电脑bios debug 电脑BIOS DMI复制工具

dmidecode命令主要是通过DMI(Desktop Management Interface)获取主机的硬件信息，其输出的信息包括BIOS、系统、主板、处理器、内存、缓存等等。它是通过SMBIOS（System Management BIOS)来获取信息的。SMBIOS是主板或系统制造者以标准格式显示产品管理信息所需遵循的统一规范。

什么是DMI？

DMI (Desktop Management Interface, DMI)的主要组成部分是Management InformationFormat (MIF)数据库，这个数据库包括了所有有关电脑系统和配件的信息。

百度百科到的资料：

DMI是指Direct Media Interface(直接媒体接口）的缩写，DMI是Intel(英特尔)公司开发用于连接主板南北桥的总线，取代了以前的Hub-Link总线。DMI采用点对点的连接方式，时钟频率为100MHz，由于它是基于PCI-Express总线，同样采用8bit/10bit（有效位宽8bit）编码因此具有PCI-E总线的优势。

在4系列芯片组没有取消前端总线FSB时，DMI 是Intel(英特尔)公司开发用于北桥(G)MCH（Graphics & Memory controller hub）和南桥ICH10/ICH7之间的芯片连接总线。DMI实现了上行与下行双向数据传输率，单通道单向传输速率达到2.5GT/s，采用8bit/10bit编码，共计4条通道。这个高速接口集成了高级优先服务，允许并发通讯和真正的同步传输能力。它的基本功能对于软件是完全透明的，因此早期的软件也可以正常操作。

从5系列芯片组开始的新构架设计中，前端总线被取消，北桥芯片的功能被整合进CPU中。显卡采用了PCI-E ×16的通道直连CPU，当多卡交火时分为×8+×8（双卡）或×8+×4+×4（三卡）（具体分配方式要参考主板设计）。因为PCI-E2.0的应用，DMI升级到DMI2.0，单通道单向传输速率达到5GT/s。同时DMI2.0也不再用于南北桥芯片的连接，而是用于CPU和芯片组（原南桥芯片组）的连接。如下图所示，下图展示的是北桥集成到CPU后的情况：

所以，我们现在可以知道，为何dmidecode工具可以获取主板，内存等信息了，因为很多关于系统硬件的底层信息都是通过DMI通道获取的，我们看一下dmidecode工具的帮助信息：

dmidecode 工具会读取/sys/firmware/dmi/tables/smbios_entry_point文件。

czl@czl-Vostro-3268:~$ sudo strace -e trace=open,close,openat dmidecode
openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
close(3)                                = 0
openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
close(3)                                = 0
# dmidecode 3.1
openat(AT_FDCWD, "/sys/firmware/dmi/tables/smbios_entry_point", O_RDONLY) = 3
close(3)                                = 0
Getting SMBIOS data from sysfs.
SMBIOS 3.0.0 present.
Table at 0x000E0000.

openat(AT_FDCWD, "/sys/firmware/dmi/tables/DMI", O_RDONLY) = 3
close(3)                                = 0
czl@czl-Vostro-3268:~$ sudo strace -e trace=open,close,openat dmidecode
openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
close(3)                                = 0
openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
close(3)                                = 0
# dmidecode 3.1
openat(AT_FDCWD, "/sys/firmware/dmi/tables/smbios_entry_point", O_RDONLY) = 3
close(3)                                = 0
Getting SMBIOS data from sysfs.
SMBIOS 3.0.0 present.
Table at 0x000E0000.

openat(AT_FDCWD, "/sys/firmware/dmi/tables/DMI", O_RDONLY) = 3
close(3)                                = 0

dmidecode的常见用法：

$ dmidecode                                                       # 打印所有硬件信息
$ dmidecode -q                                                  # 打印所有硬件信息，比较简洁
$ dmidecode -h                                                  # 获取帮助
$ dmidecode | grep 'Product Name'         # 以过滤的方式来查看指定的硬件信息
$ dmidecode --type bios                                # 查看BIOS相关的硬件信息
$ dmidecode --type system                          # 查看系统相关的硬件信息
$ dmidecode --type baseboard                  # 查看主板相关的硬件信息
$ dmidecode --type chassis                         # 查看机箱相关的硬件信息
$ dmidecode --type processor                    # 查看处理器相关的硬件信息
$ dmidecode --type memory                      # 查看内存相关的硬件信息
$ dmidecode |grep 'Serial Number'         # 查看主板的序列号
$ dmidecode -s system-serial-number  # 查看系统序列号
$ dmidecode -t 11                                           # 查看OEM信息
$ dmidecode -t 7                                             # 查看L1/L2/L3 Cache信息
$ dmidecode -t 4                                             # 查看CPU信息
$ dmidecode -t slot                                        #查看PCIE Slot槽位信息
$ dmidecode                                                       # 打印所有硬件信息
$ dmidecode -q                                                  # 打印所有硬件信息，比较简洁
$ dmidecode -h                                                  # 获取帮助
$ dmidecode | grep 'Product Name'         # 以过滤的方式来查看指定的硬件信息
$ dmidecode --type bios                                # 查看BIOS相关的硬件信息
$ dmidecode --type system                          # 查看系统相关的硬件信息
$ dmidecode --type baseboard                  # 查看主板相关的硬件信息
$ dmidecode --type chassis                         # 查看机箱相关的硬件信息
$ dmidecode --type processor                    # 查看处理器相关的硬件信息
$ dmidecode --type memory                      # 查看内存相关的硬件信息
$ dmidecode |grep 'Serial Number'         # 查看主板的序列号
$ dmidecode -s system-serial-number  # 查看系统序列号
$ dmidecode -t 11                                           # 查看OEM信息
$ dmidecode -t 7                                             # 查看L1/L2/L3 Cache信息
$ dmidecode -t 4                                             # 查看CPU信息
$ dmidecode -t slot                                        #查看PCIE Slot槽位信息

take get pcie slot for example

czl@czl-Vostro-3268:~$ sudo dmidecode  -t slot
# dmidecode 3.1
Getting SMBIOS data from sysfs.
SMBIOS 3.0.0 present.

Handle 0x0024, DMI type 9, 17 bytes
System Slot Information
    Designation: SLOT1
    Type: x1 PCI Express
    Current Usage: Available
    Length: Short
    ID: 1
    Characteristics:
        3.3 V is provided
        PME signal is supported
    Bus Address: 0000:ff:1f.7

Handle 0x0025, DMI type 9, 17 bytes
System Slot Information
    Designation: SLOT2
    Type: x16 PCI Express 3
    Current Usage: Available
    Length: Long
    ID: 2
    Characteristics:
        3.3 V is provided
        PME signal is supported
    Bus Address: 0000:ff:1f.7
czl@czl-Vostro-3268:~$ sudo dmidecode  -t slot
# dmidecode 3.1
Getting SMBIOS data from sysfs.
SMBIOS 3.0.0 present.

Handle 0x0024, DMI type 9, 17 bytes
System Slot Information
    Designation: SLOT1
    Type: x1 PCI Express
    Current Usage: Available
    Length: Short
    ID: 1
    Characteristics:
        3.3 V is provided
        PME signal is supported
    Bus Address: 0000:ff:1f.7

Handle 0x0025, DMI type 9, 17 bytes
System Slot Information
    Designation: SLOT2
    Type: x16 PCI Express 3
    Current Usage: Available
    Length: Long
    ID: 2
    Characteristics:
        3.3 V is provided
        PME signal is supported
    Bus Address: 0000:ff:1f.7

dmidecode打开文件

sudo strace -tt -T -v -f -e trace=file -o ./strace.log dmidecode
sudo strace -tt -T -v -f -e trace=file -o ./strace.log dmidecode

对应的内核代码在文件drivers/firmware/dmi_scan.c中：

获取机器型号的方法

method 1:

dmesg

method 2:

sudo dmidecode -t 1

内核中获取dmi信息

前面提到，用户空间dmidecode工具是通过/sys/firmware/dmi/tables/smbios_entry_point文件来获取dmi信息的，sysfs是内核空间创建的一个内存文件系统，则必然在内核中也有完备的dmi信息，那么在内核中如何获取呢？

在dmi的内核实现文件dmi_scan.c中，能找到如下几个接口，它们有被作为开放接口export出去，分别是：

u64 dmi_memdev_size(u16 handle);
void dmi_memdev_name(u16 handle, const char **bank, const char **device);
bool dmi_match(enum dmi_field f, const char *str);
int dmi_walk(void (*decode)(const struct dmi_header *, void *);
int dmi_get_bios_year(void);
bool dmi_get_date(int field, int *yearp, int *monthp, int *dayp);
const struct dmi_device *dmi_find_device(int type, const char *name,const struct dmi_device *from);
int dmi_name_in_vendors(const char *str);
const char *dmi_get_system_info(int field);
const struct dmi_system_id *dmi_first_match(const struct dmi_system_id *list);
int dmi_check_system(const struct dmi_system_id *list);
u64 dmi_memdev_size(u16 handle);
void dmi_memdev_name(u16 handle, const char **bank, const char **device);
bool dmi_match(enum dmi_field f, const char *str);
int dmi_walk(void (*decode)(const struct dmi_header *, void *);
int dmi_get_bios_year(void);
bool dmi_get_date(int field, int *yearp, int *monthp, int *dayp);
const struct dmi_device *dmi_find_device(int type, const char *name,const struct dmi_device *from);
int dmi_name_in_vendors(const char *str);
const char *dmi_get_system_info(int field);
const struct dmi_system_id *dmi_first_match(const struct dmi_system_id *list);
int dmi_check_system(const struct dmi_system_id *list);

其中，dmi_get_system_info接口和dmi_check_system接口，是内核中比较常用的几个，dmi_get_system_info 它的参数包含如下类型，在内核中被广泛使用：

dmi_check_system则提供了一个完整的黑/白名单检测语义，用户需要首先将黑/白名单的信息记录在一个struct dmi_system_id类型的数组中，之后以次数组为参数调用dmi_check_system,函数将会返回你当前主班上信息匹配的个数。用户基于此完成应用语义。

典型用法参考drivers/i2c/busses/i2c-piix4.c文件中的用法。

原理

dmi数据存储在哪里？

dmi数据是二进制数据，需要通过架构的IO操作读取到内核，内核为此创建了一个32字节的全局buffer保存，叫做static u8 smbios_entry_point[32];

关键逻辑是首先调用dmi_early_remap对存储smbios信息的区域进行映射，拿到虚拟地址后再dmi_smbios3_present/dmi_present中调用memcpy_fromio读进dmi_early_remap buffer中。最后设置dmi_available为1。

dmidecode就是将smbios_entry_point读取到用户空间解码发挥作用的。

execve("/usr/sbin/dmidecode", ["dmidecode"], 0x7fff725b3940 /* 26 vars */) = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\240\35\2\0\0\0\0\0"..., 832) = 832
close(3)                                = 0
openat(AT_FDCWD, "/sys/firmware/dmi/tables/smbios_entry_point", O_RDONLY) = 3
read(3, "_SM_\7\37\2\7s\0\0\0\0\0\0\0_DMI_\327D*\20\0\16\0\4\1\0", 32) = 31
read(3, "", 1)                          = 0
close(3)                                = 0
openat(AT_FDCWD, "/sys/firmware/dmi/tables/DMI", O_RDONLY) = 3
read(3, "\0\30\0\0\1\2I\352\3\0\220\337\t|\0\0\0\0\201\7\4\6\0\0Phoenix "..., 10820) = 4096
read(3, "RAM slot #33\0\0\21\"]\0:\0\377\377\0\0\0\0\0\0\t\0\1\1"..., 6724) = 4096
read(3, "\0\0\0\0\0NVD #61\0\0\21\"\271\0%\0\377\377 \0 \0\0\0\t\0\1\1"..., 2628) = 2628
read(3, "", 0)                          = 0
close(3)                                = 0
+++ exited with 0 +++
execve("/usr/sbin/dmidecode", ["dmidecode"], 0x7fff725b3940 /* 26 vars */) = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\240\35\2\0\0\0\0\0"..., 832) = 832
close(3)                                = 0
openat(AT_FDCWD, "/sys/firmware/dmi/tables/smbios_entry_point", O_RDONLY) = 3
read(3, "_SM_\7\37\2\7s\0\0\0\0\0\0\0_DMI_\327D*\20\0\16\0\4\1\0", 32) = 31
read(3, "", 1)                          = 0
close(3)                                = 0
openat(AT_FDCWD, "/sys/firmware/dmi/tables/DMI", O_RDONLY) = 3
read(3, "\0\30\0\0\1\2I\352\3\0\220\337\t|\0\0\0\0\201\7\4\6\0\0Phoenix "..., 10820) = 4096
read(3, "RAM slot #33\0\0\21\"]\0:\0\377\377\0\0\0\0\0\0\t\0\1\1"..., 6724) = 4096
read(3, "\0\0\0\0\0NVD #61\0\0\21\"\271\0%\0\377\377 \0 \0\0\0\t\0\1\1"..., 2628) = 2628
read(3, "", 0)                          = 0
close(3)                                = 0
+++ exited with 0 +++

