dump_stack使用

我们在调试内核时可以用printk打印信息。但有时我们不知道一个函数或者一个模块到底在哪里出了问题。这时我们可以用dump_stack打印信息，查看函数调用关系，找到问题的根源。使用实例：

hello.c

#include <linux/module.h>
#include <linux/init.h>
#include <linux/kprobes.h>
#include <asm/traps.h>

static int __init hello_init(void)
{
    printk(KERN_ALERT "dump_stack start\n");
    dump_stack();
    printk(KERN_ALERT "dump_stack over\n");
    return 0;
}

static void __exit hello_exit(void)
{
    printk(KERN_ALERT "test module\n");
}

module_init(hello_init);
module_exit(hello_exit);

Makefile

#hello_makefile
obj-m :=hello.o
KERNELDIR :=/lib/modules/$(shell uname -r)/build
PWD :=$(shell pwd)
all:
    make -C $(KERNELDIR) M=$(PWD) modules
    
.PHONY :clean
clean:
    rm -rf *.o *ko

然后make得到hello.ko
在运行insmod hello.ko把模块插入内核
运行dmesg

得到内核打印信息：

[384625.351387] Call Trace:
[384625.387169]  dump_stack+0x63/0x8b
[384625.387181]  ? 0xffffffffc03b8000
[384625.387184]  hello_init+0x15/0x1000 [hello]
[384625.389391]  do_one_initcall+0x55/0x1a6
[384625.389399]  ? 0xffffffffc03b8000
[384625.390037]  do_init_module+0x5f/0x209
[384625.390048]  load_module+0x1996/0x1da0
[384625.390052]  SYSC_finit_module+0xe5/0x120
[384625.390054]  ? SYSC_finit_module+0xe5/0x120
[384625.390056]  SyS_finit_module+0xe/0x10
[384625.390116]  entry_SYSCALL_64_fastpath+0x24/0xab
[384625.390120] RIP: 0033:0x7f3054b5a4d9
[384625.390120] RSP: 002b:00007ffd4af6b128 EFLAGS: 00000206 ORIG_RAX: 0000000000000139
[384625.390175] RAX: ffffffffffffffda RBX: 00007f3054e1db20 RCX: 00007f3054b5a4d9
[384625.390176] RDX: 0000000000000000 RSI: 0000555dcee5326b RDI: 0000000000000003
[384625.390176] RBP: 0000000000001011 R08: 0000000000000000 R09: 00007f3054e1fea0
[384625.390177] R10: 0000000000000003 R11: 0000000000000206 R12: 00007f3054e1db78
[384625.390178] R13: 00007f3054e1db78 R14: 000000000000270f R15: 00007f3054e1e1a8
[384625.390570] dump_stack over

调用顺序：entry_SYSCALL_64_fastpath -> SyS_finit_module ->  SYSC_finit_module ->  load_module -> do_init_module -> do_one_initcall ->  hello_init

更多信息参考：https://www.cnblogs.com/sky-heaven/p/6297675.html