GDB显示线程信息的时候为什么线程函数全部显示为问号

[tmfjtft]

通过GDB server和 arm-linux-gdb调试程序.当用 info threads命令显示线程信息时,得到如下,函数全是问号.

(gdb) info threads
[New Thread 1523]
[New Thread 1524]
[New Thread 1525]
[New Thread 1526]
[New Thread 1527]
[New Thread 1528]
[New Thread 1529]
Id Target Id Frame
8 Thread 1529 0x40120cc4 in ?? ()
7 Thread 1528 0x40120cc4 in ?? ()
6 Thread 1527 0x40120cc4 in ?? ()
5 Thread 1526 0x40120cc4 in ?? ()
4 Thread 1525 0x40120cc4 in ?? ()
3 Thread 1524 0x40120cc4 in ?? ()
2 Thread 1523 0x40120cc4 in ?? ()
* 1 Thread 1512 0x4003b384 in ?? ()
(gdb)

打印堆栈的时候: inc_can1_run ()为线程函数.
(gdb) bt
#0 can1_get_send_cmd (pT_send_cmd=0x484cc <g_t_can1_send_cmd_buff>,
pPolling_round=0x48340 <g_can1_sendPackNum>) at IncCan1Update.c:868
#1 0x00012fde in inc_can1_packet_send () at IncThreadCan1.c:113
#2 0x00013150 in inc_can1_run () at IncThreadCan1.c:245
#3 0x40033ed2 in ?? ()
#4 0x40033ed2 in ?? ()
Backtrace stopped: previous frame identical to this frame (corrupt stack?)
(gdb)