注意其中的raw_table_read函数实现。

除此之外，dmi仅仅是一个 sysfs中创建的子目录

callstack

[  129.107667] Hardware name: Dell Inc. Vostro 3268/0TJYKK, BIOS 1.11.1 12/11/2018
[  129.107667] Call Trace:
[  129.107669]  dump_stack+0x6d/0x8b
[  129.107670]  raw_table_read+0x24/0x30
[  129.107672]  sysfs_kf_bin_read+0x4d/0x80
[  129.107673]  kernfs_fop_read+0xad/0x1a0
[  129.107675]  __vfs_read+0x1b/0x40
[  129.107676]  vfs_read+0x8e/0x130
[  129.107678]  ksys_read+0xa7/0xe0
[  129.107679]  __x64_sys_read+0x1a/0x20
[  129.107681]  do_syscall_64+0x57/0x190
[  129.107682]  entry_SYSCALL_64_after_hwframe+0x5c/0xc1
[  129.107683] RIP: 0033:0x7f01e2dd1031
[  129.107667] Hardware name: Dell Inc. Vostro 3268/0TJYKK, BIOS 1.11.1 12/11/2018
[  129.107667] Call Trace:
[  129.107669]  dump_stack+0x6d/0x8b
[  129.107670]  raw_table_read+0x24/0x30
[  129.107672]  sysfs_kf_bin_read+0x4d/0x80
[  129.107673]  kernfs_fop_read+0xad/0x1a0
[  129.107675]  __vfs_read+0x1b/0x40
[  129.107676]  vfs_read+0x8e/0x130
[  129.107678]  ksys_read+0xa7/0xe0
[  129.107679]  __x64_sys_read+0x1a/0x20
[  129.107681]  do_syscall_64+0x57/0x190
[  129.107682]  entry_SYSCALL_64_after_hwframe+0x5c/0xc1
[  129.107683] RIP: 0033:0x7f01e2dd1031

dmidecode源码

获取源码

wget -c http://download.savannah.gnu.org/releases/dmidecode/dmidecode-3.4.tar.xz
wget -c http://download.savannah.gnu.org/releases/dmidecode/dmidecode-3.4.tar.xz

编译：

$ make
cc -O2 -W -Wall -Wshadow -Wstrict-prototypes -Wpointer-arith -Wcast-qual -Wcast-align -Wwrite-strings -Wmissing-prototypes -Winline -Wundef -D_FILE_OFFSET_BITS=64 -c dmidecode.c -o dmidecode.o
cc -O2 -W -Wall -Wshadow -Wstrict-prototypes -Wpointer-arith -Wcast-qual -Wcast-align -Wwrite-strings -Wmissing-prototypes -Winline -Wundef -D_FILE_OFFSET_BITS=64 -c dmiopt.c -o dmiopt.o
cc -O2 -W -Wall -Wshadow -Wstrict-prototypes -Wpointer-arith -Wcast-qual -Wcast-align -Wwrite-strings -Wmissing-prototypes -Winline -Wundef -D_FILE_OFFSET_BITS=64 -c dmioem.c -o dmioem.o
cc -O2 -W -Wall -Wshadow -Wstrict-prototypes -Wpointer-arith -Wcast-qual -Wcast-align -Wwrite-strings -Wmissing-prototypes -Winline -Wundef -D_FILE_OFFSET_BITS=64 -c dmioutput.c -o dmioutput.o
cc -O2 -W -Wall -Wshadow -Wstrict-prototypes -Wpointer-arith -Wcast-qual -Wcast-align -Wwrite-strings -Wmissing-prototypes -Winline -Wundef -D_FILE_OFFSET_BITS=64 -c util.c -o util.o
cc  dmidecode.o dmiopt.o dmioem.o dmioutput.o util.o -o dmidecode
cc -O2 -W -Wall -Wshadow -Wstrict-prototypes -Wpointer-arith -Wcast-qual -Wcast-align -Wwrite-strings -Wmissing-prototypes -Winline -Wundef -D_FILE_OFFSET_BITS=64 -c biosdecode.c -o biosdecode.o
cc  biosdecode.o util.o -o biosdecode
cc -O2 -W -Wall -Wshadow -Wstrict-prototypes -Wpointer-arith -Wcast-qual -Wcast-align -Wwrite-strings -Wmissing-prototypes -Winline -Wundef -D_FILE_OFFSET_BITS=64 -c ownership.c -o ownership.o
cc  ownership.o util.o -o ownership
cc -O2 -W -Wall -Wshadow -Wstrict-prototypes -Wpointer-arith -Wcast-qual -Wcast-align -Wwrite-strings -Wmissing-prototypes -Winline -Wundef -D_FILE_OFFSET_BITS=64 -c vpddecode.c -o vpddecode.o
cc -O2 -W -Wall -Wshadow -Wstrict-prototypes -Wpointer-arith -Wcast-qual -Wcast-align -Wwrite-strings -Wmissing-prototypes -Winline -Wundef -D_FILE_OFFSET_BITS=64 -c vpdopt.c -o vpdopt.o
cc  vpddecode.o vpdopt.o util.o -o vpddecode

$ make
cc -O2 -W -Wall -Wshadow -Wstrict-prototypes -Wpointer-arith -Wcast-qual -Wcast-align -Wwrite-strings -Wmissing-prototypes -Winline -Wundef -D_FILE_OFFSET_BITS=64 -c dmidecode.c -o dmidecode.o
cc -O2 -W -Wall -Wshadow -Wstrict-prototypes -Wpointer-arith -Wcast-qual -Wcast-align -Wwrite-strings -Wmissing-prototypes -Winline -Wundef -D_FILE_OFFSET_BITS=64 -c dmiopt.c -o dmiopt.o
cc -O2 -W -Wall -Wshadow -Wstrict-prototypes -Wpointer-arith -Wcast-qual -Wcast-align -Wwrite-strings -Wmissing-prototypes -Winline -Wundef -D_FILE_OFFSET_BITS=64 -c dmioem.c -o dmioem.o
cc -O2 -W -Wall -Wshadow -Wstrict-prototypes -Wpointer-arith -Wcast-qual -Wcast-align -Wwrite-strings -Wmissing-prototypes -Winline -Wundef -D_FILE_OFFSET_BITS=64 -c dmioutput.c -o dmioutput.o
cc -O2 -W -Wall -Wshadow -Wstrict-prototypes -Wpointer-arith -Wcast-qual -Wcast-align -Wwrite-strings -Wmissing-prototypes -Winline -Wundef -D_FILE_OFFSET_BITS=64 -c util.c -o util.o
cc  dmidecode.o dmiopt.o dmioem.o dmioutput.o util.o -o dmidecode
cc -O2 -W -Wall -Wshadow -Wstrict-prototypes -Wpointer-arith -Wcast-qual -Wcast-align -Wwrite-strings -Wmissing-prototypes -Winline -Wundef -D_FILE_OFFSET_BITS=64 -c biosdecode.c -o biosdecode.o
cc  biosdecode.o util.o -o biosdecode
cc -O2 -W -Wall -Wshadow -Wstrict-prototypes -Wpointer-arith -Wcast-qual -Wcast-align -Wwrite-strings -Wmissing-prototypes -Winline -Wundef -D_FILE_OFFSET_BITS=64 -c ownership.c -o ownership.o
cc  ownership.o util.o -o ownership
cc -O2 -W -Wall -Wshadow -Wstrict-prototypes -Wpointer-arith -Wcast-qual -Wcast-align -Wwrite-strings -Wmissing-prototypes -Winline -Wundef -D_FILE_OFFSET_BITS=64 -c vpddecode.c -o vpddecode.o
cc -O2 -W -Wall -Wshadow -Wstrict-prototypes -Wpointer-arith -Wcast-qual -Wcast-align -Wwrite-strings -Wmissing-prototypes -Winline -Wundef -D_FILE_OFFSET_BITS=64 -c vpdopt.c -o vpdopt.o
cc  vpddecode.o vpdopt.o util.o -o vpddecode

编译结果有四个目标文件，分别是dmidecode,ownership, vpdecode, biosdecode.

内核中的应用

内核在打印dump_stack时，会输出主板型号，BIOS型号等信息。这些信息的来源即是DMI。

dmi_setup->dump_stack_set_arch_desc.

打印：

dump_stack->dump_stack_set_arch_desc->printk("%sHardware name: %s\n",log_lvl, dump_stack_arch_desc_str);

dump kernel DMI信息

#include <linux/init.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/stat.h>
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/kdev_t.h>
#include <linux/cdev.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/seq_file.h>
#include <linux/sched/signal.h>
#include <linux/proc_fs.h>
#include <linux/pid.h>
#include <linux/pci.h>
#include <linux/usb.h>
#include <linux/kobject.h>
#include <linux/sched/mm.h>
#include <linux/platform_device.h>
#include <linux/netdevice.h>
#include <net/net_namespace.h>
#include <linux/sched/debug.h>
#include <linux/topology.h>
#include <linux/version.h>
#include <linux/fs_struct.h>
#include <linux/mount.h>
#include <linux/i2c.h>
#include <linux/backing-dev-defs.h>
#include <linux/dmi.h>
 
int seqfile_debug_mode = 0;
EXPORT_SYMBOL(seqfile_debug_mode);
module_param(seqfile_debug_mode, int, 0664);

int pid_number = -1;
EXPORT_SYMBOL(pid_number);
module_param(pid_number, int, 0664);
 
static int kobj_created = 0;
static struct kset *class_zilong;
static struct kobject kobj;
static void kill_processes(int pid_nr);
// 开始输出任务列表
// my_seq_ops_start()的返回值，会传递给my_seq_ops_next()的v参数
static void *my_seq_ops_start(struct seq_file *m, loff_t *pos)
{
    loff_t index = *pos;
    struct task_struct *task;
 
    printk("%s line %d, index %lld.count %ld, size %ld here.\n", __func__, __LINE__, index, m->count, m->size);
 
    if(seqfile_debug_mode == 0) {
        // 如果缓冲区不足, seq_file可能会重新调用start()函数,
        // 并且传入的pos是之前已经遍历到的位置,
        // 这里需要根据pos重新计算开始的位置
        for_each_process(task) {
            if (index-- == 0) {
                return task;
            }
        }
    } else {
        return NULL + (*pos == 0);
    }
 
    return NULL;
}
 
// 继续遍历, 直到my_seq_ops_next()放回NULL或者错误
static void *my_seq_ops_next(struct seq_file *m, void *v, loff_t *pos)
{
    struct task_struct *task = NULL;
 
    if(seqfile_debug_mode == 0) {
        task = next_task((struct task_struct *)v);
 
        // 这里加不加好像都没有作用
        ++ *pos;
 
        // 返回NULL, 遍历结束
        if(task == &init_task) {
            return NULL;
        }
    } else {
        ++ *pos;
    }
 
    return task;
}
 
// 遍历完成/出错时seq_file会调用stop()函数
static void my_seq_ops_stop(struct seq_file *m, void *v)
{
 
}

static void pci_reset_sbr(struct pci_dev *dev)
{
    uint16_t ctrl;

    pci_read_config_word(dev, PCI_BRIDGE_CONTROL, &ctrl);
    ctrl |= PCI_BRIDGE_CTL_BUS_RESET;
    pci_write_config_word(dev, PCI_BRIDGE_CONTROL, ctrl);

    msleep(2);

    ctrl &= ~PCI_BRIDGE_CTL_BUS_RESET;
    pci_write_config_word(dev, PCI_BRIDGE_CONTROL, ctrl);
    ssleep(1);
}

static struct pci_dev *g_pci_dev = NULL;
static int lookup_pci_devices_reset(struct device *dev, void *data)
{
    struct seq_file *m = (struct seq_file *)data;
    struct pci_dev *pdev = to_pci_dev(dev);

    seq_printf(m, "%s line %d vendor id 0x%x, device id 0x%x, devname %s.\n", __func__, __LINE__, pdev->vendor, pdev->device, dev_name(&pdev->dev));

    // find the EHCI device.8086:a12f
    //if ((pdev->vendor == 0x1ee0) && (pdev->device == 0xf)) {
    if ((pdev->vendor == 0x168c) && (pdev->device == 0x36)) {
    //if ((pdev->vendor == 0x8086) && (pdev->device == 0xa12f)) {
        seq_printf(m, "%s line %d, do the reset of wireless device, domain 0x%04x, device PCI:%d:%d:%d\n.", \
            __func__, __LINE__, pci_domain_nr(pdev->bus), pdev->bus->number, PCI_SLOT(pdev->devfn), PCI_FUNC(pdev->devfn));
        g_pci_dev = pdev;
    }

    return 0;
}

static unsigned int pci_rescan_bus_bridge_resize_priv(struct pci_dev *bridge)
{
    unsigned int max;
    struct pci_bus *bus = bridge->subordinate;

    max = pci_scan_child_bus(bus);

    pci_assign_unassigned_bridge_resources(bridge);

    pci_bus_add_devices(bus);

    return max;
}

static struct pci_bus *find_pci_root_bus(struct pci_bus *bus)
{
     while (bus->parent) bus = bus->parent;

     return bus;
}
 
static int lookup_pci_devices(struct device *dev, void *data)
{
    struct seq_file *m = (struct seq_file *)data;
    struct pci_dev *pdev = to_pci_dev(dev);
    struct pci_bus *rootbus = NULL;
 
    rootbus = find_pci_root_bus(pdev->bus);

    seq_printf(m, "vendor id 0x%x, device id 0x%x, devname %s.domain: 0x%04x, BDF: %x:%x:%x. sub 0x%p. rootbus number %d, rootbusname %s, bridgename %s. bridge %s.\n", \
            pdev->vendor, pdev->device, dev_name(&pdev->dev),pci_domain_nr(pdev->bus), pdev->bus->number, \
        PCI_SLOT(pdev->devfn), PCI_FUNC(pdev->devfn), pdev->subordinate, rootbus->number, rootbus->name, dev_name(pdev->bus->bridge), dev_name(pdev->bus->bridge));

    if(pdev->bus->self) {
    seq_printf(m,"bridge pdev->bus->self->dev = 0x%px, %s.\n", &pdev->bus->self->dev, dev_name(&pdev->bus->self->dev));
    }

    seq_printf(m, "sr-iov is %d %d.\n", pci_num_vf(pdev), pdev->is_physfn);
    if(dev_is_pf(&pdev->dev)) {
    seq_printf(m, "is pf.\n");
    } else {
    seq_printf(m, "is vf.\n");
    }

    if(pdev->dev.bus->iommu_ops) {
        seq_printf(m, "%s line %d iommu ops is 0x%lx.\n", __func__, __LINE__, (unsigned long)pdev->dev.bus->iommu_ops);
    } else {
        seq_printf(m, "no iommuops.\n");
    }
    if(pdev->dev.dma_ops) {
        seq_printf(m, "%s line %d dma ops is 0x%lx.\n", __func__, __LINE__, (unsigned long)pdev->dev.dma_ops);
    } else {
        seq_printf(m, "no dma ops.\n");
    }

