android源码中的gdb和gdbserver工具
gdbserver(GNU gdbserver (GDB) 7.6)
prebuilts/misc/android-arm/gdbserver/gdbserver
gdb(GNU gdb (GDB) 7.6)
prebuilts/gcc/linux-x86/arm/arm-eabi-4.8/bin/arm-eabi-gdb
应用调试(使用ADB转发端口连接)
在target上准备被调试程序
在开发板上启动gdbserver监听已经运行的程序的pid(比如911)
gdbserver :1234 --attach 911
或者是手动执行该被调试程序
gdbserver :1234 app_need_to_be_debug
在host上设置连接方法
启动gdb
./prebuilts/gcc/linux-x86/arm/arm-eabi-4.8/bin/arm-eabi-gdb -tui
host TCP端口4321转发到remote TCP端口1234,也可以在未启动gdb前配置好
(gdb) shell adb forward tcp:4321 tcp:1234
连接远程target
(gdb) target remote localhost:4321
库文件绝对路径
set solib-absolute-prefix /android_src/out/target/product/rk3288/symbols
库文件相对路径
set solib-search-path /android_src/out/target/product/rk3288/symbols/system/lib
加载调试二进制文件(io)对应源码目录(external/io)
(gdb) file /android_src/out/target/product/rk3288/symbols/system/xbin/io
调试过程中细节问题
执行continue后提示如下时说明程序没有跑起来
(gdb) c
The program is not being run.
此时需要在target上将程序跑起来
gdbserver :1234 app_need_to_be_debug
在host端再次连接target
(gdb) target remote localhost:4321
打断点时出现如下错误(程序的内存还没映射成功)
(gdb) b foo
Cannot access memory at address 0xe8a
此时需要先让程序跑起来一下
(gdb) c
之后再次执行打断点操作即可
(gdb) b foo
另外可以将在gdb里这些操作配置写在一个文件中(比如gdb_config),在gdb里直接source即可
(gdb) source gdb_config
gdb_config内容如下供参考
layout split
shell adb forward tcp:4321 tcp:1234
target remote localhost:4321
set solib-absolute-prefix /path/to/android_src/out/target/product/rk3288/symbols
set solib-search-path /path/to/android_src/out/target/product/rk3288/symbols/system/lib
file /path/to/android_src/out/target/product/rk3288/symbols/system/xbin/gout1
实例1(android上动态库bluetooth.default.so调试)
错误日志如下(size > GKI_MAX_BUF_SIZE)
--------- beginning of crash
01-14 04:19:10.896 1404 1471 F libc : system/bt/hci/src/buffer_allocator.c:26: buffer_alloc: assertion "size <= GKI_MAX_BUF_SIZE" failed
01-14 04:19:10.897 1404 1471 F libc : Fatal signal 6 (SIGABRT), code -6 in tid 1471 (bluedroid wake/)
01-14 04:19:10.898 234 234 F DEBUG : *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
01-14 04:19:10.899 234 234 F DEBUG : Revision: '0'
01-14 04:19:10.899 234 234 F DEBUG : ABI: 'arm'
01-14 04:19:10.899 234 234 F DEBUG : pid: 1404, tid: 1471, name: bluedroid wake/ >>> com.android.bluetooth <<<
01-14 04:19:10.899 234 234 F DEBUG : signal 6 (SIGABRT), code -6 (SI_TKILL), fault addr --------
01-14 04:19:10.915 234 234 F DEBUG : Abort message: 'system/bt/hci/src/buffer_allocator.c:26: buffer_alloc: assertion "size <= GKI_MAX_BUF_SIZE" failed'
01-14 04:19:10.915 234 234 F DEBUG : r0 00000000 r1 000005bf r2 00000006 r3 a0c16978
01-14 04:19:10.915 234 234 F DEBUG : r4 a0c16980 r5 a0c16930 r6 00000000 r7 0000010c
01-14 04:19:10.915 234 234 F DEBUG : r8 0000930f r9 0000930f sl a15e8f48 fp a15e8ecc
01-14 04:19:10.915 234 234 F DEBUG : ip 00000006 sp a0c16390 lr b6ca7ec9 pc b6caa2b8 cpsr 400f0010
01-14 04:19:10.926 234 234 F DEBUG :
01-14 04:19:10.926 234 234 F DEBUG : backtrace:
01-14 04:19:10.926 234 234 F DEBUG :
01-14 04:19:10.926 234 234 F DEBUG :
01-14 04:19:10.926 234 234 F DEBUG :
