gdb调试kernel的时候, 如果设置通用函数断点, 比如vfs_read, 就会遇到一堆撞到断点的地方, 比如tty输入一个字符, 就是vfs_read, 没办法调试具体的某一个进程
一种办法就是条件断点, 其实不是很好用, 比如用pid, 但是有时候这个进程还没启动, 比如task的comm来判定, 但是kernel中是不支持strcmp来判断字符串是否相等, 因为需要跑函数
gdb 7.5对此问题做了增强, gdb自己去比较字符串, 而不需要机器去跑代码
https://sourceware.org/gdb/current/onlinedocs/gdb/Convenience-Funs.html#Convenience-Funs
b do_fault if $_streq($lx_current()->comm, "a.out")还可以对调用者来做条件断点, 比如a->c, b->c, 断点只停在b调用c的地方
$_caller_is(name[, number_of_frames])
Returns one if the calling function’s name is equal to name. Otherwise it returns zero.
If the optional argument number_of_frames is provided, it is the number of frames up in the stack to look. The default is 1.
Example:
(gdb) backtrace
#0 bottom_func ()
at testsuite/gdb.python/py-caller-is.c:21
#1 0x00000000004005a0 in middle_func ()
at testsuite/gdb.python/py-caller-is.c:27
#2 0x00000000004005ab in top_func ()
at testsuite/gdb.python/py-caller-is.c:33
#3 0x00000000004005b6 in main ()
at testsuite/gdb.python/py-caller-is.c:39
(gdb) print $_caller_is ("middle_func")
$1 = 1
(gdb) print $_caller_is ("top_func", 2)
$1 = 1