    return 0;
}
 
static int lookup_pci_drivers(struct device_driver *drv, void *data)
{
    struct seq_file *m = (struct seq_file *)data;
    seq_printf(m, "driver name %s.\n", drv->name);
 
    return 0;
}

static int lookup_platform_devices(struct device *dev, void *data)
{
    struct seq_file *m = (struct seq_file *)data;
    struct platform_device *platdev = to_platform_device(dev);
 
    seq_printf(m, "devpath %s.\n", platdev->name);
 
    return 0;
}
 
static int lookup_platform_drivers(struct device_driver *drv, void *data)
{
    struct seq_file *m = (struct seq_file *)data;
    seq_printf(m, "driver name %s.\n", drv->name);
 
    return 0;
}
 
static int list_device_belongs_todriver_pci(struct device *dev, void *p) 
{
    struct seq_file *m = (struct seq_file *)p;
    struct pci_dev *pdev = to_pci_dev(dev);
 
    seq_printf(m, "vendor id 0x%x, device id 0x%x, devname %s.\n", pdev->vendor, pdev->device, dev_name(&pdev->dev));
 
    return 0;
}

static int list_device_belongs_todriver_platform(struct device *dev, void *p) 
{
    struct seq_file *m = (struct seq_file *)p;
    struct platform_device *platdev = to_platform_device(dev);
 
    seq_printf(m, "platdevname %s.\n", platdev->name);
 
    return 0;
}

static int pcie_device_info_find_bridge(struct pci_dev *pdev, void *data)
{
    struct seq_file *m = (struct seq_file *)data;
    struct pci_bus *rootbus = NULL;
    rootbus = pci_find_bus(0, 0);

    if(pci_is_bridge(pdev)){
        seq_printf(m, "bridge find.vendor id 0x%x, device id 0x%x, devname %s. domain:0x%04x, BDF: %x:%x:%x, subordinate 0x%p, busid %d, rootbus %d rootself 0x%p.\n", \
            pdev->vendor, pdev->device, dev_name(&pdev->dev), pci_domain_nr(pdev->bus), pdev->bus->number, PCI_SLOT(pdev->devfn), PCI_FUNC(pdev->devfn), pdev->subordinate, 
        pdev->subordinate->number, rootbus->number, rootbus->self);
    }

    return 0;
}
 
static int pcie_device_info(struct pci_dev *pdev, void *data)
{
    struct seq_file *m = (struct seq_file *)data;
 
    seq_printf(m, "vendor id 0x%04x, device id 0x%04x, devname %s, belongs to bus %16s, parent bus name %6s subordinate 0x%p.\n", \
            pdev->vendor, pdev->device, dev_name(&pdev->dev), pdev->bus->name, pdev->bus->parent? pdev->bus->parent->name : "null", pdev->subordinate);
 
    if(pdev->subordinate) {
        seq_printf(m, "    subordinate have bus name %s.\n", pdev->subordinate->name);
        if(pdev->subordinate->self) {
            seq_printf(m, "        subordinate have dev name %s.\n", dev_name(&pdev->subordinate->self->dev));
            if(pdev->subordinate->self != pdev) {
                seq_printf(m, "            cant happend!\n");
            } else {
                seq_printf(m, "            surely!\n");
            }
        }
 
    } else {
        seq_printf(m, "    subordinate not have.\n");
    }
    
    if(pdev->bus->self) {
        seq_printf(m, "    device belongs to child pci bus %s.\n", dev_name(&pdev->bus->self->dev));
    } else {
        seq_printf(m, "    device belongs to top lvl pci bus.\n");
    }
 
    seq_printf(m, "\n");
    return 0;
}

struct zilong_attribute {
    struct attribute    attr;
    ssize_t (*show)(struct kobject *kobj, struct zilong_attribute *attr, char *buf);
    ssize_t (*store)(struct kobject *dev, struct zilong_attribute *attr,const char *buf, size_t count);
};

#define to_zilong_attr(_attr) container_of(_attr, struct zilong_attribute, attr)
static ssize_t zilong_attr_show(struct kobject *kobj, struct attribute *attr, char *buf)
{
    struct zilong_attribute *zlattr = to_zilong_attr(attr);
    zlattr->show(kobj, zlattr, buf);
    
    return 0;
}

static ssize_t zilong_attr_store(struct kobject *kobj, struct attribute *attr, const char *buf, size_t count)
{
    ssize_t size;

    struct zilong_attribute *zlattr = to_zilong_attr(attr);
    size = zlattr->store(kobj, zlattr, buf, count);

    return size;
}
static const struct sysfs_ops zilong_sysfs_ops = {
    .show   = zilong_attr_show,
    .store  = zilong_attr_store,
};

static struct kobj_type zilong_ktype = {
    .release        = NULL,
    .sysfs_ops      = &zilong_sysfs_ops,
    .namespace      = NULL,
    .get_ownership  = NULL,
};

ssize_t height_show(struct kobject *kobj, struct zilong_attribute *attr, char *buf)
{
    char *p = buf;

    p += sprintf(p, "I am 180 cm tall.\n");

    printk("%s line %d output %ld.\n", __func__, __LINE__, p - buf);
    return p - buf;
}

ssize_t height_store(struct kobject *dev, struct zilong_attribute *attr,const char *buf, size_t count)
{
    unsigned long height = 0;

    sscanf(buf, "%lx", &height);

    if (printk_ratelimit())
    printk("%s line %d, height %ld.\n", __func__, __LINE__, height);

    return count;
}

struct zilong_attribute height = {
    .attr = {
        .name = "height",
        .mode = 0777,
    },
    .show = height_show,
    .store = height_store,
};

static void f(struct super_block *sb, void *data)
{
    struct seq_file *m = (struct seq_file*)data;

    // for the sb->s_root dentry, d_parent is itself.
    seq_dentry(m, sb->s_root, " \t\n\\");
    seq_printf(m, "device %s.\n", sb->s_bdi->dev_name);
}

struct vfsmount *get_path_mount(char *path)
{
    struct path fspath;
    struct vfsmount *mnt;

    int err = kern_path(path, LOOKUP_FOLLOW, &fspath);
    if (err){
        printk(KERN_ERR "failed to get path.\n");
        return NULL;
    }

    mnt = fspath.mnt;

    return mnt;
}

#if 1
struct dentry *get_mount_entry(struct vfsmount *mnt, void **n, struct vfsmount **parent)
{
    void *p = NULL;
    p = mnt;
    mnt = p;
    return NULL;
}
#endif

struct dentry *get_mount_entry(struct vfsmount *mnt, void**, struct vfsmount **parent);
static void hack_mount(struct seq_file *m, struct vfsmount *mnt)
{
    struct path path;
    char buf[64];
    char *name;
    void *ptr;
    struct vfsmount *mt;

    struct dentry *dent = (struct dentry*) (*(unsigned long*)((unsigned long)mnt - sizeof(void*)));
    seq_printf(m, "mnt parent dentry name %s, %s.\n", dent->d_parent->d_name.name, dent->d_name.name);
    dent = get_mount_entry(mnt, &ptr, &mt);
    seq_printf(m, "mnt parent dentry name %s, %s, offset %ld.\n", dent->d_parent->d_name.name, dent->d_name.name, (unsigned long)ptr - (unsigned long)mnt);

    path.mnt = mnt;
    path.dentry=mnt->mnt_root;

    name = d_path(&path, buf, sizeof(buf));
    seq_printf(m, "mount dir is %s.\n", name);
    if(mt){
        struct vfsmount *cd = NULL;
        seq_printf(m, "parent fs is %s,mt=0x%px.\n", mt->mnt_sb->s_type->name,mt);
        get_mount_entry(mt, &ptr, &cd);
        if(cd) {
            seq_printf(m, "parent parent fs is %s cd=0x%px.\n", cd->mnt_sb->s_type->name, cd);
        } else {
            seq_printf(m, "parent parent fs is null.\n");
        }
    }
}

static void check_fs_mount(struct seq_file *m, char *path)
{
    struct vfsmount *mnt, *root;
        struct dentry* dentry = NULL;

    root = current->fs->root.mnt;

    mnt = get_path_mount(path);
    if(mnt){
        seq_printf(m, "fstype %s, info %s, mntroot %s, mntroot 0x%px, superroot %px, root %px.\n", \
                mnt->mnt_sb->s_type->name, mnt->mnt_sb->s_id, mnt->mnt_root->d_name.name, mnt->mnt_root, mnt->mnt_sb->s_root, root);
        seq_printf(m, "fstype %s, info %s, mntroot %s, mntroot 0x%px, superroot %px, root %px,mnt %px.\n", \
                root->mnt_sb->s_type->name, root->mnt_sb->s_id, root->mnt_root->d_name.name, root->mnt_root, root->mnt_sb->s_root, root, mnt);
        if(mnt->mnt_sb->s_root == mnt->mnt_root){
            seq_printf(m, "root identical.\n");
        } else {
            seq_printf(m, "root non-identical.\n");
        }

        dentry = mnt->mnt_root;
            while (dentry->d_parent != dentry) {
                dentry = dentry->d_parent;
            seq_printf(m, "dentry name %s.\n", dentry->d_name.name);
            }
        hack_mount(m, mnt);
    }
}

void list_all_mount_points(struct seq_file *m)
{
    //struct task_struct *task = get_current();

    check_fs_mount(m, "/");
    //check_fs_mount(m, "/home/zlcao/Workspace/linux/ramfs/mountdir");
    check_fs_mount(m, "/dev");
    check_fs_mount(m, "/tmp");
    check_fs_mount(m, "/var");
    check_fs_mount(m, "/dev/pts");
    check_fs_mount(m, "/home/zlcao/Workspace/zlramfs");

    return;
}

static int __process_all_devices(struct device *dev, void *data)
{
    struct seq_file *m = (struct seq_file*)data;
    if(dev->type == &i2c_adapter_type){
        struct i2c_adapter *adap = to_i2c_adapter(dev);
        seq_printf(m, "this is adaptor adaptor name %s dev name %s.\n", adap->name, dev_name(&adap->dev));
    }
    else if(dev->type == &i2c_client_type){
        struct i2c_client *clie = to_i2c_client(dev);
        seq_printf(m, "this is device %s, dev %s.\n", clie->name, dev_name(&clie->dev));
    }
    else
        seq_printf(m, "cant hanppend.\n");

    return 0;
}

static void probe_i2c_adaptor(struct seq_file *m, int id)
{
    struct i2c_adapter *adap;
    adap = i2c_get_adapter(id);
    if(!adap){
        seq_printf(m, "cant find i2c adaptor 6.\n");
        return;
    }
    //i2c_transfer(adap, msg, ...);
    seq_printf(m, "i2c adaptor name %s, i2c dev name %s.\n", adap->name, dev_name(&adap->dev));
    i2c_put_adapter(adap);

    i2c_for_each_dev(m, __process_all_devices);
}

void list_all_i2c_devices(struct seq_file *m)
{
    probe_i2c_adaptor(m, 0);
    probe_i2c_adaptor(m, 1);
    probe_i2c_adaptor(m, 2);
    probe_i2c_adaptor(m, 3);
    probe_i2c_adaptor(m, 4);
    probe_i2c_adaptor(m, 5);
    probe_i2c_adaptor(m, 6);
    probe_i2c_adaptor(m, 7);
    return;
}

typedef struct dmi_info_entry
{
    int id;
    char *name;
}dmi_info_entry_t;

#define DMI_ENTRY(idx) {.id = idx, .name = #idx}

dmi_info_entry_t dmi_tbl[] = {
    DMI_ENTRY(DMI_NONE),
    DMI_ENTRY(DMI_BIOS_VENDOR),
    DMI_ENTRY(DMI_BIOS_VERSION),
    DMI_ENTRY(DMI_BIOS_DATE),
    DMI_ENTRY(DMI_BIOS_RELEASE),
    DMI_ENTRY(DMI_EC_FIRMWARE_RELEASE),
    DMI_ENTRY(DMI_SYS_VENDOR),
    DMI_ENTRY(DMI_PRODUCT_NAME),
    DMI_ENTRY(DMI_PRODUCT_VERSION),
    DMI_ENTRY(DMI_PRODUCT_SERIAL),
    DMI_ENTRY(DMI_PRODUCT_UUID),
    DMI_ENTRY(DMI_PRODUCT_SKU),
    DMI_ENTRY(DMI_PRODUCT_FAMILY),
    DMI_ENTRY(DMI_BOARD_VENDOR),
    DMI_ENTRY(DMI_BOARD_NAME),
    DMI_ENTRY(DMI_BOARD_VERSION),
    DMI_ENTRY(DMI_BOARD_SERIAL),
    DMI_ENTRY(DMI_BOARD_ASSET_TAG),
    DMI_ENTRY(DMI_CHASSIS_VENDOR),
    DMI_ENTRY(DMI_CHASSIS_TYPE),
    DMI_ENTRY(DMI_CHASSIS_VERSION),
    DMI_ENTRY(DMI_CHASSIS_SERIAL),
    DMI_ENTRY(DMI_CHASSIS_ASSET_TAG),
    //DMI_ENTRY(DMI_STRING_MAX),
    DMI_ENTRY(DMI_OEM_STRING),
};

void dmi_info_verbose(struct seq_file *m)
{
    int i;
    
    for (i = 0; i < sizeof(dmi_tbl)/sizeof(dmi_info_entry_t); i ++){
        const char *s = dmi_get_system_info(dmi_tbl[i].id);
        if(s)
            seq_printf(m, "DMI %s INFO: %s.\n", dmi_tbl[i].name, s);
        else
            seq_printf(m, "DMI %s INFO is null.\n", dmi_tbl[i].name);
    }

    return;
}
void list_all_mount_device(struct seq_file *m)
{
#if 0
    struct nsproxy *nsp;
    struct task_struct *task = current;
    struct mnt_namespace *ns = NULL;
    struct list_head *p;
    struct mount *mnt, *ret = NULL;

