "word".
(gdb) target remote :1234
Remote debugging using :1234
Reading /home/vm/work/qemu/qemu/build/__install/bin/sum from remote target...
warning: File transfers from remote targets can be slow. Use "set sysroot" to access files locally instead.
Reading /home/vm/work/qemu/qemu/build/__install/bin/sum from remote target...
Reading symbols from target:/home/vm/work/qemu/qemu/build/__install/bin/sum...
_start () at sum.s:5
5 addi.w $t0, $zero, 0 # $t0 = 0 (累加器)
(gdb) b _start
Breakpoint 1 at 0x120000078: file sum.s, line 5.
(gdb) n
_start () at sum.s:6
6 addi.w $t1, $zero, 1 # $t1 = 1 (计数器)
(gdb)
loop () at sum.s:9
9 add.w $t0, $t0, $t1 # $t0 = $t0 + $t1
(gdb)
loop () at sum.s:10
10 addi.w $t1, $t1, 1 # $t1 = $t1 + 1
(gdb)
loop () at sum.s:11
11 addi.w $t2, $zero, 6 # $t2 = 6 (终止值)
(gdb)
loop () at sum.s:13
13 slt $t3, $t1, $t2 # $t3 = ($t1 < $t2) ? 1 : 0
(gdb) i r
r0 0x0 0
r1 0x0 0x0
r2 0x0 0x0
r3 0x76e842351000 0x76e842351000
r4 0x0 0
r5 0x0 0
r6 0x0 0
r7 0x0 0
r8 0x0 0
r9 0x0 0
r10 0x0 0
r11 0x0 0
r12 0x1 1
r13 0x2 2
r14 0x6 6
r15 0x0 0
r16 0x0 0
r17 0x0 0
r18 0x0 0
r19 0x0 0
r20 0x0 0
r21 0x0 0
r22 0x0 0x0
r23 0x0 0
r24 0x0 0
r25 0x0 0
r26 0x0 0
r27 0x0 0
r28 0x0 0
r29 0x0 0
r30 0x0 0
r31 0x0 0
orig_a0 0x0 0
pc 0x12000008c 0x12000008c <loop+12>
badv 0x0 0x0
(gdb)2.2 C 程序
2.2.1 源码
$ cat hello.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>int foo(int a, int b)
{int c = 0;c = a + b;return c;
}int main(int argc, char *argv[])
{int a = 10;int b = 20;int c = 0;c = foo(a, b);printf("%d + %d = %d\n", a, b);return 0;
}2.2.2 编译
$ loongarch64-linux-gcc -g hello.c -o hello
2.2.3 调试
通过qemu-loongarch64 运行应用程序，并指定gdb 的端口号为 1234，同时指定库的路径，如果程序是静态编译的则不需要。
$ ./qemu-loongarch64 -L /opt/loongarch64-linux-gnu-gcc13.3/loongarch64-loongson-linux-gnu/sysroot/ -g 1234 ./hello
运行loongarch64-linux-gdb 进行在线debug
$ loongarch64-linux-gdb
GNU gdb (GDB) 14.2
Copyright (C) 2023 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "--host=x86_64-pc-linux-gnu --target=loongarch64-loongson-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<https://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:<http://www.gnu.org/software/gdb/documentation/>.For help, type "help".
Type "apropos word" to search for commands related to "word".
(gdb) target remote :1234
Remote debugging using :1234
Reading /home/vm/work/qemu/qemu/build/__install/bin/hello from remote target...
warning: File transfers from remote targets can be slow. Use "set sysroot" to access files locally instead.
Reading /home/vm/work/qemu/qemu/build/__install/bin/hello from remote target...
Reading symbols from target:/home/vm/work/qemu/qemu/build/__install/bin/hello...
Reading /lib64/ld-linux-loongarch-lp64d.so.1 from remote target...
Reading /lib64/ld-linux-loongarch-lp64d.so.1 from remote target...
Reading symbols from target:/lib64/ld-linux-loongarch-lp64d.so.1...
(No debugging symbols found in target:/lib64/ld-linux-loongarch-lp64d.so.1)
0x000070f166e68754 in _start () from target:/lib64/ld-linux-loongarch-lp64d.so.1
(gdb) b main
Breakpoint 1 at 0x120000648: file hello.c, line 15.
(gdb) c
Continuing.
Reading /lib64/libc.so.6 from remote target...Breakpoint 1, main (argc=1, argv=0x70f166016008) at hello.c:15
15 int a = 10;
(gdb) n
16 int b = 20;
(gdb)
17 int c = 0;
(gdb)
19 c = foo(a, b);
(gdb) s
foo (a=10, b=20) at hello.c:7
7 int c = 0;
(gdb)
9 c = a + b;
(gdb)
10 return c;
(gdb)
11 }
(gdb)
main (argc=1, argv=0x70f166016008) at hello.c:20
20 printf("%d + %d = %d\n", a, b);
(gdb) p c
$1 = 30
(gdb)