01-14 04:19:10.927 234 234 F DEBUG :
01-14 04:19:10.927 234 234 F DEBUG :
01-14 04:19:10.927 234 234 F DEBUG :
01-14 04:19:10.927 234 234 F DEBUG :
01-14 04:19:10.927 234 234 F DEBUG :
01-14 04:19:10.927 234 234 F DEBUG :
01-14 04:19:10.927 234 234 F DEBUG :
01-14 04:19:10.927 234 234 F DEBUG :
01-14 04:19:10.927 234 234 F DEBUG :
01-14 04:19:10.927 234 234 F DEBUG :
01-14 04:19:10.927 234 234 F DEBUG :
01-14 04:19:10.927 234 234 F DEBUG :
01-14 04:19:11.343 234 234 F DEBUG :
01-14 04:19:11.343 234 234 F DEBUG : Tombstone written to: /data/tombstones/tombstone_01
欲调试的库bluetooth.default.so被进程com.android.bluetooth使用
所以可以将gdbserver附加到该进程即可
在android设备上执行(gdb attach到blue的进程上)
gdbserver :1234 --attach `ps | grep bluetooth | busybox1.11 awk '{print $2}'`
gdb配置文件内容如下(ble_cfg)
layout split
shell adb forward tcp:4321 tcp:1234
target remote localhost:4321
set solib-absolute-prefix /home/zeroway/android6.0/out/target/product/rk3288/symbols
set solib-search-path /home/zeroway/android6.0/out/target/product/rk3288/symbols/system/lib
在主机上启动gdb(进入后source ble_cfg) 并在system/bt/hci/src/buffer_allocator.c中函数(buffer_alloc)打断点
./prebuilts/gcc/linux-x86/arm/arm-eabi-4.8/bin/arm-eabi-gdb
(gdb) source ble_cfg
(gdb) b buffer_alloc
(gdb) continue
设置条件断点
(gdb) b buffer_alloc if size > 4096
在android设备上操作蓝牙(比如刷新操作)之后就能停在buffer_alloc函数
通过串口调试内核
配置内核
配置如下选项
CONFIG_KGDB=y
CONFIG_CONSOLE_POLL=y
CONFIG_HAVE_ARCH_KGDB=y
CONFIG_KGDB_SERIAL_CONSOLE=y
CONFIG_KGDB_KDB=y
CONFIG_KDB_CONTINUE_CATASTROPHIC=0
TARGET上打开KGDB调试开关
关闭watchdog
echo 0 > /proc/sys/kernel/watchdog
设置kgdb over console(其中ttyFIQ0是调试串口)
echo 'ttyFIQ0,115200' > /sys/module/kgdboc/parameters/kgdboc
开启kgdb
echo g > /proc/sysrq-trigger
HOST上调试
在android上使用SDK里的gdb工具
prebuilts/gcc/linux-x86/arm/arm-eabi-4.8/bin/arm-eabi-gdb -tui
通过串口连接到TARGET(由于使用的是调试串口,所以需要关掉调试串口)
(gdb) set remotebaud 115200
(gdb) target remote /dev/ttyUSB0
加载未压缩的内核
file vmlinux
在使用GDB单步调试内核过程中会遇到由于代码经过编译器优化后无法显示变量值问题
value optimized out
解决方法一般是使用-O0来编译内核
解决方法二是针对某个函数关闭优化
void __attribute__((optimize("O0"))) foo(unsigned char data)
{
}
解决方法三是针对某个文件(模块XXX)不做优化处理
CFLAGS_XXX.o = -O0
比如需要调试composite.c和f_acm.c这两个模块 修改(kernel/drivers/usb/gadget/Makefile)
libcomposite-y += composite.o functions.o configfs.o
CFLAGS_composite.o = -O0
usb_f_acm-y := f_acm.o
CFLAGS_f_acm.o = -O0
使用GDB的一些便利之处
在看代码过程中经常遇到下面这样的代码
value = usb_ep_queue(cdev->gadget->ep0, req, GFP_ATOMIC);
static inline int usb_ep_queue(struct usb_ep *ep,
struct usb_request *req, gfp_t gfp_flags)
{
return ep->ops->queue(ep, req, gfp_flags);
}
需要找到这里调用的queue是哪里的代码,往往需要花上一段时间
这里可以利用gdb来查看(dwc_otg_pcd_ep_ops)
(gdb) p *cdev->gadget->ep0
$8 = {
driver_data = 0xc48c6e80,
name = 0xc0c53644 "ep0",
ops = 0xc1a40d24 <dwc_otg_pcd_ep_ops>,
ep_list = {
next = 0xdce41128,
prev = 0xdce41128
},
maxpacket = 64,
max_streams = 0,
mult = 0,
maxburst = 0,
address = 0 '\000',
desc = 0x0 <__vectors_start>,
comp_desc = 0x0 <__vectors_start>
}
原作者：54shady
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