    task_lock(task);
    nsp = task->nsproxy;
    if (!nsp || !nsp->mnt_ns) {
        printk("%s line %d. return error.\n", __func__, __LINE__);
        task_unlock(task);
        put_task_struct(task);
        return;
    }
    ns = nsp->mnt_ns;
    if (!task->fs) {
        printk("%s line %d. return error.\n", __func__, __LINE__);
        task_unlock(task);
        put_task_struct(task);
        return;
    }
    task_unlock(task);
    put_task_struct(task);

    list_for_each_continue(p, &ns->list) {
        mnt = list_entry(p, typeof(*mnt), mnt_list);
    }
    return;
#else
    struct file_system_type *fs_type;
    fs_type = get_fs_type("ext4");
    if(fs_type == NULL){
        printk("%s line %d. return error.\n", __func__, __LINE__);
        return;
    }

    iterate_supers_type(fs_type, f, m);
#endif
}
// 此函数将数据写入`seq_file`内部的缓冲区
// `seq_file`会在合适的时候把缓冲区的数据拷贝到应用层
// 参数@V是start/next函数的返回值
static int my_seq_ops_show(struct seq_file *m, void *v)
{
    struct task_struct *task = NULL;
    struct task_struct *tsk = NULL;
    struct task_struct *p = NULL;
    struct file *file = m->private;
    struct pid *session = NULL;
 
    if(seqfile_debug_mode == 0) {
        seq_puts(m, " file=");
        seq_file_path(m, file, "\n");
        seq_putc(m, ' ');
 
        task = (struct task_struct *)v;
        session = task_session(task);
        tsk = pid_task(session, PIDTYPE_PID);
        if(task->flags & PF_KTHREAD) {
            seq_printf(m, "Kernel thread output: PID=%u, task: %s, index=%lld, read_pos=%lld, %s.\n", task_tgid_nr(task),/* task->tgid,*/
                task->comm, m->index, m->read_pos, tsk? "has session" : "no session");
        } else {
            seq_printf(m, "User thread: PID=%u, task: %s, index=%lld, read_pos=%lld %s.\n", task_tgid_nr(task), /* task->tgid,*/
                task->comm, m->index, m->read_pos, tsk? "has session" : "no session");
        }

    seq_printf(m, "==================\n");
    sched_show_task(task);
    } else if(seqfile_debug_mode == 1) {
        struct task_struct *g, *p;
        static int oldcount = 0;
        static int entercount = 0;
        char *str;
 
        printk("%s line %d here enter %d times.\n", __func__, __LINE__, ++ entercount);
        seq_printf(m, "%s line %d here enter %d times.\n", __func__, __LINE__, ++ entercount);
 
        rcu_read_lock();
        for_each_process_thread(g, p) {
            struct task_struct *session = pid_task(task_session(g), PIDTYPE_PID);
            struct task_struct *thread = pid_task(task_session(p), PIDTYPE_PID);
            struct task_struct *ggroup = pid_task(task_pgrp(g), PIDTYPE_PID);
            struct task_struct *pgroup = pid_task(task_pgrp(p), PIDTYPE_PID);
            struct pid * pid = task_session(g);
 
            if(list_empty(&p->tasks)) {
                str = "empty";
            } else {
                str = "not empty";
            }
            seq_printf(m, "process %s(pid %d tgid %d,cpu%d) thread %s(pid %d tgid %d,cpu%d),threadnum %d, %d. tasks->prev = %p, \
                    tasks->next = %p, p->tasks=%p, %s, process parent %s(pid %d tgid %d), thread parent%s(pid %d, tgid %d, files %p\n)",
                    g->comm, task_pid_nr(g), task_tgid_nr(g), task_cpu(g), \
                    p->comm, task_pid_nr(p), task_tgid_nr(p), task_cpu(p), \
                    get_nr_threads(g), get_nr_threads(p), p->tasks.prev, p->tasks.next, &p->tasks, str, g->real_parent->comm, \
                    task_pid_nr(g->real_parent),task_tgid_nr(g->real_parent), p->real_parent->comm, task_pid_nr(p->real_parent), task_tgid_nr(p->real_parent), p->files);
 
            if(ggroup) {
                seq_printf(m, "ggroup(pid %d tgid %d).", task_pid_nr(ggroup),task_tgid_nr(ggroup));
            }
 
            if(pgroup) {
                seq_printf(m, "pgroup(pid %d tgid %d).", task_pid_nr(pgroup),task_tgid_nr(pgroup));
            }
 
            seq_printf(m, "current smp processor id %d.", smp_processor_id());
            if(thread) {
                seq_printf(m, "thread session %s(%d).", thread->comm, task_pid_nr(thread));
            }
            if(session) {
                seq_printf(m, "process session %s(%d).", session->comm, task_pid_nr(session));
            }
 
            if(oldcount == 0 || oldcount != m->size) {
                printk("%s line %d, m->count %ld, m->size %ld.", __func__, __LINE__, m->count, m->size);
                oldcount = m->size;
            }
 
            if(pid){
                seq_printf(m, "pid task %p,pgid task %p, psid_task %p", pid_task(pid, PIDTYPE_PID), pid_task(pid, PIDTYPE_PGID), pid_task(pid, PIDTYPE_SID));
                seq_printf(m, "pid task %s,pgid task %s, psid_task %s", pid_task(pid, PIDTYPE_PID)->comm, pid_task(pid, PIDTYPE_PGID)->comm, pid_task(pid, PIDTYPE_SID)->comm);
            }
            seq_printf(m, "\n");
        }
 
        rcu_read_unlock();
    } else if(seqfile_debug_mode == 2) {
        for_each_process(task) {
            struct pid *pgrp = task_pgrp(task);
 
            seq_printf(m, "Group Header %s(%d,cpu%d):\n", task->comm, task_pid_nr(task), task_cpu(task));
            do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
                seq_printf(m, "      process %s(%d,cpu%d) thread %s(%d,cpu%d),threadnum %d, %d.\n",
                    task->comm, task_pid_nr(task), task_cpu(task), \
                    p->comm, task_pid_nr(p), task_cpu(p), \
                    get_nr_threads(task), get_nr_threads(p));
            } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
        }
    } else if (seqfile_debug_mode == 3) {
        for_each_process(task) {
            struct pid *session = task_session(task);
            struct task_struct *tsk = pid_task(session, PIDTYPE_PID);
            if(tsk) {
                seq_printf(m, "session task %s(%d,cpu%d):", tsk->comm, task_pid_nr(tsk), task_cpu(tsk));
            } else {
                seq_printf(m, "process %s(%d,cpu%d) has no session task.", task->comm, task_pid_nr(task), task_cpu(task));
            }
 
            seq_printf(m, "session header %s(%d,cpu%d):\n", task->comm, task_pid_nr(task), task_cpu(task));
            do_each_pid_task(session, PIDTYPE_SID, p) {
                seq_printf(m, "      process %s(%d,cpu%d) thread %s(%d,cpu%d),threadnum %d, %d, spidtask %s(%d,%d).\n",
                    task->comm, task_pid_nr(task), task_cpu(task), \
                    p->comm, task_pid_nr(p), task_cpu(p), \
                    get_nr_threads(task), get_nr_threads(p), pid_task(session, PIDTYPE_SID)->comm, pid_task(session, PIDTYPE_SID)->tgid, pid_task(session, PIDTYPE_SID)->pid);
                if(pid_task(session, PIDTYPE_PID)) {
                    seq_printf(m, "pidtask %s(%d,%d).\n", pid_task(session, PIDTYPE_PID)->comm, pid_task(session, PIDTYPE_PID)->tgid, pid_task(session, PIDTYPE_PID)->pid);
                }
            } while_each_pid_task(pgrp, PIDTYPE_SID, p);
        }
    } else if(seqfile_debug_mode == 4) {
        struct task_struct *thread, *child;
        for_each_process(task) {
            seq_printf(m, "process %s(%d,cpu%d):\n", task->comm, task_pid_nr(task), task_cpu(task));
            for_each_thread(task, thread) {
                list_for_each_entry(child, &thread->children, sibling) {
                    seq_printf(m, "      thread %s(%d,cpu%d) child %s(%d,cpu%d),threadnum %d, %d.\n",
                        thread->comm, task_pid_nr(thread), task_cpu(thread), \
                        child->comm, task_pid_nr(child), task_cpu(child), \
                        get_nr_threads(thread), get_nr_threads(child));
                }
            }
        }
    } else if(seqfile_debug_mode == 5) { 
        struct task_struct *g, *t;
        do_each_thread (g, t) {
            seq_printf(m, "Process %s(%d cpu%d), thread %s(%d cpu%d), threadnum %d.\n", g->comm, task_pid_nr(g), task_cpu(g), t->comm, task_pid_nr(t), task_cpu(t), get_nr_threads(g));
        } while_each_thread (g, t);
    } else if(seqfile_debug_mode == 6) {
        for_each_process(task) {
            struct pid *pid = task_pid(task);
 
            seq_printf(m, "Process %s(%d,cpu%d) pid %d, tgid %d:\n", task->comm, task_pid_nr(task), task_cpu(task), task_pid_vnr(task), task_tgid_vnr(task));
            do_each_pid_task(pid, PIDTYPE_TGID, p) {
                seq_printf(m, "      process %s(%d,cpu%d) thread %s(%d,cpu%d),threadnum %d, %d. pid %d, tgid %d\n",
                        task->comm, task_pid_nr(task), task_cpu(task), \
                        p->comm, task_pid_nr(p), task_cpu(p), \
                        get_nr_threads(task), get_nr_threads(p), task_pid_vnr(p), task_tgid_vnr(p));
            } while_each_pid_task(pid, PIDTYPE_TGID, p);
        }
    } else if(seqfile_debug_mode == 7) {
        for_each_process(task) {
            struct pid *pid = task_pid(task);
 
            seq_printf(m, "Process %s(%d,cpu%d) pid %d, tgid %d:\n", task->comm, task_pid_nr(task), task_cpu(task), task_pid_vnr(task), task_tgid_vnr(task));
            do_each_pid_task(pid, PIDTYPE_PID, p) {
                seq_printf(m, "      process %s(%d,cpu%d) thread %s(%d,cpu%d),threadnum %d, %d. pid %d, tgid %d\n",
                    task->comm, task_pid_nr(task), task_cpu(task), \
                    p->comm, task_pid_nr(p), task_cpu(p), \
                    get_nr_threads(task), get_nr_threads(p), task_pid_vnr(p), task_tgid_vnr(p));
            } while_each_pid_task(pid, PIDTYPE_PID, p);
        }
    } else if(seqfile_debug_mode == 8) {
        bus_for_each_dev(&pci_bus_type, NULL, (void*)m, lookup_pci_devices);
        bus_for_each_drv(&pci_bus_type, NULL, (void*)m, lookup_pci_drivers);
        // class_find_device.
        // class_find_device_by_name.
        // class_for_each_device.
    } else if(seqfile_debug_mode == 9) {
        struct device_driver *drv; 
    int ret;

        drv = driver_find("pcieport", &pci_bus_type);
        ret = driver_for_each_device(drv, NULL, (void*)m, list_device_belongs_todriver_pci);
    } else if(seqfile_debug_mode == 10) {
        for_each_process(task) {
#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 7, 0)
            seq_printf(m, "Process %s(%d),state 0x%08x, exit_state 0x%08x, refcount %d, usage %d rcucount %d.", \
                task->comm, task->tgid, task->__state, task->exit_state, refcount_read(&task->stack_refcount), refcount_read(&task->usage), refcount_read(&task->rcu_users));
#else
            seq_printf(m, "Process %s(%d),state 0x%lx, exit_state 0x%08x, refcount %d, usage %d rcucount %d.", \
                task->comm, task->tgid, task->state, task->exit_state, refcount_read(&task->stack_refcount), refcount_read(&task->usage), refcount_read(&task->rcu_users));
#endif
            if(task->parent) {
                seq_printf(m, "parent name %s pid %d.\n", task->parent->comm, task->parent->tgid);
             } else {
                seq_printf(m, "no parent.\n");
            }
        }
    } else if(seqfile_debug_mode == 11) {
        struct pci_bus *bus;
        list_for_each_entry(bus, &pci_root_buses, node) {
            seq_printf(m, "pcibus name %s.\n", bus->name);
            pci_walk_bus(bus, pcie_device_info, (void*)m);
        }
    } else if(seqfile_debug_mode == 12) {
        struct device_driver *drv; 
    int ret;
        // EXPORT_SYMBOL(usb_bus_type);
        // bus_for_each_dev(&usb_bus_type, NULL, (void*)m, lookup_usb_devices);
        // bus_for_each_drv(&usb_bus_type, NULL, (void*)m, lookup_usb_drivers);
        bus_for_each_dev(&platform_bus_type, NULL, (void*)m, lookup_platform_devices);
        bus_for_each_drv(&platform_bus_type, NULL, (void*)m, lookup_platform_drivers);

        drv = driver_find("demo_platform", &platform_bus_type);
        ret = driver_for_each_device(drv, NULL, (void*)m, list_device_belongs_todriver_platform);
    } else if(seqfile_debug_mode == 13) {
        int ret;

        class_zilong = kset_create_and_add("zilong_class", NULL, NULL);
        if (!class_zilong) {
            printk("%s line %d, fatal error, create class failure.\n", __func__, __LINE__);
            return -ENOMEM;
        }

        ret = kobject_init_and_add(&kobj, &zilong_ktype, &class_zilong->kobj, "%s-%d", "zilong", 1);
        if(ret < 0) {
            printk("%s line %d, fatal error, create kobject failure.\n", __func__, __LINE__);
            return -ENOMEM;
        }

        kobj_created = 1;
        ret = sysfs_create_file(&kobj, &height.attr);
        if(ret != 0){
            printk("%s line %d, fatal error, create sysfs attribute failure.\n", __func__, __LINE__);
            return -ENOMEM;
        }
        kobj_created = 1;
    } else if(seqfile_debug_mode == 14) {
        // cad pid is process 1 pid.
        int ret = kill_cad_pid(SIGINT, 1);
        printk("%s lne %d ret %d.\n", __func__, __LINE__, ret);
    } else if(seqfile_debug_mode == 15) {
        kill_processes(pid_number);
    } else if(seqfile_debug_mode == 16) {
        struct pci_dev *pdev    = NULL;
        struct pci_dev *pparent = NULL;
        struct pci_bus *bus     = NULL;
        struct pci_bus *rootbus = NULL;
        struct pci_bus *findbus = NULL;
    
        findbus = pci_find_bus(0, 0);

        list_for_each_entry(rootbus, &pci_root_buses, node) {
            seq_printf(m, "pcibus name %s bus %p, findbus %p.\n", rootbus->name, rootbus, findbus);
            break;
        }

        bus_for_each_dev(&pci_bus_type, NULL, (void*)m, lookup_pci_devices_reset);

        pdev = g_pci_dev;
        if(pdev == NULL) {
            printk("%s line %d, return null.\n", __func__, __LINE__);
            return -1;
        }

        pci_reset_sbr(pdev);

        pci_lock_rescan_remove();
        pci_stop_and_remove_bus_device(pdev);
        pci_unlock_rescan_remove();

        bus = pdev->bus;
        //if (!pci_is_root_bus(bus) && list_empty(&bus->devices))
        if (0)
        {
            printk("%s line %d, lightweight rescan.\n", __func__,  __LINE__);
            pci_lock_rescan_remove();
            pci_rescan_bus_bridge_resize_priv(bus->self);
            pci_unlock_rescan_remove();
        } else {
            printk("%s line %d, rescan.\n", __func__,  __LINE__);
            if(bus->self) {
                bus = bus->self->bus;
                pparent = bus->self;
            }

            seq_printf(m, "%s line %d, do the reset of wireless device, device PCI BUS No.:%d. busname %s, bus %p.\n.", \
                    __func__, __LINE__, bus->number, bus->name, bus);

            if(pparent && pparent->bus) {
                seq_printf(m, "%s line %d, do the reset of wireless device, device PCI:0x%04x:%d:%d.%d\n.", \
                    __func__, __LINE__, pci_domain_nr(pparent->bus), pparent->bus->number, PCI_SLOT(pparent->devfn), PCI_FUNC(pparent->devfn));
            }

            if(bus == rootbus) {
                seq_printf(m, "warnings: reset root bus.\n");
            }

            pci_lock_rescan_remove();
            pci_rescan_bus(bus);
            pci_unlock_rescan_remove();
        }
    } else if(seqfile_debug_mode == 17) {
        struct pci_bus *pbus = NULL;

        while ((pbus = pci_find_next_bus(pbus)) != NULL) {
            seq_printf(m, "find bus %s.\n", pbus->name);  
        }

        list_for_each_entry(pbus, &pci_root_buses, node) {
            seq_printf(m, "pcibus name %s.\n", pbus->name);
            pci_walk_bus(pbus, pcie_device_info_find_bridge, (void*)m);
        }

        bus_for_each_dev(&pci_bus_type, NULL, (void*)m, lookup_pci_devices);
    } else if(seqfile_debug_mode == 18) {
        struct net *net;
        struct net_device *ndev;

        for_each_net(net)
            for_each_netdev(net, ndev) {
                seq_printf(m, "%s line %d, ndev->name %s. net 0x%p.\n", __func__, __LINE__, ndev->name, net);
            }
    } else if(seqfile_debug_mode == 19) {
    unsigned long *p;
    const struct cpumask *mask = cpu_cpu_mask(0);
    p = (unsigned long*)mask;
    seq_printf(m, "mask 0x%lx.\n", p[0]);
    } else if(seqfile_debug_mode == 20) {
    struct task_struct *process, *thread;
        rcu_read_lock();
        for_each_process_thread(process, thread) { 
            if (unlikely(thread->flags & PF_VCPU)) {
#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 7, 0)
            seq_printf(m, "%s line %d, comm %s, pid %d, is %s thread state 0x%x, proces %s(%d).\n", 
                    __func__, __LINE__, thread->comm, thread->pid, thread->mm? "user" : "kernel",thread->__state, process->comm, process->pid);
#else
            seq_printf(m, "%s line %d, comm %s, pid %d, is %s thread state 0x%lx, proces %s(%d).\n", 
                    __func__, __LINE__, thread->comm, thread->pid, thread->mm? "user" : "kernel",thread->state, process->comm, process->pid);
#endif
        }
       }
       rcu_read_unlock(); 
    } else if(seqfile_debug_mode == 21) {
        list_all_mount_device(m);
    } else if(seqfile_debug_mode == 22) {
        list_all_mount_points(m);
    } else if(seqfile_debug_mode == 23) {
        list_all_i2c_devices(m);
    } else if(seqfile_debug_mode == 24) {
     dmi_info_verbose(m);
    } else {
        printk("%s line %d,cant be here, seqfile_debug_mode = %d.\n", __func__, __LINE__, seqfile_debug_mode);
    }
 
    return 0;
}

static struct task_struct *find_lock_task_mm(struct task_struct *p)
{
    struct task_struct *t;

    rcu_read_lock();
    for_each_thread(p, t) {
        task_lock(t);
        if (likely(t->mm))
            goto found;
        task_unlock(t);
    }

    t = NULL;
found:
    rcu_read_unlock();
    return t;
}  

static bool process_shares_task_mm(struct task_struct *p, struct mm_struct *mm)
{
    struct task_struct *t;
    for_each_thread(p, t) {
        struct mm_struct *t_mm = READ_ONCE(t->mm);
        if (t_mm)
            return t_mm == mm;
    }
    return false;
} 

static void kill_processes(int pid_nr)
{
    struct task_struct *victim;
    struct task_struct *p;
    struct mm_struct *mm;
    int old_cnt,new_cnt;

    victim = get_pid_task(find_vpid(pid_nr), PIDTYPE_PID);
    if(victim == NULL) {
        printk("%s line %d,return.\n", __func__, __LINE__);
        return;
    }

    printk("%s line %d, task has live %d threads total.\n", __func__, __LINE__, atomic_read(&victim->signal->live));

    p = find_lock_task_mm(victim);
    if (!p) {
        put_task_struct(victim);
        return;
    } else {
        get_task_struct(p);
        put_task_struct(victim);
        victim = p;
    }

    mm = victim->mm;
    mmgrab(mm);

    kill_pid(find_vpid(pid_nr), SIGKILL, 1);
    task_unlock(victim);

    rcu_read_lock();
    for_each_process(p) {
        if (!process_shares_task_mm(p, mm))
            continue;
        if (same_thread_group(p, victim))
            continue;
        if (unlikely(p->flags & PF_KTHREAD))
            continue;
        kill_pid(get_pid(task_pid(p)), SIGKILL, 1);
   }

   rcu_read_unlock(); 
   mmdrop(mm);

   old_cnt = atomic_read(&victim->signal->live);
   while((new_cnt=atomic_read(&victim->signal->live))) {
    if(new_cnt != old_cnt) {
            printk("%s line %d, live %d.\n", __func__, __LINE__, atomic_read(&victim->signal->live));
        old_cnt = new_cnt;
    }
   }

   put_task_struct(victim);
}
 
static const struct seq_operations my_seq_ops = {
    .start  = my_seq_ops_start,
    .next   = my_seq_ops_next,
    .stop   = my_seq_ops_stop,
    .show   = my_seq_ops_show,
};

static int proc_seq_open(struct inode *inode, struct file *file)
{
    int ret;
    struct seq_file *m;
 
    ret = seq_open(file, &my_seq_ops);
    if(!ret) {
        m = file->private_data; 
        m->private = file;
    }
 
    return ret;
}
 
static ssize_t proc_seq_write(struct file *file, const char __user *buffer, size_t count, loff_t *pos)
{
    char debug_string[16];
    int debug_no;
 
    memset(debug_string, 0x00, sizeof(debug_string));
    if (count >= sizeof(debug_string)) {
        printk("%s line %d, fata error, write count exceed max buffer size.\n", __func__, __LINE__);
        return -EINVAL;
    }
 
    if (copy_from_user(debug_string, buffer, count)) {
        printk("%s line %d, fata error, copy from user failure.\n", __func__, __LINE__);
        return -EFAULT;
    }
 
    if (sscanf(debug_string, "%d", &debug_no) <= 0) {
        printk("%s line %d, fata error, read debugno failure.\n", __func__, __LINE__);
        return -EFAULT;
    }
 
    seqfile_debug_mode = debug_no;
 
    //printk("%s line %d, debug_no %d.\n", __func__, __LINE__, debug_no);
 
    return count;
}
 
static ssize_t proc_seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
{
    ssize_t ret;
 
    printk("%s line %d enter, fuck size %lld size %ld.\n", __func__, __LINE__, *ppos, size);
    ret = seq_read(file, buf, size, ppos);
    printk("%s line %d exit, fuck size %lld size %ld,ret = %ld.\n", __func__, __LINE__, *ppos, size, ret);
 
    return ret;
}
 
#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 7, 0)
static const struct proc_ops seq_proc_ops_new = {
    .proc_open      = proc_seq_open,
    .proc_read      = proc_seq_read,
    .proc_lseek     = seq_lseek,
    .proc_release   = seq_release,
    .proc_write     = proc_seq_write,
};
#else
static struct file_operations seq_proc_ops = {
    .owner      = THIS_MODULE,
    .open       = proc_seq_open,
    .release    = seq_release,
    .read       = proc_seq_read,
    .write      = proc_seq_write,
    .llseek     = seq_lseek,
    .unlocked_ioctl = NULL,
};
#endif
 
static struct proc_dir_entry * entry;
static int proc_hook_init(void)
{
    printk("%s line %d, init. seqfile_debug_mode = %d.\n", __func__, __LINE__, seqfile_debug_mode);

#if 1
#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 7, 0)
    entry = proc_create("dumptask", 0644, NULL, &seq_proc_ops_new);
#else
    entry = proc_create("dumptask", 0644, NULL, &seq_proc_ops);
#endif
#else
    entry = proc_create_seq("dumptask", 0644, NULL, &my_seq_ops);
#endif
    return 0;
}
 
static void proc_hook_exit(void)
{
    if(kobj_created) {
        kobject_del(&kobj);
        kset_unregister(class_zilong);
    }

    proc_remove(entry);
 
    printk("%s line %d, exit.\n", __func__, __LINE__);
 
    return;
}
 
module_init(proc_hook_init);
module_exit(proc_hook_exit);
MODULE_AUTHOR("zlcao");
MODULE_LICENSE("GPL");
#include <linux/init.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/stat.h>
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/kdev_t.h>
#include <linux/cdev.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/seq_file.h>
#include <linux/sched/signal.h>
#include <linux/proc_fs.h>
#include <linux/pid.h>
#include <linux/pci.h>
#include <linux/usb.h>
#include <linux/kobject.h>
#include <linux/sched/mm.h>
#include <linux/platform_device.h>
#include <linux/netdevice.h>
#include <net/net_namespace.h>
#include <linux/sched/debug.h>
#include <linux/topology.h>
#include <linux/version.h>
#include <linux/fs_struct.h>
#include <linux/mount.h>
#include <linux/i2c.h>
#include <linux/backing-dev-defs.h>
#include <linux/dmi.h>
 
int seqfile_debug_mode = 0;
EXPORT_SYMBOL(seqfile_debug_mode);
module_param(seqfile_debug_mode, int, 0664);

int pid_number = -1;
EXPORT_SYMBOL(pid_number);
module_param(pid_number, int, 0664);
 
static int kobj_created = 0;
static struct kset *class_zilong;
static struct kobject kobj;
static void kill_processes(int pid_nr);
// 开始输出任务列表
// my_seq_ops_start()的返回值，会传递给my_seq_ops_next()的v参数
static void *my_seq_ops_start(struct seq_file *m, loff_t *pos)
{
    loff_t index = *pos;
    struct task_struct *task;
 
    printk("%s line %d, index %lld.count %ld, size %ld here.\n", __func__, __LINE__, index, m->count, m->size);
 
    if(seqfile_debug_mode == 0) {
        // 如果缓冲区不足, seq_file可能会重新调用start()函数,
        // 并且传入的pos是之前已经遍历到的位置,
        // 这里需要根据pos重新计算开始的位置
        for_each_process(task) {
            if (index-- == 0) {
                return task;
            }
        }
    } else {
        return NULL + (*pos == 0);
    }
 
    return NULL;
}
 
// 继续遍历, 直到my_seq_ops_next()放回NULL或者错误
static void *my_seq_ops_next(struct seq_file *m, void *v, loff_t *pos)
{
    struct task_struct *task = NULL;
 
    if(seqfile_debug_mode == 0) {
        task = next_task((struct task_struct *)v);
 
        // 这里加不加好像都没有作用
        ++ *pos;
 
        // 返回NULL, 遍历结束
        if(task == &init_task) {
            return NULL;
        }
    } else {
        ++ *pos;
    }
 
    return task;
}
 
// 遍历完成/出错时seq_file会调用stop()函数
static void my_seq_ops_stop(struct seq_file *m, void *v)
{
 
}

static void pci_reset_sbr(struct pci_dev *dev)
{
    uint16_t ctrl;

    pci_read_config_word(dev, PCI_BRIDGE_CONTROL, &ctrl);
    ctrl |= PCI_BRIDGE_CTL_BUS_RESET;
    pci_write_config_word(dev, PCI_BRIDGE_CONTROL, ctrl);

    msleep(2);

    ctrl &= ~PCI_BRIDGE_CTL_BUS_RESET;
    pci_write_config_word(dev, PCI_BRIDGE_CONTROL, ctrl);
    ssleep(1);
}

static struct pci_dev *g_pci_dev = NULL;
static int lookup_pci_devices_reset(struct device *dev, void *data)
{
    struct seq_file *m = (struct seq_file *)data;
    struct pci_dev *pdev = to_pci_dev(dev);

    seq_printf(m, "%s line %d vendor id 0x%x, device id 0x%x, devname %s.\n", __func__, __LINE__, pdev->vendor, pdev->device, dev_name(&pdev->dev));

    // find the EHCI device.8086:a12f
    //if ((pdev->vendor == 0x1ee0) && (pdev->device == 0xf)) {
    if ((pdev->vendor == 0x168c) && (pdev->device == 0x36)) {
    //if ((pdev->vendor == 0x8086) && (pdev->device == 0xa12f)) {
        seq_printf(m, "%s line %d, do the reset of wireless device, domain 0x%04x, device PCI:%d:%d:%d\n.", \
            __func__, __LINE__, pci_domain_nr(pdev->bus), pdev->bus->number, PCI_SLOT(pdev->devfn), PCI_FUNC(pdev->devfn));
        g_pci_dev = pdev;
    }

    return 0;
}

static unsigned int pci_rescan_bus_bridge_resize_priv(struct pci_dev *bridge)
{
    unsigned int max;
    struct pci_bus *bus = bridge->subordinate;

    max = pci_scan_child_bus(bus);

    pci_assign_unassigned_bridge_resources(bridge);

    pci_bus_add_devices(bus);

    return max;
}

static struct pci_bus *find_pci_root_bus(struct pci_bus *bus)
{
     while (bus->parent) bus = bus->parent;

     return bus;
}
 
static int lookup_pci_devices(struct device *dev, void *data)
{
    struct seq_file *m = (struct seq_file *)data;
    struct pci_dev *pdev = to_pci_dev(dev);
    struct pci_bus *rootbus = NULL;
 
    rootbus = find_pci_root_bus(pdev->bus);

    seq_printf(m, "vendor id 0x%x, device id 0x%x, devname %s.domain: 0x%04x, BDF: %x:%x:%x. sub 0x%p. rootbus number %d, rootbusname %s, bridgename %s. bridge %s.\n", \
            pdev->vendor, pdev->device, dev_name(&pdev->dev),pci_domain_nr(pdev->bus), pdev->bus->number, \
        PCI_SLOT(pdev->devfn), PCI_FUNC(pdev->devfn), pdev->subordinate, rootbus->number, rootbus->name, dev_name(pdev->bus->bridge), dev_name(pdev->bus->bridge));

    if(pdev->bus->self) {
    seq_printf(m,"bridge pdev->bus->self->dev = 0x%px, %s.\n", &pdev->bus->self->dev, dev_name(&pdev->bus->self->dev));
    }

    seq_printf(m, "sr-iov is %d %d.\n", pci_num_vf(pdev), pdev->is_physfn);
    if(dev_is_pf(&pdev->dev)) {
    seq_printf(m, "is pf.\n");
    } else {
    seq_printf(m, "is vf.\n");
    }

    if(pdev->dev.bus->iommu_ops) {
        seq_printf(m, "%s line %d iommu ops is 0x%lx.\n", __func__, __LINE__, (unsigned long)pdev->dev.bus->iommu_ops);
    } else {
        seq_printf(m, "no iommuops.\n");
    }
    if(pdev->dev.dma_ops) {
        seq_printf(m, "%s line %d dma ops is 0x%lx.\n", __func__, __LINE__, (unsigned long)pdev->dev.dma_ops);
    } else {
        seq_printf(m, "no dma ops.\n");
    }

    return 0;
}
 
static int lookup_pci_drivers(struct device_driver *drv, void *data)
{
    struct seq_file *m = (struct seq_file *)data;
    seq_printf(m, "driver name %s.\n", drv->name);
 
    return 0;
}

static int lookup_platform_devices(struct device *dev, void *data)
{
    struct seq_file *m = (struct seq_file *)data;
    struct platform_device *platdev = to_platform_device(dev);
 
    seq_printf(m, "devpath %s.\n", platdev->name);
 
    return 0;
}
 
static int lookup_platform_drivers(struct device_driver *drv, void *data)
{
    struct seq_file *m = (struct seq_file *)data;
    seq_printf(m, "driver name %s.\n", drv->name);
 
    return 0;
}
 
static int list_device_belongs_todriver_pci(struct device *dev, void *p) 
{
    struct seq_file *m = (struct seq_file *)p;
    struct pci_dev *pdev = to_pci_dev(dev);
 
    seq_printf(m, "vendor id 0x%x, device id 0x%x, devname %s.\n", pdev->vendor, pdev->device, dev_name(&pdev->dev));
 
    return 0;
}

static int list_device_belongs_todriver_platform(struct device *dev, void *p) 
{
    struct seq_file *m = (struct seq_file *)p;
    struct platform_device *platdev = to_platform_device(dev);
 
    seq_printf(m, "platdevname %s.\n", platdev->name);
 
    return 0;
}

static int pcie_device_info_find_bridge(struct pci_dev *pdev, void *data)
{
    struct seq_file *m = (struct seq_file *)data;
    struct pci_bus *rootbus = NULL;
    rootbus = pci_find_bus(0, 0);

    if(pci_is_bridge(pdev)){
        seq_printf(m, "bridge find.vendor id 0x%x, device id 0x%x, devname %s. domain:0x%04x, BDF: %x:%x:%x, subordinate 0x%p, busid %d, rootbus %d rootself 0x%p.\n", \
            pdev->vendor, pdev->device, dev_name(&pdev->dev), pci_domain_nr(pdev->bus), pdev->bus->number, PCI_SLOT(pdev->devfn), PCI_FUNC(pdev->devfn), pdev->subordinate, 
        pdev->subordinate->number, rootbus->number, rootbus->self);
    }

    return 0;
}
 
static int pcie_device_info(struct pci_dev *pdev, void *data)
{
    struct seq_file *m = (struct seq_file *)data;
 
    seq_printf(m, "vendor id 0x%04x, device id 0x%04x, devname %s, belongs to bus %16s, parent bus name %6s subordinate 0x%p.\n", \
            pdev->vendor, pdev->device, dev_name(&pdev->dev), pdev->bus->name, pdev->bus->parent? pdev->bus->parent->name : "null", pdev->subordinate);
 
    if(pdev->subordinate) {
        seq_printf(m, "    subordinate have bus name %s.\n", pdev->subordinate->name);
        if(pdev->subordinate->self) {
            seq_printf(m, "        subordinate have dev name %s.\n", dev_name(&pdev->subordinate->self->dev));
            if(pdev->subordinate->self != pdev) {
                seq_printf(m, "            cant happend!\n");
            } else {
                seq_printf(m, "            surely!\n");
            }
        }
 
    } else {
        seq_printf(m, "    subordinate not have.\n");
    }
    
    if(pdev->bus->self) {
        seq_printf(m, "    device belongs to child pci bus %s.\n", dev_name(&pdev->bus->self->dev));
    } else {
        seq_printf(m, "    device belongs to top lvl pci bus.\n");
    }
 
    seq_printf(m, "\n");
    return 0;
}

struct zilong_attribute {
    struct attribute    attr;
    ssize_t (*show)(struct kobject *kobj, struct zilong_attribute *attr, char *buf);
    ssize_t (*store)(struct kobject *dev, struct zilong_attribute *attr,const char *buf, size_t count);
};

#define to_zilong_attr(_attr) container_of(_attr, struct zilong_attribute, attr)
static ssize_t zilong_attr_show(struct kobject *kobj, struct attribute *attr, char *buf)
{
    struct zilong_attribute *zlattr = to_zilong_attr(attr);
    zlattr->show(kobj, zlattr, buf);
    
    return 0;
}

static ssize_t zilong_attr_store(struct kobject *kobj, struct attribute *attr, const char *buf, size_t count)
{
    ssize_t size;

    struct zilong_attribute *zlattr = to_zilong_attr(attr);
    size = zlattr->store(kobj, zlattr, buf, count);

    return size;
}
static const struct sysfs_ops zilong_sysfs_ops = {
    .show   = zilong_attr_show,
    .store  = zilong_attr_store,
};

static struct kobj_type zilong_ktype = {
    .release        = NULL,
    .sysfs_ops      = &zilong_sysfs_ops,
    .namespace      = NULL,
    .get_ownership  = NULL,
};

ssize_t height_show(struct kobject *kobj, struct zilong_attribute *attr, char *buf)
{
    char *p = buf;

    p += sprintf(p, "I am 180 cm tall.\n");

    printk("%s line %d output %ld.\n", __func__, __LINE__, p - buf);
    return p - buf;
}

ssize_t height_store(struct kobject *dev, struct zilong_attribute *attr,const char *buf, size_t count)
{
    unsigned long height = 0;

    sscanf(buf, "%lx", &height);

    if (printk_ratelimit())
    printk("%s line %d, height %ld.\n", __func__, __LINE__, height);

    return count;
}

struct zilong_attribute height = {
    .attr = {
        .name = "height",
        .mode = 0777,
    },
    .show = height_show,
    .store = height_store,
};

static void f(struct super_block *sb, void *data)
{
    struct seq_file *m = (struct seq_file*)data;

    // for the sb->s_root dentry, d_parent is itself.
    seq_dentry(m, sb->s_root, " \t\n\\");
    seq_printf(m, "device %s.\n", sb->s_bdi->dev_name);
}

struct vfsmount *get_path_mount(char *path)
{
    struct path fspath;
    struct vfsmount *mnt;

    int err = kern_path(path, LOOKUP_FOLLOW, &fspath);
    if (err){
        printk(KERN_ERR "failed to get path.\n");
        return NULL;
    }

    mnt = fspath.mnt;

    return mnt;
}

#if 1
struct dentry *get_mount_entry(struct vfsmount *mnt, void **n, struct vfsmount **parent)
{
    void *p = NULL;
    p = mnt;
    mnt = p;
    return NULL;
}
#endif

struct dentry *get_mount_entry(struct vfsmount *mnt, void**, struct vfsmount **parent);
static void hack_mount(struct seq_file *m, struct vfsmount *mnt)
{
    struct path path;
    char buf[64];
    char *name;
    void *ptr;
    struct vfsmount *mt;

    struct dentry *dent = (struct dentry*) (*(unsigned long*)((unsigned long)mnt - sizeof(void*)));
    seq_printf(m, "mnt parent dentry name %s, %s.\n", dent->d_parent->d_name.name, dent->d_name.name);
    dent = get_mount_entry(mnt, &ptr, &mt);
    seq_printf(m, "mnt parent dentry name %s, %s, offset %ld.\n", dent->d_parent->d_name.name, dent->d_name.name, (unsigned long)ptr - (unsigned long)mnt);

    path.mnt = mnt;
    path.dentry=mnt->mnt_root;

    name = d_path(&path, buf, sizeof(buf));
    seq_printf(m, "mount dir is %s.\n", name);
    if(mt){
        struct vfsmount *cd = NULL;
        seq_printf(m, "parent fs is %s,mt=0x%px.\n", mt->mnt_sb->s_type->name,mt);
        get_mount_entry(mt, &ptr, &cd);
        if(cd) {
            seq_printf(m, "parent parent fs is %s cd=0x%px.\n", cd->mnt_sb->s_type->name, cd);
        } else {
            seq_printf(m, "parent parent fs is null.\n");
        }
    }
}

static void check_fs_mount(struct seq_file *m, char *path)
{
    struct vfsmount *mnt, *root;
        struct dentry* dentry = NULL;

    root = current->fs->root.mnt;

    mnt = get_path_mount(path);
    if(mnt){
        seq_printf(m, "fstype %s, info %s, mntroot %s, mntroot 0x%px, superroot %px, root %px.\n", \
                mnt->mnt_sb->s_type->name, mnt->mnt_sb->s_id, mnt->mnt_root->d_name.name, mnt->mnt_root, mnt->mnt_sb->s_root, root);
        seq_printf(m, "fstype %s, info %s, mntroot %s, mntroot 0x%px, superroot %px, root %px,mnt %px.\n", \
                root->mnt_sb->s_type->name, root->mnt_sb->s_id, root->mnt_root->d_name.name, root->mnt_root, root->mnt_sb->s_root, root, mnt);
        if(mnt->mnt_sb->s_root == mnt->mnt_root){
            seq_printf(m, "root identical.\n");
        } else {
            seq_printf(m, "root non-identical.\n");
        }

        dentry = mnt->mnt_root;
            while (dentry->d_parent != dentry) {
                dentry = dentry->d_parent;
            seq_printf(m, "dentry name %s.\n", dentry->d_name.name);
            }
        hack_mount(m, mnt);
    }
}

void list_all_mount_points(struct seq_file *m)
{
    //struct task_struct *task = get_current();

    check_fs_mount(m, "/");
    //check_fs_mount(m, "/home/zlcao/Workspace/linux/ramfs/mountdir");
    check_fs_mount(m, "/dev");
    check_fs_mount(m, "/tmp");
    check_fs_mount(m, "/var");
    check_fs_mount(m, "/dev/pts");
    check_fs_mount(m, "/home/zlcao/Workspace/zlramfs");

    return;
}

static int __process_all_devices(struct device *dev, void *data)
{
    struct seq_file *m = (struct seq_file*)data;
    if(dev->type == &i2c_adapter_type){
        struct i2c_adapter *adap = to_i2c_adapter(dev);
        seq_printf(m, "this is adaptor adaptor name %s dev name %s.\n", adap->name, dev_name(&adap->dev));
    }
    else if(dev->type == &i2c_client_type){
        struct i2c_client *clie = to_i2c_client(dev);
        seq_printf(m, "this is device %s, dev %s.\n", clie->name, dev_name(&clie->dev));
    }
    else
        seq_printf(m, "cant hanppend.\n");

    return 0;
}

static void probe_i2c_adaptor(struct seq_file *m, int id)
{
    struct i2c_adapter *adap;
    adap = i2c_get_adapter(id);
    if(!adap){
        seq_printf(m, "cant find i2c adaptor 6.\n");
        return;
    }
    //i2c_transfer(adap, msg, ...);
    seq_printf(m, "i2c adaptor name %s, i2c dev name %s.\n", adap->name, dev_name(&adap->dev));
    i2c_put_adapter(adap);

    i2c_for_each_dev(m, __process_all_devices);
}

void list_all_i2c_devices(struct seq_file *m)
{
    probe_i2c_adaptor(m, 0);
    probe_i2c_adaptor(m, 1);
    probe_i2c_adaptor(m, 2);
    probe_i2c_adaptor(m, 3);
    probe_i2c_adaptor(m, 4);
    probe_i2c_adaptor(m, 5);
    probe_i2c_adaptor(m, 6);
    probe_i2c_adaptor(m, 7);
    return;
}

typedef struct dmi_info_entry
{
    int id;
    char *name;
}dmi_info_entry_t;

#define DMI_ENTRY(idx) {.id = idx, .name = #idx}

dmi_info_entry_t dmi_tbl[] = {
    DMI_ENTRY(DMI_NONE),
    DMI_ENTRY(DMI_BIOS_VENDOR),
    DMI_ENTRY(DMI_BIOS_VERSION),
    DMI_ENTRY(DMI_BIOS_DATE),
    DMI_ENTRY(DMI_BIOS_RELEASE),
    DMI_ENTRY(DMI_EC_FIRMWARE_RELEASE),
    DMI_ENTRY(DMI_SYS_VENDOR),
    DMI_ENTRY(DMI_PRODUCT_NAME),
    DMI_ENTRY(DMI_PRODUCT_VERSION),
    DMI_ENTRY(DMI_PRODUCT_SERIAL),
    DMI_ENTRY(DMI_PRODUCT_UUID),
    DMI_ENTRY(DMI_PRODUCT_SKU),
    DMI_ENTRY(DMI_PRODUCT_FAMILY),
    DMI_ENTRY(DMI_BOARD_VENDOR),
    DMI_ENTRY(DMI_BOARD_NAME),
    DMI_ENTRY(DMI_BOARD_VERSION),
    DMI_ENTRY(DMI_BOARD_SERIAL),
    DMI_ENTRY(DMI_BOARD_ASSET_TAG),
    DMI_ENTRY(DMI_CHASSIS_VENDOR),
    DMI_ENTRY(DMI_CHASSIS_TYPE),
    DMI_ENTRY(DMI_CHASSIS_VERSION),
    DMI_ENTRY(DMI_CHASSIS_SERIAL),
    DMI_ENTRY(DMI_CHASSIS_ASSET_TAG),
    //DMI_ENTRY(DMI_STRING_MAX),
    DMI_ENTRY(DMI_OEM_STRING),
};

void dmi_info_verbose(struct seq_file *m)
{
    int i;
    
    for (i = 0; i < sizeof(dmi_tbl)/sizeof(dmi_info_entry_t); i ++){
        const char *s = dmi_get_system_info(dmi_tbl[i].id);
        if(s)
            seq_printf(m, "DMI %s INFO: %s.\n", dmi_tbl[i].name, s);
        else
            seq_printf(m, "DMI %s INFO is null.\n", dmi_tbl[i].name);
    }

    return;
}
void list_all_mount_device(struct seq_file *m)
{
#if 0
    struct nsproxy *nsp;
    struct task_struct *task = current;
    struct mnt_namespace *ns = NULL;
    struct list_head *p;
    struct mount *mnt, *ret = NULL;

    task_lock(task);
    nsp = task->nsproxy;
    if (!nsp || !nsp->mnt_ns) {
        printk("%s line %d. return error.\n", __func__, __LINE__);
        task_unlock(task);
        put_task_struct(task);
        return;
    }
    ns = nsp->mnt_ns;
    if (!task->fs) {
        printk("%s line %d. return error.\n", __func__, __LINE__);
        task_unlock(task);
        put_task_struct(task);
        return;
    }
    task_unlock(task);
    put_task_struct(task);

    list_for_each_continue(p, &ns->list) {
        mnt = list_entry(p, typeof(*mnt), mnt_list);
    }
    return;
#else
    struct file_system_type *fs_type;
    fs_type = get_fs_type("ext4");
    if(fs_type == NULL){
        printk("%s line %d. return error.\n", __func__, __LINE__);
        return;
    }

    iterate_supers_type(fs_type, f, m);
#endif
}
// 此函数将数据写入`seq_file`内部的缓冲区
// `seq_file`会在合适的时候把缓冲区的数据拷贝到应用层
// 参数@V是start/next函数的返回值
static int my_seq_ops_show(struct seq_file *m, void *v)
{
    struct task_struct *task = NULL;
    struct task_struct *tsk = NULL;
    struct task_struct *p = NULL;
    struct file *file = m->private;
    struct pid *session = NULL;
 
    if(seqfile_debug_mode == 0) {
        seq_puts(m, " file=");
        seq_file_path(m, file, "\n");
        seq_putc(m, ' ');
 
        task = (struct task_struct *)v;
        session = task_session(task);
        tsk = pid_task(session, PIDTYPE_PID);
        if(task->flags & PF_KTHREAD) {
            seq_printf(m, "Kernel thread output: PID=%u, task: %s, index=%lld, read_pos=%lld, %s.\n", task_tgid_nr(task),/* task->tgid,*/
                task->comm, m->index, m->read_pos, tsk? "has session" : "no session");
        } else {
            seq_printf(m, "User thread: PID=%u, task: %s, index=%lld, read_pos=%lld %s.\n", task_tgid_nr(task), /* task->tgid,*/
                task->comm, m->index, m->read_pos, tsk? "has session" : "no session");
        }

    seq_printf(m, "==================\n");
    sched_show_task(task);
    } else if(seqfile_debug_mode == 1) {
        struct task_struct *g, *p;
        static int oldcount = 0;
        static int entercount = 0;
        char *str;
 
        printk("%s line %d here enter %d times.\n", __func__, __LINE__, ++ entercount);
        seq_printf(m, "%s line %d here enter %d times.\n", __func__, __LINE__, ++ entercount);
 
        rcu_read_lock();
        for_each_process_thread(g, p) {
            struct task_struct *session = pid_task(task_session(g), PIDTYPE_PID);
            struct task_struct *thread = pid_task(task_session(p), PIDTYPE_PID);
            struct task_struct *ggroup = pid_task(task_pgrp(g), PIDTYPE_PID);
            struct task_struct *pgroup = pid_task(task_pgrp(p), PIDTYPE_PID);
            struct pid * pid = task_session(g);
 
            if(list_empty(&p->tasks)) {
                str = "empty";
            } else {
                str = "not empty";
            }
            seq_printf(m, "process %s(pid %d tgid %d,cpu%d) thread %s(pid %d tgid %d,cpu%d),threadnum %d, %d. tasks->prev = %p, \
                    tasks->next = %p, p->tasks=%p, %s, process parent %s(pid %d tgid %d), thread parent%s(pid %d, tgid %d, files %p\n)",
                    g->comm, task_pid_nr(g), task_tgid_nr(g), task_cpu(g), \
                    p->comm, task_pid_nr(p), task_tgid_nr(p), task_cpu(p), \
                    get_nr_threads(g), get_nr_threads(p), p->tasks.prev, p->tasks.next, &p->tasks, str, g->real_parent->comm, \
                    task_pid_nr(g->real_parent),task_tgid_nr(g->real_parent), p->real_parent->comm, task_pid_nr(p->real_parent), task_tgid_nr(p->real_parent), p->files);
 
            if(ggroup) {
                seq_printf(m, "ggroup(pid %d tgid %d).", task_pid_nr(ggroup),task_tgid_nr(ggroup));
            }
 
            if(pgroup) {
                seq_printf(m, "pgroup(pid %d tgid %d).", task_pid_nr(pgroup),task_tgid_nr(pgroup));
            }
 
            seq_printf(m, "current smp processor id %d.", smp_processor_id());
            if(thread) {
                seq_printf(m, "thread session %s(%d).", thread->comm, task_pid_nr(thread));
            }
            if(session) {
                seq_printf(m, "process session %s(%d).", session->comm, task_pid_nr(session));
            }
 
            if(oldcount == 0 || oldcount != m->size) {
                printk("%s line %d, m->count %ld, m->size %ld.", __func__, __LINE__, m->count, m->size);
                oldcount = m->size;
            }
 
            if(pid){
                seq_printf(m, "pid task %p,pgid task %p, psid_task %p", pid_task(pid, PIDTYPE_PID), pid_task(pid, PIDTYPE_PGID), pid_task(pid, PIDTYPE_SID));
                seq_printf(m, "pid task %s,pgid task %s, psid_task %s", pid_task(pid, PIDTYPE_PID)->comm, pid_task(pid, PIDTYPE_PGID)->comm, pid_task(pid, PIDTYPE_SID)->comm);
            }
            seq_printf(m, "\n");
        }
 
        rcu_read_unlock();
    } else if(seqfile_debug_mode == 2) {
        for_each_process(task) {
            struct pid *pgrp = task_pgrp(task);
 
            seq_printf(m, "Group Header %s(%d,cpu%d):\n", task->comm, task_pid_nr(task), task_cpu(task));
            do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
                seq_printf(m, "      process %s(%d,cpu%d) thread %s(%d,cpu%d),threadnum %d, %d.\n",
                    task->comm, task_pid_nr(task), task_cpu(task), \
                    p->comm, task_pid_nr(p), task_cpu(p), \
                    get_nr_threads(task), get_nr_threads(p));
            } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
        }
    } else if (seqfile_debug_mode == 3) {
        for_each_process(task) {
            struct pid *session = task_session(task);
            struct task_struct *tsk = pid_task(session, PIDTYPE_PID);
            if(tsk) {
                seq_printf(m, "session task %s(%d,cpu%d):", tsk->comm, task_pid_nr(tsk), task_cpu(tsk));
            } else {
                seq_printf(m, "process %s(%d,cpu%d) has no session task.", task->comm, task_pid_nr(task), task_cpu(task));
            }
 
            seq_printf(m, "session header %s(%d,cpu%d):\n", task->comm, task_pid_nr(task), task_cpu(task));
            do_each_pid_task(session, PIDTYPE_SID, p) {
                seq_printf(m, "      process %s(%d,cpu%d) thread %s(%d,cpu%d),threadnum %d, %d, spidtask %s(%d,%d).\n",
                    task->comm, task_pid_nr(task), task_cpu(task), \
                    p->comm, task_pid_nr(p), task_cpu(p), \
                    get_nr_threads(task), get_nr_threads(p), pid_task(session, PIDTYPE_SID)->comm, pid_task(session, PIDTYPE_SID)->tgid, pid_task(session, PIDTYPE_SID)->pid);
                if(pid_task(session, PIDTYPE_PID)) {
                    seq_printf(m, "pidtask %s(%d,%d).\n", pid_task(session, PIDTYPE_PID)->comm, pid_task(session, PIDTYPE_PID)->tgid, pid_task(session, PIDTYPE_PID)->pid);
                }
            } while_each_pid_task(pgrp, PIDTYPE_SID, p);
        }
    } else if(seqfile_debug_mode == 4) {
        struct task_struct *thread, *child;
        for_each_process(task) {
            seq_printf(m, "process %s(%d,cpu%d):\n", task->comm, task_pid_nr(task), task_cpu(task));
            for_each_thread(task, thread) {
                list_for_each_entry(child, &thread->children, sibling) {
                    seq_printf(m, "      thread %s(%d,cpu%d) child %s(%d,cpu%d),threadnum %d, %d.\n",
                        thread->comm, task_pid_nr(thread), task_cpu(thread), \
                        child->comm, task_pid_nr(child), task_cpu(child), \
                        get_nr_threads(thread), get_nr_threads(child));
                }
            }
        }
    } else if(seqfile_debug_mode == 5) { 
        struct task_struct *g, *t;
        do_each_thread (g, t) {
            seq_printf(m, "Process %s(%d cpu%d), thread %s(%d cpu%d), threadnum %d.\n", g->comm, task_pid_nr(g), task_cpu(g), t->comm, task_pid_nr(t), task_cpu(t), get_nr_threads(g));
        } while_each_thread (g, t);
    } else if(seqfile_debug_mode == 6) {
        for_each_process(task) {
            struct pid *pid = task_pid(task);
 
            seq_printf(m, "Process %s(%d,cpu%d) pid %d, tgid %d:\n", task->comm, task_pid_nr(task), task_cpu(task), task_pid_vnr(task), task_tgid_vnr(task));
            do_each_pid_task(pid, PIDTYPE_TGID, p) {
                seq_printf(m, "      process %s(%d,cpu%d) thread %s(%d,cpu%d),threadnum %d, %d. pid %d, tgid %d\n",
                        task->comm, task_pid_nr(task), task_cpu(task), \
                        p->comm, task_pid_nr(p), task_cpu(p), \
                        get_nr_threads(task), get_nr_threads(p), task_pid_vnr(p), task_tgid_vnr(p));
            } while_each_pid_task(pid, PIDTYPE_TGID, p);
        }
    } else if(seqfile_debug_mode == 7) {
        for_each_process(task) {
            struct pid *pid = task_pid(task);
 
            seq_printf(m, "Process %s(%d,cpu%d) pid %d, tgid %d:\n", task->comm, task_pid_nr(task), task_cpu(task), task_pid_vnr(task), task_tgid_vnr(task));
            do_each_pid_task(pid, PIDTYPE_PID, p) {
                seq_printf(m, "      process %s(%d,cpu%d) thread %s(%d,cpu%d),threadnum %d, %d. pid %d, tgid %d\n",
                    task->comm, task_pid_nr(task), task_cpu(task), \
                    p->comm, task_pid_nr(p), task_cpu(p), \
                    get_nr_threads(task), get_nr_threads(p), task_pid_vnr(p), task_tgid_vnr(p));
            } while_each_pid_task(pid, PIDTYPE_PID, p);
        }
    } else if(seqfile_debug_mode == 8) {
        bus_for_each_dev(&pci_bus_type, NULL, (void*)m, lookup_pci_devices);
        bus_for_each_drv(&pci_bus_type, NULL, (void*)m, lookup_pci_drivers);
        // class_find_device.
        // class_find_device_by_name.
        // class_for_each_device.
    } else if(seqfile_debug_mode == 9) {
        struct device_driver *drv; 
    int ret;

        drv = driver_find("pcieport", &pci_bus_type);
        ret = driver_for_each_device(drv, NULL, (void*)m, list_device_belongs_todriver_pci);
    } else if(seqfile_debug_mode == 10) {
        for_each_process(task) {
#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 7, 0)
            seq_printf(m, "Process %s(%d),state 0x%08x, exit_state 0x%08x, refcount %d, usage %d rcucount %d.", \
                task->comm, task->tgid, task->__state, task->exit_state, refcount_read(&task->stack_refcount), refcount_read(&task->usage), refcount_read(&task->rcu_users));
#else
            seq_printf(m, "Process %s(%d),state 0x%lx, exit_state 0x%08x, refcount %d, usage %d rcucount %d.", \
                task->comm, task->tgid, task->state, task->exit_state, refcount_read(&task->stack_refcount), refcount_read(&task->usage), refcount_read(&task->rcu_users));
#endif
            if(task->parent) {
                seq_printf(m, "parent name %s pid %d.\n", task->parent->comm, task->parent->tgid);
             } else {
                seq_printf(m, "no parent.\n");
            }
        }
    } else if(seqfile_debug_mode == 11) {
        struct pci_bus *bus;
        list_for_each_entry(bus, &pci_root_buses, node) {
            seq_printf(m, "pcibus name %s.\n", bus->name);
            pci_walk_bus(bus, pcie_device_info, (void*)m);
        }
    } else if(seqfile_debug_mode == 12) {
        struct device_driver *drv; 
    int ret;
        // EXPORT_SYMBOL(usb_bus_type);
        // bus_for_each_dev(&usb_bus_type, NULL, (void*)m, lookup_usb_devices);
        // bus_for_each_drv(&usb_bus_type, NULL, (void*)m, lookup_usb_drivers);
        bus_for_each_dev(&platform_bus_type, NULL, (void*)m, lookup_platform_devices);
        bus_for_each_drv(&platform_bus_type, NULL, (void*)m, lookup_platform_drivers);

        drv = driver_find("demo_platform", &platform_bus_type);
        ret = driver_for_each_device(drv, NULL, (void*)m, list_device_belongs_todriver_platform);
    } else if(seqfile_debug_mode == 13) {
        int ret;

        class_zilong = kset_create_and_add("zilong_class", NULL, NULL);
        if (!class_zilong) {
            printk("%s line %d, fatal error, create class failure.\n", __func__, __LINE__);
            return -ENOMEM;
        }

        ret = kobject_init_and_add(&kobj, &zilong_ktype, &class_zilong->kobj, "%s-%d", "zilong", 1);
        if(ret < 0) {
            printk("%s line %d, fatal error, create kobject failure.\n", __func__, __LINE__);
            return -ENOMEM;
        }

        kobj_created = 1;
        ret = sysfs_create_file(&kobj, &height.attr);
        if(ret != 0){
            printk("%s line %d, fatal error, create sysfs attribute failure.\n", __func__, __LINE__);
            return -ENOMEM;
        }
        kobj_created = 1;
    } else if(seqfile_debug_mode == 14) {
        // cad pid is process 1 pid.
        int ret = kill_cad_pid(SIGINT, 1);
        printk("%s lne %d ret %d.\n", __func__, __LINE__, ret);
    } else if(seqfile_debug_mode == 15) {
        kill_processes(pid_number);
    } else if(seqfile_debug_mode == 16) {
        struct pci_dev *pdev    = NULL;
        struct pci_dev *pparent = NULL;
        struct pci_bus *bus     = NULL;
        struct pci_bus *rootbus = NULL;
        struct pci_bus *findbus = NULL;
    
        findbus = pci_find_bus(0, 0);

        list_for_each_entry(rootbus, &pci_root_buses, node) {
            seq_printf(m, "pcibus name %s bus %p, findbus %p.\n", rootbus->name, rootbus, findbus);
            break;
        }

        bus_for_each_dev(&pci_bus_type, NULL, (void*)m, lookup_pci_devices_reset);

        pdev = g_pci_dev;
        if(pdev == NULL) {
            printk("%s line %d, return null.\n", __func__, __LINE__);
            return -1;
        }

        pci_reset_sbr(pdev);

        pci_lock_rescan_remove();
        pci_stop_and_remove_bus_device(pdev);
        pci_unlock_rescan_remove();

        bus = pdev->bus;
        //if (!pci_is_root_bus(bus) && list_empty(&bus->devices))
        if (0)
        {
            printk("%s line %d, lightweight rescan.\n", __func__,  __LINE__);
            pci_lock_rescan_remove();
            pci_rescan_bus_bridge_resize_priv(bus->self);
            pci_unlock_rescan_remove();
        } else {
            printk("%s line %d, rescan.\n", __func__,  __LINE__);
            if(bus->self) {
                bus = bus->self->bus;
                pparent = bus->self;
            }

            seq_printf(m, "%s line %d, do the reset of wireless device, device PCI BUS No.:%d. busname %s, bus %p.\n.", \
                    __func__, __LINE__, bus->number, bus->name, bus);

            if(pparent && pparent->bus) {
                seq_printf(m, "%s line %d, do the reset of wireless device, device PCI:0x%04x:%d:%d.%d\n.", \
                    __func__, __LINE__, pci_domain_nr(pparent->bus), pparent->bus->number, PCI_SLOT(pparent->devfn), PCI_FUNC(pparent->devfn));
            }

            if(bus == rootbus) {
                seq_printf(m, "warnings: reset root bus.\n");
            }

            pci_lock_rescan_remove();
            pci_rescan_bus(bus);
            pci_unlock_rescan_remove();
        }
    } else if(seqfile_debug_mode == 17) {
        struct pci_bus *pbus = NULL;

        while ((pbus = pci_find_next_bus(pbus)) != NULL) {
            seq_printf(m, "find bus %s.\n", pbus->name);  
        }

        list_for_each_entry(pbus, &pci_root_buses, node) {
            seq_printf(m, "pcibus name %s.\n", pbus->name);
            pci_walk_bus(pbus, pcie_device_info_find_bridge, (void*)m);
        }

        bus_for_each_dev(&pci_bus_type, NULL, (void*)m, lookup_pci_devices);
    } else if(seqfile_debug_mode == 18) {
        struct net *net;
        struct net_device *ndev;

        for_each_net(net)
            for_each_netdev(net, ndev) {
                seq_printf(m, "%s line %d, ndev->name %s. net 0x%p.\n", __func__, __LINE__, ndev->name, net);
            }
    } else if(seqfile_debug_mode == 19) {
    unsigned long *p;
    const struct cpumask *mask = cpu_cpu_mask(0);
    p = (unsigned long*)mask;
    seq_printf(m, "mask 0x%lx.\n", p[0]);
    } else if(seqfile_debug_mode == 20) {
    struct task_struct *process, *thread;
        rcu_read_lock();
        for_each_process_thread(process, thread) { 
            if (unlikely(thread->flags & PF_VCPU)) {
#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 7, 0)
            seq_printf(m, "%s line %d, comm %s, pid %d, is %s thread state 0x%x, proces %s(%d).\n", 
                    __func__, __LINE__, thread->comm, thread->pid, thread->mm? "user" : "kernel",thread->__state, process->comm, process->pid);
#else
            seq_printf(m, "%s line %d, comm %s, pid %d, is %s thread state 0x%lx, proces %s(%d).\n", 
                    __func__, __LINE__, thread->comm, thread->pid, thread->mm? "user" : "kernel",thread->state, process->comm, process->pid);
#endif
        }
       }
       rcu_read_unlock(); 
    } else if(seqfile_debug_mode == 21) {
        list_all_mount_device(m);
    } else if(seqfile_debug_mode == 22) {
        list_all_mount_points(m);
    } else if(seqfile_debug_mode == 23) {
        list_all_i2c_devices(m);
    } else if(seqfile_debug_mode == 24) {
     dmi_info_verbose(m);
    } else {
        printk("%s line %d,cant be here, seqfile_debug_mode = %d.\n", __func__, __LINE__, seqfile_debug_mode);
    }
 
    return 0;
}

static struct task_struct *find_lock_task_mm(struct task_struct *p)
{
    struct task_struct *t;

    rcu_read_lock();
    for_each_thread(p, t) {
        task_lock(t);
        if (likely(t->mm))
            goto found;
        task_unlock(t);
    }

    t = NULL;
found:
    rcu_read_unlock();
    return t;
}  

static bool process_shares_task_mm(struct task_struct *p, struct mm_struct *mm)
{
    struct task_struct *t;
    for_each_thread(p, t) {
        struct mm_struct *t_mm = READ_ONCE(t->mm);
        if (t_mm)
            return t_mm == mm;
    }
    return false;
} 

static void kill_processes(int pid_nr)
{
    struct task_struct *victim;
    struct task_struct *p;
    struct mm_struct *mm;
    int old_cnt,new_cnt;

    victim = get_pid_task(find_vpid(pid_nr), PIDTYPE_PID);
    if(victim == NULL) {
        printk("%s line %d,return.\n", __func__, __LINE__);
        return;
    }

    printk("%s line %d, task has live %d threads total.\n", __func__, __LINE__, atomic_read(&victim->signal->live));

    p = find_lock_task_mm(victim);
    if (!p) {
        put_task_struct(victim);
        return;
    } else {
        get_task_struct(p);
        put_task_struct(victim);
        victim = p;
    }

    mm = victim->mm;
    mmgrab(mm);

    kill_pid(find_vpid(pid_nr), SIGKILL, 1);
    task_unlock(victim);

    rcu_read_lock();
    for_each_process(p) {
        if (!process_shares_task_mm(p, mm))
            continue;
        if (same_thread_group(p, victim))
            continue;
        if (unlikely(p->flags & PF_KTHREAD))
            continue;
        kill_pid(get_pid(task_pid(p)), SIGKILL, 1);
   }

   rcu_read_unlock(); 
   mmdrop(mm);

   old_cnt = atomic_read(&victim->signal->live);
   while((new_cnt=atomic_read(&victim->signal->live))) {
    if(new_cnt != old_cnt) {
            printk("%s line %d, live %d.\n", __func__, __LINE__, atomic_read(&victim->signal->live));
        old_cnt = new_cnt;
    }
   }

   put_task_struct(victim);
}
 
static const struct seq_operations my_seq_ops = {
    .start  = my_seq_ops_start,
    .next   = my_seq_ops_next,
    .stop   = my_seq_ops_stop,
    .show   = my_seq_ops_show,
};

static int proc_seq_open(struct inode *inode, struct file *file)
{
    int ret;
    struct seq_file *m;
 
    ret = seq_open(file, &my_seq_ops);
    if(!ret) {
        m = file->private_data; 
        m->private = file;
    }
 
    return ret;
}
 
static ssize_t proc_seq_write(struct file *file, const char __user *buffer, size_t count, loff_t *pos)
{
    char debug_string[16];
    int debug_no;
 
    memset(debug_string, 0x00, sizeof(debug_string));
    if (count >= sizeof(debug_string)) {
        printk("%s line %d, fata error, write count exceed max buffer size.\n", __func__, __LINE__);
        return -EINVAL;
    }
 
    if (copy_from_user(debug_string, buffer, count)) {
        printk("%s line %d, fata error, copy from user failure.\n", __func__, __LINE__);
        return -EFAULT;
    }
 
    if (sscanf(debug_string, "%d", &debug_no) <= 0) {
        printk("%s line %d, fata error, read debugno failure.\n", __func__, __LINE__);
        return -EFAULT;
    }
 
    seqfile_debug_mode = debug_no;
 
    //printk("%s line %d, debug_no %d.\n", __func__, __LINE__, debug_no);
 
    return count;
}
 
static ssize_t proc_seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
{
    ssize_t ret;
 
    printk("%s line %d enter, fuck size %lld size %ld.\n", __func__, __LINE__, *ppos, size);
    ret = seq_read(file, buf, size, ppos);
    printk("%s line %d exit, fuck size %lld size %ld,ret = %ld.\n", __func__, __LINE__, *ppos, size, ret);
 
    return ret;
}
 
#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 7, 0)
static const struct proc_ops seq_proc_ops_new = {
    .proc_open      = proc_seq_open,
    .proc_read      = proc_seq_read,
    .proc_lseek     = seq_lseek,
    .proc_release   = seq_release,
    .proc_write     = proc_seq_write,
};
#else
static struct file_operations seq_proc_ops = {
    .owner      = THIS_MODULE,
    .open       = proc_seq_open,
    .release    = seq_release,
    .read       = proc_seq_read,
    .write      = proc_seq_write,
    .llseek     = seq_lseek,
    .unlocked_ioctl = NULL,
};
#endif
 
static struct proc_dir_entry * entry;
static int proc_hook_init(void)
{
    printk("%s line %d, init. seqfile_debug_mode = %d.\n", __func__, __LINE__, seqfile_debug_mode);

#if 1
#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 7, 0)
    entry = proc_create("dumptask", 0644, NULL, &seq_proc_ops_new);
#else
    entry = proc_create("dumptask", 0644, NULL, &seq_proc_ops);
#endif
#else
    entry = proc_create_seq("dumptask", 0644, NULL, &my_seq_ops);
#endif
    return 0;
}
 
static void proc_hook_exit(void)
{
    if(kobj_created) {
        kobject_del(&kobj);
        kset_unregister(class_zilong);
    }

    proc_remove(entry);
 
    printk("%s line %d, exit.\n", __func__, __LINE__);
 
    return;
}
 
module_init(proc_hook_init);
module_exit(proc_hook_exit);
MODULE_AUTHOR("zlcao");
MODULE_LICENSE("GPL");

黑/白名单机制

基于dmi得到的信息，可以在内核驱动中实现黑/白名单机制，这样驱动可以在不同的服务器/主机上有不同的行为,对行为进行除权/授权。比如针对本机DMI信息建立一个白名单：